A study on the digestion of human muscle biopsies for trace metal analysis using an organic tissue solubilizer.

A commercially available tissue solubilizer, based on tetraalkyl-ammonium hydroxide in toluene, has been compared with conventional digestion producers in order to determine the minimum amount of tissue needed for the determination of trace elements such as Al, Cd, Cu, and Mn in human biopsy material using flameless atomic absorption spectrophotometry. The solubilizer can be recommended for digestion of biopsy samples in order to determine Cu, Cd, and Mn, but not Al.     

Tissue digestion for aluminum determination in experimental animal studies

Four different procedures for the determination of aluminum in tissues by atomic absorption spectrometry (AAS) were investigated. They consisted of conventional acid digestion carried out before and after sample drying, associated or not with fat extraction. Drying was carried out in a conventional oven at 65 °C for 24 h. For fat extraction, different solvents and solvent mixtures were investigated considering both extraction yield and sample adequacy for further AAS measurement. Acid digestion was carried out with pure HNO₃ or with its mixture with HClO₄. After digestion, aluminum was measured by graphite furnace atomic absorption spectrometry. Tissues were collected from Al-exposed and nonexposed mice. The results indicated that drying the sample prior to digestion is advantageous as the amount of acid necessary can be significantly reduced. This procedure does not contribute to increase the aluminum level in the samples providing that careful measures to avoid contamination are taken, as the same procedures carried out without taking any precautions to avoid contamination produced imprecise results. Finally, aluminum was not found in the fatty fraction of any sample, even in exposed mice, demonstrating that aluminum does not accumulate in this part of the tissues.     

Determination of urinary arsenic, mercury, and selenium in steel production workers

The fumes and dust of trace elements and their compounds are very toxic and have been related to an increase in the incidence of diseases. Occupational exposure to toxic metals and metalloids can be determined by means of workplace air measurements and biological monitoring. The aim of our investigation was to determine the concentrations of As, Hg, and Se in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. The method was employed for the quantitative determination of arsenic, mercury, and selenium in urine samples from steel production and quality control workers and healthy unexposed controls. After pretreatment with acids, the samples were digested by means of a microwave oven. Arsenic was determined by hydride atomic absorption spectrometry and mercury was determined by cold vapor atomic absorption spectrometry, whereas selenium was determined by a graphite furnace atomic absorption spectrometry. The results indicate those urinary arsenic, mercury, and selenium levels of the exposed workers are significantly higher than those of the controls. The possibility that these elements are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.     

Evaluation of methods for total selenium determination in yeast

The selenium determination in biological materials by the classical fluorometric method (FM) is time-consuming and also hazardous, as it requires the destruction of the organic matrix samples with hot HNO₃/HClO₄ mixtures prior to analysis. Accordingly, commercial analytical laboratories are increasingly using faster instrumental methods; for sample digestion, avoid using HClO₄. Because of these procedural changes, the results obtained by commercial laboratories may be unreliable, especially for samples containing Se in organic forms. One such “difficult” substrate is Se yeast, which contains most of its Se as selenomethionine. To establish which methods for Se analysis and sample digestion are applicable, samples of Se yeast and of selenomethionine standards were sent to laboratories employing either flame atomic absorption spectrometry (FAAS), inductively coupled plasma-mass spectrometry (ICP-MS), or hydride generation atomic absorption spectrometry (HGAAS). The result were compared with those obtained by FM and non-destructive instrumental neutron activation analysis (INAA). ICP-MS, after microwave digestion of sample with HNO₃/H₂O₂, produced results within 5% of the expected values, as did those obtained by FM and INAA. With FAAS, acceptable results were obtained after digestion with HNO₃/HCl. With HGAAS, sample digestion with HNO₃/H₂O₂ produced values that were systematically elevated by about 10% and exhibited standard deviations of ≥10%. Thus, current methods of sample digestion are applicable for Se yeast analysis by ICP-MS and FAAS, but not by HGAAS.     

A safe method to acid digest small samples of biological tissues for graphite furnace atomic absorption analysis of aluminum

A method was developed to prepare small biological tissue samples (approximately 100 mg) for flameless atomic absorption analysis of aluminum (Al). Screw cap Teflon containers were used in which the samples were dried, acid digested, acid evaporated, and diluted for analysis, minimizing contamination and sample loss. A heatable, semiclosed system was developed in which the nitric and perchloric acids used in tissue digestion could be safely evaporated from the sample containers and collected. Several spectrophotometer operating conditions for Al determination were compared, and a suitable condition was adopted. Analyses for aluminum levels in acid digested samples were conducted at two absorption wavelengths (309.3 and 396.2 nm) and by two analytical procedures (comparison of sample absorbance to standard absorbance and the method of standard additions). The developed method is suitable for analysis of the low levels of aluminum found in biological tissues and probably other elements as well. The method incorporates procedures designed to minimize contamination and the hazards of acid tissue digestion.     

