Determination of trace elements in liquid aspartame sweeteners by ICP OES and ICP-MS following acid digestion

In order to determine inorganic constituents and contaminants in liquid aspartame sweeteners, different brands of this product were analyzed by ICP OES and ICP-MS. The samples were submitted to acid digestion and parameters such as internal standardization and wavelengths, in the case of ICP OES, and a recovery test were evaluated. The analytes studied were As, Ca, Cd, Co, Cu, K, Fe, Mg, Mn, Na, Ni, Pb, Se and Zn. Since there is not a certified reference material for sweeteners, the accuracy of the proposed method was evaluated by recovery tests and the values were in the range of 90–110% for the majority of the analytes. The detection limits for the elements determined by ICP OES were in the range 0.01 (Mn)– 2.0 (K) μg g⁻¹ while those determined by ICP-MS were 0.001 μg g⁻¹ for all the elements except Mn and As (0.002 μg g⁻¹). The relative standard deviations were below 12% for ICP OES and below 14% for ICP-MS determinations. The mean concentration of the elements detected by ICP OES (Ca, Fe, K, Mg, Na, and Zn) varied according to the brand. The other analytes, were determined by ICP-MS. For these elements, a significant variation in their concentrations was also found for different samples, except for Co and Ni. The use of both multielemental techniques allowed the evaluation of the inorganic composition and the rapid determination of several elements in aspartame sweeteners, with adequate accuracy.     

Determination of platinum and rhodium in dust and plant samples using microwave-assisted sample digestion and ICP-MS

The platinum group elements (PGEs), particularly platinum, palladium and rhodium, are nowadays increasingly emitted into the environment from automotive catalytic converters. Thus, a method for the determination of PGEs (especially platinum and rhodium) in dust and plant samples was developed. The developed method was based on microwave-assisted sample digestion and inductively coupled plasma mass spectrometric (ICP-MS) determination. Spectral interferences in ICP-MS determination were corrected using mathematical correction equations based on signal ratio measurement. In addition, platinum and rhodium concentrations in the digested dust samples were also determined after Te coprecipitation without correction of the interferences. The results for platinum and rhodium in reference materials (NIST SRM 2557, recycled monolith autocatalyst and BCR-723, road dust) were in good agreement with the certified values. Preliminary results for the anthropogenic platinum and rhodium emissions in Oulu, northern Finland, based on dust and plant samples, indicated a common traffic-related source of these metals.     

Pressurized wet digestion in open vessels

The High Pressure Asher (HPA-S) was adapted with a Teflon liner for pressurized wet digestion in open vessels. The autoclave was partly filled with water containing 5% (vol/vol) hydrogen peroxide. The digestion vessels dipped partly into the water or were arranged on top of the water by means of a special rack made of titanium or PTFE-coated stainless steel. The HPA-S was closed and pressurized with nitrogen up to 100 bars. The maximum digestion temperature was 250 °C for PFA vessels and 270 °C for quartz vessels. Digestion vessels made of quartz or PFA-Teflon with volumes between 1.5 mL (auto sampler cups) and 50 mL were tested. The maximum sample amount for quartz vessels was 0.5–1.5 g and for PFA vessels 0.2–0.5 g, depending on the material. Higher sample intake may lead to fast reactions with losses of digestion solution. The samples were digested with 5 mL HNO₃ or with 2 mL HNO₃+6 mL H₂O+2 mL H₂O₂. The total digestion time was 90–120 min and 30 min for cooling down to room temperature. Auto sampler cups made of PFA were used as digestion vessels for GFAAS. Sample material (50 mg) was digested with 0.2 mL HNO₃+0.5 mL H₂O+0.2 mL H₂O₂. The analytical data of nine certified reference materials are also within the confidential intervals for volatile elements like mercury, selenium and arsenic. No cross contamination between the digestion vessels could be observed. Due to the high gas pressure, the diffusion rate of volatile species is low and losses of elements by volatilisation could be observed only with diluted nitric acid and vessels with large cross section. In addition, cocoa, walnuts, nicotinic acid, pumpkin seeds, lubrication oil, straw, polyethylene and coal were digested and the TOC values measured. The residual carbon content came to 0.2–10% depending on the sample matrix and amount.     

