Determination of refractory elements in used lubricating oil by ICPOES employing emulsified sample introduction and calibration with inorganic standards.
Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro, 22453-900, Brazil.
The quantification of trace elements in used lubricating oil is useful for evaluating the wearing of specific components of engines. In the present work, inductively coupled plasma optical emission spectrometry (ICPOES) was used for determining five refractory elements (Ni, Mo, Cr, V and Ti) in lubricating-oil samples. The methodology was developed while aiming at the introduction of such organic samples into the ICP as emulsions. Several nebulization systems were tested with clear advantage for Meinhard K3 coupled with a cyclonic spray chamber. The carbon deposition on the injector tip as well as the plasma background was minimized through careful optimization of the Ar and O2 gas mixture flows into the plasma. The optimization of instrumental and experimental parameters allowed quantification using calibration curves prepared with analyte inorganic standards. An internal standard (Sc) was used to correct the matrix effects and signal fluctuations. The limits of detection (3Sb/m), in the ng g(-1) range were obtained for all five elements. The methodology was validated through an analysis of standard reference materials (SRM 1084a, 1085a and 1085b). Good analyte recoveries (from 92.6 to 104.7%) were achieved. Comparison studies against established ICPOES methodologies (sample acid decomposition or sample direct dilution in an organic solvent) have shown that the proposed methodology present clear advantages in terms of simplicity of sample preparation, overall analysis time, and the use of inorganic standards for calibration instead of expensive metallorganic standards.
Determination of Hg and Pb in fuels by inductively coupled plasma mass spectrometry using flow injection chemical vapor generation.
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan.
An isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Hg and Pb in fuels using flow injection vapor generation (VG) as the sample introduction system. A simple and inexpensive in-situ nebulizer/vapor generator was employed in this study. An emulsion containing 10% v/v fuel, 2% m/v Triton X-100 and 1.0% m/v tartaric acid was injected into VG-ICP-MS system for the determination of Hg and Pb. Sodium borohydride was used for vapor generation. Since the sensitivities of Hg and Pb in emulsion and those in aqueous solution are quite different, isotope dilution and standard addition methods were used for the determination of Hg and Pb in selected fuel samples. The influences of vapor generation conditions and emulsion preparation on the ion signals are reported. This method has been applied for the determination of Hg and Pb in various fuel samples such as diesel, gasoline and engine oil obtained locally. The analytical results obtained by isotope dilution and standard addition methods were in good agreement with each other and also with those of digested samples analyzed by pneumatic nebulization ICP-MS. Under the optimum operating conditions, the detection limits obtained were 0.02 and 0.03 ng mL(-1) for Hg and Pb, respectively, in prepared emulsified solutions, corresponding to 0.2 and 0.3 ng mL(-1) of Hg and Pb, respectively, in the original fuel samples.
Anal Sci. 2009 Jan ;25 (1):95-100 19139580
Evaluation of lubricating oil preparation procedures for the determination of Al, Ba, Mo, Si and V by high-resolution continuum source FAAS.
São Paulo State University-UNESP, Department of Analytical Chemistry, Araraquara-SP, Brazil.
Microwave-assisted acid decomposition and oil-in-water emulsification were evaluated as sample pretreatment procedures to determine Al, Ba, Mo, Si and V in lubricating oils by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Average recoveries of Al, Ba and V in oil digests (107, 103 and 101%) were close to those obtained for emulsions prepared in kerosene medium (94, 113 and 95%). Average recoveries for Mo were close to 105 and 46% for emulsions and digests, respectively. Improved average recoveries (101%) were obtained for Mo in digests using the analyte addition technique. Silicon was successfully quantified only in digested samples. Limits of quantification for Al, Ba, Mo and V were 1.4, 31.5, 1.5 and 11.4-fold lower than those obtained by line-source FAAS. Enhanced sensitivity, multi-elemental capability, and high sample throughput are among the main advantages of HR-CS FAAS in comparison with the line-source FAAS technique.
Determination of vanadium in petroleum and petroleum products using atomic spectrometric techniques.
