Triglyceride reference methods

European Commission. 1999. Reference method for the detection of foreign fats in milk fat by gas chromatographic analysis of triglycerides - revision 1. Commission Regulation (EC) No 2771/1999 Annex II. Official Journal of the European Communities L 333/23. 

For more than 20 years, the CDC had maintained reference methods for cholesterol, triglycerides, and HDL cholesterol... 

Reference methods are the gold standards or accuracy targets that have been developed for the more common analytes, such as cholesterol, triglycerides, LDL, and HDL cholesterol. The reference method for cholesterol is fully validated and credentialed through the National Reference System for the Clinical Laboratory. The other methods, although not formally credentialed, have been accepted by consensus. 

The equation assumes an average molecular weight of 885 g/mole (triolein) for plasma triglycerides. In addition, because of the preliminary extraction and adsorption steps, the CDC reference method measures only the glycerides, and does not include free glycerol, the so-called triglyceride blank. 

Nova-Pak C18 column in a methanol water chloroform gradient.92 Choline chloride was added to the mobile phase. One review of techniques used in the analysis of triacylglycerols lists over 300 references on separations of the triglyceride fraction of fats using nonaqueous RPLC, aqueous RPLC, argen-tation chromatography, and other chromatographic methods.93... 

The official European Community (EC) method for determination of the purity of milk fat is based on triglyceride composition as determined by GC on a packed column (EC, 1999). This is based on a formula for the composition of genuine milk fat of the type 100 = 14.197 C40 — 36.396 C42 + 32.364 C44 — e. The limit of detection varies with the adulterant fat, but is usually <5% foreign fat. A standard reference material (CRM 519) is available (Precht el al., 1998) which has been fully characterized and the triglyceride composition determined collaboratively. Other methods of analysis of the triglyceride data have been evaluated (Collomb et al., 1998a,b Lipp, 1996a,b Ulberth, 1995). 

Figure 11. Stereospecific analysis of triglycerides by the Brockerhoff method (132). The numbers 1, 2, and 3 on the glycerol symbol refer to the fatty acids at the sn-I-, sn-2-, and sn-3-positions, respectively, of the original triglyceride phenylphosphate group.

Figure 16-4 Central 95% reference interval.The 2,5 and 97,5 percentiles and their 0.90 confidence intervals of the 500 serum triglyceride concentrations (Figure i 6-3), as determined by the parametric method (see text). The curves are the estimated probability distributions.

Alkyds are made with oil contents varying from 30 to 80%. It is more accurate to refer to fatty acid content rather than oil content because the oil has ceased to exist as such after it has been reacted into the alkyd. It has been suggested that the fatty acids in 100 parts of theoretically completely esterified alkyd be calculated to triglyceride and used to define (in percent) the "oil length" or extent of oil modification. This method is of questionable value because the advent of new polyols and the increasing use of mixtures of the same to achieve special properties make it quite impossible to calculate the quantity of fatty acid ester. 

As summarized in the review by Clifford (1985b), the terms crude and total lipid refer to substances extracted by a non-polar solvent and may include non-lipid substances such as caffeine. The yield is a function of the extraction method as much as of the composition of the beans. The crude lipid includes the wax coating the coffee bean (0,2-0.3 %), the main constituents of which are the C2o and C22 amides of 5-hydroxytryptamine [l//-indol-5-ol, 3-(2-aminoethyl-), serotonine]. These amides have their importance. As they are possible antioxidants, it has been suggested that premature dewaxing leads to a fall in the bean quality during storage. The major part of the crude lipid is a typical seed oil, with triglycerides of fatty acids, some other esters and unsaponifiable matter. 

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