湿法消解-电感耦合等离子体质谱(ICP-MS)法测定大气降尘中7种重金属

为精准防控大气降尘污染,提供其重金属检测方法。重点考察了样品前处理中混合酸体系选择和最佳酸用量比对实验。在最优条件下建立了混合酸（硝酸、氢氟酸、盐酸和高氯酸）湿法消解大气降尘样品和电感耦合等离子体质谱仪进行7种重金属（铊、铅、镉、铬、铜、锌和镍）含量测试的实验方法。实验结果显示7种重金属在一定的浓度范围内线性关系好,线性系数均大于0.999,7种重金属方法检出限为0.02 mg/kg～2.0 mg/kg,实际样品6次测定相对标准偏差为1.1 %～5.7 %,加标回收回收率为87.7 %～108.9 %。该方法经济环保、准确快捷,可作为大气沉降重金属检测参考方法。     

The role of different soil sample digestion methods on trace elements analysis: a comparison of ICP-MS and INAA measurement results

The measurement of trace-element concentration in soil, sediment and waste, is generally a combination of a digestion procedure for dissolution of elements and a subsequent measurement of the dissolved elements. “Partial” and “total” digestion methods can be used in environmental monitoring activities. To compare measurement results obtained by different methods, it is crucial to determine and to maintain control of the bias of the results obtained by these methods. In this paper, ICP-MS results obtained after matrix digestion with modified aqua regia (HCl+HNO₃+H₂O₂) method and two “total” digestion methods (microwave aqua regia+HF and HNO₃+HF) are compared with those obtained by instrumental neutron activation analysis, a non-destructive analytical method for the determination of the total mass concentrations of inorganic components in environmental matrices. The comparison was carried out on eight agricultural soil samples collected in one test area and measured by k₀-INAA and ICP-MS to determine As, Co, Cr, Sb and Zn mass concentration. The bias of results for As, Cd, Co, Cr, Cu, Ni, Pb, Sb and Zn of the three digestion methods were assessed using selected measurement standards. This paper highlights that the digestion procedure is an integral part of the measurement and can affect the measurement result in environmental analysis.     

微波消解-ICP-MS测定40种中药材中的5种有毒元素

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定中药材中Cu,As,Cd,Hg,Pb 5种有毒元素的方法,采用In为内标,利用其回收率对以上5种元素的测定结果进行校正。该方法对5种元素的检出限分别为0.063,0.015,0.018,0.006,0.056μg/g,相对标准偏差为0.2%~4.0%,In元素加标回收率为96.7%~104.5%,说明该方法灵敏度高,结果准确。利用该方法对40种不同产地中药材中5种有毒元素进行了测定,结果表明中药材中有毒元素超标问题相当严重,必须在中药材生产过程中予以高度重视。     

电感耦合等离子体质谱法测定海洋沉积物中34种痕量元素

用电感耦合等离子体质谱法测定海洋沉积物中34种痕量元素,样品于聚四氟乙烯封闭坩埚中用氢氟酸和硝酸溶解,运用干扰方程校正光谱干扰,用内标校正消除基体影响。方法检出限(3s/k)在0.046～160 ng.g-1之间。通过分析4个海洋沉积物标准物质对所提出方法的准确度和精密度做了考核,所得测定结果与标准物质的认定值相吻合,各元素测定结果的相对标准偏差均小于10%。     

