Fast automated determination of toxicologically relevant arsenic in urine by flow injection-hydride generation atomic absorption spectrometry

Determination of toxicological relevant arsenic species in urine by hydride generation microwave-induced plasma optical emission spectrometry

An analytical method for the determination of toxicological relevant species of arsenic in urine was developed and validated using hydride generation microwave-induced emission spectrometry (HG-MP-AES). This strategy can be used as an alternative to HG-HPLC-ICP-MS considered as a reference technique for arsenic speciation. This procedure is notably less expensive than other techniques and sample preparation and requires only a few steps.•Hydride generation with MP-AES detection has proven to be an effective technique for measuring arsenic metabolites in urine, which is relevant for occupational monitoring and health risk assessment purposes.•This method offers simplicity and cost-effectiveness, serving as an alternative to classical analytical procedures typically used for arsenic analysis in urine.•The methodology has been successfully applied for the purpose of workers' health surveillance.

Rapid detection of ultratrace urinary arsenic by direct sampling microplasma vaporization based on silicon nitride

At present, immediate monitoring urinary arsenic is still a challenge for treating arsenic poisoning patients. Thus, a fast, reliable and accurate analytical approach is indispensable to monitor ultratrace arsenic in urine sample for health warning. In this work, a silicon nitride (SN) rod was first integrally utilized as a sample carrier for ≤50 μL urinary aliquot, an electric heater for removing water and ashing sample as well as a high voltage electrode for dielectric barrier discharge vaporization (DBDV). The direct analytical method of arsenic in urine without sample digestion was thus developed using atomic fluorescence spectrometer (AFS) as a model detector. After 4 V electrically heating the SN rod for 60 s, urine sample was dehydrated and ashed outside; then, DBD was exerted under 0.8 A with 0.8 L/min H₂ + Ar (1:9, v:v) for 20 s to vaporize arsenic analyte from the SN rod. After optimization, 0.014 μg/L arsenic detection limit (LOD) was reached with favorable analytical precision (RSD <5%) and accuracy (91-110% recoveries) for real sample analysis. As a result, the whole analysis process only consumes <3 min to exclude complicated sample preparation; furthermore, the designed DBDV system only occupies 25 W and <2 kg, which renders a miniature sampling component to hyphenate with a miniature detector to detect arsenic. Thus, this direct sampling DBDV method extremely fulfills the fast, sensitive and precise detection of ultratrace arsenic in urine sample.

Contribution to the understanding of biologic concentrations of arsenic in children living in an urban area from Rio de Janeiro, Brazil

There are few studies about children's environmental exposure to arsenic (As) in Brazil, most of them being in mining regions. The objective of this study was to contribute to the understanding of biologic concentrations of arsenic in children living in an urban area, in Brazil. A study of arsenic concentrations in capillary blood (n = 270), nail (n = 261), and urine (n = 99) samples, in male and female children, 8 to 10 years old, from two public schools in Rio de Janeiro, was conducted. Socio-economic and health data were obtained through questionnaires. The nail and capillary blood analysis were performed by inductively coupled plasma mass spectrometry (ICP-MS), while urine samples were analyzed using hydride generation atomic absorption spectrometry (HG-AAS). The median, geometric mean, and 95th percentiles of total arsenic concentrations were, respectively, 2.53, 2.40, and 3.58 μg/L in capillary blood; 0.09, 0.10, and 0.24 μg/g in nails; and 12.50, 10.97, and 39.45 μg/L in urine. The geometric mean of urinary arsenic level was above the values reported by international surveys for non-exposed populations. The arsenic concentrations in nails were compatible with the values found in national studies. These outcomes can contribute to the increase of knowledge on biologic concentrations of arsenic in children living in urban areas, in Brazil.

A review on exposure and effects of arsenic in passerine birds

Arsenic (As) is a metalloid of high concern because of its toxic effects for plants and animals. However, it is hard to find information on this metalloid in passerines. This review presents a comprehensive overview of As exposure and effects in birds, and more particularly in passerines, as a result of an extensive search of the literature available. Internal tissues are the most frequently analyzed matrices for As determination in passerines (37.5% of the reviewed studies used internal tissues), followed by feathers and eggs (32.5% each), feces (27.5%), and finally blood (15%). A clear tendency is found in recent years to the use of non-destructive samples. Most studies on As concentrations in passerines have been done in great tit (Parus major; 50%), followed by pied flycatcher (Ficedula hypoleuca; 22.5%). Some factors such as diet and migratory status are crucial on the interspecific differences in As exposure. More studies are needed to elucidate if intraspecific factors like age or gender affect As concentrations in different tissues. The literature review shows that studies on As concentrations in passerines have been done mainly in the United States (30%), followed by Belgium (22.5%), and Finland (20%), making evident the scarce or even lack of information in some countries, so we recommend further research in order to overcome the data gap, particularly in the southern hemisphere. Studies on humans, laboratory animals and birds have found a wide range of effects on different organ systems when they are exposed to different forms of As. This review shows that few field studies on As exposure and effects in passerines have been done, and all of them are correlative so far. Arsenic manipulation experiments on passerines are recommended to explore the adverse effects of As in free-living populations at similar levels to those occurring in the environment.

