[Preparation of samples for gas-chromatographic determination of fatty acids: direct transesterification of lipids of dry biological sample is preferred in comparison with the methods employing preliminary lipid extraction.].

Different methods of sample preparation and derivatization were compared from the point of view of product yield, speed and convenience of the technique used. Fatty acid determination in absolutely dry objects (biochemical preparations, food protein isolates, lyophilized microbial biomass) may be performed easily with the use of Folch method provided that 4-component system "chloroform/ methanol/water/acetic acid" was employed. Nevertheless, we ould not find any real advantages of classical Folch or Hara-Radin extraction method variants when compared to simple non-extraction technique (which consists in direct trans-esterification of dried biomaterial due to sequential sample treating with sodium methoxide and boron trifluoride methanolic solutions). The letter method, being completely universal, provides considerable increase of fatty esters yield, sample preparation is noticeably simplified and accelerated (becoming much more economical). It's "dry blood spot" variant (using cellulose or, preferably, fluoroplast filter paper disks) seems to be extremely convenient for laboratory routine analysis of liquid biological samples, allowing to exclude not only their liquid-liquid extraction but also the stage of vacuum drying. Unlike the methods of Folch and Hara-Radin, the non-extraction method does not necessarily require the homogenization of the biological material, that is, it's grinding to fragments of micron size. Direct derivatization method provides noticeably better parameters of fatty acids yield even for relatively large particles - 0.2-1.0 mm - of the test material (in comparison with those parameters observed upon extraction of micron size homogenizates by the Folch method in its most advanced modifications).