Fractionation of potentially toxic elements in urban soils from five European cities by means of a harmonised sequential extraction procedure

The revised (four-step) BCR sequential extraction procedure has been applied to fractionate the chromium, copper, iron, manganese, nickel, lead and zinc contents in urban soil samples from public-access areas in five European cities. A preliminary inter-laboratory comparison was conducted and showed that data obtained by different laboratories participating in the study were sufficiently harmonious for comparisons to be made between cities and land types (e.g. parks, roadside, riverbanks, etc.). Analyte recoveries by sequential extraction, with respect to direct aqua regia digestion, were generally acceptable (100 ± 15%). Iron, nickel and, at most sites, chromium were found mainly in association with the residual phase of the soil matrix. Copper was present in the reducible, oxidisable and residual fractions, whilst zinc was found in all four sequential extracts. Manganese was strongly associated with reducible material as, in some cities, was lead. This is of concern because high lead concentrations were present in some soils (>500 mg kg⁻¹) and the potential exists for remobilisation under reducing conditions. As would be expected, extractable metal contents were generally highest in older, more heavily industrialised cities. Copper, lead and zinc showed marked (and often correlated) variations in concentrations between sites within the same city whereas manganese and, especially, iron, did not. No overall relationships were, however, found between analyte concentrations and land use, nor between analyte partitioning and land use.     

Determination and assessment of the contents of essential and potentially toxic elements in Ayurvedic medicine formulations by inductively coupled plasma-optical emission spectrometry

Traditional Ayurvedic remedies are easily available nowadays not only in India, their country of origin, but also in Western countries. Some of these products contain high concentrations of potentially toxic elements as main or secondary ingredients, in addition to elements essential for human health; for these reasons, it is interesting to determine their elemental composition. In this study we assessed the concentrations of fifteen elements (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Pb, Si and Zn) in five products of the Parpati family, a group of Ayurvedic medicines containing high concentrations of mercury, manufactured in various places in India. Concentrations were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) or (for Pb and Cd) by graphite furnace atomic absorption spectrometry (GF-AAS) after sample mineralization. We compared the calculated daily intake of each element with reference values, considering maximum tolerable intake levels or recommended nutrient amounts. The experimental results were treated with chemometric pattern recognition techniques. We found differences in the composition of products of the same denomination manufactured by different companies and strong correlations among groups of variables. As expected, the daily intake of mercury upon consumption of Parpati medicines largely exceeded the tolerable intake level of this element.     

The optimization of microwave digestion procedures and application to an evaluation of potentially toxic element contamination on a former industrial site

The optimization of a microwave dissolution procedure for potentially toxic elements in a contaminated soil sample has been evaluated using a central composite design approach. By considering the operating parameters of temperature, digestion time, microwave power and acid volume it was possible to identify the following optimum conditions: temperature, 160 °C; power, 750 W; digestion time, 25 min; and, an aqua regia volume of 13 mL. These microwave digestion conditions were then applied to 19 samples obtained from a former industrial site in Newcastle upon Tyne. Of the range of potentially toxic elements present at the site as a consequence of former industrial activity (As, Cd, Cr, Cu, Mo, Ni, Pb and Zn), the majority of topsoil samples indicated elevated concentrations of one or more of these elements. In particular, data obtained using either inductively coupled plasma mass spectrometry or flame atomic absorption spectroscopy indicates the high and wide concentration of Pb on the site (188-60300 mg/kg). Comparing the resulting potentially toxic elements data with UK soil guidelines values (SGVs) suggests at least parts of the site represent areas of potential human health risk. It was found that lead soil values exceeded the SGV on 17 out of the 19 sampling sites; similarly for As 6 out of 19 sampling sites exceeded the SGV. While for Cd, Cr and Ni the soil levels were below the stated SGVs.     

The importance of precision in sampling sludges, biowastes and treated soils in a regulatory framework

As part of the European Commission (EC)'s revision of the Sewage Sludge Directive and the development of a Biowaste Directive, there was recognition of the difficulty of comparing data from Member States (MSs) because of differences in sampling and analytical procedures. The ‘HORIZONTAL' initiative, funded by the EC and MSs, seeks to address these differences in approach and to produce standardised procedures in the form of CEN standards. This article is a preliminary investigation into aspects of the sampling of biosolids, composts and soils to which there is a history of biosolid application. The article provides information on the measurement uncertainty associated with sampling from heaps, large bags and pipes and soils in the landscape under a limited set of conditions, using sampling approaches in space and time and sample numbers based on procedures widely used in the relevant industries and when sampling similar materials.These preliminary results suggest that considerably more information is required before the appropriate sample design, optimum number of samples, number of samples comprising a composite, and temporal and spatial frequency of sampling might be recommended to achieve consistent results of a high level of precision and confidence.     

