Method For Determination Of Cd Research Articles

A greener, rapid and accurate microwave-assisted hydrogen peroxide digestion method for ICP-OES determination of heavy metals in pet food samples

Microwave-assisted hydrogen peroxide digestion (MW-AHPD) method for determination of Cd, As, Pb, Sn, and Cr in South African pet food samples by inductively coupled plasma-optical emission spectroscopic (ICP-OES) is reported. Multivariate tools and wheat flour certified reference material (FAP80467) assessed limiting factors and reproducibility of the methods respectively. The resulted optimum conditions were: 200 °C, 40 mins, 0.5 g, and 5 mol/L for temperature, time, sample mass and H2O2 concentration, respectively. The method demonstrated excellent accuracy (96–98%), reproducibility (≤ 2.1%) and high detection limits (0.0675–0.3765 µg/g). Then, real pet food samples made from maize, rice, vegetables, fish, and wheat were digested and concentration levels of Cd, Pb, As, Cr and Sn ranged between 11.2 and 22.6, 6.4–11.9, 3.44–13.4, 0.44–2.98 and 0.18–0.98 µg/g, respectively. The three metal ions were above the minimum tolerable limits (Cd: 10 µg/g, Pb:10 µg/g, As: 12.5 µg/g) for some of the fish and wheat based pet food according to the South African regulatory standard. Furthermore, using the AGREEPrep metric tool the method was assessed and had a score of 0.76, confirming its greenness. These findings present MW-AHPD method as an alternative for determination of heavy metals in pet food by ICP-OES.

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.

Dispersive liquid-liquid microextraction based on deep eutectic solvent for elemental impurities determination in oral and parenteral drugs by inductively coupled plasma optical emission spectrometry

A simple, fast, sensitive and green pretreatment method for determination of Cd, Co, Hg, Ni, Pb and V in oral and parenteral drug samples using inductively coupled plasma optical emission spectrometry (ICP OES) has been developed. According to United States Pharmacopoeia (USP), those metals must be reported in all pharmaceutical products for quality control evaluation (i.e., elemental impurities from classes 1 and 2A of USP Chapter 232). To improve the analytical capabilities of ICP OES, a dispersive liquid-liquid microextraction (DLLME) has performed using a safe, cheap and biodegradable deep eutectic solvent (DES) as extractant solvent (a mixture of 2:1 M ratio of DL-menthol and decanoic acid). Seven parameters affecting the microextraction efficiency have carefully optimized by multivariate analysis. Under optimized conditions, the DES-based DLLME-ICP OES procedure improved limit of quantitation (LOQ) values on range from 12 to 85-fold and afforded an enrichment factor on average 60-times higher than those obtained to direct ICP OES analysis. Consequently, LOQ values for Cd, Co, Hg, Ni, Pb and V have been on average 10-times lower than target limits recommended for drugs from parenteral route of administration. Trueness has evaluated by addition and recovery experiments following USP recommendations for three oral drug samples in liquid dosage form and three parenteral drugs. Recovery and RSD values have been within the range of 90–109% and 1–6%, respectively. All analytes were below the respectives LOQ values, hence, lower than the limits proposed by USP Chapter 232.

Development and Collaborative Study of a Diluted Acid Mild Extraction Method for Determination of Cadmium in Grain by Graphite Furnace Atomic Absorption Spectrometry.

The traditional pretreatment methods for the determination of cadmium in grain are time-consuming, cost-consuming, and unfriendly to human health and the environment. To eliminate these disadvantages, we developed an accurate, time-, energy- and cost-efficient method for determination of Cd in grain coupled with graphite furnace atomic absorption spectrometry (GFAAS). The optimization conditions of the extraction were achieved, the accuracy was verified and a collaborative study was organized to evaluate the methods. The detection limit and quantification limit were 0.016 and 0.048 μg L-1, respectively. The whole pretreatment time was reduced to 15 min, and there was no significant difference (P >0.05) between the extraction method and the classic pretreatment method. The method proved to be highly consistent with the results of laboratories in different countries, as determined from two international proficiency tests (| Z | ≤0.3). The repeatability, reproducibility, and HorRat values of the collaborative results were 2.7 - 4.9%, 9.4 - 11.7%, and 0.42 - 0.58, respectively. The method of diluted acid mild extraction coupled with GFAAS is efficient, cost-saving, convenient and friendly.

