Simultaneously calibrate and detect multiple analytes to offset the effects of co-existing regents and environmental fluctuations

Background

The real water bodies contain varieties of contaminants and varying with time and climate, for which a fast and accurate in-situ approaching for simultaneously detecting multiple pollutants would be urgently on demand. Although the differential pulse voltammetry (DPV) gives a promising approach for simultaneous detection of multiple pollutants due to the high-resolution characteristic oxidation-reduction peak of target pollutants, it is very sensitive to the unpredictable environmental fluctuations, which should be addressed through specific anti-interference techniques based on synchronously achieved data.

Results

A multi-pollutants simultaneous calibration and detection (MSCD) strategy and corresponding electrochemical sensors were proposed. Combined with the characteristic scanning potentials of analytes, a series of diluted or analyte-added water samples were detected, and a linear regression algorithm is developed to reduce the errors caused by interfering substances, unpredictable environmental fluctuations. Applied in the detection of 40–100 μM nitrite (NO₂⁻) and 100–400 μM sulfite (SO₃²⁻), MSCD strategy has exhibited acceptable anti-interference to pH, temperature fluctuations and high concentration of interfering substances. In addition, the relative errors of multiple repeat measurements of nitrite and sulfite do not exceed 8.2 % and −8.3 %, respectively. When using different MSCD sensors, the relative errors were less than −11.6 % and 3.9 %, due to offsetting the deviation of fabrication batches. In the detection of actual water samples, the relative error is less than ±7.8 %, and proved to be significantly more accurate than commonly used electrochemical methods.

Significance

Compared with commonly used laboratory calibration methods, the proposed MSCD strategy exhibits excellent anti-interference performance in co-pollutant matrices with pH fluctuations and temperature changes. This MSCD strategy is expected to adapt to various electrochemical targets with appropriate sensing materials and provide an alternative option for simultaneously detecting multiple pollutants with high accuracy and repeatability.