电感耦合等离子体质谱法测定原油中微量元素

原油样品用硝酸和过氧化氢经高压密闭消解罐消解处理,采用电感耦合等离子体质谱法测定其中镁、铝、钒、铬、镍、铜、锌、钼、镉和铅等10种微量元素的含量。10种元素的检出限(3s)在0.012～0.300μg·g~(-1)之间。方法用于S-21油标准样品分析,测定值与认定值相吻合,相对标准偏差(n=5)在0.5%～5.0%之间。10种元素的回收率在93.3%～116.0%之间。     

On the determination of platinum group elements in environmental materials by inductively coupled plasma mass spectrometry and microwave digestion

The interferences from Cd, Cu, Hf, Pb, Sr, Zn, Zr and Y on the inductively coupled plasma quadrupole mass spectrometry (ICP-MS) determination of Pt, Pd, Rh, Ru and Ir in geological (Pt-ore SARM-7, abundance range for platinum metals 0.07-3.74 μg/g) and environmental samples (sediment JSd-2 abundance range for Pt and Pd 0.0167-0.021 μg/g; road dust and plant sample) are evaluated using model solutions, real samples and comparison to inductively coupled plasma atomic emission spectrometry (ICP-AES) results. Pt, Rh, Ru and Ir can be determined usually after introduction of corrections for the interference in all investigated materials though in sediments the direct determination of Pt might be a problem depending on the actual Hf concentrations. The direct determination of Pd (after microwave-assisted acid digestion) is possible in ores using all investigated isotopes (, , ), in plants using and correction for the interferences of Zr, Mo and Cd, and not possible in sediments and road dust. Therefore, we developed a procedure for isolation of Pd using its diethyl-dithio-carabamate (DDTC) complex. The detection limits for Pt, Pd and Ir are 0.015 ng/g, and for Ru and Rh 0.03 ng/g.     

Evaluation of oxygen pressurized microwave-assisted digestion of botanical materials using diluted nitric acid

The feasibility of diluted nitric acid solutions for microwave-assisted decomposition of botanical samples in closed vessels was evaluated. Oxygen pressurized atmosphere was used to improve the digestion efficiency and Al, Ca, K, Fe, Mg and Na were determined in digests by inductively coupled plasma optical emission spectrometry (ICP OES). Efficiency of digestion was evaluated taking into account the residual carbon content (RCC) and residual acidity in digests. Samples were digested using nitric acid solutions (2, 3, 7, and 14 mol L⁻¹ HNO₃) and the effect of gas phase composition inside the reaction vessels by purging the vessel with Ar (inert atmosphere, 1 bar), air (20% of oxygen, 1 bar) and pure O₂ (100% of oxygen, 1 bar) was evaluated. The influence of oxygen pressure was studied using pressures of 5, 10, 15 and 20 bar. It was demonstrated that a diluted nitric acid solution as low as 3 mol L⁻¹ was suitable for an efficient digestion of sample masses up to 500 mg of botanical samples using 5 bar of oxygen pressure. The residual acidities in final digests were lower than 45% in relation to the initial amount of acid used for digestion (equivalent to 1.3 mol L⁻¹ HNO₃). The accuracy of the proposed procedure was evaluated using certified reference materials of olive leaves, apple leaves, peach leaves and pine needles. Using the optimized conditions for sample digestion, the results obtained were in agreement with certified values. The limit of quantification was improved up to a factor of 14.5 times for the analytes evaluated. In addition, the proposed procedure was in agreement with the recommendations of the green chemistry once it was possible to obtain relatively high digestion efficiency (RCC < 5%) using only diluted HNO₃, which is important to minimize the generation of laboratory residues.     

