LESSON PLAN FORMAT
TITLE: How Sweet it Is (or Isn’t)
KEY QUESTION(S): The key question or questions the lesson will explore include:
How are small molecules detected and analyzed?
What physical and chemical properties of a compound define its use as a commercial product?
What controversy, ethical questions and concerns are important in
SCIENCE SUBJECT: Biotechnology
GRADE AND ABILITY LEVEL: Junior/Senior/Honors Level
SCIENCE CONCEPTS: Apply knowledge of the nature of science and scientific habits of mind to solve problems and
employ safe and effective use of laboratory technologies
OVERALL TIME ESTIMATE: 8-45 minute class periods
LEARNING STYLES: Visual, auditory, and kinesthetic.
VOCABULARY:
aspartame
sucrose
phenylalanine
aspartyl-phenylalanine-1-methyl ester
dipeptide
aspartic acid
hydrolyzed (hydrolysis) methanol
formic acid
phenylketonuria
excitotoxins
diketopiperazine
LESSON SUMMARY: This lab will expose students to the analytical technique of mass spectrometry. The application of
the technique will provide students with the ability to test for the presence of aspartame and its decomposition
products in solutions in which pH, temperature and buffer vary.
STUDENT LEARNING OBJECTIVES WITH STANDARDS:
Standards
24.0 Apply knowledge of the nature of science and scientific habits of
mind to solve problems, and employ safe and effective use of
laboratory technologies.
25.0 Demonstrate understanding of the chemical processes in
biotechnology, pH, solutions, dilutions, molarity
27.0 Demonstrate an understanding of the fundamentals of
biochemistry
38.0 Apply basic skills in scientific inquiry, calculations, and analysis.
40.0 Utilize materials processing and standard laboratory operating
procedures for biotechnology.
55.0/42.0 Demonstrates knowledge of basic chemistry as applied to
biotechnology procedures.
Specifically the student will be able to...
1. Identify artificial sweeteners (a biotechnology product)and consumer products which contain these
2. Prepare stock solutions and perform serial dilutions of an aspartame standard
55/42.09 Use stoichiometry and molarity to prepare solutions of any volume and
concentration.
55/42.10 Prepare dilutions of concentrated solutions
3. Design an experiment to prepare samples for a mass spectrometry and test for the
degradation of aspartame under a variety of conditions including heat, pH and type of
buffer
24.01
38.01
38.03
42.05
42.06
Know that investigations are conducted to explore new phenomena, to check on
previous results, to test how well a theory predicts, and to compare different theories
Develop scientific questions, hypotheses, and experimental plans.
Calculate ratios used for making chemical dilutions or plate counting.
Explain and use the function of pH in the preservation, purification, and
functioning of proteins.
Use pH paper or pH meter to measure and adjust pH.
4. Properly and safely operate the Advion Expression CMS
38.02
42.04
Properly and safely operate scientific equipment including mixers, analytical balances,
stirrers, shakers, conductivity meters, and a hemocytometer.
Discuss and use techniques that identify and separate components of a
homogenous mixture.
5. Interpret mass spectrograph for samples analyzed by the instrument
40.03
MATERIALS: ESSENTIAL:
Perform a variety of biological tests and chemical assays, collect data, perform
calculations and statistical analysis.
Per class:
Advion Expression CMS , teacher manual and accompanying locker
Aspartame, analytical standard Sigma: 47135(C14H18N2O5, MW = 294)
(This is only 0.5g of aspartame)
Aspartic acid, Sigma 219096-25G (C4H7NO4, MW = 133)
Aspartylphenylalanine, Sigma 421669 -100mg (C13H16N2O5, MW = 280)
Diketopiperazine, Sigma 421650-250mg (C13H14N2O4, MW =262)
Phenylalanine, Sigma P2126-100G (C9H11NO2, MW = 165)
Phenylalanine methyl ester, P17202-10G,(C6H5CH2CH(NH2)COOCH3 · HCl
Water bath or heat source (30oC to 99oC)
MW = 215)
Phosphate buffers at pH = 6.2 and 8.0 (mono and dibasic NaPO4-see below)
Citrate buffer at pH = 6.2 and 4.6
Per group of 3-4 students
Test tubes to perform serial dilution of standards
Pipets and Micro-pipets
Student supplied samples with aspartame
BACKGROUND INFORMATION: In 1965 Mr. James Schlatter, a chemist at G.D. Searle & Company, failed to follow
correct safety protocol. Schlatter was attempting to make a gastric inhibitory polypeptide as a possible anti-ulcer
medicine. After working in the lab, and not washing his hands, he licked his finger to pick up a paper when he tasted an
intense sweetness. On his hands was the intermediate compound he had synthesized, something that was 180 to 200
times sweeter than sucrose, or table sugar. Mr. Schlatter had discovered a new artificial sweetener. In 1970’s, G.D.
Searle & Company went on to name and patent this compound as aspartame. In 1974, FDA approved aspartame use in
carbonated beverages and in dry food products and it was finally cleared as a
general sweetener in 1996. Aspartame is the name for the artificial, noncarbohydrate sweetener, aspartyl-phenylalanine-1-methyl ester. The name
indicates it is the methyl ester of a dipeptide with the amino acids aspartic acid
and phenylalanine. It is marketed under a number of trademark names, the
most well known as Equal and NutraSweet, and is an ingredient of consumer
foods and beverages sold worldwide. It is commonly used in diet soft drinks,
chewing gum and is often provided as a table condiment. Aspartame is a
common sugar substitute used by diabetics. Upon ingestion, aspartame is
digested as a protein, rapidly hydrolyzed in the small intestines into residual
components-- aspartic acid, phenylalanine, and methanol. Methanol is further metabolized to formaldehyde and formic
acid (accumulation of the latter being suspected as the major cause of injury in methanol poisoning). Human studies
show that formic acid is excreted faster than it is formed after ingestion of aspartame and is not considered a concern.
It is noted that the amount of methanol produced from aspartame in beverages is less than concentrations of methanol
found in some fruit juices. These metabolites have been studied in a wide range of populations including infants,
children, adolescents, and healthy adults. In healthy adults and children, even enormous doses of aspartame do not lead
to plasma levels of metabolites that are a concern for safety.
Since aspartame produces the naturally-occurring essential amino acid phenylalanine, it is a health hazard to the few
people born with phenylketonuria, a congenital inability to process phenylalanine. Aspartic acid is an amino acid
commonly found in foods. Approximately 40% of aspartame (by mass) is broken down into aspartic acid. Because
aspartame is metabolized and absorbed very quickly (unlike aspartic acid-containing proteins in foods), it is known that
aspartame could spike blood plasma levels of aspartate. Aspartic acid is in a class of chemicals known as excitotoxins.
