Lead In Biological Samples Research Articles

An Eco‐Friendly Approach for Determination of Lead in Biological Samples after Deep Eutectic Solvent Extraction

AbstractThe present research proposes investigating deep eutectic solvents for extracting Pb from biological samples for further determination by GF AAS. Among the synthesized solvents, the DES obtained from choline chloride and oxalic acid (ChCl : Ox) in a molar ratio 1 : 1 presented the best lead (Pb) extraction efficiency. Subsequently, it was characterized by Fourier Transform Infrared Spectroscopy (FTIR). For extraction, the optimized conditions were: 40 mg of sample, 400 μL of DES (ChCl : Ox) added, and 30 min at 95±5 °C. The supernatant was diluted, and the Pb was determined by GF AAS. The optimized instrumental conditions for Pb determination were 900 °C and 2100 °C, pyrolysis and atomization temperatures, respectively, using Pd as a chemical modifier. The limits of detection and quantification were 0.04 and 0.12 μg g−1, respectively. The method's accuracy was evaluated by analyzing the certificate reference materials, and good agreement was obtained between the determined and certificate values. The greenness of the proposed method was evaluated by green star and eco‐scale metrics. Thus, the proposed method proved simple, efficient, and eco‐friendly for determining Pb in biological samples.

A Portable Microplasma Optical Emission Spectrometric Device with Online Digestion Function for Field and Sensitive Determination of Lead in Biological Samples.

Accurate detection and screening of Pb in biological samples is helpful to assess the risk associated with lead pollution to human health. However, conventional atomic spectroscopic instruments are bulky and cumbersome, requiring additional sample pretreatment equipment, and difficult to perform field analysis with. Herein, a portable point discharge (PD) microplasma-optical emission spectrometric (OES) device with online digestion function is designed for field and sensitive determination of lead in biological samples. With rice as a model, online digestion of a batch of six 50 mg samples can be achieved in the HNO3 and H2O2 system within 25 min by a temperature control and timing module. Compared to the conventional microwave digestion, the digestion efficiency of this device reaches 97%. Pb in digestion solution is converted into volatile species by hydride generation (HG) and directly introduced into PD-OES for excitation and detection by a self-designed rotatable and telescopic cutoff gas sampling column. Six samples can be successively detected in 2 min, and argon consumption of the whole process is only <800 mL. Under the optimized conditions, the detection limit of Pb is 0.018 mg kg-1 (0.9 μg L-1) and precision is 3.6%. The accuracy and practicability of the present device are verified by measuring several certified reference materials and real biological samples. By virtue of small size (23.5 × 17 × 8.5 cm3), lightweight (2.5 kg), and low energy consumption (24.3 W), the present device provides a convenient tool for field analysis of toxic elements in biological samples.

Possibility of the total reflection x-ray fluorescence spectrometer for the determination of lead in biological samples

