Continuum Source Graphite Furnace Atomic Research Articles

Application of Disposable Pipette Extraction for Determination of Yb by High‑Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Using Lanthanum as a Chemical Modifier

The use of extraction technique with disposable tips (DPX) was applied for the first time for the extraction and preconcentration of Yb in samples of liquid waste from the petrochemical industry and environmental water using bioabsorbent cork. The use of cork as an extracting phase in the determination of Yb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) was evaluated. The pyrolysis and atomization temperatures were optimized at 1400 and 2400 ºC, respectively. H2SO4, HNO3 and HCl acids were compared in the steps of cleaning the extraction phase and desorption of the analyte by DPX. The best extraction in the selected conditions was obtained with pH 8.0 and 5% v/v HCl. The recoveries were close to 100% for residual water and drinking water, 33 to 77% for produced water and 64 to 93% for river water. Tests with interfering ions in different concentrations were performed. The relative limit of quantification (LOQ) and limit of detection (LOD) were estimated at 0.03 and 0.01 µg L-1, respectively. The total time for the preparation of the samples by DPX was close to 1 min per sample. Extraction and pre-concentration were observed using DPX with a preenrichment factor of approximately 4 times.

Determination of Silver in Environmental Samples by High-resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry after Preconcentration on Bentonite

Determination of Silver in Environmental Samples by High-resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry after Preconcentration on Bentonite

Determination of Cu and Mn in Seawater by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

The conditions for the determination of copper and manganese in seawater by high-resolution continuum-source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) were optimized. The analytical properties were compared with those of low-resolution line source GFAAS (LR-LS GFAAS). The metrological characteristics were estimated considering the dilution of the sample and optimization of the temperature program of the electrothermal atomizer. Using HR-CS GFAAS, the elements were determined in undiluted samples, while LR-LS GFAAS allows the determination only at double dilution. The lower limits of determined Cu concentrations almost coincided for both versions of GFAAS. For manganese, the limits of detection and quantification were significantly lower for HR-CS GFAAS. Calibration curves were plotted using standard solutions. The proposed scheme was tested on water samples from the Sea of Okhotsk by standard addition. The detection limits (LODs) were 0.6 µg L−1 for copper and 0.07 µg L−1 for manganese by HR-CS GFAAS and 0.5 µg L−1 for copper and 0.13 µg L−1 for manganese by LR-LS GFAAS.

Sequential and Simultaneous Determination of Cd, Fe and Ni in Toothpastes Employing Slurry Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

Here is reported an analytical method for the multielemental determination of Cd, Fe and Ni in toothpaste employing slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ET AAS). Using a single sample aliquot, Cd was determined at 228.802 nm, and, sequentially, Fe (232.036 nm) and Ni (232.003 nm) were simultaneously determined. Pyrolysis and atomization temperatures were 800 and 1500 °C for Cd, respectively. An atomization temperature of 2600 °C was used for Fe and Ni. A Pd and Mg mixture was used as the chemical modifier for standards and samples. The procedure for the slurry preparation was optimized using multivariate methodology with a multiple response function while employing a sample mass of about 250 mg. The optimized conditions were: 0.8 mol L−1 HNO3, 0.5% (m/v) Triton X-100 and a sonication time of 15 min. Using aqueous standards for the calibration, limits of detection and quantification were of 3.2 and 10.8 ng g−1 for Cd, 2.2 and 7.4 µg g−1 for Fe, and 0.044 and 0.148 µg g−1 for Ni. The precision estimated as relative standard deviation (n = 5) was 6.1% for Cd, 3.5% for Fe and 4.4% for Ni. The method accuracy was evaluated by standard addition and recovery tests and the recoveries varied from 93 to 114%. The method was applied for the analysis of five toothpaste samples of different brands. The concentrations ranged from 52.0 to 73.6 µg g−1 for Fe, and < 0.148 to 0.227 µg g−1 for Ni. For Cd, the concentrations were below the limit of detection.

