Determination of Polychlorinated Biphenyls in Marine Sediments by Ultrasound-Assisted Isolation and Dispersive Liquid–Liquid Microextraction and Gas Chromatography–Mass Spectrometry

Strategies of dispersive liquid-liquid microextraction for coastal zone environmental pollutant determination

Coastal zone means the interface of land and sea, and therefore, environmental pollutants steaming from land-based activities (like manufactories) and sea-based activities (like shipping) are all existing in coastal zone. These pollutants usually have characteristics of low residues, complicated matrices, easy accumulation and so on, causing difficulty to detect coastal pollutants quickly and sensitively. It is imperative to perform effective sample preparation prior to instrumental analysis. Dispersive liquid-liquid microextraction (DLLME) has attracted significant research interest for sample preparation, owing to its high enrichment ability, low reagent/sample consumption, and wide analyte/matrix applicability, as well as robustness, simplicity, rapidity and inexpensiveness. Herein, we comprehensively review the recent advancements of DLLME technology and its analytical parameters including enrichment principles, extraction modes, and practical application; the emphasis is on novel mode-construction and representative coastal-environmental pollutants extraction. Construction strategies are highlighted by classifying DLLME into five major modes, according to extractant's types, including normal ones, low density solvents, ionic liquids, deep eutectic solvents and others. The coupling of DLLME with other extraction techniques like solid-phase extraction is also briefly introduced. The strengths and weaknesses of each strategy and its rationality are also elaborated. In addition, some typical applications of the different DLLME modes for the determination of organic compounds and heavy metals in coastal water, sediment, soil, and biota are summarized. The increasingly concerned green aspects and instrumentation of DLLME are presented, and finally, the challenges and perspectives of the DLLME for environmental analysis are proposed.

Determination of the Polychlorinated Biphenyls Distribution in Different Fat Tissues of Cattle by Age and Gender

Polychlorinated biphenyls (PCBs), which cause environmental pollution, are found in animal-based fatty foods. Due to their long half-life and lipophilic properties, they can accumulate in the fat tissues of cattle. The study was conducted to compare the PCB levels (PCB28, 52, 101, 118, 138, 153, and 180) in the different fat tissues (muscle, liver, kidney, spinal cord, lung, back fat, perihepatic fat, and perirenal fat) of cattle by age and gender. This information is also useful to evaluate the exposure risks for different bovine edible tissues. Therefore, 15 female and 15 male cattle under 24 months of age and 15 female and 15 male cattle over 24 months of age were used, and 480 samples were analyzed for target PCBs using gas chromatography-mass spectrometry. Of all the samples, two (50.2 µg/kg in perihepatic fat and 51.1 µg/kg in kidney) were found above the maximum residue limit; these samples were taken from the animals in the elderly female group (over 24 months). There were more PCBs in cattle older than 2 years. Muscle, kidney, and perihepatic fat presented higher PCB concentrations than other tissues, and perirenal fat presented lower PCB concentrations than other tissues. PCB101, PCB153, and PCB138 were found to have the highest contribution to the PCB concentration. Thus, it is concluded that perihepatic fat, muscle, or kidney should be sampled, particularly in routine residue monitoring, and specifically analyzed for PCB101, PCB153, and PCB138.

Direct and fast determination of polychlorinated biphenyls in contaminated soils and sediments by thermal desorption-gas chromatography-tandem mass spectrometry

A direct procedure based on thermal desorption-gas chromatography-tandem mass spectrometry (TD-GC-MS-MS) was developed for the fast extraction of seven polychlorinated biphenyls (PCBs) from sediments and soils. PCBs were directly extracted, from 20 to 75 mg of sample, without any chemical pre-treatment or use of organic solvents, after the addition of 10 µL internal standard (PCB 195) in acetone. Sample treatment was totally automated. PCBs were extracted at 250 °C for 20 min, using a helium flow and the PCBs were trapped in a cryogenic Tenax trap at -10 °C. After that, analytes were directly desorbed at 270 °C and introduced to the GC-MS-MS system. Recoveries were established using spiked soil and sediment from 2.5 to 50 ng g^-1, obtaining values from 74 to 127%. The limits of quantification were from 1.0 to 1.7 ng g^-1 for soil and from 0.3 to 0.4 ng g^-1 for sediments, respectively. Precision, assessed as the relative standard deviation (RSD), was lower than 8 and 11% for sediment and soil analysis, respectively, except for PCB-28 in soil samples which provided a RSD of 18%. Certified reference material and field samples were analysed by the proposed TD-GC-MS-MS method. Results were compared by a paired samples Student's t-test with those obtained by a reference extraction procedure based on pressurized solvent extraction, followed by stir bar sorptive extraction, being statistically comparable (α = 0.05). A comprehensive greenmetric evaluation of the proposed method was carried out, having the TD extraction a negligible environmental impact as compared to conventional extraction procedures.

Selected persistent organic pollutants levels in the Ankara River by months

Persistent organic pollutants (POPs) are banned in almost all countries due to their adverse health effects while they are still present in the environment due to their persistence. As the dissipation and the emission factors of POPs change by temperature and other environmental factors current study aimed to determine selected POPs, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) in water and sediment samples collected from 12 stations located in Ankara River, Turkey, for 12 months. C-18 solid-phase extraction technique was used to extract organic pollutants and the analysis were performed using a validated gas chromatography-mass spectrometry method. DDE was the most frequently detected contaminant in water samples. Even though no PCB residues were present in water samples, PCB101 was the most common contaminant in sediment. Although both matrices had the least load of pollutants in winter, there was an increase in presence and concentration of pollutants from late spring to autumn.