Abnormally high levels of excitotoxins have been shown in hundreds of animal studies to cause damage to areas of the
brain unprotected by the blood-brain barrier and a variety of chronic diseases arising out of this neurotoxicity. These
findings, however have not raised serious concerns and aspartame is used by more than 100 million people around the
world and is found in more than 6,000 products. This low-calorie sweetener has been extensively researched and more
than 200 studies have been conducted.
Even with its widespread use, aspartame is not appropriate in all food products. The stability of aspartame is dependent
on time, temperature, pH and water activity. Basically as a peptide, it is susceptible to hydrolysis (cleavage of chemical
bonds by the addition of water). Aspartame is very stable in the dry state: at 105°C a loss of approximately 5% (forming
an additional degradation product—the cyclic dipeptide called diketopiperazine) is observed after 100 hours of
treatment. At 120°C, a 50% loss is obtained after 80 hours of treatment. In solution, when stored at temperatures
ranging from 30 to 80°C, aspartame is progressively degraded into diketopiperazine. It is therefore not usable in foods
heated at higher temperature (cooking, sterilization, etc.). At room temperature its stability is good at pH values of
between 3.4 and 5 and it is maximally stable at pH 4.3. At pH below 3.4 the dipeptide is hydrolyzed and at a pH greater
than 5, cyclization occurs with the formation of diketopiperazine. In both cases, this transformation results in the loss of
sweetness. Also, the main impurity (approximately 2%) is diketopiperazine. The solubility of aspartame in water is
dependent on pH and temperature, the maximum solubility is reached at pH 2.2 (20 mg/ml at 25°C) and the minimum
solubility at pH 5.2 (pH) is 13.5 mg/ml at 25°C.
Aspartame provides the basis for a study of a common food additive encountered frequently by a student population.
Given its history as a successful, yet controversial product, this topic also allows for a study of the development of a
controversial product, product testing, food additive safety and consideration for sensitive populations. Aspartame is
not an unusual molecule (basically a dipeptide) and can easily be included in a unit on (the biomolecule) protein. As a
small peptide easily degraded, aspartame also provides a vehicle to study factors that are important to biomolecular
stability. Its degradation products and metabolites readily take on a charge and therefore are ideal for analysis using
electrospray ionization mass spectrometry providing a means for studying how peptides and other molecules are
analyzed. Ultimately students may dilute a beverage sample and inject the diluted sample into the ESI-MS. The lab is
procedurally simple and the results clearly demonstrate the potential and limitations of ESI-coupled mass spectrometry.
ADVANCE PREPARATION: What the teacher needs to do to get ready for the lesson
 Copy student handouts
 Prepare solutions: (Alternatively, students may be asked to prepare solutions)
1. 0.1M (100mM) aspartame solution (0.5g – dissolved in 16.9mL of solution =
X mL = 0.5g X 1Mole/295g X 1L/0.1 mole X 1000mL/1L = 16.9mL
(If this does not dissolve well add, dropwise, 0.1M HCl until completely dissolved)
Aliquot into 1mL samples and freeze
2. Buffers
a. Citrate Buffer (sodium citrate-citric acid buffer) pH 3-6.2
Stock solutions: X = 0.2M citric acid
C6H807*H20 (MW = 210.14) 42.02 gm (1 liter )
Y = Sodium citrate 0.2M = 58.8 gm/1L Na3C6H507*H20 (MW = 294.12)
Mix 0.2M citric acid (X) and 0.2M sodium citrate (Y) to give desired pH.
Dilute with 100mL ddH2O to desired molarity (0.1M). Final volume =200mL
pH
(25 C) X ml Y ml
4.6
25.5 24.5
6.2
7.2
42.8
b. Phosphate buffer (mono and dibasic sodium phosphate) pH
Stock solutions: X = 0.2M dibasic sodium phosphate ( 1 liter )
Na2HPO4*2H20 (MW = 178.05) 35.61 gm or
Na2HPO4*7H20 (MW = 268.07) 53.65 gm or
Na2HPO4*12H20 (MW = 358.14) 71.64 gm + ddH20 to make 1 liter
Y = 0.2M monobasic sodium phosphate ( 1 litter )
NaH2PO4*H20 (MW = 138.01) 27.6 gm or
NaH2PO4*2H20 (MW = 156.03) 31.21 gm + ddH20 to make 1 liter
Working buffer: 0.1M 100 ml
Mix X ml of 0.2M dibasic sodium phosphate with Y ml 0.2M monobasic sodium
phosphate.
Dilute with 50 ml ddH2O to desired molarity (0.1M) . Final volume = 100mL
pH
6.2
8.0
(25 C)
X ml Y ml
9.25 40.75
47.35 2.65
PROCEDURE AND DISCUSSION QUESTIONS WITH TIME ESTIMATES:
Day 1 – As a portion of a unit on proteins…introduce asparatame as a dipeptide and then expand the discussion
to include other non-sugar sweeteners. SEE WORKSHEET How sweet it is to be completed in small
groups. Use of computers
Day 2- Groups share information on artificial sweetener
Discuss student preference for sweeteners
Controversy regarding sweeteners
Would sucrose be an approved sweetener if introduced today?
Introduce the mass spectrometer as an analytical method
Handout aspartame degradation product work sheet
Day 3 Students complete degradation product worksheet
Handout instructions for lab and assign each group an experimental condition to test
Day 4 Students prepare samples for ESI-MS/experimental conditions met by each group
Day 5 Student samples run on MS
Day 6 Student share results of samples. Assign reading
Day 7 Students complete lab reports – prepare student samples
Day 8 Students supplied samples run on MS
ASSESSMENT SUGGESTIONS: Describe specific assessments for EACH objective:
Objective 1… Worksheets provided with structure of artificial sweeteners. Collected, scored and results discussed
Objective 2-5.See attached worksheet and lab report. Guided questions to be answered and discussed in group setting
EXTENSIONS:
ACTIVITIES: Coordinate with chemistry when introducing important concepts of bond types (ionic, polar
covalent and covalent and solubility) and determining masses from formulas . The topic mass
spectrometry is introduced as a “Chemistry in Action” in Chapter 7 (Chemical Formulas and
Chemical Compounds) of the Holt, Modern Chemistry text used in Ponte Vedra High School.
Consider the development of aspartame as a commercial product. Perform a Socratic Seminar to
discuss issues surrounding product development and product controversy.
What scientific procedures are utilized to develop and test a new product?
