Determination of Hg in seawater by inductively coupled plasma mass spectrometry after on-line pre-concentration

A method for the determination of Hg in seawater by inductively coupled plasma mass spectrometry, after an on-line separation and pre-concentration, is described. The matrix separation was accomplished by retention of the Hg complex with the ammonium salt of O,O-diethyl dithiophosphoric acid on C₁₈ immobilized on silica in a micro-column. Before pre-concentration, the seawater sample was acidified with HNO₃ to 0.14 mol l⁻¹. Methanol was used as the eluent, which was introduced into the conventional pneumatic nebulizer of the instrument. External calibration with aqueous analytical solutions, submitted to the same procedure, was used. An enhancement factor of 16 was obtained, and the limit of detection was 5 ng l⁻¹. The sample consumption was 2.3 ml per determination, and the sampling frequency was 21 h⁻¹. The accuracy was tested by comparison with vapor generation inductively coupled plasma mass spectrometry. The agreement between the Hg concentrations measured by the two methods in the seawater samples was good.     

氢化物发生(HG)-ICP-AES测定中药漏芦中微量砷、锑、铋的研究

提出氢化物发生等离子体原子发射光谱（ＨＥ－ＩＣＰ－ＡＥＳ）值接测定中药漏芦中微量Ａｓ、Ｓｂ、Ｂｉ的方法。对影响分析信号的主要工作条件进行了选择和优化,对干扰元素及消除方法进行了考察。方法的检出限Ａｓ、Ｓｂ、Ｂｉ分别为２．７、３．４、２．８ｎｇ／ｇ,精密度（ＲＳＤ）为２．１％～５．０％,试样加入平均回收率为９２．５％～１０６．５％,本法用于中药漏芦的分析,结果满意。     

Determination of As, Sb, Bi and Hg in water samples by flow-injection inductively coupled plasma mass spectrometry with an in-situ nebulizer/hydride generator

A simple and very inexpensive in-situ nebulizer/hydride generator was used with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of As, Sb, Bi and Hg in water samples. The application of hydride generation ICP-MS alleviated the sensitivity problem of As, Sb, Bi and Hg determinations encountered when the conventional pneumatic nebulizer was used for sample introduction. The sample was introduced by flow injection to minimize the deposition of solids on the sampling orifice. The elements in the sample were reduced to the lower oxidation states with L-cysteine before being injected into the hydride generation system. This method has a detection limit of 0.003, 0.003, 0.017 and 0.17 ng ml⁻¹ for As, Bi, Sb and Hg, respectively. This method was applied to determine As, Sb, Bi and Hg in a CASS-3 nearshore seawater reference sample, a SLRS-2 riverine water reference sample and a tap water collected from National Sun Yat-Sen University. The concentrations of the elements were determined by standard addition method. The precision was better than 20% for most of the determinations.     

Separation and Removal of Mercury(II) from Water Samples Using (Acetylacetone)‐2‐Thiol‐Phenyleneimine Immobilized on Anion‐Exchange Resin Prior to Determination by Cold Vapor Inductively Coupled Plasma Atomic Emission Spectroscopy

Abstract

(Acetylacetone)‐2‐thiol‐phenyleneimine (H₂L) immobilized on an anion‐exchange resin (Dowex) was used for separation and removal of mercury from natural water samples and for preconcentration prior to its determination by cold vapor inductively coupled plasma atomic emission spectroscopy. The metal was eluted from the column using a solution of 10% thiourea in 0.1 M HCl. The modified resin is higly selective with an exchange capacity of 1.60 mmol g^?1. Various parameters like pH, column flow rate, and desorbing agents are optimized. The proposed method has a linear calibration range of 15–1000 ng/ml Hg(II), with a relative standard deviation at the 15 ng/ml level of 3.5%. The precision of the method (evaluated as the relative standard deviation obtained after analyzing six series of five replicates) was ±4.2% at the 50 ng/ml level of Hg(II). The method has been used for routine determination of trace levels of mercury species in natural waters. The potential application of modified resin for the removal of mercury(II) from two natural water samples (top water and lake water) spiked with 50 ng/ml of mercury (II) was studied by ICP‐AES, and the results proved that excellent percent extraction of mercury(II) from both natural water samples was obtained by column method using modified resin.     