Elemental Analysis of Pharmaceutical Products for Chronic Kidney Disease by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR–CS GFAAS)

Here is reported the development of methods for the determination of Al, Cd, Cu, Mo, and Pb by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR–CS GFAAS) after microwave-assisted acid digestion in pharmaceuticals for patients with chronic kidney disease. The measurements were performed at the primary lines of the analytes. The optimum pyrolysis and atomization temperatures were 1800 and 2700 °C for Al, 600 and 1600 °C for Cd, 1400 and 2200 °C for Cu, 1400 and 2600 °C for Mo and 900, and 2400 °C for Pb, respectively. Palladium was used as a chemical modifier for Pb, while Mg(NO3)2 was employed for Al, Cd, and Cu. The validation parameters (linearity, analytical range, accuracy, precision, limit of quantification, and specificity) were obtained according to the stipulations in the Chapter American Pharmacopeia <233>. The limit of detection was 1.63 μg L−1 for Al, 0.02 μg L−1 for Cd, 0.49 μg L−1 for Cu, 0.76 μg L−1 for Mo, and 0.59 μg L−1 for Pb. The precision was between 2.1% for Mo and 8.1% for Al. The recoveries were from 90.2% for Pb to 106.1% for Cd. The developed methods were successfully applied to determine the five analytes in 50 pharmaceutical formulations. Cadmium, Cu, and Mo concentrations were within the maximum limits recommended by the Brazilian Pharmacopeia in all medicines. However, six drug products had a Pb concentration higher than the limit for this element. All samples analyzed showed relatively high concentrations of Al.

Simultaneous determination of Fe and Zn in dried blood spot by HR-CS GF AAS using solid sampling

Dried Blood Spot (DBS) was evaluated as a solid sampling (SS) strategy for the simultaneous determination of Fe and Zn in blood samples by Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (SS HR-CS GF AAS). The alternative lines of Fe and Zn at 307.572 and 307.589 nm, respectively, were evaluated. A good correlation between the area of DBS (in mm2) and volume of blood (in µL) was observed up to 200 µL of blood. A 3.4 mm diameter paper disk, equivalent 3.86 ± 0.13 µL, was punched from the DBS and employed for blood analysis. Random sampling through the area of the paper circle produced by 50 μL blood samples showed no chromatographic effects. The upside of the solid sampling 'boat type' graphite platform was coated with a W-based film. This coating allowed around 350 firings. The use of 3 µL of 15% v/v H2O2 solution as chemical modifier improved both the thermal stability and peak profile of Zn for aqueous medium (standard solution deposited onto Whatman paper), possibly because of the weakening of Zn-paper interactions or even by the formation of thermally more stable Zn oxides. Solid standards used for calibration in the 0.1–3.0 µg Fe and 5.0–50.0 ng Zn ranges were prepared with Whatman 903® paper discs impregnated with standard solutions of the analytes. Results for Fe and Zn determined by the proposed SS HR-CS GF AAS method were in agreement at a 95% confidence level (paired t-test) with those obtained by the comparative method (except for one sample) based on microwave-assisted acid digestion of blood and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS F AAS). The limits of quantification were 10.2 mg/L (0.04 µg) for Fe and 1.2 mg/L (4.6 ng) for Zn. The relative standard deviation was < 10% (n = 12) for a sample containing 516 mg/L Fe and 8.7 mg/L Zn, and the sample throughput was equivalent to ca. 90 s per measurement.

The challenges of Se quantification in bean samples using line and continuum sources atomic absorption spectrometry

This work demonstrates the challenges for selenium (Se) determination in bean samples using high-resolution continuum source Graphite Furnace Atomic Absorption Spectrometry (HR-CS-GF-AAS) and line source Graphite Furnace Atomic Absorption Spectrometry (LS-GF-AAS). Different chemical modifiers were optimized namely; Ir, Ru, and Pd/Mg nitrates. At selenium contents <5 ng g−1, it cannot be quantified accurately. Spectral interferences of the molecular bands of PO and NO as well as the iron lines with Se line at 196.026 were demonstrated. The noticeable low energy of the continuum source of the HR-CS-GF-AAS at 196.026 nm gives high values of the limits of detection and quantification. The Se limits of detection were found to be 24, 33, and 29 ng g−1 for Ir, Ru, and Pd/Mg modifiers, respectively. In situ trapping hydride generation LS-GF-AAS gives better limits of detection and it reached 30 pg g−1 with Ir modifier.

