Isotopically labelled standards for quantification
Acylcarnitines
The acylcarnitines are a homologous group of metabolites derived from the mitochondrial acyl-coenzyme A intermediates of fatty acid and
branched-chain amino acid catabolism by the action of a family of enzymes, the carnitine acyltransferases. The acylcarnitine conjugates are
vital to the transport of fatty acids across the mitochondrial membrane.
The detection of acylcarnitines in complex biological matrices may be achieved by analyzing either the native acylcarnitines or butylated
derivatives in which the free carboxylic acid group is esterified. When analyzing underivatized species, acidification of the sample will lead to
enhanced sensitivity. In both cases the acylcarnitines fragment to yield a common fragment at m/z 85, and a profile of acylcarnitines present
in the sample may be derived by performing a precursor ion scan (Precursors of m/z 85) of the unseparated mixture.
MS-MS
Acylcarnitines
Notation
Common Name
Molecular
mass / Da
Mass of
methyl ester / Da
Mass of
butyl ester / Da
164.13
179.15
221.20
d3-Free
2
d6-Free
2
167.16
182.18
224.22
d9-Free
2
170.18
185.20
227.24
d3-C2
2
206.14
221.16
263.21
d6-C2
2
209.16
224.18
266.23
d9-C2
2
212.19
227.21
269.26
d3-C3
2
220.15
235.17
277.22
d3-C4
2
234.17
249.19
291.24
H3-carnitine
Fragmentation of acylcarnitines
(Parents of m/z 85)
ELECTROSPRAY
NeoLynxTM
For research use only.
H6-carnitine
H9-carnitine
H3-acetylcarnitine
H6-acetylcarnitine
H9-acetylcarnitine
H3-propionylcarnitine
H3-butyrylcarnitine
Not for use in diagnostic procedures.
H
RCO-O
(CH3)3N
CH2
CH
CH
Butylation
H
RCO-O
(CH3)3N
CH2
CH
CH
2
254.23
269.25
311.30
d3-C8
2
290.23
305.25
347.30
d9-C14
2
380.37
395.38
437.44
d3-C16
2
402.35
417.37
459.42
H9-isovalerylcarnitine
H3-octanoylcarnitine
+
CH2
CH
CH
(m/z 85)
H9-myristoylcarnitine
H3-palmitoylcarnitine
COOC4H8H
-C4H8
-RCOOH
-N(CH3)3
CID
d9-C5
COOH
COOH
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USA Milford, MA Tel: 508 478 2000
EUROPE France Tel: 1 3048 7200
ABCDEFG
©2003 Waters Corporation January 2003
02/00483 WCH12/DAM Version 2
720000539EN
www.waters.com/micromass
MS
Fragmentation of methyl ester derivatives of acylcarnitines has also been described.
Acylcarnitine information
Molecular
mass / Da
Mass of
methyl ester / Da
Mass of
butyl ester / Da
369.29
384.31
426.36
Myristoyl carnitine
371.30
386.31
428.37
C8-DC
Subaryl carnitine
317.23
346.27
430.41
288.22
C14-OH
3-hydroxy-myristoyl carnitine
387.30
402.32
444.37
258.17
300.22
C16:1
Palmitoleyl carnitine
397.32
412.34
454.39
245.16
260.18
302.23
C16
Palmitoyl carnitine
399.33
414.35
456.40
Hexanoyl carnitine
259.18
273.20
316.25
C10-DC
Sebacyl carnitine
345.32
374.31
458.45
C5-OH
3-hydroxy-isovaleryl carnitine
261.16
276.18
318.23
C16:1-OH
3-hydroxy palmitoleyl carnitine
413.31
428.33
470.40
C8:1
Octenoyl carnitine
285.20
300.22
342.27
C16-OH
3-hydroxy palmitoyl carnitine
415.33
430.35
472.40
C8
Octanoyl carnitine
287.21
302.23
344.28
C18:2
Linoleyl carnitine
423.33
438.35
480.40
C10:2
Decadienoyl carnitine
311.21
326.23
368.28
C18:1
Oleyl carnitine
425.35
440.37
482.42
C10:1
Decenoyl carnitine
313.23
328.25
370.30
C18
Stearoyl carnitine
427.37
442.39
484.44
C10
Decanoyl carnitine
315.24
330.26
372.31
C18:2-OH
3-hydroxy linoleyl carnitine
439.33
454.35
496.40
C4-DC
Methylmalonoyl carnitine
261.15
290.19
374.29
C18:1-OH
3-hydroxy oleyl carnitine
441.35
456.37
498.42
C5-DC
Glutaryl carnitine
275.17
304.21
388.31
C12:1
Dodecenoyl carnitine
341.26
356.28
398.33
C12
Dodecanoyl carnitine
343.27
358.29
400.34
C6-DC
Adipyl carnitine
289.19
318.23
402.33
367.27
382.29
424.34
Notation
Common Name
Molecular
mass / Da
Mass of
methyl ester / Da
Mass of
butyl ester / Da
Free
Free carnitine
161.11
176.13
218.18
C14:1
C2
Acetyl carnitine
203.12
218.14
260.19
C14
C3
Propionyl carnitine
217.13
232.15
274.20
C4
Butyryl carnitine
231.15
246.17
C5:1
Tiglyl carnitine
243.15
C5
Isovaleryl carnitine
C6
C14:2
Notation
Common Name
Calculated using the atomic masses of the most abundant isotopes of the elements
except for deuterium (Ref: Pure App. Chem., 63(7) (1991) 975-90.)
12
C=12.0000000,
32
S=31.9720718,
1
H=1.0078250, 14N=14.0030740,
2
H=2.014101787, 13C=13.003355,
16
O=15.9949146,
N=15.00011
15