Biotransformation fate and sustainable mitigation of a potentially toxic element of mercury from environmental matrices

The deposition of potentially toxic mercury (Hg) in various ecosystems and subsequent entry into the food chain pose serious concerns to the ecosystem, biodiversity, and public health. In terms of toxicity, Hg is considered as a neurotoxin and capable to augment in food chains and bind to the thiol functional entity in living tissue. Moreover, methylated mercury (CH₃Hg⁺) is a highly toxic form of mercury and extremely difficult to remove from living bodies. Mercury methylation is mainly conducted by microbial and/or chemical processes under appropriate conditions. The mechanisms associated with mercury methylation inside the environment, their sources, production/degradation rate, and transport into the living organisms are not well understood. In addition, efficient and sustainable remediation strategies are essential to employ for mercury removal. Therefore, this review signifies a possible mechanism for mercury methylation and its transportation in the environment, including molecular mechanisms and genes associated with microbial-mediated mercury methylation, and identifies the gaps in existing research. The transport of Hg into the human body and associated health risks are given with suitable examples. Moreover, the escalating anthropogenic activities, the rate-limiting factors, and the sustainable remediation strategies implemented for mercury removal from the environment are discussed. This study will provide a scientific base, direction, and progress in future studies.     

Determination of non-toxic and potentially toxic elements concentration and antioxidant capacity in selected natural and essential oils with high market values

Natural oils (NOs) and essential oils (EOs) are widely used in the food and beverage, medical, aromatherapy and cosmetic industries, but little is known about their elemental composition or antioxidant ability. Microwave-assisted acid digestion and inductively coupled plasma-optical emission spectroscopy were used to determine the non-toxic elements (Al, Ca, Cu, Fe, K, Mg, Na, Se and Zn) and potentially toxic elements (As, Cr, Cd, Mn, Ni and Pb) concentrations in 13 selected NOs and EOs. The per cent recoveries of laboratory-fortified blanks analysed for quality control were 94–110%. The elemental concentrations varied widely in NO and EO samples, as demonstrated by the large standard deviation obtained for some elements. The average levels of non-toxic elements (Al (14.5 ± 3.7 μg/g); Ca (278 ± 138 μg/g); Cu (7 ± 14 μg/g); Fe (16 ± 5 μg/g); K (36 ± 31 μg/g); Mg (56 ± 27 μg/g); Na (266 ± 277 μg/g); Se (0.7 ± 0.3 μg/g) and Zn (6.1 ± 2.6 μg/g)) were determined in NOs and EOs. Comparatively, low levels of potentially toxic elements (As (0.1 ± 0.2 μg/g); Cd (0.1 ± 0.0 μg/g); Cr (0.2 ± 0.1 μg/g); Mn (0.8 ± 0.1 μg/g); Ni (4.5 ± 2.2 μg/g); and Pb (0.3 ± 0.2 μg/g)) were obtained in the oils. Principal component analysis (PCA) revealed that the first two principal components explained 100% of the variability in the elemental concentrations. Na, Ca, Mg and K were the main contributors to PCA. Non-toxic element pairs were strongly correlated (R² > 0.9440) indicating a common source in these oils, but toxic element pairs were poorly correlated. Although toxic element concentrations were low, routine monitoring in oils is recommended. The antioxidant ability of NOs and EOs to potentially reduce free radicals, which are often involved in several degenerative diseases, such as ageing, stroke, diabetes and cancers was determined by DPPH (2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl) free radical scavenging assay and ultraviolet-visible spectroscopy. Jasmine, castor and tea tree lemon oils were the best antioxidants. The oils in this study have the potential to replace artificial antioxidants used in foods, cosmetics and other products.     

CCD-ICP-AES内标法同时测定化肥中12种有害元素

研究了采用CCD-ICP-AES同时测定化肥中As、Cd、Co、Cr、Cu、Hg、Mo、Ni、Pb、Sb、Se和Zn等12种有害元素的方法.采用微波消解法处理样品,加入Y作为内标,消除了化肥基体对测定结果的干扰效应.方法对化肥中各元素的测定回收率在81.6%～120%之间,测定精密度在0.7%～13.8%之间.用该法测定了两种国家标准物质.     

