Comparison of Spot and Time Weighted Averaging (TWA) Sampling with SPME-GC/MS Methods for Trihalomethane (THM) Analysis

Novel method in emerging environmental contaminants detection: Fiber optic sensors based on microfluidic chips

Recently, human industrial practices and certain activities have caused the widespread spread of emerging contaminants throughout the environmental matrix, even in trace amounts, which constitute a serious threat to human health and environmental ecology, and have therefore attracted the attention of research scholars. Different traditional techniques are used to monitor water pollutants, However, they still have some disadvantages such as high costs, ecological problems and treatment times, and require technicians and researchers to operate them effectively. There is therefore an urgent need to develop simple, inexpensive and highly sensitive methods to sense and detect these toxic environmental contaminants. Optical fiber microfluidic coupled sensors offer different advantages over other detection technologies, allowing manipulation of light through controlled microfluidics, precise detection results and good stability, and have therefore become a logical device for screening and identifying environmental contaminants. This paper reviews the application of fiber optic microfluidic sensors in emerging environmental contaminant detection, focusing on the characteristics of different emerging contaminant types, different types of fiber optic microfluidic sensors, methodological principles of detection, and specific emerging contaminant detection applications. The optical detection methods in fiber optic microfluidic chips and their respective advantages and disadvantages are analyzed in the discussion. The applications of fiber optic biochemical sensors in microfluidic chips, especially for the detection of emerging contaminants in the aqueous environment, such as personal care products, endocrine disruptors, and perfluorinated compounds, are reviewed. Finally, the prospects of fiber optic microfluidic coupled sensors in environmental detection and related fields are foreseen.

Alternative Ecosorbent for the Determination of Trihalomethanes in Aqueous Samples in SPME Mode

A new sorbent material based on modified clay with ionic liquid immobilized into an agarose film was developed as part of this study. It was applied to determine organochlorine pollutants, like disinfection byproducts, through headspace solid-phase microextraction-gas chromatography-electron capture detection (HS-SPME-GC-ECD). The disinfection byproducts determined in this study were used as model molecules because they were volatile compounds, with proven severe effects on human health. Their presence in aquatic environments is in trace concentrations (from pg L^-1 to mg L^-1). They are classified as emergent pollutants and their determination is a challenge for analytical chemists. The parameters which affected the extraction efficiency, i.e., number and distance between SPME discs, salt concentration, the temperature of extraction, extraction time, and desorption time, were optimized. A wide linear dynamic range of 10-1000 ng mL^-1 and coefficients of determination better than 0.997 were achieved. The limits of detection and the limits of quantitation were found in the ranges of (1.7-3.7) ng mL^-1 and (5.6-9.9) ng mL^-1, respectively. The precision, expressed as relative standard deviation (RSD), was better than 8%. The developed sorbent exhibits good adsorption affinity. The applicability of the proposed methodology for the analysis of trihalomethanes in environmental and water samples showed recoveries in the range of 86-95%. Finally, the newly created method fully complied with the principles of green chemistry. Due to the fact that the sorbent holder was made of agarose, which is a wholly biodegradable material, sorbent clay is a widespread material in nature. Moreover, the reagents intercalated into the montmorillonite are new green solvents, and during the whole procedure, low amounts of organic solvents were used.

Combining graphite with hollow-fiber liquid-phase microextraction for improving the extraction efficiency of relatively polar organic compounds

In this study, we have developed a simple and effective hybrid extraction method based on the incorporation of raw carbon nanosorbents and octanol in the pores of a hollow-fiber membrane for improving the extraction efficiency of relatively polar organic compounds. Trihalomethanes (THMs) were used as model analytes. Three types of carbon nanosorbents (graphite, graphene, and multi-walled carbon nanotubes) were studied. The carbon sorbent incorporating membrane was used in a two-phase mode liquid-phase microextraction, with 1-octanol as the acceptor solution. Using a graphite-reinforced hollow-fiber membrane and an extraction time of 10 min, enrichment factors of 40-71 were obtained for trichloromethane, bromodichloromethane, bromoform, and chlorodibromomethane. Linear working ranges of 0.2-100 μg L^-1 and limits of detection ranging from 0.01 μg L^-1 (for CHCl₂Br and CHClBr₂) to 0.1 μg L^-1 (for CHCl₃) were achieved. The minimum detectable concentrations were far below the maximum concentration levels (60-200 μg L^-1) set by the WHO for drinking water. The carbon-sorbent-reinforced hollow-fiber liquid-phase microextraction afforded higher extraction efficiency and shorter extraction time compared with conventional hollow-fiber liquid-phase microextraction. Finally, the method was applied to the analysis of real water samples, such as drinking water, tap water, and swimming pool water samples.