Determination of arsenic and antimony in milk by hydride generation atomic fluorescence spectrometry

A highly sensitive procedure has been developed for total arsenic and antimony determination in milk samples by hydride generation atomic fluorescence spectrometry after microwave-assisted sample digestion. The discrete introduction of 2 ml of digested sample in the automated continuous flow hydride generation system allows us to reduce drastically the sample and HCl consume and to determine several elements from a same sample digestion. The method provides detection limits of 0.006 and 0.003 ng ml⁻¹, a sensitivity of 2390 and 2840 fluorescence units per ng ml⁻¹ for As and Sb respectively, and average relative standard deviation of 2.3% for As and 4.8% for Sb. The analysis of cow milk samples, obtained from the Spanish market evidenced the presence of As at concentration levels from 3.4 to 11.6 ng g⁻¹ and Sb levels from 3.5 to 11.9 ng g⁻¹, thus in a proportion near to 1:1, which is in contrast with the 10:1 natural ratio between As and Sb and could evidence the effect of the introduction of new alloys and polymer materials in the industrial process of milk. The method was validated by the comparison of data found for commercial samples by using the proposed procedure and reference methods based on dry-ashing and AFS, and microwave-assisted digestion and inductively coupled plasma mass spectrometry determination.     

Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge,As, Cd,Sb, Hg and Bi in cosmetic lotions

A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v l-cysteine, 0.5 μg mL⁻¹ Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng  g⁻¹ for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.     

Determination of Ce,Pr, Nd and Sm in High Purity La2O3 by Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

High purity lanthanum oxide was analysed to determine traces of Ce, Pr, Nd, and Sm by employing inductively coupled plasma atomic emission spectrometry (ICP-AES). Lanthanum oxide was dissolved in nitric acid and the solution was nebulized into the plasma generated by a RF generator (56 MHz; 1.5kW). Analytical lines of Ce, Pr, Nd, and Sm, which were free of interference from the spectral lines of both La and the other rare earths, were scanned on a Jobin-Yvon, Model JY-38 THR-1000 1m-Czerny-Turner monochromator. Standards containing the four analytes (Ce, Pr, Nd, and Sm) in the concentration range 0.01–0.2 μg/ml and La at 2 mg/ml were used for calibration. Detection limits ranged between 6 and 16 ng/ml for the four analytes in aqueous solution.     

Optimization of a single-drop microextraction method for multielemental determination by electrothermal vaporization inductively coupled plasma mass spectrometry following in situ vapor generation

A headspace single-drop microextraction (HS-SDME) method has been developed in combination with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the simultaneous determination of As, Sb, Bi, Pb, Sn and Hg in aqueous solutions. Vapor generation is carried out in a 40 mL volume closed-vial containing a solution with the target analytes in hydrochloric acid and potassium ferricyanide medium. Hydrides (As, Sb, Bi, Pb, Sn) and Hg vapor are trapped onto an aqueous single drop (3 µL volume) containing Pd(II), followed by the subsequent injection in the ETV. Experimental variables such as medium composition, sodium tetrahydroborate (III) volume and concentration, stirring rate, extraction time, sample volume, ascorbic acid concentration and palladium amount in the drop were fully optimized. The limits of detection (LOD) (3σ criterion) of the proposed method for As, Sb, Bi, Pb, Sn and Hg were 0.2, 0.04, 0.01, 0.07, 0.09 and 0.8 µg/L, respectively. Enrichment factors of 9, 85, 138, 130, 37 and 72 for As, Sb, Bi, Pb, Sn and Hg, respectively, were achieved in 210 s. The relative standard deviations (N = 5) ranged from 4 to 8%. The proposed HS-SDME-ETV-ICP-MS method has been applied for the determination of As, Sb, Bi, Pb, Sn and Hg in NWRI TM-28.3 certified reference material.     

