直接进样钨丝电热蒸发-原子荧光光谱法快速测定蒸馏酒中镉

为了快速低成本测定蒸馏酒中痕量重金属镉,利用钨丝电热蒸发器作为直接进样装置,与原子荧光光谱仪原子化器直接连接,构建了用于蒸馏酒中镉测定的直接进样原子荧光光谱检测系统(W-coil ETV-AFS),并对工作气体的气氛和流速、灰化和蒸发电压、样品承载量等参数进行了优化,建立了蒸馏酒中镉的直接进样快速检测方法.在最优条件下...     

电热蒸发钨丝在线捕获原子荧光光谱法直接测定菠菜中痕量镉

利用钨丝(TC)常温下特异性捕获镉(Cd)消除基体干扰,泡沫碳材料电热蒸发器串联原子荧光光谱仪,实现了固体直接进样测定菠菜鲜样中痕量Cd。研究表明,泡沫碳电热蒸发器性能稳定,样品个体差异对测定无影响;经液氮冷冻粉碎的菠菜鲜样均匀度良好,Pauwels公式估算最小取样量为16.3 mg,满足仪器微量进样要求。采用灰化(50 W保持50 s,70 W保持80 s)、蒸发(70 W保持30 s)过程分离,Ar-H2(9∶1,V/V)载气流速为600 mL/min时,方法检出限可达0.2μg/kg,回收率为90.1%~106.1%,RSD小于10%,分析时间少于5 min,常见金属元素和有机物质对测定无干扰,且与微波消解石墨炉原子吸收光谱法结果无显著性差异(p>0.05)。     

电热蒸发-直接进样-冷原子吸收光谱法测定土壤以及沉积物中汞

采用传统分析仪器测定汞元素,需要对样品进行化学消解,存在操作繁杂、效率低以及易交叉污染等问题。故建立了电热蒸发-直接进样-HGA-100测汞仪测定土壤以及沉积物中汞的方法,无需对样品进行化学前处理,降低环境污染。通过优化HGA-100测汞仪参数条件,汞质量浓度在0~20ng以及20~200ng,相关系数优于0.998,准确称量样品0.05g(精确至0.000 1g),方法检出限为0.5μg/kg,相对标准偏差1.6%~4.6%,加标回收率在90.1%~100%。方法用于对土壤和沉积物标准物质测定,结果与标准值相符。方法高效、准确,可用于测定土壤以及沉积物中的汞。     

电热蒸发-直接进样-冷原子吸收光谱法测定土壤以及沉积物中汞

采用传统分析仪器测定汞元素,需要对样品进行化学消解,存在操作繁杂、效率低以及易交叉污染等问题。故建立了电热蒸发-直接进样-HGA-100测汞仪测定土壤以及沉积物中汞的方法,无需对样品进行化学前处理,降低环境污染。通过优化HGA-100测汞仪参数条件,汞质量浓度在0~20ng以及20~200ng,相关系数优于0.998,准确称量样品0.05g(精确至0.000 1g),方法检出限为0.5μg/kg,相对标准偏差1.6%~4.6%,加标回收率在90.1%~100%。方法用于对土壤和沉积物标准物质测定,结果与标准值相符。方法高效、准确,可用于测定土壤以及沉积物中的汞。     

原子荧光光谱法测定食品中的镉

研究了在水溶液中，Ｃｄ与ＫＢＨ４反应生成挥发性物种，以原子荧光光谱法测定食品中的痕量Ｃｄ的分析方法，方法的检出限为０．１２μｇ／Ｌ，线性范围０～５０μｇ／Ｌ，回收率为８６％～１１２％。     

氢化物发生原子荧光光谱法测定头发中的镉

采用氢化物发生原子荧光光谱法测定了头发中微量镉。样品用硝酸-高氯酸消化,用30 g/L的硼氢化钾作还原剂,在0.11 mol/L的硫酸介质中测定,方法的检出限为0.08 ng/mL,方法的精密度为1.21%,回收率为96%~110%。     

