Analysis of triacylglycerol positional isomers in food products as brominated derivatives by high-performance liquid chromatography coupled with a flame ionization detection.

Reversed-phase HPLC resolution and HPLC-flame ionization detection quantitation of model triacylglycerol positional isomer pairs (important in the study of food formulation lipids) after facile conversion to brominated derivatives is reported. The positional isomers in the triacylglycerol pairs were at least 98% resolved from each other during reversed-phase HPLC. Triacylglycerol quantitation obtained by HPLC-flame ionization detector was checked against standard positional isomer pairs known by mass. The flame ionization detection area percent gave absolute error range of 0.3-1.6% per triacylglycerol.

Triacylglycerol analysis of potential margarine base stocks by high-performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry and flame ionization detection.

Several margarine base stock candidates have previously been prepared for the purpose of finding better, more oxidatively stable food components: high-saturate vegetable oils, randomized vegetable oils, vegetable oil-hard stock blends, and interesterified vegetable oil-hard stock blends. Here are reported the triacylglycerol compositions of these products, determined using reverse-phase high-performance liquid chromatography (HPLC) coupled with a flame ionization detector or a quadrupole mass spectrometer with an atmospheric pressure chemical ionization source. Triacylglycerol percent composition results for samples of known composition (randomized and interesterified samples) exhibited less average error by HPLC coupled with a quadrupole mass spectrometer with an atmospheric pressure chemical ionization source, after application of response factors, than the results by HPLC coupled with a flame ionization detector. The fatty acid compositions calculated from the mass spectrometric data exhibited less average error than the fatty acid compositions resulting from the flame ionization detector data. The average error of the fatty acid compositions by the mass spectrometer was lowest for interesterified blend samples, next lowest for randomized samples, then followed by high-saturated fatty acid oils, normal oils, and blends. Analysis of the vegetable oil-hard stock blends by mass spectrometer required special treatment for calculation of response factors.

Pentane from thermal decomposition of lipoxidase-derived products.

Thermal decomposition of 13-hydroperoxyoctadeca-9,11-dienoic acid yields hydrocarbons as part of the scission products. Pentane is formed predominately and to the practical exclusion of all other short-chain hydrocarbons.

Chromatographic silica gel: surface area determined by adsorption.

The surface area of silicic acid, a form of silica gel, has been determined by adsorption of methanol from a benzene solvent. The method is straightforward, uses inexpensive apparatus, and should be applicable to other particulate adsorbents.