Simultaneous Determination of Cadmium,Mercury, Lead,Arsenic, Copper,and Zinc in Human Breast Milk by ICP‐MS/Microwave Digestion

Abstract

An analytical method using microwave digestion and inductively coupled argon plasma-mass spectrometry (ICP‐MS) analysis was developed for the measurement of Cd, Hg, Pb, As, Cu, and Zn in human breast milk. We applied external calibration, internal calibration, and standard addition for reference material and pooled milk analysis. Method performances were defined in terms of detection limits, accuracy, and precision. Accuracy varied between 93% and 105% and precision between 3% and 8%. External calibration and background interferences were checked through a calibrator addition procedure. Our method has shown high accuracy, precision, and sensitivity, as well as linearity within a wide range of values. Our methodology, developed by treatment of reference material and pooled milk samples, was applied for determination of Cu, Zn, As, Cd, Hg, and Pb in 120 human breast milk samples.     

Flow injection electrochemical hydride generation inductively coupled plasma time-of-flight mass spectrometry for the simultaneous determination of hydride forming elements and its application to the analysis of fresh water samples

A flow injection (FI) method was developed using electrochemical hydride generation (EcHG) as a sample introduction system, coupled to an inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) for rapid and simultaneous determination of six elements forming hydrides (As, Bi, Ge, Hg, Sb and Se). A novel low volume electrolysis cell, especially suited for FI experiments was designed and the conditions for simultaneous electrochemical hydride generation (EcHG; electrolyte concentrations and flow rates, electrolysis voltage and current) as well as the ICP-TOFMS operational parameters (carrier gas flow rate, modulation pulse width (MPW)) for the simultaneous determination of 12 isotopes were optimized. The compromise operation parameters of the electrolysis were found to be 1.4 and 3 ml min⁻¹ for the anolyte and catholyte flow rates, respectively, using 2 M sulphuric acid. An optimum electrolysis current of 0.7 A (16 V) and an argon carrier gas flow rate of 0.91 l min⁻¹ were chosen. A modulation pulse width of 5 μs, which influences the sensitivity through the amount of ions being collected by the MS per single analytical cycle, provided optimum results for the detection of transient signals. The achieved detection limits were compared with those obtained by using FI in combination with conventional nebulization (FI-ICP-TOFMS); values for chemical hydride generation (FI-CHG-ICP-TOFMS) were taken from the literature. By using a 200 μl sample loop absolute detection limits (3σ) in the range of 10-160 pg for As, Bi, Ge, Hg, Sb and 1.1 ng for Se and a precision of 4-8% for seven replicate injections of 20-100 ng ml⁻¹ multielemental sample solutions were achieved. The analysis of a standard reference material (SRM) 1643d (NIST, “Trace Elements in Water”) showed good agreement with the certified values for As and Sb. Se showed a drastic difference, which is probably due to the presence of hydride-inactive Se species in the sample. Recoveries better than 93% for Ge and Hg and 83.9% for Se were achieved on a spiked SRM sample. The developed method was successfully applied to the simultaneous multielemental determination of hydride forming elements in spring water samples originating from two different regions in Hungary.     

