Solid phase extraction of gold(III) on silica gel modified with benzoylthiourea prior to its determination by flame atomic absorption spectrometry

A new method has been developed for the determination of gold based on separation and preconcentration using silica gel modified with benzoylthiourea. The optimum experimental parameters for preconcentration of gold, such as acid concentration, sample flow rate, eluent and matrix ions, have been investigated. Gold could be quantitatively retained in the 0.25-2.0 mol L(-1) HCl and HNO(3) concentrations, and then eluted completely with 0.5 mol L(-1) thiourea in 1.0 mol L(-1) HCl. The sorption capacity of gold(III) is 0.92 +/- 0.04 mmol g(-1) with a high enrichment factor of 267. The relative standard deviation of the method, RSD%, was found as 1.2% for 0.1 microg mL(-1). The detection limit for gold was 1.4 microg L(-1). The validation of the proposed method was checked by the analysis of certified reference soil materials. The presented procedure was applied to the determination of gold in some environmental samples.     

Solid phase extractive preconcentration of silver from aqueous samples

N,N-dibutyl-N1-benzoylthiourea (DBBT) impregnated onto a polymeric matrix, Amberlite XAD-16 was prepared. The separation and enrichment of Ag(I) from solution was investigated. Effective extraction conditions were optimized in column methods prior to determination by atomic absorption spectrometry. The optimum pH range for quantitative adsorption is 2-5. Quantitative recovery of Ag was achieved by stripping with 1 mol L(-1) thiourea in 1 mol L(-1) HCl. The sorption capacity of resin is 0.115 mmol Ag+ g(-1) resin. The relative standard deviation and detection limit was 3.1% for 1 microg Ag+ mL(-1) solution and 0.11 microg L(-1), respectively. The method was used for the determination of silver in geological water samples.     

The sensitive and selective determination of aluminium by spectrofluorimetric detection after complexation with N-o-vanillidine-2-amino-p-cresol

A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of aluminium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC), has been synthesized and its fluorescence activity with aluminium investigated. Based on this chelation reaction, a spectrofluorimetric method has been developed for the determination of aluminium in samples buffered at pH 4.0 using acetic acid-sodium acetate. The chelation reaction between Al(iii) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 20 min at room temperature to complex completely. The excitation and emission wavelengths were 423.0 and 553.0 nm, respectively, at which the OVAC-Al complex gave the maximum fluorescence intensity at pH 4.0 in a 50% ethanol-50% water medium. The interference from fluoride ions was minimized by the addition of Be(2+). Other ions were found not to interfere at the concentrations likely to be found in natural waters. Under these conditions, the calibration plot was linear up to 1000 microg L(-1) (r = 0.999). The limit of detection (3sigma) for the determination of Al(iii) was 0.19 microg L(-1) and the precision for multiple determinations of 3 ng mL(-1) Al(iii) prepared in ultra-pure water was found to be 0.29% (n = 16). The Schiff base ligand could be used to determine ultra-trace aluminium from natural waters. Analysis of environmental certified reference materials showed good agreement with the certified values. The procedure was found to be equally applicable to both fresh water and saline solutions (including sea water) using either normal external calibration or the standard additions method.     

Determination and evaluation of hexavalent chromium in power plant coal combustion by-products and cost-effective environmental remediation solutions using acid mine drainage

The chromium species leaching from a coal combustion fly ash landfill has been characterized as well as a novel approach to treat leachates rich in hexavalent chromium, Cr(VI), by using another natural waste by-product, acid mine drainage (AMD), has been investigated during this study. It is observed that as much as 8% (approximately 10 microg g(-1) in fly ash) of total chromium is converted to the Cr(VI) species during oxidative combustion of coal and remains in the resulting ash as a stable species, however, it is significantly mobile in water based leaching. Approximately 1.23 +/- 0.01 microg g(-1) of Cr(VI) was found in the landfill leachate from permanent deposits of aged fly ash. This study also confirmed the use of AMD, which often is in close proximity to coal combustion by-product landfills, is an extremely effective and economical remediation option for the elimination of hexavalent chromium in fly ash generated leachate. Speciated isotope dilution mass spectrometry (SIDMS), as described in EPA Method 6800, was used to analytically evaluate and validate the field application of the ferrous iron and chromate chemistry in the remediation of Cr(VI) runoff.     

