Determination of lead in household refuse fly-ash by X-ray fluorescence spectrometry and a modified standard-addition technique

Lead in fly-ash from a garbage incinerator has been determined by X-ray fluorescence spectrometry (XRFS) and a modified standard-addition method. To keep the attenuation properties of the spiked samples constant, decreasing amounts of an attenuation modifier [mercury (II) acetate] were added together with increasing amounts of the standard (lead nitrate). Linearity between fluorescence intensity and amount of lead was thus obtained, so the amount of lead in the sample could be evaluated by linear regression. The amount of modifier needed could be calculated from a simple expression. The method was validated by comparison with the results obtained by applying atomic-absorption spectrometry (AAS) to solutions made by leaching the fly-ash with strong acid. For 8 fly-ash samples, containing between 0.8 and 1.35% lead, the largest absolute difference between the two sets of results was 0.03%. Theoretical calculations based on a simplified version of the Sherman equation were performed to confirm the linearity of the modified standard-addition curves.     

Atomic absorption spectrometric determination of ultra trace amounts of zinc after preconcentration with the ion pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and ammonium tetraphenylborate on microcrystalline naphthalene or by column method

Zinc is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylamminophenol (5-BrPADAP)-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 7.5-9.0 from a large volume of aqueous solutions of various samples. After filtration, the solid mass consisting of the zinc complex and naphthalene was dissolved with 5 ml of dimethylflarmamide and the metal was determined by atomic absorption spectrometry. Zinc complex can alternatively be quantitatively adsorbed on ammonium tetrphenylborate-naphthalene adsorbent packed in a column and determined similarly. The calibration curve is linear 0.05-4.0 ppb in dimethylformamide solution. Eight replicate detenninations of 1.0 ppb of zinc gave a mean absorbance of 0.124 with a relative standard deviation of 1.3%. The sensitivity for 1% absorption was 0.035 ppb. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the trace determination of zinc in various standard samples.     

Determination of zinc in marine/lacustrine sediments by graphite furnace atomic absorption spectrometry using Pd/Mg chemical modifier and slurry sampling

Effectiveness of Pd/Mg chemical modifier for the accurate direct determination of zinc in marine/lacustrine sediments by graphite furnace atomic absorption spectrometry (GF-AAS) using slurry samples was evaluated. A calibration curve prepared by aqueous zinc standard solution with addition of Pd/Mg chemical modifier is used to determine the zinc concentration in the sediment. The accuracy of the proposed method was confirmed using Certified Reference Materials, NMIJ CRM 7303-a (lacustrine sediment) from National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Japan, and MESS-3 (marine sediment) and PACS-2 (marine sediment) from National Research Council, Canada. The analytical results obtained by employing Pd/Mg modifier are in good agreement with the certified values of all the reference sediment materials. Although for NRC MESS-3 an accurate determination of zinc is achieved even without the chemical modifier, the use of Pd/Mg chemical modifier is recommended as it leads to establishment of a reliable and accurate direct analytical method. One quantitative analysis takes less than 15 minutes after we obtain dried sediment samples, which is several tens of times faster than conventional analytical methods using acid digested sample solutions. The detection limits are 0.13?µg?g^?1 (213.9?nm) and 16?µg?g^?1 (307.6?nm), respectively, in sediment samples, when 40?mg of dried powdered samples are suspended in 20?mL of 0.1?mol?L^?1 nitric acid and a 10?µl portion of the slurry sample is measured. The precision of the proposed method is 8–15% (RSD).     

Determination of Mercury and Thallium in Seawater by Electrothermal Vaporization Inductively Coupled Plasma Mass Spectrometry

Electrothermal vaporization inductively coupled plasma mass spectrometry (ETV‐ICP‐MS) has been applied to the determination of Hg and Tl in seawater samples. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.3% EDTA, 0.1%m/vTAC and 1% v/v HCl were added to the sample solution to work as the modifier. Since the sensitivities of Hg and Tl in various seawater matrices and aqueous standard solutions were quite different, standard addition method and isotope dilution method were used for the determination of Hg and Tl in these seawater samples. This method was applied to the determination of Hg and Tl in NASS‐4 and CASS‐3 reference seawater samples and seawater samples collected from the Kaohsiung area. Results obtained by isotope dilution method and method of standard additions agreed satisfactorily. Detection limits were in the range of 5‐15 and 0.4‐0.5 ng l^?1 for Hg and Tl in seawater, respectively, with the ETV‐ICP‐MS method. The precision between sample replicates was better than 18%) for all the determinations.     

