Determination Of Chromium Research Articles

Analyte Extension Method Validation of Elemental Analysis Manual Method 4.7 for Six Additional Elements, Cobalt (Co), Strontium (Sr), Thallium (Tl), Tin (Sn), Uranium (U) and Vanadium (V).

An interlaboratory study was conducted at the U.S. Food and Drug Administration's (FDA) Northeast Food and Feed Laboratory (NFFL) and the Center for Food Safety and Applied Nutrition (CFSAN) with the purpose to expand FDA Elemental Analysis Manual (EAM) method 4.7 (Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion) to include new analytes (1). The goal of the study was to demonstrate the performance of FDA EAM method 4.7 when analyzing new analytes cobalt (Co), strontium (Sr), thallium (Tl), tin (Sn), uranium (U) and vanadium (V). This analyte extension method validation of EAM 4.7 for six additional elements, Co, Sr, Tl, Sn, U and V followed all guidelines for a Level 2 or single laboratory validation and met all acceptance criteria for analyte extensions as per the Guidelines for the Validation of Chemical Methods (3). As per EAM 4.7 (1), this study followed the procedures and used specified equipment operated under recommended conditions. The analyte extension method validation was performed per protocol and with no deviations. All quality control (QC) requirements for this analyte extension method validation of EAM 4.7 passed as evidenced by the analytical data. The results presented demonstrate accuracy, linearity and precision by successful analyses of method blanks, matrix spikes, unfortified test samples and reference materials. The data analyzed met each of the validation requirements for each analyte in all representative matrices. The study showed that the new analytes performed satisfactorily using EAM 4.7 for total acidic extractable elemental analysis of food according to FDA's guidelines (3). The method met or exceeded the performance criteria.

Determination of chromium in foodstuffs by using novel adsorbent in vortex assisted-dispersive solid phase micro-extraction method: An application of multivariate techniques

A new graft copolymer composed of polystyrene and polylinoleic acid (PLinas) with the sodium salt of iminodiacetate (Ida) was synthesized and used as an adsorbent. The vortex-assisted dispersive solid-phase micro-extraction (VA-dSPµE) method was used for the extraction and pre-concentration of chromium. Multivariate methodologies, such as factorial design and 3D surface plots, were applied for screening and optimizing effective extraction parameters. The influence of diverse analytical parameters, such as pH, sample volume, and interfering ions, on the extraction of chromium was studied. The calibration standard curve exhibited a linear range from 0.01 to 0.50 μg L−1. The relative standard deviation and limit of detection were found to be 1.65 % and 0.003 μg L−1, respectively. Extraction recoveries were found in the range of 96 to 99 % by using certified reference materials (CRMs). The adsorbent capacity of PLinas-Ida was found to be 112 mg g−1. The VA-dSPµE method demonstrated its effectiveness in the pre-concentration and determination of chromium within samples of foodstuffs by graphite furnace-atomic absorption spectrometry (GF-AAS).

A honeycomb-like micro-needle sensor with gold nanoparticles embedded for the determination of hexavalent chromium in seawater

As one of the most toxic heavy metals, hexavalent chromium (Cr(VI)) is a typical environmental pollutant that directly affects human health. In this work, a novel micro-needle sensor with honeycomb-like structure and embedded gold nanoparticles was proposed for the stable and sensitive determination of Cr(VI). The honeycomb-like structure provided larger specific surface area to support more gold nanoparticles which exhibited excellent catalytic activity towards the electrochemical reduction of Cr(VI) to Cr(Ⅲ). In addition, gold nanoparticles were embedded into the holes of the honeycomb-like structure, which can effectively prevent them from falling off from the electrode surface due to the protection of the holes. Combining the honeycomb-like structure of micro-needle electrode with the excellent catalytic activity of gold nanoparticles, the fabricated sensor exhibited outstanding stability and sensitivity for the cathodic stripping determination of Cr(VI). A linear range of Cr(VI) from 0.5 to 300 μmol/L was obtained, with the detection limit of 0.15 μmol/L. The recovery of the sensor for the determination of hexavalent chromium in seawater samples was also investigated. Moreover, the sensor might be further adapted for the determination of other heavy metals with different nanoparticles embedded.

