Determination of Mo, Zn, Cd, Ti, Ni, V, Fe, Mn, Cr and Co in crude oil using inductively coupled plasma optical emission spectrometry and sample introduction as detergentless microemulsions

A procedure to prepare crude oil samples as detergentless microemulsions was optimized and applied for the determination of Mo, Zn, Cd, Si, Ti, Ni, V, Fe, Mn, Cr and Co by ICP OES. Propan-1-ol was used as a co-solvent allowing the formation of a homogeneous and stable system containing crude oil and water. The optimum composition of the microemulsion was crude oil / propan-1-ol / water / concentrated nitric acid, 6 / 70 / 20 / 4 w/w/w/w. This simple sample preparation procedure together with an efficient sample introduction (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber) allowed a fast quantification of the analytes using calibration curves prepared with analyte inorganic standards. In this case, Sc was used as internal standard for correction of signal fluctuations and matrix effects. Oxygen was used in the nebulizer gas flow in order to minimize carbon building up and background. Limits of detection in the ng g^− 1 range were achieved for all elements. The methodology was tested through the analysis of one standard reference material (SRM NIST 1634c, Residual Fuel Oil) with recoveries between 97.9% and 103.8%. The method was also applied to two crude oil samples and the results were in good agreement with those obtained using the acid decomposition procedure. The precision (n = 3) obtained was below 5% and the results indicated that the method is well suited for oil samples containing low concentrations of trace elements.     

Dual gradient LC method for the determination of pharmaceutical residues in environmental samples using a monolithic silica reversed phase column

Detailed below is a simple reversed-phase liquid chromatography (RP-LC) method for the simultaneous separation of up to 21 acidic, basic, and neutral pharmaceuticals using Merck Chromolith Performance RP-C18e monolithic columns with direct ultraviolet (UV) absorption detection. By simultaneously applying a solvent elution gradient program with a mobile phase flow gradient, both a decrease in the overall analysis time and a general increase in peak efficiencies were observed. Mobile phase pH and buffer concentration were optimised using the overall resolution product under applied gradient conditions. Under optimised conditions peak area reproducibility (n?=?6) ranged between 0.4 and 9.3%, determined at the method LOQ level. For real sample analysis pharmaceutical residues were extracted using an optimised solid phase extraction (SPE) procedure, utilising Strata-X extraction cartridges, which overall provided the highest relative recovery data in comparison with four other commercially available SPE sorbents (17 out of 20 residues investigated had recoveries over 70%). Complete method precision, including all sample pre-treatment and LC analysis for six spiked river water samples at the 1 and 2?µg?L^?1 level was between 10 and 29%. Using 1?L volumes of 1?µg?L^?1 spiked estuarine water samples, the majority of detection limits were found to be in the 10–50?ng?L^?1 range.     

Gas chromatographic determination of carbonyl compounds in biological and oil samples by headspace single-drop microextraction with in-drop derivatisation

A suitable method for the gas chromatographic determination of 10 characteristic carbonyls in biological and oil samples based on the in-drop formation of hydrazones by using 2,4,6-trichlorophenylhydrazine (TCPH), has been developed. The derivatisation-extraction procedure was optimized separately for aqueous and oil samples with respect to the appropriate organic drop solvent, drop volume, in-drop TCPH concentration, sample stirring rate, temperature during single-drop microextraction (SDME), reaction time and headspace-to-sample volume ratio. The optimization showed differentiation of optimum values between the studied matrices. The limits of detection were found to range from 0.001 to 0.003 μg mL⁻¹ for the aqueous biological samples and from 0.06 to 0.20 μg mL⁻¹ for the oil samples. The limits of quantification were in the range of 0.003-0.010 μg mL⁻¹ and 0.020-0.059 μg mL⁻¹ for aqueous and oil samples, respectively. The overall relative standard deviations of the within-day repeatability and between-day reproducibility were <4.4% and <8.2% for the aqueous biological samples and <3.9% and <7.4% for the oxidized oil samples.     