Epigenetics: an important challenge for ICP-MS in metallomics studies

Trace metal analysis has been long regarded as one of the principle tasks in areas of chemical analysis. At the early stage of instrumental development, total concentration was assessed in a variety of samples, yielding results, among others, for environmental, biological, and clinical samples. With the power of newer analytical techniques, such as inductively coupled plasma mass spectrometry (ICP-MS), accurate quantitative results can now be obtained at ultra-trace levels not only for metals, but also for metalloids and several non-metals. Even though the importance of trace elements in many biological processes is widely accepted, the elucidation of their biological pathways, understanding specific biological functions, or possible toxicological aspects is still a challenge and a driving force to further develop analytical methodology. Over the past decades, the scientific interest has moved from total element determination to include speciation analysis, which provides quantitative information of one or more individual element species in a sample. More recently, metallomics has been introduced as a more expanded concept, in which the global role of all metal/metalloids in a given system is considered. Owing to the multi-elemental focus of metallomics research, the use of ICP-MS becomes indispensable. Furthermore, considering the biological role of metals/metalloids and the use of elements as internal or external molecular tags, epigenetics should be considered as an important emerging application for metallomics studies and approaches. Among a variety of epigenetic factors, essential nutrients, but also environmental toxins, have been shown to affect DNA methylation, modification of histone proteins, and RNA interference, all of them being implicated in cancer, cardiovascular disease, and several inherited conditions. Recent studies suggest that epigenetics may be a critical pathway by which metals produce health effects. In this Trends article, the basic epigenetic concepts are introduced, followed by the early applications of ICP-MS classified as: (i) detection of ³¹P as a natural element tag for DNA, (ii) analysis of DNA adducts with metal-based drugs, (iii) element species as epigenetic factors.     

石墨消解-电感耦合等离子体质谱(ICP-MS)法测定铜精矿中汞的含量

称取0.2g样品于50mL样品管中,以5mL硝酸-盐酸(1∶1)混合溶液为溶剂,采用石墨消解仪对样品进行前处理。以159 Tb作内标元素补偿基体效应,用电感耦合等离子体质谱(ICP-MS)法对铜精矿中的202 Hg进行测定。结果显示,在0～50μg/L的浓度范围内,校准曲线线性相关系数在0.999 9以上,方法检出限0.019μg/L。对铜精矿标准样品的检测结果与标准值相符。铜精矿中汞的浓度在0.94～15.06μg/g时,与直接测汞仪检测结果对比基本一致。     

电感耦合等离子体质谱(ICP-MS)法测定农产品样品中6种痕量元素

建立了电感耦合等离子体质谱(ICP-MS)法测定果蔬类、大米等农产品样品中痕量元素的方法.样品通过HNO3-H2 O2混酸体系微波消解,以Rh作为内标溶液消除基体干扰,在仪器最佳条件下测定植物样中镉、铅、铬、铜、镍、锌6种痕量元素.方法的检出限为0.002～0.5μg/g;相对标准偏差(RSD)为0.84％ ～7.4％...     

ICP-MS Method Validation for the Analysis of Trace Elements in Illicit Heroin

The analysis of the trace elements present in the street doses of heroin has currently been undertaken with a dual aim: to estimate the elemental compositions and to cluster the case samples. Inductively coupled plasma-mass spectrometry was optimized to quantify 18 trace elements simultaneously. The method presented high repeatability and reproducibility for the target elements. The linear concentration ranges achieved linearity with r² > 0.9975. The limits of detection (LOD) were sufficiently low for almost all the elements except for Ca (LOD = 100 ppb). The limit of quantification (LOQ) for each element was also found acceptable. All target elements show mean recoveries between 92%–108%. Other major findings of this study including intra-sample (RSD < 5%) and inter-sample (RSD < 14%) precisions, sample weight test (≥30 mg), dissolution vessels, and sample filtration are also reported. The capability of the optimized method was assessed by using forty case samples. With their elemental compositions statistical classification of these case samples is also discussed herein.     