Evaluation of total contents of Al,As, Ca,Cd, Fe,K, Mg,Ni, Pb,Zn and their fractions leached to the infusions of different tea samples. A multivariate study

ABSTRACT

Total aluminum, arsenic, calcium, cadmium, iron, lead, potassium, magnesium, nickel and zinc were determined in black tea by electro thermal atomic absorption spectrometry after ultrasonic assisted pseudo-digestion with mixture of acid and oxidant. All the metals were also determined in the tea infusions in order to know the percentage of each element leached into the liquor. A conventional acid digestion on electric hot plate was used to obtain total metals under study for comparative purpose. Analytical results for Al, As, Ca, Cd, Fe, K, Mg, Ni, Pb and Zn obtained by ultrasound assisted pseudodigestion, and conventional wet digestion methods showed a good agreement, thus indicating the possibility of using ultrasonic assisted digestion sample preparation instead of intensive treatments inherent with the acid digestion methods on electric hot plate. The validity and accuracy of both procedures were checked by using certified sample of NIES No. 7 (Tea Leaves). Non significant differences were observed for P>0.05 when comparing the values obtained by both methods (paired t-test).

Principal component analysis (PCA) was applied in order to determine the different amount of metals as main sources of variability in the data sets and to establish the relation between samples (branded and nonbranded tea samples) and micronutrient, trace and toxic metals (variables). Hierarchical cluster analysis (HCA) was used to explore the different branded and nonbranded tea samples grouping according to the essential and toxic metals as additional information to the out put obtained by PCA.     

微波消解－火焰原子吸收光谱法测定蜂胶中金属元素含量

目的：测定一种原产地为加拿大的蜂胶中金属元素的含量,为进一步研究蜂胶营养价值提供数据,同时改进测量方法。方法：用微波消解法处理样品,用硝酸和过氧化氢的混合物作为消解剂进行微波消解,并优化消解条件,然后用火焰原子吸收光谱法测定蜂胶制品中钙、铁、镁、锌、钠、钾、铜的含量。结果：七种元素相对标准偏差为O．85％～2．33％（n=7）,回收率在96．5％～104．7％之间。试验结果表明该蜂胶中含有丰富的金属元素,且与河南产蜂胶相比,加拿大产蜂胶中多种金属元素含量远低于河南产蜂胶。结论：使用本文方法测定蜂胶中的金属元素含量,结果准确,方法可靠。为进一步探讨蜂胶制品金属元素与其保健功能的关系提供了有用数据。     

微波消解- 火焰原子吸收光谱法测定蜂胶中金属元素含量

目的:测定一种原产地为加拿大的蜂胶中金属元素的含量,为进一步研究蜂胶营养价值提供数据,同时改进测量方法。方法:用微波消解法处理样品,用硝酸和过氧化氢的混合物作为消解剂进行微波消解,并优化消解条件,然后用火焰原子吸收光谱法测定蜂胶制品中钙、铁、镁、锌、钠、钾、铜的含量。结果:七种元素相对标准偏差为0.85%~2.33%(n=7),回收率在96.5%~104.7%之间。试验结果表明该蜂胶中含有丰富的金属元素,且与河南产蜂胶相比,加拿大产蜂胶中多种金属元素含量远低于河南产蜂胶。结论:使用本文方法测定蜂胶中的金属元素含量,结果准确,方法可靠。为进一步探讨蜂胶制品金属元素与其保健功能的关系提供了有用数据。     

Determination of trace elements in some natural drugs by atomic absorption spectrometry

Fifteen kinds of common plants, animals, and minerals used as traditional medicines by the Chinese people have been subjected to analysis by atomic absorption spectrometry for its content of seven metals: lead, cadmium, arsenic, mercury, copper, cobalt, and manganese. The concentrations of these elements are significantly different according to their vegetal, animal, or mineral origin. The average values found for lead, cadmium, arsenic, cobalt, and manganese in drugs of mineral origin are higher than those derived from plants and animals, except for copper, which was higher in drugs of animal origin. Our results suggest that the user of traditional Chinese crude drugs should be warned of the potential danger of heavy-metal poisoning because their concentrations seem to be higher than the maximum values allowed by health agencies in several countries.     

