Certified Reference Material BCR Research Articles

Evaluation of Environmental and Nutritional Aspects of Bee Pollen Samples Collected from East Black Sea Region, Turkey, via Elemental Analysis by ICP-MS.

Honeybee pollens are good food sources in terms of their mineral contents and are specific to the regions they are collected. In addition, they may be used as bioindicators in the assessment of environmental pollution based on their potentially toxic element contents. In the present study, mineral element composition and potentially toxic element levels of honeybee pollen samples collected from various cities in East Black Sea Region of Turkey (18 samples) were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave assisted acid digestion. The method validation was performed by using CRM (Certified Reference Material-BCR®279-Sea Lettuce-Ulva lactuca) to evaluate the accuracy and precision. Elemental composition of honeybee pollens were detected within the following ranges (minimum-maximum, mg kg-1 dry pollen); Mn (manganese): 11.579-117.349, Fe (Iron): 34.865-811.043, Zn (zinc): 17.707-56.223, Se (selenium): 0.422-0.722, Cr (chromium): 0.848-6.949, Cu (copper): 7.510-26.344, Mg (magnesium): 549.921-2149.716, Ca (calcium): 726.575-2201.837, Na (sodium): 36.518-120.283, Pb (lead): < 0.005-0.622, Cd (cadmium): 0.039-1.390, Ni (nickel): 2.317-21.710, and As (arsenic): 1.331-2.248. Recommended daily allowance, target hazard quotients, hazard index, and carcinogenic risk values of the pollens were calculated with the help of these results. In considering THQ values, pollens were determined to be safe for the consumption of both genders. Based on the carcinogenic risk calculation, most of the pollens examined in this study were categorized as moderately risky. Monitoring studies can be used to identify new sources of contamination or the origin and spread of a particular element. Hence, bee pollens can also be considered as potential bioindicators of toxic metal pollution. HIGHLIGHTS: • Mineral content and potentially toxic metal levels of 18 honeybee pollens were determined. • Recommended daily allowance (RDA) values were calculated. • The nutritional aspects of honeybee pollen samples were evaluated. • Hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) estimation of honeybee pollens were assessed. • The potentiality of honeybee pollens as a bioindicator for pollution was discussed.

Determination of Metals in Walnut Oils by Means of an Optimized and Validated ICP-AES Method in Conventional and Organic Farming Type Samples

Agricultural products are indispensable for equilibrated diets since they discharge minerals and several bioactive constituents. Considering the increasing demand for organic products, research has been conducted over recent years to investigate whether organically grown food products are chemically different compared to those produced with conventional farming. In this work, a novel inductively coupled plasma atomic emission spectrometric method was developed and validated for the determination of nutrient and toxic elements in walnut oils produced with conventional and organic farming. The method presented good linearity (r2 &gt; 0.9990) for each element at the selected emission line. The limits of detection and limits of quantification ranged between 0.09 μg g−1 to 2.43 μg g−1 and 0.28 μg g−1 to 8.1 μg g−1, respectively. Method accuracy and was assessed by analyzing the certified reference materials BCR 278-R and spiked walnut oil samples. The determined metals were quantified, and the results were analyzed by Student’s t-test to investigate the differences in the elemental profile of the walnut oils according to type of farming (conventional or organic).

Comparison of two non-specific flow-through sequential extraction approaches to identify the physico-chemical partitioning of potentially harmful elements in a certified reference material

Two non-specific sequential extraction methods utilising chemometric data processing (chemometric identification of substrates and element distribution, CISED) have been developed and used to determine the physico-chemical partitioning of potentially harmful elements (PHE) in certified reference material BCR CRM 701 (lake sediment). A miniaturized centrifugation method in which the sample was extracted on a filter insert in a polypropylene centrifuging tube, and a quasi-flow through method in which the sample was supported on a TX40 filter in a 47 mm in-line polycarbonate filter holder, gave similar results. The CISED data processing identified nine components. Seven of these were of geochemical origin – two carbonate components, an Al/Fe oxide/hydroxide component, three Fe-dominated components and one Si-dominated component – while the others represented the TX40 filter blank. The overall extraction capabilities of the methods were similar to that of the well-established BCR sequential extraction (Σsteps 1–3). However, whilst the BCR extraction is operationally defined, the CISED provides information on associations between PHE and the geochemical components identified. The flow through CISED procedure has potential applications in investigating the chemical speciation of PHE associated with urban airborne particular matter.