Method Development and Optimization of Liquid-Liquid Microextraction Based on the Decomposition of Deep Eutectic Solvent for the Determination of Chromium (VI) in Spinach: Assessment of the Greenness Profile Using Eco-scale, AGREE, and AGREEprep

A simple, effective, and ligandless liquid-liquid microextraction (LLME) procedure based on the decomposition of hydrophobic deep eutectic solvents (HDES) was developed for the separation and pre-concentration of chromium (VI) ions in spinach leaves, before the determination by flame atomic absorption spectrophotometry. In the proposed study, the first stage involved the leaching of chromium (VI) from spinach leaves with 0.1 M Na2CO3, and in the second stage, chromium (VI) extract was preconcentrated with the LLME procedure using a DES prepared from the combination of DL-menthol and formic acid as a chelating agent and extraction solvent. The DES decomposed in an aqueous donor phase resulting in the dispersion of menthol and extraction of Cr (VI) ions. Under optimal experimental conditions, the limits of detection (LOD) and quantification (LOQ) were 0.63 and 2.1 µg L−1, respectively. The relative standard deviation (RSD) was less than 7%, and the pre-concentration factor (PF) was found to be 31.25. The accuracy of the present methodology was tested by recovery experiments. The greenness of the developed method was assessed using three quantitative green metrics tools: Analytical Eco-scale, AGREE, and AGREEprep, with only Analytical Eco-scale qualifying the proposed method as green.

Quantitative determination of Hexavalent chromium using a microtiter plate: Analytical performance, operational efficiency, and fixation of a colorimetric reagent in the plate wells

Efficient and sensitive trace determination of Cr(VI) in small sample volumes is an important issue for environmental protection and the sustainable development of industries. A microtiter plate and a microplate reader have been applied to the colorimetric determination of Cr(VI) using 1,5-diphenylcarbazide (DPC) as indicator, to realize an efficient method with low detection limits. The DPC reagent was fixed on the plate well and the time for color development was significantly reduced (<1 min) compared to conventional methods by using small volume reaction vessel which made it possible to perform determinations of Cr(VI) in a short period of time. The lower limit of quantification of 0.021 mg/L obtained with this method is better than that of the microplate method reported previously, and is comparable to general analytical methods with large sample volumes. In addition, when the chromogenic reagent is fixed to the plate with a water-soluble polymer, the lower limit of quantitation is comparable as that of the unfixed reagent. This results in improved instrument portability and more efficient analytical operations.

Speciation of Chromium by Magnetic Solid Phase Microextraction Using an Activated Charcoal-Molybdenum (IV) Selenide-Magnetite Composite with Flame Atomic Absorption Spectrometric (FAAS) Detection

A simple and sensitive magnetic solid phase extraction (MSPE) method was developed for the separation-preconcentration and speciation of Cr in water samples. The system is based on the adsorption of Cr (VI)-ammonium pyrrolidinedithiocarbamate (APDC) complex on the activated charcoal@MoSe2@Fe3O4 composite. Total chromium has also been determined after the conversion of Cr (III) to Cr (VI) by oxidation with KMnO4. Cr (III) was determined as the difference between the total content of the Cr and Cr (VI). For quantitative recoveries, the effects of solution pH, adsorbent amount, volume of the sample, ligand volume, eluent type, and volume and effect of foreign ions were investigated. The limit of detection and limit of quantification for Cr was 0.36 ng mL−1 and 1.19 ng mL−1, respectively. The procedure was applied for the determination and speciation of chromium in water samples.

Determination of ultra-trace level Cr(vi) in seawater using large-volume direct injection by LC-ICP-MS with in-line matrix elimination

A method to improve the sensitivity of LC-ICP-MS for the determination of hexavalent chromium (Cr(vi)) in seawater by using the large volume injection and in-line matrix elimination.

Chitosan-adhered graphene/nano iron tetroxide carbon paper electrode for the detection of hexavalent chromium

A modified electrode for rapid determination of hexavalent chromium in solution in a three-electrode system was prepared.

Online spectrophotometric pre-concentration and trace determination of chromium(VI) by immobilized Bacillus cereus on silica gel

Online spectrophotometric pre-concentration and trace determination of chromium(VI) by immobilized Bacillus cereus on silica gel

Determination of hexavalent chromium in textiles of daily use by ion chromatography and dermal risk assessment