Atomic absorption spectrometric determination of trace zinc in alloys and biological samples after preconcentration with [1-(2-pyridylazo)-2-naphthol] on microcrystalline naphthalene

An atomic absorption spectrometric method for the determination of trace amounts of zinc after adsorption of its [1-(2-pyridylazo)-2-naphthol] complex on microcrystalline naphthalene has been developed. This complex is adsorbed on microcrystalline naphthalene in the pH range 3.5-7.5 from large volumes of aqueous solutions of various alloys and biological samples with a preconcentration factor of 40. After filtration, the solid mass consisting of the zinc complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Zinc can alternatively be quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. About 0.5 ng of zinc can be concentrated in a column from 200 ml of aqueous sample, where its concentration is as low as 2.5 pg ml-1. The calibration curve is linear in the range 0.1-6.5 ng ml-1 in dimethylformamide solution. Eight replicate determinations of 2 ng ml-1 of zinc gave a mean absorbance of 0.145 with a relative standard deviation of 1.5%. The sensitivity for 1% absorption was 0.061 ng ml-1. Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of zinc, have been studied in detail to optimize the conditions for the determination of zinc in various standard complex materials.     

Determination of indium by graphite furnace atomic absorption spectrometry after coprecipitation with chitosan.

A sensitive and simple method for the determination of trace amounts of indium in water samples by graphite furnace atomic absorption spectrometry (GFAAS) after coprecipitation with chitosan was investigated. Indium was quantitatively preconcentrated from water samples by coprecipitation with chitosan at pH 7.0-9.0. The coprecipitant was easily dissolved with acetic acid, and indium in the resulting solution was determined by GFAAS. The addition of lanthanum as a chemical modifier was more effective for the atomic absorbance of indium. The detection limit (S/N > or = 3) for indium was 0.04 microg dm(-3), and the relative standard deviations (n = 5) were 3.5-4.5% at 1.0 microg/100 cm3. The results obtained in this study indicate that the proposed method can be successfully applied to the determination of trace indium in water samples.     

Electrothermal atomic-emission spectrometric determination of lithium with a metal-tube atomizer and a matrix modifier

Electrothermal atomic-emission spectrometric determination of lithium with use of a tungsten tube has been investigated. Lanthanum nitrate is used as a matrix modifier to eliminate the interference of Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn. Lithium in biological samples has been determined by the method. The recovery of lithium in the samples was > 91%.     

Use of iridium plus rhodium as permanent modifier to determine As, Cd and Pb in acids and ethanol by electrothermal atomic absorption spectrometry

The most severe interferences in atomic absorption spectrometry are caused by the presence of anions when they are in different concentrations in the samples and in the calibration solutions. The analyte addition technique or matrix matching calibration can be employed to minimize or compensate the non-spectral interferences, but they are time consuming or difficult to be carried out. The use of chemical modifiers usually allows higher pyrolysis temperatures and consequently the removal of components of the sample matrix, equalizing the analyte signal in the sample and in the calibration solution. In this work, a mixture of Ir and Rh is proposed as permanent modifier to determine As, Cd and Pb in diluted hydrochloric, sulfuric and phosphoric acids and in ethanol and methanol by electrothermal atomic absorption spectrometry (ET AAS) with calibration against 1% v/v nitric acid aqueous solutions. The performance of the proposed permanent modifier was compared to that of Pd plus Mg nitrates in solution. Better recoveries, low background levels and faster analysis were obtained with the permanent modifier. The permanent modifier was also successfully employed for the determination of As, Cd and Pb in different concentrations of sulfuric and hydrochloric acids. For the phosphoric acid, the proposed modifier was only efficient for acid concentrations up to 2% v/v for As and up to 5% v/v for Cd and Pb. The precision, expressed as the relative standard deviation (n=3), was lower than 10%, for all samples, including ethanol and methanol.     