Interactive effects of age and gender on levels of toxic and potentially toxic metals in children hair in different urban environments

Children growth and development may be affected by metal exposure. The objective of the present study was to investigate the interactive effects of age and gender on children hair toxic metal levels in urban environment of two Russian cities. A total of 2021 children living in Moscow and Novosibirsk aged 1–18 years old were examined. Hair Al, As, Cd, Hg, Ni, Pb and Sn levels were assessed using inductively-coupled plasma mass-spectrometry in dynamic reaction cell mode. Children from Novosibirsk were characterised by higher hair Al (37%), As (385%), Cd (127%), Hg (11%), Ni (23%), Pb (72%) and Sn (25%) in comparison to Moscow values. In the general cohort, boys had higher Al (13%), As (51%), Cd (65%), Pb (63%) and Sn (18%) levels, whereas hair Ni was higher in girls (17%). Further analysis demonstrated age-specific gender differences. In particular, only hair Ni and Cd levels were higher in male toddlers and pre-schoolers from Novosibirsk as compared to females. No gender difference was detected in Moscow. Maximal gender differences in hair metal levels were detected in adolescents for both locations. International Union of Pure and Applied Chemistry (IUPAC) reference values for all groups were also calculated. The overall reference limits for the studied children population were Al (1.335–3.340 µg/g), As (0.021–0.384 µg/g), Cd (0.000–1.389 µg/g), Hg (0.024–0.722 µg/g), Ni (0.076–0.701 µg/g), Pb (0.050–1.490 µg/g) and Sn (0.070–1.026 µg/g). Two-way ANOVA demonstrated significant effects of age, gender and age*gender interaction on hair metals in both cities. At the same time, the age-specific changes in hair metal content were more expressed in children from Novosibirsk, being exposed to higher metal pollution. The obtained data demonstrate that age, gender as well as the particular rate of pollution in each location should be taken into account during interpretation of hair test results.     

Method validation for direct determination of some trace and toxic elements in soft drinks by inductively coupled plasma mass spectrometry

The consumption of soft drink beverages has increased in the last few years around the world and it is related to the diversity of brands and flavours available, increasing also the risk of ingestion of compounds considered non-beneficial to the health of consumers. In this study, fast, easy and simple method of analysis for direct determination of As, Pb, Cd, Sb, Hg, Cu, Zn, Fe, Al, Cr, Sn, Co, Mn and Ni in soft drink samples using quadrupole inductively coupled plasma mass spectrometry (Q-ICP–MS) was validated. The estimated detection limits, practical quantification limits, linearity (linear dynamic ranges and method linearity), accuracy (trueness and precision) and measurement uncertainty parameters were studied under optimised (Q-ICP–MS) conditions. The method showed that the estimated detection limits were varied between 0.02 and 2.403 µg/L, and the quantification limits were varied between 0.5 and 20 µg/L. The mean recoveries ± standard deviations at different spiking levels were varied between 75.03 ± 0.62% and 117.07 ± 2.83% and the coefficients of variation were varied between 0.49% and 9.79%. The method trueness was confirmed by using four different certified reference materials (soft drinks and treated water) purchased from FAPAS (Food Analysis Performance Assessment Scheme) and all obtained results were within satisfactory ranges and had acceptable recovery and Z-score values. The method precision, in terms of relative standard deviation, was below 4.88%. The method uncertainty expressed as expanded uncertainty of all validated elements was found to be ≤22.52%. The results obtained make the method suitable for accurate determination of validated elements in different kinds of soft drink samples at these low concentration values. Validated method was used for the determination of metallic contaminants in 40 commercial soft drink samples and the results were compared with the provisional guideline of the elements stated by Egyptian, WHO and European standards in drinking and potable bottled natural mineral water.     

