Cadmium In Biological Samples Research Articles

Development of an analytical method for determination of lead and cadmium in biological materials by GFAAS using Escherichia coli as model substance.

In this work, an analytical method was developed for the determination of lead and cadmium in biological samples using graphite furnace atomic absorption spectrometry. Escherichia coli (E. coli) was chosen as model substance for this purpose as it is readily available in most laboratories and can be quickly and easily prepared with a high turnaround rate. Four different sample preparation methods were initially evaluated with respect to percent recovery, limit of detection, and limit of quantification, and the most promising one was developed further. The final process involving microwave assisted digestion of the sample with nitric acid and hydrogen peroxide showed high recovery, repeatability, and specificity. The process was first applied to lead and then extended for the determination of cadmium in the same E. coli substrates. Finally, to validate the process, a certified references material was analyzed, and the results obtained were evaluated with respect to accuracy by comparing them to the reported ones.

A switchable ionic liquid with polarity swing‐assisted regeneration properties used for the preconcentration of cadmium in biological samples

In the present study the cadmium (Cd) was determined in serum samples of psoriatic patients. The severity of psoriasis was evaluated according to criteria based on standard clinical diagnosis using Psoriasis Area Severity Index (PASI) score. In present study, an innovative tunable green solvent system based microextraction (TSS‐ME) was applied for the enrichment of Cd in acid digested serum samples prior to determination with flame atomic absorption spectrometry. The hydrophobic complex of Cd‐ammonium pyrrolidine thiocarbamate was extracted in a tunable solvent system which was prepared from a polybasic amine (N, N, N′, N′‐tetramethyl‐1, 4‐diaminobutane), decanol and water system. The tunable green solvent system (TSS) which has zero ionic strength was converted to homogeneous monophasic polar hydrophilic phase via exposure to CO2 at different pressure and time duration. Then hydrophobic enriched Cd‐ ammonium pyrrolidine thiocarbamate was back extracted, using HNO3 (0.1 to 0.5 mol L−1) then the second round of TSS‐ME was applied. The acidic aqueous phase enrich with analyte was separated from tunable solvent. The separated TSS was easily reused for up to 10 time for preconcentration purposes without loss of its enrichment character. The smoker and nonsmoker psoriatic patients at PASI >10, have two to three folds higher Cd levels in serum samples than healthy persons.

Application of Cloud Point Extraction for Cadmium in Biological Samples of Occupationally Exposed Workers: Relation Between Cadmium Exposure and Renal Lesion.

Cadmium (Cd) level in blood and urine of soldering iron workers (n=49) and 41 matched healthy controls has been assessed. Cloud point extraction was employed for preconcentration of Cd. The Cd ions formed hydrophobic complex with 9,10-phenanthraquinone monoethyl thiosemicarbazone that was extracted by surfactant-rich phases in the nonionic surfactant Triton X-114. The surfactant-rich phase was diluted with 1 M HNO3 in methanol prior to its analysis by graphite furnace atomic absorption spectrometry. The parameters affecting the extraction efficiency of the proposed method, such as solution pH, amount of complexing agent, surfactant concentration, temperature, and incubation time, were optimized. Under the optimum experimental conditions, the detection limit and the enrichment factor were 0.04 μg L(-1) and 61, respectively. Relative standard deviation of 10 μg L(-1) Cd was less than 3.0%. The accuracy of the method was examined by analysis of certified reference materials. It was observed that soldering iron workers are liable to Cd overload as indicated by higher levels of Cd in blood and urine when compared with the controls. This exposure may lead to kidney damage indicated by elevation of urinary excretion of both N-acetyl-β-D-glucosaminidase and β2-microglobulin.