Detection of Lead in Vegetables with New Chromogenic Reagent by Spectrophotometry

A new simple, rapid selective and highly sensitive chromogenic reagent dibromo-p-methyl-carboxyazo (DBMCA) was synthesized and studied in detail for the spectrophotometric detection of lead. In 0.25 M phosphoric acid medium, which greatly increases the selectivity, Lead reacts with DBMCA to form a 1:2 blue complex having a sensitivity absorption peak at 646 nm. Under optimal conditions, Beer's Law is obeyed over the range from 0.09 to 0.8 microg mL(-1) Pb (II) and the apparent molar absorptivity is 1.03 x 10(5) mL(-1) cm(-1). The detection limit and the variation coefficient were found to be 2.12 microg mL(-1) and 1.0% respectively. It is found that, except for Ca (II) and Ba (II) all foreign ions studied do not interfere with detection. The interference caused by Ca (II) and Ba (II) can be easily eliminated by prior extraction with potassiumiodide-methylisobutylketone. The proposed method has been applied successfully for to the detection of Lead in vegetable leaves with good results.     

Diffusive sampling of methyl isocyanate using 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ) as derivatizing agent

A diffusive sampling method for the determination of methyl isocyanate (MIC) in air is introduced. MIC is collected using a glass fiber filter impregnated with 4-nitro-7-piperazinobenzo-2-oxa-1,3-diazole (NBDPZ). The urea derivative formed is desorbed from the filter with acetonitrile and analyzed by means of high-performance liquid chromatography (HPLC) using fluorescence detection (FLD) with lambdaex = 471 nm and lambdaex = 540 nm. Additionally, a method was developed using tandem mass spectrometric (MS-MS) detection, which was performed as selected reaction monitoring (SRM) on the transition [MIC-NBDPZ + H]+ (m/z 307) to [NBDPZ + H]+ (m/z 250). The diffusive sampler was tested with MIC concentrations between 1 and 35 microg m(-3). The sampling periods varied from 15 min to 8 h, and the relative humidity (RH) was set from 20% up to 80%. The sampling rate for all 15 min experiments was determined to be 15.0 mL min(-1) (using HPLC-FLD) with a relative standard deviation of 9.9% for 56 experiments. At 80% RH, only 15 min sampling gave acceptable results. Further experiments revealed that humidity did not affect the MIC derivative but the reagent on the filter prior to and during sampling. The sampling rate for all experiments (including long term sampling) performed at 20% RH was found to be 15.0 mL min(-1) with a relative standard deviation of 6.3% (N = 42). The limit of quantification was 3 microg m(-3) (LC-MS-MS: 1.3 microg m(-3)) for 15 min sampling periods and 0.2 microg m(-3) (LC-MS-MS: 0.15 microg m(-3)) for 8 h sampling runs applying fluorescence detection.     

Method for the determination of sub-ppm concentrations of perfluoroalkylsulfonate anions in water

The determination of sub-ppm concentrations of aqueous perfluoroalkylsulfonate (PFSt) anions, including perfluorooctylsulfonate (PFOS), has been accomplished with a relatively simple mass spectrometric procedure that does not require extraction of the analytes into an organic solvent or a chromatographic separation prior to injection into the negative-ion electrospray ionization mass spectrometer. Sample pretreatment was minimized and consisted of dilution of the aqueous samples of groundwater, surface water, tap water, and distilled water with acetonitrile, addition of dodecylsulfate (DDS) as an internal standard, and, in some cases, addition of known amounts of perfluorobutylsulfonate (PFBS) or PFOS for standard-addition experiments. The linear-response range for PFOS is 25.0 microg L(-1) to 2.5 mg L(-1). The lower limit of this range is three orders of magnitude lower than an equally straightforward chromatographic method. The relative errors for standard aqueous solutions containing only 25.0 microg L(-1) and 2.5 mg L(-1) PFOS are +/- 14% and +/- 7%, respectively, with 133 microg L(-1) DDS as the internal standard. The detection limit and quantification limit for PFOS in these standards are 5.0 microg L(-1) and 25.0 microg L(-1), respectively. Six different PFS anions, containing three to eight carbon atoms, were identified and quantified in an aqueous film-forming foam (AFFF) formulation using the method of standard additions. Two alkylsulfate anions and two perfluoroalkylcarboxylate anions were also identified in the AFFF formulation.     

