[Determination of benomyl, carbendazim and thiabendazole in apple juice concentrate using solid-phase extraction coupled with ion exchange chromatography]

A method was developed for the determination of benomyl, carbendazim and thiabendazole in apple juice concentrate by solid-phase extraction coupled with ion exchange chromatography (IEC). The sample was diluted with water, and then benomyl was degradated completely to carbendazim at 80 degrees C, and purified by an SCX solid-phase extraction column. Liquid chromatographic analysis was performed on the instrument of Agilent 1200 series equipped with a diode-array detector and autosampler. The column was LC-SCX (25 cm x 4.6 mm, 5 microm). The mobile phase was 0.1 mol/L KH2PO4 (pH 2.5)-acetonitrile (70:30, v/v) with a flow rate of 1.0 mL/min. The presented method showed good linear relationship with good precision and accuracy at the range of 0.02 - 2.0 mg/L for carbendazim and thiabendazole. The detection limits were 0. 004 mg/kg for carbendazim and thiabendazole. The method was characterized with acceptable sensitivity to meet the requirements for monitoring these pesticides in apple juice concentrate.

Reflectometric cutinase assay for rapid screening of contaminants and residues of insecticidal organophosphates and carbamates

Because of the extensive use of insecticides in agriculture, there is an increasing demand for rapid analytical methods for residues in food and feed control. To meet this need, a completely new application of the reflectometric lipase test (Reflectoquant, Merck) was developed. By using the cutinase-induced reaction of the substrate 5-bromo-4-chloro-3-indoxyl caprylate on the test strips, residues of organophosphates and carbamates can be determined on the basis of enzyme inhibition in a fast and inexpensive way. With this technique, we investigated the inhibition effects of representative insecticides, i.e., chlorpyrifos oxon, paraoxon, and carbaryl. The bimolecular inhibitory rate constants (ki) were found to agree well with those obtained by a previously described spectrophotometric cutinase assay in the microtiter-plate format. Recoveries determined with the strip test from spiked samples compared well with those obtained by both the cutinase microtiter-plate assay and liquid chromatographylmass spectrometry.

Quality Control of Protease Inhibitors

Protease inhibitors (PIs) are potent competitive inhibitors of the human immunodeficiency virus (HIV) widely used in the treatment of the acquired immune deficiency syndrome (AIDS) and prescribed in combination with other antiretroviral drugs. So far ten PIs were approved by the United States Food and Drug Administration (FDA) for the treatment of HIV infection. In this mini review, quality control methods of each PI are discussed on the basis of analytical techniques published in the literature. Special attention is given to summarize the LC methods described for the analysis of the selected PIs in both drug substances and products with the available literature till date.

A comparative study of first-derivative spectrophotometry and column high-performance liquid chromatography applied to the determination of repaglinide in tablets and for dissolution testing

A fast and reliable method for the determination of repaglinide is highly desirable to support formulation screening and quality control. A first-derivative UV spectroscopic method was developed for the determination of repaglinide in tablet dosage form and for dissolution testing. First-derivative UV absorbance was measured at 253 nm. The developed method was validated for linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) in comparison to the U.S. Pharmacopeia (USP) column high-performance liquid chromatographic (HPLC) method. The first-derivative UV spectrophotometric method showed excellent linearity [correlation coefficient (r) = 0.9999] in the concentration range of 1-35 microg/mL and precision (relative standard deviation < 1.5%). The LOD and LOQ were 0.23 and 0.72 microg/mL, respectively, and good recoveries were achieved (98-101.8%). Statistical comparison of results of the first-derivative UV spectrophotometric and the USP HPLC methods using the t-test showed that there was no significant difference between the 2 methods. Additionally, the method was successfully used for the dissolution test of repaglinide and was found to be reliable, simple, fast, and inexpensive.

