Determination Of Copper In Samples Research Articles

Potentiometric Determination of Copper in Herbal Material and Hydrolats of Veronica Species (Family Plantaginaceae)

The aim of our work was an implementation of potentiometric determination of copper in samples of the genus Veronica (family Plantaginaceae). Genus Veronica herbs are widely used in e.g. cosmetic, traditional medicine and food industry. The copper content was potentiometrically analysed in 25 herbal samples of genus Veronica and 12 of their hydrolats. The analysed samples were herbal samples of Veronicas harvested mainly in three Croatian regions – Dalmatia, Lika and Slavonia as well as randomly selected samples of theirs hydrolats. Veronicas’ samples were digested in a microwave oven by using nitric acid and hydrogen peroxide mixture. The potentiometric determination was performed by using commercially available CuISE for Cu2+, by using potentiometric methods previously developed in our laboratory.

Simultaneous Determination of Metals in Cachaça: A Study on Comparison of Multivariate Methods and Quality Control

This study aims to compare multivariate calibration methods developed from data obtained by square wave anodic stripping voltammetry using a hanging mercury drop electrode for simultaneous determination of metals in cachaça, the following metals were studied: copper, zinc and cadmium. Multivariate calibration, partial least squares (PLS) and artificial neural network (ANN) methods were used in previous studies using other electrodes for this determination. In this new study, besides ANN and PLS, a hybrid model that combines PLS and NN, namely PLS-Neural was used. Also, samples of industrial cachaças were incorporated into the study in addition to artisanal samples. The quality of the methods was evaluated in terms of coefficient of determination (R2) and root mean square error of prediction (RMSEP). F test was used for comparing methods at confidence level of 95%. Based on these studies, it was found that although all methods show good results, the method employing neural networks stands out in the determination of copper in samples of cachaça. All methods proved to be fast and relatively low-cost, and they can be used for such analyses.

Copper-selective PVC membrane electrodes based on salens as carriers

Copper(II) selective sensors have been fabricated from polyvinyl chloride (PVC) matrix membranes containing carriers, 2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] meta cresole(I),2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] para cresole(II) and 2,2′-[1,2-ethandiyl-bis(nitrilomethylidine)-bis] ortho cresole(III) as ionophores, dibutyl phthalate (DBP), benzyl acetate (BA), acetophenone (AP) and o-nitrophenyl octyl ether (NPOE) as plasticizing solvent mediators and sodium tetraphenylborate (STPB) and oleic acid (OA) as additives. Best performance was exhibited by the membrane having a composition ionophore (SALEN):PVC:NPOE:OA in the ratio of 4:31:55:10 (w/w). These membranes give a linear potential response in the concentration range (1.0×10 −5 to 1.0×10 −1 M) with a Nernstian slope of 29.2±0.3, 29.7±0.3 and 28.2±0.3 mV/decade of Cu 2+ and limits of detection are 3.6×10 −6 M, 3.1×10 −6 M and 6.3×10 −6 M for salen (I), (II) and (III), respectively. It has a very short response time, less than 10 s, and can be used for at least 9 weeks without any divergence in potential. The copper (II) selective electrode exhibited very good selectivities with respect to alkali, alkali earth and some transition metal ions and could be used in a pH range 3.5–6.5. It was successfully applied for the direct determination of copper in sample of brass and a sample of Wilson’s patient’s urine. This electrode was also used as an indicator electrode in titration of Cu 2+ with EDTA.

Direct copper determination in whole milk, non-fat milk and whey milk by electrothermal atomic absorption spectrometry

A method for the direct determination of copper in samples of whole milk, non-fat milk and whey milk by electrothermal atomic spectrometry (ETAAS) was studied. The fat separation by centrifugation at 3200 rpm and the separation of casein mycelles to obtain the whey milk by ultracentrifugation at 31000 g were investigated. In all cases Mg(NO3)2 was used as chemical modifier and Triton X-100 (0.2% w/v) as emulsifying agent. The optimum pyrolysis temperature was 1500°C. The detection limit was 0.4 μg/1 of copper. The precision was studied for the whole milk and the coefficients of variation (CV) were 5.7, 4.0, 2.4 and 2.8% for 0, 5, 10 and 20 μg/1 of copper added. The accuracy was determined by using the Reference Material Milk A-11 (IAEA) with a certified content of 378.4 ± 24 ng Cu/g; 359 ± 16 ng/g were found. The method was applied to ten cow milk samples, the levels of copper being determined for whole milk, non-fat milk and whey milk. A statistical study was applied and it was concluded that the majority of copper is in the non-fat milk.

Flow-Injection Extraction-Spectrophotometric Determination of Copper with Dithiocarbamates

Several salts of MN-substituted derivatives of dithiocarbamic acid were studied as potential reagents for flow-injection extraction-spectrophoto metric determination of copper. A specific and sensitive method for the determination of copper was developed. Copper is extracted with a chloroform solution of lead diethyldithiocarbamate (DDTC) and the absorbance of the Cu-DDTC complex is measured at 436 nm. Effects of total flow rate, sample volume, mixing and extraction coils length are studied. The detection limit is 0.04 ppm of Cu and calibration graph is linear up to 2 ppm Cu. The method developed was applied to the determination of copper in samples of water and plant materials showing good precision and accuracy.