A Novel Potentiometric Sensor for Thiocyanate Based on an Amide‐Linked Manganese Diporphyrin Xanthene

Abstract

The synthesis of a new compound, amide-linked manganese diporphyrin xanthene (Mn 2 Cl 2 ADPX), and its application for preparation of thiocyanate selective electrodes was described. The electrode was prepared with a PVC membrane combining Mn 2 Cl 2 ADPX as an electro active material, 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer in the percentage ratio of 3 : 65 : 32 (Mn 2 Cl 2 ADPX: o-NPOE: PVC, w : w : w). The electrode exhibited linear response within the concentration range of 2.4 Â 10 À6 to 1.0 Â 10 À1 M SCN À , with a working pH range from 3.0 to 8.0 and a fast response time of less than 60 s. Several electroactive materials and solvent mediators have been compared and the experimental conditions were optimized. The Mn 2 Cl 2 ADPX based electrode shows obviously better response characteristics than that of monoporphyrin manganese in terms of working concentration range and slope. Selectivity coefficients for SCN À relative to a number of interfering ions were investigated. The electrode exhibits antiHofmeister selectivity toward SCN À with respect to common coexisting anions. The electrode was applied to the determination of SCN À in body urine with satisfactory results.

The Analysis of Cyanide and its Breakdown Products in Biological Samples

“…Thiocyanate, due to its lipophilicity, is well-suited for ISE analysis and has been successfully analyzed by ISEs (23). ISEs have been developed that exhibit good agreement with ion chromatography (194) and spectrophotometry (186)(187)(188)(189), and have been used to analyze thiocyanate from plasma (194), urine (64,65,68,69,73,79,80,184,(186)(187)(188)(189)243), and saliva (64,66,68,69,73,79,80,182,183,(186)(187)(188). For example, ISEs based on crystal violet or methylene blue and a selective polymeric membrane containing a nickel(II)-azamacrocycle complex showed excellent selectivity and sensitivity and were successfully used for the analysis of thiocyanate in urine and saliva (187,194).…”

“…One of the most common methods for analysis of cyanide, thiocyanate, and more recently ATCA is gas chromatography. Common detectors used for analysis of cyanide or its metabolites are the electron capture detector (ECD) (95,103,119,125,128,200,205,211,212,241,246), nitrogen-phosphorus detector (NPD) (45,53,65,105,113,114,117,121,126,131,135,137,152,202,(207)(208)(209), and MS detector (61,91,107,108,111,117,199,210). Although most of these methods are used for detection of cyanide in blood, some groups have applied GC techniques for other biological matrices and for the detection of thiocyanate and ATCA.…”

Opportunities and challenges of using ion-selective electrodes in environmental monitoring and wearable sensors

“…Considering that the majority of sensors for heavy-metals rely on anodic stripping voltammetry based on mercury films, the WFD legislation dictates a shift from mercury to other type of films or to new analytical techniques [3]. Finally, the detection of other harmful ions in the environment, e.g., thiocyanate, azide, not at trace level remains important and ISEs can also aim at this market [17][18][19].…”