2000 Volume 49 Issue 5 Pages 329-336
An analytical method for the determination of potential endocrine disruptors, seven alkylphenols including nonylphenol and 4-t-octylphenol, by gas chromatography/mass spectrometry(GC/MS)with negative-ion chemical-ionization(NICI)has been developed.First, the detection limits by GC/MS-SIM with electron ionization(EI)and NICI were compared for the underivatized and pentafluorobenzyl(PFB)derivatives of alkylphenols.The NICI-SIM of PFB derivatives used an(M-PFB)- ion as the monitoring ion.The reagent gas(methane)flow rate and the ion-source temperature were determined to be 2.5ml/min and 250°C, respectively, for the optimized NICI-SIM conditions.In the case of EI-SIM, the sensitivities of PFB derivatives were 2.1∼6.3 times higher than those of underivatized target chemicals.Furthermore, the sensitivities of PFB derivatives by NICI-SIM were 67∼300 times higher than those of underivatized target chemicals by EI-SIM.The detection limits by NICI-SIM ranged from 1.0pg/ml to 33pg/ml.This method also provides good linearity of the calibration curve and repeatability.The correlation coefficients of calibration curve were >0.9995 for all chemicals in the concentration range from 1pg/ml to 10ng/ml.The relative standard deviations of the peak areas of the target chemicals were 3.6∼6.8% for 10pg/ml, 2.3∼4.9% for 100pg/ml and 2.4∼3.5% for 1000pg/ml.The recoveries of the target chemicals from a river-water sample spiked with standards at 10pg/ml levels for 4-n-pentylphenol, 4-n-hexylphenol, 4-n-heptylphenol and 4-n-octylphenol, 100pg/ml levels for 4-t-butylphenol and 4-t-octylphenol and 5000pg/ml levels for nonylphenol were 77.9∼102%.The relative standard deviations were to be from 4.1 to 12%.
