Abstract:

To analyse the impurity of bacterium source of standard endotoxin, 3-hydroxy fatty acid species in different endotoxin standards was determined by gas chromatography/mass spectrometry (GC/MS) using N,O-bis(trimethylsilyl)trifluoroacetamide as the silanizing reagent. GC/MS analysis was performed using a gas chromatograph equipped with a 60 m×0.25 mm i.d. DB-5 fused silica capillary column and an injector at 250 ℃. Helium was used as the carrier gas under a constant pressure of 206 kPa. The oven was programmed at a rate of 5 ℃/min from 90 ℃ (held for 5 min) to 280 ℃(held for 5 min). The sample size was 1 μL. The transfer line was kept at 280 ℃. The quadrupole mass spectrometer was operated in electron impact (EI) ionization mode, and the temperature of the source was kept at 250 ℃. The kind of 3-hydroxy fatty acids in 9000 EU/tube national standard endotoxin, 20 EU/tube working standard endotoxin, escherichia coli, pseudomonas aeruginosa and deionized water were determined to study the purity of bacterium source of the standard endotoxin. It was shown that 9000 EU/tube endotoxin standard and escherichia coli only contained 3-hydroxytetradecanoic acid. There was 3-hydroxydodecanoic acid in 20 EU/tube working standard endotoxin, which indicated the presence of impurity of bacterium source.

Key words: 3-hydroxy fatty acids, endotoxin standard, escherichia coli , mass spectrometry (MS), gas chromatography (GC)