In situ ultrasound-assisted preparation of Fe3O4@MnO2 core-shell nanoparticles integrated with ion co-precipitation for multielemental analysis by total reflection X-ray fluorescence

In this work, a new analytical approach based on in situ ultrasound-assisted preparation of manganese dioxide coated magnetite nanoparticles (Fe3O4@MnO2 NPs) was applied for extraction and preconcentration of Ni, Cu, Zn, Tl, Pb, Bi and Se. The Fe3O4@MnO2 core-shell nanocomposite was synthesized by application of high-intensity sonication to an aqueous reaction medium in the presence of the target analytes, which are trapped during NPs formation. In this way, synthesis of the nanosorbent and extraction can be simultaneously accomplished within only 30s. After the extraction step, the resulting Fe3O4@MnO2 NPs enriched with the target analytes were separated by an external magnetic field, so that filtration or centrifugation steps were unnecessary. A 10μL aliquot of the solid phase was deposited onto a sample carrier (quartz reflector) and directly analyzed by total-reflection X-ray fluorescence (TXRF) without the need for an elution step. A comprehensive characterization of the Fe3O4@MnO2 NPs was carried out by transmission electron microscopy and TXRF. Detection limits ranged from 0.19 to 0.98μgL−1 depending on the analyte. Enrichment factors in the range of 402–540 were obtained. The repeatability expressed as relative standard deviation was around 1.7% (N=5). The accuracy of the proposed method was assessed by analyzing the certified reference material BCR®-610 (groundwater). An effective, simple, rapid and sensitive procedure for multielemental analysis of water samples was accomplished.

Evaluation of ammonium fluoride for quantitative microwave-assisted extraction of silicon and boron from different solid samples

A novel, simple, efficient and environmentally friendly closed-microwave-assisted extraction (MAE) method of silicon and boron from a variety of industrial and environmental samples using ammonium fluoride as an extractant was developed. This method avoids handling the corrosive and toxic HF and prevents the potential risk of analyte loss due to the creation of volatile SiF4 and BF3 in the presence of HF. Atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry were employed for the subsequent analysis of the resulting supernatant for determination of Si and B, respectively. Certified reference material BCR®-032 Natural Moroccan Phosphate Rock (phosphate fertiliser) was taken to optimise the extraction parameters such as the sample amount, extraction temperature and time and the volume of the extractant. The optimum extraction parameters evaluated using a fractional factorial design were as follows: 50 mg of the sample extracted with 5 mL of 100 g L−1 NH4 F for 15 min at 180°C. The optimised MAE procedure was successfully applied to nine different matrix reference materials intended primarily for validation of methods for determination of components in fertilisers, sludge, plants and fly ash. The obtained results were in a good agreement with the certified or comparative values with an overall precision better than 10% in all cases. The proposed method is recommended for fast and reliable preparation of samples with silicon content <8.2% (w/w). However, further decreasing the sample mass to 10 mg enabled the quantitative extraction of silicon from fly ashes at levels of 23% (w/w).

Synthesis and characterization of a nanomagnetic ion imprinted polymer for selective extraction of silver ions from aqueous samples

A magnetic ion imprinted polymer (mag-IIP) for the selective extraction of silver ions was synthesized by using functionalized magnetite (Fe3O4) nanoparticles as the magnetic core, silver ion as the template, salen as the ligand, 4-vinylpyridine as the functional monomer, and ethylene glycol dimethacrylate as the cross linker. A magnetic non-imprinted polymer was also prepared by an analogous procedure. The mag-IIP was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, thermal analysis and scanning electron microscopy. The silver ions retained by the mag-IIP were eluted using the thiourea solution at a pH of ~3 and then determined by the flame atomic absorption spectrometry. The conditions for the extraction and preconcentration were optimized. The maximum sorption capacity of the mag-IIP is 28.2 mg g−1 of Ag(I) ions. When preconcentrating a 150 mL sample, the enhancement factor is 293, and the detection limit is 50 ng L−1. The method was successfully applied to the determination of silver ions in (spiked) water samples and in the certified reference materials BCR 288 and CPB-1.