The determination of hexavalent chromium in textiles and clothes is challenging since during extraction, the original oxidation state should not be altered. Since, as a matter of fact, current analytical methods are focused only on total chromium determination, the purpose of this research is to develop a reliable analytical method for the determination of Cr(VI) in textiles and tissues of daily use for a reliable application of risk analysis models, which are usually based on total Cr data.After optimization, a 0.0025 M Na3PO4 extraction solution was selected for the extraction of Cr(VI) from textiles. This solution minimizes possible interconversion redox reactions and interference, and provides good extraction recoveries (88.4 ± 2.5% - 105.5 ± 0.6 %, according to Cr(VI) concentration) and quantitation limits (0.017 mg/kg), fully complying the current limits set for Cr(VI) in textiles in contact with skin, and for leachable Cr(VI).The developed method was validated investigating intra-day repeatability (n = 10) and inter-day repeatability (n = 30) which were below 12%, and matrix effect which was below 6% confirming the precision of the method and the negligibility of a matrix interference during the whole analysis. The method, which was proved to be suited also for bioaccessibility studies in saliva and sweat, was applied to the analysis of tank top, coloured paper napkin, polyamide tights, panties, highlighting Cr(VI) content in the panties only at very low concentration (0.028 mg/kg). As verified by ECHA and US EPA approaches, this amount does not pose a non-carcinogenic risk for human health. As regards carcinogenic risk, considering both adult and child exposure, the dermal contact with the panties poses an acceptable risk (R ≤ 10−6).

Fast chromium determination in pharmaceutical tablets by using electrochemical sensors: Preparation and comparison

In the present paper, three electrodes were prepared with the aim of detecting chromium (III) in pharmaceutical tablets and comparing their capabilities and efficiency. At first, N-(pyridine-2-ylcarbamothioyl) benzamide (NP2YCTB) was synthesized and characterized by 1H NMR, FTIR, and 13C NMR spectroscopy methods. Then, it is used as a sensing material to prepare three types of chromium potentiometry sensors including solid-state electrodes (SSE), coated wire electrodes (CWE) as asymmetric electrodes, and liquid membrane electrodes (LME) as symmetric electrodes. The responses of all electrodes were Nernstian. Field-emission scanning electron microscopy was utilized to investigate the liquid membrane morphology. The presence of chromium (III) in the membrane was proved using Energy-dispersive X-ray spectroscopy and the coordination of NP2YCTB heteroatoms with chromium (III) was confirmed by Fourier transform infrared spectroscopy. The limit of detection for SSE (3 × 10−9 mol/L) was enhanced compared with LME (7 × 10−6 mol/L) and CWE (3 × 10−7 mol/L). The response time of electrodes was very short so it was about 5–6 s for LME and CWE and 5–8 s for SSE. The sensors were used for the potentiometric determination of chromium (III) in pharmaceutical tablets and in the potentiometric titration of it with EDTA.

Determination of Molybdenum, Nickel, and Chromium in Low-alloy Steels Using Laser-induced Breakdown Spectroscopy Assisted with Laser-induced Fluorescence and Discrete Wavelet Transform

Determination of Molybdenum, Nickel, and Chromium in Low-alloy Steels Using Laser-induced Breakdown Spectroscopy Assisted with Laser-induced Fluorescence and Discrete Wavelet Transform

Enhanced Accuracy for the Determination of Chromium in Steel by Laser-Induced Breakdown Spectroscopy (LIBS) and Extreme Random Tree (ERT)

The content of chromium (Cr) affects the mechanical and wear resistance of steel. Hence, the determination of Cr in steel is of great significance to determine the quality. In this study, a new method based on laser-induced breakdown spectroscopy (LIBS) combined with extreme random tree (ERT) is reported to determine Cr in steel. First, the Cr I 425.43 nm line was selected for univariate quantitative analysis. Next, multivariate analysis of Cr was performed using partial least squares regression (PLSR), random forest (RF), and ERT. The abilities of the models for the determination were validated by the fitting coefficient (R 2), root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP), and average relative error (ARE). The R 2, RMSEC, RMSEP, and ARE values of ERT were 0.9984, 0.0274 wt.%, 0.0299 wt.%, and 2.43%, respectively. Compared with the univariate model, PLSR, and RF models, the R 2 of ERT increased by 0.1317, 0.0306, and 0.013, respectively; RMSEC decreased by 0.0987, 0.0955, and 0.0174 wt.%; RMSEP decreased by 0.1463, 0.0876, and 0.002 wt.%; and ARE decreased by 17.88%, 16.98%, and 5.95%, respectively. The results show that combining LIBS with the ERT model for multivariate analysis improves the elemental analysis of steel.