Determination of total arsenic concentrations in nails by inductively coupled plasma mass spectrometry

The analysis of trace elements in biological samples will extend our understanding of the impact that environmental exposure to these elements has on human health. Measuring arsenic content in nails has proven useful in studies evaluating the chronic body burden of arsenic. In this study, we developed methodology with inductively coupled plasma-mass spectrometry (ICP-MS) for the determination of total arsenic in nails. We assessed the utility of the washing procedures for removing surface contamination. Four types of preanalysis treatments (water bath, sonication, water bath plus sonication, and control) after sample decomposition by nitric acid were compared to evaluate the digestion efficiencies. In addition, we studied the stability of the solution over 1 wk and the effect of acidity on the arsenic signal. Arsenic content in the digested solution was analyzed by using Ar-N₂ plasma with Te as the internal standard. The results suggest that washing once with 1% Triton Χ-100 for 20 min for cleaning nail samples prior to ICP-MS analysis is satisfactory. Repeated measurement analysis of variance revealed that there was no significant difference among the various sample preparation techniques. Moreover, the measurements were reproducible within 1 wk, and acidity seemed to have no substantial influence on the arsenic signal. A limit of detection (on the basis of three times the standard deviation of the blank measurement) of 7 ng As/g toenail was achieved with this system, and arsenic recoveries from reference materials (human hair and nails) were in good agreement (95–106% recovery) with the certified/reference values of the standard reference materials. ICP-MS offers high accuracy and precision, as well as highthroughput capacity in the analysis of total arsenic in nail samples.     

Interaction Between Zinc, Cadmium, and Lead in Scalp Hair Samples of Pakistani and Irish Smokers Rheumatoid Arthritis Subjects in Relation to Controls

The incidence of rheumatoid arthritis (RA) has been associated with cigarette smoking. The aim of our study was to assess the trace essential and toxic metals, cadmium (Cd), lead (Pb), and zinc (Zn), in scalp hair samples of 32 Irish and 46 Pakistani smokers and non-smokers RA male patients with age range 42-56 years. For comparison purpose, the scalp hair samples of 27 Irish and 55 Pakistani non-RA male subjects of the same age group were collected. The concentrations of trace and toxic elements were measured by inductive coupled plasma atomic emission spectrophotometer and atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The validity and accuracy of the methodology was checked using certified reference materials and using conventional wet acid digestion method on the same certified reference materials (CRMs). The recovery of all studied elements was found to be in the range of 97.5-99.7% of certified reference values of CRMs. The results of this study showed that the mean values of Cd and Pb were significantly higher in scalp hair samples of both smoker and non-smoker RA patients than in referents (P < 0.001), whereas the concentration of Zn was lower in the scalp hair samples of smokers and non-smokers rheumatoid arthritis patients. The deficiency of Zn and the high exposure of Cd and Pb as a result of cigarette smoking may be synergistic risk factors associated with rheumatoid arthritis.     

Comparative Metal Distribution in Scalp Hair of Pakistani and Irish Referents and Hypertensive Patients

The abnormal metabolism of metal ions plays an important role in health and disease conditions, and studies about them have been attracting significant interest. The aim of our study was to assess the heavy metals (cadmium (Cd), nickel (Ni), lead (Pb), and zinc (Zn)) in scalp hair samples of 50 Irish and 78 Pakistani hypertensive patients of an urban population together with 50 Irish and 96 Pakistani non-hypertensive male subjects in the age group of 30–50 years. The concentrations of trace and toxic elements were measured by inductively coupled plasma–atomic emission spectrophotometer and atomic absorption spectrophotometer before microwave-assisted acid digestion. The validity and accuracy of the methodology were checked using certified reference materials, and by the conventional wet acid digestion method on the same certified reference materials and on real samples. The recovery of all the studied elements was found to be in the range of 97.5–99.7% in certified reference material. The results of this study showed that the mean values of cadmium, nickel, and lead were significantly higher in scalp hair samples of both Pakistani and Irish hypertensive patients than in referents (p < 0.001); whereas, the concentration of zinc was lower in the scalp hair samples of hypertensive patients of both genders. The deficiency of zinc and the high exposure of trace and toxic metals may be the risk factors associated with hypertension.     

