Microwave-assisted acid extraction methodology for trace elements determination in mastic gum of Pistacia lentiscus using inductively coupled plasma atomic emission spectrometry

Introduction – To ensure food safety, accurate knowledge of the levels of several trace elements is necessary. This is also true for natural products of plants and resins used for human consumption or therapeutic treatment, like the mastic gum of Pistacia lentiscus. The rapid analysis of gum and resin matrices is a challenge because there are problems with the decomposition of such complicated matrices. Objective – To develop an efficient multielemental analytical method for the determination of trace elements and to compare different procedures for analyte extraction when microwave‐assisted digestion is applied. Methodology – The inductively coupled plasma atomic emission spectrometric (ICP‐AES) technique was applied and the optimum ICP conditions like radiofrequency power, argon flow rate and nebuliser sample uptake flowrate were found. The microwave‐assisted procedure was compared with that with conventional heating. Since mastic and resinous materials are difficult for dissolution and extraction of trace element, influential acid mixtures containing hydrofluoric acid proved to be capable of quantitative extraction of the analytes. Results – The digestion of mastic resin or similar matrices is significantly facilitated by using microwave radiation instead of conventional heating since the obtained recovery for several analytes is much higher. It was proved that the acid mixture of HCl–HNO₃–HF was the most efficient for complete sample digestion and recovery of the analytes. Conclusions The performance characteristics of the developed method were evaluated against certified reference material and the method was proved reliable and applicable to the analysis of mastic gum and possibly to similar resinous matrices. Copyright © 2010 John Wiley & Sons, Ltd.     

Multi-element analysis of trace element levels in human autopsy tissues by using inductively coupled atomic emission spectrometry technique (ICP-AES).

Autopsy tissue samples from the brain front lobe, cerebellum, heart, kidney (cortex and medulla), liver, pancreas, spleen and ovary were analysed for AL, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, Sr and Zn in 30 (17 women and 13 men) subjects ranging in age from 17 to 96 years at Haukeland University Hospital in Norway. The tissues were selected from macroscopically normal organs and samples were handled according to guidelines recommended to avoid contamination in the pre-analytical phase. Concentration of the trace elements were determined by the inductively coupled plasma atomic emission spectrometry technique (ICP-AES). In most tissues the concentrations of the essential trace elements followed the order Fe> Zn> Cu> Mn> Se> Cr> Co except in the ovary where Se was higher than Mn. The liver was the major site of deposition for Co, Cu and Mn as well as the spleen for Co, brain front lobe for Cu and pancreas for Mn. Ba, Sr and Ni built up in the ovary foLLowed by the kidney. Older subjects accumulated Ba and Sr in most tissues, whereas Al accumulated in the kidney cortex and Cd in the brain cerebellum. Generally males had higher concentrations of trace elements in the different tissue sampLes than females with the exception of Mn in the brain front lobe and heart and Sr in the liver. ICP-AES is a useful method to assess the concentration and the profiLe of trace elements in human autopsy tissues.     

Multianalysis of trace elements in mosses with inductively coupled plasma-mass spectrometry

As a part of an air-pollution biomonitoring survey, a procedure using inductively coupled plasma-mass spectrometry (ICP-MS) and microwave digestion was developed to achieve a high sample throughput and guarantee the accuracy of the results. This article presents an analytical method to measure 22 trace elements. As, Ba, Cd, Ce, Co, Cr, Cs, Cu, Fe, Hg, La, Mo, Ni, Pb, Rb, Sb, Sr, Th, Tl, U, V, W were analyzed in 563 mosses collected in France. The digestion was performed in polytetrafluoroethylene (PTFE) vessel using the mixture HNO₃-H₂O₂-HF. The data were reprocessed taking into account the drift curve calculated for each element. The detection limits (DL) calculation was based on the standard deviations of the reagent blanks concentrations. The DL varied from one batch to another, because of the heterogeneity of the mosses’ elemental contents. The DL ranged between 0.001 μg/g (Cs, Tl) and 70 μg/g (Fe) and were mainly around 0.01 μg/g (As, Cd, Ce, Co, Hg, La, Mo, Sb, Sr, U, V, W). The detection limits obtained were in agreement with the concentrations observed in the samples, except for Hg and Ni. The reproducibility between duplicates and the analytical precision were near 10%. The procedure was tested with the mosses’ reference materials.     