Analysis of indoor gaseous formic and acetic acid, using radial diffusive samplers

A diffusive sampling method for the determination of gaseous acetic and formic acids, using a radial symmetry diffusive sampler, has been optimised for a 7-day exposure time in this study. Sampling rate determinations were performed on data obtained from a dynamic exposure chamber, simulating the indoor conditions of an empty, closed, room, at room temperature and minimal wind speed. Analysis has been performed by means of ion chromatography. The sampling rates for formic acid concentrations of 128 microg m(-3) and 1248 microg m(-3) were determined to be 91.2 +/- 3.9 ml min(-1) and 111.6 +/- 2.8 ml min(-1), respectively. The acetic acid sampling rate was independent of the concentration in the range 160 microg m(-3)-1564 microg m(-3), and amounted to 97.3 +/- 3.1 ml min(-1). Experimentally determined sampling rates showed deviations of 3% for acetic acid, and 3-21% for formic acid, in relation to theoretically derived values. The blank values were as low as 1.69 +/- 0.07 microg for formic acid and 1.21 +/- 0.14 microg for acetic acid, and detection limits lower than 0.5 microg m(-3) could be achieved, which is an improvement of 98-99% compared to previously validated diffusive sampling methods. This study describes the first step of an extended validation program in which the applicability of these types of samplers for the measurement of organic acids will be validated and optimised for the environmental conditions typical for museum showcases.     

Spectrophotometric determination of ferbam (iron(III) dimethyldithiocarbamate) in commercial sample and wheat grains using 4,7-diphenyl-1,10-phenanthroline after extraction into mesityl oxide

A procedure has been developed for the determination of iron(III) dimethyldithiocarbamate by converting it into iron(II)-bathophenanthroline complex, which is then extracted into mesityl oxide in the presence of potassium perchlorate. The absorbance is then measured at 534 nm against a reagent blank. Beer's law is obeyed over the concentration range 0.5-20 microg ml(-1) in the final solution. The method is sensitive, highly selective and can be used for the determination of ferbam in a commercial sample, and in mixtures with various dithiocarbamates (ziram, zineb, maneb, etc.) and in wheat grains.     

恒电流库仑滴定法测定铬渣中的铬（Ⅵ）

铬渣样品以（１＋１０）磷酸溶液加热消解１．５ｈ，可得到完全澄清的消解液。采用恒电流库仓滴定法测定消解液中的Ｃｒ（Ⅵ），测得值（１．６４％）与标样参考值（１．７％）接近，准确度高，相对标准偏差为０．９８％。适于铬渣中Ｃｒ（Ⅵ）的日常监测。     

Chromium redox speciation in natural waters

Dissolved hexavalent chromium concentrations were determined in river, estuarine and coastal waters of the Humber catchment in north-east England. Samples were collected, filtered, extracted on site and after storage for up to eight days. Hexavalent chromium concentrations did not change by more than 0.05 microg l(-1) (not significant, p = 0.05) over this period. Total chromium concentrations in the catchment were less than 1.0 microg l(-1). This is low in relation to the proposed Environmental Quality Standard. Hexavalent chromium accounted for between 27% and 100% of the total dissolved concentration, with an average of approximately 50%. The proportion of Cr(III) and Cr(VI) in the rivers and estuary were of the same range as previously measured in 1993. The addition of Cr(III) and Cr(VI) to fresh and saline water samples illustrates the complexity of the factors controlling chromium speciation in natural waters. The presence of oxidisable organic matter and the stabilising role of complexing organic ligands are proposed as the main controlling influences of redox speciation in filtered samples.     

Determination of antimony in human blood with inductively coupled plasma-mass spectrometry

A method is presented for the determination of antimony in whole human blood samples with an ICP-MS instrument using a quadrupole mass analyzer. A nitric acid/hydrogen peroxide open digestion procedure was employed for the blood sample treatment and preparation for analysis. The precision and accuracy of the method were evaluated by analyzing several Seronorm trace elements whole blood reference materials. The precision of the method at various antimony levels was better than 4% RSD and the recovery was greater than 92% at all levels. The detection limit, calculated as three times the standard deviation of the blank (3sigma, n= 12), was 0.03 microg L(-1). The method was successfully applied for the determination of antimony in blood samples from school children in rural areas of Kwazulu/Natal, South Africa and adults from Dearborn, Michigan. Blood antimony levels ranged from <0.03 to 3.82 microg L(-1) in children and 1.40 to 4.35 microg L(-1) for adults.     

