Determination of zinc in food using atomic fluorescence spectrometry by hydride generation from organized media

A method was proposed for the determination of zinc by atomic fluorescence spectrometry with hydride generation from surfactant-based organized media. The ability of different nature micelles to improve hydride generation of zinc was investigated using an intermittent flow hydride generator and the possible mechanism was discussed. The advantages of hydride generation from the organized media of cetyltrimethylammonium bromide (CTAB) were contrasted with that from aqueous media in sensitivity and precision of the zinc determination. The micellar media of CTAB improved the hydride generation processes of zinc both thermodynamically and kinetically. In addition some transition metals, presumably metal borides, were found to catalyze the hydrogenation of zinc. The proposed method has been validated by the determination of zinc in the certified reference materials using the standard addition method with satisfactory result.     

Application of photochemical reactions of Se in natural waters by hydride generation atomic fluorescence spectrometry

A simple, sensitive and accurate method for selenium speciation in natural waters is proposed. The principle of this method is based on recently discovered photochemical reactions of Se(IV) and organic selenium in different aqueous solutions. The speciation of all selenium species was performed with hydride generation-atomic fluorescence spectrometry. Only one pre-reduction step is needed in this procedure, which can greatly reduce the risk of contamination, minimize the analytical work and improve the quality of selenium speciation. In this paper, a comparison is made between the proposed method and a previous method [A.G. Cutter, Anal. Chim. Acta 98 (1978) 59]. In this proposed protocol, Se(IV) was directly measured in 3.0 M HCl. Se(IV) + org-Se was measured directly after a UV irradiation (300 nm) for 2.5 h in a 1.0% (v/v) HNO₃-2.0% (v/v) HCl matrix. Total selenium was obtained in another aliquot sample after a UV irradiation in the 3.0 M HCl. No pre-concentration, separation or more sophisticated instruments are required.     

顺序注射氢化物发生-原子荧光光谱法同时测定硒和砷的研究

建立了一种顺序注射氢化物发生-原子荧光光谱法测定试样中Se和As的方法,同时讨论了共存离子的干扰情况.在最佳实验条件下,Se和As的检出限分别为0.16和0.095 μg/L,加标回收率为92.4%～104.7%.     

Determination of total arsenic in seawater by hydride generation atomic fluorescence spectrometry

In this work, the determination of total As in seawater by hydride generation atomic fluorescence spectrometry was studied. The influence of the chemical, flow and instrumental parameters were investigated and optimized. The pre-reduction of As(V) to As(III) was performed using KI plus ascorbic acid in 3.5 mol L^− 1 HCl medium. No multiplicative interference was present and external aqueous calibration could be used. The limit of detection was 36 ng L^− 1, while the repeatability was 2% (n = 10), at a 500 ng L^− 1 concentration level. The sample throughput was 15 h^− 1 if triplicate measurements were made. The accuracy was assessed by the analysis of a seawater certified reference material and excellent agreement between the obtained and certified values was verified. The procedure was used for the analysis of seawater offshore samples collected at the Brazilian coast and results ranging from 860 to 1200 ng L^− 1 were found.     

Determination of arsenic in dinosaur skeleton fossils by hydride generation atomic fluorescence spectrometry

Hydride generation atomic fluorescence spectrometry was for the first time utilized to determine trace toxic element arsenic in the skeleton fossils of four dinosaurs unearthed in Sichuan Province of China. The instrumental limit of detection (LOD) for arsenic was 0.03 μg/L under optimal experimental conditions, which compared favorably to that by ICP-AES and ETAAS. The samples were digested with aqua regia in boiling water bath. The recoveries of standard addition were found to be from 97 to 109%, and the analytical results were found in good agreement with those by ICP-AES. It is a simple, reliable, sensitive yet relatively inexpensive analytical method, compared to ICP-AES, ICP-MS or ETAAS. Interesting analytical results were found that the arsenic concentrations were all abnormally high in the skeleton fossils. The established analytical method and the analytical results may be helpful in revealing the mystery of the mass extinction of the dinosaur fauna. The analytical results, together with other data available to date, supported the argument that the arsenic toxicosis could be a contributing factor for the mass extinction of the dinosaur fauna in Sichuan Province of China.     