Extraction of Arsenic and Heavy Metals from Contaminated Mine Tailings by Soil Washing

In this study, the soil washing technique has been used to treat mine tailings contaminated heavily with arsenic and heavy metals at Jingok mine, which is one of the abandoned mines in Korea. The results showed that phosphoric acid, citric acid, oxalic acid, and sodium metabisulfite were highly effective in extracting arsenic and heavy metals. Among them, oxalic acid was the most effective (especially for Pb, Cu, and Zn), as even a residual fraction of arsenic was partly extracted. The optimum concentration of washing reagent and the ratio between the mine tailings and washing reagent were found to be 0.5 M and 1:20, respectively. In addition, the extraction kinetics of arsenic and heavy metals was fast, in which the reaction time of 30 minutes was deemed to be a sufficient contact time. From the results, it may be concluded that the low pH of washing solution and the amount of dissolved Fe may be considered as the most important factors in the extraction of arsenic and heavy metals.     

Comparative Evaluation of Trace Metals in the Blood of Hepatitis C Patients and Healthy Donors

Hepatitis C is one of the common types of chronic liver disease, and its plausible association with trace metal imbalance has been investigated in the present study. The blood samples of hepatitis C patients and healthy donors were analysed for trace metals (Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, and Zn) by flame atomic absorption spectrophotometry after wet acid digestion. In the blood of the hepatitis patients, mean concentrations of essential metals, Na, K, Fe, Ca, Mg, and Zn, were 918.7, 361.0, 102.5, 20.00, 24.66, and 9.429 ppm, respectively, while the mean metal levels in the blood of healthy donors were 1509, 406.8, 232.5, 28.35, 24.59, and 8.799 ppm, respectively. On the average, Cr was significantly higher, while Na, Fe, Ca, Cu, Mn, Pb, and Cd were comparatively lower in the blood of the patients. The correlation study manifested significantly divergent mutual relationships of trace metals in the blood of the patients and healthy donors. Multivariate statistical methods revealed considerably diverse distribution of trace metals in the two groups. Dissimilarity in the trace metal distribution was also noted with the gender and residential location of the donors in both groups.     

Report on the levels of cadmium, lead, and mercury in imported rice grain samples

In an attempt to know whether highly consumed food might contribute to metal exposure, we analyzed cadmium, lead, and mercury in 27 rice grain samples commonly consumed in Saudi Arabia by atomic absorption spectrometry after acid digestion. The mean concentrations and ranges of cadmium, lead, and mercury in tested rice samples were 20.261 (range <DL-178.026 μg/kg), 134.819 (range 23.1–1529.0 μg/kg), and 3.186 (range <DL-43.573 μg/kg), respectively. The results showed high concentrations of metals and in some cases exceeded the Provisional Tolerance Weekly Intake (PTWI) recommended by FAO/WHO. It was also noted that different rice grain samples had varying concentrations of these metals. Because the bulk of literature warns against the cumulative effects of prolonged heavy metal exposure, regular consumption of rice by local populations might pose potential health problems.     

Comparison of trace heavy-metal levels from monitoring in the German Bight and the southwestern Baltic Sea

Since 1973, monitoring for selected trace heavy metals has been performed in the German Bight (North Sea) and the western Baltic Sea. This paper deals with a set of filtered and unfiltered samples from a network of 22 stations covering the whole German Bight based on a cruise with RV “Gauss” in May 1974, and a similar series of samples taken at different depths at 18 stations in the Baltic Sea in October 1974. The metals Cd, Cu, Fe, Mn, and Ni were determined by flameless atomic absorption spectrometry. Data comparison is facilitated since sampling and analytical methods were identical. Distributions of metal-content data have been calculated from unfiltered and filtered samples. Qualitative and semi-quantitative aspects of the major differences or similarities between the histograms obtained from both sea areas are discussed.     