Ionic Liquid-Based Ultrasound-Assisted Emulsification Microextraction of Cadmium in Biological Samples: Optimization by a Multivariate Approach

An ionic liquid-based ultrasound-assisted emulsification microextraction method was developed for the preconcentration and determination of cadmium followed by flame atomic absorption spectrometry. Cadmium was complexed with 4-(2-pyridylazo) resorcinol, and then extracted into fine drops of 1-butyl-3-methylimidazolium hexafluorophosphate that served as the ionic liquid. The pH, ligand concentration, volume of ionic liquid, sonication time, and temperature were optimized by a multivariate technique. The results showed that concomitant ions did not affect the determination of cadmium. The detection limit and enhancement factor under the optimal conditions were 0.21 micrograms per liter and 92, respectively. The relative standard deviation of 10 micrograms per liter of cadmium was less than 5.0 percent. The validity of the method was investigated by the analysis of a spinach leaves standard reference material. The method was suitable for the preconcentration of cadmium in food and biological samples.

Useful and Fast Method for Blood Lead and Cadmium Determination Using ICP-MS and GF-AAS; Validation Parameters.

In case of clinical analysis, especially in blood lead (Pb-B) and cadmium (Cd-B) determination, the accuracy and precision of the method are crucial. The objective of this article is to present a simple and useful method for Pb-B and Cd-B determination using ICP-MS (inductively coupled plasma-mass spectrometry) as well as GF-AAS (graphite furnace-atomic absorption spectrometry). The principle of the method is based on the deproteinization of blood samples by addition of 5% nitric acid that eliminates the presence of the protein in the samples, thereby excluding the influence of the organic matrix on the result determinations. A comparison of the two techniques ICP-MS and GF-AAS was established for Pb and Cd determinations in the same 40 blood samples collected from lead workers. The results showed that validation parameters for ICP-MS and GF-AAS were similar, however better for ICP-MS for Pb-B determinations. The detection limit (3×SD) for Pb-B determinations for ICP-MS and GF-AAS was, respectively, 0.16 and 1.0 μg/l, and for Cd-B it was, respectively, 0.08 and 0.02 μg/l. Correlation coefficients (rs) for comparable Pb-B and Cd-B determinations, using these two techniques, showed very good statistically significant correlations and were r = 0.9988, P < 0.0001 for Pb-B and r = 0.9949, P < 0.0001 for Cd-B. The obtained results indicate that the method of deproteinization of blood samples is still the best way to eliminate spectral interferences and influence of the organic matter. The elaborated method is especially dedicated to clinical laboratories and determined low concentrations of lead and cadmium in biological samples.

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.

Catalytic solid substrate–room‐temperature phosphorimetry detection for trace cadmium with Cd2+–3.5‐generation polyamidoamine dendrimer–Tween‐80 complex

3.5-Generation polyamidoamine dendrimers (3.5-G-D) emitted strong and stable room-temperature phosphorescence (RTP) on filter paper when Pb2+ was used as a heavy atom perturber. The RTP signal of 3.5-G-D was sharply enhanced upon the formation of 3.5-G-D-Tween-80 micelle compound. The complex Cd2+ -3.5-G-D-Tween-80, generated in the coordination reaction between Cd2+ and the tertiary amidocyanogen on the outer layer of 3.5-G-D in 3.5-G-D-Tween-80 micelle compound, could catalyze KBrO3 to oxidize 3.5-G-D in 3.5-G-D-Tween-80, which caused the sharp quenching of the RTP signal of the system. The phosphorescence intensity change (ΔI(p) ) of the system had a linear relationship with the content of Cd2+. Thus a new catalytic solid substrate-room-temperature phosphorimetry (SS-RTP) for the determination of trace cadmium has been established. This highly selective and sensitive method has been applied to determine trace cadmium in biological samples with a limit of detection (LD) of 1.2 ag per spot (when the sample volume was 0.4 μL per spot, the corresponding concentration was 3.0 × 10(-15) g mL(-1) ), the results agreeing with those obtained by atomic absorption spectrometry. The mechanism of catalytic SS-RTP for the determination of trace cadmium was also discussed.

