Development of a New Kinetic Spectrophotometric Method for the Determination of Chromium with an Optical Probe

Abstract

The aim of this work is the development, optimization, and validation of a new spectrophotometric kinetic method for the determination of dissolved chromium species in water samples with the use of the polymethine dye Astra Phloxine FF. The progress of the chemical reaction was simple, effective, and precisely monitored from the start of the reaction using an optical probe. The method is based on the impact of Cr(VI) concentration on the rate of decrease in the Astra Phloxine FF concentration. The experimental data were evaluated using four experimental data analysis methods, namely with the initial rate method, the average rate method, the fixed time method, and the absorption peak volume change method. Under the optimal reaction conditions, the best results were achieved using the method of the average rate constant for evaluating the experimental data. Using this data evaluation method for the determination of Cr(VI), the LoD was found to be 1.87 µg L–1 and RSD ( n = 6; 0.2 mg L–1 Cr) 3.59%. The presented work was used for the determination of chromium in model samples—CRM material and tap and waste water—and with the calibration line method and the standard additions method.

A new approach for sulfite determination by headspace liquid-phase microextraction with an optical probe

“…The use of the optical probe allows the step of transferring the extract to a cuvette to be eliminated and the analytical signal to be recorded continuously. 1,15 This simplies the handling of the microextraction phase and reduces the analysis time. This also greatly improves the reproducibility of method compared with other methods proposed in the literature.…”

“…In comparison with commonly conducted spectrophotometric measurements, there is no stage of transfer of the analyzed solution into a cuvette, which makes it possible to record the analytical signal online immediately after the start of the chemical reaction in the system under study. 1 Consequently, the optical probe is ideally suited to monitor kinetic processes. When using an optical probe, all stages of kinetic analysis are performed in the same reaction vial, including mixing, the chemical reaction and the measurement of light absorption, which greatly simplifies and improves the accuracy and reliability of the analytical procedure.…”