Fast Mineral Oil
Analysis using LTM
Matthew S. Klee, Ph.D.
Agilent Technologies
Wilmington, Delaware, USA
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5990-4851EN
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Mineral Oil Analysis
(HOI: hydrocarbon oil index)
• Mineral Oil analysis is in top 5 of current
environmental analyses (next to VOCs, PAHs,
pesticides)
• Analysis is done by GC-FID
(replaces old extraction – FTIR analysis)
• Technique is similar to “TPH” (Total Petroleum
Hydrocarbon) analyses done in the U.S.A.
... #1 LTM application in U.S.A.
Ref: ISO 9377-2, ISO 9377-4, EN 14039, DIN H53,…
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What is included in “Mineral Oil” analysis?
Any mixture of compounds that:
1. are extracted by hydrocarbon solvent (from soil or
water)
2. are not adsorbed by Florisil (used for cleanup)
3. elute from an apolar column between decane
(C10) and tetracosane (C40)
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Typical HOI analytical procedure
1. Extract
Water: extract 1 L water with hexane
Soil:
extract by ASE
2. Clean-up
Florisil (removes polar and semi-polar solutes such as
sterols and lipids)
3. Concentrate to 1 mL
N2 purge
4. Analyze extract by “discrimination free” injection, GCFID, area sum between C10 and C40
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Analytical requirements
Non-discriminatory injection:
– COC
• concerns about dirty samples
– PTV
– SSL (splitless)
• concerns about discrimination against high boilers
Low bleed column
– Must elute C40 (thin film, high phase ratio)
– Needs to separate solvent and 1st peak (decane)
• can be problematic with splitless injection (wide solvent peak), so low
initial temperature is required
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Typical GC-FID conditions
Agilent S/Sl:
1 µL injection in SL mode
Others:
COC or PTV (if S/Sl discriminates)
Column:
5-25 m x 0.25-0.53 mm ID
0.1-0.5 µm HP-1 or HP-5
35-40°C init to 300-350°C
Current disatisfier:
Cycle time
(~ 20-30 min without cool-dow)
Limited ramp rate or lab GCs
Cool-down time
7
80
4.207
pA
90
70
15 m x 0.53 mm id x 1.5 µm HP-1
He: 7.4 mL/min, constant flow
35°C (1.5 min) → 60°C@ 5°C/min
→ 350°C (5 min) @ 15°C/min
22.535
Typical Hydrocarbon Index Analysis by GC
(Application note 5988-0621EN)
13.331
60
50
40
30
20
10
5
8
10
15
20
25
min
“LTM” (Low Thermal Mass) Directly Heated
Column Technology (Patented)
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LTM System Installed on 7890A
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The LTM Advantage
• Total cycle time for an analysis can be cut by a factor of 3 or
more (compared to same columns in air oven and LTM)
• 1-4 independent column modules per GC
– Dual column module configurations allow simultaneous
parallel analyses
– Each module can have a different column type
– Temperature programs for modules are independent
• Compatible with CFT devices for splitting, multidimensional
separations, and/or for backflush
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LTM method 1 (hot splitless)
1 µL splitless injection, 320°C
GC oven: 340°C
FID: 340°C
LTM: 10 m x 0.32 mm ID x 0.1 µm DB-5HT
• 40°C (0.5 min) → 240°C @ 200°C/min → 340°C (0.5 min)
@ 100°C/min (3 min total)
Carrier: He
• 120 kPa (0.5 min) → 160 kPa @ 40 kPa/min → 180 kPa
(0.5 min) @ 20 kPa/min
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n-Alkane test mixture
Response
2800000
C10
2400000
C20
2000000
1600000
C40
1200000
800000
400000
0
Time
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0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
2.40
2.60
2.80
n-Alkane test mixture
Retention time repeatability (n=6)
• C10: tR = 0.812 min, s = 0.001 min, RSD = 0.06%
• C20: tR = 1.501 min, s < 0.001 min, RSD < 0.01%
• C40: tR = 2.633 min, s = 0.003 min, RSD = 0.10%
Peak Area repeatability
• C10: mean area = 4265145, RSD = 0.86%
• C20: mean area = 4578586, RSD = 1.05%
• C40: mean area = 4117178, RSD = 0.85%
Discrimination test
• Relative peak area C40/C20 = 0.899 (RSD: 1.31%)
(criterion: > 0.80)
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Calibration diesel/motor oil 400 mg/L
Response
2800000
Diesel
2400000
2000000
1600000
1200000
Motor oil
800000
400000
0
Time
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0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80
Mineral Oil calibration
Calibration from 40 – 1000 mg/L
Linearity: r² > 0.999
Repeatability at 400 mg/L:
• RSD on peak area = 0.64%
LOD: < 25 mg/L
1200
R2 = 0.9991
Area (x10 -6)
1000
800
600
400
200
0
0
200
400
600
mg/L
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800
1000
1200
Calibration 100 mg/L
Response
550000
450000
350000
250000
150000
50000
Time
17
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
2.40
2.60
2.80
Extra benefit: sensitivity gain
Response_
Signal: SENS-TEST07.D\FID1A.ch
Signal: SENS-TEST05.D\FID1A.ch (*)
2800000
2600000
2400000
2200000
3 min run
2000000
1800000
21 min run
1600000
1400000
1200000
1000000
800000
600000
400000
200000
0
0.00
Time
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2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
HOI analysis with LTM - conclusions
• Sample analysis cycle time is reduced to 5 min!
• Analysis time: 3 min
• Cool-down time to 40°C < 2 min
• Meets all method requirements with hot splitless
and Agilent ALS
• Excellent repeatability, linearity
• High sensitivity (“signal compression”)
• Dual column module configuration with
simultaneous injection and parallel analyses will
maximize throughput
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Thank you for you
interest.
Questions?
This information is subject to change without notice.
© Agilent Technologies, Inc. 2010
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