Simultaneous analysis of carbamate pesticides in tap and raw water by LC/ESI/MS.

Ten carbamate pesticides including four suspected endocrine disruptors, methomyl, benomyl (carbendazim), aldicarb and carbaryl, were simultaneously analyzed by LC/ESI/MS. The influence of the matrix on the variation of the ion signal intensities of (M + H)+ and adduct ions was investigated. Although the intensities of three oxamyl ions changed depending on the matrix, the variation in the concentration calculation of oxamyl was reduced by using the sum total of the area value of two ions. The limits of the quantitation of ten pesticides without a concentration procedure were from 0.4 - 30 microg/l. The solid-phase recovery rates of ten pesticides spiked into tap water and raw water were in the range of 69-111%. Using this method, the concentrations of the pesticides in tap and raw water sampled at 14 monitoring points in Hyogo Prefecture were determined. Carbendazim in three raw water samples and carbofuran in one of these three samples were detected at low concentrations (less than 0.32 microg/l).     

Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation

Bromate is a well known by-product produced by the ozonisation of drinking water; the allowed concentration for human consumption has to be regulated to the low microg l(-1) range. A direct injection, ion chromatographic method was developed using a tetraborate eluent with serially connected conductivity and spectrophotometric detection. Bromate was detected after post-column reaction with fuchsin at 520 nm. Sample capacity was investigated by injecting large volumes (up to 6 ml) using a high total hardness and chloride tap water. Linear correlation of bromate response with volumes from 1 ml to 6 ml was demonstrated, the main limitation being the overlapping of the chloride peak with bromate. Up to 1.5 ml sample can be injected without any pre-treatment. With more than 1.5 ml injection volume, a sample pre-treatment with a cartridge in Ag and H form, followed by a 10 min degassing in an ultrasonic bath, was needed. This method was validated by analysing secondary reference materials and real samples from a drinking water treatment plant. The method was linear from the limit of quantification to 20 microg l(-1). Reproducibilities in tap water were 18% (5 microg l(-1), n=12) and 21% (1 microg l(-1), n=4) respectively for 1.5 and 6 ml injection volumes with conductivity detection, and 17% at 0.5 microg l(-1) (n=9) with spectrophotometric detection. Calculated detection limits were 0.5 microg l(-1) (6 ml) ahd 2 microg l(-1) (1.5 ml) for conductivity detection and 0.3 microg l(-1) (1.5 ml) for spectrophotometric detection.     

Solid-phase microextraction for the analysis of short-chain chlorinated paraffins in water samples

A novel solid-phase microextraction (SPME) method coupled to gas chromatography with electron capture detection (GC-ECD) was developed as an alternative to liquid-liquid and solid-phase extraction for the analysis of short-chain chlorinated paraffins (SCCPs) in water samples. The extraction efficiency of five different commercially available fibres was evaluated and the 100-microm polydimethylsiloxane coating was the most suitable for the absorption of the SCCPs. Optimisation of several SPME parameters, such as extraction time and temperature, ionic strength and desorption time, was performed. Quality parameters were established using Milli-Q, tap water and river water. Linearity ranged between 0.06 and 6 microg l(-1) for spiked Milli-Q water and between 0.6 and 6 microg l(-1) for natural waters. The precision of the SPME-GC-ECD method for the three aqueous matrices was similar and gave relative standard deviations (RSD) between 12 and 14%. The limit of detection (LOD) was 0.02 microg l(-1) for Milli-Q water and 0.3 microg l(-1) for both tap water and river water. The optimised SPME-GC-ECD method was successfully applied to the determination of SCCPs in river water samples.     

Optimization of nonequilibrium liquid-phase microextraction for the determination of nitrobenzenes in aqueous samples by gas chromatography-electron capture detection.