Comparisons between the inorganic content of healthy and hypertensive rat tissues by inductively coupled plasma-mass spectrometry

The inorganic contents of bone, brain, erythrocyte, heart, kidney cortex, kidney medulla, liver, lung, muscle and plasma from spontaneously hypertensive rats were compared with those of the same tissues from healthy Sprague-Dawley rats. A general inductively coupled plasma-mass spectrometry method developed for multi-element determinations of most of the elements present in biological tissues was used. Variations were found not only for major elements, as expected, but also for many trace elements in several tissues.     

Application of inductively coupled plasma sector field mass spectrometry for elemental analysis of urine

An analytical method using double focusing sector field inductively — coupled plasma mass spectrometry (sector field ICPMS) for rapid simultaneous determination of 42 elements in urine is described. Sample preparation consisted of 20-fold dilution with 0.14 mol/l nitric acid in ultrapure water. The importance of controlling possible contamination sources at different sample preparation and analysis stages in order to achieve adequate method detection limits (DL) is emphasized. Correction for matrix effects was made using indium and lutetium as internal standards. Different approaches for accuracy assessment in urine analysis are evaluated. Additional information on trace element concentrations in a urine reference material is given. Between-batch precision was assessed from the analysis of separately prepared aliquots of the reference material and was better than 10% RSD for 32 of the elements. The robustness of the procedure was tested by analysis of about 250 samples in one analytical run lasting more than 50 hours. A statistical summary of results for 19 urine samples from non-exposed subjects is presented. For a majority of the elements tested concentrations were higher than the detection limit of the method.     

Matrix interferences in the analysis of digested biological tissues with inductively coupled plasma-mass spectrometry

To investigate the physiological roles or toxicity of trace or toxic elements, multielement analysis of limited quantities of samples in the biological tissues is required. Inductively coupled plasma mass spectrometry (ICP-MS) suits this requirement, but spectral and nonspectral interferences are inevitable. We examined correction methods for the nonspectral interferences by analyzing signals of 21 elements in various concentrations of HNO₃ as well as five major elements (Na, K, P, Ca, and Cl). Using internal standards, the interferences caused by the major elements were corrected, but the interferences caused by HNO₃ were impossible to correct for elements with high ionization potentials. The analytical results using the standard addition method on 14 elements in standard reference materials and fresh brain tissues confirmed the accuracy of this method. Thus, we concluded that the standard addition method is useful to correct for the nonspectral interferences.     

Concentrations of selected trace elements in human milk and in infant formulas determined by magnetic sector field inductively coupled plasma-mass spectrometry

Magnetic sector field inductively coupled plasma-mass spectrometry (ICP-MS) was applied to the reliable determination of the 8 essential trace elements cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), selenium (Se), and vanadium (V) as well as the 7 nonessential and toxic elements silver (Ag), aluminum (Al), arsenic (As), gold (Au), platinum (Pt), scandium (Sc), and titanum (Ti) in 27 transitory and mature human milk samples and in 4 selected infant formulas. This advanced instrumentation can separate spectral overlaps from the analyte signal hampering significantly the determination of many trace elements by conventional ICP-MS. Moreover, superior detection limits in the picogram per liter range can be obtained with such magnetic sector field instruments. Therefore, this is the first study to report the concentrations of the elements Ag, Au, Pt, Sc, Ti, and V in human milk and in infant formulas. Concentrations of Ag (median: 0.41 μg/L; range: <0.13–42 μg/L) and Au (median: 0.29 μg/L; range 0.10–2.06 μg/L) showed large variations in human milk that might be associated with dental fillings and jewelry. Pt concentrations were very low with most of the samples below the method detection limit of 0.01 μg/L. Human milk concentrations of Co (median: 0.19 μg/L), Fe (380 μg/L), Mn (6.3 μg/L), Ni (0.79 μg/L), and Se (17 μg/L) were at the low end of the corresponding reference ranges. Concentrations of Cr (24.3 μg/L) in human milk were five times higher than the high end of the reference range. For Al (67 μg/L), As (6.7 μg/L), and V (0.18 μg/L), most of the samples had concentrations well within the reference ranges. All elemental concentrations in infant formulas (except for Cr) were approximately one order of magnitude higher than in human milk.     