Optimization of the Sample Preparation Procedure for the Determination of Trace Elements in Auricularia auricula by Inductively Coupled Plasma-Optical Emission Spectrometry

This study aimed to develop a precise and accurate method of sample preparation of Auricularia auricula for inductively coupled plasma-optical emission spectrometry-based trace element determination and to compare concentrations of seven trace elements (Mg, Fe, Mn, Zn, Ni, Cr, Sr) in six A. auricula samples belonging to three varieties with two cultivation substrates. Five sample preparation procedures, microwave-assisted digestion, nitric acid digestion with hot plate heating, nitric acid and perchloric acid digestion with hot plate heating, nitric acid digestion with ash content, and aqua regia digestion with ash content, were compared. The performance of the procedures was determined based on the precision and accuracy of the results and the limits of detection of the elements. The best results, with limits of detection of 0.60–6.60?ng?·?mL^?1 and recoveries for spiked samples between 93.80 and 105.00%, were found using nitric acid digestion with ash content. Six A. auricula samples were analyzed using the proposed procedure. Among the tested elements, the concentration of Fe was highest in all six A. auricula samples up to a maximum concentration of 284.83?µg?·?g^?1. The concentrations of Mn, Cu, and Ni increased in mixed stands (basswood, birch, and mongolica) compared with pine sawdust cultivation.     

Comparison of sample preparation methods for the ICP-AES determination of minor and major elements in clarified apple juices

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of minor and major elements present in apple juices. Prior to ICP-AES measurement, samples were diluted with nitric acid or digested in a microwave assisted digestion system. The differences in the measured element concentrations after application of different types of sample preparation procedures are discussed. The direct measurement compared to closed microwave dissolution was found to be the best sample preparation procedure. Prior to the measurements the ICP-AES method was validated and optimized for the determination of elements in apple juices. For diluted apple juice samples the lowest limits of detection (LOD) were obtained for Ba and Cd (< 20 μg L^{− 1}), moderate ones for Cu, Mn, Ni, Fe, Ag, Ca, Cr, Zn, Mg, and Sr (20–100 μg L^{− 1}), and the highest LODs for K, Pb, Na, and Al (> 110 μg L^{− 1}). The results obtained for the repeatability (< 0.9%), the intermediate precision (< 4.5%), the day-to-day reproducibility (< 5.2%), and the overall uncertainty of measurement (approx. 4–7%) for all elements analyzed demonstrated the good applicability of the proposed method. Differences in major element content in fresh and commercial apple juice are discussed.     

Comparison of direct sampling and emulsion analysis using a filter furnace for the determination of lead in crude oil by graphite furnace atomic absorption spectrometry

The determination of trace elements in crude oil is difficult due to the complex nature of the sample and the various different chemical forms in which the metals can occur. The advantage of graphite furnace atomic absorption spectrometry is that only a minimum of sample pretreatment is required. In this work two techniques have been compared to establish a fast and reliable method for lead determination in crude oil. In the first one the crude oil samples were weighed directly onto solid sampling (SS) platforms and introduced into the graphite tube for analysis. In the second one the samples were prepared as oil-in-water emulsions and analyzed in a filter furnace (FF). Twenty μL of a mixture of 0.5 mg L^− 1 Pd + 0.3 mg L^− 1 Mg + Triton X-100 has been used as the modifier, and calibration against aqueous solutions has been used for both methods. The sensitivity obtained with the FF was more than a factor of two better than that with SS; however, as a larger sample mass could be introduced in the latter case, so that the limits of detection for both techniques were 0.004 mg kg^− 1. Seven crude oil samples were analyzed using the two procedures, and all results were in agreement at a 95% confidence level using a paired Student's t-test. For validation purposes, three crude oil samples have been mineralized using an open-vessel acid digestion, and the results were in agreement with those found with direct sampling and with emulsion sampling using FF according to ANOVA test. Both methods are simple, fast and reliable, being appropriated for routine analysis; however, the direct method using SS technology should be preferred because of its simplicity, speed and commercial availability.     

Ultrasound-assisted treatment of palm oil samples for the determination of copper and lead by stripping chronopotentiometry

The concentration of trace metals in vegetable oils is an important criterion for the assessment of oil qualities with regard to freshness, keeping properties, storage and their influence on human nutrition and health. In this work, an effective and simple method for the determination of copper and lead in palm oil by stripping chronopotentiometry (SCP) is proposed. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was coated with a thin mercury film. An ultrasonic bath was used for the extraction of copper and lead from eleven oil samples using a 1:1 (v/v) mixture of concentrated hydrochloric acid and hydrogen peroxide. Efficient extraction of copper and lead (∼ 100%) was attained after 60 min of ultrasonic pre-treatment. A good correlation between the amount of sample and the time necessary for complete liberation of the metals was observed. The accuracy of the method was evaluated by means of a reference sample of skim milk powder containing trace elements (BCR 151). Quantitative analysis was carried out by the method of standard additions. Good linearity was obtained in the range of the concentrations examined. Detection limits of 13 and 50 ng g^− 1 were found for Cu and Pb, respectively, in the palm oil samples. The average values found for the palm oil samples analyzed were in the range of < 0.013-2.67 µg g^− 1 for copper and < 0.050-1.82 µg g^− 1 for lead. The palm oil samples were also analyzed by graphite furnace atomic absorption spectrometry (GFAAS), demonstrating a very good correlation between the results.     

