Abstract: Rapid evaporative ionization mass spectrometry (REIMS) was employed for lipidomic profiling of Patagonian toothfish, a kind of low-fat fish. The instrumental parameters were optimized using response surface methodology with a Box-Behnken design as follows: power output 25 W, cutting speed was 0.50 mm/s, and cutting length 1.0 cm. Under these optimized conditions, a total of 17 fatty acid molecular species were detected, among which the signal intensity of m/z 327.23 (FA 22:6, 17.81%) was the highest, followed by m/z 255.23 (FA 16:0, 9.81%), and m/z 281.25 (FA 18:1, 9.09%). A total of 10 phospholipid molecular species were tentatively identified in the m/z range from 736.49 to 909.55. The peak at m/z 885.55 was the most intensive with a relative content of 19.30%, which was identified as phosphatidylinositol (PI) species [PI 38:4–H]–, followed by phosphatidylethanolamine (PE) species at m/z 790.54 ([PE 40:6–H]–, 15.24%). The method was validated and the results showed that the signal-to-noise ratios of the target ions were in the range of 35.4–95.3, with error values of 4.17 × 10-6–9.78 × 10-6. The relative standard deviations (RSDs) of intra-day and inter-day precision were 3.7%–5.6% and 5.9%–7.3%, respectively. The results indicate that this method is sensitive and stable with high resolution. It provides a totally new technology for lipidomic and bioinformatics analysis of fish.

Key words: iKnife, rapid evaporative ionization mass spectrometry (REIMS), lipidomics, Dissostichus eleginoides