Solid phase extraction/programmed temperature vaporizer (PTV) injection in GC-analysis of toxaphene and PCBs in aqueous samples

Aqueous solubilities of non-ortho and mono-ortho PCBs at four temperatures

The temperature-dependent aqueous solubilities of 12 non-ortho and mono-ortho coplanar PCBs (IUPAC Nos. 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189) were determined at 5 degrees C, 15 degrees C, 25 degrees C, and 35 degrees C. A generator-column/extractor-column technique was used, followed by off-line GC/ECD analysis. The relative standard deviations for the measurements were < or = 7.4%. The determined solubilities increase exponentially with temperature from 5 degrees C to 35 degrees C for all 12 tested PCBs, and their enthalpies of solution were determined to range from 22.3 to 45.0 kJ/mol. The determined solubilities of PCB 77 at 25 degrees C were further compared with the results reported previously and with the calculated data. Within homolog groups, congeners with more ortho-substitution generally have greater aqueous solubilities. The measured aqueous solubilities of 58 congeners compiled from the literature and from this study were used for evaluation of quantitative structure-property relationships relating chlorine substitution pattern to the aqueous solubilities. A useful equation by which to estimate aqueous solubilities was derived on the basis of multi-regression analysis, which employs easily calculable molecular descriptors. The validity of this equation is demonstrated by comparison of the estimated values with experimental values. This newly developed model agrees well with log K(ow)-based model predictions.

Current developments in the analysis of water pollution by polychlorinated biphenyls

A review and discussion of the analytical developments of the last 10 years in the determination of polychlorinated biphenyls (PCBs) in water are presented, including sample treatment, clean-up, identification and determination. Some of the most significant advances have occurred in the area of sample preparation, such as the increased adoption of solid-phase extraction and on-line techniques and the chromatographic separation of PCB congeners, principally by mass spectrometry. Special attention is focused on applications to real samples.