Organophosphorus pesticides

sample/matrix

50 ppb each in 1.5 mL saturated salt water, pH 7.2

SPME fiber

polydimethylsiloxane, 100 μm (57300-U)

extraction

20 min immersion with rapid stirring

column

5% phenyl polysiloxane, 30 m × 0.25 mm I.D., 0.25 μm (Supelco equivalent, SLB-5ms, 28471-U)

oven

60 °C (1 min) to 300 °C at 12 °C/min, hold 5 min

inj. temp.

splitless (0.75 mm I.D. liner), 270 °C

detector

MS (m/z = 45-400, 0.6sec/scan)

carrier gas

helium, 30 cm/sec