Dual nebulizer sample introduction system for simultaneous determination of volatile elemental hydrides and other elements

A dual sample introduction system was explored for volatile hydride generation in inductively coupled plasma–optical emission spectrometry (ICP–OES) performed in the radially viewed mode. The system consists of two pneumatic nebulizers connected to the conventional spray chamber of the instrument via a simple adaptor. This configuration permits hydride generation but still allows other elements to be determined by pneumatic nebulization. This work was focused on the optimization of the plasma operating conditions for the determination of As, Hg, Sb and Se and other elements. The excitation conditions of the ICP–OES instrument operated with the dual sample introduction system were also explored. Results showed that the analytical performance of the dual system for the determination of As, Hg, Sb and Se was superior to those of conventional nebulization systems. The dual system also enabled the determination of elements that do not form volatile hydrides, but with less sensitivity than conventional nebulization systems. An evaluation of the plasma robustness showed that the gases generated in the hydride reactions did not significantly affect the plasma discharge. Similar to conventional hydride generation techniques, the analysis was susceptible to nonspectroscopic interferences produced by transition metals. Finally, the applicability of the dual nebulization system to practical ICP–OES studies was demonstrated by determining the trace elements in an oyster tissue standard reference material.      

化学蒸汽发生/电感耦合等离子体质谱法测定近岸及河口海水中的超痕量砷、锑、铋、锗、锡、汞

建立了化学蒸汽发生(CVG)电感耦合等离子体质谱(ICP MS)同时测定近岸及河口海水中超痕量As、Sb、Bi、Ge、Sn和Hg元素的方法.研究了CVG过程中KBH4、盐酸和硫脲的浓度以及样品流速、载气流速、海水样品盐度等对方法分析性能的影响.结果表明,在0.70％6盐酸、0.10 g/L硫脲、11.0 g/L硼氧化钾...     

Determination of As, Ge, Hg, Pb, Sb, Se and Sn in coal slurries by CVG-ETV-ICP-MS using external or isotopic dilution calibration

A method for the multi-elemental determination of As, Ge, Hg, Pb, Sb, Se and Sn in coal reference materials by slurry sampling chemical vapor generation (CVG) using external calibration and isotopic dilution (ID) calibration and detection by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) is proposed. As, Ge, Sb, Se and Sn were determined using the external calibration, while, Hg, Pb, Se and Sn were determined by isotopic dilution. About 50–250 mg of sample was mixed with an acid solution, containing aqua regia and HCl, in an ultrasonic bath. For the isotopic dilution calibration, the enriched isotopes ²⁰¹Hg, ²⁰⁶Pb, ⁷⁷Se and ¹¹⁹Sn were added to the slurry in an adequate amount in order to produce an altered isotopic ratio close to 1. The vapor produced by the reaction of the sample slurry with the reducing agent was transported to the vaporizer and trapped in a Ir-treated graphite tube at 200 °C, before vaporization at 2100 °C and transportation of the vapor to the plasma. The accuracy of the method was assured by the analysis of four certified reference coal samples, using external calibration with aqueous solutions, prepared in the same medium and subjected to the same CVG and trapping procedure as the slurries and also by isotopic dilution calibration. The obtained concentrations were in agreement with the certified values, using the t-Student test for a confidence level of 95%. The detection limits (3 s; n = 5) of isotopic dilution, in ng g^− 1, were: 0.4 for Hg, 900 for Pb, 0.3 for Se and 0.2 for Sn. For external calibration, the detection limits, in ng g^− 1, were: 1.6 for As, 0.1 for Ge, 0.3 for Sb, 0.9 for Se and 7.5 for Sn. The relative standard deviations generally were lower than 14%, adequate for slurry analysis.     

Speciation of Antimony(III) and Antimony(V) in Bottled Water by Hydride Generation-Inductively Coupled Plasma Optical Emission Spectrometry

Speciation of Sb(III) and Sb(V) was investigated using hydride generation with the selective formation of stibine from Sb(III). A continuous flow system using a homemade gas-liquid separator with inductively coupled plasma optical emission spectrometry was employed. The conditions and concentrations of NaBH₄, HCl, citric acid, and KI were optimized to obtain limits of detection of 0.05 for Sb(III) and 0.11 µg L^?1 for total Sb without preconcentration. An attractive sampling rate of 26 analyses h^?1 was obtained, suggesting application for routine analysis. The method was employed for the determination of Sb(III) and total Sb in bottled drinking water, and recovery values between 82.0 and 98.8% with relative standard deviation lower than 6.2% were observed, demonstrating appropriate accuracy and precision.     