Optimization and validation of a Laser Ablation Inductively Coupled Plasma Mass Spectrometry method for the routine analysis of soils and sediments

A simple, rapid and sensitive method was developed for the routine analysis of trace elements on sediments and soils by UV-ns-LA-ICP-MS. The homogenization procedure that reduces the particle size of the samples to less than 1 µm diameter was found to be a key factor to allow for a representative sampling of the bulk soil at the micro-scale and to improve reproducibility and cohesion of the sample without requiring the use of any binder. The elimination of binders simplified the sample preparation and avoided any undesirable dilution of the sample. SEM/EDX analyses were conducted to evaluate the efficiency of laser to sample interaction. Matrix effects and different quantitation strategies were employed to demonstrate the utility of the analytical technique. Sixteen elements were analyzed on soil and sediment samples and certified reference materials. Analytical results obtained by LA-ICP-MS were comparable to solution ICP-MS analysis in terms of accuracy, precision and limits of detection. Two independent proficiency tests for trace metals in soils were conducted to compare the performance of the method versus conventional digestion ICP and AA methods, obtaining z scores ≤ 3 for all elements measured by LA-ICP-MS. An overall bias between 8 and 15% was found, depending on the sample while the overall precision was found to be better than 5% RSD for all samples. Limits of detection were as low as 0.01 mg kg^− 1.     

A new approach for determination of crustal and trace elements in airborne particulate matter

An ICP-OES procedure was developed for fast and accurate determination of various crustal (Al, Ca, Fe, Mg, Si) and trace elements (Ba, Cu, Mn, Na, K, Sr, Ti, Zn) in airborne particulate matter. The method is based on a preliminary treatment of the aerosol samples with a mixture of nitric acid and hydrogen peroxide at elevated temperature leading to a mineralization of the organic sampling substrate, dissolution of soluble material and homogeneous suspension of the remaining non-soluble fraction. After dilution the derived slurry solutions were measured using ICP-OES. The reproducibility of analysis given as the relative standard deviation (% RSD) varied between 3.2 and 6.8% for bulk constituents such as Al, Ca, Fe, Mg and Si whereas values ranging from 3.5 to 9.1% were obtained for trace metals present with distinctly lower abundance in PM10 (e.g. Ba, Cu, Mn, Sr, Zn). The limits of detection (LOD) calculated as three times the standard deviation (3σ) of the signal derived from filter blank samples ranged from approximately 1?ng?m^?3 (Sr) to 71?ng?m^?3(Ca). The developed procedure was evaluated by comparing the obtained results with the findings derived for the same set of aerosol samples analyzed using a microwave procedure for sample dissolution with subsequent ICP-OES analysis. Finally the developed procedure was applied for the analysis of crustal and trace elements in PM10 samples collected at an urban site (Getreidemarkt, Vienna) and a rural site (Hartberg, Styria), in Austria. The concentrations of the investigated crustal elements varied between some hundred ng?m^?3 and few µg?m^?3 with highest concentrations for Fe and Si, distinctly reduced concentrations ranging from some ng?m^?3 (Sr) to more than hundred ng?m^?3 (K) were found for trace elements. Observed PM10 concentrations were found to be in accordance to literature findings from urban sites in central Europe.     

Flow injection near-infrared determination of ethanol in chloroform

A simple and direct flow injection (FIA) procedure has been developed for the determination of the stabilizing agent ethanol in chloroform samples. The procedure is based on the use of the absorbance band of ethanol in the near-infrared (NIR) region at 2272 nm, measured in front of a reference sample of chloroform stabilized with amylene. The method developed provides a limit of detection of 0.0045% (v/v) and a dynamic range until 10% (v/v) with a typical variation coefficient of 0.4% for six independent analysis of a real sample containing approximately 1% (v/v) of ethanol. The sample injection frequency allowed by the method is 78 h^–1.     

