Determination of iron,cobalt, nickel,manganese, zinc,copper, cadmium and lead in human hair by inductively coupled plasma-atomic emission spectrometry

A method was standardized for the dissolution of hair samples and analysis was carried out by inductively coupled plasma atomic emission spectrometry (ICP-AES). Hair samples were brought into solution by using a mixture of nitric acid and hydrogen peroxide. Various parameters that influence the sample preparation, namely temperature, digestion time and ratio of acid mixture were studied and standardized. The optimized method has been employed to digest standard reference materials and hair samples of residents of India, collected from different age groups and sex, and analyzed for Fe, Co, Ni, Mn, Zn, Cu, Cd and Pb. The values agree for most of the metals with the data reported for human hair samples of residents of India. The NIES CRM Human Hair No. 5 and IAEA Reference Hair HH-1 certified reference materials were used in order to verify the accuracy of the method and the results were in excellent agreement with the certified values.     

New procedure of silica gel surface modification preparation of gaseous standard mixtures for calibration purposes

The new type of silica gel surface modification with using the trimethylamine as a reagent is described. The samples of chemically modified silica gel have been used for generation of gaseous standard mixtures (methyl chloride as a measurand) using the technique of thermal decomposition of the surface compound. The main aim of the research was to check the suitability of the new type of silica gel surface modification for obtaining methyl chloride as a measurand of gaseous standard mixture. The gaseous standard mixture obtained with using this technique was used for calibration of a thermal desorber-gas chromatography-flame ionization detector (TD-GC-FID) system. The homogeneity of coverage of silica gel surface with the immobilized compound has been evaluated. The full uncertainty budget of determination of liberated amount of methyl chloride has been calculated. The average amount of methyl chloride liberated from the unit sample of chemically modified silica gel is 3.59 +/- 0.13 mg g(-1). The influence of the modification way on the amount of liberated analyte has also been determined.     

Extractive separation of trace amounts of mercury, cadmium and zinc

A simple solvent extraction procedure is reported for the sequential separation of mercury(II), cadmium(II) and zinc(II). Mercury is separated first using 1,3-diphenyl-2-thiourea in chloroform at an overall acidity of 0.3M HCl. Then cadmium separated using the same reagent at pH 10 into dichloromethane. The zinc which is remaining in the aqueous phase is then quantitatively extracted into toluene-cyclohexanol mixture using 2-mercaptobenzoxazole. Suitable stripping solutions have been proposed for the re-extraction of these metal ions for their subsequent estimations. The method has been made highly selective by the use of appropriate masking agents and has been applied in conjunction with estimation procedures for the determination of these metal ions in city waste incineration ash (CRM 176), mercuric chloride (A. R. grade) and in magnesium alloy samples.     

Decomposition of vegetables for determination of Zn,Cd, Pb and Cu by stripping voltammetry

A simple and accurate digestion method using nitric acid, perchloric acid and hydrogen peroxide has been developed for use in trace analysis for heavy metals in vegetables by differential pulse anodic stripping voltammetry. The recovery of the metals from the samples is lower if the hydrogen peroxide is omitted from the digestion mixture. Standard reference materials have been analysed satisfactorily by this method.     

Direct ICP-MS determination of trace and ultratrace elements in geological materials after decomposition in a microwave oven. Part II. Quantitation of Ba, Cs, Ga, Hf, In, Mo, Nb, Pb, Rb, Sn, Sr, Ta and Tl

A new method has been developed for the rapid determination of traces of Ba, Cs, Ga, Hf, In, Mo, Nb, Pb, Rb, Sn, Sr, Ta and Tl in silicate rocks and lake, stream and river sediments. The method involved dissolution of samples in a microwave oven by heating in a pressure decomposition Teflon vessel with a mixture of HF + HNO₃ + HCl + H₃BO₃ + EDTA followed by direct multielement determination using inductively coupled plasma-mass spectrometry (ICP/MS). The method is faster than conventional dissolution of samples by open vessel acid digestion and fusion and determination by instrumental methods. The accuracy and precision of the developed method were tested by replicate analyses of a number of international geochemical reference samples of established trace element contents. Satisfactory correlation with the “recommended” or “consensus” values was found and recoveries were in most cases 95–100%. New values for Ga, In, Nb and Tl in several international geochemical reference materials are first reported in this paper.     