In the present work, a novel method for the determination of nitrobenzenes in water has been described. It is based on nonequilibrium liquid-phase microextraction and gas chromatography-electron capture detection (GC-ECD). Extraction conditions such as solvent selection, organic solvent dropsize, stirring rate, content of NaCl and extraction time were found to have significant influence on extraction efficiency. The optimized conditions were 1.5 microl toluene and 20 min extraction time at 400 rpm stirring rate without NaCl addition. The linear range was 0.1 - 50 microg l(-1) for most nitrobenzenes. The limits of detection (LODs) ranged from 0.02 microg l(-1) (for 2.6-DNT) to 0.4 microg l(-1) (for NB); and relative standard deviations (RSD) for most of the nitrobenzenes at the 10 microg l(-1) level, except for 2,6-DNT in 3 microg l(-1), were below 10%. Natural samples collected from Miyun Reservoir and tap water samples from a laboratory were successfully analyzed using the proposed method, but none of the analytes were detected. The relative recoveries of spiked water samples (at the 10 microg l(-1) level except for 2,6-DNT in 3 microg l(-1)) were from 82.6 to 118.7%.     

Ionic liquid-based liquid-phase microextraction, a new sample enrichment procedure for liquid chromatography

Room temperature ionic liquids (RTILs) were used as extraction solvent in liquid-phase microextraction (LPME) coupled with liquid chromatography. Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) as extraction solvent, some parameters related to LPME of 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP) were optimized. Although [C6MIM][PF6] can suspend a much larger volume of drop on the needle of the microsyringe than the conventional solvents such as 1-octanol and carbon tetrachloride, the method sensitivity was analyte dependent because of the different partition coefficients and the relatively large viscosity of [C6MIM][PF6]. The proposed procedure has a detection limit and enrichment factor of 0.3 microg l(-1) and 163 for 4-NP, and 0.7 microg l(-1) and 130 for 4-t-OP, respectively. Aqueous samples including tap water, river water, and effluent from sewage treatment plant were analyzed by the proposed method and the recoveries at 10 microg l(-1) spiked level were in the range of 90-113%.     

A simple supported liquid hollow fiber membrane microextraction for sample preparation of trihalomethanes in water samples

A simple and efficient liquid-phase microextraction (LPME) technique using a supported liquid hollow fiber membrane, in conjunction with gas chromatography-electron capture detector has been developed for extraction and determination of trihalomethanes (THMs) in water samples. THMs were extracted from water samples through an organic extracting solvent impregnated in the pores and filled inside the porous hollow fiber membrane. Our simple conditions were conducted at 35 degrees C with no stirring and no salt addition in order to minimize sample preparation steps. Parameters such as types of hollow fiber membranes, extracting solvents and extraction time were studied and optimized. The method exhibited enrichment factors ranged from 28- to 62-fold within 30 min extraction time. The linearity of the method ranged from 0.2 to 100 microg l(-1). The limits of detection were in the low microg l(-1) level, ranging between 0.01 and 0.2 microg l(-1). The recoveries of spiked THMs at 5 microg l(-1) in water were between 98 and 105% with relative standard deviations (RSDs) less than 4%. Furthermore, the method was applied for determination of THMs in drinking water and tap water samples was reported.     

Determination of some organophosphorus and azole group pesticides in water samples by dispersive liquid-liquid microextraction coupled with GC/MS

A dispersive liquid-liquid microextraction (DLLME) procedure coupled with GC/MS detection is described for preconcentration and determination of some organophosphorus and azole group pesticides from water samples. Experimental conditions affecting the DLLME procedure were optimized by means of an experimental design. A mixture of 60 microL chlorobenzene (extraction solvent) and 750 microL acetonitrile (disperser solvent), 3.5 min extraction time, and 7.5 mL aqueous sample volume were chosen for the best recovery by DLLME. The linear range was 1.6-32 microg/L. The LOD ranged from 48.8 to 68.7 ng/L. The RSD values for organophosphorus and azole group pesticides at spiking levels of 3, 6, and 9 microg/L in water samples were in the range of 1.1-12.8%. The applicability and accuracy of the developed method were determined by analysis of spiked water samples, and the recoveries of the analyzed pesticides from artesian, stream, and tap waters at spiking levels of 3, 6, and 9 microg/L were 89.3-105.6, 89.5-103.0, and 92.0-111.3%, respectively.     