Application of cysteamine functionalized CdS hollow nanospheres in determination of Cd(II) and Pb(II) in the presence of each other by resonance light scattering technique

This work reports on the development of a method for determination of Cd(II) and Pb(II) in the presence of each other using resonance light scattering (RLS) technique. In this regard, cysteamine functionalized CdS hollow nanospheres were synthesized and used as a probe. The synthesized hollow nanospheres were fully characterized using SEM, TEM, XRD, DLS and FTIR measurements. By the aid of synchronous scanning of the excitation and emission monochromators of a conventional spectrofluorometer, RLS spectra of the synthesized nanospheres in the presence and absence of the investigated metal ions were studied, and enhancement effect of the investigated metal ions was observed. The results showed that under different optimized conditions, it is possible to determine the investigated metal ions in the presence of each other with detection limits of 9.0 and 10.0μgL−1 for Pb(II) and Cd(II), respectively. Furthermore, the real sample analysis results confirmed the method applicability for accurate analysis of real water samples.

Determination of Cd and Cr in tannin samples by high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample sequential analysis (HR-CS SS-GF AAS)

A fast and reliable analytical method for the sequential determination of Cd and Cr in tannin samples by HR-CS SS-GF AAS from the same sample aliquot is proposed.

DETERMINATION OF Cd AND Pb IN XANTHAN GUM SAMPLES BY GF AAS

This paper describes the evaluation of a method for determination of Cd and Pb in xanthan gum samples by Graphite Furnace Atomic Absorption Spectrometry (GF AAS) using NH4H2PO4 as the chemical modifier. The sample preparation was performed using a reflux system adapted in the digestion tubes. With this system it was possible to increase the temperature of the digester block above the boiling point of the reaction medium, preventing loss of analyte and excessive evaporation of acids during heating. Samples were digested with HNO3 for 3 h in a digester block at 220 oC. The limits of detection for Cd and Pb were 2.2 and 33.8 ng g-1, respectively. The RSDs for both analytes were, on average, lower than 5.0% and accuracy was verified by recovery tests, yielding values in the 83-100% range.

Sample preparation methods for determination of Cd, Pb and Sn in meat samples by GFAAS: use of acid digestion associated with a cold finger apparatus versus solubilization methods

The aim of this study was to present three sample preparation methods for the determination of Cd, Pb and Sn in meat by Graphite Furnace Atomic Absorption Spectrometry (GFAAS): acid digestion, solubilization with tetramethylammonium hydroxide and formic acid. For the digestion with HNO3, a conventional open system with a cold finger was used. This system helped to avoid losses of analytes and reagents by volatilization, permitting to operate at high temperatures applied at a digester block and reducing the digestion time (∼1 h). Solubilizations were performed at room temperature. The slurry was left standing overnight and remained closed until achieving complete solubilization. The temperature program of the graphite furnace was optimized for each element in the different means of preparation samples using a mixture of Pd–Mg. The figures of merit were similar for all sample preparation methods evaluated. The limits of detection obtained for the acid digestion procedure were 0.0006, 0.0164 and 0.0520 μg g−1 for Cd, Pb and Sn, respectively. In order to evaluate the accuracy of the results obtained by the three sample preparation methods, recovery tests for four real meat samples were performed and the recoveries ranged from 93.7 to 109%, supporting the accuracy of the method. Also, different certified reference materials of meat were analyzed and the results obtained were in agreement with the certified value at 95% of confidence (t-test). The best results were obtained by the acid digestion procedure with the cold finger system. This procedure is faster, the system is semi-closed with no significant contamination or loss of analytes by volatilization and it provides a better signal/noise ratio.

