Wc. Byrdwell et al., QUANTITATIVE-ANALYSIS OF TRIGLYCERIDES USING ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION MASS-SPECTROMETRY, Lipids, 31(9), 1996, pp. 919-935
Atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) w
as used for quantitative analysis of triglycerides (TG) separated by r
everse-phase high-performance liquid chromatography. APCI-MS was used
for analysis of mono-acid TG standards containing deuterated internal
standard, of a synthetic mixture of heterogeneous TG, of randomized an
d normal soybean oils and of randomized and normal lard samples. Quant
itation of the TG by four approaches based on APCI-MS were compared, a
nd these were compared to quantitation obtained using liquid chromatog
raphy (LC) with flame-ionization detection (FID). The APCI-MS methods
were based on (i) calibration curves from data for mono-acid TG standa
rds, (ii) response factors obtained from a synthetic mixture of TG, (i
ii) response factors calculated from comparison of randomized samples
to their statistically expected compositions, and (iv) response factor
s calculated from comparison of fatty acid (FA) compositions calculate
d from TG compositions to FA compositions obtained by calibrated gas c
hromatography (GC) with FID. Response factors derived from a synthetic
mixture were not widely applicable to samples of disparate compositio
n. The TG compositions obtained using APCI-MS data without application
of response factors had average relative errors very similar to those
obtained using LC-FID. Numerous TG species were identified using LC/A
PCI-MS which were undetected using LC-FID. Two quantitation methods, b
ased on response factors calculated from randomized samples or on resp
onse factors calculated from FA compositions, both gave similar result
s for all samples. The TG compositions obtained using response factors
calculated from FA compositions showed less average relative error th
an was obtained from LC-FID data, and were in good agreement with pred
icted compositions for the synthetic mixture and for randomized soybea
n oil and lard samples.