Time course of arsenite-induced copper accumulation in rat kidney

Oral administration of inorganic arsenic has been shown to lead to an accumulation of copper in the kidneys of rats and guinea pigs. However, nothing is known about the characteristics and mechanisms of this organ-specific renal copper accumulation. Many heavy metals accumulate in the kidney, either after environmental or occupational exposure. An additional accumulation of any other trace metals, even essential ones, may therefore be critical for that organ. This prompted us to follow the course of the renal copper accumulation. Rats were given daily subcutaneous doses of sodium arsenite for 12 d. Each second day, three rats were killed by exsanguination and the liver, kidneys, and blood removed and analysed for As, Cu, and other trace elements by atomic emission spectrometry. Results indicate that arsenic and copper accumulate in the kidney cortex synchroneously over time. Arsenic also accumulated in the liver and red blood cells (RBC). Copper levels in the RBC and liver as well as copper excretion into the urine were unaffected. After terminating arsenite administration, there was a slow decline in tissue levels of both arsenic and copper, a phenomenon which was parallel for both metals. Because the copper level in the liver was not affected, it is concluded from this study that renal processes and not hepatic or biliary mechanisms might be responsible for the renal copper accumulation. Furthermore, the strong linear correlation (r=0.85) between arsenic and copper levels in the kidney during and after arsenite administration suggests a functional relationship between arsenic and copper with respect to their retention in the kidney.     

Evaluation of Status of Trace and Toxic Metals in Biological Samples (Scalp Hair, Blood, and Urine) of Normal and Anemic Children of Two Age Groups

Anemia affects a substantial portion of the world’s population, provoking severe health problems as well as important economic losses to the region in which this condition is found. This study was designed to compare the levels of essential trace and toxic elements in scalp hair, blood, and urine samples of anemic children (n = 132) with age range 1–5 and 6–10 years of both genders. For a comparative study, 134 non-anemic age- and sex-matched children as control subjects, residing in the same city, were selected. The metals in the biological samples were measured by flame atomic absorption spectrophotometry/electrothermal atomic absorption spectrometry prior to microwave-assisted acid digestion. The proposed method was validated using certified reference samples of hair, blood, and urine. The results indicated significantly lower levels of iron, copper, and zinc in the biological samples as compared to the control children of both genders (p = 0.01–0.008). The mean values of lead and cadmium were significantly high in all three biological samples of anemic children as compared to non-anemic children of both age groups (p = 0.005–0.001). The ratios of essential metal to toxic metals in the biological samples of anemic children of both age groups were significantly lower than that of controls. Deficiency of essential trace metals and high level of toxic metals may play a role in the development of anemia in the subjects under study.     

Direct and rapid determination of ultratrace heavy metals in solid plant materials by ET‐AAS ultrasonic‐assisted slurry sampling

Introduction – Plants can be used as bioindicators in the study of contamination processes by heavy metals. Most of the analytical methodologies used for determination of metals in plants are based on atomic techniques with previous wet digestion of the solid samples. Methodologies that allow direct metal measurements in solid samples are very attractive alternatives. Objective – To develop a new procedure for direct analysis of copper, nickel, cadmium and lead at very low concentration levels in leaves based on electrothermal atomic absorption spectroscopy (ET‐AAS) with introduction of samples as a slurry. Methodology – In order to obtain accurate and precise results even at very low concentrations, the different parameters that influence the sample slurry preparation such as acid percentage, presence of stabilising agents and ultrasonic probe operation were studied. Instrumental parameters such as chemical modifier and temperature and times for drying, pyrolysis and atomisation steps that influence ET‐AAS measurement were optimised. Results – Optimal slurry conditions for copper and nickel determination were 0.5% Tween 85 with 5% nitric acid. For lead and cadmium analysis the best results were obtained in 5% nitric acid without stabilising agents. The achieved detection limits were 0.023 mg/kg for copper, 0.018 mg/kg for nickel, 0.0002 mg/kg for cadmium and 0.009 mg/kg for lead. For validation purposes, the method was applied to metal analysis in a pine needles reference material. Conclusion – According to our knowledge, the detection limits obtained are the best reported in the literature. The methodology was successfully used in metal determinations in actual leaf samples. Copyright © 2010 John Wiley & Sons, Ltd.     

Evaluation of Status of Cadmium, Lead, and Nickel Levels in Biological Samples of Normal and Night Blindness Children of Age Groups 3–7 and 8–12 Years

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood trace metals toxicity, which is the most common problem found in underdeveloped countries. This study was designed to compare the levels of cadmium (Cd), lead (Pb), and nickel (Ni) in scalp hair, blood, and urine of night blindness children age ranged 3–7 and 8–12 years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of Cd, Pb, and Ni in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cd, Pb, and Ni by electrothermal atomic absorption spectrometry. The results indicated significantly higher levels of Cd, Pb, and Ni in the biological samples (blood, scalp hair, and urine) of male and female night blindness children, compared with control subjects of both genders. These data present guidance to clinicians and other professional investigating toxicity of trace metals in biological samples of night blindness children.