A preconcentration procedure for copper, nickel and chromium ions in some food and environmental samples on modified Diaion SP-850

An environmentally friendly and novel amine-based liquid phase microextraction of quercetin in food samples prior to its determination by UV-vis spectrophotometry

A novel and environmentally-friendly method, which includes determination of trace amounts of quercetin in samples by using UV-vis spectrophotometry after enrichment with amine-based liquid phase microextraction (LPME), has been developed. As extraction solvent, N,N-dimethyl-n-octylamine has been used and the quercetin concentration in extraction phase was determined by UV-vis spectrophotometry at 382.5 nm. Important analytical parameters such as pH, extraction solvent type and volume, sample volume, extraction time were optimized by the method. Quercetin in the sample solution was extracted to 200 μL of N,N-dimethyl-n-octylamine phase at pH 4.0. The detection limit (LOD) and the quantitation limit (LOQ) values for quercetin were calculated as 0.07 μg·mL^-1 and 0.24 μg·mL^-1, respectively. Accuracy studies for the food samples was carried out by addition and recovery experiments. The developed method has been successfully applied to different food samples including spinach, green pepper, red onion and dill weed.

A novel polyvinyl chloride-membrane optical sensor for the determination of Cu(2+) ion based on synthesized (N'(1)E,N'(2)E)-N'(1),N'(2)-bis(pyridine-2-ylmethylene)oxalohydrazide: experimental design and optimization

A copper (Cu(2+)) ion-selective bulk optode was constructed by using (N'(1)E,N'(2)E)-N'(1),N'(2)-bis(pyridine-2-ylmethylene)oxalohydrazide as ionophore and NaTPB in DBP matrices. Central composite design under response surface methodology was applied for the optimization of variables including pH, amount of ligand, amount of additive and response time which significantly affect the response of proposed sensor. At optimum specified conditions, the high stability, reproducibility and relatively long lifetime of the optical sensor suggest its ability for accurate and precise monitoring of Cu(2+) ion content in various real samples over a concentration range of 1.6×10(-6) to 3.17×10(-5)molL(-1) with a limit of detection of 8.1×10(-7)molL(-1) during response time 6.9min. The proposed optical sensor was successfully applied for the determination of Cu(2+) ion in tap water and different samples.

Spectrophotometeric determination of trace amounts of Al3+ ion in water samples after cloud point extraction using quinizarin as a complexing agent

In this study, cloud point extraction was used for the preconcentration of Al(3+) ion after the complex formation with 1,4-dihydroxy-9,10-anthraquinone (Quinizarin [QUIN]), and subsequent analysis by spectrophotometeric method, using Triton X-114 as surfactant. The optimal extraction and reaction conditions were studied (i.e., pH = 5.5, 0.1 mM QUIN, Triton X-114 = 0.1% (w/v)), and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and enrichment factors) were obtained. Linearity was obeyed in the range of 3.33-166.67 ng ml(-1) of Al(3+) ion. The detection limit of the method was 2.09 ng ml(-1) for Al(3+) ion. The interference effect of some anions and cations was also tested. The method was applied to determine Al(3+) ion in water samples.

Preconcentration procedures for the determination of chromium using atomic spectrometric techniques: A review

Chromium is one of the regulated toxic metals in the environment. Naturally, this element exists mainly in two oxidation: Cr(III) and Cr(VI). In general, Cr(VI) is more toxic than Cr(III). Cr(VI) affects human physiology, accumulates in the food chain and causes severe health problems ranging from simple skin irritation to lung carcinoma. Hence, the determination of chromium traces as well as its speciation in environmental samples is a very important task. In recent years, several preconcentration methods such as coprecipitation, liquid-liquid extraction, dispersive liquid-liquid microextraction, cloud point extraction, and solid phase extraction have been developed and widely used. The aim of this study is to review the recent literature (mainly last 5 years) on the preconcentration technologies those have been used in chromium removal before the determination step by atomic spectrometric techniques. Their advantages and limitations in application are also evaluated.

Sorbent extraction of 4-(2-thiazolylazo) resorcinol (TAR)-metal chelates on Diaion SP-850 adsorption resin in order to preconcentration/separation

A sensitive and simple separation-enrichment technique for the determination of trace amounts of some metal ions was described. By the passage of aqueous samples including Fe(III), Cu(II), Ni(II) and Co(II) ions-4-(2-thiazolylazo) resorcinol (TAR) chelates through Diaion SP-850 column, metal chelates adsorb quantitatively and almost all matrix elements were passed through the column to drain. Quantitative recoveries for analyte ions were obtained at pH 6 at 3 ml/min flow rate of sample solution in 0.5 g Diaion SP-850 filled glass column. The investigations were also carried out on the interferences from other concomitant ions in the sorption process. After optimization, a preconcentration factor of 60 and a recovery values as % higher than 95 were achieved. The detection limit (N=10, 3 sigma) for Fe(III), Cu(II), Ni(II) and Co(II) were found as 3.6, 1.1, 2.8 and 2.3 microg l(-1), respectively. The applications to the determination of iron, copper, nickel and cobalt in real samples and the validation of the analytical methodology employing NIST SRM 1549 milk powder, NIST RM 8433 Corn Bran and BCR 144R Sewage sludge of domestic origin as certified reference materials were performed.