Mongolia has been exposed to extreme draught and dry summer for its historical development due to geographical location, climatic condition, surface characteristics and being subject to vulnerable and dry region in terms of ecological system. Besides it, rapid increase in the minerals production has been causing heavy metal pollution in soil, water and plants. Soil pollution is main parameter of environmental pollution and air and water pollution directly depend on it. Main influencing factor of endemic diseases of livestock is chemical ingredient of soil, water and plant. Due to negligent use and disposal of lead containing sources including acid and alkali batteries with lead conductor, vehicle accumulators in last years, environment has been polluted greatly and it becomes the cause of animal poisoning. Heavy metals are dangerous because of their persistence and toxicity. Soil behaves as a sink of heavy metals by aerial deposition of particles emitted by human activities. The aims of this work were to identify the levels of lead in accumulator processing plant and city areas and animals. We have determined lead level in biological samples /livestock blood/ using total reflection X-ray fluorescence spectrometer and compared the results found by the Lead Care II.&#x0D; Бүрэн ойлтын рентгенфлоуресценцийн спектрометр ашиглан биологийн дээжинд хартугалга тодорхойлох боломж&#x0D; Хураангуй: Монгол орон газар зүйн байршил, уур амьсгалын нөхцөл, газар нутгийн гадаргын хэв шинж,экологийн тогтолцооны хувьд нэн эмзэг, хуурай бүс нутагт хамрагддагийн улмаас түүхэн хөгжлийнхөө турш ган, зуданд нэрвэгдсээр ирсэн байна. Үүний зэрэгцээ манай оронд ашигт малтмалын олборлолт эрс нэмэгдсэнээр хөрс, ус, ургамал хүнд металлаар ихээр бохирдох боллоо. Хөрсний бохирдол нь байгаль, орчны төлөв байдлын гол үзүүлэлт бөгөөд агаар, усны бохирдол үүнээс шууд хамаарна [1]. Мал, амьтны нутгийн орогнол (эндемик) өвчинд гол нөлөөлөх зүйл бол хөрс, ус, ургамлын химийн найрлага юм. Хар тугалган дамжуулагч бүхий хүчлийн болон шүлтийн батарей, автомашины аккуммулятор зэрэг хар тугалга агуулсан эх үүсвэрүүдийг эмх замбараагүй хаясны улмаас байгаль орчин хар тугалгаар ихээр бохирдож мал, амьтны хордох шалтгаан болж байна. Хар тугалгыг мэдрэлийн хор гэж нэрлэдэг бөгөөдөсөлт, тархины хөгжлийг саатуулах аюултай. Иймд бид бүрэн ойлтын рентген флуоресценцийн аргыг ашиглан биологийн дээжинд (малын цусанд) хар тугалганы хэмжээг тодорхойлон, үр дүнг LeadCare II багажийн хэмжилтийн дүнтэй харьцуулав. Бидний хийсэн хэмжилтийн дүнгээс харахад 2 багажийн тоон үзүүлэлт хамаарлын шугаманд ойролцоо гарч байна.&#x0D; Түлхүүр үг: Хүнд метал, үхэр, цус, дээж

Ultrasonically Dispersed Ionic Liquid-Based Microextraction of Lead in Biological Samples of Malnourished Children Prior to Analysis by Flame Atomic Absorption Spectrometry.

In the present study, a simple ultrasonically dispersed modified liquid-phase microextraction method was developed for the extraction of lead (Pb) from blood and scalp hair samples of malnourished children (MNC). The complexation of Pb was executed by means of the complexing agent, ammonium pyrrolidinedithiocarbamate (APDC), whereas extraction was carried out through the ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate. Ultrasound energy was used for the dispersion and extraction of the metal complex into an IL because it enhances the extraction of the metal complex into infinite IL drops at a temperature range of 40-80°C for 1-5 min. After sonication, the enriched analyte phase was separated by centrifugation. Nitric acid (HNO3; 0.5-2 mol/L) was added to the IL-enriched phase to back-extract the analyte into the acidic aqueous phase and analyzed by flame atomic absorption spectrometry. Various experimental parameters that affect the efficiency of the proposed method, such as volume of IL, concentration of the complexing agent, pH, ultrasonication time and temperature, and concentration of HNO3, were optimized. The enhancement factor was calculated as 70. The LOD for Pb ions was found to be 0.19 μg/L, with an RSD of <5%. Accuracy was ensured by applying the procedure to a certified reference material for whole blood and scalp hair. The developed procedure was successfully applied for the analysis of the concentration of Pb ion in whole-blood and scalp hair samples of MNC from different areas of Sindh, Pakistan. The concentration of Pb among MNC was 2-fold higher than the referent.

Estimation of calcium, magnesium, cadmium, and lead in biological samples from paralyzed quality control and production steel mill workers.