Simultaneous Determination of Chromium and Iron in Powdered Milk Using High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

This work proposes the simultaneous determination of chromium and iron in powdered milk samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) and sample digestion in microwave oven using nitric acid and hydrogen peroxide. The method was established using the primary line (357.869 nm) for chromium and the adjacent secondary line (358.120 nm) for iron while employing aluminum as the chemical modifier. The absorbance signals were measured by peak area using three pixels for both elements. Chromium and iron can be determined in powdered milk samples by the external calibration technique with limits of quantification of 28 ng g−1 for chromium and 19 μg g−1 for iron. The precision was evaluated by using a milk sample with chromium and iron concentrations of 0.76 μg g−1 and 151.3 μg g−1, respectively. The results expressed as relative standard deviation (n = 10) were 2.6% for iron and 3.9% for chromium. The method accuracy was confirmed by the analysis of a milk sample by a comparison of results obtained by the proposed method and those found by employing inductively coupled plasma mass spectrometry (ICP-MS). Five samples were analyzed, and the analyte concentrations found varied from 408 to 805 ng g−1 for chromium. Among the five samples, three had an iron concentration lower than 19 μg g−1 and in the other two samples, the iron concentrations varied from 151 to 199 μg g−1.

Effective and High-Throughput Analytical Methodology for the Determination of Lead and Cadmium in Water Samples by Disposable Pipette Extraction Coupled with High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry (HR-CS GF AAS)

A new procedure for the preconcentration of trace amounts of free Pb and Cd by disposable pipette extraction (DPX) is proposed herein. Recycled cork is used as a biosorbent and the procedure is completely free of organic solvents. The cork was reduced to a powder and characterized by scanning electron microscopy. Several parameters that influence the preconcentration of Pb and Cd with DPX-cork, such as the sample pH, number of extraction cycles, biosorbent mass, and percentage of acid in the desorption step, were studied. The tolerance of DPX-cork with respect to 10 potential interfering ions was also evaluated. Coupled with the high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) technique, the sample preparation method allowed the analytical limits required for quality control (according to the permitted limits established by legislation) to be obtained. The limits of detection for the extraction of a 3.5-mL water sample were 200 ng L−1 for Pb and 100 ng L−1 for Cd. The relative standard deviations were around 7.5% for Pb and 8.0% for Cd. The optimized method was successfully applied to the determination of Cd and Pb in two certified reference materials (water and wastewater) and five water samples (collected from a mangrove, a creek, and the sea).

Determination of Cobalt, Iron, and Nickel in High-Purity Silicon by High- Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Employing Solid Sample Analysis

Analytical Chemistry Department UNESP - Univ. Estadual Paulista, 55 Rua Prof. Francisco Degni

Determination of Antimony in Pharmaceutical Formulations and Beverages Using High-Resolution Continuum-Source Graphite Furnace Atomic Absorption Spectrometry.

A sensitive and accurate method, employing high-resolution continuum source atomic absorption spectrometry, for the determination of antimony (Sb) was developed. Conditions such as pyrolysis and atomization temperatures, the use of chemical modifiers, and sample pretreatment were optimized for the determination of Sb in pharmaceutical preparations and beverages stored in polyethylene terephthalate (PET) containers. In addition to container analysis, the influence of time of contact, temperature, and content composition on the migration of Sb was investigated. Twenty-six samples were periodically analyzed until finalize 1 year bottling. Eight mineral water samples were analyzed after storage at temperatures from 40 to 80°C for 48 h. Five different-colored PET samples were stored at 80°C for 20 days and periodically analyzed. Bottles, containing from 46.4 mg/kg Sb (amber PET) to 91.6 mg/kg Sb (colorless PET), leached Sb depending on the content ingredients, time of contact, and temperature. Although drinking water itself did not promote Sb migration at room temperature, juices and medicines did. After 1 year of storage, the Sb level in the samples ranged from 5 to 50 μg/L. The rate of leaching depended on the temperature, which was slow below 60°C, but rapidly increased at 60-80°C. The higher the Sb content in the bottle, the higher the amount of migration. Because Sb is a possible carcinogen to humans, containers for pharmaceutical use should be better controlled, and factors that increase Sb leaching in products that are widely consumed should be avoided.

