Assessment of trace elements characteristics and human health risk of exposure to ambient PM2.5 in Hangzhou,China

A method for simultaneously determining the trace elements in particulate matter (PM) (PM2.5) by inductively coupled plasma mass spectrometry was established. The PM2.5-loaded filter samples were digested under the optimised conditions including a mixture of HNO₃–HCl–HF with ultrasonication proceeding at 70°C for 2 h. Recoveries of 90.83–103.33% were achieved for 20 elements (Co, Sr, Ag, Cd, Sb, La, Ce, Sm, W etc.) in NIST standard reference material 1648a (urban PM). PM2.5 samples were collected at urban site in Hangzhou from August 2015 to November 2015. PM2.5 concentrations of 15% sampling days exceeded the daily limitation and the mean concentrations of PM2.5 from August to November reached the 66.4% of the limitation. PM2.5 concentrations in summer were higher than that in autumn. The concentration of Zn was highest, following with Al, Pb, Mn, Cu and As. Significant enrichment was observed in Mn, Zn, Pb, Ag, V, Ni, Cu, As, Se, Hg, Co, Cd and W, which was probably induced by vehicular exhaust, oil and residual fuel combustion and industrial emissions. The daily mass concentrations of PM2.5 and elements fluctuated significantly. Rainfall could significantly reduce the concentration of Ti, Mn, Cu, Zn, As, Se, Hg, Sr, Ag, Cd, Sb, La, Ce, Sm and Pb, and the risk levels of carcinogenic elements and non-carcinogenic elements in rain day were significantly lower (43.7–81.4%) than those in non-rain day. The risk levels of Co, Cd and As could lead to adverse health outcomes through the respiratory system, which should deserve more attention, while the risk levels of Ni and non-carcinogenic elements (Hg, Mn, Cu, Zn, Pb, V) were under average risk acceptance.     

Determination of As, Sb, Bi and Hg in water samples by flow-injection inductively coupled plasma mass spectrometry with an in-situ nebulizer/hydride generator

A simple and very inexpensive in-situ nebulizer/hydride generator was used with inductively coupled plasma mass spectrometry (ICP-MS) for the determination of As, Sb, Bi and Hg in water samples. The application of hydride generation ICP-MS alleviated the sensitivity problem of As, Sb, Bi and Hg determinations encountered when the conventional pneumatic nebulizer was used for sample introduction. The sample was introduced by flow injection to minimize the deposition of solids on the sampling orifice. The elements in the sample were reduced to the lower oxidation states with L-cysteine before being injected into the hydride generation system. This method has a detection limit of 0.003, 0.003, 0.017 and 0.17 ng ml⁻¹ for As, Bi, Sb and Hg, respectively. This method was applied to determine As, Sb, Bi and Hg in a CASS-3 nearshore seawater reference sample, a SLRS-2 riverine water reference sample and a tap water collected from National Sun Yat-Sen University. The concentrations of the elements were determined by standard addition method. The precision was better than 20% for most of the determinations.     

Chemical characterization of airborne particulate matter in ambient air of Nagoya, Japan, as studied by the multielement determination with ICP-AES and ICP-MS.

The multielement determination of PM(10) (airborne particulate matter smaller than 10 microm) samples, which was collected by a high volume air sampler at the urban site of Nagoya City, was carried out by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The present analytical method was validated by analyzing urban particulate matter standard reference material of NIST SRM 1648. The analytical data for ca. 30 elements in PM(10) samples collected during a period from 8 September to 9 October, 2003, were obtained in the concentration range from sub-microg g(-1) to several-10 mg g(-1), but the data for 18 elements among ca. 30 elements were available for the characterization of PM(10) samples in ambient air, because of problems caused by the filter blanks. Then, the trends concerning the distributions of diverse elements in PM(10) samples were analyzed based on the enrichment factors and size distribution factors. The lithophile and siderophile elements were distributed more than 50% in coarse particle fraction (>2.1 microm), which was derived mainly from natural sources, such as soils and crustal minerals. On the other hand, chalcophile elements were distributed more than 50% in fine particle fraction (<2.1 microm), which was derived mostly from anthropogenic emission sources. The large enrichment of chalcophile elements in PM(10) samples as well as their mining influence factors (MIFs) suggested their wide use in industrial productions.     

