Column silylation method for determining endocrine disruptors from environmental water samples by solid phase micro-extraction

In solid phase micro-extraction (SPME), the analyte is partitioned between the coating and the sample and then desorption of the concentrated analyte is followed by GC-MS, where the analytes are thermally desorbed and subsequ ently separated on the column and quantified by the detector. The SPME meth od preserves all the advantages, such as simplicity, low cost, on site samp ling and does not require solvents. Poly(acrylate) coating fibers have been developed for the extraction of phenols (such as 4-tert-butylphenol, 2,4-d ichlorophenol, 4-n-pentylphenol, 4-n-hexylphenol, 4-tert-octylphenol, 4-n-h eptylphenol, 4-n-nonylphenol, 4-n-octylphenol, pentachlorophenol and bisphe nol A) in different water samples. The precision of the HS-SPME method rang es from 3-12% RSDs, depending on the compounds analyzed. More accurate resu lts were obtained by HS-SPME with acidification and salting out, where the fiber is located above the liquid sample. The extraction period was 60 min, followed by desorption for 5 min at 300 degreesC. After the analytes were completely desorbed, 1 mul of bis(trimethylsilyl)trifluoroacetamide (BSTFA) was injected by ordinary GC-MS injection. The trimethylsilylate peaks were improved significantly compared with free phenol peaks. The addition of sa lt (saturated sodium chloride) and acidification by hydrochloric acid (pH 2 .0) were found to be very important for enhancing the partitioning of the p olar phenols into the polymer coating and preventing ionization of the anal ytes. The method is capable of limits of detection of subparts per billion of the total phenols extracted from environmental water samples. (C) 2001 E lsevier Science B.V. All rights reserved.