Quantitative determination of sulfonated aliphatic and aromatic surfactants in sewage sludge by ion-pair/supercritical fluid extraction and derivatization gas chromatography/mass spectrometry.

Secondary alkanesulfonate (SAS) and linear alkylbenzene-sulfonate (LAS) surfactants were quantitatively (> 90%) extracted from sewage sludges as their tetrabutylammonium ion pairs using 400 atm of supercritical CO2 for 5 min of static extraction followed by 10 min of dynamic extraction at 80 degrees C. Ion pairs of SAS and LAS quantitatively formed butyl esters in the injection port of the gas chromatograph and were determined by gas chromatography/mass spectrometry without class fractionation of the sewage sludge extracts. Concentrations of SAS and LAS in sludges from five different sewage treatment plants ranged from 0.27 to 0.80 g/kg of dry sewage sluge and from 3.83 to 7.51 g/kg, respectively. Good reproducibility was achieved with RSDs of typically 5% for replicate extractions and analyses. Homologue and isomer distributions of SAS in sewage sludge indicated an enrichment of the more hydrophobic components in sewage sludge during sewage treatment.     

Miniaturized and automated sample pretreatment for determination of PCBs in environmental aqueous samples using an on-line microporous membrane liquid-liquid extraction-gas chromatography system

A new, fast, and automated sample pretreatment technique for determination of lipophilic organic compounds in aqueous samples has been developed and applied to the determination of polychlorinated biphenyls (PCBs) in environmental river water. It is based on miniaturized microporous membrane liquid-liquid extraction coupled on-line to gas chromatography (GC) with electron capture detection. The heart of the system that simultaneously connects the sample pretreatment step to the final GC analysis has been named the extracting syringe (ESy). The ESy carries a miniaturized membrane extraction card attached to an electrically and mechanically designed installment and is mounted directly over a GC injector for fully automated injection of the extract. A method was developed to extract 10 PCB congeners from 1-mL water samples (after addition of 40% acetonitrile) with an extraction time of 10 min. The optimized methodology showed good linearity (in the dynamic concentration range of 5 ng L(-)(1)-1 microg L(-)(1)), enrichment factors of 33-40 times, repeatable extractions (RSD 2-5%, n = 4), and low detection limits (2-3 ng L(-)(1)). Acetonitrile had to be added to the samples in order to overcome the influence of PCB adsorption on the repeatability of extraction and enrichment and to minimize the overall memory effect (OME). OME and carryover depended not only on the concentration of the organic solvent added to the sample and that used in the washing procedure but also on whether the extracting card was changed or not. When an optimized washing procedure was applied, the OME was approximately 0.2% at high concentrations (i.e., 1 microg L(-)(1)). When each extraction took place in a new extraction card, no OME was detected. Additionally, no significant adsorption onto glass surfaces or a matrix effect on extraction was noticed. The main features of this methodology are good extraction repeatability, low detection limits at short extraction time, and the unsurpassed characteristic of no detectable OME in the entire system when each sample is processed in a new card. The total consumption of organic (nonchlorinated) solvents is less than 5 mL per sample.     

Determination of benzotriazole corrosion inhibitors from aqueous environmental samples by liquid chromatography-electrospray ionization-tandem mass spectrometry

The first method for the determination of commonly used corrosion inhibitors in environmental water samples by liquid chromatography-electrospray ionization-tandem mass spectrometry is presented. Benzotriazole (BTri) and the two isomers of tolyltriazole (5- and 4-TTri) are separated in an isocratic run. By gradient elution, BTri, 4-TTri, 5-TTri, and xylyltriazole can be determined simultaneously with three benzothiazoles, but here TTri isomers coelute. The instrumental detection limit of 2 pg allows the determination of the three most important benzotriazoles from municipal wastewater and most surface waters by direct injection into the HPLC system without previous enrichment. When solid-phase extraction is employed with mean recovery rates of 95-113%, the limit of quantification for benzotriazoles range from 10 ng/L in groundwater to 25 ng/L in untreated wastewater. BTri and TTri were determined in municipal wastewater in microgram per liter concentrations. Elimination in wastewater treatment appears to be poor, and BTri and TTri can be followed through a water cycle from treated municipal wastewater through surface water to bank filtrate used for drinking water production. The TTri isomers show markedly different biodegradation behavior with 4-TTri being more stable.     