ICP-AES法测定化妆品中铅、镉、砷、汞、锑、铬、镍、钡、锶等禁限用元素含量

建立了化妆品中铅(Pb)、镉(Cd)、砷(As)、汞(Hg)、锑(Sb)、铬(Cr)、镍(Ni)、钡(Ba)、锶(Sr)含量的电感耦合等离子体原子发射光谱法(ICP-AES)同步检测技术。采用微波消解,在较难消化的化妆品中加HF进行消化,铑(Rh)为内标元素消除基体干扰,以配备耐HF进样系统的ICP-AES进行测定。在0～1.0 mg/L范围内呈现良好的线性关系(相关系数≥0.9999),Pb、Cd、As、Hg、Sb、Cr、Ni、Ba、Sr检出限分别为0.0016,0.0007,0.0021,0.0013,0.0003,0.0009,0.0008,0.0009,0.0021 mg/L,方法回收率80.2%～111%,精密度1.7%～8.2%。结果表明,该方法适用于检测基体复杂的化妆品中Pb、Cd、As、Hg、Sb、Cr、Ni、Ba、Sr。     

Determination of trace elements in coal and coal fly ash by joint-use of ICP-AES and atomic absorption spectrometry

Microwave-acid digestion (MW-AD) followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES), graphite furnace atomic absorption spectrometry (GFAAS), and hydride generation atomic absorption spectrometry (HGAAS) were examined for the determination of various elements in coal and coal fly ash (CFA). Eight certified reference materials (four coal samples and four CFA samples) were tested. The 10 elements (As, Be, Cd, Co, Cr, Mn, Ni, Pb, Sb, and Se), which are described in the Clean Air Act Amendments (CAAA), were especially considered. For coal, the HF-free MW-AD followed by ICP-AES was successful in the determination of various elements except for As, Be, Cd, Sb, and Se. These elements (except for Sb) were well-determined by use of GFAAS (Be and Cd) and HGAAS (As and Se). For CFA, the addition of HF in the digestion acid mixture was needed for the determination of elements, except for As, Sb, and Se, for which the HF-free MW-AD was applicable. The use of GFAAS (Be and Cd) or HGAAS (Sb and Se) resulted in the successful determination of the elements for which ICP-AES did not work well. The protocol for the determination of the 10 elements in coal and CFA by MW-AD followed by the joint-use of ICP-AES, GFAAS, and HGAAS was established.     

Determination of uranium and selected elements in Polish dictyonema shales and sandstones by ICP-MS

Inductively coupled plasma mass spectrometry was used for characterization of Polish dictyonema shales and sandstones as a potential source of uranium and other technologically important elements. Influence of sample digestion of these materials for the determinations: U, Th, Cu, Co, Mn, Zn, La, V, Yb, Mo, Ni, Sb and Fe has been tested. The method involved two-step microwave acid digestion, followed by direct determination by ICP-MS. The instrument used for all determinations was ELAN DRC II (Perkin Elmer) with crossflow nebulizer with Scott double-pass spray chamber and Ni cones. Certified Reference Materials were used as a quality control standard to validate the applied analytical procedure. The expanded measurement uncertainty U (k = 2) ranged from 5 to 15 %, in dependence on the element. The obtained results provided information on the contents of minor and trace elements in shales and sandstones depending on their origin. At this moment, these geological deposits can be treated as a potential source of raw elements.     

Quality control materials for the determination of trace elements in airborne particulate matter

The development of quality control materials for the determination of selected trace elements in air pollution studies is described. Three types of test samples were prepared for proficiency testing: (1) filters loaded with PM10 fraction of urban air particulate matter (APM) using high-volume air samplers, which were subsequently divided into smaller sections, (2) a bulk sample of APM collected in an automobile tunnel in Prague, and (3) simulated air filters loaded with APM using a wet deposition process. Homogeneity of the test samples was studied using instrumental neutron activation analysis, proton induced X-ray emission and atomic absorption spectrometry, and inductively coupled plasma optical emission spectrometry and mass spectrometry. Sufficiently homogeneous samples were prepared by all three procedures. The simulated air filters appeared to be the most suitable test samples for proficiency testing.     