Application of high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC–ICP-MS) for determination of chromium compounds in the air at the workplace

The toxicity and bioavailability of chromium species are highly dependable on the form or species, therefore determination of total chromium is insufficient for a complete toxicological evaluation and risk assessment. An analytical method for determination of soluble and insoluble Cr (III) and Cr (VI) compounds in welding fume at workplace air has been developed. The total chromium (Cr) was determined by using quadruple inductively coupled plasma mass spectrometry (ICP-MS) equipped with a dynamic reaction cell (DRC(®)). Soluble trivalent and hexavalent chromium compounds were determined by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A high-speed, reversed-phase CR C8 column (PerkinElmer, Inc., Shelton, CT, USA) was used for the speciation of soluble Cr (III) and soluble Cr (VI). The separation was accomplished by interaction of the chromium species with the different components of the mobile phase. Cr (III) formed a complex with EDTA, i.e. retained on the column, while Cr (VI) existed in the solutions as dichromate. Alkaline extraction (2% KOH and 3% Na2CO3) and anion exchange column (PRP-X100, PEEK, Hamilton) were used for the separation of the total Cr (VI). The results of the determination of Cr (VI) were confirmed by the analysis of the certified reference material BCR CRM 545 (Cr (VI) in welding dust). The results obtained for the certified material (40.2±0.6 g kg(-1)) and the values recorded in the examined samples (40.7±0.6 g kg(-1)) were highly consistent. This analytical method was applied for the determination of chromium in the samples in the workplace air collected onto glass (Whatman, Ø 37 mm) and membrane filters (Sartorius, 0.8 μm, Ø 37 mm). High performance liquid chromatography with inductively coupled plasma mass spectrometry is a remarkably powerful and versatile technique for determination of chromium species in welding fume at workplace air.

Validation and applications of a GC-ECD method for the determination of polychlorinated biphenyls in fish and seafood

This work illustrates how a well-optimized gas chromatograph-electron capture detector method represents an economical and satisfactory analytical choice for the routine determination of polychlorinated biphenyls (PCBs) of US Environmental Protection Agency concern in fish and seafood. A dramatic and never observed dependence of the recovery efficiency of PCB congeners on the temperature of activation of the sorbent phase prompted us to optimize both the key steps (extraction and cleanup) of the analytical procedure. Very high performance levels in terms of the limit of detection (less than 0.64 ng g−1) and precision [better than 15 % for unspiked and spiked samples of gilt-head bream, Sparus aurata, and better than 20 % for certified reference material BCR 350 (mackerel oil)] were obtained. The acceptability of accuracy data was successfully evaluated according to the Association of Official Analytical Chemists' guidelines. The method was tested by analyzing ten samples of aquacultured gilt-head bream from Greece and Italy. The total of 18 PCBs measured for each sample ranged from 120.1 to 335.5 ng g−1 (average value 180.7 ng g−1) on a fat weight basis.

Comparison of Two Analytical Methods for the Analysis of Methylmercury in Fish

In this study, we compared a high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method and an isotope dilution gas chromatography mass spectrometry (ID-GC-MS) method for the analysis of methylmercury (MeHg) in fish samples. Using HPLC-ICP-MS, the limit of detection (LOD) was 2.0 ngHg · g−1 for inorganic Hg and was 5.0 ngHg · g−1 for MeHg. In comparison, the LOD for MeHg was 3.4 ngHg · g−1 for using ID-GC-MS. Certified reference material (CRM) results agreed well with certified values for both methods. The mean recovery for analysis of CRM BCR 463 by HPLC-ICP-MS was 99 ± 2.1 % for MeHg and was 103 ± 2.1 % for total Hg. Two CRMs, BCR 463 and CRM DORM2, were analyzed by ID-GC-MS, the mean recovery of MeHg was 87 ± 1.9 % for BCR 463, and the mean recovery of MeHg was 102 ± 2.9 % for CRM DORM2. Matrix samples spiked with Hg or MeHg at various concentrations were analyzed by two methods. For HPLC-ICP-MS method, the mean recovery for MeHg spiked samples was 93 ± 4.2 %. For ID-GC-MS method, the mean recovery for MeHg spiked samples was 91 ± 5.2 %. A total of 19 predatory fish and 54 tuna fish samples were analyzed using both methods. No significant difference was observed between the MeHg data generated from both methods. The average relative standard deviation (RSD) between the two datasets for 19 predatory fish samples was 8.8 %. The average RSD between two datasets for 54 tuna fish samples was 4.4 %.The HPLC-ICP-MS method offers substantial advantages over the method of ID-GC-MS because the former method can determine the total mercury (Hg) and MeHg in a single chromatographic run and the analysis time is much shorter. The latter method is time consuming due to overnight digestion and having to conduct presample analysis for signal-matched isotope dilution spiking and requires more expensive isotope labeled reagents.