Ultrasound-assisted sequential extraction method for the evaluation of mobility of toxic elements in contaminated soils

A method for the fast sequential extraction of toxic elements in contaminated soil samples using an ultrasonic water bath, followed by determination with inductively coupled plasma optical emission spectrometry (ICP-OES), was developed and compared with other methods introduced in the literature. The five-step sequential extraction (Tessier scheme) was shortened using ultrasound-assisted sequential extraction (UASE). The optimization of the five-step sequential extraction was based on the analysis of SRM 2710 using Tessiers’s method as a reference. Several extracting solutions with different sonication times and temperatures were tested in the optimization procedure. Concentrations of arsenic, cadmium, copper, lead, and zinc were determined in SRM 2710, SRM 2711, and contaminated soil samples with high accuracy and precision. The certified acid-leachable concentrations of the SRM 2710 were obtained for all elements investigated by using an optimized UASE method. Tessiers’s method yielded total element concentrations that were too high. The determination of zinc in SRM 2711 yielded concentrations that were too low, whereas arsenic determination yielded concentrations that were too high by the UASE method and analysis by ICP-OES. The analysis of the SRMs showed that the UASE method is highly comparable with the other methods used for such purposes. The major advantages of the UASE method are the high treatment rate (40 samples simultaneously with a sonication time of 54 min) and a low sample and reagent usage.     

A review of heavy metal contaminations in urban soils, urban road dusts and agricultural soils from China

This paper reviews quite a few heavy metal contamination related studies in several cities from China over the past 10 years. The concentrations, sources, contamination levels, sample collection and analytical tools of heavy metals in urban soils, urban road dusts and agricultural soils were widely compared and discussed in this study. The results indicate that nearly all the concentrations of Cr, Ni, Cu, Pb, Zn, As, Hg and Cd are higher than their background values of soil in China. Among the cities, the contamination levels of the heavy metals vary in a large range. The geoaccumulation index shows that the contamination of Cr, Ni, Cu, Pb, Zn and Cd is widespread in urban soils and urban road dusts of the cities. Generally, the contamination levels of Cu, Pb, Zn and Cd are higher than that of Ni and Cr. Agricultural soils are also significantly influenced by Cd, Hg and Pb derived from anthropogenic activities. The integrated pollution index (IPI) indicates that the urban soils and urban road dusts of the developed cities and the industrial cities have higher contamination levels of the heavy metals. The comparison of the IPIs of heavy metals in urban soils and urban road dusts of Shanghai, Hangzhou, Guangzhou and Hongkong reveals that the contamination levels of the metals in urban road dusts are higher than that in urban soils in the cities. Moreover, the main sources of the metals in urban soils, urban road dusts and agricultural soils are also different.     

Gas chromatography - optical fiber detector for assessment of fatty acids in urban soils

Fatty acids have been used as biomarkers of the microbial community composition of soils and they are usually separated and quantified by gas-chromatography coupled to a flame ionization detector (GC-FID). The aim of this study was to develop, validate and apply a methodology based on gas chromatography coupled to optical fiber detection (GC-OF) for screening five fatty acids used as indicators of fungal and bacterial communities in urban soils. The performance of the GC-OF methodology (optical fiber detector at 1550 nm) was evaluated by comparison with the GC-FID methodology and it was found that they were comparable in terms of linear range, detection limit and analytical errors. Besides these similar analytical characteristics, the GC-OF is much cheaper than the GC-FID methodology. Different concentrations were determined for each fatty acid indicator which in turn varied significantly between the soil samples analyzed from Lisbon ornamental gardens. Additionally, the GC-OF showed a great potential as alternative for determination of eleven or more fatty acids in urban soils.     

Determination of essential and potentially toxic trace elements in honey by inductively coupled plasma-based techniques

The mandate assigned by the European Union to the Community Reference Laboratory for residues at the Istituto Superiore di Sanità covers, among other things, the assessment of trace elements in living animals as well as their products. To better protect the health of the consumer, this task aims in particular at harmonizing the procedures in use at the National Reference Laboratories (NRLs) for residues of the Member States for such determinations as well as at developing new approaches wherever the need arises. In this context an investigation was undertaken to appraise the average levels of a number of key elements in several types of honey with special regard to the influence of the various processing steps. Instrumental methods of election for the analysis of this matrix turned out to be inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) depending on the actual concentrations of the elements of interest. Dissolution of the samples for suitable presentation to the analytical systems could be easily achieved by gentle heating at ca. 50 degrees C, sonication and addition of high-purity water. The ranges ascertained are as follows (in ng g(-1)): As, <0.50-0.70; Cd, <0.50-0.74; Cr, 1.03-3.93; Cu, 144-216; Fe, 191-651; Mn, 223-580; Ni, 17-49; Pb, 3.20-186; Pt, <0.50; Sn, <4-27; V, 1.22-1.94; and Zn, 565-1144. As a rule, concentrations of elements in honey from different beehives were similar. A few exceptions were noted for As, Cu, Fe, Ni and Zn. On the other hand, although data obtained with different analytical approaches for the same types of honey and beehive were generally in good agreement, yet some inconsistencies occurred, as in the case of Cu in freshly collected, extracted and ripened honey, Ni in extracted honey and Fe in ripened honey. These could not be traced back to specific procedural facts; rather, they should be ascribed to the inherent heterogeneity of the raw material. The experience gained with this exploratory study will be exploited to set up wider surveys and to plan the preparation of a new certified reference material in a matrix of honey to the benefit of NRLs for residues.     

