Micropollutants In Samples Research Articles

Is it the appropriate syringe filter? The loss of PPCPs during filtration by syringe filter

Syringe filters are used to separate solids from liquids before chromatography analysis for the removal of particulate matter to avoid column blockage. The inappropriate selection of syringe filters may lead to the interception of micropollutants in samples (especially aqueous phase samples) and inaccurate quantification. In this study, mass losses of typical micropollutants - pharmaceutical and personal care products (PPCPs) - by syringe filters were evaluated considering the material of syringe filters, the pore size of syringe filters, solvents, and pre-rinsing. The lowest mass losses of 57 PPCPs were observed by hydrophobic- polytetrafluoroethylene (PTFE) (median value was 10%), but for quinolone (7-37%) and macrolide antibiotics (9-52%), the mass losses were still considerable. By changing the pore sizes of filters, the interception of quinolone and macrolide antibiotics by hydrophobic-PTFE was not improved. In contrast, by increasing the proportion of methanol in the solvent and discarding the first 1 mL pre-rinsing samples, the mass losses of quinolone and macrolide antibiotics by hydrophobic-PTFE can be considerably decreased. This study provides guidance for selecting appropriate filters for micropollutants before chromatography analysis of samples to guarantee the accuracy of the results.

GC×GC Quantification of Priority and Emerging Nonpolar Halogenated Micropollutants in All Types of Wastewater Matrices: Analysis Methodology, Chemical Occurrence, and Partitioning.

We report the development and validation of a method to detect and quantify diverse nonpolar halogenated micropollutants in wastewater treatment plant (WWTP) influent, effluent, primary sludge, and secondary sludge matrices (including both the liquid and particle phases) by comprehensive two-dimensional gas chromatography (GC×GC) coupled to micro- electron capture detector (μECD). The 59 target analytes included toxaphenes, polychlorinated naphthalenes, organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and emerging persistent and bioaccumulative chemicals. The method is robust for a wide range of nonpolar halogenated micropollutants in all matrices. For most analytes, recoveries fell between 70% and 130% in all matrix types. GC×GC-μECD detections of several target analytes were confirmed qualitatively by further analysis with GC×GC coupled to electron capture negative chemical ionization-time-of-flight mass spectrometry (ENCI-TOFMS). We then quantified the concentrations and apparent organic solid-water partition coefficients (Kp) of target micropollutants in samples from a municipal WWTP in Switzerland. Several analyzed pollutants exhibited a high frequency of occurrence in WWTP stream samples, including octachloronaphthalene, PCB-44, PCB-52, PCB-153, PCB-180, several organochlorine pesticides, PBDE-10, PBDE-28, PBDE-116, musk tibetene, and pentachloronitrobenzene. Our results suggest that sorption to dissolved organic carbon (DOC) can contribute substantially to the apparent solids-liquid distribution of hydrophobic micropollutants in WWTP streams.

Novel gas chromatography–mass spectrometry database for automatic identification and quantification of micropollutants

A novel gas chromatography–mass spectroscopy (GC–MS) database for identification and quantification of micropollutants in environmental and food samples is reported. GC retention times, calibration curves, and mass spectra of nearly 700 chemicals were registered in the database, and the GC retention times of registered chemicals in actual samples were predicted from the retention times of n-alkanes measured before sample analysis. Differences between predicted and actual retention times were less than 3 s, an accuracy that is nearly identical to that obtained by analysis of standard substances. After the retention times were predicted, a calibration file for the GC–MS instrument was created from the predicted retention times, calibration curves, and mass spectra of the registered chemicals. With the resulting calibration file, automated identification of all the chemicals in actual samples was possible without the use of standards, and the identification method was as reliable as conventional methods. When the GC inlet, column, and tuning conditions were adjusted using GC–MS performance check standards, relative standard deviations of 20% or less for determination values could be obtained. More than 90% of the chemicals in the database could be detected at a sensitivity sufficient for all practical purposes (100 pg or less). Because each chemical in the database, to which new substances can easily be added, can be determined in 1 h, micropollutants in samples can be analyzed efficiently and inexpensively.

Gas chromatographic determination of organic micropollutants in samples of sewage sludge and compost: Behaviour of PCB and PAH during composting

A simple method for a simultaneous gas chromatographic determination of polyclorobiphenyls and polycyclic aromatic hydrocarbons in samples of sewage sludge and compost is described. Certified materials were used for the evaluation of the method. Organic micropollutants were extracted from freeze-dried samples through a mixture of organic solvents - n-hexane/dichloromethane, 4:1 v:v-in a sonification bath. A multilayer clean-up/ separation column was used to remove interfering organic compounds and to divide PCBs and PAHs into two distinct fractions; and additional purification with metallic mercury was necessary to eliminate sulphur. Fractions are quantifiable with GC-ECD and GC-MS-SIM. The method was applied to determine the concentrations of both PCBs and PAHs during the composting process; a characteristic time profile was traced.

Hydrophobic organic micropollutants in samples of coastal waters: efficiencies of solid-phase extraction in the presence of humic substances

Solid-phase extraction (SPE) has been used to enrich organic micropollutants (hydrophobic chlorinated and polycyclic aromatic hydrocarbons, CHC and PAH) from coastal water samples and to systematically study the influence of humic substances (HS) on SPE. A reversed phase (RP) system with high flow rates (rapid chromatography, RC) was used to show the basic adsorption principles and interaction processes which influence the enrichment of organic compounds. A model humic substance was found to hinder the enrichment of individual hydrophobic micropollutants (MP), depending on their octanol-water distribution coefficient POW. This effect was found to be lower with natural humic substances. For longer contact time between water sample and adsorption material, the pollutant/humic substance bonding proved to be reversible.