Rapid metal speciation of cell culture media using reversed-phase separations and inductively coupled plasma optical emission spectrometry

Cell culture media metal content is critical in mammalian cell growth and monoclonal antibody productivity. The variability in metal concentrations has multiple sources of origin. As such, there is a need to analyze media before, during, and after production. Furthermore, it is not the simple presence of a given metal that can impact processes, but also their chemical form that is, speciation. To a first approximation, it is instructive to simply and quickly ascertain if the metals exist as inorganic (free metal) ions or are part of an organometallic complex (ligated). Here we present a simple workflow involving the capture of ligated metals on a fiber stationary phase with passage of the free ions to an inductively coupled plasma optical emission spectrometry for quantification; the captured species are subsequently eluted for quantification. This first level of speciation (free vs. ligated) can be informative towards sources of contaminant metal species and means to assess bioreactor processes.     

Laser ablation inductively coupled plasma mass spectrometry imaging of metals in experimental and clinical Wilson's disease

Wilson's disease is an autosomal recessive disorder in which the liver does not properly release copper into bile, resulting in prominent copper accumulation in various tissues. Affected patients suffer from hepatic disorders and severe neurological defects. Experimental studies in mutant mice in which the copper‐transporting ATPase gene (Atp7b) is disrupted revealed a drastic, time‐dependent accumulation of hepatic copper that is accompanied by formation of regenerative nodes resembling cirrhosis. Therefore, these mice represent an excellent exploratory model for Wilson's disease. However, the precise time course in hepatic copper accumulation and its impact on other trace metals within the liver is yet poorly understood. We have recently established novel laser ablation inductively coupled plasma mass spectrometry protocols allowing quantitative metal imaging in human and murine liver tissue with high sensitivity, spatial resolution, specificity and quantification ability. By use of these techniques, we here aimed to comparatively analyse hepatic metal content in wild‐type and Atp7b deficient mice during ageing. We demonstrate that the age‐dependent accumulation of hepatic copper is strictly associated with a simultaneous increase in iron and zinc, while the intrahepatic concentration and distribution of other metals or metalloids is not affected. The same findings were obtained in well‐defined human liver samples that were obtained from patients suffering from Wilson's disease. We conclude that in Wilson's disease the imbalances of hepatic copper during ageing are closely correlated with alterations in intrahepatic iron and zinc content.     

Determination of trace elements in porcine brain by inductively coupled plasma-mass spectrometry,electrothermal atomic absorption spectrometry,and instrumental neutron activation analysis

Methods have been developed for the analyses of trace metals in various areas of porcine brains, (temporal, parietal, frontal cortex, both right and left hemispheres). Determinations were carried out using inductively coupled plasma-mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS). The elements investigated were Li, Mn, Cu, Zn, Cd, Hg, and Pb by ICP-MS and Cu, Cd, and Mn by ETAAS. For determination by ICP-MS, a method of standard additions calibration coupled with internal standards was used, and for ETAAS, standard additions calibrations were prepared. The accuracy of all methods was determined using NIST and IAEA certified reference material. A small number of pig brains were analyzed by instrumental neutron activation analysis for Cr, Co, Cs, Fe, Rb, Se, Sc, Sb, and Zn using the comparator method of analysis. Four separate NIST standard reference materials have been used to examine the validity of the comparator method.     

A fast method for multi-metal determination in soil samples by high-resolution inductively-coupled plasma-mass spectrometry (HR–ICP–MS)

Abstract

Methods for multi-elemental quantitative analysis of soil samples by high-resolution inductively-coupled plasma-mass spectrometry (HR–ICP–MS) with preceding one-step wet digestion in a high-pressure microwave system have been developed. The application of aqua regia as a reagent for wet digestion using a high-pressure microwave digestion system, followed by determination using HR–ICP–MS, allows an accurate, simultaneous determination of a large number of heavy metals and metalloids that are considered as potentially hazardous for the environment and health. The values of the concentrations of the elements in the analysed certified reference material (CRM) that have been obtained in this study can be used as indicative values where this CRM is used as a control for the quality of the measurements.     