Determination of Some Trace Elements in Food and Soil Samples by Atomic Absorption Spectrometry After Coprecipitation with Holmium Hydroxide

The determination of trace elements in food and soil samples by atomic absorption spectrometry was investigated. A coprecipitation procedure with holmium hydroxide was used for separation-preconcentration of trace elements. Trace amounts of copper(II), manganese(II), cobalt(II), nickel(ll), chromium(lll), iron(Ill), cadmium(ll), and lead(ll) ions were coprecipitated with holmium hydroxide in 2.0 M NaOH medium. The optimum conditions for the coprecipitation process were investigated for several commonly tested experimental parameters, such as amount of coprecipitant, effect of standing time, centrifugation rate and time, and sample volume. The precision, based on replicate analysis, was lower than 10% for the analytes. In order to verify the accuracy of the method, the certified reference materials BCR 141 R calcareous loam soil and CRM 025-050 soil were analyzed. The procedure was successfully applied for separation and preconcentration of the investigated ions in various food and soil samples. An amount of the solid samples was decomposed with 15 mL concentrated hydrochloric acid-concentrated nitric acid (3 + 1). The preconcentration procedure was then applied to the final solutions. The concentration of trace elements in samples was determined by atomic absorption spectrometry.

Spectrophotometric Determination of Mercury in Water Samples After Preconcentration Using Dispersive Liquid–Liquid Microextraction

A simple method for the determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction is described. The procedure is based on the extraction of mercury in the form of a complex and its subsequent determination by spectrophotometry. The complex is formed between Hg(II) and 2-(2-benzothiazolylazo)-p-cresol. The detection at 650 nm is performed directly in the metal-rich phase, which is spread on a triacetylcellulose membrane. The method eliminates the need to use a cuvet or large quantities of samples and reagents. The parameters that influence the preconcentration were studied, and the analytical characteristics were determined. The enrichment factor and the consumptive index for this method were 64 and 0.16 mL, respectively. The LOD (3.3 microg/L) and LOQ (11.1 microg/L) were also determined. The accuracy of the method was tested by the determination of mercury in certified reference materials BCR 397 (Human Hair) and SRM 2781 (Domestic Sludge). The method was applied to the determination of mercury in samples of drinking water, sea water, and river water.

Determination of cobalt, nickel and iron at trace level in natural water samples by in-column chelation-reversed phase high-performance liquid chromatography

This paper reports the utilization of 4-(2-pyridylazo) resorcinol (PAR) as a chelating reagent for in-column derivatization and the determination of trace Co, Fe, and Ni ions by reversed-phase high-performance liquid chromatography with photodiode array detector. A good separation of Co, Fe, and Ni chelates were achieved by using an Inertsil ODS-3 column and a mobile phase, consisted of methanol-THF-water mixture (50:5:45) containing ammonium acetate buffer (pH 5.0) and PAR. After full optimization, good repeatability of retention times (relative standard deviation (RSD) < 0.05%) and peak areas (RSD < 1.7%) was achieved as well as a good linearity (r (2) > 0.9991). The detection limits (S/N = 3), expressed as micrograms per liter, were 0.50 (Co), 9.07 (Fe), and 2.00 (Ni). The applicability and the accuracy of the developed method were estimated by the analysis of spiked water samples and certified reference material BCR 715 wastewater-SRM.

The use of cation exchange matrix separation coupled with ICP-MS to directly determine platinum group element (PGE) and other trace element emissions from passenger cars equipped with diesel particulate filters (DPF)

Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation method detection limits of 1.6 ng g(-1) for Pd, 0.4 ng g(-1) for Rh and 4.3 ng g(-1) for Pt were achieved, the method was validated against the certified reference material BCR 723, urban road dust. The test vehicle was fitted with new and aged catalytic converters with and without diesel particulate filters (DPF). Samples were collected after three consecutive New European Driving Cycle (NEDC) of the particulate and "soluble" phases using a home-made sampler optimised for trace element analysis. Emission factors for the PGEs ranged from 0.021 ng km(-1) for Rh to 70.5 ng km(-1) for Pt; when a DPF was fitted, the emission factors for the PGEs actually used in the catalysts dropped by up to 97% (for Pt). Trace element emission factors were found to drop by a maximum of 92% for Ni to a minimum of 18% for Y when a DPF was fitted; a new DPF was also found to cause a reduction of up to 86% in the emission of particulate matter.