Impact of ageing on the distribution of platinum group elements and catalyst poisoning elements in automobile catalysts

The distribution of platinum group elements (PGEs) and catalyst poisoning elements (Pb, Zn, P and S) on the surface of gasoline and diesel automobile catalysts was investigated within this study. Laser ablation–inductively coupled plasma mass spectrometry (LA–ICPMS) provides both the sensitivity and the spatial resolution required for the surface analysis of sectioned automobile catalysts, and scanning along channels reveals the distribution of longitudinal changes in PGE and catalyst poisoning elements. Changes in catalyst surface features were studied for fresh catalysts and after ageing of the catalyst up to 80 000 km for both types of catalysts studied. The PGEs in the gasoline catalyst were found to decrease at the front of the catalyst after ageing, whereas the diesel catalyst presented a more constant loss along the catalyst. The fraction of poisoning elements (Pb, P and Zn for the gasoline catalyst and P and Zn for the diesel catalyst) retained by the catalyst is distributed non‐uniformly over the length of the catalyst. This could indicate different ageing mechanisms for gasoline and diesel catalysts. Copyright © 2003 John Wiley & Sons, Ltd.     

The handbook of analytical methods for trace elements as adopted by the national reference laboratories for residues

The instrumental approaches, quality assurance schemes and management of chemical laboratories should in general be harmonized at the highest possible level. This is all the more so for the national reference laboratories (NRLs) for residues in live animals and their products which have to implement quality assurance systems inspired to the principles of good laboratory practice as well as to the general norms for the operation of testing laboratories (EN 45000 criteria). Directive 23/96/EC of 29 April 1996 prescribes that NRLs are assisted in this process by the four community reference laboratories (CRLs) for residues. To this end, the Rome CRL systematically collects in a handbook all the analytical methods in use at NRLs for the determination of As, Cd, Cu, Hg and Pb, as well as other chemical elements, in animal matrices. One major goal of this action is to foster the harmonization of analytical approaches by the NRLs and their ability to provide comparable results of similar quality. The Rome CRL is committed to revise this handbook twice a year. The role of the handbook is also to encourage the exchange of information among the NRLs as regards the possibility of improving existing methods.     

Potential hazards and health assessment associated with different water uses in the main industrial cities of Egypt

Deterioration of water quality has become an ecological threat in many industrial areas worldwide due to unmanaged anthropogenic activities. Contaminants therein find out their ways to drinking water-pipes via broken or leak old- pipes. The current study aims at evaluating the suitability of tap water, collected from the main-ten-industrial cities of Egypt, for drinking purposes. Shallow and deep ground waters were also sampled from the same locations. This is one of the few research projects that are interested in quantifying the acrylamide in drinking water. The obtained results indicate that concentrations of COD, BOD, Fe, Mn, Ni, Pb, Cd, Zn and Hg were within the permissible levels in tap water while surpassed these levels in both shallow and deep ground waters. Acrylamide levels did not exceed the acceptable levels in all water samples (drinking, surface and deep ground waters). Overall, no potential risks were associated with the oral ingestion of tap water in all studied locations for both adults and children (all hazard quotient (HQ) values, defined as exposure intake dose of contaminants relative to the maximum permissible daily intake dose were below “1″). However, inorganic pollutants that exist in ground waters may cause undesirable dermal impacts when used for irrigating the green areas in these cities (used for picnics and as playgrounds). In this context, most HQ values associated with ground water dermal contact were above “1”. Specifically, Mn, Ni, Pb and Cd hazards exist for children (HQ > 1) while Ni, Pb and Cd toxicity detected for adults. This result; therefore, highlights the indirect negative impacts of industrialization on human health.     