Direct and Simultaneous Determination of Copper and Iron in Flours by Solid Sample Analysis and High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

In this work, a simple, fast, and robust method was developed for the direct and simultaneous determination of copper and iron in flours using solid sample analysis and high-resolution continuum source graphite furnace atomic absorption spectrometry. The secondary lines at 217.894 and 217.812 nm were used for all simultaneous measurements of copper and iron, respectively. The pyrolysis and atomization temperatures were of 1400 and 2400 °C, respectively, and no chemical modifier was necessary. The slope of calibration curve obtained, using the rice flour certified reference material (NIST 1568a) as solid standard, presented no significant difference when compared with the slope of external calibration curve using aqueous standard, at 95 % confidence level. Under these conditions, the limits of quantification obtained were 0.38 (Cu) and 0.11 (Fe) mg kg−1, respectively. The relative standard deviations (RSD) varied from 0.5 to 14 % for copper and from 4.9 to 17 % for iron. The method accuracy was confirmed by analysis of two certified reference materials, rice flour NIST 1568a and wheat flour NIST 1567a, and the results were in agreement with the certified values, at 95 % confidence level. The proposed method was applied for the analysis of flour samples (corn, wheat, and white bean), both of conventional and organic cultivation. The concentration values varied in the range of 0.6–5.9 mg kg−1 for copper and of 2.6–50.4 mg kg−1 for iron. The iron concentrations in all samples analyzed were not in agreement with the value established by the Brazilian legislation, which is of 42 mg of iron per kilogram of flour.

Determination of Cd, Ni and V in Spices by Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

This work describes a procedure for determination of Cd, Ni and V in spices by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) using direct solid sampling (SS). The use of Pd/Mg(NO3)2 as modifier for Cd, and an additional air-assisted pyrolysis step allowed the use of aqueous calibration for all analytes. Accuracy was checked by analysis of certified reference materials (CRMs) and the results were in agreement to certified values at 95% confidence level (t-test). Eight samples of spices were analyzed by the proposed procedure and by inductively coupled plasma mass spectrometry (ICP-MS). The found concentrations were 88-233 ng g-1 Cd , 113-2842 ng g-1 Ni and 154-1007 ng g-1 V, with precision generally better than 12%. Results obtained by the proposed procedure were in agreement with those obtained by microwave-assisted digestion and ICP-MS determination. The limits of detection were 0.2, 18 and 7 ng g-1 for Cd, Ni and V, respectively.

Determination of Manganese in Leisure Foods by Incomplete Digestion-Microemulsion Sampling-High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

A fast and effective method was developed for determination of Mn in leisure foods by incomplete digestion-microemulsion sampling-high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). Microemulsions were prepared with digestive liquor and n-butyl alcohol as an auxiliary emulsifier after incomplete digestion treatment. The factors influencing determination were investigated by single factor experimental design. The optimal determination conditions were found as follows: the tartaric acid (1 mg/mL) was added as a chemical modifier with the volume of 4 μL; pyrolysis temperature 1100°C; atomization temperature 2000°C. The results showed that the correlation coefficient was better than 0.996, the characteristic concentration was 0.09 μg/L, the precision (RSD) for 6 replicate measurements of Mn was 2.8% and the average of recoveries was 97.3%. F-test and t-test (95% confidence level) in between the proposed method and the microwave digestion-HR-CS GFAAS method had no significant difference. Therefore, the proposed method was accurate and stable with a high practical value. It provided scientific basis for determination of metal elements in food.