Analysis of polyamines as carbamoyl derivatives in urine and serum by liquid chromatography-tandem mass spectrometry

A quantitative analysis of polyamines in urine and serum by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described. The polyamines were carbamylated with isobutyl chloroformate, extracted with diethyl ether under pH 9.0, and analyzed by LC-MS/MS with single reaction monitoring mode. The limit of quantification was 1 ng/mL based on a signal-to-noise ratio>3, and the correlation coefficient (r2) for the calibration curves was >0.99 for both urine and serum samples. The present method was applied to urine and serum samples from 30 breast cancer patients and 30 normal female controls. There was no significant difference in the urinary polyamine levels between breast cancer patients and controls. However, 1,3-diaminopropane, putrescine, spermine and N-acetylspermidine levels in serum increased in breast cancer patients. These four serum polyamines may be a good index to study both production and metabolism of polyamines, and a useful tool in assessment of the polyamine status of breast cancer patients.

Same patient, new stone composition: amprenavir urinary stone

We report here the first case to add amprenavir to the growing list of antiretroviral drugs associated with urinary stones. The first reported case of a nelfinavir urinary stone was reported in 2002 in a 37-year-old HIV-infected woman. In September 2007, the same female patient was referred to our department with recent onset of right flank pain and recurrent urinary tract infections. Abdominal computed tomography revealed three obstructing stones in the distal right ureter, another stone in the right renal pelvis with hydronephrosis and a stone in the left kidney. After stone retrieval, analysis of the stone by liquid chromatography with mass spectrometry revealed a stone composition of 95% unmodified amprenavir and 5% ritonavir.

Multienzyme inhibition assay for residue analysis of insecticidal organophosphates and carbamates

A recently developed spectrophotometric assay for the detection of organophosphorus and carbamate insecticides by means of cutinase inhibition has been successfully extended to two esterases derived from Bacillus subtilis (BS2) and rabbit liver. These esterases were selected because of their high sensitivity to the examined insecticide classes and their pronounced inhibition profile. With inhibition constants (ki) of 2.0x10(7) and 2.6x10(6) L/(mol.min) for rabbit liver esterase and BS2, respectively, chlorpyrifos oxon proved to be the strongest inhibitor directly followed by paraoxon. As compared to choline esterases and the recently studied cutinase, both esterases are surprisingly strongly inhibited by organophosphorus thions, showing k i in the range of 5.3x10(2) to 2.3x10(4) L/(mol.min). All tested insecticidal carbamates were also inhibitors of BS2 and rabbit liver esterase, albeit in a rather uniform manner. Generally, both enzymes were found to be about 2 orders of magnitude more sensitive on the studied insecticides than cutinase even with an enhanced sensitivity against plant matrix effects. Plant extracts, obtained according to the QuEChERS method, were subjected to solid-phase extraction (SPE) using a mixed mode strong anion exchanger/primary secondary amine sorbent and C18endcapped cartridges for superior cleanup. With spiked samples of apple juice, best recoveries of 73% (+/-61%), 94% (+/-25%), and 134% (+/-17%) were obtained for chlorpyrifos, parathion-methyl, and paraoxon, respectively. Results of exemplarily performed liquid chromatography-mass spectrometry control measurements were well in accordance with measurements obtained by enzyme inhibition.

[Survey of pesticide residues in baby foods (1999.4-2005.6)]

A survey of pesticide residues in 316 baby foods on the Tokyo market from April 1999 to June 2005 was carried out. Fifteen kinds of pesticides, including organophosphorus, organochlorine, carbamate, pyrethroid and others, were detected between at levels Tr (below 0.01 ppm) and 0.55 ppm from 28 samples. The baby foods in which residual pesticides were detected were produced from flour, leaf vegetable and fruits. The pesticides were detected in baby foods produced with minimal processing, such as straining and squeezing. For the baby foods containing pesticides, the amounts of intake of the pesticides were calculated from the recommended servings, and compared with the ADI values. Residual pesticide levels in baby food were between 0.06 and 16.6% of the ADI. Therefore, these foods should be safe in normal usage.