Development of a rapid,multi-class method for the confirmatory analysis of anti-inflammatory drugs in bovine milk using liquid chromatography tandem mass spectrometry

A rapid liquid chromatography tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the simultaneous identification, confirmation and quantitation of seven licensed anti-inflammatory drugs (AIDs) in bovine milk. The method was validated in accordance with the criteria defined in Commission Decision 2002/657/EC. Two classes of AIDs were investigated, corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). The developed method is capable of detecting and confirming dexamethasone (DXM), betamethasone (BTM), prednisolone (PRED), tolfenamic acid (TLF), 5-hydroxy flunixin (5-OH-FLU), meloxicam (MLX) and 4-methyl amino antipyrine (4-MAA) at their associated maximum residue limits (MRLs). These compounds represent all the corticosteroids and NSAIDs licensed for use in bovine animals producing milk for human consumption. These compounds have never been analysed before in the same method and also 4-methyl amino antipyrine has never been analysed with the other licensed NSAIDs. The method can be considered rapid as permits the analysis of up to 30 samples in one day. Milk samples are extracted with acetonitrile; sodium chloride is added to aid partition of the milk and acetonitrile mixture. The acetonitrile extract is then subjected to liquid–liquid purification by the addition of hexane. The purified extract is finally evaporated to dryness and reconstituted in a water/acetonitrile mixture and determination is carried out by LC–MS/MS. Decision limit (CCα) values and detection capability (CCβ) values have been established for each compound.     

Matrix effects of leachates in the determination of volatile priority pollutants by headspace analysis

Summary In order to investigate the matrix effects of a hazardous waste landfill leachate in the analysis of priority pollutants by headspace gas chromatography, spiking experiments were performed (a) with the untreated leachate, (b) with the leachate after separation of oil and (c) with blanc water samples as a reference. A standard mixture containing volatile chlorinated hydrocarbons, benzene and alkylated benzenes (100–200 g) were spiked into 50 ml-samples of (a)–(c). The samples were thermostated at 40°C for 20 min and analyzed by headspace GC. Serious matrix effects were observed for all reference compounds, resulting in significant enhancement or depression of the corresponding peak areas compared with the spiked water control samples. The data sets are discussed with respect to the contents of leachate oil and chloride. From the findings of this study, recommendations for the application of headspace analysis to leachates are given.     

Determination of cadmium using radiochemical neutron activation analysis

A method has been developed for the determination of cadmium in samples of food and biological materials using neutron activation analysis with radiochemical separation. The irradiated sample is digested in presence of cadmium carrier, with a nitric-perchloric mixture, evaporated to dryness, dissolved in 6M HCl and placed onto an ion exchange column loaded with Dowex 1-X8 resin in chloride form and conditioned with HCl 6M. The cadmium is retained in the resin. After a washing procedure with several portions of HCl of decreasing concentration, the cadmium is eluted with an ammonia-ammonium chloride buffer. The activity of ^115mIn which is in equilibrium with ¹¹⁵Cd, is measured using a NaI(Tl) well type detector. The method has been evaluated by analyzing certified reference materials with cadmium concentrations covering a range of 0.020 to 200 mg^.kg^-1. The agreement of the results with the certified values is within 95%, which gives an indication of the sensitivity and accuracy of the proposed method.     

Separation and concentration of molybdenum(VI) and tungsten(VI) with chelating ion-exchange resins containing sulphur ligands

Three chelating ion-exchange resins based on macroreticular polyacrylonitrile-divinylbenzene copolymers with thioglycollic acid and cysteine as functional groups have been tested for separation of molybdenum(VI) and tungsten(VI). On a short column of the thioglycollic acid resin, molybdenum(VI) and tungsten(VI) can be selectively sorbed from pH-4.3 acetate buffer and eluted with 2M hydrochloric acid and a mixture of 0.1M sodium hydroxide and 0.1M sodium chloride, respectively, with quantitative recovery even at very low concentrations. Simulated sea-water samples have been analysed.     

Potentiometric determination of chloride in inorganic orthophosphates in citrate-buffered media

The chloride content of some inorganic orthophosphates and phosphate rock samples has been determined in a medium buffered to pH 2.5 with a mixture of perchloric acid, citric acid and trisodium citrate. The method has been compared with an earlier method which employed a mixture of perchloric acid, citric acid and triethanolamine. The present method is of similar reproducibility and does not suffer from decomposition of the reagents. The interference patterns of several metals are discussed.     

