Total-reflection X-ray fluorescence determination of cobalt and mercury in water using preconcentration on a polyurethane foam sorbent

A technique for X-ray fluorescence determination of cobalt and mercury in water using static and dynamic concentration in the form of thiocyanate and iodate complexes on polyurethane foam sorbents based on ethers is suggested. The possibility of the measurement of the X-ray fluorescence signal of analytes in the total external reflection mode, both in eluates and directly in the sorbent phase, is considered. The suggested approach allows one to improve the sensitivity of cobalt and mercury determination in water by 2–4 orders of magnitude in comparison with the classical sorption X-ray fluorescence techniques.     

Direct X-ray fluorescence detection of mercury on polyurethane foam sorbents

An improved method for conducting a sorption X-ray fluorescence analysis of mercury (II) in water with static and dynamic preconcentrations in the form of iodide complexes on polyurethane foam sorbents based on ethers has been proposed. It was shown that optimizing the conditions of measuring analytical signals enabled a significant (one order of magnitude or more) increase in the sensitivity of the detection of X-ray fluorescence and widening of the linear range of graduation dependence.     

The extraction and determination of thiocyanate complexes by use of polyurethane foam

Metal thiocyanate solutions were extracted with polyether-type polyurethane foam and the metal contents determined by X-ray fluorescence. Iron, cobalt and zinc were extracted individually and collectively from 3.0M NH(4)Cl and 1.0M NH(4)SCN solutions. Similarly platinum and palladium could be simultaneously extracted from 0.12MNH(4)SCN and 5.0MNH(4)Cl for subsequent determination. The metal extractions were more than 95% complete and the determination of one metal was not affected by the presence of the others.     

Chromotropic acid-functionalized polyurethane foam: A new sorbent for on-line preconcentration and determination of cobalt and nickel in lettuce samples

A chromotropic acid-functionalized polyurethane foam has been developed for use in an on-line preconcentration system for cobalt and nickel determination. The packing material was prepared by covalent coupling of chromotropic acid with the polyurethane foam through an azo group. Co and Ni ions were sorbed in the mini-column, from which they could be eluted directly to the nebulizer-burner system of a flame atomic absorption spectrometer. Elution of cobalt and nickel from the mini-column can be accomplished with 0.50 and 0.75 M HCl solutions, respectively. The enrichment factors obtained were 22 (Co) and 27 (Ni), for 60 s preconcentration time, and 57 (Co) and 59 (Ni), if a preconcentration time of 180 s was used. Under the optimum conditions, the proposed procedure allowed the determination of metals with detection limits of 0.43 (cobalt) and 0.52 microg/L (nickel), respectively, on using preconcentration periods of 180 s. The accuracy of the developed procedure was evaluated by analysis of the certified reference materials NIST 1515 Apple Leaves and NIST 1570a Spinach Leaves. The method was applied to the analysis of lettuce samples. The contents of cobalt in the samples analyzed varied from 0.75 to 0.98 microg/g. Nickel was not detected in the lettuce samples.     

Determination of arsenic by polyurethane foam extraction and X-ray fluorescence

A method based on extraction with polyurethane foam and determination by X-ray fluorescence has been developed for the determination of arsenic. Arsenic concentrations as low as 36 mug ml can be detected in 100 ml of aqueous solution.     

Analytical Application of Silica Gel Modified with Didecylaminoethyl-beta-Tridecylammonium Iodide

Sorption of a high molecular weight quaternary ammonium salt, didecylaminoethyl-β-tridecylammonium iodide (DDATD) on different types of sorbents was investigated. The nature of reagent adsorption on silica gel was examined by spectroscopic and computer methods. The sorption of anionic metal complexes of cobalt, copper, zinc and manganese on silica gel modified with DDATD was studied. The possibility of recovery of cobalt and copper thiocyanate complexes and their further atomic absorption determination is shown. Modified sorbent was applied to cobalt chemiluminescence and determined in natural water and a nickel preparation (detection limit, 2 μg/l.).     

Determination of heavy metal ions in environmental samples employing preconcentration on novel resins of polyurethane foam linked with o-Aminophenol or o-Hydroxyphenylazonaphthol

o-Aminophenol (AP) and its azo derivative with ß-Naphthol(Naph) is bonded to polyurethane foam (BPUF) and used as solid phase extractor of nickel, cadmium and zinc ions in aqueous solutions prior to their atomic absorption spectrometric determinations. The novel resins of polyurethane foam were characterised by density, elemental analysis, IR spectra and chemical stability. The parameters including pH, sample volume, matrix effects were investigated. The relative standard deviation (RSD) of the combined method of sample treatment, preconcentration and determination with atomic absorption spectrometry is generally lower than 10%. The limit of detection was found between 0.06 and 0.22?µg?L^?1. The procedure was used for determination of analyte ions in natural water samples, apple leaves and fish liver.     

Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer).The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF.The calculated detection limits in all cases were in the low ng mL^− 1 range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required.The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland.     

Determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by FAAS: Matrix effect control by multivariate technique

A new approach for the determination of cobalt, copper, iron, nickel and zinc in cemented tungsten carbides with cobalt as a binder by flame atomic absorption spectrophotometry (FAAS) is reported. Real samples were dissolved in phosphoric, hydrochloric and nitric acid. PTFE bomb or alternatively small amounts of HF were used for the enhancement of the recovery of the elements investigated. Synthetic samples were used for interference studies. Multiple linear regression was applied for the control of matrix effects and it proved to be very effective in the search for interfering elements. Using simple acid based standards, all investigated elements could be determined sequentially in a complex matrix by using an appropriate method of calculation. The method described has been succesfully applied to real type commercial samples. Results were compared with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) and X-ray fluorescence spectrometry (XRF), being in good agreement with each other and having relative standard deviations better than 5%.     

On-line preconcentration with different solid adsorbents for lead determination

An on-line column preconcentration method based on the combined use of ammonium O,O-diethyldithiophosphate and activated carbon or polyurethane foam as adsorbents has been developed for the determination of Pb in water samples. The complexed Pb was eluted with ethanol and determined by flame atomic absorption spectrometry. The optimum preconcentration conditions are given for each adsorbent. The enrichment factors were 63 and 294, and the detection limits (3sigma) 3 microg L(-1) and 0.8 microg L(-1), respectively, for the carbon and foam systems. When the optimized procedures were applied to the determination of Pb in water samples the recovery efficiency was > 96%.     

Indirect Determination of Phosphate by X-ray Fluorescence Spectrometry Using Polyurethane Foam

Abstract

An indirect X-ray fluorescence method for phosphate has been established based on the extraction of phosphomolybdate by polyurethane foam. The molybdenum, which is associated in a fixed ratio with phosphorus, is determined directly on foam, by X-ray fluorescence spectrometry.     

Direct determination of gallium on polyurethane foam by X-ray fluorescence

Gallium chloride is easily extracted from 6M HCl by comminuted polyether-type polyurethane foam. After the extraction step, the gallium absorbed by the PU foam can be quantitatively determined by X-ray fluorescence. A procedure for the direct determination of gallium absorbed by PU foam by XRFS is thus described. Gallium is determined at levels as low as 60 ng/ml (C(L)), with a calibration sensitivity of 424 cps ml/mug, within a linear range 0.1-2.30 mug/ml. The procedure investigated was successfully applied to determination of gallium in aluminum alloys, bauxite and industrial residue samples.     

Preconcentration of Polycyclic Aromatic Hydrocarbons on Polyurethane Foams and Their Determination in Waters with the Use of Luminescence and High-Performance Liquid Chromatography

A technique was developed for the sorption preconcentration of polycyclic aromatic hydrocarbons on polyurethane foams in the batch and dynamic modes providing their simultaneous quantitative extraction. A procedure was proposed for screening waters for polycyclic aromatic hydrocarbons based on the preconcentration of these compounds with polyurethane foam, determination of their total amount by the luminescence method, desorption of adsorbed compounds with acetonitrile, and determination of individual compounds in the eluate by high-performance liquid chromatography with fluorescence detection. The procedure was tested with model and real samples of water.     

Removal of organic pollutants from aqueous solution. V. Comparative study of the extraction, recovery and chromatographic separation of some organic insecticides using unloaded polyurethane foam columns

The concentration of dissolved insecticides in aqueous media was determined by chromatographic separation on polyurethane foam columns. The results of preliminary screening tests on the removal of insecticides by the unloaded polyurethane foam indicated that a reasonable percentage of the insecticides was retained on the foam. Therefore attempts were made to extract these compounds from aqueous media using foam columns. Various parameters affecting the retention and separation of these compounds were studied, including temperature, flow-rate, pH, insecticide concentration, shaking time, sample volume and eluting solvent. The complete separation and quantitative recovery of these compounds from the foam with acetone in a Soxhlet extractor were achieved. The method can be used to preconcentrate insecticides in tap water and modified to determine dissolved insecticides in industrial and natural waters. Polyurethane foam has a good capacity for use when large volume samples need to be handled and is an inexpensive sorbent compared to other known solid sorbents.     

