Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry

Efficient trihalomethane quantification in drinking water for minimally-equipped water treatment plants labs

Chlorine is a common disinfectant used in water treatment. However, its reaction with organic matter can lead to the formation of harmful byproducts, such as trihalomethanes (THMs), which are potentially carcinogenic. To address this issue, the aim of this work was to enhance a colorimetric method capable of quantifying THMs in drinking water through UV/Vis Spectrophotometry, using cost-effective equipment, and validate this methodology for the first time according to established validation protocols. The method's innovation involved replacing the solvent pentane with the more common hexane, along with adjusting the heating ramp, elucidating the mechanisms involved in the process. This method involves the reaction between THMs, pyridine, and NaOH to produce a colored compound, which is then monitored through molecular absorption spectroscopy in the visible region. The method was thoroughly validated, achieving a limit of detection of 13.41 μg L-1 and a limit of quantification of 40.65 μg L-1. Recovery assays ranged from 86.1 % to 90.7 %, demonstrating high accuracy. The quality of the linear fit for the analytical curve exceeded R2 > 0.98. The method was applied to real samples, revealing concentrations ranging from 13.58 to 55.46 μg L-1, all way below the legal limit in Brazil (Maximum Contaminant Levels (MCL) = 100 μg L-1). This cost-effective and straightforward method is suitable for integration into water treatment plant laboratories.

Trihalomethanes in water samples: Recent update on pretreatment and detection methods

Trihalomethanes (THMs) are classified as volatile organic compounds, considered to be a disinfection by-product during water disinfection process. THMs have been shown to be cytotoxic, genotoxic and mutagenic, with a risk of cancer when they contact with people directly. To protect public health and monitor water quality, it is important to monitor and measure THMs in drinking water. Therefore, it is crucial to develop fast, accurate, highly sensitivity and green analysis methods of THMs in various complicated matrices. Here, this review presents an overall summary of the current state of the pretreatment and detection methods for THMs in various sample matrices since 2005. In addition to the traditionally used pretreatment methods for THMs (such as headspace extraction, microwave-assisted extraction, liquid-liquid extraction), the new-developed methods, including solid-phase extraction, QuEChERS and different microextraction methods, have been summarized. The detection methods include gas chromatography-based methods, sensors and several other approaches. Additionally, benefits and limitations of different techniques were also discussed and compared. This study is anticipated to offer fruitful insights into the further advancement and widespread applications of pretreatment and detection technologies for THMs as well as for related substances.

Multi-exposure human health risks assessment of trihalomethanes in drinking water of Egypt

The present study aims to assess the probable lifetime cancer and non-cancer risks of exposure to the trihalomethanes in Egypt's drinking water through ingestion, dermal contact, and inhalation. A total of 1667 drinking water samples were collected from twenty-three Egyptian governorates over a three-years period. The concentrations of total trihalomethanes ranged between 29.07 and 86.01 μg/L and were always below the maximum contamination level recommended by the Egyptian standards (100 μg/L). Chloroform was the most prominent trihalomethanes species, while bromoform was rarely detected. The cancer risk study revealed that, among the investigated paths, inhalation poses the greatest risk. And bromodichloromethane had the highest impact to cancer (69%), followed by chlorodibromomethane (28%). Geographically, the highest cancer risk value was found in Matruh governorate (42.2 × 10^-6) and the lowest was in Minya governorate (1.0 × 10^-6). The cancer risk for the studied governorates, except Minya governorate, was higher than the level recommended by the USEPA (1.0 × 10^-6). Hazard index (HI) study revealed that the ingestion pathway caused higher HI values than the dermal pathway and that chloroform had the highest contribution to HI value. However, the values of HI were below unity in all studied governorates demonstrating that there would be negligible non-cancer risk.

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.

Green Approaches to Sample Preparation Based on Extraction Techniques

Preparing a sample for analysis is a crucial step of many analytical procedures. The goal of sample preparation is to provide a representative, homogenous sample that is free of interferences and compatible with the intended analytical method. Green approaches to sample preparation require that the consumption of hazardous organic solvents and energy be minimized or even eliminated in the analytical process. While no sample preparation is clearly the most environmentally friendly approach, complete elimination of this step is not always practical. In such cases, the extraction techniques which use low amounts of solvents or no solvents are considered ideal alternatives. This paper presents an overview of green extraction procedures and sample preparation methodologies, briefly introduces their theoretical principles, and describes the recent developments in food, pharmaceutical, environmental and bioanalytical chemistry applications.