Researches on 2, 1, 3-thia- and selenadiazole

Depending on the reaction conditions, benzo-2, 1, 3-selenadiazole (I), dichlorodimethyl ether and aluminum chloride react to give a complex IV, or else 4-chloromethyl-(V) or 4, 7-di(chloromethyl) benzo-2, 1, 3-selenadiazole (VI). 5-(II) and 4-methylbenzo-2,l,3-selenadiazole(III) are chloromethylated by dichlorodimethyl ether in the presence of chlorosulfonic acid. Compound II is converted mainly into 5-methyl-4-chloromethylbenzo-2, 1, 3-selenadiazole(VII) or a mixture of three possible isomers VII, VIII, and IX, depending on the amount of base or pseudo-base in the reaction mixture. Ill gives mainly 4-methyl-7-chlorornethylbenzo-2, 1, 3-selenadiazole(X), independent of the presence of base. The structures of the chloromethylation products are shown by reductive splitting to o-diamides, and chromatography of the latter in the presence of reference spots. The high reactivity of the chlorine in the chloromethyl group made it possible to obtain new derivatives by replacing it with a hydroxyl, cyano, or thiocyano group.For Part XL see [1].     

Determination of total urinary mercury by on-line sample microwave digestion followed by flow injection cold vapour inductively coupled plasma mass spectrometry or atomic absorption spectrometry

The total mercury content in urine was determined by inductively coupled plasma mass spectrometry with the so-called cold vapour method after on-line oxidative treatment of the sample in a microwave oven (FI-MW-CV-ICPMS). Use of a KBr/KBrO(3) mixture, microwave digestion, and the final oxidation with KMnO(4), assure the complete recovery of the organic forms of Hg which would be difficult to determine otherwise if using only the CV-ICPMS apparatus. Quantitative recoveries were obtained for phenyl Hg chloride (PMC), dimethyl Hg (DMM), Hg acetate (MA) and methyl Hg chloride (MMC). Use of automatic flow injection microwave systems (FI-MW) for sample treatment reduces environmental contamination and allows detection limits suitable for the determination of reference values. Since no certified reference materials were commercially available in the concentration ranges of interest, the accuracy of the proposed procedure has been assessed by analysing a series of urine samples with two independent techniques, ICP-MS and AAS. When using the FI-MW-CV-ICP-MS technique, the detection limit was assessed at 0.03microg/L Hg, while with FI-MW-CV-AAS it was 0.2microg/L Hg. The precision of the method was less than 2-3% for FI-MW-CV-ICP-MS and about 3-5% for FI-MV-CV-AAS at concentrations below 1microg/L Hg. These results show that ICP-MS can be considered as a "reference technique" for the determination of total urinary Hg at very low concentrations, such as are present in non-exposed subjects.     

Flow injection spectrophotometric determination of calcium, phosphate and chloride ions in milk.

Flow injection procedures for the determination of calcium, phosphate and chloride ions in milk samples are described. The reactions are based on the formation of coloured complexes and their spectrophotometric monitoring. A sample pre-treatment with acetate buffer was carried out owing to the complexity of the sample matrix. For chloride, a rapid and reliable automated procedure for direct measurement of its content in milk (using a dialyser to eliminate interferences) is also described. After optimizing the sample pre-treatment and flow injection variables, the procedures were applied to commercial milk; the results obtained agreed satisfactorily with those of the reference methods. With 50 mm3 samples, a working range of 0-15 ppm for calcium, 50-150 ppm for phosphate and 5-100 ppm for chloride is covered with a precision of better than 1.1%. The sample throughput was higher than 50 samples h-1. These preliminary experiments are the basis for the automation of the determination of calcium, phosphate and chloride ions using a computer-controlled, self-designed and laboratory-built autoanalyser.     

Near 100% selectivity in anion exchange reactions of layered zinc hydroxy nitrate

The anionic clay, zinc hydroxy nitrate was found to selectively intercalate fluoride ions from a mixture of halide ions and chloride ions from a mixture of chloride, bromide and iodide ions. In a binary mixture of chloride and bromide ions, the selectivity for chloride ions was very high (94%) even when the bromide concentration was eight times in excess. The selectivity was achieved in both concentrated and dilute salt solutions. The trend in selectivity observed here is different from what has been observed for layered double hydroxides.     

Simultanbestimmung von Si, Mn, P, Cu, Al, Ni, Cr, Mo, V, Ti, Co und As in St?hlen mit ICP-AES

Summary A universal method for quantitative analysis of twelve elements in low-alloy steels is described. The samples are digested in a mixture of sulfuric-/nitric acid/ammonium peroxodisulfate. Si, Mn, P, Cu, Al, Ni, Cr, Mo, V, Ti, Co, As are determined in solution by ICP-AES. The procedure was tested with NBS and BCS reference samples. The analytical results are in good agreement with the certified values. With slight modifications, the method is applicable to the analysis of high-alloy steel samples.     