Has the US Government and the FDA been effective in protecting food from unsafe
additives?
How well do companies evaluate products for being both effective and safe?
Would sucrose, if introduced into the market today, be considered both effective and
safe?
Study could be repeated, but analyzed using thin-layer chromatography.
Current events (see attached readings) and reading activity
Provide a seminar on phenylketonuria.
LITERATURE: NutraSweet, A Case-Study Component of ChemCases;A Case-Study General Chemistry Curriculum
Supported by the National Science Foundation http://chemcases.com/nutra/nutra3.htm
RESOURCES/REFERENCES:
Bergen ,H. Robert III, Linda M. Benson and Stephen Naylor Determination of Aspartame and Caffeine in Carbonated
Beverages Utilizing Electrospray Ionization-Mass Spectrometry J. Chem. Educ., 2000, 77 (10), p 1325
Pattanaargson S, Sanchavanakit C, Aspartame degradation study using electrospray ionization mass spectrometry.
Rapid Commun Mass Spectrom. 2000;14(11):987-93.
Bell LN, Labuza, Aspartame stability in commercially sterilized flavored dairy beverages , TPJ Dairy Sci. 1994
Jan;77(1):34-8
http://chemcases.com/nutra/nutra3.htm
How Sweet It Is (or Isn’t)
Aspartame and its Metabolites
Name___________________________
Discovered serendipitously in 1965, and then studied carefully for the next 30 years, aspartame has become a common
food additive in soft drinks, chewing gum and other food products since the 1990’s. But, because of its chemical
composition, it cannot be used in all foods. Its basic structure is that of a peptide and, even though the peptide bond is
quite strong, the shelf life of any peptide in solution is very limited. Once placed in solution, hydrolysis of the bonds can
take place, especially at high or low pH. The presence of proteases (from microbes in a solution) also assists with the
decomposition of the peptide bond. None of the decomposition products are sweet. So, aspartame is not well suited
for baking, because it breaks down when heated and loses much of its sweetness. Once ingested, aspartame behaves as
a peptide, rapidly hydrolyzed in the small intestines into residual components-- aspartic acid, phenylalanine, and
methanol. Methanol undergoes additional metabolism to formaldehyde and then formic acid.
Objective:
To identify the components which contribute to the compound aspartame.
To determine the potential products of aspartame metabolism and degradation
1. First write the structure of each chemical component found in aspartame (a to c), then identify each in the
structures of aspartame in figure 1(d and e) by coloring the atoms contributed by aspartic acid with blue, the
phenylalanine atoms in green and the methanol atoms in red.
a.
b.
Aspartic Acid
c.
Phenylalanine
Methanol
Figure 1. The following structures are two representations of the artificial sweetener aspartame. It is
synthesized in a reaction that combines two amino acids and methanol. Identify each part in the structures in
figure 1(d and e) by coloring atoms from the aspartic acid with blue, the phenylalanine in green and the
methanol in red
d.
e.
2. Identify each component in the structure of aspartame in figure 2 (f to k) by coloring the atoms attributed to
aspartic acid with blue, the phenylalanine atoms in green and the methanol atoms in red. Report the molecular
formula and molar mass of each compound.
Figure 2. Shown below is a possible degradation pathway of aspartame. Different degradation species of aspartame
are possible in solution and are dependent upon pH and temperature.
f.
f. Aspartame
Formula______________
g.
Mass
______________
g. Methanol
Formula______________
h.
Mass
______________
h. L-aspartyl-L-phenylalanine
Formula______________
i.
Mass
______________
i. Diketopiperazine
Formula______________
Mass
j.
______________
j. Phenylalanine
Formula______________
k.
Mass
______________
k. Aspartic acid
Formula______________
Mass
______________
3. Compare the products above for elemental content, functional groups, or mass.
Compounds that contain carbon, oxygen, nitrogen and oxygen ________________________________________
Chemical functional groups present. Which compounds have:
a benzene ring _______________a carboxylic acid group_____________ an amine group?____________
How do the compounds vary the most? elemental content
functional groups
or
mass
4. Can any of these compounds be converted to an ionic form? Which? What groups would accept a proton?
______________________________________________________________________________________________
Biotechnology II
Proteins: Analysis of a Peptide
Mass Spectrometry for Molecular Identification
LEARNING GOALS
Skills: Can you…






Calculate the correct molar mass for a compound.
Prepare solutions of known concentration and dilution.
Design an experiment to test for the effect of temperature, pH and solvent on a compound
Use mass spectrometry to identify decomposition products of a compound.
Describe the meaning in different spectral patterns produced by a mass spectrometer
Write a scientific report with a concluding statement outlining the results of an experiment. Provide
evidence, explanations, error analysis, and practical applications.
Concepts: A focus on learning standard: Investigations are conducted to explore new phenomena, to check on
previous results, to test how well a theory predicts, and to compare different theories. Do you understand that..
 New scientific discoveries often result due to chance or unexpected results.
 New products require testing to determine purity, authenticity and decomposition products.
 Compound integrity is dependent upon conditions of temperature, pH and shelf life
 Several parameters can be (or must be) used to determine the identity of a compound
 Mass spectrometry is the most accurate technique available to measure the mass of an individual molecule
 Knowing molecular mass is essential when identifying an unknown compound
OUTLINE
A. Introduction and background information provided. Complete previous assignments
B. Prepare standard solutions at appropriate concentrations
1. Aspartame and expected degradation products are prepared at a concentration necessary for
electrospray mass spectrometry
2. Identify consumer products with aspartame and prepare for testing with ES-MS
C. Define conditions that will contribute to the degradation of aspartame, exposing samples to differing
conditions of pH or temperature
D. Analyze samples using electrospray mass spectrometry
E. Record results, share in a collaboration with class mates and define optimal conditions for storage and use of
aspartame
MASTERY RUBRIC
Level 4
Level 3
Level 2
Level 1
Including level three
understanding, the student led
the group in completing tasks and
handed papers in on time or
early. In- depth analysis or results
provided applications that go
beyond what was taught in class.
The student’s work indicates an
The student’s work indicates errors
or omissions regarding the learning
goals but did not indicate major errors
or omit information that was relative
to the easiest information and
processes. Helped lab partners
complete tasks when asked
The student provided little help in
completing lab and lab results are
copied from another student’s lab
report. Analysis indicates a distinct
lack of understanding of the
knowledge. Papers were handed in
several days after all other students.
understanding of learning goals
and the student helped lab
partners with tasks used to
complete this assignment. Papers
handed in on time
Introduction and background information.