Density gradient separation of carborane-containing liposome from low density lipoprotein and detection by inductively coupled plasma spectrometry

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used for analyzing the new cholesterol-based compounds (BCH, BCH-Da, BCH-Db and BCH-Dc) in liposomal formulations. Not only the boron compounds but also the phospholipid compositions of the liposome formulation were quantitatively analyzed. Reasonable limit of detection for boron (0.5?µg/ml) and phosphorous (0.09?µg/ml), respectively, was observed. ICP-MS was also utilized for analyzing BCH in a brain distribution study. The detection limit of boron analysis by ICP-MS is at least three orders of magnitude lower than of that of ICP-AES (1?ng B/ml). The method was linear in the range of 500-1?ng B/ml and the linearity correlation coefficient was 1. In addition, an ultracentrifugation method was developed to separate liposomes from low-density lipoprotein (LDL). Factors such as density gradient and size of liposomes were adjusted to optimize separation and it was observed that in conjunction to time, speed and density gradient, size of the liposome also had impact on the separation using centrifugation method. These findings show the importance of ICP-AES as an analytical method for the analysis of element-based compounds encapsulated in phospholipid vesicles.     

Nutritional and toxic elemental analysis of dry fruits using laser induced breakdown spectroscopy (LIBS) and inductively coupled plasma atomic emission spectrometry (ICP-AES)

Quantitative investigation of essential and trace heavy elements present in health-beneficial dry fruits (Pistachio, Almonds, Black walnut, White walnut, and Cashew) was investigated using Laser Induced Breakdown Spectroscopy. For an accurate elemental exposure using LIBS technique, the local thermo-dynamical equilibrium of the laser induced plasma was established and verified using McWhirter criterion based on the electron number density in the plasma. Earlier to engage, our LIBS detector was optimized. For quantification of elements, standard calibration curves (CC)-LIBS method was applied. Using our LIBS system, the nutritional elements such as Al, Mg, Ca, Fe, K, Zn, and Na and toxins like Pb, Cr, and Cu were detected in dry fruits. The elemental quantification of dry fruit contents were validated using standard (ICP-AES) method and the relative accuracy of our experimental setup in comparison to ICP approach was in the ranging from 0.1 to 0.3 at 2.5-% error confidence.     

Rapid and direct determination of selenium, copper, and zinc in blood plasma by flow injection-inductively coupled plasma-mass spectrometry

A flow injection-inductively coupled plasma-mass spectrometry (FI-ICP-MS) with a simple sample preparation procedure was developed for the determination of selenium, copper, and zinc in blood serum/plasma. A serum/plasma sample was filtered through a 0.45-μm membrane filter and diluted with a mixture of trace elements in a standard solution (9∶1, v/v). Measurement of the reference serum sample confirmed the accuracy of our method for selenium, copper, and zinc concentration. In the case of blood plasma samples obtained from six healthy adult males, the selenium, copper, and zinc concentrations were similar to those of a typical healthy male in Japan. These results suggest that the sample prepartive procedure coupled with FI-ICP-MS can be used for the routine determination of selenium, copper, and zinc in human blood serum/plasma.     

Multielement analysis of biological samples by inductively coupled plasma-mass spectrometry

Interest in the biological behavior of a growing number of elements, along with increasing recognition of the importance of interactions among them, demands a versatile and reliable technique for multielement analysis of biological samples. Significant improvements over the sensitivity achieved with conventional inductively coupled plasma (ICP) optical emission spectrometries have been realized with the introduction of quadrupole mass spectrometry (MS) for detection of ions in the plasma. The hybrid technique of ICP-MS promises to be a method of rapid multielement analysis, at detection limits that approach or surpass those of other technologies. However, the application of ICP-MS to analyses of biological interest is truly in its infancy. Here we report the use of ICP-MS for the determination of more than 30 elements of biological interest in a tissue and a biological fluid (rat liver and serum, respectively). Experimental values of the elements serve as a basis for discussion of analytical protocols, performance criteria, and certain problems peculiar to ICP-MS.     

微波程序消解-ICP-AES测定栾果与黄山栾果中14种元素

为了探讨栾果与黄山栾果中微量元素含量及其分布特性,充分开发和利用该天然资源,采用微波程序消解-ICP-AES法同时测定栾果与黄山栾果中的14种元素。结果表明:栾果与黄山栾果中的P、Ca和Mg含量较高,不同元素在果中各组织的分布不同,果肉中的P和Mg含量超过果皮的2倍以上,果皮中的Al、Ca、Na、Ti和Zn明显高于果肉,Fe明显低于果肉,Cr、Mn和K在果皮、果肉和全果中的分布较为均匀,而限量元素Cr和Se的含量未超出国家标准。该法快速灵敏、操作简便,用于栾果中14种微量元素的同时测定,结果令人满意。     