Comparison of pre-reducing agents for antimony determination by hydride generation atomic fluorescence spectrometry

A systematic study of antimony reduction prior to its determination by hydride generation atomic fluorescence spectrometry (HG-AFS) was carried out. The efficiency of l-cysteine, potassium iodide and potassium iodide/ascorbic acid was studied for this purpose. The hydride generation step was optimised in the presence of those pre-reductors. From the results, l-cysteine was found to be the most suitable pre-reducing agent. Methodology was validated, obtaining detection limits lower than 90 ng l⁻¹ and repeatability and reproducibility better than 3% R.S.D. and 5% R.S.D., respectively, in all cases. In order to evaluate the methodology developed and the influence of the matrix, recovery from waters from different sources was tested by HG-AFS and also by inductively coupled plasma mass spectrometry (ICP-MS). Accuracy was assessed by analysing three water reference materials at different antimony concentration levels. The high sensitivity of the developed methodology enables it to be applied for monitoring drinking waters according to the maximum admissible concentration of antimony established by the EU Directives.     

Determination of bismuth in solid samples by hydride generation atomic fluorescence spectrometry with a dielectric barrier discharge atomizer

An atmospheric pressure dielectric barrier discharge (DBD) atomizer was investigated for bismuth (Bi) determination with hydride generation (HG) atomic fluorescence spectrometry (AFS). The characteristics of the atomizer and the effects of experimental parameters, including observation height, discharge power, flow rate of discharge gas and AFS carrier gas were optimized. The linear range of present method for Bi determination is 0.5-300.0 μg L⁻¹ with a detection limit of 0.07 μg L⁻¹ (3σ). The method was validated by the analysis of reference materials (GBW08517 and GSB-14) and the results agreed well with the reference values. The established method was applied to the determination of Bi in ore, soil and ash samples.     

电磁感应在线消化-原子荧光光谱法测定茶水中的砷

利用电磁感应加热原理,研制了在线消化还原、氢化物发生原子荧光法分析装置,实现了茶水中As量的在线测定.对各种实验参数和干扰情况进行了研究.方法的检出限为0.063 μg/L;样品分析精密度(RSD)为2.5%(n=11).     

A hydride generation atomic fluorescence spectrometric procedure for selenium determination after flow injection on-line co-precipitate preconcentration

A flow injection (FI) on-line preconcentration procedure for ultra-trace inorganic selenium was developed with detection by atomic fluorescence spectrometry. Selenium (IV) is co-precipitated with lanthanum hydroxide and collected on a PTFE beads packed column, the precipitate is afterwards dissolved with hydrochloric acid followed by hydride generation with reduction by tetrahydroborate. A thorough scrutiny was made for chemical variables and FI parameters. With a sampling volume of 3.4 ml, quantitative retention of selenium (IV) was obtained, along with an enrichment factor of 11 and a sampling frequency of 38 h^− 1. The detection limit, defined as 3 times the blank standard deviation (3σ), was 5 ng l^− 1. The precision was characterized by a RSD value of 1.2% (at the 0.5 μg l^− 1 level, n = 11). The enrichment factor was further enhanced to 20 along with a detection limit of 3 ng l^− 1, with a sample loading volume of 6.8 ml. The procedure was validated with certified reference materials and biological samples. It was also applied to the speciation of inorganic selenium in surface waters.     

Determination of As, Sb, Se, Te and Bi in milk by slurry sampling hydride generation atomic fluorescence spectrometry

A simple and fast analytical procedure has been developed for the determination of As, Sb, Se, Te and Bi in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS). Samples were treated with aqua regia for 10 min in an ultrasound water bath and pre-reduced with KBr for total Se and Te determination or with KI and ascorbic acid for total As and Sb, the determination of Bi being possible in all with or without pre-reduction. Slurries of samples, in the presence of antifoam A, were treated with NaBH₄ in HCl medium to obtain the corresponding hydrides, and AFS measurements were processed in front of external calibrations prepared and measured in the same way as samples. Results obtained by the developed procedure compare well with those found after microwave-assisted complete digestion of samples. The proposed method is simple and fast, and only 1 ml of milk is needed. The values obtained for detection limit are 2.5, 1.6, 3, 6 and 7 ng l⁻¹ for As, Sb, Se, Te and Bi respectively in the diluted samples, with average relative standard deviation values of 3.8, 3.1, 1.9, 6.4 and 1.2% for three independent analysis of a series of commercially available samples of different origin. Data found in Spanish market samples varied from 3.2±0.3 to 11.3±0.2 ng g⁻¹ As, from 3.1±0.2 to 11.6±0.4 ng g⁻¹ Sb, from 10.7±0.5 to 25.5±0.4 ng g⁻¹ Se, from 0.9±0.2 to 9.4±0.6 ng g⁻¹ Te and from 11.5±0.1 to 27.7±0.4 ng g⁻¹ Bi.     