Sample Enrichment for Bioanalytical Assessment of Disinfected Drinking Water: Concentrating the Polar, the Volatiles, and the Unknowns

Enrichment methods used in sample preparation for the bioanalytical assessment of disinfected drinking water result in the loss of volatile and hydrophilic disinfection byproducts (DBPs) and hence likely tend to underestimate biological effects. We developed and evaluated methods that are compatible with bioassays, for extracting nonvolatile and volatile DBPs from chlorinated and chloraminated drinking water to minimize the loss of analytes. For nonvolatile DBPs, solid-phase extraction (SPE) with TELOS ENV as solid phase performed superior compared to ten other sorbents. SPE yielded >70% recovery of nonpurgeable adsorbable organic halogens (AOX). For volatile DBPs, cryogenic vacuum distillation performed unsatisfactorily. Purge and cold-trap with crushed ice serving as condensation nuclei achieved recoveries of 50-100% for trihalomethanes and haloacetonitriles and approximately 60-90% for purged AOX from tap water. We compared the purgeable versus the nonpurgeable fraction by combining purge-and-trap extraction with SPE. The purgeable DBP fraction enriched with the purge-and-trap method exerted a lower oxidative stress response in mammalian cells than the nonpurgeable DBPs enriched with SPE after purging, while contributions of both fractions to bacterial cytotoxicity was more variable. 37 quantified DBPs explained almost the entire AOX in the purge-and-trap extracts, but <16% in the SPE extracts demonstrating that the nonpurgeable fraction is dominated by unknown DBPs.

Durable porous polyaniline supported ionic liquid coating for the highly effective solid phase microextraction of trace fatty alcohols in drinks

A polyaniline (PANI)-ionic liquid (IL) based solid phase microextraction (SPME) coating is presented.

Hollow-fiber solvent bar microextraction with gas chromatography and electron capture detection determination of disinfection byproducts in water samples

A liquid-phase microextraction method that uses a hollow-fiber solvent bar microextraction technique was developed by combining gas chromatography with electron capture detection for the analysis of four trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, and bromoform) in drinking water. In the microextraction process, 1-octanol was used as the solvent. The technique operates in a two-phase mode with a 5 min extraction time, a 700 rpm stirring speed, a 30°C extraction temperature, and NaCl concentration of 20%. After microextraction, one edge of the membrane was cut, and 1 μL of solvent was collected from the membrane using a 10 μL syringe. The solvent sample was directly injected into the gas chromatograph. The analytical characteristics of the developed method were as follows: detection limits, 0.017-0.037 ng mL^-1 ; linear working range, 10-900 ng mL^-1 ; recovery, 74 ± 9-91 ± 2; relative standard deviation, 5.7-10.3; and enrichment factor, 330-455. A simple, fast, economic, selective, and efficient method with big possibilities for automation was developed with a potential use to apply with other matrices and analytes.

Ionic liquids in microextraction techniques

The tremendous potential of room temperature ionic liquids as an alternative to environmentally harmful ordinary organic solvents is well recognized. Due to their unique properties, such as low volatility, tunable viscosity and miscibility, and electrolytic conductivity, ionic liquids have attracted extensive attention and gained popularity in many areas of analytical chemistry including modern sample preparation techniques. In this review the advantages and limitations of application of ionic liquids as solvents/sorbents for microextraction are critically discussed. Topics covered include solid-phase microextraction, single drop microextraction, dispersive liquid-liquid microextraction and hollow-fiber liquid-phase microextraction. The compatibility of the ionic liquid-based microextraction with different analytical techniques such as gas chromatography, high-performance liquid chromatography, electrothermal or flame atomic absorption spectrometry and some others is also discussed. Finally, the main practical applications on this topic are summarized.

Sensitive determination of terazosin in pharmaceutical formulations and biological samples by ionic-liquid microextraction prior to spectrofluorimetry

An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF₆] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L⁻¹ and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future.

Determination of chlorinated solvents in industrial water and wastewater by DAI-GC-ECD

A very simple and quick analytical method, based on direct aqueous injection, for determination of halogenated solvents in refinery water and wastewater, is described. There is a need to determine halogenated solvents in refinery water streams, because they may originate from several processes. There is also a need to develop methods enabling VOX to be determined in samples containing oil fractions. The method described enables simultaneous determination of 26 compounds with low detection limits (sub-μg L(-1)) and excellent precision, especially for highly halogenated solvents. The matrix effects of four types of sample were evaluated--the method seemed to be relatively insensitive to variations in matrix composition. Deuterated 1,2-dichloroethane was used as internal standard and surrogate compound in quantitative analysis; application of isotopically labelled compounds is rarely reported when non-mass spectrometric detectors are used for analysis. Analysis of real samples showed that the most frequently detected compounds were dichloromethane and 1,2-dichloroethane.

