Novel Plastic Chromium(III)‐Ion Selective Electrodes Based on Different Ionophoric Species and Plasticizing Solvent Mediators

Abstract

Different ionophoric species, viz.: 18-crown-6 (18C6), dibenzo-18-crown-6 (DB18C6) and calix [6]arene (CAX), as electroactive materials, with 2-nitrophenyloctylether (2-NPOE), bis(ethylhexyl)sebacate (DOS), dioctyl phthalate (DOP), and didecyl phthalate (DDP) as plasticizing solvent mediators were used to construct Cr 3þ selective electrodes in a PVC matrix in the ratio (w/w) PVC: ionophore: plasticizer (60 : 2 : 120). Seven electrodes out of the fabricated 12 electrodes, gave best results in terms of working concentration range (1.0 Â 10 À5 À 1.0 Â 10 À1 M) with a close to Nernstian slope of 18.5 and a Nernstian slope of 20.0 mV/decade of activity. The usable pH range of the sensors is 4.0 -7.0. The detection limit of the selected electrodes is 1.0 Â 10 À7 M. The response time of the sensors is 8 -35 s, depending on the concentration of Cr 3þ used. The selectivity coefficient values indicate that the electrodes are highly selective for Cr 3þ over a number of other cations except Pb 2þ and Na þ (for some electrodes). The electrodes have successfully been used to determine Cr 3þ in certified and real alloys and in effluents of electroplating shops with a precision as relative standard deviation (RSD) < 3%, for each of the proposed Cr 3þ -ion selective electrodes. The results obtained by the proposed ISEs are in good agreement with the results obtained by direct flame AAS method.

Functionalization of micro- and nano-apertures with chromate-selective solvent polymeric membrane

“…Furthermore, a mere seven percent difference was obtained when comparing the slopes associated with these two optimal recipes, and the LODs fell within an order of magnitude. The results reported are consistent with the majority of alternative solvent polymeric membrane recipes targeting chromium ions (including Cr 3+ , HCrO 4 − , and CrO 4 2− [29-33], as most of these consist of 1% ionophore recipes with the exception of that of Aradkani, et al [34] and Singh, et al [35] which call for a 7% and 10% ionophore recipe, respectively. It was desirable in this study, however, to use higher concentrations of ion exchanger to help reduce bulk resistance.…”

“…1, for the CWEs, nanoscale ISEs, and microscale ISEs were 23.5 ± 12.5 s, 28.8 ± 6.1 s, and 40.2 ± 25.4 s, respectively. The CWEs have response times in the typical range of 20 sec or less observed for chromium ISEs in the literature [29-32, 34, 35]. The average response time for the nanoscale ISE was 22.7% and for the microscale ISE 71.1% greater than that of the CWE.…”

Developments in the Field of Conducting and Non-conducting Polymer Based Potentiometric Membrane Sensors for Ions Over the Past Decade

“…Nonetheless, the plasticizer selection is performed in line with its compatibility with the ionophore (solubility reasons) as well as the final ISE application. The names/abbreviations of the most common plasticizers employed in the ISE fabrication are as follows: benzyl acetate (BA) [ 88 ], bis-(1-butyl-pentyl)ad ipate (BBPA) [ 89 ], bis(2-ethylhexyl) adipate (DOA) [ 90 ], bis(2-ethylhexyl) phthalate (dioctyl phthalate, DOP) [ 91 ], bis(2-ethylhexyl) sebacate (BEHS) [ 92 ], bis( n -octyl)sebacate (DOS) [ 93 ], bibenzyl ether (DBE) [ 94 ], dibutyl phthalates (DBP) [ 95 ], dibutyl sebacate (DBS) [ 93 ], didecyl phthalate (DDP) [ 96 ], 2-nitrophenyl phenyl ether ( o -NPPE) [ 98 ], o -nitrophenyl octyl ether ( o -NPOE) [ 99 , 100 ] and tri- n -butyl phosphate (TBP) [ 101 ].…”

A comparative study of chromium(III) ion-selective electrodes based on N,N-bis(salicylidene)-o-phenylenediaminatechromium(III)

“…A number of ISEs based on PVC membrane [3][4][5][6][7][8][9][10][11][12][13][14][15][16], and coated wire electrodes [17][18][19] employing different neutral ionophores, have been made for determination of chromium ion. To our best knowledge, no carbon paste electrode for the detection of Cr ions has been reported to date.…”