Trace analysis of ten chlorinated benzenes in water by headspace solid-phase microextraction

Headspace solid-phase microextraction (SPME), as a simple, solvent-free method, has been applied to the analysis of 10 chlorinated benzenes (CBs) present at trace levels in water samples. An SPME fibre coated with 100-microm thick poly(dimethylsiloxane) was used for extraction. The analytical data exhibited a relative standard deviation (RSD) range of 1.19% (for pentachlorobenzene) to 8.19% (for hexachlorobenzene) for the 10 CBs; the RSD of most compounds was under 6%. The sensitivity of the method was enhanced with agitation and with addition of salt to the sample solutions. With mass spectrometric detection, the limit of detection was below 0.006 microg/l for all 10 CBs after a 30-min sampling time. The linearity range was 0.02-20 microg/l for the compounds studied. Water samples collected from a reservoir, and from the tap in a laboratory were analysed using the optimised conditions.     

Fiber optic multi-channel protein detector for use in preparative continuous annular chromatography

On-line coupling continuous-flow liquid membrane extraction (CFLME) with HPLC, a novel automatic system was developed for the determination of sulfonylurea herbicides in water. After an automatic trace-enrichment process by CFLME, which is the combination of continuous flow liquid-liquid extraction and support liquid membrane (SLM) extraction, the target analytes were concentrated in 50 microl of 0.2 M Na2CO3-NaHCO3 (pH 10.0) buffer. The concentrated sample solutions were injected directly onto a C18 analytical column with a valve, and detected at 240 nm with a diode array detector. Metsulfuron methyl (MSM), and DPX-A 7881 were baseline separated with a mobile phase consisting of methanol and 67 mM KH2PO4-Na2HPO4 (pH 5.91) buffer (45+55, v+v) at a flow-rate of 1.0 ml min(-1). With an enrichment time of 10 min and enrichment sample volume of 20 ml, the enrichment factors and detection limits are 100 and 0.05 microg l(-1) for MSM, and 96 and 0.1 microg l(-1) for DPX-A 7881, respectively. The linear range and precision (RSD) are 0.1-50 microg l(-1) and 7.0% for MSM, and 0.2-50 microg l(-1) and 9.2% for DPX-A 7881, respectively. This proposed method was applied to determine MSM and DPX-A 7881 in seawater, tap water, and bottled mineral water with spiked recoveries in the range of 83-95% for MSM and 88-100% for DPX-A 7881, respectively.     

Determination of haloacetic acids in aqueous environments by solid-phase extraction followed by ion-pair liquid chromatography-electrospray ionization mass spectrometric detection.

Haloacetic acids (HAAs) were determined in different water samples by a new, fast and simple analysis method based on enrichment of 50-ml water samples at pH 1.8 by solid-phase extraction (SPE) followed by liquid chromatography (LC) separation and electrospray ionization mass spectrometric detection in the negative ionization mode. Deprotonated (M-H)-haloacetates and decarboxylated (M-COOH)- ions were detected. Different polymeric SPE sorbents were tested, and LiChrolut EN was found to be the best material for the extraction. Complete LC separation of all compounds could only be achieved by ion-pair chromatography using triethylamine as volatile ion-pairing reagent. The detection limits were in the low microg/l range. High microg/l concentration levels for the chlorinated and brominated haloacetates were found in drinking water from a drinking water treatment plant in Barcelona, and the corresponding tap water. In swimming pool water samples from Catalonia mg/l levels and in surface river water from Portugal microg/l values were detected. These results confirm other recent reports on the ubiquitous occurrence of HAAs in aqueous environments.     