Determination of selenium in water and soil by hydride generation atomic absorption spectrometry using solid reagents

A hydride generation method for the determination of traces of selenium at ng mL⁻¹ concentration ranges has been introduced using a solid mixture of tartaric acid and sodium tetrahydroborate. Atomic absorption spectrometry (AAS) has been used as the detection system. Several parameters such as the ratio of tartaric acid to sodium tetrahydroborate, type and amount of acid, and the reaction temperature were optimized by using 640 ng mL⁻¹ (16 ng per 25 μL) of Se(IV) standard solution. The calibration curve was linear from 20 to 1200 ng mL⁻¹ (0.5-30 ng Se(IV) per 25 μL). The relative standard deviation (%R.S.D.) of the determination was 1.93% and the detection limit was 10.6 ng mL⁻¹ (265 pg per 25 μL) of Se(IV). The reliability of the method was checked using different types of environmental samples, such as several types of water, a sample of soil and also in a kind of calcium phosphate sample by standard addition method. For conversion of Se(VI) present in real samples to Se(IV), l-cysteine was added to NaBH₄ and tartaric acid mixture. The results showed good agreement between this method and other hydride generation techniques.     

氢化物发生原子荧光法同时测定保健品中痕量锗和硒

采用微波消解样品,氢化物发生原子荧光法同时测定保健品中的锗和硒.研究了仪器条件、酸度、 KBH4浓度等对测定的影响,锗和硒的检出限为0.40和0.51 μg/L;相对标准偏差均为2.0%;回收率为77.1%～105.2%和80.0%～108.2%,已用于保健品中锗和硒的测定.     

原子荧光光谱法测定当归补血汤中的微量硒

采用氢化物发生-原子荧光光谱法测定当归、黄芪以及两种药材以不同配伍形式的水煎液中的硒量。比较了不同提取方法及磷脂类化合物对水煎液中硒溶出的影响。结果表明,氢化物发生-原子荧光光谱法测定硒的方法的回收率为93.8%~95.0%,且当归∶黄芪为1∶5配比时的水煎液中硒溶出率高于1∶1配比,证实了当归补血汤经典配方的合理性,为其临床疗效提供了有效依据。     

氢化物发生-原子荧光光谱法测定中草药中的微量砷

研究了氢化物发生-原子荧光光谱法测定中草药中微量砷的方法的最佳条件，以50g／L硫脲 50g／L抗坏血酸为预还原抗干扰剂，测定了10种中草药药品中的砷，方法检出限(3σ)为0．103μg/L，相对标准偏差为1．6％-3.2％，回收率为89．2％-112％。     

紫外光诱导化学蒸气发生-氩/氢火焰原子荧光光谱法测定丹参中硒

以紫外光诱导化学蒸气发生装置作为原子荧光光谱仪的进样系统,建立了光化学蒸气发生原子荧光光谱法测定中药材丹参中总硒含量的分析方法。研究了试剂浓度、光化学蒸气反应管等因素对硒化学蒸气发生效率的影响。仪器对硒的检出限为6.60 ng/mL,精密度(RSD)为0.6%(n=10),回收率为98%～107%。     

流动注射在线共沉淀HG-AFS测定痕量铅

建立了流动注射在线共沉淀HG-AFS测定痕量铅的分析方法。方法基于铅在碱性介质中与氢氧化镁共沉淀，沉淀收集在锥形沉淀腔中，用HCl溶洗沉淀和NaBH4反应，产生的氢化物被载气引入原子化器中进行测定。测定铅的RSD为3％(5ng/mL，n=10)，检出限为0．01ng。检出限较直接进样降低了11倍。对国家标准物质中铅的测定结果与标准值相符。     