Determination of trace elements in ambient aerosol samples

A microwave-assisted digestion procedure using HNO₃, HF, and H₂O₂ has been developed for analysis of elements in ambient particulate matter (PM). The samples are collected on cellulose filters and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS is calibrated with external standards, and recovery of analytes is tested with NIST SRM 1648 Urban Dust. This method has been used to quantify the airborne concentrations of a large number of elements, including Ag, As, Ba, Be, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Se, Sb, Sr, Ti, Tl, V, and Zn. For the majority of these elements, recovery of the NIST SRM is within 15% of the certified values.     

Hydride generation atomic fluorescence spectrometric determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter using multivariate optimization

A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2ⁿ + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 × 10⁻³ to 0.2 ng m⁻³ have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruña city (NW Spain).     

Methodological study of extraction procedures applied to urban particulate matter

The modified BCR three-step sequential extraction procedure has been applied to two different samples of urban particulate matters (PM). The distribution of selected trace elements As, Cd, Cr, Mn, Ni, Pb, Zn was investigated and, in a comparative study, the presence of common organic air filters in extraction procedures was evaluated. Analytes in separate fractions were determined by ICP-OES and GFAAS, respectively, depending on concentration levels. While, due to air filters, a significant increase of some analytes mobility in individual fractions has been observed in case of the jet-milled PM (tunnel Letna), but in case of the PKC sample such effect was not found. The analyte impurities built in some filters has been tested, and the impact on the reliability of analyte results has been discussed. The arsenic species occurrence and their stability in presence of air filters (size 47 mm) were investigated in both urban PM samples as well, using HPLC-ICP-MS technique. Water soluble and by three-step BCR procedure extractable arsenic forms are shown in chromatograms     

Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure Part A: Experimental design and optimisation

The optimisation of a micro-analytical two-step sequential leaching procedure for the determination of non-volatile ions (NO₃⁻, SO₄²⁻, Cl⁻, Na⁺, Mg²⁺, NH₄⁺ and Ca²⁺) and of 17 elements (Al, As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, S, Se, V, Zn, Sb, Si and Ti) in two fractions—extract and residue—on the same sample of air particulate matter is described. The two-step method was tested on the SRM NIST 1648 for equivalence with two reference methods, the EMEP procedure for ions extraction and the EN 12341 standard for the elemental determination of the PM₁₀ and is suitable for application to small sample amounts (less than 1 mg of particulate matter is needed), i.e. those collected by daily low volume filter-sampling. Performance times of the procedure were optimised to meet the target of routine application for large scale monitoring samples. A single ultrasonic-assisted extraction of air particulate matter is performed in 0.01 M acetate buffer at pH 4.5, followed by IC ions analysis and ICP-OES elemental analysis of the extract and by ICP-OES elemental analysis of the mineralized residue after dissolution by microwave-assisted digestion with a HNO₃/H₂O₂ mixture. Using a pH buffered extracting solvent was preferred to water or diluted acid solutions to improve the reproducibility of metals extraction with respect to existing leaching methods; the influence of pH, nature and concentration of the buffer solution and extraction time on analytes concentration in the extract is discussed. Values of ions extraction and elements recoveries resulted fairly equivalent with those obtained by the reference methods. The study was also extended to some non-certified elements (Mg, S, Sb, Si and Ti) for their environmental significance. Elements recoveries were obtained as sum of the extract and residue fractions and were comparable with those obtained by direct dissolution. Standard deviations were within 10% for almost all detected ions and elements.     

Ultrasonic dissolution for ICP-MS determination of trace elements in lightly loaded airborne PM filters

