A simple and very sensitive spectrophotometric method for the direct determination of copper ions

Abstract

A sensitive spectrophotometric method for the direct determination of copper in aqueous samples without a preconcentration step has been developed. It is based on the formation of a yellow complex with the chromogenic reagent di-2-pyridyl ketone benzoylhydrazone (dPKBH) in an alkaline medium. The complex stoichiometry was 1:2 (Cu:dPKBH) and presents maximum absorbance at 370 nm. The influence of chemical variables affecting the behaviour of the system such as pH, concentration of dPKBH, buffer solution and ethanol, order of addition of the reagents and stability of the complex, were evaluated. The molar absorptivity (epsilon) was 3.92x10(4) L mol(-1) cm(-1), and Beer's law was obeyed up to 3 mg L(-1) of copper. The relative standard deviation was 0.46% (n=11) for a sample containing 1 mg L(-1) Cu(II). The limit of detection was 2.5 micro g L(-1) and was therefore more sensitive than the direct methods reported previously. Finally, the method was successfully validated by analysing several real samples with different matrices, such as tap water, natural water or copper alloys, with an average relative error of 2.46%.

Copper dependence of the biotin switch assay: Modified assay for measuring cellular and blood nitrosated proteins

“…Copper and iron are ubiquitous contaminants of labware and buffers; for this reason experiments where the redox chemistry of such metal ions could compromise the validity of results are usually performed with the most effective transition-metal ion chelators (namely DTPA) in the reagents. In regular tap water, copper is often present in the micromolar range [36][37][38][39]. Therefore, the variation of biotin switch results between laboratories and even within laboratories may relate to the variable contamination of copper or other transition metal ions, and the variable incorporation of metalion chelators.…”

Monitoring of copper level in water and soil samples by using liquid–liquid extraction

“…Several analytical techniques, including atomic absorption spectrometry (Pourreza and Ghanemi 2006;Taher et al 2005;Bakireioglu et al 2004), inductively coupled plasma-atomic emission spectrometry (Guo et al 2004;Liu et al 2005), voltammetry (Kumar et al 2005), and spectrophotometry (Pinto et al 2002;Isıldak et al 1999;Jankiewicz et al 1999;Prodromidis et al 1994) have been reported for the determination of copper in various samples. However, spectrophotometric methods are often preferred, as they involve inexpensive instrument and provide high sensitivity with an appropriate chromogenic reagents.…”

“…However, spectrophotometric methods are often preferred, as they involve inexpensive instrument and provide high sensitivity with an appropriate chromogenic reagents. The organic reagents which were used for the determination of copper, such as di2pyridyl ketone benzoylhydrazone (Pinto et al 2002), 4-2,3-dihydro-1,4-phthalazinedione-54-methylpiperidinedithiocarbamate (Isildak et al 1999), sodium(I) diethyldithiocarbamate (Jankiewicz et al 1999), 2,6-dichlorophenolindophenol (Prodromidis et al 1994), etc. However, these methods are not suitable for the routine monitoring of copper in complex matrix samples as the procedures are complicated, report poor sensitivity, and susceptible to pH changes and interferences.…”

Continuous Flow Analysis Combined with a Light-Absorption Ratio Variation Approach for Determination of Copper at ng/ml Level in Natural Water

“…12 Besides, the stripping voltammetry, 13 spectrophotometry, 14,15 spectrofluorophotometry, 16 and chemiluminescence 17 24 and other methods are recently reported. All of them have played important roles in improving the analytical sensitivity, selectivity and detection efficiency.…”