Quantification of protein adducts of hexahydrophthalic anhydride and methylhexahydrophthalic anhydride in human plasma

Hexahydrophthalic anhydride (HHPA) and methylhexahydrophthalic anhydride (MHHPA) are two highly allergenic compounds used in the chemical industry. A method was developed for quantification of protein adducts of HHPA and MHHPA in human plasma. The plasma was dialysed and the anhydrides were hydrolysed from the proteins at mild acidic conditions. The released hexahydrophthalic acid (HHP acid) and methylhexahydrophthalic acid (MHHP acid) were purified by reversed solid phase extraction followed by derivatisation with pentafluorobenzyl bromide. The derivatives were analysed using GC-MS in negative ion chemical ionisation mode with ammonia as moderating gas. As internal standards, deuterium labelled HHP and MHHP acids were used. The detection limits were 0.06 pmol mL(-1) plasma for HHP acid and 0.03 pmol mL(-1) plasma for MHHP acid. The between-day precisions for HHP acid were 18% at 0.3 pmol mL(-1) and 8% at 4 pmol mL(-1). For MHHP acid, the precisions were 13% at 0.3 pmol mL(-1) and 9% at 4 pmol mL(-1). There were strong correlations (r=0.94 for HHPA and 0.99 for MHHPA) between total plasma protein adduct concentrations and serum albumin adduct levels. Workers exposed to time-weighted average air levels of HHPA between < 1 and 340 microg m(-3) and between 2 and 160 microg m(-3) for MHHPA had plasma adduct levels between the detection limits of the methods and 8.40 and 19.0 pmol mL(-1), respectively.     

铬污染土壤中六价铬的测定

研究了土壤中Ｃｒ＾６＋的提取测定方法。结果表明，用０．４ｍｏｌ／Ｌ ＫＣｌ为提取剂，离心分离提取液，可简单，快速，准确地测定土壤中Ｃｒ＾６＋，所建立的方法适用于北方偏碱性土壤。     

Formaldehyde determination in seawater. Preliminary application to coastal samples at Terra Nova Bay (Antarctica)

A sensitive spectrofluorimetric-FIA (flow injection analysis) method for formaldehyde (HCHO) determination was improved with the aim of analysing seawater samples.The fluorescence emission versus HCHO concentration shows a linear pattern from sub microg L(-1) to about 1000 microg L(-1). The reproducibility at 15 ppb level is about 2%. Interferences from other aldehydes were checked; only glyoxal shows a significative interference, but only when its concentration is about 6000 times higher than that of formaldehyde. Superficial (microlayer, just sub-pack or sea-ice free sea surface) and deep (along the water column, sub-pack or in sea-ice free areas) seawater samples were collected near the coast at Terra Nova Bay (Ross Sea, Antarctica) during the 1998/1999 and 2001/2002 Italian Antarctic Expedition. We report here the preliminary results of the spectrofluorimetric-FIA determination of the HCHO content. The mean seawater superficial formaldehyde concentration was 15 microg L(-1); the concentration along the water column ranged between 4.5 to over 40 microg L(-1)(20 microg L(-1) mean concentration), usually with a maximum value for the 30 m depth, corresponding to a fluorescence maximum. The sampling was repeated 7 times in the austral summer in order to evaluate seasonal changes in the formaldehyde concentration/seawater depth profiles. The results show changes in the formaldehyde concentration at different depths.     