CAPSULE

This review summarizes the most interesting published studies on As exposure and effects in passerines.

Association of arsenic levels in soil and water with urinary arsenic concentration of residents in the vicinity of closed metal mines

Arsenic (As) pollution in the surroundings of metal mines has been observed, and may induce serious health problems, in particular cancer. Health hazard attributed to As in contaminated soil and water in the vicinity of closed or abandoned metal mines may be high. Little is known about how environmental exposure to As has affected the health of resident near closed metal mines. The objectives of this study were to compare the urinary level of As for those living near closed metal mines (the exposed group) with that of non-exposed group; and to investigate the correlation between As levels in soil (SoilAs) and water (WaterAs) and the urinary levels (UrineAs) of residents in the exposed group. Data for SoilAs and WaterAs were obtained from the national environmental survey performed between 2003 and 2005 by the Ministry of Environment in Korea. To measure UrineAs, 2674 and 237 subjects were selected from 67 closed metal mines (exposed areas) and two rural areas (non-exposed areas), respectively. Five milliliters of urine samples were taken, and graphite furnace atomic absorption spectrometry was used to analyze UrineAs. Of all the exposed areas, high SoilAs and WaterAs areas that exceed the Korean standards of As in soil (6 mg/kg-soil) and stream or groundwater (0.05 mg/l-water) were classified to evaluate the health risks in high polluted areas. Also, high UrineAs group was defined as 20 μg/g creatinine or more. Student's t-test was performed to compare the UrineAs level between the exposed and non-exposed groups. The odds ratio (OR) was calculated by a logistic analysis to evaluate the risk for high UrineAs level from high SoilAs and WaterAs areas. The mean of urinary As were 8.90 ± 8.34 μg/g-creatinine for the exposed group and 7.68 ± 4.98 μg/g creatinine for the non-exposed group, respectively; and the significant difference of urinary As level was observed between both groups (p<0.05). Moreover, the means for urinary As of people in areas with high As level in soil and water were significantly higher than that for the control areas (p<0.001), and these differences were more pronounced for the As level in water. The odds of subjects with high UrineAs were positively and significantly associated with living in the areas with high As level in soil (OR=1.62; 95% C.I.=1.13-2.31). These associations were much stronger for the areas with high WaterAs (OR=3.79; 95% C.I.=2.32-6.19). These results indicate that the high level of As in environment may increase the risk of having high urinary As level of people in the exposed areas.

Effects of low-level arsenic exposure on urinary N-acetyl-β-D-glucosaminidase activity

This study was aimed to evaluate whether renal tubular function is impaired by exposure to relatively low concentrations of arsenic. Mean urinary arsenic concentrations and N-acetyl-β-D-glucosaminidase (NAG) activities were compared among 365 and 502 Korean men and women, respectively, in relation to gender, smoking, alcohol consumption, and recent seafood consumption. The study subjects were divided into 4 groups according to urinary NAG activity and seafood consumption prior to urine sampling, and the correlation between arsenic concentration and urinary NAG activity was tested for each group. The mean urinary arsenic level was higher in women, non-smokers, and non-drinkers in comparison to men, smokers, and drinkers, respectively. Individuals who consumed seafood within 3 days prior to urine sampling showed a higher mean urinary arsenic level than those who did not. The correlation between urinary arsenic concentration and NAG activity in urine was significant only in subjects who did not consume seafood within 3 days prior to urine sampling and whose urinary NAG activity was 7.44 U/g creatinine (75th percentile) or higher. The urinary arsenic concentration was a significant determinant of urinary NAG activity in subjects with NAG activity higher than 7.44 U/g creatinine and especially in those who had not consumed seafood recently. These facts suggest that a relatively low-level exposure to inorganic arsenic produces renal tubular damage in humans.