Solid-phase microextraction-liquid chromatography-mass spectrometry applied to the analysis of insecticides in honey

An approach based on solid-phase microextraction-liquid chromatography-mass spectrometry (SPME-LC-MS) has been developed for determining 12 insecticides (bromophos ethyl, chlorpyrifos methyl, chlorpyrifos ethyl, diazinon, fenoxycarb, fonofos, phenthoate, phosalone, pirimiphos methyl, profenofos, pyrazophos, and temephos) in honey. The influence of several parameters on the efficiency of the SPME was systematically investigated. Under optimal conditions, the procedure provided excellent linearity (>0.990), detection and quantification limits (between 0.001 and 0.1 microg g(-1) and between 0.005 and 0.5 microg g(-1), respectively), and precision (<19% at the quantification limits and from 6 to 14% at ten times higher concentrations). However, recoveries were not so good, ranging from 19 to 92%. Honey samples were found that were contaminated with bromophos ethyl, diazinon, fonofos, pirimiphos ethyl, pyrazophos, and temephos at estimated concentrations from 6.2 +/- 1.2 to 19 +/- 3 ng g(-1).

Determination of N-methylcarbamate pesticides in environmental samples by an automated solid-phase extraction and liquid chromatographic method based on post-column photolysis and chemiluminescence detection

An automated solid-phase extraction-high performance liquid chromatography method has been developed to determine trace concentration of N-methylcarbamate pesticides in water and fruits. The method is based on the post-column conversion of the pesticides into methylamine by irradiation with UV light. The resultant methylamine was subsequently detected by chemiluminescence using tris(2,2'-bipyridyl)ruthenium(III), which was on-line generated by photo-oxidation of the ruthenium(II) complex with peroxydisulfate. Factors affecting the rate of the reactions were optimized so that their contribution to the total band-broadening was negligible. This detection system was used to determine bendiocarb, carbaryl, promecarb and propoxur, which were separated on an ODS C(18) column. The mobile phase consisted of water and acetonitrile using a gradient elution. A linear relationship between peak area and concentration was obtained for all pesticides (r(2)>0.999). Intra- and inter-day precision values of about 0.64-1.3% RSD (n=10) and 2.2-2.8% RSD (n=15), respectively, were obtained. N-Methylcarbamate pesticide residues at ultratrace levels could be determined in environmental samples when an automated solid-phase extraction device was coupled on-line with the HPLC system. Detection limits were within the range 3.9-36.7 ngl(-1) for water samples and 0.5-4.7 microgkg(-1) for fruits.

Development and evaluation of an immunoassay for the monitoring of the anti-HIV drug amprenavir

An assay for routine therapeutic drug monitoring of anti-HIV HAART drugs in clinical use is highly desirable, in order to rapidly measure the pharmacokinetic parameters on single patients. We have started a project to develop a panel of enzyme-linked immunosorbent assays (ELISA) for the whole set of HAART drugs, and the development, performance and evaluation of the assay for amprenavir is described here. A diazo conjugate of amprenavir has been used in order to raise polyclonal anti-amprenavir antibodies in rabbits. Antisera have been used to set up a quantitative and rapid competitive assay. Plasma samples are simply diluted in the assay buffer after thermal inactivation, before running the assay. The assay allows the detection of amprenavir in the quantification range 400-5000 ng/ml, in a diluted plasma sample. The assay has been compared with an HPLC reference technique, on 27 samples from treated patients. Within the quantification range, the ELISA data are well correlated with the HPLC results by a regression line close to the identity, and a Bland-Altman analysis shows the agreement between the two methods.

Amperometric biosensing of carbamate and organophosphate pesticides utilizing screen-printed tyrosinase-modified electrodes