Sample Preparation for Determination of Rare Earth Elements in Geological Samples by ICP-MS: A Critical Review

The presence of rare earth elements (REE) in geological materials provides important information about the formation and the geochemical processes that rocks undergo. Therefore, there is a constant necessity for accurate data and reliable and fast analytical methods. However, the low concentrations of these elements typically found in rocks require quantification by sufficiently sensitive techniques, such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The preparation of these samples to the introduction in ICP-MS is a critical part of the process. Traditional wet dissolution methods, such as acid digestion or alkaline fusion followed by dissolution are mostly employed. The acid digestion requires a mixture of strong acids due to the presence of low soluble constituents common in rock samples, such as silicates or clays. The alkaline fusion is fast and efficient, but the dissolution of the melted material results in solutions with a high amount of total dissolved solids (TDS), which can be a problem due to the possibility of deposition in parts of the ICP-MS. Other instrumental approaches have been spread rapidly, as the coupling of a laser ablation accessory or an electrothermal vaporizer to the ICP-MS, as they can allow the direct sample introduction, or at least with minimum preparation. This paper presents a review of sample preparation methods, aimed at the quantification of rare earth elements by ICP-MS and focusing on works published in the last decade.     

微波消解-电感耦合等离子体质谱(ICP-MS)法同时测定土壤中11种金属元素

称取0.25g样品加入5 mL硝酸和2 mL氢氟酸,用微波消解技术对样品进行前处理.以Re作为As、Pb、Tl的内标,Rh作为Cd、Co、Cr、Ni的内标,Bi作为Be、Cu、Zn的内标,Tb作为V的内标,建立了KED模式下微波消解电感耦合等离子体质谱(ICP-MS)法同时测定土壤中Be、As、Cd、Co、Cr、Cu、...     

微波消解-电感耦合等离子体质谱法(ICP-MS)同时测定土壤中11种金属元素

称取0.25 g样品加入5ml硝酸和2ml氢氟酸,用微波消解技术对样品进行前处理。以Re作为As、Pb、Tl的内标,Rh作为Cd、Co、Cr、Ni的内标,Bi作为Be、Cu、Zn的内标,Tb作为V的内标,建立了KED模式下可同时测定土壤中Be、As、Cd、Co、Cr、Cu、Ni、Pb、Tl、V、Zn 11种金属元素的微波消解ICP-MS方法。该方法线性关系良好,线性相关系数均在0.9990以上,检出限为0.002mg/kg-0.054 mg/kg。检测土壤标准物质GSS-17、GSS-18验证方法准确性,结果显示测定值均在标准差允许范围内,相对标准偏差在0.29%-5.33%,是一种快速、可靠的土壤多种金属元素检测方法。     

电感耦合等离子体质谱研究洪湖湿地沉积柱中元素纵向分布

采集洪湖湿地两个具有代表性的湖底沉积柱进行对比,应用电感耦合等离子体质谱（ICP—MS）考察了沉积柱中微量元素及稀土元素的纵向分布特征。不同簇类的微量元素在两个沉积柱中呈现不同的纵向分布特征,微量元素富集层位存在明显的差异,表明沉积柱中微量元素的富集与沉积环境相关,直接受长江水流和交换影响的沉积柱（S1）比受洪湖湿地自身演变影响的沉积柱（S2）有更接近表层的富集层位。两个沉积柱纵向的稀土元素配分曲线呈现相似的分布特性,但分散程度不同,表明其具有相同的物源、不同的沉积环境。沉积柱中微量元素及稀土元素的纵向分布特征可以直接记录人类现代工农业活动对洪湖湿地的影响。     

微波消解-ICP/MS测定烤烟中微量元素含量

以3 mL HNO3和2 mL H2O2的混合消解液对烟草样品进行微波消解,采用电感耦合等离子体质谱测定了烤烟中的Mn、Zn、Cu、Se、N i、Co、Cr、As、Cd、Pb 10种微量元素的含量.结果表明：方法的检出限均低于0.02μg/g,各元素测定的RSD（n=5）均小于3%,样品加标回收率为97.35%-101.30%.方法消耗试剂少,快速准确,适合烟草中多种微量元素的同时测定.