Effect of the Grain Refinement of Iron(III) Hydroxide Precipitation for Removal of Chromium(III) by Iron(III) Hydroxide Coprecipitation Method for Chromium(VI) Determination

Effect of the Grain Refinement of Iron(III) Hydroxide Precipitation for Removal of Chromium(III) by Iron(III) Hydroxide Coprecipitation Method for Chromium(VI) Determination

Determination of Cr and Pb in edible vegetable oils by coupling of extraction induced by emulsion breaking with dispersive liquid-liquid microextraction followed by flame atomic absorption spectrometry detection

This study presents an efficient method for the determination of chromium and lead in various edible vegetable oils by combination of extraction induced by emulsion breaking (EIEB) and dispersive liquid-liquid microextraction (DLLME) followed by flame atomic absorption spectrometry (FAAS) detection. The technique relies on the formation of a water-in-oil emulsion, achieved by introducing an extraction phase containing 20% (w/v) Triton X-100 and 1% (v/v) nitric acid. The metal ions were extracted to the aqueous phase through centrifugation of the resulting emulsion. Subsequently, the collected aqueous phase was mixed with dithizone, and the pH of solution was adjusted at 8 and 9 for Cr and Pb, respectively. Finally, DLLME was applied to concentrate the extracted metal ions, which were then quantified using FAAS. Various factors affecting the extraction efficiency of selected the metal ions were optimized using one-variable-at-a-time method. The estimated limit of quantifications were 5.0 µg/kg and 2.0 µg/kg for lead and chromium, respectively. The standard addition method was used to construct the calibration curves. The calculated relative recoveries for the spiked oil samples ranged from 94.0% to 98.0% for chromium, and from 92.0% to 96.4% for lead. The results showed that the proposed technique offers a simple and efficient analytical methods for the determination of lead and chromium in oil samples.

Comparative Studies on Spectrophotometric Determination of Selected Heavy Metals in Environmental and Biological Samples with Synthetic Phenylhydrazones as Chromogenic Reagents

This work involves a comparative study on a simple, sensitive, selective and non-extractive Uv- Vis spectrophotometric method for the determination of cadmium, lead, chromium and arsenic in biological, soil and water samples using synthesized and characterized phenylhydrazones; [glutaraldehyde phenylhydrazone (GPH) and acetylpyridine-2,4-dinitrophenylhydrazone (APDH)] as the chromogenic reagents was developed. GPH and APDH were synthesized as new chromogenic analytical reagents for the direct UV-Vis spectrophotometric determination of the selected metals of interest in a slightly acidic pH of 6.5-7.5 and 20% dimethylformamide (DMF) solution to give stable coloured metal-ligand complexes. The reactions were instantaneous; the wavelengths of maximum absorptions were followed spctrophometrically and noted. The analytical properties of the reagent APGH on the metals (Cd, As, Pb, and Cr) revealed the wavelength of maximum absorption ranged between 385.0 (Cr) to 440.0nm for (Pb). The reagent APDH had molar absorptivities (L mol -1 cm -1 ) ranging from 2.006 x 10 4 (Pb) to 2.407 x 10 4 (Cd), a mole ratio of metal to ligand of 1:1, a detection limit (µg/g) ranging from 0.3272 (As) to 0.4456 (Cd) and the metal-ligand complex was stable for 0-36 hours. The reagent GPH revealed a wavelength of maximum absorption between 360.0 (Cr) to 395.0 nm for (Pb and As) at a working pH of 6.5 to 7.5 room temperature (37°C). The reagent GPH had a molar absorptivities (L mol -1 cm -1 ) ranging from 2.213 x 10 4 (Pb) to 2.460 x 10 4 (As), a mole ratio of metal to ligand of 2:1, the detection limit (µg/g) ranging from 0.3432 (As) to 0.5250 (Pb) and the metal-ligand complex was stable for 0-48 hours. Both reagents had a Beer’s law validity range (mgL -1 ) of 0.001 to 100. The Sandell’s sensitivities (µg/cm 2 ) ranged from 0000409 (As) to 0.00499 (Pb) for APDH and 0.00406 (As) to 0.00452 (Pb) respectively. Large excess of cations and anions as possible interferences up to 1

Highly sensitive determination of total chromium in seawater by inductively coupled plasma-mass spectrometry with sample introduction of ultrasound nebulization-dielectric barrier discharge vapor generation

