Evaluation of vapor generation for the determination of nickel by inductively coupled plasma-atomic emission spectrometry

Volatile species of Ni were generated by merging acidified aqueous samples and sodium tetrahydroborate(III) in a continuous flow system. The gaseous analyte was subsequently introduced via a stream of Ar carrier into the inlet tube of the plasma torch. Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for detection. The operating conditions (chemical and physical parameters) and the concentrations of different acids were evaluated for the efficient generation of Ni vapor. The detection limit (3 sigma(blank)) was 1.8 ng mL(-1). The precision (RSD) of the determination was 4.2% at a level of 500 ng mL(-1) and 7.3% for 20 ng mL(-1) (n=10). The efficiency of the generation process was estimated to be 51%. The possible interfering effect of transition metals (Cd, Co, Cu, Cr, Fe, Mn, Zn), hydride forming elements (As, Ge, Pb, Sb, Se, Sn, Te), and Hg on Ni signal was examined. This study has demonstrated that Ni vapor generation is markedly free of interferences.     

Validated capillary electrophoretic method for the analysis of ivermectin in plasma after intragastric administration in pigs and horses

A capillary electrophoretic (CE) method has been developed for the determination of ivermectin (CAS 70288-86-7), a new generation drug with antiparasitic activity, in pig and horse plasma. The method was statistically validated for its linearity, accuracy, precision and selectivity. The linear range was from 1 to 30 ng mL(-1) with correlation coefficients greater than 0.999. The limit of detection was 0.3 ng mL(-1), while the quantitative limit was 1 ng mL(-1), using a 0.5 mL sample size. The validated procedure was used to determination of pharmacokinetic parameters of ivermectin after ingestion of 0.1 mg for pigs and 0.2 mg dose per kg body weight for horses, respectively. Studies were performed on a group of eight pigs and six horses. There were no significant differences between pigs and horses in any of the estimated pharmacokinetic parameters.     

ICP-AES法测定肝癌组织中微量元素的研究

为建立电感耦合等离子体原子发射光谱(ICP-AES)法测定肝癌组织中Mg、Na、Ca、Mn、Fe、Co、Cu、Zn等8种微量元素的方法,样品用HNO3+HC lO4经微波消解后直接进样,用ICP-AES法同时测定了上述元素,对分析谱线、基体元素和等离子体参数等进行了讨论,确定了实验的最佳测定条件。结果表明,8种微量元素的检出限在3.6~26.0 ng/mL之间,回收率在93.8%~106.2%之间,相对标准偏差(RSD)小于4.05%。     

Application of high-surface-area ZrO2 in preconcentration and determination of 18 elements by on-line flow injection with inductively coupled plasma atomic emission spectrometry

A flow-injection analysis (FIA) system incorporating a micro-column of ZrO2 has been used for the development of an on-line multi-element method for the simultaneous preconcentration and determination of Al, Bi, Cd, Co, Cr, Cu, Fe, Ga, In, Mn, Mo, Ni, Pb, Tl, V, Sb, Sn, and Zn by inductively coupled plasma atomic emission spectrometry (ICP-AES). The conditions for quantitative and reproducible preconcentration, elution, and subsequent on-line ICP-AES determination were established. A sample (pH 8) is pumped through the column at 3 mL min(-1) and sequentially eluted directly into the ICP-AES with 3 mol L(-1) HNO3. With a sample volume of 100 mL and an elution volume of 1 mL signal enhancement 100 times better than for conventional continuous aspirating systems was obtained for the elements studied. The reproducibility (RSD %) of the method at the 10 ng mL(-1) level in the eluate is acceptable - less than 8% for five replicates. Recoveries between 95.4% and 99.9% were obtained for the elements analysed. ZrO2, with a specific surface area of 57 m2 g(-1) and a capacity of approximately 5 mg g(-1) for the elements studied, was synthesized by hydrolysis of ZrCl4. The preconcentration system was evaluated for several simple synthetic matrices, standard water samples and synthetic seawater. The effect of foreign ions on the efficiency of preconcentration of the elements studied was investigated. The application of a micro-column filled with high-surface-area ZrO2 and flow injection inductively coupled plasma atomic emission spectrometry enables preconcentration and simultaneous determination of 18 elements at low concentrations (ng L(-1)) in different water samples.     