Determination of trace amounts of off-flavor compounds in drinking water by stir bar sorptive extraction and thermal desorption GC-MS.

A method for the determination of trace amounts of off-flavor compounds including 2-methylisoborneol, geosmin and 2,4,6-trichloroanisole in drinking water was developed using the stir bar sorptive extraction technique followed by thermal desorption-GC-MS analysis. The extraction conditions such as extraction mode, salt addition, extraction temperature, sample volume and extraction time were examined. Water samples (20, 40 and 60 ml) were extracted for 60-240 min at room temperature (25 degrees C) using stir bars with a length of 10 mm and coated with a 500 microm layer of polydimethylsiloxane. The extract was analyzed by thermal desorption-GC-MS in the selected ion monitoring mode. The method showed good linearity over the concentration range from 0.1 or 0.2 or 0.5 to 100 ng l(-1) for all the target analytes, and the correlation coefficients were greater than 0.9987. The detection limits ranged from 0.022 to 0.16 ng l(-1). The recoveries (89-109%) and precision (RSD: 0.80-3.7%) of the method were examined by analyzing raw water and tap water samples fortified at the 1 ng l(-1) level. The method was successfully applied to low-level samples (raw water and tap water).     

Multiresidue determination of pesticides in drinking and related waters by gas chromatography/mass spectrometry after solid-phase extraction: interlaboratory study

As part of a project funded by the European Commission (EC) for the development and evaluation of multiresidue methods for analysis of drinking and related waters, 15 European laboratories evaluated a method using styrene-divinylbenzene co-polymer solid-phase extraction followed by gas chromatography/mass spectrometry. The main aim of the study was to evaluate whether the method meets the requirements of EC Directive 98/83 in terms of accuracy, precision, and detection limit for 22 pesticides according to the following requirements: limit of detection, < or = 0.025 microg/L; accuracy, expressed as recovery between 75 and 125%; and precision, expressed as repeatability relative standard deviation of the method of < 12.5% and as reproducibility relative standard deviation of the method of < 25%. Analyses for unknown concentrations were performed with fortified commercial bottled and tap waters. All laboratories were able to achieve detection limits of 0.01 microg/L for all pesticides except dimethoate and desisopropylatrazine (0.02 microg/L). The criteria for repeatability were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and chlorpyrifos, dimethoate, and lindane in tap water. The criteria for reproducibility were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and pendimethalin, chlorpyrifos, dimethoate, terbutryn, and lindane in tap water. In terms of accuracy, the method meets the requirements for all pesticides in both matrixes, except for lindane in bottled water and lindane and chlorpyrifos in tap water.     

Determination of chlorobenzenes in water by drop-based liquid-phase microextraction and gas chromatography-electron capture detection

A drop-based liquid phase microextraction and gas chromatographic-electron capture detection (GC-ECD) method was described for the determination of chlorobenzenes including chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene and 1,2,3-trichlorobenzene in 5 ml of water. The method used 2 microl of n-hexane as extraction solvent, 5 min extraction time, a stirring rate of 600 rpm and sample ionic strength of 3 M maintained with sodium chloride at 25 degrees C (ambient temperature). The limits of detection (LODs) ranged from 0.004 microg l(-1) (for 1,3-dichlorobenzene) to 0.008 microg l(-1) (for monochlorobenzene). The dynamic linear range for all investigated chlorobenzenes was 1-50 microg l(-1). Recoveries of chlorobenzenes from fortified distilled water are over 90% for three different fortification levels (5, 15 and 45 microg l(-1)) and relative standard deviations of the recoveries are below 6%. Analysis of fortified (5 microg l(-1)) real water samples revealed that matrices had no adverse effect on extraction efficiency of proposed method. The recovery of fortified real water samples was from 90 to 94% with relative standard deviations below 6%.     