Selective determination of ultra trace amounts of gold by graphite furnace atomic absorption spectrometry after dispersive liquid-liquid microextraction

A simple, rapid and sensitive method is proposed for selective determination of ultra trace amounts of gold from different samples. The method is based on highly efficient separation and pre-concentration of gold by dispersive liquid-liquid microextraction of gold followed by its determination with graphite furnace atomic absorption spectrometry. The pre-concentration procedure results in quantitative extraction of gold by victoria blue R from a 10-mL sample into fine droplets of chlorobenzene, with a sedimented volume of 25 microL. Then, 20 microL of 0.04% Pd(NO3)2, as chemical modifier, followed by 10 microL of the sedimented phase were consecutively pipetted into the same auto-sampler device and the content is injected into the graphite tube and the gold content is determined by graphite furnace atomic absorption spectrometry. After optimizing the extraction conditions and instrumental parameters, a pre-concentration factor of about 388 is obtained for the system. The analytical curve is linear in a concentration range of 0.03-0.5 ng mL(-1). The detection limit and relative standard deviation are 0.005 ng mL(-1) and 4.2%, respectively. The method was successfully applied to the extraction and determination of gold in tap water and silicate ore samples.     

Standard addition method applied to the urinary quantification of nicotine in the presence of cotinine and anabasine using surface enhanced Raman spectroscopy and multivariate curve resolution

In this work, urinary nicotine was determined in the presence of the metabolite cotinine and the alkaloid anabasine using surface enhanced Raman spectroscopy and colloidal gold as substrate. Spectra were decomposed using the multivariate curve resolution-alternating least squares method, and pure contributions were recovered. The standard addition method was applied by spiking urine samples with known amounts of the analyte and relative responses from curve resolution were employed to build the analytical curves. The use of multivariate curve resolution in conjunction with standard addition method showed to be an effective strategy that minimized the need for reagent and time-consuming procedures. The determination of the alkaloid nicotine was successfully accomplished at concentrations 0.10, 0.20 and 0.30 μg mL⁻¹ and total error values less than 10% were obtained.     

Evaluation of Different Modifiers for the Determination of Arsenic in Leachate Samples from Sanitary Landfills by Electrothermal Atomic Absorption Spectrometry

The aim of the present work was to develop and validate a rapid and accurate method of arsenic determination in leachate samples by electrothermal atomic absorption spectrometry. Leachate samples from sanitary landfills are considered difficult samples to analyze due to severe matrix interferences. A comparative study of various chemical modifiers was performed: Pd, Mg, Au, Pt, Ru, Rh, Ir, C₆H₈O₇ (citric acid), Pd + Mg, Ir + Mg, and the permanent modifier Zr – Ir.

Among the modifiers tested, the mixture 5 µg Ir + 40 µg Mg provided the best performance, followed by the permanent modifier Zr – Ir (a coating of 200 µg Zr + 20 µg Ir). The permanent modifier was finally chosen due to the decreased background signal and sufficient sensitivity.

In order to investigate the presence of matrix interference and exploit the possibility of performing calibrations by simple aqueous solutions, calibration with aqueous standards, matrix matched standards and with standard additions was performed. It was observed that, in the presence of the Zr – Ir permanent modifier, the slopes of the calibration curve and the matrix-matched/standard addition curves were statistically different (checked by t-test). The recoveries from matrix-matched calibrations for three concentration levels were ranged between 96.4% and 100%. Precision experiments were also performed and the relative standard deviation (%RSD) for four different concentrations was ≤10%. The method was applied to the determination of arsenic in leachate samples collected in the solid waste sanitary landfill of Ano Liossia, Attika, Greece.     

Determination of lead in fish samples by slurry sampling electrothermal atomic absorption spectrometry

Ultrasonic slurry sampling electrothermal atomic absorption spectrometry (USS-ETAAS) was been applied to the determination of lead in several fish samples. The influences of instrument operating conditions and slurry preparation on the signal were examined. Palladium and ammonium nitrate were used as the modifier to improve the signal. Since the sensitivity to lead in various fish slurries and aqueous solutions was different, the standard additions method was used for the determination of lead in these fish samples. The method was applied to the determination of lead in dogfish muscle reference material (DORM-2) and a swordfish muscle sample purchased from the local market. The analysis results agreed with the reference value. The accuracy was better than 6%. The precision between sample replicates was better than 16% with the USS-ETAAS method. The detection limit of lead estimated from standard additions curve was about 0.053-0.058 microgram g-1 in different samples.     