Oil-in-water analysis using supercritical fluid extraction interfaced with fixed wavelength infrared detection

The combination of a direct aqueous supercritical fluid extraction system interfaced to a fixed wavelength infrared detector; measuring CH₂ (ν_asymmetric) absorbance at 2930 cm^?1, has been successfully developed for the analysis of oil-in-water. Using an optional, in-line silica gel treatment procedure, method accuracy for determining Brent Delta crude oil in spiked 500 mL water samples was 92.0% to 94.5% with RSD 4.7% to 6.5%. The supercritical fluid extraction-infrared method enables a second analysis of the same water sample without silica gel treatment. For second sets of analyses without silica gel treatment, method accuracy for determining Brent Delta crude oil in spiked 500 mL water samples was 87% to 96.0% with RSD 7.5% to 9.5%. Results of this study indicate that the silica gel treatment procedure reduces the calculated level of Brent Delta crude oil-in-water by 6.6–12.4% relative to samples analysed without silica gel treatment. The results of a study involving Fourier transform infrared spectroscopy indicate a limit of detection for n-decane of approximately 0.5 mg L^?1 by measuring CH₂ (ν_asymmetric) absorbance using the supercritical fluid extraction-infrared method. Sample preparation using direct aqueous supercritical fluid carbon dioxide extraction provides an indefinite means for the use of infrared techniques to measure oil-in-water.     

Measurements of sulfur in oil using a pressurised wet digestion technique in open vessels and isotope dilution mass spectrometry

Graz University of Technology has developed a new technique for digesting samples using the well-established high-pressure asher (HPA) from Anton Paar GmbH (Graz, Austria). The digestion is performed in semi-open vessels inside a pressurised autoclave. The new HPA equipment consists of a liner for the autoclave, special sample racks and 30-mL digestion vessels made of quartz, covered with PTFE stoppers. The Laboratory for Isotope Dilution and Nuclear Analysis of the Federal Institute for Materials Research and Testing (BAM, Berlin) tested this new equipment in order to assess its usability for the decomposition of larger sample amounts of gas oils for the measurement of sulfur. Several experiments were carried out using the new sample decomposition technique. In order to test the recovery of the new digestion method, a gas oil material with known sulfur content was chosen, quantified by the validated conventional closed vessel HPA digestion in combination with thermal ionisation mass spectrometry. Isotope dilution mass spectrometry has been applied as analytical method in this investigation. The gas oil was spiked with an isotopic spike material, which is enriched in ³⁴S, and was then wet digested in the HPA. The oxidized sulfur of the dried samples was reduced to H₂S and precipitated as As₂S₃. The sulfur was measured as arsenic monosulfide (AsS⁺). The mass content of sulfur in the gas oil tested is 453.5 mg kg^–1. Recovery tests for increasing masses of gas oils indicate that the recovery using the new measurement technique decreases with increasing mass of gas oil. Results were obtained for approximately 0.3 g sample weight and had less overlap with the result of the old HPA method within the stated uncertainties. At approximately 0.5 g sample weight the yield decreases to about 97% and at approximately 1.0 g sample weight to about 87%. In comparison with the conventional closed vessel HPA digestion, the new technique shows no clear advantages for the certification of the sulfur content in gas oil other than a more convenient handling. The total uncertainty of the sulfur mass fractions (k=2) is about 1.5%. Repeated determination of the oil samples show a relative standard deviation of about 0.8% and indicate that the analytical procedure is robust and reproducible. The demonstrated reproducibility allows the establishment of correction factors for the yield, which in turn enables higher sample masses for routine work. The blank level (0.26×10^-6 g) was within the range of the conventional closed HPA digestion procedure·(0.28×10^-6 g). Cross contamination could not be detected. In terms of trace metal analysis a good applicability and more advantages over the conventional closed vessel HPA digestion can be assumed.     