Online in situ analysis of selected semi-volatile organic compounds in water by automated microscale solid-phase extraction with large-volume injection/gas chromatography/mass spectrometry

A fully automated analytical method was developed for the online in situ analysis of selected semi-volatile organic compounds in water. The method used a large-volume injection/gas chromatography/mass spectrometry coupled with a fully automated microscale solid-phase extraction technique, which was based on x-y-z robotic techniques. Water samples were extracted by using a 96-well solid-phase extraction plate. For most analytes included in this study, the obtained linear calibrations ranged from 0.05 to 5.0 microg/L with correlation coefficients of 0.996-1.000, the method detection limits were less than 0.1 microg/L, and the relative recoveries were in the range of 70-120% with a relative standard deviation of less than 15% for fortified reagent water samples. The applications to chlorinated tap water, well water, and river water have been validated. The obtained results were similar to those resulting from fortified reagent water samples for all analytes except metribuzin, bromacil, aldrin, and methoxychlor. Matrix effects were observed for these analytes. In general, this fully automated analytical method was rugged, reliable, and easy to operate, and was capable of providing real-time data to water treatment and distribution systems as well as water reservation and protection systems. In addition, the method could reduce the analytical costs associated with sample collection, transportation, storage, and preparation.     

Analysis of aldehydes in water by solid-phase microextraction with on-fiber derivatization

The solid-phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of aldehydes in water. The poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber was used and O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) were first loaded onto the fiber. The aldehydes in water sample were agitated into headspace and extracted by SPME with on-fiber derivatization. Gas chromatography/mass spectrometry (GC/MS) was used for the analysis of oximes formed and the adsorption-time profiles were examined. The precision, recovery and method detection limits (MDLs) were evaluated with spiked bidistilled water, chlorinated tap water as well as well water. The relative standard deviations from different spiked water sample were all less than 10% and the recoveries were 100 +/- 15%. With 2 ml of water sample, MDLs were in the range of 0.12-0.34 microg/l. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of aldehydes in water.     

Solid-phase extraction versus solid-phase microextraction for the determination of chlorinated paraffins in water using gas chromatography-negative chemical ionisation mass spectrometry

Solid-phase extraction (SPE) and solid-phase microextraction (SPME) were evaluated for the analysis of short-chain chlorinated paraffins (SCCPs) in water samples using gas chromatography coupled to negative chemical ionisation mass spectrometry (GC-NCI-MS). For SPE optimisation, four commercially available SPE cartridges were tested and several SPE parameters, such as the elution solvent, elution volume and breakthrough volume were studied. The best results were obtained with Varian Bond Elut-C18. In order to achieve a high selectivity in the determination of SCCPs, GC-NCI-MS was used. Quality parameters of the optimised SPE and SPME procedures were determined, and the best results were obtained for the SPE/GC-NCI-MS method with LODs of 5 and 20 ng l(-1) for tap and river water, respectively. This method was successfully applied to the analysis of SCCPs in river water samples at concentrations below the microg l(-1) level.     

Ionic liquid for high temperature headspace liquid-phase microextraction of chlorinated anilines in environmental water samples

Based on the non-volatility of room temperature ionic liquids (IL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) IL was employed as an advantageous extraction solvent for high temperature headspace liquid-phase microextraction (LPME) of chloroanilines in environmental water samples. At high temperature of 90 degrees C, 4-chloroaniline, 2-chloroaniline, 3,4-dichloroaniline, and 2,4-dichloroaniline were extracted into a 10 microl drop of [C4MIM][PF6] suspended on the needle of a high-performance liquid chromatography (HPLC) microsyringe held at the headspace of the samples. Then, the IL was injected directly into the HPLC system for determination. Parameters related to LPME were optimized, and high selectivity and low detection limits of the four chlorinated anilines were obtained because the extraction was performed at high temperature in headspace mode and the very high affinity between IL and chlorinated anilines. The proposed procedure was applied for the analysis of the real samples including tap water, river water and wastewater samples from a petrochemical plant and a printworks, and only 3,4-dichloroaniline was detected in the printworks wastewater at 88.2 microg l(-1) level. The recoveries for the four chlorinated anilines in the four samples were all in the range of 81.9-99.6% at 25 microg l(-1) spiked level.     