A tyrosinase (Tyr) screen-printed biosensor based on the electroreduction of enzymatically generated quinoid products was electrochemically characterized and optimized for determination of carbamates and organophosphorus pesticides. A composite electrode prepared by screen-printing a cobalt (II) phthalocyanine (CoPc) modified cellulose-graphite composite on a polycarbonate support was employed as electrochemical transducer. The Tyr biosensor was prepared by immobilization of enzyme on the composite electrode surface by cross-linking with glutaraldehyde and bovine serum albumin. Parameters affecting the biosensor response such as response time, enzyme loading, concentration and pH of the buffer solution were optimized utilizing catechol as substrate. The maximum response for o-quinone enzymatically generated was obtained after 2 min of reaction. A good reproducibility and high operational stability were found for Tyr biosensor (60 units) at 50 mM phosphate buffer, pH 6.50. Under these conditions, the useful lifetime of biosensor was 10 days. After 15 days, the biosensor could be used with 20% of the initial value. Inhibition studies on the o-quinone steady-state current (at -0.20 V versus Ag/AgCl) were performed to investigate the inhibition kinetics of the pesticides in the enzymatic activity of mushroom tyrosinase. The results shown that the methyl parathion and carbofuran can lead to competitive inhibition process of the enzyme, while diazinon and carbaryl act as mixed inhibitors. Linear relationships were found for methyl parathion (6-100 ppb), diazinon (19-50 ppb), carbofuran (5-90 ppb) and carbaryl (10-50 ppb). Analysis of natural river water samples spiked with 30 ppb of each pesticide showed recoveries between 92.50% and 98.50% and relative standard deviations of 2%.

Development of a RP-HPLC method for screening potentially counterfeit anti-diabetic drugs

Pharmaceutical counterfeiting is becoming a serious problem in the world, especially in developing countries including China. Herein an isocratic reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for screening counterfeit medicines and adulterated dietary supplement products. The developed method could be employed to separate and determine simultaneously six anti-diabetic drugs (glipizide, gliclazide, glibenclamide, glimepiride, gliquidone, repaglinide) on an isocratic solvent system using an Alltima C18 column (5 microm, 150 mmx4.6 mm) with an isocratic mobile phase of methanol-phosphate buffer (pH 3.0; 0.01 mol/L) (70:30, v/v), at a flow rate of 1.0 mL/min and at a wavelength of 230 nm. The proposed method was successfully applied to the analysis of medicinal and dietary supplement samples purchased from the local market in China.

Cholinesterase-based dipstick assay for the detection of organophosphate and carbamate pesticides

A cholinesterase (ChE)-based dipstick-type assay for the class-specific detection of organophosphate (OP) and carbamate (CM) pesticides was developed. The principle of the assay is based on inhibition of the activity of a ChE by these two families of pesticides, which is dependent on the concentration of pesticides. The proposed assay system is composed of a test strip with an acetylcholinesterase (AChE)-coated membrane and an enzyme substrate solution. The assay protocol involves incubation of the enzyme-coated strip in the pesticide-containing sample solution followed by incubation of the sample-treated strip in a chromogenic enzyme substrate solution. The color intensity is estimated by the naked eye or a reflectometer. Of the membranes tested as the enzyme support, Hybond N+ was the most suitable. Among the compounds tested as the enzyme substrate, indophenyl acetate was the best. The detectable concentration range of the dipstick assay for the OP and CM pesticides was 10(-6)-10(2) and 10(-6)-10(0) microg mL(-1), respectively. The sensitivity of the dipstick assay to the oxidized form of parathion (paraoxon) was higher than to parathion. The strip showed a large matrix effect with pesticide-spiked lettuce samples, whereas it showed a small matrix effect with pesticide-spiked rice samples.

Facile and sensitive spectrophotometric determination of carbosulfan in formulations and environmental samples

Facile, selective and sensitive spectrophotometric method has been developed for the determination of carbosulfan in insecticidal formulations, fortified water, food grains, agriculture wastewater and soil samples with newly synthesized reagents. The method was based on acid and alkaline hydrolysis of the carbosulfan pesticide, and the resultant hydrolysis product of carbosulfan was coupled with 2,6-dibromo-4-methylaniline to give a yellow color product with lambda(max) of 464 nm or interaction with 2,6-dibromo-4-nitroaniline to produce yellow colored product with lambda(max) of 408 nm or coupling with 2,4,6-tribromoaniline to form red colored product has a lambda(max) of 471 nm. Under optimal conditions, Beer's law range for 2,6-dibromo-4-methylaniline (DBMA) was found to be 0.2-12.0 microg ml(-1), 0.6-16.0 microg ml(-1) for 2,6-dibromo-4-nitroaniline (DBNA) and 0.4-15.0 microg ml(-1) for 2,4,6-tribromoaniline (TBA). The molar absorptivity of the color systems were found to be 3.112 x 10(4) l mol(-1) cm(-1) for DBMA, 3.214 x 10(4) l mol(-1) cm(-1) for DBNA and 3.881 x 10(4) l mol(-1) cm(-1) for TBA. Sandell's of the color reactions are 0.013 microg cm(-2) (DBMA), 0.012 microg cm(-2) (DBNA) and 0.011 microg cm(-2) (TBA) respectively. The effect of the non-target species on the determination of carbosulfan was studied to enhance the selectivity of the proposed methods. The formation of colored derivatives with the coupling agents is instantaneous and stable for 28, 30, and 26 h. Performance of the proposed methods were compared statistically in terms Student's F and t-tests with the reported methods.