Direct and simultaneous determination of Cr and Fe in crude oil using high-resolution continuum source graphite furnace atomic absorption spectrometry

A simple, fast and sensitive direct method for the simultaneous determination of Cr and Fe in crude oil samples is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry. No sample preparation is used except for a 10-minute homogenization in an ultrasonic bath. Aliquots of 0.1–4 mg of the samples are weighed onto solid sampling platforms and analyzed directly using aqueous standards for calibration. The simultaneous determination was possible because there is a secondary Fe line at 358.120 nm in the vicinity of the most sensitive Cr line at 357.868 nm, and both absorption lines were within the wavelength interval covered by the linear charge-coupled device array detector. It has also been of advantage that the sensitivity ratio between the two analytical lines corresponded roughly to the concentration ratio of the two elements found in crude oil, and that both analytes have very similar volatility, so that no compromises had to be made regarding pyrolysis and atomization temperatures. Two oil reference materials have been analyzed and the results were in agreement with the certified or reported values. Characteristic masses of 3.6 pg and 0.5 ng were obtained for Cr and Fe, respectively. The limits of detection (3σ, n = 10) were 1 µg kg^− 1 for Cr and 0.6 mg kg^− 1 for Fe, and the precision, expressed as the relative standard deviation, ranged from 4 to 20%, which is often acceptable for a rapid direct analytical procedure. Five crude oils samples were analyzed.     

Optimization of a centrifugation and ultrasound-assisted procedure for the determination of trace and major elements in marine invertebrates by ICP OES

A three factor Doehlert design was applied to optimize the extraction of elements in marine invertebrate samples (oyster, mussel and clam) using centrifugation with diluted acids. The factors were: concentration of acid mixture (HCl + HNO₃ + H₃CCOOH; 1–3 mol L^{− 1}), centrifugation time (10–40 min), and rotation velocity (6000–10,000 rpm). In order to evaluate the ultrasound effect on the extraction of trace metals, a portion of the certified oyster tissue sample (NIST 1556b; 0.250 g) was sonicated for 15 min and then the solution was centrifuged at the optimized conditions. The optimized procedure was then applied to nine marine invertebrate samples (oysters, clams and mussels) collected at Todos os Santos Bay, Bahia, Brazil. The optimized condition of the developed method was: 20 min of centrifugation at 9000 rpm using the acid mixture 1.0 mol L^{− 1}. The effect of sonication prior centrifugation was very variable, but it promoted a significant increase in the extraction (12 to 44%) of some trace elements. Moreover, the combination of the centrifugation with sonication offered other advantages, such as improvement of the precision and accuracy, both demonstrated using the oyster tissue reference sample. The results of major and trace elements in marine invertebrate samples showed that elements such us Cd and Cu in oyster samples and Zn in mussel and clam samples were above recommendations, suggesting that its consumption may impose health risks.     

A combined method of sample preparation for the determination of the total element composition of oils

A comprehensive approach to the determination of the elemental composition of oils (including those with a viscosity of 5000 mm²/s) is proposed. It ensures the determination of the most elements present in oils using two versions of sample preparation, autoclave decomposition of oil samples and extraction preconcentration of elements from oil into an aqueous solution on rotating coiled columns (RCCs). The application of RCCs in the elemental analysis of oil ensures the preconcentration of a number of trace elements from oil (including rare-earth elements) and the determination of their concentrations at a level of ng/kg. The preconcentration factor of trace elements from oil using an RCC depends on the volume of oil sample pumped through a constant volume of the stationary phase (acid solution) retained in the column and on the speciation of elements in the oil.     

On-line simultaneous pre-concentration procedure for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry

An on-line pre-concentration system for the sequential determination of cadmium and lead in drinking water by using fast sequential flame atomic absorption spectrometry (FS-FAAS) is proposed in this paper. Two minicolums of polyurethane foam loaded with 2-(6-methyl-2-benzothiazolylazo)-orcinol (Me-BTAO) were used as sorptive pre-concentration media for cadmium and lead. The analytical procedure involves the quantitative uptake of both analyte species by on-column chelation with Me-BTAO during sample loading followed by sequential elution of the analytes with 1.0?mol?L^?1 hydrochloric acid and determination by FS-FAAS. The optimisation of the entire analytical procedure was performed using a Box–Behnken multivariate design utilising the sampling flow rate, sample pH and buffer concentration as experimental variables.

The proposed flow-based method featured detection limits (3σ) of 0.08 and 0.51?µg?L^?1 for cadmium and lead, respectively, precision expressed as relative standard deviation (RSD) of 1.63% and 3.87% (n?=?7) for cadmium at the 2.0?µg?L^?1 and 10.0?µg?L^?1 levels, respectively, and RSD of 6.34% and 3.26% (n?=?7) for lead at the 5.0?µg?L^?1 and 30.0?µg?L^?1 levels, respectively. The enrichment factors achieved were 38.6 and 30.0 for cadmium and lead, respectively, using a sample volume of 10.0?mL. The sampling frequency was 45 samples per hour. The accuracy was confirmed by analysis of a certified reference material, namely, SRM 1643d (Trace elements in natural water). The optimised method was applied to the determination of cadmium and lead in drinking water samples collected in Santo Amaro da Purificação City, Bahia, Brazil.     