The determination of trace and toxic metals in the biological samples of human beings is an important clinical screening procedure. The aim of the present study was to compare the level of essential trace and toxic elements cadmium (Cd), calcium (Ca), lead (Pb), and magnesium (Mg) in biological samples (whole blood, urine, and scalp hair) of male paralyzed production (PPW) and quality control workers (PQW) of a steel mill, age ranged (35-55 years). For comparison purposes, healthy age-matched exposed referent subjects (EC), working in steel mill and control subjects (NEC), who were not working in industries and lived far away from the industrial areas, were selected as control subjects. The concentrations of electrolytes and toxic elements in biological samples were measured by atomic absorption spectrometry after microwave-assisted acid digestion. The validity and accuracy of the methodology were checked using certified reference materials. The results of this study showed that the mean values of Cd and Pb were significantly higher in scalp hair, blood, and urine samples of PPW and PQW as compared to NEC and EC (p < 0.001), whereas the concentrations of Ca and Mg were found to be lower in the scalp hair and blood but higher in the urine samples of PPW and PQW. The results show the need for immediate improvements in workplace, ventilation, and industrial hygiene practices.

Estimation of lead in biological samples of oral cancer patients chewing smokeless tobacco products by ionic liquid-based microextraction in a single syringe system.

Several studies have reported that the chewing habit of smokeless tobacco (SLT) has been associated with oral cancer. The aim of the present study was to evaluate the trace levels of lead (Pb) in biological samples (blood, scalp hair) of oral cancer patients and referents of the same age group (range 30-60 years). As the concentrations of Pb are very low in biological samples, so a simple and efficient ionic liquid-based microextraction in a single syringe system has been developed, as a prior step to determination by flame atomic absorption spectrometry. In this procedure, the hydrophobic chelates of Pb with ammonium pyrrolidinedithiocarbamate (APDC) were extracted into fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] within a syringe while using Triton X-114 as a dispersant. Factors influencing the microextraction efficiency and determination, such as pH of the sample, volume of [C4MIM][PF6] and Triton X-114, ligand concentration, and incubation time, were studied. To validate the proposed method, certified reference materials were analyzed and the results of Pb(2+) were in good agreement with certified values. At optimum experimental values of significant variables, detection limit and enhancement factor were found to be 0.412 μg/L and 80, respectively. The coexisting ions showed no obvious negative outcome on Pb preconcentration. The proposed method was applied satisfactorily for the preconcentration of Pb(2+) in acid-digested SLT and biological samples of the study population. It was observed that oral cancer patients who consumed different SLT products have 2-3-fold higher levels of Pb in scalp hair and blood samples as compared to healthy referents (p < 0.001). While 31.4-50.8% higher levels of Pb were observed in referents chewing different SLT products as compared to nonconsumers (p < 0.01).

Determination of Lead in Biological Samples of Children with Different Physiological Consequences Using Cloud Point Extraction Method

In present study, lead (Pb) level in biological samples of children with physiological disorders (liver, bone, and gastrointestinal; age ranged 1-10years) have been assessed. For comparison purpose, age-matched healthy children were also selected. Cloud point extraction (CPE) was employed for preconcentration of Pb in acid-digested biological samples prior to its determination by flame atomic absorption spectrometry (FAAS). Dithizone (diphenylthiocarbazone) and nonionic surfactant Triton X-114 (TX-114) were used as complexing reagent and extractant, respectively. The effects of several experimental variables on proposed CPE were evaluated. Under the optimum experimental conditions, the observed detection limit (LOD) and the enhancement factor (EF) were 0.08μgL(-1) and 53, respectively. Relative standard deviation (RSD) of 10μgL(-1) Pb was 3.4%. It was observed that children with liver-, bone-, and gastrointestinal-related disorders had three- to fourfold higher Pb level in blood and scalp hair samples.

Silver Nanoparticles as a New Solid-Phase Adsorbent and Its Application to Preconcentration and Determination of Lead from Biological Samples

A new, simple, and fast method for preconcentration and determination of trace amount of lead from biological samples was developed by modified silver nanoparticle-based solid-phase extraction technique and graphite furnace atomic absorption spectrometry. In this study, morin was used as a complexing agent. Some factors influencing the recovery of lead including pH, sample flow rate, type, flow rate, and least amount of the eluent for elution of the lead from silver nanoparticles were studied and optimized. Under the optimum conditions, the detection limit of this method was 68ngL(-1), and the relative standard deviation was 4.1% (n = 10, c = 20μgL(-1)). The developed procedure was validated by the analysis of certified reference material and applied to the recovery and determination of lead in biological samples.