Levels of essential and potentially toxic trace metals in Antarctic macro algae

Eleven species of Antarctic algae were examined for their accumulation ability in the uptake of different metals and metalloids from the Antarctic aquatic environment. Macro algae were collected during the 2000 austral summer season at Jubany Station (Argentinean base) around Potter Cove, King George Island. The elements quantified were: As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, V, and Zn. An optimized microwave-assisted digestion procedure was used to digest the samples and the elements were determined by inductively coupled plasma optical emission spectrometry. A wide range of metal retention capacity among the different species was observed. The highest levels of trace elements were found in Monostroma hariotii and Phaeurus antarcticus, with concentrations up to 3095 μg g⁻¹ for Fe. On the basis of the levels of trace elements observed in Monostroma hariotii and its wide distribution in the Antarctic Peninsula, this organism accomplishes a number of prerequisites to be considered as an adequate biomonitor for future studies.     

Determination of toxic elements in coal by ICP-MS after digestion using microwave-induced combustion

A microwave-induced combustion (MIC) procedure was applied for coal digestion for subsequent determination of As, Cd and Pb by inductively coupled plasma mass spectrometry (ICP-MS) and Hg using cold vapor (CV) generation coupled to ICP-MS. Pellets of coal (500 mg) were combusted using 20 bar of oxygen and ammonium nitrate as aid for ignition. The use of nitric acid as absorbing solution (1.7, 3.5, 5.0, 7.0 and 14 mol L⁻¹) was evaluated. For coal samples with higher ash content, better results were found using 7.0 mol L⁻¹ HNO₃ and an additional reflux step of 5 min after combustion step. For coal samples with ash content lower than 8%, 5.0 mol L⁻¹ nitric acid was suitable to the absorption of all analytes. Accuracy was evaluated using certified reference material (CRM) of coal and spikes. Agreement with certified values and recoveries was better than 95 and 97%, respectively, for all the analytes. For comparison of results, a procedure recommended by the American Society of Testing and Materials (ASTM) was used. Additionally, a conventional microwave-assisted digestion (MAD) in pressurized vessels was also performed. Using ASTM procedure, analyte losses were observed and a relatively long time was necessary for digestion (>6 h). By comparison with MAD procedure, higher sample mass can be digested using MIC allowing better limits of detection. Additionally, the use of concentrated acids was not necessary that is an important aspect in order to obtain low blank levels and lower limits of detection, respectively. The residual carbon content in digests obtained by MAD and MIC was about 15% and <1%, respectively, showing the better digestion efficiency of MIC procedure. Using MIC it was possible to digest completely and simultaneously up to eight samples in only 25 min with relatively lower generation of laboratory effluents.     

Estimation of the bio-accessible fraction of Cr,As, Cd and Pb in locally available bread using on-line continuous leaching method coupled to inductively coupled plasma mass spectrometry

A previously developed, efficient and simple on-line leaching method was used to assess the maximum bio-accessible fraction (assuming no synergistic effect from other food and beverage) of potentially toxic elements (Cr, As, Cd and Pb) in whole wheat brown and white bread samples. Artificial saliva, gastric juice and intestinal juice were successively pumped into a mini-column, packed with bread (maintained at 37 °C) connected on-line to the nebulizer of an inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with a collision-reaction interface (CRI) using hydrogen as reaction gas to minimize carbon- and chlorine-based polyatomic interferences. In contrast to the conventional batch method to which it was compared, this approach provides real-time monitoring of potentially toxic elements that are continuously released during leaching. Mass balance for both methods was verified at the 95% confidence level. Results obtained from the whole wheat brown and white bread showed that the majority of Cr, Cd and Pb was leached by gastric juice but, in contrast, the majority of As was leached by saliva. While there was higher total content for elements in whole wheat bread than in white bread, a higher percentage of elements were bio-accessible in white bread than in whole wheat bread. Both the on-line and batch methods indicate that 40–98% of toxic elements in bread samples are bio-accessible. While comparison of total analyte concentrations with provisional tolerable daily intake values may indicate some serious health concern for children, when accounting for the bio-accessibility of these elements, bread consumption is found to be safe for all ages.     

ICP-MS测定土壤中的部分重金属元素*

本文采用ICP-MS法测定了土壤国家标准样品中的部分重金属元素(Cd、Cu、Pb、Zn、Cr、 Ni、Mo)的含量,其测定值与推荐值相符,准确度符合要求。各元素方法的检出限满足要求,精密度介于0.91％～4.34％,加标回收率介于94％～106％。该方法简便快速,结果准确,可以运用于大批量地质样品中的部分重金属元素含量的同时测定。