Determination of Pd,Rh, Pt,Au in road dust by electrothermal vaporization inductively coupled plasma mass spectrometry with slurry sampling

Inductively coupled plasma mass spectrometry coupled with ultrasonic slurry sampling electrothermal vaporization (USS-ETV-ICP-MS) has been applied to determine Pd, Rh, Pt and Au in 0.5% m/v slurries of several road dust samples. 2% m/v ammonium pyrrolidine dithiocarbamate (APDC) was used as the modifier to enhance the ion count. The influence of instrument operating conditions, slurry preparation and interferences on the ion count was reported. This method has been applied to the determination of Pd, Rh, Pt and Au in BCR 723 Road Dust and NIST SRM 2709 San Joaquin Soil reference materials and two road dust samples collected locally. The analysis results of the standard reference materials agreed with the certified values. Precision between sample replicates was better than 10% for all the determinations. The method detection limits estimated from standard addition curves were 0.9, 0.4, 0.6 and 0.4 ng g⁻¹ for Pd, Rh, Pt and Au, respectively, in original dust samples.     

石墨炉原子吸收光谱法测定压水反应堆硼酸介质中钙

以甘露醇为基体改进剂,建立石墨炉原子吸收光谱法测定压水反应堆硼酸介质中钙含量的方法。考察基体改进剂用量、灰化温度、原子化温度、基体干扰以及共存离子干扰对测定结果的影响,确定最佳测定条件:以硼含量为1000 mg/kg的硼酸为背景基体,加入适量甘露醇,样品作酸化处理,灰化温度为1700℃,原子化温度为2450℃。钙含量在8~32 μg/kg范围内与光谱强度成良好的线性关系,相关系数为0.9996,方法检出限为1.79 μg/kg。对于硼基体含量为0~2500 mg/kg的样品,测定结果的相对标准偏差为0.5%~7.5%(n=6),相对误差不大于13.2%,加标回收率为93.9%~113.3%。该方法检测速度快,结果准确,能满足实际生产要求。     

Direct FIA-AS determination of potassium and magnesium in cement samples by use of the slurries approach

A direct procedure has been developed for the flame atomic determination of potassium and magnesium in cement samples. A 50-mg sample is dispersed in 25 ml of 0.13M nitric acid; 100 mul of this slurry is injected in a double channel FIA manifold simultaneously with 100 mul of a 10% (w/v) lanthanum solution. This procedure allows the rapid extraction of potassium and magnesium by leaching of the sample; nitric acid is not necessary if only potassium must be determined and the sample can be diluted with only distilled water. Aqueous standards are used. The manifold employed includes a well-stirred mixing chamber, which provides an adequate on-line dilution of the sample, in order to obtain emission or absorbance measurements in the dynamic range of the elements to be determined. The results obtained in the analysis of real samples agree with those found by flame atomic spectrometry after a previous alkaline fusion with lithium carbonate, and exhibit better precision. The limit of detection of the procedure is 0.007% for K(2)O and 0.01% for MgO and the precision of the entire procedure corresponds to a relative standard deviation of 1%.     

便携式X射线荧光光谱法同时测定氧化锌富集物中锌铁氯镉砷

氧化锌富集物的进口能弥补我国锌矿资源的不足,但要求ZnO>50%、Fe<10%、Cl<8%、Cd<0.25%、As<0.6%。目前常采用YS/T 1171.1～10-2017《再生锌原料化学分析方法》检测氧化锌富集物中锌铁氯镉砷含量,该系列检测方法均需要繁琐的湿法样品前处理,测量过程较为冗长,不能满足氧化锌富集物大量进口时快速通关的需求。故实验建立了采用便携式X射线荧光光谱法(PXRF)同时测定氧化锌富集物中锌铁氯镉砷的方法。采用YS/T 1171.3-2017和YS/T 1171.5-2017方法对氧化锌富集物样品进行定值,然后选取21个含量具有梯度的氧化锌富集物样品作为校准样品,建立起各元素X射线荧光强度值与含量的校准曲线。各曲线相关系数在0.8164～0.9999,方法检出限为0.013%～1.95%,各元素的相对标准偏差(RSD,n=11)均小于0.05%。采用本方法和化学方法分别检测氧化锌富集物样品,各元素的本方法检测值与化学分析方法检测值的相对误差均小于20%。本方法能应用到口岸现场进口氧化锌富集物快速筛查,检测一个样品仅需1分钟测量时间,极大地加快了进口氧化锌富集物通关速度。     