Sequence Determination of Cd and Pb in Honey by Incomplete Digestion-High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

A fast and effective method was developed for sequence determination of Cd and Pb in honey by incomplete digestion-high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS). Cd and Pb in some honey samples using incomplete digestion treatment were measured by HR-CS GFAAS. The factors influencing determination were investigated by single factor experimental design. The optimal determination conditions were found as follows: NH4H2PO4(10mg/mL) were added as a chemical modifier with the volume of 5μL; pyrolysis temperature 600°C(Cd) and 800°C(Pb); atomization temperature 1100°C(Cd) and 1400°C(Pb). Detection limits (3σ,n=12) were found to be 0.06 μg/L and 0.78 μg/L for Cd and Pb, respectively. The precisions (RSD) for 6 replicate measurements of Cd and Pb in honeys were 3.8% and 2.6%, respectively. Recoveries of added Cd and Pb were varied from 95% to 103%. Therefore, the proposed method was rapid, accurate and stable with a high practical value. It provided scientific basis for multi-element sequence determination in food.

Determination of Lead in Eye Shadow and Blush by High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry Employing Direct Solid Sampling

−1 , respectivamente. Direct solid sampling is proposed for Pb determination in eye shadow and blush samples by high- resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). A mixture of Pd(NO3)2 + Mg(NO3)2 was employed as chemical modifier, and aqueous calibration (0.25-2.5 ng Pb, r = 0.998) was obtained. Accuracy of the determination of Pb in eye shadow and blush samples by the proposed method was verified by line source graphite furnace AAS as a comparative technique employing digested samples. The results obtained by the two methods were in agreement at a 95% confidence level (paired t-test). The limit of quantification (dry mass) was 0.020 ng mg −1 . The Pb content in the eye shadow and blush samples varied between 1.222 and 9.632 ng mg −1 and 0.362 and 28.091 ng mg −1 , respectively.

Determination of lead, cadmium, copper, and nickel in the tonghui river of beijing, china, by cloud point extraction-high resolution continuum source graphite furnace atomic absorption spectrometry.

Heavy metal contamination of water has become an important problem in recent years. Most hazardous heavy metals exist in environmental water in trace or ultra-trace amounts, which requires establishing highly sensitive analytical methods. In this research, quantitative analyses were performed using high-resolution continuum source graphite furnace atomic absorption spectrometry combined with cloud point extraction (CPE) to determine Pb, Cd, Cu, and Ni levels in environmental surface water. By optimizing the CPE conditions, the enrichment factors were 29 for Pb, Cd, and Cu and 25 for Ni. The limits of detection (LOD) were 0.080, 0.010, 0.035, and 0.014 μg L for Pb, Cd, Cu, and Ni, respectively. The sensitivity of the method is comparable with those reported in previous investigations using various methods and improves outcome by 2 to 3 orders of magnitude compared with the LODs of the current national standard methods of China. Our method was used to determine Pb, Cd, Cu, and Ni in 55 water samples collected from the Tonghui River, which is the principal river in the urban area of Beijing, China. The results indicated that the distributions of the four heavy metals in the Tonghui River were related with the environments. The levels of Pb and Ni exhibit increasing trends along the river from upstream to downstream possibly due to the existence of some chemical factories in the downstream area. Lead, Cd, Cu, and Ni averaged 13.9, 0.8, 46.8, and 38.5%, respectively, of the total amount of the determined heavy metals. The levels of the four heavy metals conformed to the Environmental Quality Standards for Surface Water (Grade I) of China. This work provides a reliable quantitative method to determine trace-amount heavy metals in water, which lays a foundation for establishing standards and regulations for environmental water protection.