Application of the high-speed self-reversal background corrector to the determination of cadmium by chemical vapor generation atomic absorption spectrometry

Concentrations of cadmium (Cd) in extracting solutions (neutral salts) from contaminated soils are often too low to be determined by conventional flame atomic absorption spectrometry. For this reason, determination of Cd requires sensitive analytical methods free from interference problems generated by samples. In this context, vapor generation atomic absorption spectrometry (HGAAS) was combined with a high-speed self-reversal background corrector. This new approach was successfully applied after optimization of the analytical parameters to obtain a maximal absorbance signal of the volatile Cd species. The optimum condition was achieved with a 3% (m/v) NaBH4 in 1.5% (m/v) NaOH reducing solution and a solution containing 0.3 mol/L HNO3. The detection limit was 1 ng mL–1 under the previous conditions and the relative standard deviation was up to 5% for 10 replicate analyses of Cd at 0.2 and 1 ng mL–1, reflecting a very highly sensitive and reproducible method. Moreover, the results showed that the proposed combination was an efficient method to overcome the interference problems caused by different coexisting cations, As, Al, Ca, Cu, Fe, Mg, Mn, Ni, Pb, Se and Zn, up to 10 µg mL–1. The method was validated with analyses of two standard reference materials and was used for Cd determination in 0.01 mol/L CaCl2 extracts from contaminated kitchen garden soils. The data were compared with those obtained by two other more conventional methods, electrothermal atomic absorption spectrometry (ETAAS) and flame atomic absorption spectrometry (FAAS). The analytical results obtained by the ETAAS and HGAAS were in a good agreement, suggesting the suitability of the method for Cd determination in 0.01 mol/L CaCl2 extracting solution.

Determination of Cd (II), Cu (II), and Pb (II) in Some Foods by FAAS after Preconcentration on Modified Silica Gels with Thiourea

This study describes preconcentration method for determination of Cd (II), Cu (II), and Pb (II) in some food samples. Silica gel was modified with thiourea and characterized by IR and C, H, N, S elemental analysis. Modified silica gel was used as a solid phase extraction for determination of Cd (II), Cu (II) and Pb (II) in tuna fish, biscuit, black tea, rice, kaşar cheese, honey, tomato paste, and margarine samples. The analytical conditions including eluent type, pH of sample solutions, flow rates of sample and eluent solutions, etc. were optimized. The influence of the matrix ions on the involvement of the Cd (II), Cu (II), and Pb (II) were also studied. GBW 07605 tea standard reference material was used for validation of method. The method was successfully applied for the determination of Cd (II), Cu (II), and Pb (II) ions in food samples. The detection limits were in the range of 0.81 μg/L, 0.38 μg/L, and 0.57 μg/L for cadmium, copper and lead, respectively. The relative standard deviations of the procedure were below 10%. The sorption capacities were found as 92 μmol/L Cd (II), 286 μmol/L Cu (II), and 121 μmol/L Pb (II).

Determination of Cadmium in Biological Samples: An Update from 2006 to 2011

: Cadmium has attracted global research interest due to its toxicity, metallomics, and contents in biological samples. From a toxicological and biological point of view, analytical methods for determination of Cd in biological samples are of key importance to subsequent studies. In 2006 we presented a comprehensive review on determination of Cd in biological samples. Since publication of the last review, great progress has been made in this area; for instance, in vivo intracellular imaging of Cd2+, evaluation of in vivo cytoxicity of Cd-based semiconductor quantum dots, and new research progress in Cd-related metallomics. Accordingly, in this review we further summarize the research progress related to Cd determination in biological samples, with a total of 224 references in the period 2006 to 2011. The main contents of this review include toxicity of Cd, biological sample types and sample pretreatment strategies, preconcentration of Cd from biological samples, analytical methods for Cd determination, Cd speciation, bio-imaging of Cd in living cells, and chemical evaluation of the toxicity of Cd-containing quantum dots in biological tissues.