Gas chromatography analysis of organophosphorous pesticides in plant samples

Summary The work presents a GC method for the determination of six organophosphorous pesticide residues in cabbage. Chopped cabbage was blended with acetone, then extracted with the mixture of n-hexane:methylene chloride (1:1). The extract was purified on a GPC column packed with BioBeads SX-3 gel. The pesticides were eluted with the mixture of methylene chloride:cyclohexane (1:1) at the flow rate of 0.5 mL min⁻¹. After concentrating the extract was analysed by GC. Nearly 100 samples of cabbage were analysed; trace residues of dimethoate (about 0.05 ppm) were found in 10 samples. The average recoveries of the pesticides were above 80% with a relative standard deviation mostly less than 10%. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

Flame emission studies of several metal chlorides with vapor-phase sampling

A method is described for the production of spectra of aluminum chloride, iron(III) chloride, silicon tetrachloride and titanium tetrachloride vapors by flame emission spectrometry. The aluminum and iron(III) chloride vapors were prepared by heating solid samples in reaction flasks; silicon and titanium tetrachlorides have sufficient vapor pressures at ambient temperatures to produce vapor-phase samples. Techniques have been developed to introduce the sample into the flame as a vapor, and to accommodate a large concentration of sample while requiring minimum preparation. Spectra were obtained individually and as a mixture over 240–600 nm. The analytical wavelength was chosen for each element, and 10-s integrations were made by utilizing a microcomputer to slew rapidly to the line of interest, hold for 10 s on the emission line, move off wavelength, hold for a 10-s background measurement and slew rapidly to the next line of interest. The microcomputer was also used to digitize and display the number of photons counted.     

Catalytic Spectrophotometric Determination of Rhodium in The Rhodium-Potassium Periodate-Ethylrhodamine B

The method of kinetic spectrophotometry for determination of trace Rh(Ⅲ) had been reported by reference. We have discovered that trace the Rh(Ⅲ) catalyze the decolorating oxidizine reaction of ethylrhodamine B by potassium periodate on heating in phosphoric acid and sodium chloride medium, the reaction rate on log(A₀/A) values is linear over relatively range of concentration of Rh(Ⅲ). Hence a new catalytic spectrophotometric method for determination of trace Rh(Ⅲ) has been established. The method is simple,rapid and reproducible. The method has been used to determine trace Rh(Ⅲ) in actual samples with satisfactory results.     

Preconcentration of lead in biological matrices for graphite furnace atomic absorption spectrometry

Lead was transferred by a two-step extraction procedure from complicated biological matrices into an aqueous solution. Thereafter, lead could be accurately determined in the aqueous solution without interference by graphite furnace atomic absorption spectrometry (GFAAS). Biological samples were digested sequentially by a mixture of sulphuric acid and nitric acids and a strong oxidant, potassium peroxodisulphate. Lead was extracted by dithiocarbamate in chloroform from the digest solution and subsequently back-extracted into a mercury(II) solution. Matrix materials such as chloride, phosphate and sulphate, which were known to cause serious interference in the determination of lead by GFAAS, could be eliminated in the preconcentration procedure. Close to 90% recovery of lead was achieved. The proposed procedure was applied for the analysis of several NBS biological standard reference materials containing lead in the mg kg^?1 range and satisfactory results were obtained.     

Two-dimensional fluorescence correlation spectroscopy II: spectral analysis of derivatives of anthracene and pyrene in micellar solutions

Generalized two-dimensional (2D) correlation spectroscopy has been applied to the analysis of fluorescence spectra in two micellar systems: (1) a mixture of pyrene and 1,3,6,8-pyrenetetrasulfonic acid in the cationic micellar solutions of cetyltrimethylammonium chloride (CTAC) and (2) a mixture of pyrene and 9-anthracencepropionic acid in anionic micellar solutions of sodium dodecyl sulfate (SDS). Fluorescence quenching is employed as a perturbation mode for causing intensity changes in fluorescence bands (quenching perturbation). Iodide ion (I-) is used as a quencher in the former system, and cetyl pridinium chloride (CPC) is used in the latter. Vibronic bands in the complicated fluorescence spectra of the mixture of the analytes were successfully resolved. It is shown that asynchronous maps are especially useful for spectral resolution enhancement when the quenching perturbation is employed in 2D fluorescence correlation spectroscopy. Furthermore, the information about the order of response of the bands to quenching is obtained by comparing the signs of synchronous and asynchronous cross-peaks.