Determination of selenium using atomically imprinted polymer (AIP) and hydride generation atomic absorption spectrometry

This paper describes selenium determination based on Se⁰ preconcentration in the imprinted polymer (synthesized with 2.25 mmol SeO₂, 4-vinylpyridine and 1-vinylimidazole) with subsequent detection on-line in HG-FAAS. During the synthesis, SeO₂ is reduced to Se (0). Therefore, there are no MIP neither IIP in the present work, thus we denominated: AIP, i.e., atomically imprinted polymers. For the optimization of analytical parameters Doehlert design was used. The method presented limit of detection and limit of quantification of 53 and 177 ng L⁻¹, respectively, and linear range from 0.17 up to 6 μg L⁻¹ (r = 0.9936). The preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 232; 0.06 mL and 58 min⁻¹ respectively. The proposed method was successfully applied to determine Se in Brazil nuts (0.33 ± 0.03 mg kg⁻¹), apricot (0.46 ± 0.02 mg kg⁻¹), white bean (0.47 ± 0.03 mg kg⁻¹), rice flour (0.47 ± 0.02 mg kg⁻¹) and milk powder (0.22 ± 0.01 mg kg⁻¹) samples. It was possible to do 12 analyzes per hour. Accuracy was checked and confirmed by analyzing certified reference material (DORM-2, dogfish muscle), and samples precision was satisfactory with RSD lower than 10%.     

Determination of tin in steels by non-dispersive atomic fluorescence spectrometry coupled with flow-injection hydride generation in the presence of L-cysteine

Flow-injection hydride generation has been coupled with a non-dispersive atomic fluorescence spectrometer for the determination of trace concentrations of tin. The use of L-cysteine in stannane generation enhances the atomic fluorescence signal for tin. In addition, it appears that the flow-injection method allows the use of a wider range of acid concentrations, and hence interference from transition elements is also reduced. An absolute detection limit of 1.3 ng was achieved with a 0.5 ml sample. Ten determinations of a solution containing 100 ng ml⁻¹ of tin(H) generated a relative standard deviation of 1.8%. The linear dynamic range of the calibration curve extended over three orders of magnitude and sample throughput rate was 144 samples h⁻¹. Application of the proposed technique is demonstrated by the determination of tin in low alloy steel standard reference materials.     

氢化物发生-原子荧光光谱法测定蔬菜中的镉

研究了以8-羟基喹啉与钴离子作为协同增效剂,氢化物发生-原子荧光光谱测定蔬菜中镉的方法.得到测镉的最佳条件是: 3%HCl 1 mg/L Co2 5 mg/L 8-羟基喹啉体系.本法线性范围0.5～20 μg/L,检出限为0.03 μg/L,RSD为2.5%.本法应用于测定蔬菜中镉的回收率为92%～105%.     

Flame-in-gas-shield miniature flame hydride atomizers for ultra trace element determination by chemical vapor generation atomic fluorescence spectrometry

Flame-in-gas shield miniature hydride atomizers (FIGS) have been investigated and evaluated in view of their alternative use to miniature diffusion flame hydride atomizer (MDF) to determination of hydride forming elements by atomic fluorescence spectrometry (AFS). Chemical vapour generation (CVG) by aqueous phase derivatization by NaBH₄ in a continuous flow generator (CF) was employed for the generation of volatile hydrides of As, Sb, Bi, Se, Te and Sn. A dispersive AFS apparatus using electrodeless discharge lamps (EDL) as the excitation sources has been employed for both spectra acquisition and analytical determinations. The characteristics of FIGS in terms of background emission spectra, most intense AF spectral lines and limits of detection were compared with those of most popular MDF. FIGS presents a lower background emission with respect to MDF, allowing also the control of the molecular fluorescence of OH radicals in the determination of bismuth. Limits of detection for FIGS compare very well with to those obtained by MDF giving improvement factor of 5.5, 4.4, 3.6, 3.6, 0.7 an 0.5 for Bi, As, Se, Son, Te and Sb. Accuracy of FIGS has proven by determination of arsenic and antimony in seawater (NASS-5) and river water (SRLS-4) certified reference materials and bismuth in unalloyed copper (CuV 398, CuVI 399) standard reference materials by dispersive CVG-AFS.