After James M. Schlatter first tasted a sweet residue on his finger in 1965, it propelled G.D. Searle & Company into a new
industry, creating the nutritive artificial sweetener aspartame. Scientists at G. D. Searle continued to synthesize
compounds of similar structure. They wanted to determine if a closely related material might be a better sweetener. As
a business, Searle wanted to work on the most cost-efficient and effective pathway to make the compound, and to
protect its property interests by gaining patents for the compound.
Once aspartame was established as the candidate sweetener, G.D. Searle and Company also needed to assess what
were the best products in which to use the new sweetener. How stable is it in these new formulations and, how,
exactly, does the human body metabolize this new compound? To answer all these questions required an essential
research skill – molecular identification.
The ability to identify a molecule is critical to not only product discovery, but many disciplines including environmental
science, forensics, medicine and astronomy and more. It is especially important in drug/product discovery. Yet
molecules can only be characterized in an indirect fashion. The researchers perform experiments that generate hints
about the structure using chromatographic or spectroscopic methods or X-ray diffraction. With this information,
researchers can then propose a structure that agrees with all of the data and demonstrate that no alternative structure
is possible. One of the most important values in confirming a structure is a mass that matches the structure. One of the
primary means of characterizing molecules is mass
spectrometry.
Mass spectrometry (MS) is an analytical technique that produces
spectra (singular spectrum) of the masses of the molecules in a
sample of material. The spectra can be used to determine the
elemental composition of a sample, the masses of particles and
of molecules, and to elucidate the chemical structures of
molecules, such as peptides and other chemical compounds
when compared to standards. Mass spectrometry works by
ionizing chemical compounds to generate charged molecules or
molecule fragments and then measuring their mass-to-charge
ratios.
A mass spectrometer consists of three components: an ion source, a mass analyzer, and a detector. The ionizer converts
a portion of the sample into ions. There are a wide variety of ionization techniques, depending on the phase (solid,
liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction
system removes ions from the sample, which are then moved about and manipulated by external electric and magnetic
fields through the mass analyzer and onto the detector. The difference in masses of the fragments allows the mass
analyzer to sort the ions by their mass-to-charge ratio. The separated ions are then measured, and the results displayed
on a chart.
Techniques for ionization have been critical to determining what types of samples can be analyzed by mass
spectrometry. Two techniques often used with liquid and solid biological samples include electrospray ionization and
matrix-assisted laser desorption/ionization (MALDI). John Bennett Fenn was awarded the 2002 Nobel Prize in Chemistry
for the development of electrospray ionization mass spectrometry in the late 1980s. In this procedure the liquid to be
analyzed is dispersed by electrospray into a fine aerosol. Because the ion formation involves extensive solvent
evaporation (also termed desolvation), the typical solvents for electrospray ionization are prepared by mixing water with
volatile organic compounds (e.g. methanol, acetonitrile). To decrease the initial droplet size, compounds that increase
the conductivity (e.g. acetic acid) are customarily added to the solution. These species also act to provide a source of
protons to facilitate the ionization process.
In this lab we will use the Advion expression Compact Mass Spectrometer to analyze aspartame and its degradation
products.
Essential question to be answered: Can aspartame be detected using mass spectrometry? Under what conditions is the
artificial sweetener destroyed? Can the products produced from aspartame be detected by mass spectrometry?
Procedure:
A. Safety concerns: Follow the rules for working the a Laboratory
1. Wear protective eyewear and lab coats
2. Be cautious with solvents and chemicals
3. Follow directions for the use of equipment.
4. Wash your hands.
5. Never pipette by mouth
6. Do not eat or drink in the lab
7. Label everything clearly.
8. Autoclave or disinfect all waste material.
9. Clean up spills with care.
For this lab student groups will be assigned to test the stability of aspartame in various conditions. These conditions will
be as follows:
1. Aspartame in water, held at 4oC overnight (control)
2. Aspartame in water, held at room temperature overnight, return to 4oC
3. Aspartame in water, held at 170oC for 2 hours (this is approximately 350oF, a common temperature for baking)
4. Aspartame in a citrate buffer, pH 4.6 (citrate is often used to add an acidic or sour taste to foods and soft
drinks)
5. Aspartame in a citrate buffer, pH 6.2
6. Aspartame in a phosphate buffer, pH 6.2 (phosphate is the most important intracellular buffer)
7. Aspartame in a phosphate buffer, pH 8.0
See questions to answer on student report.
B. Treatment of aspartame.
a. Each group will be given 1mL of a 100mM (1 x 10-1 M) sample of aspartame.
b. Each group will dilute the sample 1:10 using the appropriate solvent. This is completed by adding the 1mL
sample to 9mL of solvent
Groups 1, 2 and 3 will use water (place the 10mL at the experimental temperature, aliquot if necessary,
determine pH)
Groups 4 and 5 will use citrate buffer at the appropriate pH
Groups 6 and 7 will use phosphate buffer at the appropriate pH
Aspartame is now at a concentration of 10mM (1 x 10-2M). This concentration is comparable to a diet soda.
C. Preparing solutions for analysis in ESI-MS (spray solutions)
Label all tubes with name of contents, concentration, date, your initials. Store at 4oC.
Experimental samples
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Each will need to be diluted to this value
Describe a serial dilution scheme to dilute 1mL of experimental sample (it is 10mM) to a 1mM
concentration in 70% methanol.
Standards for aspartame degradation products
Aspartylphenylalanine (0.1g – MW =280)
Dilute 0.1g sample to 35.7mL of solution (it is now 10mM or 1 X10-3M)
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Describe a serial dilution scheme
to dilute 1mL of experimental sample (it is 10mM) to a 1mM concentration in 70% methanol.
Diketopiperazine (0.25g - MW =262)
Dilute 0.25g sample to 95.4mL of solution (it is now 10mM or 1 X10-3M)
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Describe a serial dilution scheme
to dilute 1mL of experimental sample (it is 10mM) to a 1mM concentration in 70% methanol.
Aspartic acid (25g - MW = 133)
Weigh 0.133 grams of aspartic acid and dissolve in 100mL of solution (it is now 10mM or 1 X10-3M)
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Describe a serial dilution scheme
to dilute 1mL of experimental sample (it is 10mM) to a 1mM concentration in 70% methanol
Phenylalanine (100g - MW = 165)
Weigh 0.165 grams of phenylalanine and dissolve in 100mL of solution (it is now 10mM or 1 X10-3M)
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Describe a serial dilution scheme
to dilute 1mL of experimental sample (it is 10mM) to a 1mM concentration in 70% methanol
Phenylalanine methyl ester PME (10g - MW = 215)
Weigh 0.215 grams of PME and dissolve in 100mL of solution (it is now 10mM or 1 X10-3M)
Working solutions must be 1mM ( 1 x 10-3M) in 70% methanol. Describe a serial dilution scheme
to dilute 1mL of experimental sample (it is 10mM) to a 1mM concentration in 70% methanol
D. Prepare samples for “running” through the mass spectrometer.
An appropriate starting concentration of a sample for analysis in a MS is at a concentration on the order
of 10-5M. It also requires methanol (70% to generate ions)and acid (1%, asource of protons).The
samples prepared above are 10-3M.
