Determination of chlorophenols, bisphenol A and 17β-estradiol by gas chromatography/negative-ion chemical-ionization mass spectrometry

An analytical method for determining potential endocrine disrupters (2,4-dichlorophenol, pentachlorophenol, bisphenol A (BPA) and 17 beta-estradiol) by GC/MS with negative-ion chemical-ionization (NICI) has been developed. The target chemicals were derivatized with pentafluorobenzyl bromide (PFBBr) and the NICI of all derivatives produced an intense (M-PFB)(-) ion as the base peak. A trace analysis of the target chemicals was carried out on GC/MS-SIM using an (M-PFB)(-) ion. The effect of the reagent gas (methane) flow rate and ion source temperature on the ion abundance was examined for the optimized GC/MS condition. These were determined as follows: reagent gas-flow rate, 2.5 ml/min; ion source temperature, 210 degrees C. The detection limits of the method ranged from 0.4 pg/ml to 12.5 pg/ml. Good linearity of the calibration curve was obtained in the concentration range from 10 pg/ml to 100 ng/ml. The correlation coefficients were > 0.9995 for all chemicals. The relative standard deviations of the peak areas of the target chemicals were 2.8 similar to 9.3% for 20 pg/ml, 6.2 similar to 9.7% for 100 pg/ml and 2.7 similar to 8.6% for 1000 pg/ml. The recoveries of the target chemicals from river water spiked with standards at the 10 pg/ml level for 17 beta-estradiol, 100 pg/ml level for chlorophenols and 1000 pg/ml level for BPA were 91.4 similar to 103.3%. The relative standard deviations were from 5.0 to 8.3%. When the detection limits of this method were compared with those obtained by electron ionization (EI) of the trimethylsilylated derivatives, the sensitivities of NICI were 6.5 similar to 150 times higher than those of EI.