Method for analysis of polar volatile trace components in aqueous samples by gas chromatography

A new method has been developed for direct analysis of volatile polar trace compounds in aqueous samples by gas chromatography. Water samples are injected onto a short packed precolumn containing anhydrous lithium chloride. A capillary column is coupled in series with the prefractionation column for final separation of the analytes. The enrichment principle of the salt precolumn is reverse to the principles employed in conventional methods such as SPE or SPME in which a sorbent or adsorbent is utilized to trap or concentrate the analytes. Such methods are not efficient for highly polar compounds. In the LiCl precolumn concept, the water matrix is strongly retained on the hygroscopic salt, whereas polar as well as nonpolar volatile organic compounds show very low retention and are eluted ahead of the water. After transfer of the analytes to the capillary column, the retained bulk water is removed by backflushing the precolumn at elevated temperature. For direct injections of 120 microL of aqueous samples, the combined time for injection and preseparation is only 3.5 min. With this procedure, direct repetitive automated analyses of highly volatile polar compounds such as methanol or tetrahydrofuran can be performed, and a limit of quantification in the low parts-per-billion region utilizing a flame ionization detector is demonstrated.     

Enantiomeric separation and quantitative determination of atenolol in tablets by chiral high-performance liquid chromatography

The separation and quantitative determination of atenolol isomers by chiral high-performance liquid chromatography (HPLC) are described. Atenolol isomers were separated using a Chiralcel OD® column (250 × 4.6 mm,10 μm); the mobile phase was hexane-ethanol-diethylamine (75:25:0.1 v/v/v); ultraviolet detection was at 276 nm; and flow rate was 0.7 ml/min. The coefficient of variation and average recovery of (R)-isomer were 0.60% and 100.37%, respectively, for sample A and 0.69% and 100.63%, respectively, for sample B. The coefficient of variation and average recovery of (S)-isomer were 0.59% and 100.33%, respectively, for sample A and 0.63% and 99.78%, respectively, for sample B.     

Quantitative determination of absolute organohalogen concentrations in environmental samples by X-ray absorption spectroscopy

An in situ procedure for quantifying total organic and inorganic Cl concentrations in environmental samples based on X-ray absorption near-edge structure (XANES) spectroscopy has been developed. Cl 1s XANES spectra reflect contributions from all Cl species present in a sample, providing a definitive measure of total Cl concentration in chemically heterogeneous samples. Spectral features near the Cl K-absorption edge provide detailed information about the bonding state of Cl, whereas the absolute fluorescence intensity of the spectra is directly proportional to total Cl concentration, allowing for simultaneous determination of Cl speciation and concentration in plant, soil, and natural water samples. Absolute Cl concentrations are obtained from Cl 1s XANES spectra using a series of Cl standards in a matrix of uniform bulk density. With the high sensitivity of synchrotron-based X-ray absorption spectroscopy, Cl concentration can be reliably measured down to the 5-10 ppm range in solid and liquid samples. Referencing the characteristic near-edge features of Cl in various model compounds, we can distinguish between inorganic chloride (Cl(inorg)) and organochlorine (Cl(org)), as well as between aliphatic Cl(org) and aromatic Cl(org), with uncertainties in the range of approximately 6%. In addition, total organic and inorganic Br concentrations in sediment samples are quantified using a combination of Br 1s XANES and X-ray fluorescence (XRF) spectroscopy. Br concentration is detected down to approximately 1 ppm by XRF, and Br 1s XANES spectra allow quantification of the Br(inorg) and Br(org) fractions. These procedures provide nondestructive, element-specific techniques for quantification of Cl and Br concentrations that preclude extensive sample preparation.     

Stability of technetium and decontamination from ruthenium and molybdenum in determination of 99Tc in environmental solid samples by ICPMS

A rapid and efficient method for the determination of (99)Tc in environmental solid samples was developed using chromatographic separation combined with inductively coupled plasma mass spectrometry (ICPMS) measurement. The volatility of technetium during sample ashing and solution evaporation was investigated to establish a reliable sample pretreatment procedure. A novel approach was developed to improve the removal of molybdenum and ruthenium in chromatographic separation using 30% H(2)O(2) pretreatment of the loading solution and extraction chromatographic separation using two serial small TEVA columns. The decontamination factors of more than 4 × 10(4) and 1 × 10(5) are achieved for molybdenum and ruthenium, respectively. Chemical yields of technetium in entire procedure range from 60% to 95% depending on the type and amount of samples, and the detection limit of 0.15 mBq/g for (99)Tc was obtained. The method has been successfully applied for the determination of (99)Tc in environmental solid samples.     