Sensitive spectrophotometric methods for the assessment of nitrite in water sample

Two spectrophotometric methods have been developed for the determination of nitrite using dapsone (DAP) with alpha-naphthol and 4-amino-5-hydroxynapthalene-2,7-disulphonic acid monosodium salt (AHNDMS) as chromogenic reagents with maximum absorbance wavelength at 540 and 520 nm respectively. For the method that utilizes dapsone with alpha-naphthol (DAP-alpha-naphthol), the beer's law range is obeyed between 0.05-0.8 microg ml(-1) with molar absorptivity of 5.749 x 104 l mol(-1) cm(-1). The second method that uses dapsone with AHNDMS (DAP-AHNDMS), the beer's law is valid over the range 0.2-1.4 mug ml(-1) and molar absorptivity 2.44 x 104 l mol(-1) cm(-1). The common interfering ions in the analytical procedures have been studied. This proposed methods are reliable, reproducible and have been successfully applied to determine nitrite in various water sources of environmental interest.     

Determination of copper in biological samples by flame atomic absorption spectrometry after precipitation with Me-BTAP

A simple and sensitive method was developed for determination of trace copper by direct precipitation preconcentration and detection with Flame Atomic Absorption Spectrometry (FAAS). The reagent 2-[2'-(6-methyl-benzothiazolylazo)]-4-aminophenol (Me-BTAP) was used as precipitating agent. The experimental conditions for the quantitative precipitation of copper, such as pH, amount of reagents, temperature and the effect of diverse ions on the precipitation have been investigated. It was found that copper is quantitatively extracted (> or =95%) and the method provides a sensitivity enhancement of 40-fold for a 10 ml sample volume with a detection limit of 0.5 microg l(-1). The proposed method was successfully applied for the determination of trace copper in water, urine and biological samples.     

Using environmental analytical data to estimate levels of community consumption of illicit drugs and abused pharmaceuticals

A solid phase extraction (SPE) method has been developed and applied in conjunction with a previously reported liquid chromatography tandem mass spectrometry (LC-MS-MS) procedure for the determination of illicit drugs and abused pharmaceuticals in treated wastewater and surface water samples at the ng L(-1) level. A full method validation was also performed and determined levels of analytical sensitivity were found to lie in the 1-10 ng L(-1) range using river water as a test sample matrix and a sample size of 500 mL. The developed procedure was successfully applied for the determination of the chosen analytes in wastewater treatment plants in Dublin, Ireland and rapidly expanding commuter towns in the surrounding counties. Cocaine was detected in 70% of the collected samples in the range of 25-489 ng L(-1), its primary metabolite, benzoylecognine (BZE) was also detected in the range of 22-290 ng L(-1). Other substances detected included morphine, Tempazepam and the primary metabolite of methadone.     

Development of a diffusive sampling method for determination of methyl isocyanate in air

A diffusive sampling method for determination of methyl isocyanate in air has been developed. A glass fibre filter impregnated with 1-(2-methoxyphenyl)piperazine in a commercially available diffusive sampling device was used to collect methyl isocyanate and the derivative formed was analysed with LC-MS/MS. The sampling rate was determined to be 15.6 ml min(-1), with a relative standard deviation of 7.3%. The sampler was validated for sampling periods from 15 min to 8 h, for relative humidities from 20% to 80% and for concentrations from I to 46 microg m(-3). A field validation was also made and the diffusive sampling results showed no difference compared to a pumped reference method. The impregnated filters have to be stored apart from the diffusive sampler housing and loaded into the sampler prior to each sampling.     

Determination of total Cr in wastewaters of Cr electroplating factories in the I.organize industry region (Kayseri, Turkey) by ICP-AES

The wastewater pollution in industrial areas is one of the most important environmental problems. Heavy metal pollution, especially chromium pollution in the wastewater sources from electroplating, dyeing, and tannery, has affected the life on earth. This pollution can affect on all ecosystems and human health directly or by food chain. Therefore, the determination of total chromium in this study is of great importance. In this study, accurate, rapid, sensitive, selective, simple, and low-cost technique for the direct determination of total Cr in wastewater samples collected from the some Cr electroplating factories in March 2008 by inductively coupled plasma-atomic emission spectrometry has been developed. The analysis of a given sample is completed in about 15 min by this technique applied. As the result of the chromium analysis, the limit of quantification for the total Cr were founded to be over the limit value (0.05 mg L^???1; WHO, EPA, TSE 266, and inland water quality classification) as 1,898.78 ± 0.34 mg/L at station 1 and 3,189.02 ± 0.56 mg/L at station 2. The found concentration of total Cr has been determined to be IV class quality water according to the inland water classification. In order to validate the applied method, recovery studies were performed.