Sequential determination of tin, arsenic, bismuth and antimony in marine sediment material by inductively coupled plasma atomic emission spectrometry using a small concentric hydride generator and L-cysteine as prereductant

A hydride generation system using a small concentric hydride generator combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) was established to determine tin, arsenic, bismuth and antimony in a marine sediment material with L-cysteine as a pre-reductant. Influences of concentrations of three kinds of acids (HCl, HNO₃ and HClO₄), L-cysteine, and sodium tetrahydroborate(III) as well as sodium hydroxide were investigated. The interferences from transition ions were found to be insignificant for determination of the four elements in presence of L-cysteine. Under optimized conditions the detection limits were 0.6 ng/mL for arsenic(III), 0.8 ng/mL for antimony(III), 1.7 ng/mL for tin(IV), and 1.2 ng/mL for bismuth(III). The method was applied to determine the four elements in standard marine sediment materials and the results were in agreement with certified values.     

Optimization of electrochemical hydride generation in a miniaturized electrolytic flow cell coupled to microwave-induced plasma atomic emission spectrometry for the determination of selenium

The optimization of a continuous flow system for electrochemical hydride generation coupled to microwave-induced plasma atomic emission spectrometry (MIP-AES) for the determination of Se is presented. A small electrolytic cell with a porous glassy carbon working electrode was used for hydride generation. When using an Ar MIP operated in a TE101 cavity a detection limit of 0.6 ng mL(-1) (3sigma) could be achieved. The calibration curve was linear up to 1 microgram mL(-1). A standard deviation of less than 2% (10 replicate analyses) could be achieved. It was shown that interferences of transition metals are of the same order of magnitude as with a larger electrolysis cell described earlier, and light elements hardly caused any signal depression as tested. It was possible to distinguish between Se(IV) and Se(VI) species and seleno-DL-methionine, because under optimized conditions of an electrolysis current of 10 mA, a microwave power of 210 W, an Ar flow rate of 15 L h(-1) and a sample flow rate of 2.5 mL min(-1) only Se(IV) was transformed to H2Se and transferred into the plasma. Finally, the possibility of an electrochemical pre-enrichment was shown to enable it to further decrease the detection limit.     

Sequential determination of tin, arsenic, bismuth and antimony in marine sediment material by inductively coupled plasma atomic emission spectrometry using a small concentric hydride generator and L-cysteine as prereductant

A hydride generation system using a small concentric hydride generator combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) was established to determine tin, arsenic, bismuth and antimony in a marine sediment material with L-cysteine as a pre-reductant. Influences of concentrations of three kinds of acids (HCl, HNO₃ and HClO₄), L-cysteine, and sodium tetrahydroborate(III) as well as sodium hydroxide were investigated. The interferences from transition ions were found to be insignificant for determination of the four elements in presence of L-cysteine. Under optimized conditions the detection limits were 0.6 ng/mL for arsenic(III), 0.8 ng/mL for antimony(III), 1.7 ng/mL for tin(IV), and 1.2 ng/mL for bismuth(III). The method was applied to determine the four elements in standard marine sediment materials and the results were in agreement with certified values. Received: 4 September 1997 / Revised: 14 October 1997 / Accepted: 7 November 1997     

Reagent injection FIA system for lead determination by hydride generation - quartz-tube atomic absorption spectrometry

A method is proposed for the determination of lead by generation of its hydride and detection by quartz-tube AAS using a reagent injection FIA system based on the injection of sodium tetrahydroborate. Lead hydride generation was carried out using a combination of 0.5 M nitric acid, 10% m/ v hydrogen peroxide and 10% m/ v sodium tetrahydroborate. The characteristic concentration obtained was 3.1 ng mL(-1) and the detection limit was 2.6 ng mL(-1) for an injected volume of 0.125 mL of tetrahydroborate.     

Simultaneous derivative spectrophotometric determination of zinc and cadmium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride.