A highly sensitive method for total chromium (Cr) determination in seawater by inductively coupled plasma-mass spectrometry (ICP-MS) with sample introduction of ultrasound nebulization-dielectric barrier discharge (UNDBD) vapor generation is proposed in this work. Using this sample introduction system, the sensitivity of Cr is increased 56 folds compared with the common pneumatic nebulization sample introduction system, and the interferences from the seawater matrix at 500 mg L−1 level are all found negligible for trace Cr determination. With these advantages, this method is proved to be applicable for rapid and accurate determination of total Cr in seawater, requiring only the oxidation of Cr(III) to Cr(VI) and dilution steps, without the matrix separation steps. The experimental parameters for Cr determination including the Cr species, the sample volume, the spray distance, the carrier gas flow rate, and the solution pH are evaluated in detail. Under optimal conditions, the relative standard deviation for Cr is 1.9% at the concentration of 5 μg L−1 and the detection limit for Cr is 0.004 μg L−1. The proposed method is thus successfully applied to determine total Cr in certified reference seawater samples and real seawater samples, all with satisfactory results. Comparing with other sample introduction systems, the proposed UNDBD sample introduction system not only has a much lower detection limit for Cr, but also can be operated with low sample consumption (40 μL) and low power (70 W).

Separation, speciation and quantification of both chromium (VI) and chromium (III) in tanned leather samples: a comparative study and validation of analytical methods

In the present work, a comparative study of analytical methods for the simultaneous and quantitative determination of trivalent and hexavalent chromium is presented. For the analysis by ion chromatography-inductively coupled plasma-mass spectrometry, two different columns were tested, as well as different mobile phases and different pH of the samples. The optimized analytical method permitted the separation of Cr(III) and Cr(VI) using 75 mmol/L NH4NO3 pH 3 as chromatographic eluent. The method was validated and applied to real samples, allowing the determination of both species simultaneously, even when there is a huge difference of concentration between Cr(III) and Cr(VI). Limit of detection and limit of quantification for Cr(III) were found to be 0.016 and 0.054 upmug/L (0.3 and 1.1 upmug/kg), respectively, and for Cr(VI) 0.13 and 0.43 upmug/L (7 and 22 upmug/kg), respectively. Possible species interconversions were monitored through the use of chromium isotopic standards, which confirmed that the optimized methodology preserves chromium speciation during extraction and analysis. Fourier-transform ion cyclotron resonance-mass spectrometry permitted the structure elucidation of the complex formed during ethylenediaminetetraacetic acid extraction.Graphical

Electrochemical Determination of Chromium(VI) with Au/UiO-66 Modified Glassy Carbon and Screen-Printed Electrodes by Linear Sweep Voltammetry (LSV)

The development of rapid methods for in situ chromium determination in natural water is important. A new nanocomposite was fabricated by impregnating gold nanoparticles onto archetypical UiO-66 metal organic frameworks and modifying glassy carbon electrodes (Au/UiO-66/GCE) for rapid Cr(VI) determination in water by linear scanning voltammetry (LSV). The Au/UiO-66/GCE showed excellent linearity in the 100 to 1200 ppb Cr(VI) concentration range, with 0.07132 µA/ppb·cm2 sensitivity and a 11.73 ppb detection limit. When potential interfering metals were added, including Cr(III) and Fe(III), the electrochemical detection signal of Cr(VI) did not meaningfully change, suggesting that Au/UiO-66/GCE has good selectivity. A Au/UiO-66/screen printing sensor was also developed for Cr(VI) and used with a portable, handheld electro-analyzer. The Au/UiO-66 nanocomposite—used as an active substrate for electrode modification—was stable, interference-free, and fast, showing promise for the practical determination of Cr(VI) species.

Colorimetric detection of chromium (VI) via its instigation of oxidase-mimic activity of CuO.

Extensive use of chromium makes it one of the major pollutants of water resources. Chromium (VI) in particular is toxic and has detrimental health effects. Because of its high toxicity a tolerable concentration limit of chromium (VI) in drinking water has been recommended. Here we report a colorimetric method for determination of chromium (VI) in water based on the oxidase-like activity of solvothermal synthesized copper oxide. The particles have been characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). Using 3, 3', 5, 5'- tetramethylbenzidine (TMB) as a chromogenic substrate, CuO exhibited a pronounced oxidase-like activity in the presence of chromium (VI). This method enables successful colorimetric detection of chromium (VI). It demonstrated excellent selectivity for detection of chromium (VI) ions against potentially interfering ions. The method's feasibility to real sample analysis has been proven by testing tap water. Hence, we anticipate that the method can be successfully applied for analysis of chromium (VI) in environmental samples.