Fábio A C Amorim, Bernhard Welz, Antônio C S Costa, Fábio G Lepri, Maria Goreti R Vale, Sérgio L C Ferreira
Universidade Federal da Bahia, Instituto de Química, Grupo de Pesquisa em Química Analítica, Campus Universitário de Ondina, Salvador, BA 40170-290, Brazil; Universidade Federal da Bahia, Instituto de Ciências Ambientais e Desenvolvimento Sustentável, Av. José Seabra s/n, Barreiras, BA 40805-100, Brazil.
Vanadium is recognized worldwide as the most abundant metallic constituent in petroleum. It is causing undesired side effects in the refining process, and corrosion in oil-fired power plants. Consequently, it is the most widely determined metal in petroleum and its derivatives. This paper offers a critical review of analytical methods based on atomic spectrometric techniques, particularly flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ET AAS), inductively coupled plasma optical emission spectrometry (ICP OES), inductively coupled plasma mass spectrometry (ICP-MS). In addition an overview is provided of the sample pretreatment and preparation procedures for vanadium determination in petroleum and petroleum products. Also included are the most recent studies about speciation and fractionation analysis using atomic spectrometric techniques.
Determination of arsenic in diesel, gasoline and naphtha by graphite furnace atomic absorption spectrometry using microemulsion medium for sample stabilization.
Department of Chemistry, Pontifical Catholic University, Rua Marques de S. Vicente, 225, Gávea, 22453-900, Rio de Janeiro, RJ, Brazil, email@example.com.
A procedure for the determination of As in diesel, gasoline and naphtha at mug L(-1) levels by GFAAS is proposed. Sample stabilization was achieved by the formation of three component solutions prepared by mixing appropriate volumes of the samples propan-1-ol and nitric acid aqueous solution. This mixture resulted in a one-phase medium, which was indefinitely stable. No changes in the analyte signals were observed over several days in spiked samples, proving long-term stabilization ability. The use of conventional (Pd) and permanent (Ir) modification was investigated and the former was preferred. Central composite design multivariate optimization defined the optimum microemulsion composition as well as the temperature program. In this way, calibration using aqueous analytical solutions was possible, since the same sensitivity was observed in the investigated microemulsion media and in 0.2% v/v HNO(3). Coefficients of correlation larger than 0.999 and an As characteristic mass of 22 pg were observed. Recoveries (n=4) obtained from spiked samples were 98+/-4, 99+/-3 and 103+/-5%, and the limits of detection in the original samples were 1.8, 1.2 and 1.5 mug L(-1) for diesel, gasoline and naphtha, respectively. Validation was performed by the analysis of a set of commercial samples by independent comparative procedures. No significant difference (Student's t-test, p<0.05) was observed between comparative and proposed procedure results. The total determination cycle lasted 4 min for diesel and 3 min for gasoline and naphtha, equivalent to a sample throughput of 7 h(-1) for diesel and 10 h(-1) for gasoline and naphtha.
Anal Sci. 2005 Nov ;21 (11):1365-9 16317907
University of Oulu, Department of Chemistry, Finland. firstname.lastname@example.org
Certain wear metals (Fe, Cr, Ni, Cu and Zn) of various lubrication oils were determined by means of ICP-OES and FAAS. The kerosene dilution method, which is used widely together with ICP-OES, was applied with both methods here. Calibration standards were made from a commercial organo-metallic standard. Our aim was to clarify the possibility of using the quick kerosene dilution method together with FAAS for a rapid check for certain indicator metals. Metal determinations with FAAS were accurate enough for quantitative work in machine condition diagnostics and waste oil characterization, when compared with those with ICP-OES.
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Direct μ-flow injection isotope dilution ICP-MS for the determination of heavy metals in oil samples.
Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain. email@example.com
The determination of trace elements in oil samples and their products is of high interest as their presence significantly affects refinery processes and the environment by possible impact of their combustion products. In this context, inductively coupled plasma mass spectrometry (ICP-MS) plays an important role due to its outstanding analytical properties in the quantification of trace elements. In this work, we present the accurate and precise determination of selected heavy metals in oil samples by making use of the combination of μ-flow direct injection and isotope dilution ICP-MS (ICP-IDMS). Spike solutions of (62)Ni,(97)Mo,(117)Sn and (206)Pb were prepared in an organic solvent, mixed directly with the diluted oil samples and tested to be fit for purpose for the intended ID approach. The analysis of real samples revealed strong matrix effects affecting the ICP-MS sensitivity, but not the isotope ratio measurements, so that accurate results are obtained by ICP-IDMS. Typical relative standard deviations were about 15% for peak area and peak height measurements, whereas the isotope ratios were not significantly affected (RSD < 2%). The developed method was validated by the analysis of a metallo-organic multi-element standard (SCP-21, typically applied as a calibration standard) and the standard reference material SRM1084a (wear metals in lubricating oil). The obtained results were in excellent agreement with the certified values (recoveries between 98% and 102%), so the proposed methodology of combining μ-flow direct injection and ICP-IDMS can be regarded as a new tool for the matrix-independent, multi-element and reliable determination of trace elements in oil and related organic liquids.
Talanta. 2011 Apr 15;84 (2):335-40 21376954
Determination of inorganic contaminants in glue by inductively coupled argon plasma optical emission spectrometry.
Institute of Chemistry, University of Campinas, P.O. Box 6154, 13083-970 Campinas, SP, Brazil.
A closed vessel method using a microwave oven was developed for the determination of As, B, Ba, Bi, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, Sn and Sb by Inductively Coupled Argon Plasma Optical Emission Spectrometry (ICP OES). The method was applied to samples of polyvinyl acetate-based glue in water emulsions. Parameters such as wavelength, nebulization pressure and RF power were optimized and the residual acidity after the digestion process was determined. The addition of internal standards was evaluated and the accuracy of the proposed method was verified with addition and recovery experiments and also with certified reference materials, achieving good results. Using a nebulization flow rate of 0.73 L min(-1)and a RF power of 1200 W it was possible to obtain adequate values for limit of detection and limit of quantification as well as recovery values in the range of 80-106%, for all the analytes. The analysis of coloured glue samples (white, black, blue, yellow, red and green), widely used by children, showed no contamination by the elements studied.
[Determination of 27 inorganic elements in Limonium bicolor by ICP-MS using microwave digestion for sample preparation].
School of Food and Pharmacy, Zhejiang Ocean University, Zhoushan 316000, China. firstname.lastname@example.org
An inductively coupled plasma mass spectrometry (ICP-MS) for determination of the contents of 27 inorganic elements in Limonium bicolor after microwave digestion of the sample was developed. The accuracy of the method was evaluated by the analysis of corresponding inorganic elements in standard reference materials (GBW 07605), and matrix effect and signal drift were compensated by using the internal standard elements (Ge, In and Bi). By applying the proposed method, the contents of 27 inorganic elements in Limonium bicolor collected from Dongying (Shandong Province of China) were determined. The precision of measurement ranges from 1.5% to 9.7% in terms of relative standard deviation. The recoveries and the limits of detection are in the range of 92.4%-107.2% and 0.002-0.081 microg x L(-1), respectively. It is indicated that the proposed method has the advantages of simplicity, speediness and sensitivity. The results showed that the Limonium bicolor are rich in major elements Na, K, Ca and Mg and trace elements Fe, Mn, Zn, Cr and Cu. This paper provides scientific basis for deeply studying the relation between the inorganic elements and the drug effects of Limonium bicolor.
Ultrasound-assisted emulsification of cosmetic samples prior to elemental analysis by different atomic spectrometric techniques.
Departamento de Química Analítica y Alimentaria, Area de Química Analítica, Facultad de Química, Universidad de Vigo, As Lagoas-Marcosende s/n, 36310 Vigo, Spain.