Prepare 5mL of each sample in the following manner
50 L of the test compound
49.5L of formic acid
1435.5L of water
3465.0L of methanol
E. Follow instructions for Advion CMS startup and operation.
Test all standards first, noting mass spectrum for each sample. These are pure substances. The spectrum will be
for 1 compound. Note however, there may be more than 1 peak due to isotopes. Since the MS provides the
mass-to-charge ratio of the sample being analyzed, the spectrum produced with have results for all isotopic
versions.
F. Analysis of an Unknown
Test experimental samples. Expected results are unknown. Compare the standard spectrum to results of the
treated aspartame samples to determine degradation products in each treatment.
1. Run the unknown (treated) samples
2. Determine possible candidate compounds based on molecular weight.
3. Use IsoPro software to determine the theoretical isotope pattern for each candidate compound
4. Compare the theoretical pattern to the experimental data.
5. Determine the identity of the degradation products from aspartame.
Mass Spectrometry for Molecular Identification
Name__________________________________________
Data and Results
Aspartame is a modified peptide composed of aspartic acid and phenylalanine methyl ester. It is about 200x sweeter
than sucrose and so can be used as a sugar substitute. However, aspartame will decompose by hydrolysis to produce a
variety of products, including aspartyl-phenylalanine, aspartic acid, phenylalanine, and phenylalanine methyl ester.
These products are not sweet. These products can be identified using electrospray ionization mass spectrometry. The
goal of this experiment was to determine under what condition is aspartame destroyed and the products that are
produced.
________ 1. What is the number of the experimental condition for which your group prepared aspartame?
Complete the following table for each of the experimental conditions
Table 1. Experimental conditions used to study the stability of aspartame.
Number Temperature Solvent
pH
Description of variable tested
o
This was the control or the condition to which all other samples were compared. It was
1
4C
water
hoped aspartame would be stable under these conditions.
o
2
22 C
water
3
170oC
water
4
4oC
citrate
4.6
5
4oC
citrate
6.2
6
4oC
phosphate 6.2
7
4oC
phosphate 8.0
2. Why not use one buffer, citrate or phosphate? Is it necessary to introduce an additional variable? Consider in your
answer the definition of a buffer._____________________________________________________________________
________________________________________________________________________________________________
________________________________________________________________________________________________
3. IsoPro is a mass spectral isotopic distribution simulator for Windows based on the Yergey algorithm. It is available as
freeware at https://sites.google.com/site/isoproms/. This program will provide the predicted spectra for a sample
when provided with its molecular formula.
Go to this site and download the simulator.
Enter the molecular formula for aspartame (C14H18N2O5). Print a copy of this spectra and include with your
report.
Repeat for a possible degradation product. (See handout)
4. Using combined class data, complete the following table
Table 2. Results of EIS-MS for aspartame samples subjected to differing conditions of storage or use
Number
1
Temperature Solvent
4o C
water
pH
Results of EIS-MSThis was the control or the condition to which all other samples were compared. We
expect only a single spectra for aspartame at molecular mass of 294. Isotopes may
provide additional results. See IsoPro results
2
22oC
water
3
170oC
water
4
4oC
citrate
4.6
5
4oC
citrate
6.2
6
4oC
phosphate 6.2
7
4oC
phosphate 8.0
5. Summarize the results in table 2. Was there evidence of aspartame degradation in conditions that varied with
temperature or pH? Indicate what products were found. Which conditions produced the greatest number of
products? The fewest?
________________________________________________________________________________________________
________________________________________________________________________________________________
________________________________________________________________________________________________
________________________________________________________________________________________________
________________________________________________________________________________________________
6. Conclusion
Is the ESI-MS an effective method for detecting degradation products of aspartame? Provide evidence to
support your answer.
Based on the results above, what are the optimal conditions in which aspartame should be stored or used in
food products? Make sure your answer includes “because…”
Why can’t aspartame be used in all kinds of foods?
What is the pH of the human stomach? The intestines? What would be the predicted degradation products of
aspartame as it passes through the human digestive system?
The use of aspartame in food is very controversial, yet it is made of two amino acids found in all proteins. Given
your knowledge of the products of aspartame degradation, which would you suggest could be harmful? Explain
why you have suggested this?
Soft drinks typically contain 180mg of aspartame. Using this value, calculate the necessary dilution of a soft
drink so that it can be analyzed in the ESI-MS. It must be 10-5M in 70% methanol and 1%formic acid.
NutraSweet
Food Additives
http://chemcases.com/nutra/nutra3.htm
Aspartame is an artificial sweetener used as a sugar substitute in some foods and beverages. Aspartame
is a methyl ester of the aspartic acid/phenylalanine dipeptide. It was first sold under the brand name
NutraSweet. Aspartame was discovered in 1965 by James M. Schlatter, a chemist working for G.D. Searle
& Company. In 1985, Monsanto Company bought G.D. Searle, and the aspartame business became a
separate Monsanto subsidiary, the NutraSweet Company. In March 2000, Monsanto sold it to J.W. Childs.
US patents on the product expired in 1992. NutraSweet is classified as a food additive, as are all similar
sweeteners. As such, NutraSweet had to clear the rigorous review process required by the FDA before its
approval for use in food for human consumption.
The sweetness of NutraSweet was noted in 1965, but it was not until 1981 that the FDA approved its use.
Part of that time span was used by the G. D. Searle company to synthesize compounds of similar structure
to determine if a closely related material might be a better sweetener, to work on the most cost-efficient
and effective manner in which to make the compound, and to protect its property interests through the
patent process. But many years were also spent testing the product as required by the FDA. In the almost
two decades since first approval, testing continues and the use of NutraSweet remains a rather
controversial issue. A trip to the Internet will reveal many anecdotal but scientifically undocumented
bulletins regarding health risks associated with the use of NutraSweet.
It is likely that the scientists at Searle were excited about the commercial prospects for aspartame when
its sweetness was accidentally discovered in 1965 because, though a synthetic material, its two principal
components were naturally occurring amino acids found in protein materials and present in foods.