Speciation of trace elements in proteins in human and bovine serum by size exclusion chromatography and inductively coupled plasma-mass spectrometry with a magnetic sector mass spectrometer

 Proteins are separated by size exclusion chromatography while atomic ions from the inorganic elements are detected on-line by inductively coupled plasma-mass spectrometry. A double focusing mass analyzer provides very high sensitivity, low background, and sufficient spectral resolution to separate the atomic ions of interest from most polyatomic ions at the same nominal m/z value. The chromatograms show the distribution of the elements of interest between protein-bound and free fractions and provide the approximate molecular weights of those protein fractions that contain the elements monitored. The distribution of various elements, including V, Mo, Fe, Co, Mn, and lanthanides, in human or bovine serum samples are shown. Alkali metals and Tl are present primarily as free metal ions and are not bound to proteins. Inorganic elements spiked into the serum samples can be followed into various proteins. EDTA does not remove Fe, Pb, Sn, or Th from the proteins but does extract Mn from some proteins. Procedures for determining the effects of breaking disulfide linkages on the metal binding characteristics of proteins are also described. Received: 22 March 1999 / Accepted: 16 June 1999     

Polyatomics in zinc isotope ratio analysis of plasma samples by inductively coupled plasma-mass spectrometry and applicability of nonextracted samples for zinc kinetics

Inductively coupled plasma-mass spectrometry (ICP-MS) is a powerful tool for both quantitative multielement analyses of inorganic elements and measurement of isotope ratios (IRs). The main disadvantage of this technique is the existence of polyatomic isobaric interferences at some key masses. Zinc has been investigated for such potential interferences in serum or plasma. The Zn isotopes,⁶⁶Zn and⁶⁸Zn, have no apparent interferences, but³²S¹⁶O₂ and³²S₂ are isobaric with⁶⁴Zn. The possible effects of S and other major components of blood plasma—Na, K, Cl, P, Ca—on Zn IRs were investigated using a series of mineral solutions which simulated human plasma with respect to these elements. The mixture of all mineral elements interfered only with⁶⁴Zn (6.66 ng/mL) and⁷⁰Zn (8.51 ng/mL). Interferences to⁶⁶Zn,⁶⁷Zn, and⁶⁸Zn were minimal containing 0.90, 0.94, and 0.39 ng/mL, respectively. The copresence of Na or S shifted³⁵Cl¹⁶O₂ (atomic mass 67 coming from Cl solution) to³⁵Cl₂ which reduced the contribution to⁶⁷Zn. The hypothesis that Zn IRs obtained from plasma at various intervals after the intravenous administration of enriched⁶⁷Zn to humans would reflect those obtained after extraction of Zn was therefore tested. To compare the two pretreatment methods, “extraction” versus “nonextraction,” specimens were collected from 10 human subjects at intervals of 5 min to 24 h postinjection, and in 4 subjects from 5 min to 9 d postinjection. Two separate aliquots of plasma from each time-point were dried and digested with hydrogen peroxide, and the residue dissolved in nitric acid. One specimen was subjected to zinc extraction using ammonium diethyldithiocarbamate chelate followed by back extraction into nitric acid. The matching aliquot received no further pretreatment. The normalized IRs obtained from⁶⁷Zn/⁶⁶Zn and⁶⁷Zn/⁶⁸Zn in both the “extracted” and “nonextracted” samples agreed well(r ² = 0.976 andr ² = 0.985, respectively) compared to those from other ratios (r ² = 0.838 for⁶⁷Zn/⁶⁴Zn andr ² = 0.747 for⁶⁷Zn/⁷⁰Zn). Considering the minimum possibility of isobaric interferences in plasma samples,⁶⁷Zn/⁶⁸Zn obtained from “nonextracted” samples is sufficient for routine Zn kinetic analysis by ICP-MS.     

ICP-MS法测定广西金樱根及炮制品中22种金属元素

为建立广西金樱根药材中22种金属元素的电感耦合等离子体质谱(ICP-MS)分析方法,该文对不同产地药材及其炮制品中金属元素含量进行比较分析,评价其药材的质量和优选适当的炮制方法.同时,采用ICP-MS法测定22种金属元素含量,绘制其特征金属元素柱状图谱,并采用系统聚类分析和主成分分析对金樱根药材不同产地、不同炮制品的4...