A selective and sensitive derivative photometric method has been developed for the determination of trace amounts of Zn2+ with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant. The molar-absorption coefficient and analytical sensitivity of the 1:2 complex at 554 nm are 1.19 x 10(5) L mol(-1) cm(-1) and 0.56 ng mL(-1), respectively. The detection limit is 1.96 x 10(-2) ng mL(-1) and Beer's law is valid in the 0.02-0.66 microg mL(-1) range of Zn2+. The developed derivative procedure, using the zero-crossing measurement approach, is applied for the rapid and selective simultaneous determination of Zn2+ and Cd2+ in the range of 0.06-0.66 and 0.20-1.60 microg mL(-1), respectively. Complex matrices, including reference materials, environmental and biological samples and synthetic mixtures, have been successfully analyzed for trace amounts of the two metal ions.     

Determination of diclofenac in plasma by high-performance liquid chromatography with electrochemical detection

A reversed-phase high-performance liquid chromatographic method with electrochemical detection for the quantitative determination of diclofenac potassium in plasma was developed. Naproxen was used as the internal standard. The drug and internal standard were isolated from plasma by extraction with dichloromethane and 2 M hydrochloric acid. Chromatographic separation was performed on a C18 column with methanol-water (68:32, v/v) adjusted to pH 3.2 with phosphoric acid as mobile phase. The oxidation potential for detection was established by constructing a voltammogram for diclofenac. The quantification limit for diclofenac in plasma was 5 ng mL(-1). Linearity of the method was confirmed in the range 5-2000 ng mL(-1), correlation coefficient 0.9998. Within-day relative standard deviations (RSDs) ranged from 0.66 to 14.00% and between-day RSDs from 0.59 to 15.78%. The method was successfully applied for the determination of pharmacokinetic parameters after ingestion of a 50 mg dose of diclofenac. Studies were performed on 18 healthy volunteers of both sexes.     

氢化物发生-原子荧光光谱法同时测定高纯铟中As、Sb

研究了氢化物发生-原子荧光光谱法测定高纯铟中微量As、Sb元素的条件,选择了适宜的反应条件以及仪器的最佳工作条件,考察了铟基体对被测元素的干扰,采用基体匹配的方法消除干扰,建立了氢化物发生-原子荧光光谱法测定高纯铟中微量的As、Sb的分析方法。As、Sb的检出限分别为0.18和0.28 ng/mL,测定下限为1.2×10-5和1.9×10-5,相对标准偏差分别为1.9%和1.7%,回收率为97.4%和103%,适用于5～6 N高纯铟中微量As、Sb的测定。     

Solid phase extraction using a sulfoxide adsorbent for preconcentration and separation of Hg(II) in natural water followed by ICP-MS measurements

A separation and preconcentration method based on solid-phase extraction using sulfoxide adsorbent was developed for the determination of Hg(II) in natural water samples by inductively coupled plasma mass spectrometry (ICP-MS). The sulfoxide adsorbent was packed into a commercially available syringe-driven column (with a bed volume of 1.0 mL), which permitted off-line sample loading and on-line elution/measurement. The optimized operating conditions were as follows: sample condition for Hg(II) adsorption, 0.5% HCl; sample-loading flow rate, 10 mL min(-1); eluent for recovering Hg(II), 1% cysteine water solution. A test using multi-element mixed solution showed that most trace elements in natural water, except for Bi, could be completely separated from Hg(II). The recoveries of Hg(II) were 99.0 ± 3.2 and 100.7 ± 4.3%, respectively, when 0.64 and 0.16 ng mL(-1) of Hg(II) were added into the test sample. The detection limit of Hg(II) using a quadrupole ICP-MS after 10-fold preconcentration was 1.5 pg mL(-1). The blank value was 2.8 ± 0.5 pg mL(-1).     

Electrothermal vaporization in inductively coupled plasma atomic emission spectrometry for direct multielement analysis of food samples with slurry sampling

Slurry sampling followed by electrothermal vaporization (ETV) was used as sample introduction technique in inductively coupled plasma atomic emission spectrometry (ICP-AES) for the direct determination of trace elements in food samples. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote vaporization and the transportation of analytes. The main factors affecting the analytical signals were investigated in detail. Under optimum operating conditions, the detection limits (DL) for this method varied from 1.8 (Cu) to 215 ng/mL (Zn), while the relative standard deviations (RSD) were in the range 2.6% (Cu)-7.2% (Zn). The proposed method was successfully applied to the direct determination of trace amounts of V, Cu, Cr, Fe, Zn, and La in rice without any chemical pretreatment. The precision was evaluated by analyzing a standard reference material (tea leaves, GBW 07605) and comparing the results from this method with results obtained by pneumatic nebulization (PN) ICP-AES after the wet-chemical decomposition of the same sample.From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 286–290.Original English Text Copyright © 2005 by Chen.This article was submitted by the author in English.     