Nonetheless, to bring a product to marketplace, the FDA requires several chemical and biochemical
assessments of safety.
For example, is a substance acutely toxic? In other words, will it cause an undesirable effect prior to any
chemical or metabolic breakdown in the body? Answers to this question are quite easily obtained. More
rigorous investigation requires an analysis of the metabolic fate of the product. In the stomach, where
gastric juices can act, aspartame is likely to be at least partially if not completely converted to its major
component parts, the two natural amino acids – aspartic acid and phenylalanine – and methanol. What is
the toxicity of these chemical? Finally, what is the fate of those three chemicals as they pass through the
body and undergo their metabolic changes? Again, pronounced effects would be seen immediately, but
more subtle effects might not be. Consequently, what does one investigate to assess safety? There are an
awful lot of body parts that might be affected, so it is important to establish a protocol for testing, and this
is what the FDA has done. Beyond what might be observable in an hour or a day or two is, of course, the
concern about effects that might arise from the long-term use of any product. Consequently, studies that
project the result of years of use need to be undertaken. Most studies involve test animals, often rodents,
whose metabolic processes and tendency towards various maladies (cancer, circulatory problems, etc.)
are well studied. It has never been easy, nor without great controversy, to use animal results to predict
human effects. Eventually, a human population makes itself available for testing.
As we all know, dosage will have a major effect on results. A glass of water to quench a thirst will be well
received; a gallon of water to quench the thirst will likely cause great discomfort. With a product like
NutraSweet, an optimal dose is determined by the degree of sweetness desired, but what is the risk if a
person drinks one diet soft drink a week versus one a day or one an hour? Also, is there a difference if the
person is 60 years old, 16 years old, or 6 years old? Such questions need answers before a product can be
marketed. It is not uncommon in testing the safety of a product to overdose the animal subject of the
testing. This type of study allows the establishment of a safe dose, especially by exacerbating the
development of undesired side effects at high doses. They are much easier to observe. Such tactics can
result in considerable controversy, for the argument can be advanced that though a product might cause
cancer, say, at a very high concentration, it would never be consumed at that level and that at a lower
level the product is acceptably safe. This is, in fact, the controversy that surrounded the saccharin studies
that led to the requirement of the health warning. A cancer development occurred with dosages that
were beyond a reasonable amount.
Several pharmacological studies that investigated the effects of aspartame on the endocrine, nervous,
gastrointestinal, and reproductive systems have been published. Metabolic studies confirm that
aspartame is converted to methanol and the two amino acids in the gastrointestinal tract and does not
itself enter the bloodstream unchanged. Both short- and long-term studies show no deleterious effect at a
level of minimally 2,000 mg per kg of body weight per day. When the FDA approved the use of aspartame,
it cautiously established an acceptable intake of 50 mg/kg/day. If a 12 oz. diet cola contains 180 mg of
aspartame, it is easy to calculate how many colas might be consumed, if uncomfortably, by a 150 lb.
person adhering to the acceptable intake. Although its safety is backed by considerable scientific support,
reports still circulate that aspartame may cause dizziness, headaches, and changes in the brain.
Q. Calculate the number of 12 oz. diet colas that
would be consumed by a 150 lb. person to reach
the threshold of 50 mg/kg/day. *
In addition to those whose body functions would be classified as normal, many people have metabolic
dysfunctions or allergies that might limit what nutrients can be tolerated. Since diabetics cannot tolerate
glucose, a non-sugar sweetener is a terrific alternative. But can it be tolerated? Thus, it becomes
necessary to investigate the tolerance to a substance such as aspartame in people with metabolic defects.
This has been done. Some people have an inability to metabolize phenylalanine properly
(phenylketonuria, or PKU) and must restrict their diet to exclude foodstuffs that have proteins or amino
acids rich in phenylalanine. As a source of phenylalanine, aspartame products require labeling that
adequately warns consumers. Check a label. Clinical studies suggest that even people with concerns
about phenylalanine content are not likely to consume amounts that pose a health danger, however.
Another concern is the effect that aspartame consumption might have when combined with other
foodstuffs. Might there be an unfavorable synergistic effect? Again, various studies suggest that this does
not seem to pose problems.
Finally, even though aspartic acid and phenylalanine occur naturally in many sources (as do small
quantities of methanol), do they pose an unnecessary threat to health if consumed as aspartame?
Methanol is toxic, causing blindness and death if ingested, say, in a quantity akin to the typical
consumption of ethanol, grain alcohol, the alcohol of beer and wine. But methanol consumed in the small
quantities associated with natural sources, such as fruit, or with aspartame seem quite safe. None of these
three components of aspartame bioaccumulate in the body and all are metabolized in a fashion that
produces end products harmless to human health in the quantities produced.
Since its commercial introduction in the early 1980s, aspartame has been consumed, sometimes
regularly, by millions of people. The testing alluded to in this section occurred not only prior to
aspartame’s introduction but also subsequently, and continues today. As mentioned previously, reports
of adverse effects still surface. As part of its monitoring process, the FDA has investigated such reports,
but no scientific study has ever suggested that aspartame poses any threat to the health of the general
population in any specific, identifiable manner. It appears to be a remarkably safe food additive and one
that has brought the pleasure of noncaloric sweetness to many a mouthful of food and drink.

X number of 12 oz cans = 150lbs X 0.45kg X 50mg X 1-12oz can = 18.75 cans of soda
1lb
1kg
180mg
Aspartame exposed - GM Bacteria used to create
deadly sweetener
Wednesday, January 05, 2011 by: Anthony Gucciardi
Tags: aspartame, GM bacteria, health news
Learn more: http://www.naturalnews.com/030918_aspartame_GM_bacteria.html#ixzz2Z3CG3e8L
(NaturalNews) The manufacturers of the most prevalent sweetener in the world have a secret, and it`s not a
sweet one. Aspartame, an artificial sweetener found in thousands of products worldwide, has been found to be
created using genetically modified (GM) bacteria. What`s even more shocking is how long this information has
been known. A 1999 article by The Independent was the first to expose the abominable process in which
aspartame was created. Ironically, the discovery was made around the same time as rich leaders around the
globe met at the G8 Summit to discuss the safety of GM foods.
The 1999 investigation found that Monsanto, the largest biotech corporation in the world, often used GM
bacteria to produce aspartame in their US production plants. The end result is a fusion between two of the
largest health hazards to ever hit the food industry -- artificial sweeteners and an array of genetically altered
organisms. Both have led to large-scale debate, with aspartame being the subject of multiple congressional
hearings and scientific criticism. Scientists and health advocates are not the only ones to speak out against
aspartame, however. The FDA received a flurry of complaints from consumers using NutraSweet, a product
containing aspartame. Since 1992, the FDA has stopped documenting reports on the subject.