In this work, ultrasound-assisted emulsification with a probe system is proposed as a rapid and simple sample treatment for atomic spectrometric determinations (Electrothermal Atomic Absorption Spectrometry, Inductively Coupled Plasma Optical Emission Spectrometry, Flame Atomic Absorption Spectrometry and Cold Vapour Atomic Absorption Spectrometry) of trace elements (As, Cd, Cr, Cu, Hg, Mg, Mn, Ni, Sr and Zn) in cosmetic samples such as shampoos, gel (hair gel), crèmes (body milk, hair conditioner) and oil (body oil). The type of dispersion medium, the sample mass-to-dispersion medium volume ratio, as well as the parameters related to the ultrasound-assisted emulsification (sonication amplitude and treatment time) were exhaustively studied. Only 1 min of ultrasonic shaking and a dispersion medium containing 0.5%(w/v) of SDS+3%(v/v) of HNO(3) or HCl allows obtaining a stable emulsion at least for 3 months. Thermal programs, nebulization of emulsions, speed of pumps and concentration of reagents used in cold vapour generation were optimized. Calibration using aqueous standards was feasible in all cases. Calibration by the standard addition method and recovery studies was also applied for validation. Microwave-assisted digestion and Inductively Coupled Plasma Mass Spectrometry were used for comparison purposes. Relative standard deviations from analysis of five independent emulsions were less than 9% in all cases.
Determination of trace elements in residual oil by high-resolution inductively coupled plasma mass spectrometry.
School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China. email@example.com
An analytical method using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 20 elements, including Na, Mg, Al, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, and Pb elements, in residual oil was described. The sample was dissolved in HNO(3) by microwave digestion, and then the above 20 elements in the solution were analyzed directly by HR-ICP-MS. Most of the spectral interferences could be avoided by measuring in the high-resolution mode. The matrix effect caused by the sample-digesting solution and corrected by Sc, Rh, and Bi as the internal standard elements was studied in detail. The optimum condition of the determination was also tested and discussed. The result showed that the detection limits of the method were in the range of 0.014 to 11.6 microg L(-1); the relative standard deviation was less than 3.8% and recoveries in the samples were in the range of 88.4% to 108.0%. This method can be used to determine the trace elements in residual oil with the features of accurate, rapid, and convenient determination.
Ind Health. 2008 Dec ;46 (6):582-93 19088410
National Institute of Occupational Safety and Health, Kawasaki, Japan.
A simple direct injection method for analysis of polycyclic aromatic hydrocarbons (PAHs) or other organic components of particulate matter by gas chromatography/mass spectrometry (GC/MS) was developed. This method uses a small custom brass capsule to insert a particulate sample deposited on a quartz fiber filter or powdery sample directly into a GC injector inlet. This approach was applied in the analysis of PAHs in diesel emissions and other particulate samples, which are introduced into the GC and analyzed by MS using selected ion monitoring mode. Quantitation is based on the concentration of PAHs in a standard reference material (SRM), which are certified by US National Institute of Standard Technology to avoid matrix effects on extraction efficiency. A standard filter is prepared by deposition of small amount of SRM of diesel particulate or ambient PM on quartz fiber filter. By this method, the linearity for 12 kinds of PAHs (3 to 6 rings) was demonstrated from 0.022 mg to 0.65 mg of SRM 1650. The linearity of BaP, for example, was confirmed from 0.028 to 0.845 ng. The reproducibility of this method determined by analyzing the standard filter was 15.4%. By selecting an appropriate SRM as a standard material, this method is applicable for analyzing PAHs in fine particulate matter of less than 1 microm from various origins. Preliminary results for a series of ambient particulate matter, roadside PM, diesel soot and sidestream smoke, are presented. This method enables analysis of organic chemical substances, for example PAHs, in PM without any pretreatment using organic solvent, and without any expensive modification of GC instrument.
Single-step microwave digestion with HNO(3) alone for determination of trace elements in coal by ICP spectrometry.
Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8569, Japan.
A microwave digestion method with HNO(3) alone was conducted at a temperature as high as 250 degrees C for determination of 19 trace elements (Li, Be, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Cd, Cs, Ba, Hg, and Pb) in coal jointly by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and flow injection ICP-MS (FI-ICP-MS). The validity of determination was assessed by using three standard coals, SRM 1632c, BCR 180, and SARM 19. It was found that the high-temperature digestion led to an extensive decomposition of the organic matrix and clay in coal, and no dissolved and solid carbon remained in the final solution after evaporation. Good recoveries were observed for all trace elements in three coals, with the exception of V, Rb, and Cs in high-ash SARM 19. Additionally, FI-ICP-MS combined with the present digestion without evaporation pretreatment was proved to be a rapid and efficient approach for determination of ultra-trace elements such as Se, Cd, and Hg in coal.
