Significant Reduction of Analysis Time with Bulk Sensors Operating in Nonequilibrium Mode.

The concept of reducing the analysis time with the bulk sensors operating in nonequilibrium mode is formulated theoretically and verified experimentally with ion-selective polymeric optodes. The influence of the measurement time on the optical response range, span, median, and sensitivity is calculated and demonstrated experimentally. Model aqueous samples are successfully analyzed using a nonequilibrium measurement protocol with conventional sodium-selective optodes and with pH optodes containing lipophilic organic electrolyte. The analysis time is significantly reduced from 300 to ca. 100 s, with sufficient recovery, reproducibility, and precision of the sample determination.