The process in which aspartame is created involves combining an amino acid known as phenylalanine with
aspartic acid. First synthesized in 1965, aspartame requires bacteria for the sole purpose of producing
phenylalanine. Monsanto discovered that through genetically altering this bacteria, phenylalanine could be
created much more quickly. In the report by The Independent, Monsanto openly admitted that their mutated
bacteria is a staple in the creation process of aspartame.
"We have two strains of bacteria - one is traditionally modified and one is genetically modified," said the source
from Monsanto. "It's got a modified enzyme. It has one amino acid different."
Multiple studies have been conducted regarding genetic manipulation, with many grim conclusions. One study
found that the more GM corn was fed to mice, the fewer babies they had. Another study, published in the
International Journal of Biological Sciences, found that the organs that typically respond to chemical food
poisoning were the first to encounter problems after subjects consumed GM foods. The same study also states
that GM foods should not be commercialized.
"For the first time in the world, we've proven that GMO are neither sufficiently healthy nor proper to be
commercialized. [...] Each time, for all three GMOs, the kidneys and liver, which are the main organs that react
to a chemical food poisoning, had problems," indicated Gilles-Eric Seralini, an expert member of the
Commission for Biotechnology Reevaluation.
Consumer groups are now curious as to whether or not other products secretly contain genetically modified
ingredients. Due to the fact that the finished product`s DNA does not change when using genetically modified
bacteria, it is hard to know for sure. With the FDA ruling against the labeling of GM salmon, it is becoming
more of a challenge to determine whether or not a product contains GM ingredients. Consumers are voicing
their opposition for GM ingredients going incognito, with the largest growing retail brand being GMO-free
products.
"The public wants to know and the public has a right to know," said Marion Nestle, a professor in the Nutrition,
Food Studies and Public Health Department at New York University.
Unveiling the secret process in which aspartame is created acts as yet another reminder to stay away from
artificial sweeteners, and one should choose natural alternatives such as palm sugar, xylitol, or stevia.
Learn more: http://www.naturalnews.com/030918_aspartame_GM_bacteria.html#ixzz2Z3C39Nc9
Can Milk Sweetened With Aspartame Still Be
Called Milk?
by Allison Aubrey
March 06, 2013
http://www.npr.org/blogs/thesalt/2013/03/06/173618723/can-milk-sweetened-with-aspartame-still-be-called-milk
The dairy industry has a problem. Despite studies demonstrating milk's nutritional benefits, people are drinking
less and less of it.
Even children are increasingly opting for water or other low-cal options — including diet soda and artificially
sweetened sports drinks.
So how can milk — especially school kids' favorite, chocolate milk — compete in the low-cal arena? The dairy
industry has a strategy: Swap the sugar that's added to flavored milks for a zero-calorie sweetener such as
aspartame (or other options such as plant-based stevia).
Now, in order to pull this off, the dairy industry has some regulatory hoops to jump through. Currently, if dairy
producers want to add an artificial or no-cal sweetener, the resulting beverage is no longer allowed to be called
milk (it wouldn't meet the FDA's technical definition of milk).
So the dairy industry is petitioning the Food and Drug Administration to change the standard of what qualifies as
milk. The industry wants the iconic MILK label to remain on the front of the package, without any mention of the
reduced calories — or the added artificial sweeteners (at least, not on the front label). And the FDA has opened up
this petition for public comment.
"Kids don't like the term 'low-calorie,' " says Greg Miller of the National Dairy Council. "It's a turnoff."
Some school districts have banned flavored milk because of the high-calorie content. And some studies suggest that
when you take chocolate milk out of schools, consumption of milk declines. During a phone interview, Miller told
The Salt that the industry's petition is aimed at offering school districts a lower-calorie milk option that kids will
actually want to drink.
Miller says the petition does not seek to change existing regulations that require added sweeteners (such as
aspartame or stevia) to be named in the list of ingredients — usually found on the back of a container.
"We are not trying to be sneaky," Miller says.
But so far, lots of folks seem skeptical of the plan.
More than 90,000 people have joined a new online petition organized by SumOfUs.org, a consumer advocacy
group, opposing the dairy industry's petition.
And nutrition experts are weighing in, too, including Barry Popkin of the University of North Carolina at Chapel
Hill, who has studied the links between sugary drinks and obesity. If the goal is to reduce the amount of calories
that kids get from sweetened beverages, then removing sugar from flavored milk is one option, he says.
"If the option is flavored (milk) with diet (sweetener) vs. regular sugar, then diet (sweetener) is favored," he wrote
to us in an email.
But he says there's no evidence that kids need flavored milk, such as chocolate milk. "It has not been shown to
increase milk intake," he says. The dairy industry disagrees.
And the dairy industry's petition is also facing opposition from school food advocates.
"I think it's unconscionable," says school chef Ann Cooper, who's been working to reform the way kids eat at
school. She argues that parents and students will have a hard time discerning what's in the milk.
"This is nothing but a marketing ploy by the dairy industry to support milk sales," Cooper tells The Salt via email.
"We all need to let the USDA know that we oppose 'hiding' ingredients in milk as a way to increase profits for the
dairy industry!"
As a mom, I understand why parents want to know whether the chocolate milk their kids are being served at
school contains artificial sweeteners such as aspartame.
And the question lots of parents are asking is one of transparency: Can we really expect kids to read the fine print
on the back of the bottle to know what they're getting?
But Miller says if school districts were to choose to add a non-caloric sweetener to chocolate milk, parents would
not be left in the dark. School administrators would likely inform parents of the change by putting it on menus,
websites and newsletters.
What do you think?
Smart Knife Sniffs Out
Cancer Cells
by Jocelyn Kaiser on 17 July 2013, 2:00 PM |
Sharp thinking. The iKnife sucks surgical smoke into a mass spectrometer,
which then indicates whether the cut tissue is cancerous or healthy.
Credit: J. Balog et al., Science Translational Medicine (2013)
When surgeons can't determine the edges of a tumor, it's a
problem. Cut too much, and they risk hurting the patient. Cut too
little, and they may leave stray cancer cells behind. Now,
researchers have developed a surgical knife that can sniff the smoke made as it cuts tissue, almost instantly detecting
whether cells are cancerous or healthy.
