Use of dicyclohexano-18-crown-6 to separate traces of silver(I) from potassium thiocyanate in hydrochloric acid media, and determination of the silver by atomic absorption spectrometry

Abstract

Solvent extraction with 0.05 mol L(-1) dicyclohexano-18-crown-6 (DC18C6) in 1,2-dichloroethane, coupled with flame atomic absorption spectrometry (AAS), has been investigated as a new method for separation of trace amounts of silver(I) from 0.05 mol L(-1) potassium thiocyanate in 1.0 mol L(-1) hydrochloric acid media and quantification of the amount of silver present. The method is based on the formation of an extractable ion-association product, [DC18C6.K](+)[Ag(SCN)(2)](-), with a metal-to-crown ether ratio of 1:1 (as derived from slope analysis data). Stripping of the extracted silver(I) in the 1,2-dichloroethane phase was achieved within 5 min by use of 3.0 mol L(-1) potassium thiocyanate. Reducing the concentration of acid in the sample solution to 0.1 mol L(-1) improved the preconcentration factor severalfold. Excellent tolerance of the proposed method to the presence of foreign ions in solution with silver(I) was demonstrated. A detection limit of 13 ng mL(-1) was derived from the mean value of the blank plus three times its standard deviation. The method was used to determine traces of silver(I) after separation from gold(III), platinum(IV), and palladium(II) matrices on the basis of extractability differences with 18-membered crown ethers under specified conditions. The efficiency of the adopted ion-association mechanism for silver(I) extraction was apparent from the average recovery of 96% for spiked standards by use of the back-washing technique. The proposed extraction procedure was applied to the determination of traces of silver(I) in a selection of chemical reagents.

Magnetomotive room temperature dicationic ionic liquid: A new concept toward centrifuge-less dispersive liquid–liquid microextraction

“…Various extraction and microextraction techniques such as coprecipitation [9], liquid-liquid extraction (LLE) [10], solid-phase extraction (SPE) [7,11] dispersive liquid-liquid microextraction (DLLME) [18], ultrasound assisted emulsification solidified floating organic drop microextraction (USAE-SFODME) [8,19] and cloud point extraction (CPE) [12] have been used for separation and preconcentration of gold and silver.…”

“…Some analytical techniques are available for determination of trace amounts of Au and Ag in geological and environmental samples such as flame atomic absorption spectrometry (FAAS) [6,7,8,[9][10][11][12], neutron activation [13], spectrophotometry [14], electrochemical methods [15], inductively coupled plasma mass spectrometry (ICP-MS) [16] and electrothermal atomic absorption spectrometry (ETAAS) [17][18][19].…”

Separation of trace amount of silver using dispersive liquid–liquid based on solidification of floating organic drop microextraction

“…It clearly shows that the proposed method has good sensitivity and precision. Also, the obtained LOD by this method are better than those obtained by other methods [4,[29][30][31][32][33]. Our method has a little worse LOD and a main advantage over the displacement dispersive liquid-liquid microextraction method (D-DLLME) [34].…”

“…A comparison of the proposed DLLME-SFO method and some of the published methods for extraction and determination of silver are summarized in Table 4 [4,[29][30][31][32][33][34]. It clearly shows that the proposed method has good sensitivity and precision.…”

The study of ligand properties of crown ethers (18-crown-6 and dibenzo-18-crown-6) when interacting with RhCl3 • nH2O in aprotic and proton solvents

“…Исследования CR показало, что наиболее интересным является не столько синтез, а их лигандные возможности в процессах комплексообразования с катионами или нейтральными молекулами [2][3][4][5][6][7]. В первых работах C.J.…”