Direct and simultaneous determination of arsenic, manganese, cobalt and nickel in urine with a multielement graphite furnace atomic absorption spectrometer.
Department of Chemistry, National Tsing Hua University, Hsinchu 300, Taiwan.
A simple method was developed for the direct and simultaneous determination of arsenic (As), manganese (Mn), cobalt (Co), and nickel (Ni) in urine by a multi-element graphite furnace atomic absorption spectrometer (Perkin-Elmer SIMAA 6000) equipped with the transversely heated graphite atomizer and longitudinal Zeeman-effect background correction. Pd was used as the chemical modifier along with either the internal furnace gas or a internal furnace gas containing hydrogen and a double stage pyrolysis process. A standard reference material (SRM) of Seronormtrade mark Trace Elements in urine was used to confirm the accuracy of the method. The optimum conditions for the analysis of urine samples are pyrolysis at 1350 degrees C (using 5% H(2) v/v in Ar as the inter furnace gas during the first pyrolysis stage and pure Ar during the second pyrolysis stage) and atomization at 2100 degrees C. The use of Ar and matrix-free standards resulted in concentrations for all the analytes within 85%(As) to 110%(Ni) of the certified values. The recovery for As was improved when mixture of 5% H(2) and 95% Ar (v/v) internal furnace gas was applied during the first step of a two-stage pyrolysis at 1350 degrees C, and the found values of the analytes were within 91-110% of the certified value. The recoveries for real urine samples were in the range 88-95% for these four elements. The detection limits were 0.78mugl(-1) for As, 0.054mugl(-1) for Mn, 0.22mugl(-1) for Co, and 0.35mugl(-1) for Ni. The upper limits of the linear calibration curve are 60mugl(-1)(As); 12mugl(-1)(Mn); 12mugl(-1)(Co) and 25mugl(-1)(Ni), respectively. The relative standard deviations (R.S.D.s) for the analysis of SRM were 2% or less. The R.S.D.s of a real urine sample are 1.6%(As), 6.3%(Mn), 7.0%(Ni) and 8.0%(Co), respectively.
Flow injection on-line dilution for multi-element determination in human urine with detection by inductively coupled plasma mass spectrometry.
Department of Chemistry, Technical University of Denmark, Building 207, 2800 Lyngby, Denmark.
A simple flow injection on-line dilution procedure with detection by inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of copper, zinc, arsenic, lead, selenium, nickel and molybdenum in human urine. Matrix effects were minimized by employing a dilution factor of 16.5 with on-line standard addition, and (103)Rh was used as internal standard to compensate for signal fluctuation. The procedure was validated by the analysis of two standard reference materials SRM 2670 (NIST) and Seronormtrade mark Trace Elements in Urine. Recovery experiments were performed by spiking the reference materials as well as artificial urine. The detection limits (mug l(-1)) were 0.12,0.96,0.30,0.09,0.45,0.08,0.09, and the precisions (RSD,%) were 2.6,2.3,3.0,3.7,3.7,4.9,2.8 for Cu, Zn, As, Pb, Se, Ni and Mo, respectively. The procedure was applied to the analysis of 41 human urine samples. No correlations between the concentrations of the elements were observed.
Open Laboratory of Ore Deposit, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China.
Proposed is a simple and reliable method for the dissolution of granite and the determination of 38 elements by inductively coupled plasma mass spectrometry. One hundred milligrams of sample are digested with 1 ml of HF and 0.5 ml of HNO(3) in screw top PTFE-lined stainless steel bombs at 190 degrees C for 12 h. Insoluble residues are dissolved using 8 ml of 40% HNO(3)(v/v) heated to 110 degrees C for 3 h. Six granite standard reference materials (GSR-1, JG-2, G-2, NIM-G, SG-3, SG-1a) were studied. Analytical calibration was accomplished using aqueous standard solutions. Rhodium was used as an internal standard to correct for matrix effects and instrument drift. We report data for: Li, Be, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cs, Ba, Hf, Ta, W, Pb, Th, U and 14 of the rare earth elements. The recoveries for most of these elements in granite ranged from 90 to 110%.