Analysis of saxitixin in urine by continuous‐flow fast‐atom bombardment mass spectromety

An improved method of saxitoxin analysis in urine using continuous-flow fast-atom bombardment mass spectrometry was developed. Parameters studied were matrix composition, matrix flow, temperature of probe tip, probe-tip design and sample extraction. Optimal detection was obtained using the following matrix composition: 5% glycerol, 0.5% acetic acid, 0.025% sodium dodecylsulfate, 0.1% polyethylene glycol (PEG) 400 and 0.5% PEG 300; probe-tip temperature: (approximately 55 degrees C); flow rate: 5 or 8 microL per min.; probe tip: Olson-Hogge design. The STX standard was detected at 200 pg with signal-to-noise ratio of 11. The percent recovery of saxitoxin from human urine after clean-up on a weak cation exchange column was 75%.