Pattern recognition for classification and determination of polychlorinated biphenyls in environmental samples

A comprehensive approach to actual polychlorinated biphenyls environmental contamination

Worldwide polychlorinated biphenyls (PCBs) pollution is due to complex mixtures with high number of congeners, making the determination of total PCBs in the environment an open challenge. Because the bulk of PCBs production was made of Aroclor mixtures, this analysis is usually faced by the empirical mixture identification via visual inspection of the chromatogram. However, the identification reliability is questionable, as patterns in real samples are strongly affected by the frequent occurrence of more than one mixture. Our approach is based on the determination of a limited number of congeners chosen to enable objective criteria for Aroclor identification, summing up the advantages of congener-specific analysis with the ones of total PCBs determination. A quantitative relationship is established between congeners and any single mixture, or mixtures combination, leading to the identification of the actual contamination composition. The approach, due to its generality, allows the use of different sets of congeners and any technical mixture, including the non-Aroclor ones. The results confirm that PCB environmental pollution in northern Italy is based on Aroclor. Our methodology represents an important tool to understand the source and fate of the PCBs contamination.

Use of fuzzy chromatography mass spectrometric (FCMS) fingerprinting and chemometric analysis for differentiation of whole-grain and refined wheat (T. aestivum) flour

A fuzzy chromatography mass spectrometric (FCMS) fingerprinting method combined with chemometric analysis has been established for rapid discrimination of whole-grain flour (WF) from refined wheat flour (RF). Bran, germ, endosperm, and WF from three local cultivars or purchased from a grocery store were studied. The state of refinement (whole vs. refined) of wheat flour was differentiated successfully by use of principal-components analysis (PCA) and soft independent modeling of class analogy (SIMCA), despite potential confounding introduced by wheat class (red vs. white; hard vs. soft) or resources (different brands). Twelve discriminatory variables were putatively identified. Among these, dihexoside, trihexoside, apigenin glycosides, and citric acid had the highest peak intensity for germ. Variable line plots indicated phospholipids were more abundant in endosperm. Samples of RF and WF from three cultivars (Hard Red, Hard White, and Soft White) were physically mixed to furnish 20, 40, 60, and 80 % WF of each cultivar. SIMCA was able to discriminate between 100 %, 80 %, 60 %, 40 %, and 20 % WF and 100 % RF. Partial least-squares (PLS) regression was used for prediction of RF-to-WF ratios in the mixed samples. When PLS models were used the relative prediction errors for RF-to-WF ratios were less than 6 %. Graphical Abstract Workflow of targeting discriminatory compounds by use of FCMS and chemometric analysis.

Chemometrics: A new scenario in herbal drug standardization

Chromatography and spectroscopy techniques are the most commonly used methods in standardization of herbal medicines but the herbal system is not easy to analyze because of their complexity of chemical composition. Many cutting-edge analytical technologies have been introduced to evaluate the quality of medicinal plants and significant amount of measurement data has been produced. Chemometric techniques provide a good opportunity for mining more useful chemical information from the original data. Then, the application of chemometrics in the field of medicinal plants is spontaneous and necessary. Comprehensive methods and hyphenated techniques associated with chemometrics used for extracting useful information and supplying various methods of data processing are now more and more widely used in medicinal plants, among which chemometrics resolution methods and principal component analysis (PCA) are most commonly used techniques. This review focuses on the recent various important analytical techniques, important chemometrics tools and interpretation of results by PCA, and applications of chemometrics in quality evaluation of medicinal plants in the authenticity, efficacy and consistency.

Congener profiles of occupational PCB exposure versus PCB exposure from fish consumption

The composition of polychlorinated biphenyl (PCB) congeners in serum samples is compared between a cohort previously exposed to PCBs from working at a capacitor plant (n=180) and a cohort of Great Lakes sport-caught fish eaters (n=217). Fourteen congeners were measured in both samples. A multiple logistic regression model differentiating the two groups as a function of relative proportions amongst congeners 74, 138, 153, 180, and 201 correctly classifies more than 99% of the people (395/397); higher proportions of congeners 74, 153, and 201 characterize capacitor plant workers, while higher proportions of congeners 138 and 180 characterize fish eaters. The pattern is driven by the relative amounts of 74+153+201 compared to 138+180; all of the fish eaters, but only 5% of the capacitor plant workers, have a greater percent of 138+180 than 74+153+201. Consideration of combinations of congener levels and their relative proportions is relevant to tracking route of exposure and may also be relevant to modeling effects on health outcomes.

Fingerprinting PCB patterns among Mohawk women

This study examined the association of contaminated fish consumption and polychlorinated biphenyl (PCB) body burden by comparing the similarity of the congener pattern in yellow perch, caught near the point source of industrial pollution, and in other local fish to the pattern found in the breast milk of Mohawk women from Akwesasne, a Native American community located along the St. Lawrence River in New York, Ontario, and Quebec. The similarity is defined by the weighted Euclidean distance between two congener patterns. Ninety-seven Mohawk mothers participated and provided samples of breast milk. One hundred fifty-four nursing women from the Supplemental Nutrition Program for Women, Infants and Children (WIC) of Warren and Schoharie counties, New York, who gave birth during the same time period, were used as the comparison group. Results revealed that the breast milk of the Mohawk women, who ate the most local fish, had a congener pattern that more closely resembled that of perch caught near the waste site or average sampled fish caught in the Reserve than Mohawk women who ate less fish or the controls. The outcome demonstrates how PCBs may be "fingerprinted" as they migrate offsite from industrial sources and ultimately result in human exposure.

Influence of polychlorinated biphenyls on the growth of chicken embryos

Incubation of chicken embryos with either 0.01 or 0.03 ppm polychlorinated biphenyls (PCBs) for 12, 15, or 18 d resulted in a significant decrease in liver and body weight associated with enhanced mortality. Teratological examination revealed an increased frequency of malformations including hydrops, eventration, wry neck, and brevicollis. PCB exposure was also found to produce histologic damage to liver and cutaneous tissue. Our data demonstrate that exposure of chicks to PCBs during development results in a retardation of growth, an increased incidence of malformations, and histopathologic damage.

The determination of polychlorinated biphenyl residues: a review with special reference to foods

The determination of polychlorinated biphenyls presents several unique analytical problems, not least of which is the need to identify and quantify 209 possible analytes. Moreover, congener-specific analysis is essential because of structure-activity effects on toxicity and environmental stability. Although significant advances have been achieved in identification/quantification procedures with the aid of highly efficient, inert open tubular chromatography columns and coupled GC-MS, sampling and extraction procedures have not developed to the same extent. The primary focus of this review is the determination of polychlorinated biphenyls in foods. However, the problems of separation and identification overshadow the importance of the sample matrix, and relevant data from other areas of analysis are quoted.

Determinations of polychlorinated biphenyl isomers by response factor calibration

Quantitative measurement of polychlorinated biphenyl (PCB) isomers by response factor calibration (RFC) is evaluated with gas chromatography and the Hall electrolytic conductivity detector. The procedure requires neither isomer identification nor reference compounds identical to each measured PCB isomer. Weight percent chlorine is determined for five Aroclor mixtures by RFC and compared within a few percent of expected values. Individual PCB isomers are measured and quantitatively compared for Aroclor mixtures. Also, RFC determinations for ten PCB isomers contained in a test material reference solution are compared to the supplier's stated concentrations. These RFC measurements provide quantitative analyses in the absence of a standard for each measured component.