Determination of cadmium and lead in human biological samples by spectrometric techniques: a review

The analysis of human biological samples, such as blood, urine, nails, and hair, is generally used for the verification of human exposure to toxic metals. In this review, various spectrometric methods for the determination of cadmium and lead in biological samples are discussed and compared. Several spectrometric techniques are presented and discussed with respect to various characteristics such as sensitivity, selectivity, and cost. Special attention is drawn to the procedures for digestion prior to the determination of cadmium and lead in hair, nails, blood, and urine.

Single drop microextraction combined with graphite furnace atomic absorption spectrometry for determination of lead in biological samples

Single drop microextraction combined with graphite furnace atomic absorption spectrometry is introduced for the determination of trace lead in water samples. A drop of 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) dissolved in benzene was held at the tip of a microsyringe and immerged into the sample solution which was stirred, the solvent drop interacts with the sample solution, and the analyte was extracted into the drop and concentrated. After extracting for a period of time, the drop was retracted into the microsyringe and directly injected into graphite furnace for GFAAS determination of Pb. Several factors affecting the extraction efficiency, such as pH of sample solution, drop volume, stirring rate and extraction time, were optimized. Under the optimized conditions, an enhancement factor of 16 was achieved, and the detection limits for Pb were 25 ng L−1. The relative standard deviation for seven replicate determination of 10 ng mL−1 Pb was 6.1%. The method was applied to determine trace Pb in biological samples with satisfactory results.

Determination of Cadmium and Lead in Biological Samples by Three Ultrasonic-Based Samples Treatment Procedures Followed by Electrothermal Atomic Absorption Spectrometry

The development of 3 different ultrasonic-based sample treatment methods, ultrasonic probe-assisted acid extraction, ultrasonic-assisted acid slurry, and ultrasonic-assisted acid pseudodigestion is presented. These methods were compared for the determination of Cd and Pb by electrothermal atomic absorption spectrometry in biological samples (blood and scalp hair) and validated by using certified materials BCR 397 human hair and BCR 185R bovine liver. The sample amounts chosen to perform the analysis were 100 mg and 0.5 mL for solids (human hair and bovine liver) and blood samples, respectively. An acid digestion induced by microwave energy was used to obtain the total metal concentrations and for comparative purposes. The best results were obtained with the ultrasonic-assisted acid pseudodigestion, with which it was possible to perform accurate and precise determination of the Cd and Pb contents in 2 certified reference materials and biological samples of 50 normal males of ages 25-40 years. The precision of the methods, together with their efficiency, rapidity, low cost, and environmental acceptability, make them good alternatives for the determination of trace metals from biological samples. The precision of the methods for accuracy evaluation, resulting in good agreement according to the t-test for a 95% confidence level, and the relative standard deviations were lower than 10% (n=10) for all determinations.

A simple spectrophotometric method for the determination of trace level lead in biological samples in the presence of aqueous micellar solutions

A very simple, ultra-sensitive and fairly selective new spectrophotometric method has been developed for the rapid determination of lead(II) at ultra-trace level using 1,5-diphenylthiocarbazone (dithizone) in presence of aqueous micellar solutions. The proposed method enabled the determination of lead down to µg l−1in human blood and urine in aqueous media without resource of any “clean-up” step. The most remarkable point of this method is that the presence of micellar system avoids the previous steps of solvent extraction and reduces the cost, toxicity while enhancing the sensitivity, selectivity and the molar absorptivity. The complex formation of lead in blood with dithizone was completed within a minute at room temperature and the absorbance remains stable for 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 3.99×105l mol−1 cm−1and 30 ng cm−2of Pb, respectively. Linear calibration graphs were obtained for 0.06–60 mg l−1of PbII; the stoichiometric composition of the chelate is 1:2 (Pb:dithizone). The interference from over 60 cations, anions and complexing agents has been studied at 1 mg l−1of PbII. The method was successfully used in the determination of lead in several biological samples (human blood and urine and bovine liver), solution containing both lead(II) and lead(IV) and complex synthetic mixtures. The results of biological analyses by the spectrophotometric method were in excellent agreement with those obtained by AAS. The results of lead concentration in biological samples were varied with age, sex and place which have been discussed.

