Profiling neutral lipids in individual fish larvae by using short‐column gas chromatography with flame ionization detection

Abstract

The triacylglycerol (TAG) to sterol (ST) ratio, which has been used to determine the condition index in marine species, has regularly been measured via thin‐layer chromatography with flame ionization detection (TLC/FID) using the Chromarod‐Iatroscan system. However, this method is labor intensive, requires long analysis times, and has a detection limit of ~50 ng. For the determination of lipids in very small samples such as individual fish larvae, short‐column gas chromatography with flame ionization detection (GC/FID) provides an excellent alternative to Iatroscan TLC/FID, owing to its lower detection limit (~1 ng for high‐molecular‐weight TAG and ~0.1 ng for lower‐molecular‐weight species). As well, GC/FID individually profiles lipids based on their carbon number, whereas TLC/FID groups lipids according to their lipid class. Here we describe a method for the determination of neutral lipids from individual Cyclopterus lumpus (lumpfish) and Myoxocephalus scorpius (short‐horn sculpin) larvae using short‐column GC/FID. By using an internal standard and applying weight correction factors, ST and TAG can be accurately and precisely measured. The results reveal that there were no significant differences between GC/FID and TLC/FID in the quantification of TAG or ST in individual fish larvae (P > 0.05); however, GC/FID is more sensitive, precise, rapid, and cost‐efficient.