Reduction of matrix effects and improvement of sensitivity during determination of two chloridazon degradation products in aqueous matrices by using UPLC-ESI-MS/MS

The development and validation of a sensitive and reliable detection method for the determination of two polar degradation products, desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) in surface water, ground water and drinking water is presented. The method is based on direct large volume injection ultra-performance liquid chromatography electrospray tandem mass spectrometry. This simple but powerful analytical method for polar substances in the aquatic environment is usually hampered by varying matrix effects, depending on the nature of different water bodies. For the two examined degradation products, the matrix effects are particularly strong compared with other polar degradation products of pesticides. Therefore, matrix effects were studied thoroughly with the aim of minimising them and improving sensitivity during determination by postcolumn addition of ammonia solution as a modifier. An internal standard was used in order to compensate for remaining matrix effects. The calibration curve shows very good coefficients of correlation (0.9994 for DPC and 0.9999 for MDPC). Intraday precision values were lower than 5 % for DPC, 3 % for MDPC and the limits of detection were 10 ng/L for both substances. The method was successfully used in a national round robin test with a deviation between 3 and 8 % from target values. Finally, about 1,000 samples from different water bodies have been examined with this method in the Rhine and Ruhr region of North-Rhine-Westphalia (Germany) and in the European Union. Approximately 76 % of analysed samples contained measurable amounts of DPC at concentrations up to 8 μg/L while 53 % of the samples showed MDPC concentrations up to 2.3 μg/L.     

原子荧光光谱法测定粗锌中的砷

建立了测定粗锌中砷含量的原子荧光光谱法。粗锌样品经硝酸溶液(1+1)低温溶解完全以后,在盐酸介质中,用抗坏血酸预还原,以硫脲掩蔽铜、铁、银等杂质元素,砷被硼氢化钾还原为氢化物,用氩气导入原子化器测量。砷测定结果的相对标准偏差为1.5%~3.0%(n=11),加标回收率为98.4%~103.6%。与国家标准测定方法分光光度法测定结果对比,相对偏差为0.1%~2.4%。该法准确、可靠,适用于砷含量在0.005 0%~0.50%之间的粗锌中砷的测定。     

Simultaneous micellar liquid chromatographic analysis of seven water-soluble vitamins: optimization using super-modified simplex

A super-modified simplex (SMS) method has been used to optimize the mobile phase used for separation of seven water-soluble vitamins in multivitamin tablets by gradient micellar liquid chromatography (MLC) with ultraviolet (UV) detection at 254, 295, and 361 nm. Effect of column temperature and addition of organic modifier to the mobile phase on separation efficiency were investigated: the appropriate conditions used were a temperature of 35 degrees C and 1-butanol modifier. The sodium dodecyl sulfate (SDS) concentration, pH, and 1-butanol% in the mobile phase were chosen for simultaneous optimization using the SMS method. The optimum mobile phase was found to be 16 mmol L(-1) (mM) SDS, 0.02 M phosphate buffer, pH 3.6, and a gradient of 3.5-10% (v/v) butanol. The total analysis time for vitamins was 75 min. The analytical parameters including linearity ( r>0.9970), limit of detection (0.12-50 micro g mL(-1)), precision of method (relative standard deviation (RSD) <8.90%), and accuracy obtained by the recovery assay (88-103%) support the usefulness of the proposed method for the determination of the water-soluble vitamins.     

Determination of cadmium,mercury and lead in seawater by electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry

Electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (ETV-ID-ICP-MS) has been applied to the determination of Cd, Hg and Pb in seawater samples. The isotope ratios of the elements studied in each analytical run were calculated from the peak areas of each isotope. Various modifiers were tested for the best signal of these elements. After preliminary studies, 0.15% m/v TAC and 4% v/v HCl were added to the sample solution to work as the modifier. The ETV-ID-ICP-MS method has been applied to the determination of Cd, Hg and Pb in NASS-4 and CASS-3 reference seawater samples and seawater samples collected from Kaohsiung area. The results for reference sample NASS-4 and CASS-3 agreed satisfactorily with the reference values. Results for other samples determined by isotope dilution and method of standard additions agreed satisfactorily. Detection limits were approximately 0.002, 0.005 and 0.001 ng ml⁻¹ for Cd, Hg and Pb in seawater, respectively, with the ETV-ICP-MS method. Precision between sample replicates was better than 20% for most of the determinations.