A Hydride Generation-Ultrasonic Nebulization System for Plasma Spectrometries

Both hydride generation (HG) techniques and ultrasonic nebulizers (USN) have been extensively applied for the determination of trace elements by inductively coupled plasma (ICP) atomic emission spectrometry or by ICP mass spectrometry. HG is actually a preconcentration system, which has good power of detection and high sensitivity for As,Se, Sb, Bi, Te,Hg, Pb, and Sn.     

Determination of hydride forming elements (As,Sb, Se,Sn) and Hg in environmental reference materials as acid slurries by on-line hydride generation inductively coupled plasma mass spectrometry

A method for the determination of As, Hg, Sb, Se and Sn in environmental and in geological reference materials, as acidified slurries, by flow injection (FI) coupled to a hydride generation system (HG) and detection by inductively coupled plasma mass spectrometry (ICP-MS) is proposed. The HG unit has a gas liquid separator and a drying unit for the generated vapor. The slurries were prepared by two procedures. Approximately 50 mg of the reference material, ground to a particle size ≤50 μm, was mixed with acid solutions in an ultrasonic bath. In Procedure A, the medium was a hydrochloric acid solution while in Procedure B, the medium was aqua regia plus a hydrochloric acid solution. The conditions for the slurry formation and the instrumental parameters were optimized. Harsh conditions were used in the slurry preparation in order to reduce the hydride forming analytes to their lower oxidation states, As (III), Se(IV), Sb(III) and Sn(II), before reacting with sodium tetrahydroborate. To test the accuracy, 10 certified reference materials were analyzed (four sediments, three coals, one coal fly ash and two sewage sludges), with the analyte concentrations mostly in the μg g⁻¹ level. Good agreements with the certified values were obtained for Hg, Sb and Sn in the sediments using Procedure A and calibration against aqueous standard solutions. Using Procedure B, good results were obtained for Hg, Se and Sn in the sediment samples, for Se in the coal and coal fly ash samples and for Hg in the sewage sludge samples, also using external calibration with aqueous standard solutions. For As in sediments, coals and coal fly ash, Procedure B and the analyte addition calibration was required, indicating matrix effects. The relative standard deviations were lower than 5%, demonstrating a good precision for slurry analysis. The limits of quantification (10 times the standard deviation; n=10), in the samples, in ng g⁻¹, were: 20 for As, 60 for Hg, 80 for Sb, 200 for Se and 90 for Sn. The method requires small amounts of reagents and reduces contamination and losses.     

Simultaneous determination of hydride forming elements (As, Sb, Se, Sn) and Hg in sonicate slurries of biological and environmental reference materials by hydride generation microwave induced plasma optical emission spectrometry (SS-HG-MIP-OES)

A slurry sampling hydride generation (SS-HG) method for the simultaneous determination of hydride forming elements (As, Sb, Se, Sn) and Hg, without total sample digestion, has been developed using batch mode generation system coupled with microwave induced plasma optical emission spectrometry (MIP-OES) from certified biological and environmental reference materials. Slurry concentration up to 3.6% m/v (particles < 80 μm) prepared in 10% HCl containing 100 μl of decanol, by the application of ultrasonic agitation, was used with calibration by the standard addition technique. Harsh conditions were used in the slurry preparation in order to reduce the hydride forming elements to their lower oxidation states, As(III), Sb(III), Se(IV) and Sn(II) and Hg, being reduced to mercury vapor, before reacting with sodium tetrahydroborate. An ultrasonic probe was used to homogenize the slurry in the quartz cup just before its introduction into the reaction vessel. For 10 ml of slurry sample, detection limits (LOD, 3σ_blank, peak area) of 0.06, 0.08, 0.15, 0.12 and 0.10 μg g^− 1 were obtained for As, Sb, Se, Sn and Hg, respectively. The method offers relatively good precision (RSD ranged from 9 to 12%) for slurry analysis. To test the accuracy, three certified reference materials were analyzed with the analyte concentrations mostly in the μg g^− 1 level. Measured concentrations are in satisfactory agreement with certified values for the biological reference materials: NRCC LUTS-1 (lobster hepatopancreas), NRCC DOLT-2 (Dogfish Liver) and environmental reference material: NRCC PACS-1 (Marine Sediment), all adequate for slurry sampling. The method requires small amounts of reagents and reduces contamination and losses.     