Analysis of trihalomethanes in water and air from indoor swimming pools using HS-SPME/GC/ECD

Headspace solid phase microextraction (HS-SPME) with further quantification by gas chromatography and electron capture detector (GC/ECD) was used to analyze trihalomethanes (THMs) in water and air from indoor swimming pools (ISPs). High correlation coefficients were obtained for the calibration lines in water with detection limits of 0.2 μg/L for trichloromethane (TCM) and bromodichloromethane (BDCM), 0.1 μg/L for dibromochloromethane (DBCM) and 0.5 μg/L for tribromomethane (TBM). Coefficients of variation values were 5-10% for repeatability and 15-25% for reproducibility. In air analysis, high correlation coefficients were also obtained for the calibration lines with detection limits of 2.5 μg/m(3) for TCM and BDCM and 1.25 μg/m(3) for DBCM and TBM. Repeatability and reproducibility coefficients of variation were the same as in water analysis. Analytical results from a survey in four Portuguese ISPs showed that the mean concentration of total trihalomethanes (TTHMs) in water ranged from 22±2 to 577±58 μg/L. In the lack of European specific regulation for THMs in water from ISPs and taking into consideration that ingestion is a form of exposure, TTHMs' values were compared with European drinking water maximum contamination level (100 μg/L, Directive 98/83/CE). From the reported TTHMs mean concentration values in ISPs' water, 40% exceeded that value. TTHMs values determined in the air (T = 30°C) ranged from 98±10 to 1225±123 μg/m(3) and from 51±5 μg/m(3)to 519±52 μg/m(3)at 5 and 150 cm above the water surface, respectively. As expected, swimmers are more exposed to high concentrations of THMs than lifeguards. As there is no European specific regulation for THMs in ISPs' air, the highest TCM values were compared with maximum values reported in the literature for ISPs (1630 μg/m(3)) and with the inhalation exposure limit (10,000 μg/m(3)) established for TCM by European occupational legislation (Directive 2000/39/CE).

Single drop microextraction--development, applications and future trends

Single drop microextraction (SDME) has emerged over the last 10-15 years as one of the simplest and most easily implemented forms of micro-scale sample cleanup and preconcentration. In the most common arrangement, an ordinary chromatography syringe is used to suspend microliter quantities of extracting solvent either directly immersed in the sample, or in the headspace above the sample. The same syringe is then used to introduce the solvent and extracted analytes into the chromatography system for identification and/or quantitation. This review article summarizes the historical development and various modes of the technique, some theoretical and practical aspects, recent trends and selected applications.

Ionic liquid-based dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of organophosphorus pesticides in water sample

Using 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) ionic liquid as extraction solvent, organophosphorus pesticides (OPPs) (parathion, phoxim, phorate and chlorpyifos) in water were determined by dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C(8)MIM][PF(6)] dispersed entirely into sample solution with the help of disperser solvent (methanol). Parameters including extraction solvent and its volume, disperser solvent and its volume, extraction time, centrifugal time, salt addition, extraction temperature and sample pH were investigated and optimized. Under the optimized conditions, up to 200-fold enrichment factor of analytes and acceptable extraction recovery (>70%) were obtained. The calibration curves were linear in the concentration range of 10.5-1045.0 microg L(-1) for parathion, 10.2-1020.0 microg L(-1) for phoxim, 54.5-1089.0 microg L(-1) for phorate and 27.2-1089.0 microg L(-1) for chlorpyifos, respectively. The limits of detection calculated at a signal-to-noise ratio of 3 were in the range of 0.1-5.0 microg L(-1). The relative standard deviations for seven replicate experiments at 200 microg L(-1) concentration level were less than 4.7%. The proposed method was applied to the analysis of four different sources water samples (tap, well, rain and Yellow River water) and the relative recoveries of spiked water samples are 99.9-115.4%, 101.8-113.7% and 87.3-117.6% at three different concentration levels of 75, 200 and 1000 microg L(-1), respectively.

Ionic liquids as superior solvents for headspace gas chromatography of residual solvents with very low vapor pressure, relevant for pharmaceutical final dosage forms

1-n-Butyl-3-methylimidazolium dimethyl phosphate (BMIM DMP) was identified as the most suitable ionic liquid as solvent for the headspace gas chromatographic analysis of solvents with very low vapor pressure such as dimethylsulfoxide, N-methylpyrrolidone, sulfolane, tetralin, and ethylene glycol in a realistic matrix of commonly used excipients (carboxymethylcellulose, magnesium stearate, guar flour, and corn starch) in pharmaceutical products. Limits of quantification and limits of detection were in the low microgram per gram range. The detection of traces of sulfolane in a real sample of tablets containing the drug cefpodoxim proxetil demonstrated the applicability of the method.