Use of chelating resins and inductively coupled plasma mass spectrometry for simultaneous determination of trace and major elements in small volumes of saline water samples

For some saline environments (e.g. deeply percolating groundwater, interstitial water in marine sediments, water sample collected after several steps of fractionation) the volume of water sample available is limited. A technique is presented which enables simultaneous determination of major and trace elements after preconcentration of only 60 mL sample on chelating resins. Chelex-100 and Chelamine were used for the preconcentration of trace elements (Cd, Cu, Pb, Zn, Sc) and rare earth elements (La, Ce, Nd, Yb) from saline water before their measurement by inductively coupled plasma mass spectrometry. Retention of the major elements (Na, Ca, Mg) by the Chelamine resin was lower than by Chelex; this enabled their direct measurement in the solution after passage through the resin column. For trace metal recoveries both resins yield the same mass balance. Only Chelex resin enabled the quantitative recovery of rare earth elements. The major elements, trace metals and rare earth elements cannot be measured after passage through one resin only. The protocol proposes the initial use of Chelamine for measurement of trace and major elements and then passage the same sample through the Chelex resin for determination of the rare earth elements. The detection limit ranged from 1 to 12 pg mL(-1). At concentrations of 1 ng mL(-1) of trace metals and REE spiked in coastal water the precision for 10 replicates was in the range of 0.3-3.4% (RSD). The accuracy of the method was demonstrated by analyzing two standard reference waters, SLRS-3 and CASS-3.     

电感耦合等离子体发射光谱法测定稀土发火合金中铁、镁、铜和锌

采用盐酸辅以加热的方式处理稀土发火合金样品,以电感耦合等离子体原子发射光谱法测定稀土发火合金中铁、镁、铜和锌含量。采用矩阵模拟实验优化分析谱线,利用多点定标校正曲线法计算测量结果。在最佳实验条件下,稀土发火合金中的基体元素对待测元素的测定结果无明显影响,各元素在检测范围内线性关系良好,相关系数均为0.999 9,方法检出限为0.001~0.010μg/m L。测定结果的相对标准偏差为1.10%~1.75%(n=11),样品加标回收率在96.00%~104.05%之间。该方法简便、快速且具有较高的灵敏度,适用于稀土发火合金中铁、镁、铜、锌等非稀土元素的测定。     

Stereoselective determination of demethyl- and didemethyl-citalopram in rat plasma and brain tissue by liquid chromatography with fluorescence detection using precolumn derivatization

A rapid and sensitive HPLC enantioselective method with fluorescence detection was developed to determine (-)-(R) and (+)-(S) enantiomers of the metabolites of citalopram, demethyl- and didemethyl-citalopram in plasma and brain tissue. This assay involves pre-column chiral derivatization with (-)-(R)-1-(1-naphthyl)ethyl isocyanate followed by separation on a normal-phase silica column. The developed liquid-liquid extraction procedure permits quantitative determination of analytes with recoveries ranged between 81 and 88% with intra- and inter-day relative standard deviations less than 10.5%. Linearity was obtained over the concentration range 5-1000 ng/mL and 100-10,000 ng/g for spiked drug-free plasma and brain tissue, respectively, with detection limits lower than 2.1 ng/mL and 42.8 ng/g.     