The use of optical emission spectrometry with microwave induced plasma (MIP) discharges in a surfatron combined to different types of hydride generation for the determination of arsenic

The stability and analytical figures of merit of argon microwave induced plasma (MIP) discharges in a surfatron as sources for optical emission spectrometry (OES) are described. These MIPs have been used for the determination of arsenic after hydride generation. They could cope with the excess of hydrogen developed during the hydride generation step and thus not necessitated an isolation of the hydrides before releasing them into the MIP. Two methods for the generation of the volatile AsH₃ were applied. First a micro method was used with solid NaBH₄ on which 10 1 of the acidified sample solution is transferred. Its capabilities were compared to those of continuous hydride generation using a 5% (w/w) NaBH₄-solution and continuous liquid removal in a flow cell. Both methods were optimized for an argon MIP operated at a power of 120–160 W and gas flows of 20 l/h Ar. In the case of solid NaBH₄ the detection limit for As has been found to be 1.0 g/ml (10 ng) and with the flow cell hydride generation 50 ng/ml. The calibration curves are linear over three orders of magnitude. Interferences caused by Sb, Fe, Sn and NaCl were investigated. No interferences occurred for Sb up to an interferent concentration of 250 g/ml. The presence of Fe causes a significant depression of the As signal whereas an increase of the As signal was observed in the case of Sn. High NaCl concentrations did not influence the As signals when using continuous hydride generation, but had a great influence when using solid NaBH₄.     

Behaviour of the dithiocarbamate complexes of arsenic, antimony, bismuth, mercury, lead, tin and selenium in methanol with a hydride generator

A study was carried out with a continuous hydride generator coupled to an atomic emission spectrometer with inductively-coupled plasma to determine whether hydrides of As, Bi, Pb, Sb, Sn and Se and mercury vapor could be generated in methanol solutions of their dithiocarbamate complexes. It was found that (with the exception of Pb) hydride generation with sufficient efficiency for simultaneous multi-element determination is achieved using 0.25% NaBH(4)-0.6 mol 1(-1) HCl as reaction medium. The detection limit was found to be 0.2 ng ml(-1) for As, 30 ng ml(-1) for Bi, 0.03 ng ml(-1) for Se, Sb and Sn.     

Tandem on-line continuous separations for atomic spectroscopic indirect analysis: Iodide determination by ICP-AES

A sensitive and selective indirect determination of iodide by inductively coupled plasma emission spectrometry (ICP-AES) based on the principle of tandem on-line continuous separations as an alternative means of introducing samples into plasmas is proposed. Iodide is continuously extracted as an ion-pair into xylene by mixing the sample with Hg(II) and dipyridil solutions. The organic phase (containing the analyte in [Hg(Dipy)₂]I₂ form) is on-line continuously mixed with NaBH₄ (in DMF) and acetic acid solutions. Mercury vapour continuously generated from this organic phase is separated in a classical U-type gas-liquid separation device. The system has been optimized for the continuous extraction of KI, for the direct generation of cold mercury vapour from xylene and for the final ICP-AES determination of mercury. The optimised method has been applied to the determination of iodide (detection limit 20 ng/ml of iodide) in table salt and in synthetic samples. Very good agreement between found and certified results was observed. The usefulness and convenience of such alternative sample chemical pretreatment/presentation to the ICP is thus demonstrated for indirect determinations to be carried out by atomic spectroscopy methods.