Direct determination of nickel in petroleum by solid sampling–graphite furnace atomic absorption spectrometry

A procedure for the direct GFAAS determination of Ni in petroleum samples using a solid sampling strategy is proposed. Palladium was used as conventional modifier. Central composite design multivariate optimization defined the optimum temperature program and the Pd mass, allowing calibration using aqueous analytical solution. The limit of detection (LOD) at the optimized conditions was 0.23 ng of Ni, for typical sample masses between of 0.10 and 0.60 mg. Linearity at least up to 11 ng of Ni and a characteristic mass of 45 pg were observed, defining a dynamic range between 0.52 and 110 μg g⁻¹. Typical coefficients of variation (n = 10) in the analysis of oil reference materials were 7%. Method validation was performed both by the analysis of oil certified reference materials and by comparison with an independent method (ASTM 5863-B). No statistically significant difference was observed between obtained and expected values. The total determination cycle lasted 5 min, equivalent to a sample throughput of 6 h⁻¹ for duplicate determinations.     

The determination of wax esters in lube oil by infrared spectrometry

A simple and rapid method for estimating the content of wax esters in lubricating oils has been developed through the use of isopropanol extraction to concentrate the wax esters. The ratio of the absorption bands at 1740 and 1385 cm^-1 can be used directly for the determination of wax esters in lube oil samples. The method can be satisfactorily applied at levels down to 1 %, with an overall deviation of less than 10 %; for samples containing as low as 0.5 %, the procedure can be used semi-quantitatively with an error of about 20 %. This infrared method can also be used to determine marine and sulfurized wax esters.     

Determination of lecithin and soybean oil in dietary supplements using partial least squares-Fourier transform infrared spectroscopy

Lecithin and soybean oil in dietary supplements were determined by Fourier transform infrared spectrometry transmission measurements in dichloromethane in combination with a partial least squares (PLS) regression. Two different PLS models were developed, using 16 synthetic mixtures of analytes in dichloromethane, making measurements in the spectral range from 931.8 to 1252.3 cm⁻¹ for lecithin and from 911.4 to 1246.9 cm⁻¹ and 1695.3 to 1774.5 cm⁻¹ for soybean oil. Seven products from the Spanish market with lecithin concentrations between 21.1% and 99.1% and soybean oil concentrations between 0% and 37.2% were analyzed by the proposed method and the data was compared to a chromatographic reference procedure obtaining accurate results. For samples spiked with amounts between 50 and 250 mg of lecithin and soybean oil recovery percentages between 98.0% and 102.1% and between 93.6% and 102.0% with an average precision of 0.35% and 0.41% were achieved for lecithin and soybean oil, respectively. This method can be applied for the quality control of dietary supplements.     

Determination of arsenic and antimony in milk by hydride generation atomic fluorescence spectrometry

A highly sensitive procedure has been developed for total arsenic and antimony determination in milk samples by hydride generation atomic fluorescence spectrometry after microwave-assisted sample digestion. The discrete introduction of 2 ml of digested sample in the automated continuous flow hydride generation system allows us to reduce drastically the sample and HCl consume and to determine several elements from a same sample digestion. The method provides detection limits of 0.006 and 0.003 ng ml⁻¹, a sensitivity of 2390 and 2840 fluorescence units per ng ml⁻¹ for As and Sb respectively, and average relative standard deviation of 2.3% for As and 4.8% for Sb. The analysis of cow milk samples, obtained from the Spanish market evidenced the presence of As at concentration levels from 3.4 to 11.6 ng g⁻¹ and Sb levels from 3.5 to 11.9 ng g⁻¹, thus in a proportion near to 1:1, which is in contrast with the 10:1 natural ratio between As and Sb and could evidence the effect of the introduction of new alloys and polymer materials in the industrial process of milk. The method was validated by the comparison of data found for commercial samples by using the proposed procedure and reference methods based on dry-ashing and AFS, and microwave-assisted digestion and inductively coupled plasma mass spectrometry determination.