Simplified method for determination of polycarbamate fungicide in water samples by liquid chromatography with tandem mass spectrometry following derivatization with dimethyl sulfate

A simple and sensitive analytical method for the determination of polycarbamate in water samples was developed. In this method, polycarbamate was cleaved under alkaline conditions and derivatized with dimethyl sulfate to methyl dimethyldithiocarbamate (DMDC-methyl) and dimethyl ethylenebisdithiocarbamate (EBDC-dimethyl). After the solid-phase extraction of the resulting methyl derivatives, they were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS), based on reversed-phase separation and MS/MS detection with positive atmospheric pressure chemical ionization. The absolute recoveries (mean+/-SD) all through the procedure from polycarbamate to DMDC-methyl and EBDC-dimethyl were 62.6+/-4.3 and 73.5+/-5.9%, respectively. The limits of detection and quantification of polycarbamate in the water samples were 0.061 and 0.20 microg/L in the form of DMDC-methyl, and 0.032 and 0.11 microg/L in the form of EBDC-dimethyl, respectively. The method was validated at levels of 0.25, 1.0, and 5.0 microg/L in the tap water and river water samples, and accuracy was achieved in the range of 94-109%. The proposed method can be applied to the determination of trace amounts of polycarbamate in environmental water samples.     

Improved coupled-column liquid chromatographic method for the determination of glyphosate and aminomethylphosphonic acid residues in environmental waters

An existing method for the determination of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in water has been improved. It is based on precolumn derivatization with the fluorescent reagent 9-fluorenylmethylcloroformate (FMOC) followed by large-volume injection in a coupled-column LC system using fluorescence detection (LC-LC-FD). The derivatization step was slightly modified by changing parameters such as volume and/or concentration of sample and reagents to decrease the limits of quantification (LOQ) of glyphosate and AMPA to 0.1 microg/l. Additionally, the use of Amberlite IRA-900 for preconcentration of glyphosate, prior to the derivatization step, was investigated; the LOQ of glyphosate was lowered to 0.02 microg/l. Drinking, surface and ground water spiked with glyphosate and AMPA at 0.1-10 microg/l concentrations were analysed by the improved LC-LC-FD method. Recoveries were 87-106% with relative standard deviations lower than 8%. Drinking and ground water spiked with glyphosate at 0.02 and 0.1 microg/l were analysed after preconcentration on the anion-exchange resin with satisfactory recoveries (94-105%) and precision (better than 8%).     

Analysis by liquid chromatography-electrospray ionization tandem mass spectrometry and acute toxicity evaluation for beta-blockers and lipid-regulating agents in wastewater samples

This paper describes a multiresidue method for the extraction and determination of two therapeutic groups of pharmaceuticals, lipid-regulating agents (clofibric acid, bezafibrate, gemfibrocil, fenofibrate) and beta-blockers (atenolol, sotalol, metoprolol, betaxolol) in waters by solid-phase extraction followed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Recoveries obtained from spiked HPLC water, as well as, from spiked real samples (sewage treatment plants influent and effluents, river and tap water) were all above 60%, with the exception of betaxolol with a 52% recovery. The quantitative MS analysis was performed using a multiple reaction monitoring. The LC-MS-MS method gave detection limits ranging from 0.017 to 1.25 microg/l in spiked effluent. Precision of the method, calculated as relative standard deviation, ranged from 3.7 to 18.5%. Individual and combined effects on Daphnia magna were evaluated for both therapeutic groups. Individual effects in culture medium showed these compounds as not harmful and not toxic, an exception is fenofibrate that was found to be harmful, but at high, in the environment unrealistic concentrations (EC50 of 50 mg/l). Combined effect in wastewater showed synergistic toxic effects at low concentration level (2 microg/l).