Determination of nitrite in drinking water and environmental samples by ion exclusion chromatography with electrochemical detection

An extremely sensitive determination of nitrite in drinking water (tap water and underground water) and environmental samples (rain, lake water, and soil) was achieved by ion exclusion chromatography (IEC) with electrochemical (EC) detection. Potential interferences in the determination of nitrite by the standard spectrophotometric method or by the ion exchange chromatographic method with either conductivity detection or UV detection were eliminated. The detection limit was 0.1 ppb without preconcentration. No nitrite was observed from tap water or underground drinking water. The recoveries of nitrite added to tap water at 0.02, 0.1, and 1 ppm levels were between 96 and 104.5%. The average coefficient of variation was 4.7%. The recovery results were in good agreement with those obtained by the standard spectrophotometric method. Nitrite concentrations between 0.068 and 0.19 ppm were observed in rain within a week period. A greater variation, between 0.015 and 0.26 ppm, was observed in lake water. Amounts of 19.1 ppm and 0.50 ppm nitrite were observed from fertilized and unfertilized soil, respectively.     

Coupled-column liquid chromatography applied to the trace-level determination of triazine herbicides and some of their metabolites in water samples

In the present work, a study is reported of the potential of coupled-column liquid chromatography (LC) applied to the determination of triazine residues in environmental water samples. For this purpose, two different techniques have been compared: on-line trace enrichment followed by LC (SPE-LC) and coupled-column liquid chromatography (LC-LC). First, a completely automated liquid chromatographic method based on on-line trace enrichment in a prepacked precolumn and using diode array detection has been developed for the simultaneous trace-level determination of six triazine herbicides (simazine, cyanazine, atrazine, terbumeton, terbuthylazine, and terbutryn) and the main atrazine metabolites (desisopropylatrazine, desethylatrazine, and hydroxyatrazine). After preconcentration parameters were optimized by testing two different sorbents (C18 and PRP-1) in three cartridges with different dimensions, a sample volume of 100 mL was selected in order to achieve maximal solute preconcentration. Detection limits lower than 0.1 microgram.L-1 were obtained even for the most polar analyte (desisopropylatrazine), which presented recoveries of around 30%. The method was validated by means of recovery experiments in groundwater and surface water samples spiked with the analytes at different levels (0.2-2 micrograms.L-1). Afterward, the procedure was successfully applied in a program for monitoring of triazine residues in surface water carried out in a wet area of Castellón, Spain. Different triazine herbicides such as simazine, terbumeton, terbuthylazine, and terbutryn were identified and quantified. The identity of these compounds was confirmed by their absorption UV spectra and by GC/MS analysis. Finally, two rapid, sensitive, and selective procedures, previously developed in our laboratory for the trace-level determination of triazine compounds, both based on LC-LC, were compared with the former procedure. The SPE-LC approach showed a considerable improvement in the global sensitivity at the expense of a decrease in selectivity as well as in sample throughput.     

On-line preconcentration and determination of mercury in biological and environmental samples by cold vapor-atomic absorption spectrometry

An on-line procedure for the determination of traces of total mercury in environmental and biological samples is described. The present methodology combines cold vapor generation associated to atomic absorption spectrometry (CV-AAS) with preconcentration of the analyte on a minicolumn packed with activated carbon. The retained analyte was quantitatively eluted from the minicolumn with nitric acid. After that, volatile specie of mercury was generated by merging the acidified sample and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the atomizer device. Optimizations of both, preconcentration and mercury volatile specie generation variables were carried out using two level full factorial design (2(3)) with 3 replicates of the central point. Considering a sample consumption of 25mL, an enrichment factor of 13-fold was obtained. The detection limit (3sigma) was 10ngL(-1) and the precision (relative standard deviation) was 3.1% (n=10) at the 5microgL(-1) level. The calibration curve using the preconcentration system for mercury was linear with a correlation coefficient of 0.9995 at levels near the detection limit up to at least 1000microgL(-1). Satisfactory results were obtained for the analysis of mercury in tap water and hair samples.     

Preconcentration and determination of trace metal ions from aqueous samples by newly developed gallic acid modified Amberlite XAD-16 chelating resin

Gallic acid was immobilized on Amberlite XAD-16 by coupling it through -N=N group. The resulting chelating resin Amberlite XAD-16 gallic acid, characterized by thermogravimetric analysis (TGA), infrared (IR) spectra and BET analysis, was used to preconcentrate Cr(III), Mn(II),Fe(III),Co(II), Ni(II) and Cu(II)ions. The resin was employed for the preconcentration of the metal ions present in river water and industrial area aqueous samples. Several parameters like effect of pH, effect of time, effect of sample volume and flow rate of sample were investigated. The sorption capacities for the resin were 216 micromol g(-1), 180 micromol g(-1), 403 micromol g(-1), 281 micromol g(-1), 250 micromol g(-1) and 344 micromol g(-1) for Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) respectively. The preconcentration factors for Cr(III), Mn(II), Fe(III), Ni(II), Co(II) and Cu(II) were found out to be 300, 200, 400, 285.7, 300 and 400 respectively. The effect of various interfering ions was also studied. Results were validated by using standard addition method for river water sample.     