Arsenic exposure assessment of children living in a lead mining area in Southeastern Brazil

Environmental contamination by arsenic compounds in the Ribeira River Valley, São Paulo, Brazil has already been observed. Lead mining and refining activities had been carried on since late colonial times and finished recently, at the end of 1995. The source of As in the region is known to be mainly from arsenopirite geological presence in the lead ore. Chronic exposure to arsenic compounds may cause peripheral vascular disorders, hyperpigmentation, hiperkeratosis and cancer of the skin, bladder, lung, liver and other internal organs. The purpose of this study was to assess children exposure to arsenic from environmental sources in the region. Urine samples from children between 7 to 14 years old were collected at the following localities: Cerro Azul (Paraná); urban areas of Ribeira (São Paulo) and Adrianópolis (Paraná); Vila Mota neighborhood (rural area of Adrianópolis) and Serra neighborhood (Iporanga, São Paulo), identified as groups 1, 2, 3 and 4, respectively. Group 1 was considered as non-exposed control group. Toxicologically relevant forms of As were determined by atomic absorption spectrometry with hydride generation system. The median values of urine arsenic levels obtained in groups 1, 2, 3 and 4 were respectively: 3.60, 6.30, 6.41 e 8.94μg/L.

Influence of EDTA, carboxylic acids, amino- and hydroxocarboxylic acids and monosaccharides on the generation of arsines in hydride generation atomic absorption spectrometry

The influence of EDTA, carboxylic acids, amino-and hydroxocarboxylic acids, monosaccharides and humic substances on the generation of arsines in hydride generation atomic absorption spectrometry (HGAAS) was investigated. EDTA (0.02 mol L−1), ascorbic acid (0.02 mol L−1) and glucose or fructose (0.2 mol L−1) are useful additives for levelling sensitivities for As(III), monomethylarsonate (MMA) and dimethylarsinate (DMA). The presence of glycine, malonic, tartaric acids, BICIN and soil humin extracts leads to differences in analytical signal response between these arsenic species. An analytical application to the determination of the sum of As(III), monomethylarsonate (MMA) and dimethylarsinate (DMA) as well as the sum of toxicologically relevant hydride forming arsenic fraction As(III) + As(V) + MMA + DMA in EDTA soil/sediment extracts using continuous flow HGAAS was demonstrated. The limit of detection was 0.2 mg kg−1 As. Within-day and between-day precision were in the range 3–7% and 4–10%, respectively, for arsenic contents of 0.7–25 mg kg−1, with recoveries 95–103%.

On-line arsenic co-precipitation on ethyl vinyl acetate turning-packed mini-column followed by hydride generation-ICP OES determination

An alternative and new system for on-line preconcentration of arsenic by sorption on a mini-column associated to hydride generation--inductively coupled plasma--optical emission spectrometry determination was studied. It is based on the sorption of arsenic on a column packed with ethyl vinyl acetate (EVA) turnings and the use of La(III) as co-precipitant reagent. This polymeric material was employed here for the first time as filling material for column preconcentration. It could work both as adsorbent and as sieve material. Sample and co-precipitant agent (lanthanum nitrate) were off-line mixed and merged with ammonium buffer solution (pH 10.0), which promoted precipitation and quantitative collection on the small EVA turnings. The arsenic preconcentrated by co-precipitation with lanthanum hydroxide precipitate was subsequently eluted with hydrochloric acid, which was the medium used for hydride generation. Considering a flow rate of 5 ml/min, three enrichment factors were obtained, 28-, 38- and 45-fold at three different sampling times, 60, 120 and 180s; respectively. The detection limits (3s) obtained for each case were 0.013, 0.009 and 0.007 microg/l. Additionally, the calculated precisions expressed as relatively standard deviation (R.S.D.) were 0.9, 1.3 and 1.1%. Satisfactory results were obtained for the determination of arsenic in standard reference material NIST 1643e Trace Elements in Water and drinking water samples.

