Accuracy of [total As] determination in naturally arsenic contaminated water samples, cross-calibrated against atomic absorption spectroscopy (AAS) as the benchmark technique.

Goodness of fit (R²) values were calculated using the formula . Error bars indicate the uncertainty of each measurement. For the field test measurements, uncertainties were taken from the colour chart, whilst for electrochemical measurements, uncertainties were determined from the standard error in the slope and y-intercept of the linear regression obtained from the internal calibration made using the method of standard additions.