Determination of lead in biological samples by high-resolution continuum source graphite furnace atomic absorption spectrometry with direct solid sampling

Direct solid sampling is an attractive alternative for the determination of lead in biological samples, since it requires almost no sample preparation and provides higher sensitivity as no dilution is employed. In addition, the time required for the analysis and the risk of analyte loss or contamination during sample pre-treatment are reduced, the latter being the main problem associated with the usual digestion and dissolution procedures. In the present work, treating the determination of Pb in biological samples at 217.001 nm with solid sampling graphite furnace atomic absorption spectrometry (GF AAS), it will be shown that high-resolution continuum source AAS (HR-CS AAS) provides a variety of new possibilities for method development that have been unavailable previously. The use of ruthenium as a permanent modifier allowed a pyrolysis temperature of 900 °C to be applied, which was sufficient to eliminate the continuous background that preceded the analyte signal due to incomplete elimination of the matrix when lower pyrolysis temperatures were used. At atomization temperatures higher than 1500 °C, background absorption with pronounced fine structure followed the atomic signal. This was due to the electron excitation spectrum of PO, as was demonstrated by applying a least-squares background correction algorithm using the spectrum obtained by vaporization of (NH4)2HPO4 as a reference. Under optimum conditions, interference-free determination could be carried out by setting integration limits adjusted to integrate only the atomic signal; calibration against aqueous standards was performed and compared with calibration against a solid certified reference material (CRM). A total of seven biological CRM were analyzed (bovine muscle, pig kidney, lobster hepatopancreas, human hair, dogfish liver, oyster tissue and bovine blood), and the determined concentration of Pb was in agreement with the certified values using both calibration procedures, according to the t-test for a 95% confidence level. The detection limit (3s, n = 10) was 0.01 μg g−1, and the precision was typically better than 10%. The method is therefore adequate because of its simplicity, high sensitivity, good accuracy and wide applicability.

Cloud point extraction for the determination of cadmium and lead in biological samples by graphite furnace atomic absorption spectrometry

The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of Cd and Pb from digested biological samples. After complexation with O,O-diethyldithiophosphate (DDTP) in hydrochloric acid medium, the analytes are quantitatively extracted to the phase rich in the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) after centrifugation. Methanol acidified with 0.1 mol L −1 HNO 3 was added to the surfactant-rich phase prior to its analysis by electrothermal atomic absorption spectrometry (ET AAS). The adopted concentrations for DDTP, Triton X-114 and hydrochloric acid were all optimized. Pyrolysis and atomization temperatures were optimized using the extracts and pyrolysis temperatures of 700 °C for both elements and atomization temperatures of 1400 and 1600 °C for cadmium and lead, respectively, were used without adding any modifier, which shows that considerable analyte stabilization is provided by the medium itself. A more detailed investigation was carried out to determine which components of the extract were responsible for the high thermal stability achieved and it revealed that the amount of DDTP added and the phosphorus content of the digested samples contributed significantly to this phenomenon. Detection limits (3 σ B) of 6 and 40 ng g −1, along with enrichment factors of 129 and 18 for Cd and Pb, respectively, were achieved. The proposed procedure was applied to the analysis of five certified biological reference materials after microwave-assisted acid digestion in a mixture of H 2O 2 and HNO 3. Comparison with certified values was performed for accuracy evaluation, resulting in good agreement according to the t-test for a 95% confidence level. The high efficiency of cloud point extraction to carry out the determination of the studied analytes in complex matrices was, therefore, demonstrated.