A preconcentration procedure for the determination of cadmium in biological material after on-line cloud point extraction

In this paper, a method involving on-line preconcentration with cloud point extraction for the determination of cadmium in biological samples is presented. The procedure is based on the sorption of micelles containing Cd(II) ions and the reagent 4-(5'-bromo-2'-thiazolylazo)orcinol (Br-TAO) in a minicolumn packed with polyester. The surfactant Triton X-114 was used in the formation of micelles. After sorption, the Cd(II) ions were desorbed from the minicolumn with acid eluent and determined by flame atomic absorption spectrometry. Parameters influencing the cloud point extraction were studied. The method showed a detection limit of 0.5 μg l(-1) and an enhancement factor of 27. The accuracy was tested by determination of cadmium in certified reference materials (spinach leaves 1570a and tomato leaves 1573a) from the National Institute of Standards and Technology.

Simultaneous determination of trace lead, tin and cadmium in biological samples by a chemical vapor generation-four-channel atomic fluorescence spectrometry dual gas–liquid separator system

A novel, accurate, and precise method is described for simultaneous determination of trace lead (Pb), tin (Sn) and cadmium (Cd) in biological samples by chemical vapor generation (CVG) coupled with non-dispersive atomic fluorescence spectrometry. A chemical vapor generation dual gas–liquid separator system for Pb, Sn and Cd determination assembled with atomic fluorescence spectrometry was proposed. The system consists of two peristaltic pumps as the liquid driver, two gas–liquid separators and an atomic fluorescence detector. In the first gas–liquid separator system, the main Cd vapor and some SnH4 were carried out with reductant solution I, and in the second gas–liquid separator system, the main PbH4 and some SnH4 were carried out with reductant solution II. Cadmium vapor generation was based on hydrochloric acid, cobalt chloride, thiourea and KBH4 concentrations of the first system, SnH4 generation was based on hydrochloric acid and KBH4 concentrations, and PbH4 was based on hydrochloric acid, potassium ferricyanide and KBH4 concentrations of the second system. The operating conditions of the instrumentation were optimized, including the flow rates of carrier and shield gas. The conditions of chemical vapor generation for Pb, Sn and Cd were studied in detail. Under optimized experimental conditions, the blank signal was satisfactorily minimized, giving limits of detection of 0.071, 0.058 and 0.002 ng ml−1 for Pb, Sn and Cd respectively. The relative standard deviation (R.S.D.) was respectively 1.3%, 3.4% and 2.9% for 10 ng ml−1 of Pb, Sn and 2 ng ml−1 of Cd (n = 7). Finally, the proposed method was successfully applied to the simultaneous determination of Pb, Sn and Cd in a series of Chinese certified biological reference materials using simple aqueous standard calibration techniques, with analytical results in good agreement with the certified values.

Determination of Cadmium in Biological Samples

Even though normal exposure levels to Cd may be small, the human body is inefficient at excreting the heavy metal, so it slowly accumulates over the period of a lifetime. Eventually, the Cd level in the body may become toxic and give rise to harmful effects. Cadmium exposure could therefore be linked to diseases associated with aging such as osteoporosis, prostate cancer, and pancreatic cancer. These potential links have driven the development of a myriad of analytical techniques for the determination of Cd in biological samples. Natural biological Cd concentrations are typically low, so preconcentration steps and sensitive instruments are frequently a necessity. In addition, the complex matrices of biological specimens such as blood, urine, serum, and tissue often require a form of matrix modification or separation. This review provides an overview of these methods with 200 references from the literature published between 1995 and 2005. The analytical methods for the determination of Cd in biological samples include: spectrophotometry, atomic emission spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, and electrochemistry. In addition, Cd speciation techniques, using high‐performance liquid chromatography and capillary electrophoresis, are briefly discussed. Amanda C. Davis and Peng Wu contributed equally to this work.

Use of paper capsules for cadmium determination in biological samples by solid sampling flame atomic absorption spectrometry

In this study, a new device was applied for direct solid sampling flame atomic absorption spectrometry. It was used for trace determination of cadmium in biological samples (bovine and chicken liver). Test samples (0.5 to 7 mg) were weighed into small paper capsules, which were introduced into a quartz cell heated by an air-acetylene flame. Operational conditions for the proposed system were evaluated. There was no significant difference between the results obtained with the proposed system and those obtained after digestion and determination by conventional graphite furnace atomic absorption spectrometry. Good agreement was also obtained with the certified values of two reference materials. Background signals were always low. The characteristic mass was 0.34 ng and relative standard deviation was less than 8%. The limit of detection for the proposed procedure was 1.6 ng or 0.23 μg g − 1 if a sample mass of 7 mg was used. Excluding the steps for sample preparation (drying, milling and weighing), the proposed system allows the determination of 40 test samples per hour and it can be easily adapted to conventional flame atomic absorption spectrometers.

