Gc 2025 gas chromatograph

The extent of lipid contamination in protein pellets, following various purification methods, was measured by accounting for the sum of fatty acid methyl esters (FAMEs), obtained by methanol transesterification. The transesterification protocol was originally adopted from [46 (link)]. and modified in our lab by [47 (link)]. FAME profiles were analyzed on a GC-2025 gas chromatograph from Shimadzu (Nakagyo-ku, Kyōto, Japan) with flame ionization detector. One microliter sample was applied by AOC-20i auto injector (Shimadzu) onto a ZB-WAX column (30 m, 0.32 mm ID; 0.25 μm df; phenomenex (Torrance, CA, USA)). The initial column temperature was 150 °C (maintained for 1 min). A temperature gradient was applied from 150–240 °C (5 °C min⁻¹), followed by 6 min maintenance at 240 °C. Fatty acids were identified according to retention times of the authentic standard: Marine Oil FAME Mix (Restek, USA). Individual FAME concentrations were based on peak areas relative to Methyl Nonadecaanoate C19 (Sigma, Germany), which was incorporated as an internal standard in all samples. Percent lipid was calculated from the sum of individually identified FAMEs with respect to pellet dry weight.

According to the European Regulation (EEC 2568/91), the composition of fatty acids of the mixtures was determined as previously described by gas chromatography (GC) [50 (link)]. Briefly, the chromatographic separation was performed using a Shimadzu GC-2025 gas chromatograph (Shimadzu; Kioto, Japan). This chromatograph was equipped with a ZB-FFAP capillary column (50 m × 0.32 mm × 0.50 µm) (Phenomenex; Torrance, CA, USA), an AOC-20i autosampler (Shimadzu; Kioto, Japan) and a FID detector. Supelco 37 Component FAME Mix (Merk; Dramstadt, Germany) was used as standardized fatty acid mix to identify the peaks of each fatty acid within the samples. Percentage (%) of each fatty acid peak with respect to total quantified oil was used to express the results.