A simple single-step ultrasonic dissolution procedure for low mass (<1?mg) particulate matter (PM) filter samples using HNO₃–HF acid solution is proposed for multi-element determination using ICP-MS. The PM-loaded PTFE filter samples are inserted directly into disposable centrifuge tubes for acid extraction using ultrasonic digestion (UD). Potential interferences owing to contamination and element loss are minimized. Key factors influencing element recoveries are investigated, including digestion solution composition, acid concentration, temperature, and matrix interferences. Optimized conditions for UD include an acid mixture consisting of 4.0?mL HNO₃ and 0.1?mL HF with ultrasonication proceeding at 90°C for one hour, followed by 10-fold dilution. Recoveries of 80–120% are achieved for almost all of the 20 elements tested (Be, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Ba, Pb and U) in four standard reference materials with contrasting matrices: NIST 1648 (urban PM), NIST 2584 (indoor dust), NIST 2710 (soil), and NIST 1633b (coal fly ash). The exception is Cr in NIST 1648 for which recovery is low (30%) using this method. Element concentrations obtained for PM-loaded filter samples using the proposed UD?+?ICP-MS method agree with results obtained using energy dispersive X-ray fluorescence (paired t-test p?>?0.2; 95% CI).     

Simultaneous determination of arsenic, antimony, bismuth and mercury in geological materials by vapor generation-four-channel non-dispersive atomic fluorescence spectrometry

Chemical vapor generation (CVG) coupled with non-dispersive atomic fluorescence spectrometry (NDAFS) has been widely used for determination of vapor-forming elements, but most of such works have been focused on single element analysis, and reports dealing with more than three elements simultaneous determination by CVG-NDAFS are rare. In this work, a sensitive and robust analytical procedure for the simultaneous determination of arsenic, antimony, bismuth and mercury in geological materials using vapor generation-four-channel non-dispersive atomic fluorescence spectrometry has been developed. The conditions of instrumentation and vapor generation of arsenic, antimony, bismuth and mercury were optimized. The optimized concentrations of KBH(4) and HCl required for analytes generation were 1.3% (m/v) and 20% (v/v), respectively. The interferences of coexisting ions and mutual hydride interferences were investigated carefully. One thousand milligrams per litre of Fe(3+); 500mgl(-1) of Pb(2+), Zn(2+), Mn(2+); 50mgl(-1) Cu(2+), Ni(2+), Cr(6+), Co(2+); 10mgl(-1) Ag(+) and 5mgl(-1) Au(3+) does not interfere with the determination of As, Sb, Bi and Hg. Associating a dilution of 1:250 (m/v) in the procedure of sample pretreatment, the tolerant concentrations of As, Sb, Bi and Hg in real geological materials are 2500, 1000, 250 and 5000ppm, respectively. Under optimal conditions, the detection limits for As, Sb, Bi and Hg were determined to be 0.068, 0.047, 0.037 and 0.008ngml(-1), respectively. The precisions for seven replicate determinations at the 5ngml(-1) of As, Sb, Bi and 1ngml(-1) of Hg were 0.47, 0.60, 0.97 and 0.93% (R.S.D.), respectively. Sample digestion was carried out on 500mg sample with 3ml HNO(3) and 10ml HCl, followed by addition of thiourea solution for the quantitative reduction of As(V), Sb(V) to As(III), Sb(III). The proposed method was successfully applied to the simultaneous determination of As, Sb, Bi and Hg in a series of certified geological reference materials using simple aqueous standard calibration technique. The results obtained are in good agreement with the certified values.     

ICP-MS determination of trace elements in aerosols using a dynamic reaction cell: first results in PM10 comparing road and aerial traffic in Nice area (France)

An analytical methodology was developed for the determination of 21 trace elements in suspended particulate matter (PM) using a microwave digestion procedure associated with an inductively coupled plasma mass spectrometry (ICP-MS). The dynamic reaction cell (DRC) of the instrument was carefully optimized to eliminate polyatomic species causing spectral interferences for three specified elements (Cr, Fe, Mn). With this method, the detection limits based on the analysis of seven quartz fibre filters (QFF) considering a one-week sample (250 m3) varied between 0.2 and 650 pg m(-3) for trace elements and between 2.1 and 5.6 ng m(-3) for major elements (Fe, Ti, Zn). The recovery of the analytes was tested with NIST SRM 1648 urban dust within 10% of the certified values only for 3-4 mg of material. The first results were discussed for a field campaign which was carried out simultaneously in the heaviest traffic road tunnel of the centre of Nice and near the landing-taking-off runways in the international airport of Nice C?te d'Azur. The behaviour of some combustion tracers was especially studied.     