Simultaneous determination of Cd, Cu, Mn, Ni, Pb and Zn in nail samples by inductively coupled plasma mass spectrometry (ICP-MS) after tetramethylammonium hydroxide solubilization at room temperature: comparison with ETAAS

A simple method is described for the determination of Cd, Cu, Mn, Ni, Pb and Zn in nails by using inductively coupled plasma mass spectrometry (ICP-MS) or electrothermal atomic absorption spectrometry (ETAAS). Prior to analysis, 10-20 mg of nail samples were accurately weighed into (15 mL) conical tubes. Then, 1 mL of 25% (w/v) tetramethylammonium hydroxide (TMAH) solution was added to the samples, incubated at room temperature overnight and then further diluted to 10 mL with 1% (v/v) HNO(3). After that, samples were directly analyzed. Rhodium was used as internal standard for ICP-MS analysis. Method detection limits (3 s, n=20) were 0.1, 3.0, 1.0, 4.5, 1.5, 5.0 ng g(-1) for Cd, Cu, Mn, Ni, Pb and Zn, respectively for ICP-MS, and 24, 26, 30, 143, 130 and 1000 ng g(-1), respectively for ETAAS. The key issue addressed here is the elimination of the acid digestion prior to analysis. Moreover, with the use of the proposed method there is a considerable improvement in the sample throughput comparing to the traditional methods using microwave-assisted acid sample digestion prior to analysis. For validation purposes, six ordinary nail samples were solubilized and then directly analyzed by ICP-MS and ETAAS, with no statistical difference between the two techniques at 95% level on applying the t-test.     

Determination of artemether in plasma and whole blood using HPLC with flow-through polarographic detection

An HPLC method with polarographic detection for the trace determination of artemether in plasma and whole blood was developed and applied to pharmacokinetic and clinical pharmacological studies. The method showed high sensitivity and selectivity because of the easy reduction of the peroxide linkage of artemether at the mercury drop electrode. The detection limit was 10 ng and the detector response was linear over the range of 10 ng to 1 microgram artemether injected onto the column. The largest relative standard deviation of 10 replicate measurements of standard solutions (concentrations of 10 ng/mL-1 microgram/mL) was 8%. The recovery from whole blood and plasma of added drug (concentrations of 15-480 ng/mL) was 71-100%.     

Capillary gas chromatographic analysis of pyrrolidinedithiocarbamate metal chelates

Pyrrolidinedithiocarbamate (PDTC) chelates of Zn(II), Cu(II), Ni(II), Co(III), Fe(III), Mn(II), Cr(III), and VO(II) were analysed by capillary GC on a DB-1701 column (30 m x 0.25 mm id) with flame ionisation detection (FID). Linear calibrations were attained within "1-30 microg/mL" for Ni(II), Fe(III), Mn(II), Cr(III), Cu(II), and VO(II), and within "2-50 microg/mL" for Co(III) and Zn(II). The limits of detection were in the "150-500 ng/mL" range, corresponding to 15-50 pg amounts reaching the FID system. The optimised method was applied to the determination of Cu(II) and Ni(II) in coins, and that of Zn(II), Cu(II), Ni(II), Fe(III), Mn(II), Cr(III), and VO(II) in pharmaceutical preparations with relative standard deviations within 1.1-5.2%. The results obtained are in good agreement with sewage water samples and the declared values for the pharmaceutical formulations, or with the results of AAS of metal contents in coins, pharmaceutical preparations, and sewage water samples.     

The use of thermal lensing for the determination of pyrogens

Based on the optimized spectrophotometric determination of pyrogens (of various classes ( p-aminophenol and endotoxins), thermal lensing was applied to the determination of these substances at the submicrogram level. The limit of detection of p-aminophenol, a pyrogenic impurity in pharmaceutical formulations of paracetamol, by reaction with resorcinol in alkaline solutions is 100 ng mL(-1). Phloroglucinol was considered as an analog of resorcinol as a reagent in this reaction. The conditions of spectrophotometric determination of pyrogenic lipopolysaccharides (endotoxins) by ion-pair formation with methylene blue (the limit of detection is 100 ng mL(-1)), by ion-pair formation with Stains-All (1-ethyl-2-[3-(1-ethylnaphtho[1,2-d]thiazolin-2-ylidene)-2-methylpropenyl]naphtho[1,2-d]thiazolium bromide) (the limit of detection is 500 ng mL(-1)), and by reaction of 2-keto-3-deoxyoctonic acid with thiobarbituric acid (the limit of detection is 800 ng mL(-1)) were proposed. The optimized procedure for 2-keto-3-deoxyoctonic acid was applied for thermal lensing that provided a decrease in the limit of detection to 70 ng mL(-1) and was also used for lipopolysaccharide determination in the endotoxin standard from E. coli.