Simultaneous measurement of phosphorus and platinum by Size Exclusion Chromatography coupled to Inductively Coupled Plasma Mass Spectrometry (SEC-ICPMS) using xenon as reactive collision gas for characterization of platinum drug liposomes

Liposomes have attracted intensive attention as drug delivery systems in anti-cancer therapy. Since liposomes are constructed by self-assembling of phospholipids, ICP-MS is a suitable method for simultaneous determination of liposomes and encapsulated metallic drug substances such as platinum-based drugs. An efficient method for simultaneous determination of phosphorus and platinum in liposome samples has been established based on the use of xenon as a collision gas in DRC-ICP-MS. Under the optimum conditions with respect to signal to noise ratio, the interferences were suppressed and the detection limits of phosphorus and platinum were 0.3 and 0.05 ng mL−1, respectively. Quality control was performed by using a certified reference material BCR 273 and biological reference materials. For the purpose of investigation of liposome stability and metallo-drug release from liposomes, a hyphenated method based on size exclusion chromatography was developed for separation of free and encapsulated platinum in a model liposome formulation of oxaliplatin. Moreover, an accelerated drug release study was performed by sonication of liposomal samples and using the developed hyphenated method to determine the drug leakage. It has been demonstrated that the SEC-DRC-ICP MS method was an efficient tool in the development and characterization of liposome based formulations of metallic drugs.

Comparison of Different Extraction Approaches for Heavy Metal Partitioning in Sediment Samples

Three extraction methods, ultrasonic assisted extraction (USE), microwave assisted extraction (MSE), and conventional single extraction (CSE), in conjunction with the modified three-stage BCR sequential extraction procedure (SEP) were applied to examine the contents of Cd, Cu, Cr, Ni, Pb and Zn from lake sediment samples, to know whether these techniques can reduce extraction time and improve reproducibility. The SEP and developed alternative single extraction methods were validated by the analysis of certified reference material BCR 601. By the use of optimized sonication and microwave conditions, steps 1, 2 and 3 of the BCR sequential extraction methods (excluding the hydrogen peroxide digestion in step 3, which was not performed with sonication and microwave) could be completed in 15–30 min and 60– 150 s, respectively. The recoveries of total extractable metal contents in BCR 601, obtained by three single extractions ranged from 93.3%–102%, 88.9%–104% and 81.2%–96.2% for CSE, USE and MSE, respectively. The precision of the single extraction methods was found in the range of 3.7%–9.4% for all metals ( n = 6).

Simple and selective extraction process for chromium (VI) in industrial wastewater

A simple and relatively green method has been developed for the determination of chromium based on the extraction of chromium (VI) as its ion-association complex with tetrabutylammoniumiodide (TBAI) in acidic medium. The ion-pair is extracted using isobutylmethylketone (MIBK) as the solvent. The concentration of the extracted chromium (VI) in the organic layer was measured spectrophotometrically at a wavelength maximum of 366 nm and the organic layer was characterized using FT-IR spectroscopy. The influence of various analytical parameters such as pH, aqueous phase volume, equilibration time, interfering ions etc. has been studied in detail. The extracted chromium (VI) was back extracted into the aqueous phase to the non-toxic chromium (III) using ascorbic acid. The calibration graph was linear in the range of 0–2 μg mL −1 chromium (VI) with a relative standard deviation of 2.4%. A detection limit of 0.25 μg in 25 mL aqueous phase volume could be achieved and the validity of the proposed method has been checked by applying it to synthetic mixtures, spiked water sample, electroplating wastewater and certified reference material BCR ®-715.

Arsenic fractionation in sediments of different origins using BCR sequential and single extraction methods

The arsenic (As) contaminated sediment serves as a long-term source of arsenic because its mobility and transport in the environment are strongly influenced to associated solid phase. A single extraction method based on the reagents employed in the BCR three steps sequential extraction scheme (BCR-SES) for partitioning of arsenic (As) in sediment samples has been developed. The single-step extraction enabled a reduction of extraction times, yielding extractable contents in accordance with those obtained by application of the BCR-SES, which can be regarded as a standard method and validated by using certified reference material BCR 701. The extractable As content associated with different phases in sediment samples were analysed by electrothermal atomic absorption spectrophotometer. The extraction efficiency of As by single-step extraction was slightly higher than BCR-SES, ranged (100–104%), while difference was not significant at 95% confidence limit with <10% precision. The sediment samples from different origins varied in their physico-chemical properties and total As content. The relative mobility of As obtained from different origins was found in increasing order as: acid soluble fraction < oxidizable fraction < reducible fraction. The acid soluble fraction of As was higher in lake sediment samples as compared to those of canal and river sediments, indicating the contamination of lake ecosystem.