Determination of As,Cd, Pb,and Hg in urine using inductively coupled plasma mass spectrometry with the direct injection high efficiency nebulizer

The application of the large-bore direct injection high efficiency nebulizer (LB-DIHEN) for the determination of arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in urine by inductively coupled plasma mass spectrometry (ICP-MS) is described. The LB-DIHEN is compared with the standard method using a concentric pneumatic nebulizer and cyclonic spray chamber. In addition to the toxicological significance of As, Cd, Pb, and Hg, these elements represent a cross-section of analytical issues including spectral interferences (e.g., ⁴⁰Ar³⁵Cl⁺ on ⁷⁵As⁺ and ⁹⁸Mo¹⁶O⁺ on ¹¹⁴Cd⁺) and memory effects (Hg). In this study, the low sample consumption of the LB-DIHEN is used to reduce the volume of urine needed for analysis, and to reduce the volume of final diluted sample required for analysis. Eliminating the spray chamber and reducing the dead volume of the nebulizer reduces memory effects, especially for analytes such as Hg. The Dynamic Reaction Cell (DRC) is used in this study to attenuate the background level of ArCl⁺ in spite of the increase in the solvent load and, in turn, the urine matrix (chloride) delivered to the plasma by the LB-DIHEN. This is the first report on coupling the LB-DIHEN to a standard autosampler for unattended sample analysis. The robustness of direct injection nebulization for routine analysis and the issues associated with automation of the sample introduction process are discussed. Although the figures of merit (sensitivity, limit of detection, and precision) determined for both nebulizers are slightly poorer for the LB-DIHEN than for the concentric pneumatic nebulizer, there is not a clinically significant difference between the results for both sample introduction systems. The accuracy of results is assessed using archived urine materials that are circulated by several different proficiency testing (PT) programs and external quality assessment schemes (EQAS). Results obtained using the LB-DIHEN were within the acceptable range established by a consensus pool generated using different methods, none of which are likely to be using direct injection nebulization. Internal quality control sample results obtained using the LB-DIHEN were compared to those obtained using the conventional nebulizer. Reported results were similar for both nebulizers. Thus, these results show that the LB-DIHEN is certainly feasible for the analysis of urine specimens.     

Inductively coupled plasma optical emission spectrometry for trace multi-element determination in vegetable oils,margarine and butter after stabilization with propan-1-ol and water

The quantitative evaluation of trace elements in foodstuffs is of considerable interest due to the potential toxicity of many elements, and because the presence of some metallic species might affect the overall quality (flavor and stability) of these products. In the present work, an inductively coupled plasma optical emission spectrometric method has been developed for the determination of six elements (Cd, Co, Cr, Cu, Ni and Mn) in olive oil, soy oil, margarine and butter. Organic samples (oils and fats) were stabilized using propan-1-ol and water, which enabled long-time sample dispersion in the solution. This simple sample preparation procedure, together with an efficient sample introduction strategy (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber), facilitated the overall analytical procedure, allowing quantification using calibration curves prepared with inorganic standards. Internal standardization (Sc) was used for correction of matrix effects and signal fluctuations. Good sensitivities with limits of detection in the ng g⁻¹ range were achieved for all six elements. These sensitivities were appropriate for the intended application. The method was tested through the analysis of laboratory-fortified samples with good recoveries (between 91.3% and 105.5%).     

An environmental pollution study of Indian metropolitan cities and Industrial surroundings by INAA

The process of urbanization and industrialization during las two decades has resulted in increased level of air pollution causing hazards to human health. Instrumental neutron activation analysis (INAA) using short and long term irradiation has been employed for the determination of more than 30 elements in suspended particulate matter (SPM) from six metropolitan cities and three industrial surroundings. A comparison of mean elemental contents in dust particulates from commercial, industrial and residential zones of Delhi, Calcutta, Madras, Cochin, Bombay and Nagpur cities has shown wide variation in toxic pollutant (As, Br, Cr, Cu, Hg and Sb) concentrations. Coastal areas have shown higher concentrations of Na, K, Cl and Br. Highly industrialized Bombay showed highest levels of Br, Cl, Cr, Fe, Mg, P, Rb and Sc. Mean elemental contents in fugitive and ambient dust of a cement factory and thermal power station (both in central India) are widely different. SPM levels in fugitive dust of the two industrial surroundings are higher by an order of magnitude compared to ambient air. Analysis of ambient air dust from a paper mill showed highest concentrations of Hg, Sb and Zn. Elemental data have been compared with those of Urban Particulate Matter (SRM 1648), Coal Fly Ash (SRM 1633a) and Vehicle Exhaust Particulate (NIES No. 8) which were analysed for quality control. An attempt has been made to attribute the elemental contents to possible sources of origin.     