Determination of cadmium in biological samples solubilized with tetramethylammonium hydroxide by electrothermal atomic absorption spectrometry, using ruthenium as permanent modifier

The feasibility of Ru as a permanent modifier for the determination of Cd in biological samples treated with tetramethylammonium hydroxide (TMAH) by ET AAS was investigated. The tube treatment with Ru was carried out only once and lasted for about 300 atomization cycles. The pyrolysis and atomization temperatures, 750 °C and 1300 °C, respectively, were chosen from the temperature curves. The sample dissolution procedure was very simple: a sample aliquot was mixed with a small volume of a 25% m/v TMAH solution, the volume was made up to 50 ml and the mixture was kept at 60 °C for 1 h. Six certified biological reference materials were analyzed and the obtained Cd concentrations are within the 95% confidence interval of the certified values, proving the accuracy of the proposed procedure for a variety of biological samples. The calibration curve, with correlation coefficient higher than 0.99, was established for a working range up to10 μg l −1. The precision was good as demonstrated by relative standard deviations below 3%, except for one sample. The limit of detection (3σ) was 0.05 μg l −1 and the characteristic mass was 1.30 pg, obtained in the presence of the Ru modifier.

Cadmium determination in biological samples by direct solid sampling flame atomic absorption spectrometry

A direct solid sampling flame atomic absorption spectrometric procedure for trace determination of cadmium in biological samples has been developed. Test samples (0.05–2.00 mg) were ground and weighed into small polyethylene vials, which were connected to the device for solid sample introduction into a conventional air/acetylene flame. Test samples were carried as a dry aerosol to a quartz cell, placed between the burner and the optical path, which had a perpendicular entrance and a slit in the upper part. The atomic vapor generated in the flame produced a transient signal that was totally integrated within 1 s. The effect of operating conditions and the extent of grinding on the analytical signal were evaluated. Background signals were always low and a characteristic mass of 0.29 ng Cd was obtained. Calibration was performed using different masses of solid certified reference materials. Results obtained for certified and in-house reference materials were typically within the 95% confidence interval of the certified and/or reference value, and the precision, expressed as relative standard deviation, was between 3.8 and 6.7%. The proposed system is simple and it might be adapted to conventional atomic absorption spectrometers allowing the determination of Cd in more than 80 test samples per hour, excluding weighing.

Furnace-fusion system for the direct determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry using tungsten boat furnace–sample cuvette technique

A solid sampling technique using an electrothermal vaporisation device is described. To a small sample cuvette made of tungsten, a solid mixture of a biological sample and diammonium hydrogenphosphate powder as a fusion flux was added. The cuvette was superposed on a tungsten boat furnace, then tetramethylammonium hydroxide solution was injected as a sample decomposition reagent. By resistance heating of the tungsten boat furnace, the cuvette temperature was maintained at a wet-digestion temperature sufficient to decompose the solid sample. After the on-furnace digestion was complete, the temperature was successively elevated up to maximum to generate analyte vapour. The transient cloud of vapour was introduced into the plasma. Since any solid samples could be decomposed to ash completely on the cuvette, the sensitivity was the same as that of aqueous standards. The method was successfully applied to the direct determination of cadmium in biological certified reference materials.

Determination of chromium, manganese, lead and cadmium in biological samples including hair using direct electrothermal atomic absorption spectrometry

Direct analysis of solid samples employing a laboratory assembled electrothermal atomic absorption spectrometer is demonstrated to be a feasible approach for determination of trace elements in plant tissue and hair samples for special applications in plant physiology and biomedical research. As an example, the kinetics of Cr uptake by cabbage and its distribution have been measured as a function of chromium speciation in the nutrient solution. Further, longitudinal concentration gradients of Cr, Pb and Cd have been measured in hair of various population groups exposed to different levels of these elements in ambient and/or occupational environments. The techniques are validated for the determination of these trace elements by neutron activation analysis, dissolution atomic absorption spectrometry and by analysis of certified reference materials. Slurry sample introduction is found appropriate for routine trace element determination and in homogeneity testing. Direct sample introduction is indispensable in the analysis of very small (< 1 mg) tissue biopsy samples in the determination of trace element distributions.