A flow injection online micelle-mediated preconcentration and separation procedure without phase separation coupled with electrothermal atomic absorption spectrometry for determination of trace lead in biological samples

A new flow injection online micelle-mediated preconcentration and separation procedure other than cloud point extraction was developed for electrothermal atomic absorption spectrometric (ETAAS) determination of trace lead in biological samples. The procedure involved the formation of the analyte-entrapped surfactant micelles by online merging of the analyte solution with an ammonium pyrrolidine dithiocarbamate (APDC) solution and a Triton X-114 solution sequentially, the adsorption of the resultant analyte-entrapped surfactant micelles onto a microcolumn packed with silica gel, and online elution of the adsorbed analyte with 50 µl of acetonitrile for ETAAS detection. The operations for the phase separation of the analyte-entrapped surfactant micelles from aqueous solution (such as heating, addition of salting-out agents, filtration or centrifugation) which was always required in conventional cloud point extraction was avoided in the developed methodology, facilitating the online combination of the micelle-mediated preconcentration with a flow injection system. With consumption of 2.2 ml sample solution, a detection limit of 44.6 ng l−1, and a concentration factor of 22.5 were obtained at a sample throughput of 30 samples h−1. The precision (RSD) for 11 replicate measurements of 1 µg l−1 Pb was 2.9%. The developed methodology was successfully applied to the determination of trace lead in several certified biological reference materials.

Determination of cadmium and lead in biological samples by Zeeman ETAAS using various chemical modifiers

The electrothermal atomic absorption spectrometric determination of cadmium and lead in biological certified reference materials (CRMs) has been carried out by using NH 4H 2PO 4, Ni, Pd, Ni+NH 4H 2PO 4, Pd+NH 4H 2PO 4 and Ni+Pd+NH 4H 2PO 4 as chemical modifiers. A comprehensive comparison was made among the modifiers in 1% Triton X-100 plus 0.2% nitric acid as diluent and without modifier. Zeeman background correction and graphite tubes inserted with platforms were used. Comparison was made in terms of pyrolysis and atomization temperatures, atomization and background absorption profiles. Ni+Pd+NH 4H 2PO 4 modifier mixture was found to be preferable for the determination of Cd and Pb. Pyrolysis temperatures of analytes were increased up to 900 °C for Cd and 1250 °C for Pb by using Ni+Pd+NH 4H 2PO 4 in 1% Triton X-100 plus 0.2% nitric acid diluent solution. Biological CRMs were analyzed to verify the accuracy and precision of this method. Depending on the biological sample type, the percent recoveries were increased from 62 to 102% for Cd and from 58 to 106% for Pb by using the proposed modifier mixture. The detection limits of Cd and Pb were found to be 0.04, 0.92 μg l −1, respectively.

Direct determination of lead in biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) after furnace-fusion in the sample cuvette-tungsten boat furnace.

The newly conceived electrothermal vaporization (ETV) system using a tungsten boat furnace (TBF) sample cuvette was designed for the direct analysis of solid samples with detection by inductively coupled plasma mass spectrometry (ICP-MS). Into this small sample cuvette, a solid mixture of the biological samples and diammonium hydrogenphosphate powder as a fusion flux was placed and situated on a TBF. Tetramethylammonium hydroxide solution was added to the mixture. After the on-furnace digestion had been completed, the analyte in the cuvette was vaporized and introduced into the ICP mass spectrometer. The solid samples were analyzed by using a calibration curve prepared from the aqueous standard solutions. The detection limit was estimated to be 5.1 pg of lead, which corresponds to 10.2 ng g(-1) of lead in solid samples when a prepared sample amount of 1.0 mg was applied. The relative standard deviation for 8 replicate measurements obtained with 100 pg of lead was calculated to be 6.5%. The analytical results for various biological samples are described.

Spectrophotometric determination of lead in biological samples with dibromo-p-methyl-methylsulfonazo

A new highly sensitive and selective chromogenic reagent, dibromo-p-methyl-methylsulfonazo (DBM-MSA), was studied for determination of lead. In 0.24 mol l−1 phosphoric acid medium, which greatly increases the selectivity, lead reacts with DBM-MSA to form a 1:2 blue complex which has a sensitive absorption peak at 642 nm. Under the optimal conditions, Beer's law was obeyed over the range 0–0.6 μg ml−1 Pb(II). The molar absorptivity and Sandell's sensitivity are 1.02×105 l mol−1 cm−1 and 0.00203 μg cm−2, respectively. The limit of quantification, limit of detection and relative standard deviations were found to be 7.30 and 2.21 ng ml−1 and 1.1%, respectively. It is found that, except for Ca(II) and Ba(II), all foreign ions studied do not interfere with the determination. The interference caused by Ca(II) and Ba(II) can be easily eliminated by prior extraction with potassium iodide-methylisobutylketone. The method has been applied to the determination of lead in some biological samples with satisfactory results.