Preparation, characterization, and application of a new thiol-functionalized ionic liquid for highly selective extraction of Cd(II)

A highly selective thiol-functionalized ionic liquid (thiol-FIL) was synthesized and characterized by FT-IR and ESI mass spectroscopy. The capability of thiol-FIL to extract Cd(II), Ni(II), Cr(III) and Pb(II) was evaluated. It is found that thiol-FIL possesses high selectivity for Cd(II), and this has led to a method for determination of Cd(II) by flame atomic absorption spectrometry that is free of interferences by up to a 1,000-fold excess of Na(I), Mg(II), Ca(II), Mn(II), Fe(III), Al(III), Cu(II), Zn(II), Ni(II), Cr(III), Co(II), As(III), Pb(II), and Hg(II). With extraction equilibrium time of 1 min, a good linearity (r = 0.9998) and a detection limit of 0.39 μg L−1 were obtained. The precision (RSD) for 11 replicate measurements of 10 μg L−1 Cd was 1.6%. The method was validated using certified reference materials. The recoveries of cadmium in spiked real samples ranged from 97% to 102%.

Application of Experimental Design to the Optimization of a Wet Acid Digestion Procedure for Cd Determination in Plastic Materials by Atomic Absorption Spectrometry

ABSTRACT A simple and reliable method for Cd determination in plastic materials using optimized wet acid digestion procedure and atomic absorption spectroscopy was developed. In order to obtain the best experimental conditions for plastic digestion, a 27–4 Plackett-Burman design for screening the significant factors and a 24–1 central composite design to optimize the significant experimental variables were carried out. The polyethylene European Reference Material ERM-EC680 with certified Cd content was used in both the screening and the optimization steps. The optimized experimental conditions 0.200 g of plastic material digested with 2 mL nitric acid (30 min, 130°C) followed by 1 mL sulfuric acid (30 min, 140°C). The accuracy and precision was checked using ERM-EC680. The Cd recovery was 101.3% and the relative standard deviation was 5.6%. The limit of detection obtained was 0.23 mg kg−1. The method was applied in the analysis of one PVC plastic material, several commercial packaging materials, and plastic toys.

Development of a sequential injection anodic stripping voltammetry (SI-ASV) method for determination of Cd(II), Pb(II) and Cu(II) in wastewater samples from coatings industry

This paper describes the development and validation of a sequential injection (SI) anodic stripping voltammetry (ASV) method using the hanging mercury drop electrode for accumulation of the heavy metal cations Cu(II), Pb(II) and Cd(II). The method was applied to wastewater samples after proper acid digestion in open vessels to eliminate matrix effects. For a deposition time of 90 s at the flow rate of 10 microl s(-1), the detection limits of the method were 0.06, 0.09 and 0.16 micromol L(-1) for Cd, Pb and Cu, respectively. Under these conditions the linear dynamic range was between 0.20 and 9.0 micromol L(-1) and the sampling frequency was 30 analyses per hour. The relative standard deviation of the method was 3%(n=7) at the concentration level of 2.0 micromol L(-1). The accuracy of the method was evaluated by spiking the samples with known amounts of the metal cations, and by comparison with an independent analytical technique, the inductively coupled plasma atomic emission spectroscopy (ICP-AES). Average recoveries were around of 84%, and the results showed no evidence of systematic errors in comparison to the ICP-AES.

A direct solid sampling electrothermal atomic absorption spectrometric method for determination of trace elements in zirconium dioxide

A direct solid sampling electrothermal atomic absorption spectrometric method for determination of Cd, Co, Cr, Cu, Fe, Li, Mn, Ni and Zn in zirconium dioxide has been developed. Using optimised experimental conditions, very effective in-situ analyte/matrix separation was achieved without any chemical modification. After the measurement, the matrix residue could easily be tipped out from the platform. In the determination of Cr, before sampling, the platform bottom was covered with carbon powder. Quantification was performed using calibration curves measured with aqueous standard solutions pipetted onto the matrix residue from a previous sample run. Sample amounts between 0.5 and 40 mg were applied for each analysis cycle. The accuracy was determined by comparison of the results with those obtained by radiochemical neutron activation analysis and by electrothermal atomic absorption spectrometry using liquid sampling of digests and slurry sampling. For the nine elements assayed, the limits of detection achievable by this method are between 0.06 ng g(-1) (Cd) and 2.3 ng g(-1) (Fe).