Application of methods (sequential extraction procedures and high-pressure digestion method) to fly ash particles to determine the element constituents: A case study for BCR 176

Sequential extraction procedures and the high-pressure digestion method were selected to determine the element constituents of fly ash samples. Sequential extraction is one of the most useful methods used to measure the various elements from municipal solid waste incineration ash and contaminated soils. The extract from each step is analyzed using various techniques and equipments, and the results are then evaluated. In this work, a six-step extraction procedure modified from that of Tessier et al. and Wang et al. was performed and applied to the certified reference material BCR 176 (city waste incineration ash). Analyses were carried out by various techniques such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma-mass spectrometry (ICP-MS), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), and X-ray powder diffraction (XRPD) to evaluate the characteristics of fly ash. The extraction efficiency of many elements was higher than 80%, and the relative standard deviations (RSD) for recovery of most elements were within 10%. In addition, an H 2O 2 + HNO 3 + HF mixed acid digestion solution processed using a low-temperature evaporation procedure was selected as the optimal process for fly ash digestion. The results of this work provide information on the chemical composition, distribution, and potential mobility of the investigated elements.

Sensitive Mercury Speciation by Reversed-Phase Column High-Performance Liquid Chromatography with UV-Visible Detection After Solid-Phase Extraction Using 6-Mercaptopurine and Dithizone

A highly selective and sensitive method was developed for preconcentration of inorganic and organic mercury compounds followed by reversed-phase column high-performance liquid chromatography (RP-HPLC) with UV-visible detection. The method was based on the reaction of mercury with 6-mercaptopurine and solid-phase extraction (SPE) of the complex on an octadecylsilane (C18) cartridge. The complex was then treated with ammoniacal dithizone solution, and the complexes of inorganic and organic mercury with dithizone were eluted by methanol. The speciation analysis of methylmercury (MeHg), phenylmercury (PhHg), and inorganic Hg (II) was carried out by RP-HPLC. Some experimental variables that influence the SPE and derivatization, such as pH, chelating and derivatizing agent concentration, and surfactant addition, were investigated. The calibration graphs of MeHg, PhHg, and Hg (II) were linear [correlation coefficient (r) > 0.999] from the detection limits (0.12, 0.16, and 0.14 ng) to 8.5, 6.0, and 6.7 ng Hg, respectively. By applying the SPE procedure, a 100-fold concentration of the sample was obtained. The procedure was applied to sea water and tuna fish samples. The method's accuracy was investigated by using tuna fish certified reference material BCR 464 and by spiking the samples with different amounts of MeHg, PhHg, and Hg (II). The average recoveries of MeHg, PhHg, and Hg (II) from spiked samples (0.1-2.0 microg/L Hg) were 96 +/- 4, 98 +/- 3, and 104 +/- 4%, respectively.

Ultrasound-Assisted Pseudodigestion for Toxic Metals Determination in Fish Muscles Followed by Electrothermal Atomic Absorption Spectrophotometry: Multivariate Strategy

A simple and efficient procedure for the determination of arsenic (As), cadmium (Cd), and lead (Pb) in the edible parts of freshwater fish by ultrasonic-assisted acid pseudodigestion (USD) was developed. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of several variables at once. Five variables--sonication time, sample mass of muscle tissue, temperature of the ultrasonic bath, mL of nitric acid, and mL of a mixture of acid and oxidant--were regarded as factors. From these studies, certain variables showed up as significant, and they were optimized by a 23+star central composite design, which involved 16 experiments. Optimum values of the variables were selected for the development of USD to determine the contents of As, Cd, and Pb in fish muscles used as pollution bioindicators from Lake Manchar (Sindh, Pakistan). The determination of the 3 toxic metals under study was performed by electrothermal atomic absorption spectrometry. The accuracy of the optimized procedure was evaluated by analysis of certified reference materials BCR 185R bovine liver and by comparison with conventional wet acid digestion methodology. The result obtained by the optimized method showed good agreement with the certified values and sufficiently high recovery. No significant differences were observed for P = 0.05. Relative standard deviation values (average of 10 separate determinations) were 1.21, 5.52, and 5.32% for As, Cd, and Pb, respectively.