The souped-up scalpel works by analyzing lipids, the fatty molecules that make up much of the cell membrane. In the past
few years, chemists have shown that ratios of certain lipids can be used to identify various biological tissues, including
tumors. But this requires first removing and preparing the tissue for a technique called mass spectrometry, which analyzes
the mass and structure of charged molecules.
Hungarian chemist Zoltán Takáts wondered if he could speed things up by directly analyzing the smoke created by the
electrosurgical knives that surgeons use to cut and cauterize blood vessels. Although the smoke is "a very nasty" tarry
mixture, Takáts says, he realized that one component is a vapor containing ionized molecules—just what mass
spectrometry needs. His team has shown that the lipid profiles identified by piping this vapor from an electrosurgical knife
to a mass spectrometer correspond to different tissue types from animals.
Now, his group at Imperial College London, together with Jeremy Nicholson, a biochemist who heads Imperial College's
department of surgery and cancer, has tested what they've dubbed the "intelligent knife," or iKnife, in the operating room.
The team collected nearly 3000 tissue samples from about 300 cancer patients' surgeries, had pathologists identify if a
sample was healthy tissue or a type of cancer, then matched up each result with the lipid profile they got by touching the
iKnife to the same sample. They showed that the iKnife could distinguish normal and tumor tissues from different organs,
such as breast, liver, and brain, and could even identify the origin of a tumor that was a metastasis, a secondary growth
seeded by a primary tumor elsewhere in the body.
The researchers next tried out the iKnife during 81 actual cancer surgeries using the 3000-sample database as a
reference. The iKnife results matched pathology lab results after the surgery for cancerous and normal tissues for nearly
all patients, the researchers report online today in Science Translational Medicine. With only a 1- to 3-second delay for an
iKnife readout, "it's real-time information" Takáts says. (Waiting for pathologists to analyze a sample can take up to 30
minutes.) That feedback could minimize the time a patient is under anesthesia and allow surgeons to work faster and
more effectively. The team's next step is to conduct clinical trials to find out if using the iKnife helps patients develop fewer
recurring tumors and live longer.
Although researchers are working on other ways to detect tumor margins in real time, those ways often require injecting a
patient with a special dye to highlight the tumor. The iKnife is simpler because the process "is no different from what
[physicians] normally do," Nicholson says. Surgeons will monitor a traffic light-like video display as they cut, he explains,
with red indicating tumor cells, green healthy tissue, and yellow something in between.
The iKnife is "cool" because it is uses "a byproduct of surgery," says biomedical engineer Nimmi Ramanujam of Duke
University in Durham, North Carolina, who uses optical imaging to detect tumor margins in tissue samples. She wonders,
however, how useful the tool will be to surgeons, who would ideally have a complete image of the tumor margins before
they cut into tissue, instead of having to feel out the tumor's edges by measuring single points with the iKnife. "The edge
of a tumor is more challenging to detect than cancer versus healthy tissue due to a mix of different tissue types, and it is
the edge that surgeons want to know about," Ramanujam says.
How Sweet it Is!
According to the U.S. Centers for Disease Control and Prevention, more than one-third of U.S. adults are obese. Obesity is a medical condition in which excess
body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and increased health problems. Obesity
is most commonly caused by a combination of excessive food energy intake and lack of physical activity. Now called an obesity epidemic, the number of obese
people continues to expand, even though the amount of physical activity expended has increased in many . Data from two U.S. health surveys suggests that
physical activity alone is not enough to combat the problem. "While physical activity has improved noticeably in most counties, obesity has also continued to rise
in nearly all counties," said lead researcher Laura Dwyer-Lindgren, from the University of Washington’s Institute for Health Metrics and Evaluation.
The obesity problem is directly related to how much Americans eat.
As a result many are trying to reduce calories in their diet, eliminating sugar if often a target. Also diabetics,(diabetes is a common illness attributed to obesity)
re unable to tolerate high levels of sugar. As a result, artificial sweeteners or other sugar substitutes are very popular products. Indeed, sometimes these are
difficult to avoid because artificial sweeteners and other sugar substitutes are found in a variety of food and beverages marketed as "sugar-free" or "diet,"
including soft drinks, chewing gum, jellies, baked goods, candy, fruit juice, ice cream and yogurt. There is ongoing controversy over whether artificial sweetener
usage poses health risks or whether the use of these products is even helpful at reducing weight. The US Food and Drug Administration is the government
agency that regulates artificial sweeteners as food additives. Food additives must be approved by the FDA, which publishes a Generally Recognized as Safe
(GRAS) list of additives. In the United States, six intensely sweet sugar substitutes have been approved for use. They are stevia, aspartame, sucralose, neotame,
acesulfame potassium, and saccharin, as well as several compounds called sugar alcohols
Just what are all these sweeteners? And what's their role in your diet? As a scientist, how might you test for these additives in food products?
Objectives:
Compare and contrast various artificial sweeteners for chemical and physical properties
Consider the features of organic compounds that make some of these compounds amenable to analysis using electrospray mass
spectrometry
Activity:
Information gathering jigsaw.
The class will be divided into six groups. Each group will be responsible for investigating information about one of six possible sugar
substitutes. Information will be shared with the class.
Note: Sweeteners may be classified as artificial sweeteners (peptide), artificial sweeteners, (chlorinated hydrocarbon), artificial
sweeteners (organic heterocyclic compound), sugar alcohol or aglycones.
Examples of Several Popular Sweeteners
Acesulfame potassium
Saccharin
A Comparison of Several Popular Sweeteners
Sweetener,
molecular
formula
Relative
Sweetness
to sucrose
Energy
content
(calories to
sucrose)
Type of
Compound
1tsp =4g
Ionizable?
Groups
available to
accept a
proton?
Sucrose
C12H22O11
MM =342g
Aspartame
Xylitol
Steviol
1
16
Carbohydrate
/disaccharide
None
How is it used?
Safety/Possible Health
Concerns
Major element in confectionery
and desserts, a food preservative
in high concentrations, a common
ingredient in many processed and
so-called "junk foods
Overconsumption of sucrose
has been linked with adverse
health effects including tooth
decay, increased risk for chronic
disease, defective glucose
metabolism, metabolic
syndrome, insulin resistance
and obesity.
Discovery/Approv
al in food
Used for centuries
in food. Prepared
from sugar cane or
sugar beets
Sweetener,
molecular
formula
Relative
Sweetness
to sucrose
Energy
content
(calories to
sucrose)
1tsp =4g
Acesulfame
potassium
Saccharin
Sucralose
Type of
Compound
Ionizable?
Groups
available to
accept a proton
How is it used?
Safety/Possible Health
Concerns
Discovery/Approv
al in food