Determination of thiophanate methyl and carbendazim residues in vegetable samples using microwave-assisted extraction

Microwave-assisted extraction (MAE) was carried out for the determination of the fungicides thiophanate methyl [1.2-alpha-(3-methoxycarbonyl-2-thioureido)benzene] and carbendazim (methyl benzimidazol-2-ylcarbamate) in vegetable samples. Two vegetable samples, cabbage and tomatoes, were fortified with the two pesticides and subjected to MAE followed by cleanup to remove co-extractives prior to analysis by high-performance liquid chromatography (HPLC). Using the selected microwave exposure time and power setting, the recoveries of carbendazim ranged from 69 to 75%. But thiophanate methyl could not be recovered as the parent compound. It was converted and recovered as carbendazim. The conversion was quantitative as confirmed by high-performance liquid chromatography-mass spectrometry (HPLC-MS).

[Determination of carbamate pesticides in reservoir water by hollow fiber-based liquid phase microextraction coupled with high performance liquid chromatography]

An analytical method for the determination of carbamate pesticides (carbofuran, carbaryl, isoprocarb and diethofencarb) in reservoir water using hollow fiber-based liquid phase microextraction (HF-LPME) coupled with high performance liquid chromatography (HPLC) was developed. Some main experimental parameters that affect the extraction efficiency were optimized. Toluene was selected as both the extraction solvent and the impregnation solvent. The extraction was carried out at room temperature (20 degrees C ) in a 5 mL Teflon-lined septum cap vial filled with 4.5 mL of sample solution at a stirring rate of 720 r/min for 20 min. The extract was dried under nitrogen stream at room temperature. The dried residue was then dissolved in the mobile phase for HPLC analysis. The separation was carried out on a Baseline C18 column (4.6 mm x 250 mm, 5.0 microm) with methanol-water (60:40, v/v) as the mobile phase at a flow rate of 1.0 mL/min. The detection for carbofuran, carbaryl, isoprocarb and diethofencarb was selected at 200, 223, 200 and 208 nm, respectively. The average enrichment factors for the four analytes were greater than 45. The linear range for the quantification of the four analytes was 10 - 100 microg/L (r > 0.99). The limits of detection (LODs) were 5, 1, 5 and 3 microg/L (S/N = 3) for carbofuran, carbaryl, isoprocarb and diethofencarb, respectively. Good recoveries (82.0% - 102.2%) and good reproducibilities (2.0% - 6.2%, n = 6) were achieved.

Understanding the degradation pathway of a poorly water-soluble drug formulated in PEG-400

VX-497 is a poorly water-soluble compound. It is formulated in PEG-400 and encapsulated in softgel capsules. Although the drug product is stable at refrigerated conditions, many degradation peaks have been observed at accelerated storage conditions. An investigation utilizing high performance liquid chromatography-mass spectrometry (HPLC-MS) was conducted to understand the degradation mechanism of the active pharmaceutical ingredient (VX-497) in PEG-400 formulation. Results revealed that the degradation was mainly caused by the reaction between VX-497 with moisture (hydrolysis) and PEG-400 (PEGylation). The numerous degradation peaks observed in the samples stored at accelerated conditions were PEG adducts covalently attached to portions of the VX-497 molecule, which were confirmed by comparison with synthetic markers. Investigation also found that an impurity, which was present in the VX-497 drug substance, reacted with PEG-400 following the same reaction mechanism, and generated additional impurities in the VX-497 drug product. By changing the process for drug substance synthesis, pure batches of VX-497 were obtained. Furthermore, it was found that the reaction between VX-497 and PEG-400 was temperature and time dependent. When the drug product was manufactured at 45 degrees C and the processing time was controlled, the PEG degradants and by-products were reduced to non-detectable levels, resulting in greatly improved drug product quality. This paper presents an integrated effort among analytical, process, and formulation scientists on how to develop a better drug product by understanding the fundamental issues of the drug product, namely the degradation mechanism.