抗坏血酸-磺胺增效氢化物发生-原子荧光光谱法测定土壤中镉

建立了一种用抗坏血酸-磺胺双络合体系进行氢化物原子荧光光谱法测定土壤中镉的新方法。研究了抗坏血酸-磺胺双络合体系对方法的增效作用,以及Ni2+对测定的显著增感作用;探讨了氢化物发生的反应机理,并应用核磁共振仪对机理进行实验验证。该方法测镉的最佳条件为:以3%HCl为载流,20g/LKBH4溶液为还原剂,在0.05%抗坏血酸+0.05%磺胺双络合试剂+0.1mg/LNi2+体系中,镉的线性范围为2～40μg/L,相关系数(r)0.9993,检出限为0.08μg/L,RSD4.8%(n=14)。应用本方法测定了4种国家土壤标准物质中镉的含量,结果与标准值吻合。     

微波灰化-原子荧光光谱法测定卷烟纸中镉

卷烟纸样品于瓷坩埚中,放入微波灰化系统中在450℃灰化20min,残渣加入体积分数为2.5%盐酸溶液溶解转入50mL容量瓶中定容后,供原子荧光光谱仪测定卷烟纸中镉的含量。在优化的仪器条件下,镉的质量浓度在0.2～10μg.L-1范围内与其荧光强度呈线性关系,方法的检出限(3s/k)为0.018μg.L-1。方法用于分析卷烟纸样品,所得回收率在94.4%～98.4%之间。方法的日内和日间相对标准偏差(n=7)分别为2.2%和2.8%。     

金属-陶瓷电热蒸发-原子荧光法快速测定土壤中汞

研制了一种由金属-陶瓷杯和催化热解炉组成的金属-陶瓷电热蒸发(MCH-ETV)装置,将其与原子荧光光谱仪(AFS)联用,集成为一套MCH-ETV-AFS仪器系统,通过优化蒸发功率、原子化器条件、工作气体流速等参数,建立了一种直接进样快速检测土壤中汞(Hg)的方法。在最优条件下,Hg的检出限(LOD)为0.16 ng/g(进样量50 mg),在8～590 ng/g线性范围内,线性相关系数(R²)为0.996。3种土壤基体标准物质的Hg测定值在其标定的不确定度范围内,9种实际土壤样品的Hg测定值与标准方法的测定结果无显著性差异(p>0.05),回收率为96%～107%;真实土壤样品多次测定的相对标准偏差(RSD)在2%～11%之间。研究结果表明,本方法具有良好的准确度和精密度。由于无需金汞齐的富集过程,本方法在3 min内即可完成检测,采用的MCH-ETV尺寸小、功耗低(<200 W),这为进一步研发小型化测汞仪提供了新思路。     

直接进样汞镉测定仪校准方法

建立直接进样汞镉测定仪的校准方法.参考直接进样汞镉测定仪的工作原理、出厂指标及相关检测标准,对直接进样汞镉测定仪的计量性能进行探讨,直接进样汞镉测定仪的主要校准项目包括线性相关系数、检出限和测量重复性,参考指标为线性相关系数不小于0.995,汞元素的检出限不大于0.02 ng,镉元素的检出限不大于0.1 ng,测量重复...     

Determination of cadmium in rice and water by tungsten coil electrothermal vaporization-atomic fluorescence spectrometry and tungsten coil electrothermal atomic absorption spectrometry after cloud point extraction

In this work, the microsampling nature of tungsten coil electrothermal vaporization Ar/H₂ flame atomic fluorescence spectrometry (W-coil ETV-AFS) as well as tungsten coil electrothermal atomic absorption spectrometry (W-coil ET-AAS) was used with cloud point extraction (CPE) for the ultrasensitive determination of cadmium in rice and water samples. When the temperature of the extraction system is higher than the cloud point temperature of the selected surfactant Triton X-114, the complex of cadmium with dithizone can be quantitatively extracted into the surfactant-rich phase and subsequently separated from the bulk aqueous phase by centrifugation. The main factors affecting the CPE, such as concentration of Triton X-114 and dithizone, pH, equilibration temperature and incubation time, were optimized for the best extract efficiency. Under the optimal conditions, the limits of detection for cadmium by W-coil ETV-AFS and W-coil ET-AAS were 0.01 and 0.03 μg L⁻¹, with sensitivity enhancement factors of 152 and 93, respectively. The proposed methods were applied to the determination of cadmium in certified reference rice and water samples with analytical results in good agreement with certified values.     