Determination of Cd in sonicate slurries and leachates of biological and environmental materials by FI-CV-AAS

An analytical method for Cd analysis in solid samples which combines the ultrasonic slurry formation with cold vapour generation and atomic absorption spectrometry is described. The samples are suspended in HCl and sonicated until homogeneous and reduced particle size slurry formation. Several aspects were studied: acidity of the medium, sonication time, and slurry formation in different matrices. The procedure described permits the use of direct calibration, with KCN addition as masking agent of interfering ions (Cu, Pb, Ni and Zn) present in the environmental matrices. Supernatant analysis of these last samples experimentally shown that preparation of the suspension with 6 mol l −1 HCl concentration led to quantitative extraction of Cd. Biological materials analysis needed the use of the standard addition calibration method due to the high matrix effect observed. Supernatant analysis in biological samples does not give a total Cd recovery for all of them. The detection limits observed for Cd were 0.05 and 0.2 μg l −1 for supernatant and slurry analysis respectively in environmental samples, while in biological samples were 0.2 and 0.6 μg l −1 for supernatant and slurry analysis, respectively. In all case the better precision was obtained for supernatant analysis (3–6%) than slurry analysis (6–12%). The results obtained by analysing different reference materials (sewage sludge, city waste incineration, Antarctic krill and human hair) showed good agreement with the certified value confirming the validity of such a method for Cd determination instead to wet digestion procedures.

Graphite furnace analysis—getting easier and achieving more?

The impact of microwave digestion, hot injection of solutions and chemical modification on the analysis of biological samples by electrothermal atomic absorption spectrometry (AAS) has been assessed. The stabilizing effects of palladium and ruthenium modifiers were compared. Although ruthenium has a higher atom appearance temperature, palladium was the more useful modifier when samples other than water were analysed. When 2 μg of palladium (as PdCl 2) was preconditioned in hydrogen at 500°C, volatile elements were retained at char temperatures up to 1000–1100°C. This allowed similar atomizer programmes to be used for Cd, Cu, Fe, Mn and Pb and accurate determination of these analytes in solutions of reference materials was achieved aqueous standards. Rapid drying of the solutions by hot injection at 120°C reduced the programme time to just over 1 min. A combination of microwave digestion, hot injection of 40% (w/v) HNO 3 solutions and Pd modification produced a rapid and sensitive method for determination of Cd and Pb at sub-μg g −1 levels in vegetable and protein foodstuffs. Palladium modification also proved useful in simultaneous multi-element determination by continuum source AAS. The picogram detection limits obtained for Cr, Mn and Pb were similar to line source AAS values recorded with the same compromise programme. Accurate determination of Cd, Cr, Cu, Mn, Mo and Pb in NIST SRM 1566 Oyster Tissue indicated the potential of continuum source AAS for multi-element determinations. The advantages of palladium modifications were also illustrated for furnace atomic non-thermal excitation spectrometry ( FANES) with a hollow-cathode discharge. The maximum char temperatures of Ag, Ga, Hg, Pb, Sb and Se were increased by 300–600°C in the presence of 1 μg of Pd, although the detection limits were a factor of two poorer.

Determination of Cadmium, Copper, and Lead in Sodium Chloride Food Salts by Flame Atomic Absorption Spectroscopy

A method for determination of Cd, Cu, and Pb in sodium chloride food salt samples has been developed. It consists of extraction in 4-methyl-2-pentanone of the complexes formed with ammonium pyrrolidine dithiocarbamate and further analysis of the extracts by flame atomic absorption spectroscopy. Detection limits in ng/g salt were 0.2 for Cd, 0.7 for Cu, and 10.0 for Pb. The coefficients of variation of 12 independent analyses were 13% for Cd (at a level of 0.4 ppb), 18% for Cu (1.6 ppb), and 5% for Pb (40 ppb). The recoveries were 100 +/- 0% for Cd, 115 +/- 14% for Cu, and 100 +/- 13% for Pb.