Analysis of FDA in-house food reference materials with anticoincidence INAA

In-house reference material (IRM) cocoa powder (CCP) has been in use at US Food and Drug Administration laboratories for about 15 years. A single lot of commercial material was originally characterized for 32 elements by several laboratories and five techniques. A unique approach for basis weight determination based upon ambient relative humidity was developed for CCP, eliminating the need for dry weight determinations. The CCP Reference Sheet is updated by incorporating new results approximately every 5 years. The last update occurred in 2006. As part of an effort to revalidate and update values for CCP, anticoincidence instrumental neutron activation analysis (INAA) was used to determine mass fractions for 16 of the originally characterized elements, as well as to provide information on 16 other elements. Results were in very good agreement with 2006 Reference Sheet values. A new candidate IRM, fresh-frozen swordfish (FFSF) powder, was produced by adding inorganic As, Cd, Cr, Hg, Pb, Sb, and Se to liquid nitrogen-frozen commercial swordfish filets which were then homogenized. Portions of FFSF were analyzed by INAA to provide mass fraction and homogeneity information for As, Cd, Cr, Hg, Sb, and Se as well as for eight other elements occurring naturally in the material. Non-homogeneities were ≤2.5 % for As, Br, Cd, and Cs, and ≤1.8 % for Cr, Hg, Rb, Sb, and Se. Certified reference materials DORM-3 Fish Protein powder and fresh-frozen SRM 1947 Lake Michigan Fish Tissue were analyzed as controls.     

Comparison of several spray chambers operating at very low liquid flow rates in inductively coupled plasma atomic emission spectrometry

Four different spray chambers were evaluated in ICP-AES at very low liquid flow rates: a double-pass (Scott type), a conventional cyclonic, and two low-volume cyclonic-type spray chambers (i.e., Cinnabar and Genie). A glass concentric pneumatic micro nebulizer (Atom Mist) was used in conjunction with all four chambers. The liquid flow rate was varied from 10 to 160 microL min(-1). The conventional cyclonic spray chamber gave rise to coarser tertiary aerosols, higher analyte and solvent transport rates, higher sensitivity and lower limits of detection than the remaining ones. The low-volume spray chambers afforded analytical figures of merit similar to the double-pass one, despite their very different designs. However, these spray chambers exhibited shorter wash-out times. The matrix effects were significant only for the double-pass. This fact allowed the analysis of reference samples by employing aqueous standards at a minimum level of sample consumption. The recoveries obtained for the cyclonic spray chambers and several certified samples were close to 100%, being always lower in the case of the double-pass spray chamber.     

Determination of As,Cd, Cr,Cu, Hg,Sb and Se concentrations by radiochemical neutron activation analysis in different Brazilian regional diets

The present paper describes radiochemical separation procedures developed for the determination of seven elements: As, Cd, Cr, Cu, Hg, Sb and Se in different Brazilian regional diets. In the case of the elements As, Hg, Sb and Se, the procedure was based on retention in inorganic exchanger TDO (tin dioxide) and determination of Hg by extraction with Ni(DDC)₂. For determination of Cd, Cr, Cu and Se the procedure chosen was based on retention in inorganic exchanger HMD (hydrated managese dioxide) and extraction of Cu and Cd as diethyldithiocarbamate compounds. The accuracy and precision of the methods studied were tested by means of analyses of different reference materials. Due to the lack of data on trace element levels in Brazilian foodstuffs and diets, these methods were applied to determination of these elements in different Brazilian regional diets. These diets were supplied by the Food and Experimental Nutrition Department of the Faculty of Pharmaceutical Science, University of São Paulo. The daily dietary intake values for these diets are presented for As, Cd, Cr, Cu, Hg, Sb and Se.