Rapid determination of lead and cadmium in biological fluids by electrothermal atomic absorption spectrometry using Zeeman correction

Procedures for the electrothermal atomic absorption spectrometric determination of lead and cadmium in urine, serum and blood are developed. For serum and blood, the samples are diluted by incorporating 0.015% (w/v) Triton X-100 and 0.1% (w/v) ammonium dihydrogenphosphate to the solutions, which are then introduced directly into the furnace. A solution containing 15% (w/v) hydrogen peroxide and 0.65% (w/v) nitric acid is also introduced into the atomizer by means of a separate injection. Zeeman-based correction is recommended. Both conventional and fast-heating programs are discussed. Calibration is carried out using the standard additions method. The reliability of the procedures is checked by analyzing three certified reference materials and by recovery studies.     

Determination of trace impurities in titanium dioxide by direct solid sampling electrothermal atomic absorption spectrometry

A true direct solid sampling electrothermal atomic absorption spectrometry method with Zeeman-effect background correction (Analytik Jena ZEEnit 60 AAS) was developed for the determination of As, Cd, Hg, Pb, Sb and Zn in powdered titanium dioxide of pharmaceutical, food and cosmetics grade. The interaction of the titanium matrix and graphite surface of the sample carrier boat in a transversely heated graphite tube atomizer was investigated. Conversion of titanium dioxide to interfering TiO₂–TiC-liquid phase, running out the sampling boat, was observed at temperatures above 2000 °C. The temperature program was optimized accordingly for these volatile analytes in atomization and cleaning steps in order to prevent this interference and to prolong significantly the analytical lifetime of the boat to more than one thousand runs. For all elements, calibration by aqueous standard addition method, by wet-chemically analyzed samples with different content of analytes and/or by dosing one sample in different amounts, were proved as adequate quantification procedures. Linear dynamic calibration working ranges can be considerably expanded up to two orders of magnitude within one measurement run by applying three-field dynamic mode of the Zeeman background correction system. The results obtained by true direct solid sampling technique are compared with those of other independent, mostly wet-chemical methods. Very low limits of detection (3σ criterion) of true solid sampling technique of 21, 0.27, 24, 3.9, 6.3 and 0.9 ng g^− 1 were achieved for As, Cd, Hg, Pb, Sb and Zn, respectively.     

A direct solid sampling electrothermal atomic absorption spectrometry method for the determination of silicon in biological materials

A solid sampling electrothermal atomic absorption spectrometry method for direct determination of trace silicon in biological materials was developed and applied to analysis of pork liver, bovine liver SRM 1577b and pure cellulose. The organic matrix was destroyed and expelled from the furnace in the pyrolysis stage involving a step-wise increasing the temperature from 160 °C to 1200 °C. The mixed Pd/Mg(NO₃)₂ modifier has proved to be the optimum one with respect to the achievement of maximum sensitivity, elimination of the effect of the remaining inorganic substances and the possibility of using calibration curves measured with aqueous standard solutions for quantification. For the maximum applicable sample amount of 6 mg, the limit of detection was found to be 30 ng g^− 1. The results were compared with those obtained by different spectrometric methods involving sample digestion, by electrothermal atomic absorption spectrometry using slurry sampling, by wavelength dispersive X-ray fluorescence spectrometry and by radiochemical neutron activation analysis. The method seems to be a promising one for analysis of biological materials containing no significant fraction of silicon in form of not naturally occurring volatile organosilicon compounds. The still incessant serious limitations and uncertainties in the determination of trace silicon in solid biological materials are discussed.     