Separation and determination of Cd in biological materials by continuous-flow fluid extraction coupled to flow-injection ICP-AES

An FI-ICP-AES method for the determination of trace levels of cadmium in biological samples is described based on the complexation of the metal ion with 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide (DPTH) and its subsequent on-line extraction into isobutyl methyl ketone (IBMK). The detection limit for cadmium is 8.7 ng/ml and the calibration is linear at least from 10 to 2000 ng/ml. The relative standard deviation for 7 replicate measurements is 3.4% for 100 ng/ml of cadmium. Results from the analysis of some certified biological reference materials are given.

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis[phenyl-(2-pyridyl)methylene]-thiocarbonohydrazide

A systematic study was made of the optimum conditions for cadmium determination in biological samples by ICP-AES after extraction of the metal into methyl isobutyl ketone containing 1,5-bis[phenyl-(2-pyridyl)methylene]-thiocarbonohydrazide. The maximum volume ratio of aqueous to organic phase was 30 ∶ 1 for a single-stage extraction of 99–100% of the metal ion. The detection limit was 0.3 ng/ml cadmium, and the calibration was linear from 0.4 to at least 150 ng/ml. No interferences from the elements commonly found in biological materials were observed. A precision of 2.5% (P = 0.05) at the 2 ng/ml level of the metal was achieved. The accuracy of the method was demonstrated by analysis of three standard reference materials, giving concentrations of 1.90 ± 0.43, 27.1 ± 1.4 and 2.63 ± 0.38 μ/g of cadmium, compared with the certified values of 2.20 ± 0.10, 26.3 ± 2.1, and 2.71 ± 0.15 μg/g, respectively.

Flame atomic absorption spectrometric determination of cadmium in biological samples using a preconcentration flow system with an activated carbon column and dithizone as a chelating agent

A combined flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-solvent elution procedure for the determination of trace amounts of cadmium. The metal was preconcentrated as the dithizonate on a mini-column packed with activated carbon and eluted with isobutyl methyl ketone (4-methylpentan-2-one) into the nebulizer. A preconcentration factor of 40–130, equivalent to 3–12 ml of sample, was achieved by using a time-based technique. The detection limit obtained (3σ) ranged between 0.3 and 1.3 ng ml–1 and the relative standard deviation from 1.3 to 2.4% for a sample volume of 12 and 3 ml, respectively. The results obtained for the determination of cadmium in reference materials testify to the applicability of the proposed procedure to the analysis of biological materials.

The instrumental determination of cadmium in biological samples at nanogram levels with the aid of a Compton suppression system and epithermal neutron activation analysis

Instrumental epithermal neutron activation analysis in conjunction with Compton suppression methods has been used to determine cadmium concentrations in seven biological reference materials. The114Cd(n, γ)115CD(t1/2=53.3h→115mIn(t1/2=4.5h) reaction using the 336.3 keV photopeak was successfully employed to achieve an overall precision between 4%–15% and detection limits between 10–20 ng/g. The accuracy of the results as compared to the certified or compilation values was in excellent agreement.

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide.

An inductively coupled plasma atomic emission spectrometric method for the determination of trace amounts of cadmium after extraction of the metal into isobutyl methyl ketone containing 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is described. The optimum extraction conditions were evaluated from a critical study of the effects of pH, concentration of extractant, shaking time and ionic strength. The detection limit for cadmium is 0.1 ng ml-1 and the calibration is linear from 0.2 to 140 ng ml-1. The relative standard deviation for ten replicate measurements is 2.9% for 2 ng ml-1 of cadmium. Results from the analysis of some certified biological reference materials are given.