电感耦合等离子体发射光谱法（ICP-OES）测定钴白合金中锗

建立了一种电感耦合等离子体发射光谱法（ICP-OES）测定钴白合金中锗含量的分析方法,确定了最佳实验条件,方法的检出限为0.043 μg/mL,对钴白合金中锗的测定结果与其他法结果一致,方法的相对标准偏差RSD在1.07 %~1.91 %（n=7）之间,样品的加标回收率在98.5 %~102.1 %之间。     

On-line preconcentration with different solid adsorbents for lead determination

An on-line column preconcentration method based on the combined use of ammonium O,O-diethyldithiophosphate and activated carbon or polyurethane foam as adsorbents has been developed for the determination of Pb in water samples. The complexed Pb was eluted with ethanol and determined by flame atomic absorption spectrometry. The optimum preconcentration conditions are given for each adsorbent. The enrichment factors were 63 and 294, and the detection limits (3σ) 3?μg?L^–1 and 0.8?μg?L^–1, respectively, for the carbon and foam systems. When the optimized procedures were applied to the determination of Pb in water samples the recovery efficiency was > 96%.     

Selective determination of cobalt using polyurethane foam and 2-(2-benzothiazolylazo)-2-p-cresol as a spectrophotometric reagent

The present work describes a selective, rapid and economical method for the determination of cobalt using the 2-(2-benzothiazolylazo)-p-cresol (BTAC) as a spectrophotometric reagent associated with a solid extraction on polyurethane foam. The BTAC reacts with Co(II) in the presence of Triton-X100 surfactant forming a green complex with maximum absorption at 615 nm. The reaction is used for cobalt determination within a pH range of 6.50-7.50, with an apparent molar absorptivity of 1.62 x 10(4) L mol(-1) cm(-1). Beer's Law is obeyed for a concentration of at least 1.60 microg ml(-1). A selective procedure is proposed for cobalt determination in the presence of Fe(II), Hg(II), Zn(II) and Cu(II) up to milligram levels using masking agents. Polyurethane foam is used for the preconcentration and separation of cobalt from thiocyanate media and this procedure is applied to its determination in nickel salts and steel alloys.     

Microdetermination of Trace Cobalt In Water By Direct Polyurethane From Thin-Layer Spectrophotometry

Abstract

Traces of cobalt in water sample are preconcentrated into a white thin-layer of a parallelpiped polyurethane foam, by the sorption of its thiocyanate complex from acidic medium.

The cobalt thiocyanate complex possesses a blue colour in the foam matrix which has a maximum absorption at 625 nm. the absorbance of the Dlue species is mesured directly in the foam matrix at 680 625 and 540 nm. with different media in the measuring cell. the net absorbance at 625 nm is calculated using a multiwavelength program, where the value of the blank is subtracted. Beer's law is obeyed in the concentration range 0.025-2.0 μg per dl with a detection limit of 25 μg per dl for a 100 ml sample volume. the method is specific for cobalt     

Reversed phase foam chromatography : Separation of iron from copper,cobalt and nickel in the tri-n-butyl phosphate-hydrochloric acid system

The separation of iron from cobalt, copper and nickel by reversed-phase foam chromatography was investigated. The distribution of Fe, Co and Cu in TBP-HCl and TBP(polyurethane foam)-HCl systems was measured. Iron can be separated from the three other metals on polyether-type polyurethane foam columns loaded with TBP. The break-through curve of iron on TBP (polyurethane foam) columns was measured. The column was found suitable for the separation of ⁵⁸Co and ⁵⁹Fe isotopes.     

电热鼓风干燥箱解脱–火焰原子吸收光谱法测定地质样品中金的含量

建立高海拔地区电热鼓风干燥箱解脱–火焰原子吸收光谱法测定地质样品中的金的方法。高海拔地区由于大气压低,水的沸点低,使得泡塑吸附金的解脱率不高。为了得到准确的分析结果,采用电热鼓风干燥箱代替水浴锅来解脱泡塑吸附金,优化后的解脱条件:解脱温度为105℃,解脱时间为30 min,在此条件下金的解脱率为91.19%。金的质量浓度在0.00~10.00μg/mL范围内与其吸光度呈良好的线性关系,相关系数r=0.999 6,方法检出限为0.012μg/mL。测定结果的相对标准偏差为2.15%(n=7),加标回收率为96.0%~102.5%。用该方法测定国家一级标准物质,测定结果与参考值相符。该方法准确、可靠,适用于高海拔地区地质样品中金的测定。