Analysis of Some Chlorophenoxy Acids and Carbamate Herbicides in Water and Soil as Amide Derivatives Using Gas Chromatography--Mass Spectrometry

A newly developed method for determining three phenoxy acids and one carbamate herbicide in water and soil samples using gas chromatography with mass spectrometric detection is developed. Phenoxy acids are derivatized through a condensation reaction with a suitable aromatic amine. 1,1-Carbonyldiimidazole is used as a condensation reagent. Derivatization conditions are optimized with respect to the amount of analyte, amine, solvent, and derivatization reagent. The optimum derivatization yield is accomplished in acetonitrile. 4-Methoxy aniline is used as a derivatizing agent. Obtained derivatives are stable indefinitely. Enhancement in sensitivity is achieved by using the single-ion monitoring mass spectrometric mode. The effectiveness of the developed method is tested by determining investigated compounds in water and soil samples. Analytes are concentrated from water samples using liquid-phase extraction and solid-phase extraction. Soil samples are extracted using methanol. Detection limits of 1.00, 50.00, 100.00, and 1.00 ng/mL are obtained for 2-(1-methylethoxy)phenyl methylcarbamate (Baygon), 2-(3-chlorophenoxy)-propionic acid (Cloprop), 2,4,5-trichlorophenoxyacetic acid, and 4-(2,4-dichlorophenoxy)butyric acid, respectively. LPE for spiked water samples yields recoveries in the range of 60.6-95.7%, with relative standard deviation (RSD) values of 1.07-7.85% using single component calibration curves. Recoveries of 44.8-275.5%, with RSD values ranging from 1.43% to 8.61% were obtained using a mixed component calibration curves. SPE from water samples and soil samples showed low recoveries. The reason is attributed to the weak sorption capabilities of soil and Al(2)O(3).

Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry Analysis of Carbosulfan, Carbofuran, 3-Hydroxycarbofuran, and Other Metabolites in Food

The potential of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS) to identify and confirm carbosulfan and seven of its main metabolites (carbofuran, 3-hydroxycarbofuran, 3-ketocarbofuran, 3-hydroxy-7-phenol carbofuran, 3-keto-7-phenolcarbofuran, 7-phenolcarbofuran, dibutylamine) at trace levels from food is explored for the first time. The analytical method developed consists of pressurized liquid extraction (PLE) and LC-QqTOF-MS in positive ion mode, which attains unequivocal identification and quantification of the studied compounds in food, at levels well below of those of concern (0.05 mg/kg for the sum of carbosulfan, carbofuran, and 3-hydroxycarbofuran). PLE recoveries ranged from 55 to 94% with limits of quantification from 10 (for carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine) to 70 microg/kg (3-keto-7-phenolcarbofuran). The method is precise, with relative standard deviations varying between 5 and 11% for the repeatability (within-day) and 8-13% for the reproducibility (interday). This method was used to monitor the presence and fate of the target compounds in orange, potato, and rice crops treated with a commercial product containing carbosulfan. Field degradation studies show that carbofuran, 3-hydroxycarbofuran, and dibutylamine are the main degradation products formed in the environmental disappearance of carbosulfan.