Determination of Lead in Lipstick by Direct Solid Sampling High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry: Comparison of Two Digestion Methods

A new analytical procedure for the determination of lead in lipstick has been developed using direct solid sampling high resolution continuum source graphite furnace atomic absorption spectrometry (SS HR CS GFAAS). The performance of this method has been compared to acid digestion methods for sample preparation, with or without hydrofluoric acid (HF) with inductively coupled plasma mass spectrometry (ICP-MS) detection. Good reliability was obtained for all three methods; the results obtained for certified reference materials with concentrations between 1 and 20 ppm were in agreement with the certified values. However, for materials with complex matrices, such as pearl or Ca-Na borosilicate, only ICP-MS with HF sample digestion or AAS with direct solid sampling allowed complete recovery of lead. To avoid the use of hazardous acids, the development of SS HR CS GFAAS is an interesting alternative. With the AAS method, a characteristic mass of 13.2 pg of lead was obtained, and the limit of detection was 0.005 µg/g. The performance of the method was evaluated by determining lead in lipstick. The use of the solid sampling technique constitutes a good alternative for accurate and rapid determination of lead content in lipstick and cosmetic raw materials, with a suitable limit of detection and a reduced risk of contamination or of analyte loss. Another alternative would be to use ICP-MS determination in conjunction with microwave-assisted acid digestion without the use of HF, which implies accepting a quantification of “nearly total” lead, closer to a “bio-extractible” fraction.

Determination of Lead in Human Hair by High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry with Microwave Digestion and Solid Sampling

The content of lead in human hair was measured by high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) combined with microwave-assisted digestion (MAD) and direct solid sampling (DSS). Hair strands were washed, dried, and then cut into three parts (root, middle portion, and tip). For MAD-GFAAS assays, approximately 0.25 g of hair was completely digested using a mixture of concentrated nitric acid and hydrogen peroxide in a closed system. In the DSS-GFAAS assays, 0.1–0.2 mg of dried hair was directly introduced into a graphite furnace using a solid autosampler. The temperature programs were optimized and the effects of various added modifiers were compared. The results indicated that NH4H2PO4 was the optimal modifier for analysis of Pb using GFAAS. Use of the optimal modifier and temperature program gave similar limits of detection for MAD-GFAAS and DSS-GFAAS of 1.16 ng/g and 0.82 ng/g, respectively. Both methods also produced satisfactory recoveries ranging from 98.69% to 103.14%. There was no significant difference observed between the Pb contents of hair strands determined by the MAD-GFAAS and DSS-GFAAS assays, which both indicated that the Pb levels increased along the hair strands. Comparison of the two methods revealed that DSS-GFAAS had several advantageous characteristics over MAD-GFAAS, including the need for much less sample material and having a less time-consuming procedure, lower sample blank absorbance, lower memory effect, and no risk of environmental pollution by digesting chemicals. The direct solid sampling technique can be employed as a good alternative to conventional wet digestion in AAS assays.

Evaluation of Brazilian and Venezuelan Crude Oil Samples by Means of the Simultaneous Determination of Ni and V as Their Total and Non-volatile Fractions Using High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

The simultaneous determination of Ni and V as their total and non-volatile fractions in crude oil samples using high-resolution continuum source graphite furnace atomic absorption spectrometry is proposed. The simultaneous determination was possible because a secondary Ni line at 305.432 nm and a secondary V line at 305.633 nm are within the wavelength interval covered by the linear charge-coupled device array detector. Moreover, both analytes have similar volatility, enabling the use of the same pyrolysis and atomization temperatures. Oil-in-water emulsions were used for crude oil sample preparation. Nitric acid was added to the emulsion only for the determination of total Ni and V concentrations. In the absence of the acid, the volatile fractions have been lost in the pyrolysis stage and only the thermally stable fractions were determined. The concentration of the volatile fractions could be obtained by difference. The results for the total concentrations were in agreement with the certified values or those reported in the literature, with minor exceptions, for previously analyzed samples, according to a 95% statistical confidence interval. The limits of detection (3s; n = 10) were 3 μg g−1 for Ni and 1 μg g−1 for V. The precision, expressed as the relative standard deviation, was better than 9%. The characteristic mass values were 320 and 85 pg for Ni and V, respectively.