Solid-phase extraction procedure of polar benzene- and naphthalenesulfonates in industrial effluents followed by unequivocal determination with ion-pair chromatography/electrospray-mass spectrometry

Highly water soluble benzene- and naphthalenesulfonates are widely used in the chemical, pharmaceutical, tannery, paper, and textile industries. In this work, Isolute ENV+ polystyrene divinylbenzene sorbent was used for the enrichment of 14 benzene- and naphthalenesulfonates from industrial wastewaters. The elution step was performed by adding 1 mL of water containing ion-pair reagent (5 mM of triethylamine (TEA) and 5 mM of acetic acid at pH 6.5) and 9 mL of methanol at 1 mL/min. The most relevant contribution was the use of ion-pair liquid chromatography followed by an orthogonal electrospray interface coupled to mass spectrometry in the negative ionization mode with postcolumn addition at 0.2 mL/min of methanol in combination with a volatile substance (triethylamine) as an ion-pair reagent. [M-H](-) ion was the base peak using low fragmentor voltages of 80 V with the electrospray interface. Significant fragmentation of the quasimolecular [M-H](-) ion occurs at high fragmentor voltage, producing [M-SO(2)H](-), [M-SO(3)H](-), and [SO(3)](?)(-) as diagnostic ions. Collision-induced dissociation of the parent ions for the benzene- and naphthalenesulfonates studied gave the [SO(3)](?)(-) fragment ion common to sulfonated compounds. At high fragmentor voltages of 150 V, [M-SO(3)H](-) ion is more abundant and therefore has a larger peak than the [M-H](-) peaks for 1,5-naphthalenedisulfonate, 2,6-naphthalenedisulfonate, 1-hydroxy-3,6-naphthalenedisulfonate, 2-hydroxy-3,6-naphthalenedisulfonate, and 2-amino-1,5-naphthalenedisulfonate. Recoveries were higher than 70%, with relative standard deviations between 1.3 and 10.7% with the exception of two naphthalenesulfonate compounds that had recoveries between 26 and 41%. Limits of detection (signal-to-noise ratio, 3) ranging from 0.6 pg to 0.13 ng (0.03-6.48 μg/L) were achieved when 150 mL of groundwater was processed. The aromatic sulfonates 3-nitrobenzenesulfonate, 4-methylbenzenesulfonate, 4-chlorobenzenesulfonate, 1-hydroxy-4-naphthalenosulfonate, 1-amino-6-naphthalenosulfonate, 1-amino-7-naphthalenosulfonate, and 1-naphthalenesulfonate and the linear alkyl benzenesulfonates C(10)-LAS and C(11)-LAS were unequivocally identified and quantitatively determined in μg/L, in wastewater samples from wastewater treatment plants and textile and tannery industries. 2-Naphthalenesulfonate was found as a major pollutant at mg/L concentration levels.     

Speciation of organometallic compounds in environmental samples by gas chromatography after flow preconcentration on fullerenes and nanotubes

The development of a simple speciation method for the determination of lead (trimethyllead(I), dimethyllead(II), triethyllead(I), and diethyllead(II)), mercury (methylmercury(I), ethylmercury(I), mercury(II)), and tin (n-butyltin(III), di-n-butyltin(II), tri-n-butyltin(I), tin(IV)) compounds in environmental samples was described. The potential of C70 fullerenes and multiwalled carbon nanotubes (MWNTs) as sorbents was investigated for the first time; this study revealed that there are no significant differences between them in terms of sensitivity, selectivity, precision, and reusability. Comparative studies showed that MWNTs and C60 and C70 fullerenes were superior to graphitized carbon black and RP-C18 for the extraction of the 11 compounds studied. The accuracy of the MWNT method was evaluated from recovery values with two standard reference coastal sediments, and good concordance in the results were obtained. Detection limits of 0.5-2 pg/mL were obtained when using a sorbent column containing 160 mg of MWNTs (sample breakthrough, 50 mL of water). The method was successfully applied to the determination of lead, mercury, and tin compounds in water and coastal sediment samples with satisfactory results.