Lead contamination in Uruguay.

Uruguay is a developing country of South America with about 3 million people, half of whom live in its principal city, Montevideo. This city has several lead pollution sources as emitting industries, most of them surrounded by residential neighborhoods, some still using lead pipes in drinking water systems of old buildings, and has areas of heavy traffic with cars that are still fueled with leaded gasoline. The toxic effects of this heavy metal are well known. Children are a very sensitive population and their early symptoms of intoxication are not always taken into account. Blood lead is a good indicator of recent exposure to lead influenced by inhalation and ingestion. The systematic data assessment of lead pollution and people exposure in Uruguay was not well known when the Department of Toxicology and Environmental Hygiene of the Faculty of Chemistry began to analyze lead in biological samples, first from exposed workers and next from children and the general population, including sensitive animal species like dogs. Several described studies were carried out analyzing for blood lead to assess lead uptake and to obtain reference values for Uruguayan populations. Since 1986, that Department is the only laboratory where blood lead analyses are done, and the analytical method has been controlled by an interlaboratory quality control program of the Ministry of Labour of Spain and confirmed by experts from the Laboratory of Occupational and Environmental Medicine of Lund, Sweden. Financial and technical support was obtained from Sweden (SAREC) and also from the University of the Republic of Uruguay. Uruguayan lead workers have always been the principally studied population because their lead exposure assessment as well as their health protection education is not always done properly. Uruguay has adopted ACGIH reference values (150 micrograms/m3 in total lead dust, 50 micrograms/m3 respirable lead dust, 300 micrograms/L blood), and the high blood lead levels indicate significant adverse health risks effects and show a lack adequate controls for working conditions. A surveillance of children living in the surroundings of lead processing factories and in different neighborhoods was conducted because no data were available for blood lead in children before 1992. Also, general populations living in those areas or in areas of heavy traffic were assessed. Blood lead levels were always compared with those of control populations sampled at the same time answering a questionnaire. Workplace influence as well as atmospheric, soil, and water pollution were always considered to explain the obtained results. Some studies were carried out in dogs as a sensitive population, showing their higher exposure. The described studies included internal and external quality controls for the analytical methods and data processing. All blood lead analyses were done by atomic absorption spectrometry (AAS) after adding complexing agent and extraction. Samples taken together with Swedish researchers were analyzed in Lund (Department of Occupational and Environmental Medicine University Hospital), at 283.3 nm after electrothermal atomization (ETA). There was good correlation (r = 0.96) among 28 samples shared between Montevideo and Lund laboratories. The authors recommend more systematic clinical examination of workers, children, and the general population to determine the potential health risks for Uruguayan populations so as to improve their health conditions and to officially recognize lead pollution as an environmental problem.

Determination of Copper, Cadmium and Lead in Biological Samples by Electrothermal Vaporization Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

Electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (ETV-ID-ICP-MS) was applied to the determination of Cu, Cd and Pb in several biological samples. The isotope ratios for each element in each analytical run were calculated from the peak areas of each isotope. Various chemical modifiers were tested to obtain the optimum signal of cadmium and palladium was selected. The pyrolytic graphite platforms of the graphite tubes were then pretreated with palladium by three different methods, thermal pretreatment, electroplating and sputtering, and after careful evaluation of the analytical performance of these methods, thermal pretreatment of the platform with Pd before each analysis was selected. The ETV-ID-ICP-MS method was applied to the determination of Cu, Cd and Pb in dogfish liver reference material DOLT-1, dogfish muscle reference material DORM-1 and freeze-dried urine standard reference material NIST SRM 2670. The results agreed satisfactorily with the certified values.