Determination of tsumacide residues in vegetable samples using a flow-injection chemiluminescence method

A sensitive, simple and rapid flow-injection chemiluminescence (FI-CL) method is described to determine tsumacide pesticide residue based on the CL reaction of the alkaline degradation product of tsumacide with acidic KMnO(4) when rhodamine 6G was present. Under the optimum conditions, the relative CL intensity is linear with the concentration of tsumacide in the range of 2.0 x 10(-3)-0.20 mg/L. The detection limit is 6.6 x 10(-4) mg/L (3sigma) and the relative standard deviation for 2.0 x 10(-2) mg/L tsumacide solution was 2.28% (intra-day) and 4.85% (inter-day). The proposed method has been applied to determine the residue of tsumacide in vegetable samples and the recovery test is very satisfactory.

Photo-induced chemiluminometric determination of Karbutilate in a continuous-flow Multicommutation assembly

The present paper deals with the chemiluminescent determination of the herbicide Karbutilate on the basis of its previous photodegradation by using a low-pressure Hg lamp as UV source in a continuous-flow multicommutation assembly (a solenoid valves set). The pesticide solution was segmented by a solenoid valve and sequentially alternated with segments of the 0.001 mol l(-1) of NaOH solution, the suitable media for the formation of photo-fragments; then it passes through the photo-reactor and was lead to the flow-cell after being divided in small segments which were sequentially alternated with the oxidizing system; 2 x 10(-5) mol l(-1) of potassium permanganate in 0.2% pyrophosphoric acid. The studied calibration range, from 0.1 microg l(-1) to 65 mg l(-1), resulted in a linear behaviour over the range 20 microg l(-1)-20 mg l(-1) and fitting the linear equation: I=(1180+/-30)C+(15+/-5) with the correlation coefficient 0.9998. The limit of detection was 10 microg l(-1) and the sample throughput 17 h(-1). After testing the influence of a large series of potential interfering species, the method was applied to water and human urine samples.

Ion chromatography/inductively coupled plasma mass spectrometry for simultaneous determination of glyphosate, glufosinate, fosamine and ethephon at nanogram levels in water

This paper describes the first approach that simultaneously quantifies four polar, water-soluble organophosphorus herbicides, i.e., glyphosate, glufosinate, fosamine and ethephon, at nanogram levels in environmental waters. The target herbicides were separated completely by ion chromatography (IC) on a polymer anion-exchange column, Dionex IonPac AS16 (4.0 mm x 250 mm), with 30 mM citric acid flowing at 0.70 mL min(-1) as the eluent. On-line inductively coupled plasma mass spectrometry (ICP-MS) using a quadrupole mass spectrometer was employed as a sensitive and selective detector of the effluents. Various parameters affecting the separation and detection were systematically examined and optimized. Detection limits of the herbicides achieved with the proposed IC/ICP-MS method were 1.1-1.4 microg L(-1) (as compound) based on a 500-microL sample injection. Matrix anions, metal ions, phosphate, polyphosphates, non-polar and other polar organophosphorus pesticides showed no interference. The developed method was validated using reservoir water, treated water and NEWater samples spiked at the level of 10-25 microg L(-1) with satisfactory recoveries (95-109%). It is applicable to the simultaneous determination of microg L(-1) concentrations of the herbicides in polluted water.

Biocides used in building materials and their leaching behavior to sewer systems

There is increasing concern about diffuse pollution of aquatic systems by biocides used in urban areas. We investigated sources and pathways of biocides significant for the pollution of storm water runoff. Main sources seem to be building envelopes, i.e. facades (paints, plasters) and roof sealing membranes. First results from a defined urban catchment drained by a separated sewer system without any agricultural activities reveal a substantial occurrence. Even after the first flush, concentrations of terbutryn, carbendazim, mecoprop as well as Irgarol 1051 and its metabolite exceeded the Swiss water quality standard of 0.1 microg/L. In laboratory experiments, leaching of mecoprop used as a root protection agent in bitumen sheets for roof waterproofing was determined. The concentrations differed in 16 different sheets two orders of magnitude, depending on the product composition. Using optimized products, it is expected to be the most efficient and sustainable way to reduce the environmental impact. To understand transport dynamics and environmental risk, further storm water events will be analyzed. Based on the ongoing project URBIC, first measures will be proposed to limit the release to surface and ground water.