Speciation Analysis of Cr(III) and Cr(VI) after Solid Phase Extraction Using Modified Magnetite Nanoparticles

Pichia kudriavzevii (JD2) Immobilized on Acid Activated Perlite as a Biosorbent for Solid Phase Extraction of Cr(III) Determination by AAS (Atomic Adsorption Spectroscopy)

In this study, the preconcentration of Cr(III) ion in Pichia kudriavzevii JD2 immobilized perlite adsorbent by solid phase extraction was investigated. The determination of Cr(III) was performed using flame atomic absorption spectrometry (AAS). The effects of pH, adsorbent amount, recovery solution volume and type, and sample solution flow rate and volume on the recovery efficiency of Cr(III) ions were investigated. Optimized preconcentration conditions for Cr(III) were established using a column technique. The optimal parameters were determined as pH 4, a recovery solution of 2 mol/L HNO3 with a volume of 10 mL, and a sample flow rate of 1-3 mL/min, preconcentration factor 25. Under these conditions, the recovery efficiency of Cr(III) ion on perlite immobilized with Pichia kudriavzevii JD2 was found to be 100.1% ± 0.3% with a 95% confidence level. Analytical variables with a limit of detection (LOD) of 4.8 μg/L and a limit of quantification (LOQ) of 15.8 μg/L were determined for the Cr(III) ion. The accuracy of the method was determined using standard reference materials (SPS-WW1). The relative error of the recovery efficiency was determined to be less than 10%. The method was applied to the determination of Cr(III) in various water samples, such as tap water and mineral waters.

Development of Solid Phase Extraction Method Based on Ion Imprinted Polymer for Determination of Cr(III) Ions by ETAAS in Waters

In this work, a new solid phase extraction method for the determination of chromium species in water samples by electrothermal atomic absorption spectrometry was developed. For selective separation of Cr(III) ions under dynamic conditions, two ion imprinted polymers containing Cr(III)-1,10-phenanthroline complex (Cr(III)-phen) were prepared with the use of one (styrene, ST) or two (styrene and 4-vinylpyridine, ST-4VP) functional monomers. The physicochemical properties of those solid sorbents towards Cr(III) ions were studied and compared. It was found that Cr(III) ions were retained on the Cr(III)-phen-ST and Cr(III)-phen-ST-4VP polymers with high efficiency and repeatability (91.6% and 92.9%, RSD < 2%) from solutions at pH 4.5. The quantitative recovery of the analyte (91.7% and 93.9%, RSD < 4%) was obtained with 0.1 mol/L EDTA solution. The introduction of 4VP, an additional functional monomer, improved selectivity of the Cr(III)-phen-ST-4VP polymer towards Cr(III) ions in the presence of Cu(II), Mn(II) and Fe(III) ions, and slightly decreased the sorption capacity and stability of that polymer. The accuracy of procedures based on both polymeric sorbents was proved by analyzing the standard reference material of surface water SRM 1643e. The method using the Cr(III)-phen-ST polymer was applied for determining of Cr(III) ions in tap water and infusion of a green tea.

Fe3O4–SiO2–graphene oxide–amino acid ionic liquid magnetic solid-phase extraction combined with inductively coupled plasma optical emission spectrometry for speciation of Cr(iii) and Cr(vi) in environmental water

This developed method, based on the combination of functionalized Fe3O4–SiO2–GO–AAIL and ICP-OES, is capable of remarkable selectivity towards Cr(iii).

A dispersive solid phase extraction-based method for chromium(vi) analysis using a Zn–Al layered double hydroxide intercalated with l-aspartic acid as a dissolvable adsorbent

An analytical method for extraction and preconcentration of Cr(vi) in water with DSPE using a Zn–Al LDH intercalated with l-aspartic acid as a dissolvable adsorbent.

Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs) followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V) after oxidation of As(III) to As(V) using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III) was calculated by subtracting the concentration of As(V) from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD) of arsenate were 175 (for 350 mL of sample solution), 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1,n=7), respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.