Arsenic occurrence in Brazil and human exposure

Environmental exposure to arsenic (As) in terms of public health is receiving increasing attention worldwide following cases of mass contamination in different parts of the world. However, there is a scarcity of data available on As geochemistry in Brazilian territory, despite the known occurrence of As in some of the more severely polluted areas of Brazil. The purpose of this paper is to discuss existing data on As distribution in Brazil based on recent investigations in three contaminated areas as well as results from the literature. To date, integrated studies on environmental and anthropogenic sources of As contamination have been carried out only in three areas in Brazil: (1) the Southeastern region, known as the Iron Quadrangle, where As was released into the drainage systems, soils and atmosphere as a result of gold mining; (2) the Ribeira Valley, where As occurs in Pb-Zn mine wastes and naturally in As-rich rocks and soils; (3) the Amazon region, including the Santana area, where As is associated with manganese ores mined over the last 50 years. Toxicological studies revealed that the populations were not exposed to elevated levels of As, with the As concentrations in surface water in these areas rarely exceeding 10 microg/L. Deep weathering of bedrocks along with formation of Fe/Al-enriched soils and sediments function as a chemical barrier that prevents the release of As into the water. In addition, the tropical climate results in high rates of precipitation in the northern and southeastern regions and, hence, the As contents of drinking water is diluted. Severe cases of human As exposure related to non-point pollution sources have not been reported in Brazil. However, increasing awareness of the adverse health effects of As will eventually lead to a more complete picture of the distribution of As in Brazil.

Determination of arsenic(III) by flow injection solid phase extraction coupled with on-line hydride generation atomic absorption spectrometry using a PTFE turnings-packed micro-column

A novel flow injection (FI) solid phase extraction method for the determination of arsenic(III) at trace levels was developed, using on-line hydride generation atomic absorption spectrometry (HG-AAS). Selective determination of As(III) was achieved by on-line formation and retention of the pyrrolidine dithiocarbamate arsenic complex As(III)-PDC on the PTFE turnings which are packed in the preconcentration micro-column. The retained complex was eluted by 2 ml 2 mol l(-1) HCl and subsequently introduced on-line into the integrated reaction chamber/gas-liquid separator (RC-GLS). A 1.5% (m/v) NaBH4 solution was used for arsine generation, while a gas stream of N2 was employed for flash release and transportation towards the atomic absorption flow through cell (AAC) for atomization and measurement. The excellent performance of PTFE turnings as sorbent material and the compact design of the RC-GLS result to high sensitivity, selectivity and sampling frequency. For 60s preconcentration time and sample consumption 10.4 ml a sampling frequency of 25 h(-1) and a detection limit of c(L)=0.02 microg l(-1) were obtained. The repeatability, expressed as relative standard deviation (R.S.D.), at 1.0 microg l(-1) As(III), was s(r)=2.8%. The proposed method was successfully applied to the selective determination of As(III) in natural waters and total arsenic determination in certified reference material.

A study of sample mineralization methods for arsenic analysis of blood and urine by hydride generation and graphite furnace atomic absorption spectrometry

Mineralization procedures for blood and urine suitable for the determination of arsenic by Hydride Generation Atomic Absorption Spectrometry (HGAAS) are studied on model samples, and the results are utilized in biological monitoring investigations. The objective of this work is to obtain good total As recoveries for both matrices regardless of added As species (As(III), As(V), DMA, MMA, AsB, or AsC). Prior to the HGAAS analyses, preparation procedures were controlled under optimised conditions by graphite furnace atomic absorption spectrometry (GFAAS). Two preparation procedures for urine give As recoveries close to 100% by HGAAS: a) dry ashing at 420°C with Mg(NO3)2 on a hot plate, and b) microwave oven decomposition with (NH4)2S2O8. For blood samples, As recoveries by HGAAS range between 95 and 108% for all species when using dry ashing after a pretreatment of samples with HNO3 and H2O2 in a microwave oven. Wet digestion with (NH4)2S2O8 in a microwave oven gives recoveries very near 100% for Asinorg. and MMA. For other As species in spiked blood samples, recoveries of less than 20% As are found. Precision and detection limits obtained by both techniques are evaluated as well. For arsenic concentrations of 20 μg dm−3 or more in blood and urine, a chemical modifier is recommended for GFAAS analysis; it may or may not be proceeded by a mineralization step. For low As levels encountered in the unexposed population, the HGAAS technique provides reliable results only if a very complete mineralization procedure is used.

Population-based biomonitoring in the Czech Republic: urinary arsenic

The method of Guo et aL (AnaL Chim. Acta, 1997, 349, 313-318) for the determination of the toxicologically relevant arsenic in urine was verified and then used for the determination of arsenic in urine of the Czech population for monitoring purposes. Statistical evaluation at the level alpha = 0.05 did not prove any significant differences between industrial and agricultural regions, between males and females and smokers and nonsmokers. Likewise no differences were found among children in all the regions monitored. In the adult population small differences were found between some regions but these differences were not dependent on industrial pollution. The values of toxicologically relevant arsenic are low for all regions. The summarised value of the median for all groups together is 3.5 microg (g creatinine)(-1).