氢化物发生-原子荧光光谱法间接测定痕量碘的研究

提出了氢化物发生-原子荧光光谱法间接测定痕量碘的新方法,在弱酸性介质中,以Ⅰ--[Cd(Phen)3]2 -硝基苯为萃取体系,经0.24 mol/L的HCl反萃取后,用原子荧光光谱法测定镉量,从而间接测定碘.方法的线性范围为0～20 μg/L;相对标准偏差为8.5%;检出限为0.8 μg/L;回收率为74.63%～90.80%.方法已用于测定自来水中的碘量.     

Direct determination of cadmium in urine by electrothermal atomic absorption spectrometry after in situ electrodeposition

Determination of cadmium in urine by ETAAS suffers from severe interferences deteriorating the precision and accuracy of the analysis. Electrodeposition step prior to ETAAS allows to avoid interferences and makes cadmium determination possible even at ultratrace levels. The proposed procedures involve electrolytic deposition of cadmium from acidified urine on previously electrolytically deposited palladium film on a graphite atomizer tube, followed by removal of residual solution, pyrolysis and atomization. Both electrodeposition processes take place in a drop of the respective solution (palladium nitrate modifier and acidified urine, respectively), when Pt/Ir dosing capillary serves as an anode and the graphite tube represents a cathode. The voltage is held at −3.0 V. Matrix removal is then accomplished by withdrawal of the depleted sample solution from the tube (procedure A) or the same but followed by rinsing of the deposit with 0.2 mol l⁻¹ HNO₃ (procedure B). The accuracy of both procedures was verified by recovery test. Detection limits 0.025 and 0.030 μg Cd/l of urine were achieved for A and B procedures, respectively. Both procedures are time consuming. The measurement cycle represents 5 and 7 min for A and B procedures, respectively.     

Feasibility of employing permanent chemical modifiers for the determination of cadmium in coal using slurry sampling electrothermal atomic absorption spectrometry

Iridium and ruthenium, alone and in combination with tungsten, thermally deposited on the platform of a transversely heated graphite tube, were investigated for their suitability as permanent chemical modifiers for the determination of cadmium in coal slurries by electrothermal atomic absorption spectrometry (ET AAS). The conventional mixed palladium and magnesium nitrates (Pd–Mg) modifiers, added in solution, were also investigated for comparison. The latter one showed the best performance for aqueous solutions, and the mixed W–Ir and W–Ru permanent modifiers had the lowest stabilizing power. All of the investigated modifiers lost some of their stabilizing power when coal slurries were investigated. The Pd–Mg modifier, pure Ir and Ru, and a mixture of 300 μg W + 200 μg Ir could stabilize Cd at least to a pyrolysis temperature of 600 °C, whereas all the other combinations already failed at temperatures above 500–550 °C. Additional investigations of the supernatant liquid of the slurries supported the assumption that the high acid concentration of the slurries and/or a concomitant leaching out of the coal might be responsible for the reduced stabilizing power of the modifiers. The maximum applicable pyrolysis temperature of 600 °C was not sufficient to reduce the background absorption to a manageable level in the majority of the coal samples. High-resolution continuum source ET AAS revealed that the continuous background absorption was exceeding values of A = 2, and was overlapping with the analyte signal. Although the latter technique could correct for this background absorption, some analyte was apparently lost with the rapidly vaporizing matrix so that the method could not be considered to be rugged. A characteristic mass of 1.0 pg and a detection limit of 0.6 ng g^− 1 could be obtained under these conditions.     

Chromium determination in pharmaceutical grade barium sulfate by solid sampling electrothermal atomic absorption spectrometry with Zeeman-effect background correction

