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ABSTRACT: A large volume direct aqueous injection method was developed for the analysis of iodinated haloacetic acids in drinking water by using reversed-phase liquid chromatography/electrospray ionization/tandem mass spectrometry in the negative ion mode. Both the external and internal standard calibration methods were studied for the analysis of monoiodoacetic acid, chloroiodoacetic acid, bromoiodoacetic acid, and diiodoacetic acid in drinking water. The use of a divert valve technique for the mobile phase solvent delay, along with isotopically labeled analogs used as internal standards, effectively reduced and compensated for the ionization suppression typically caused by coexisting common inorganic anions. Under the optimized method conditions, the mean absolute and relative recoveries resulting from the replicate fortified deionized water and chlorinated drinking water analyses were 83-107% with a relative standard deviation of 0.7-11.7% and 84-111% with a relative standard deviation of 0.8-12.1%, respectively. The method detection limits resulting from the external and internal standard calibrations, based on seven fortified deionized water replicates, were 0.7-2.3 ng/L and 0.5-1.9 ng/L, respectively.
Journal of chromatography. A 05/2012; 1245:75-82. · 4.19 Impact Factor
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ABSTRACT: A rapid, sensitive, and cost-effective analytical method was developed for the analysis of selected semi-volatile organic
compounds in water. The method used an automated online solid-phase extraction technique coupled with programmed-temperature
vaporization large-volume injection gas chromatography/mass spectrometry. The water samples were extracted by using a fully
automated mobile rack system based on x-y-z robotic techniques using syringes and disposable 96-well extraction plates. The
method was validated for the analysis of 30 semivolatile analytes in drinking water, groundwater, and surface water. For a
sample volume of 10 mL, the linear calibrations ranged from 0.01 or 0.05 to 2.5 μg·L−1, and the method detection limits were less than 0.1 μg·L−1. For the reagent water samples fortified at 1.0 μg·L−1 and 2.0 μg·L−1, the obtained mean absolute recoveries were 70%–130% with relative standard deviations of less than 20% for most analytes.
For the drinking water, groundwater, and surface water samples fortified at 1.0 μg·L−1, the obtained mean absolute recoveries were 50%–130% with relative standard deviations of less than 20% for most analytes.
The new method demonstrated three advantages: 1) no manipulation except the fortification of surrogate standards prior to
extraction; 2) significant cost reduction associated with sample collection, shipping, storage, and preparation; and 3) reduced
exposure to hazardous solvents and other chemicals. As a result, this new automated method can be used as an effective approach
for screening and/or compliance monitoring of selected semi-volatile organic compounds in water.
Keywordsautomated solid-phase extraction–programmed-temperature vaporization–large-volume injection–gas chromatography/mass spectrometry–semi-volatile organic compounds–water analysis
Frontiers of Environmental Science & Engineering in China 05/2012; 5(3):417-425. · 0.75 Impact Factor
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ABSTRACT: A new method was developed for the analysis of nitrate and nitrite in a variety of water matrices by using reversed-phase liquid chromatography/electrospray ionization/mass spectrometry in the negative ion mode. For this direct analysis method, nitrate and nitrite anions were well separated under the optimized LC conditions, detected by monitoring m/z 62 and m/z 46 ions, and quantitated by using an isotope dilution technique that utilized the isotopically labeled analogs. The method sensitivity, accuracy, and precision were investigated, along with matrix effects resulting from common inorganic matrix anions. The isotope dilution technique, along with sample pretreatment using barium, silver, and hydrogen cartridges, effectively compensated for the ionization suppression caused by the major water matrix anions, including chloride, sulfate, phosphate, and carbonate. The method detection limits, based on seven reagent water replicates fortified at 0.01 mg N/L nitrate and 0.1 mg N/L nitrite, were 0.001 mg N/L for nitrate and 0.012-0.014 mg N/L for nitrite. The mean recoveries from the replicate fortified reagent water and lab water samples containing the major water matrix anions, were 92-103% for nitrate with an imprecision (relative standard deviation, RSD) of 0.4-2.1% and 92-110% for nitrite with an RSD of 1.1-4.4%. For the analysis of nitrate and nitrite in drinking water, surface water, and groundwater samples, the obtained results were generally consistent with those obtained from the reference methods. The mean recoveries from the replicate matrix spikes were 92-123% for nitrate with an RSD of 0.6-7.7% and 105-113% for nitrite with an RSD of 0.3-1.8%.
Journal of chromatography. A 01/2011; 1218(3):476-83. · 4.19 Impact Factor
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ABSTRACT: 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.
Journal of Chromatography 01/2008; 1176(1-2):223-30. · 4.53 Impact Factor
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ABSTRACT: A liquid chromatography/electrospray ionization/mass spectrometry method was reported for the compliance analysis of seven phenylurea compounds and two related herbicides (tebuthiuron and propanil) in drinking water. The volumes of the sample and final extract used in the method were 500 mL and 10 mL, respectively. The obtained method detection limits were less than 0.03 microg/L, and the mean recoveries were 74-128% with a relative standard deviation of 2.6-8.3% for all the studied compounds. The peak-to-peak signal-to-noise ratios ranged from 3.3 for cis-siduron to 34.2 for fluometuron. The accuracy and precision resulting from reagent and drinking water samples fortified at higher concentration levels were similar to these results. Several analytes were detected in the drinking water samples, including tebuthiuron at 0.5 microg/L, propanil at 0.7 microg/L, diuron at 0.1-2.1 microg/L, and linuron at 0.1-0.8 microg/L.
Journal of Chromatography 12/2006; 1134(1-2):170-6. · 4.53 Impact Factor
