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Quantitative Determination of NTA and Other Chelating Agents in Detergents by Potentiometric Titration with Copper Ion Selective Electrode

“…S7, Supporting Information). 6 In contrast to these chelating agents shown in Fig. 3, bis(2-hydroxyethyl)glycine, also known as bicine or DHEG, was not quantified by this method, presumably explained by its lower stability constant toward Cu 2+ ion compared to the compounds in Fig.…”

“…Then the electrode potential abruptly increased with a point of inflection, which means the equivalence point of the titration. 6 After that, the addition of excess Cu 2+ resulted in an almost steady decrease in electrode potential reading, which may be caused by dilution.…”

“…This is another notable point in comparison with the fact that tripolyphosphate acts as an inhibitor for the Cu 2+ /CAS system 4 and for the potentiometric titration system using Fe(III) in the presence of ferroin. 6 These results suggest that neutralization is also recommended especially for unknown samples with high pH value for appropriate titration.…”

“…There has also been a somewhat related example of a titration method by use of a copper ion selective electrode commercially available, which mainly focused on a fractional titration between Cu 2+ and Zn 2+ with 3,6-dioxaoctane-1,8-diaminetetraacetate (EGTA) as a titrant. 6 Another potentiometric titration method of using iron(III) chloride in the presence of ferroin with a purpose-made electrode under an acidic condition (pH 4.7) has also been reported, where quantitative determination of EDTA and NTA in a detergent formulation was carried out. 7 In this case, the successful fractional titration of EDTA and NTA is favorable for the determination of chelating agents in detergent formulations.…”