A procedure for chromium (Cr) determination in pharmaceutical grade barium sulfate by direct solid sampling electrothermal atomic absorption spectrometry (DSS-ET AAS) with Zeeman-effect background correction was developed. Operational conditions for the proposed procedure and the use of citric acid, ammonium phosphate, palladium and magnesium nitrate as chemical modifiers were evaluated. Pyrolysis and atomization temperatures were set at 1500 and 2400 °C, respectively and the use of matrix modifiers did not improve these conditions. Graphite platform presented high degradation rate, but minima changes were observed in the sensitivity or signal profile. Samples (0.3-1 mg) were weighted and introduced into the furnace using a manual solid sampling system. The linear concentration range of the calibration curve was from 100 to 1800 pg (R² > 0.995). The characteristic mass was 7.7 pg and the limit of detection was 2.4 pg. Chromium concentration in commercial samples ranged from 0.45 to 1.06 μg g⁻¹ and these results were confirmed by standard addition method. The mean reproducibility was 12% (n = 20 in a 3-day period) and repeatability was less than 9%. Results obtained using inductively coupled plasma optical emission spectrometry and conventional electrothermal atomic absorption spectrometry after extraction with HNO₃ were around 20% lower than those obtained by the proposed procedure. It was assumed that the low results were due to incomplete extraction even using hard conditions related to temperature and pressure. The proposed procedure by DSS-ET AAS provided some advantages related to recommended pharmacopoeias methodology, as lower risks of contamination and analyte losses, higher specificity, accuracy and sensitivity, no toxic or unstable reagents are required, and calibration with aqueous standards was feasible.     

Comparison of direct solid sampling and slurry sampling for the determination of cadmium in wheat flour by electrothermal atomic absorption spectrometry

Two analytical methods for the determination of cadmium in wheat flour by electrothermal atomic absorption spectrometry without prior sample digestion have been compared: direct solid sampling analysis (SS) and slurry sampling (SlS). Besides the conventional modifier mixture of palladium and magnesium nitrates (10 μg Pd + 3 μg Mg), 0.05% (v/v) Triton X-100 has been added to improve the penetration of the modifier solution into the solid sample, and 0.1% H₂O₂ in order to promote an in situ digestion for SS. For SlS, 30 μg Pd, 12 μg Mg and 0.05% (v/v) Triton X-100 have been used as the modifier mixture. Under these conditions, and using a pyrolysis temperature of 800 °C, essentially no background absorption was observed with an atomization temperature of 1600 °C. About 2 mg of sample have been typically used for SS, although as much as 3-5 mg could have been introduced. In the case of SlS multiple injections had to be used to achieve the sensitivity required for this determination. Calibration against aqueous standards was feasible for both methods. The characteristic mass obtained with SS was 0.6 pg, and that with SlS was 1.0 pg. The limits of detection were 0.4 and 0.7 ng g⁻¹, the limits of quantification were 1.3 and 2.3 ng g⁻¹ and the relative standard deviation (n = 5) was 6-16% and 9-23% for SS and SlS, respectively. The accuracy was confirmed by the analysis of certified reference materials. The two methods were applied for the determination of cadmium in six wheat flour samples acquired in supermarkets of different Brazilian cities. The cadmium content varied between 8.9 ± 0.5 and 13 ± 2 ng g⁻¹ (n = 5). Direct SS gave results similar to those obtained with SlS using multi-injections; the values of both techniques showed no statistically significant difference at the 95% confidence level. Direct SS was finally adopted as the method of choice, due to its greater simplicity, the faster speed of analysis and the better figures of merit.     

Simultaneous determination of bromine and chlorine in coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis

A new method for the direct analysis of coal using electrothermal vaporization inductively coupled plasma mass spectrometry and direct solid sample analysis was developed, aiming at the determination of Br and Cl. The procedure does not require any significant sample pretreatment and allows simultaneous determination of both elements to be carried out, requiring small mass aliquots of sample (about 0.5 mg). All operating parameters, including carrier gas flow-rate and RF power, were optimized for maximum sensitivity. The use of modifiers/aerosol carriers (Pd, Pd + Al and Pd + Ca) was evaluated, and the mixture of Pd and Ca was chosen, allowing pyrolysis and vaporization temperatures of 700 °C and 1900 °C, respectively. Chlorine was accurately determined using calibration against solid standards, whereas Br could also be determined using calibration against aqueous standard solutions. The limits of quantification were 0.03 μg g⁻¹ for Br and 7 μg g⁻¹ for Cl, and no spectral interferences were observed.