Evaluation of analytical reflection scanometry as an analytical tool

Abstract

This paper describes three different methodologies for the easy readout of a potassium bulk optode film using a flatbed scanner working in reflection mode to obtain quantitative information. The analysis of the digital image through the analysis of the colour of the test zone requires the optimization of the scanner variables and further statistical evaluation of the method. In this study we used two different optical scanners, one colour calibrated scanner and another without calibration. Different image analysis protocols were applied: (i) with the calibrated scanner at 48 bits resolution and 300 dots per inch (dpi) colour depth; (ii) at 48 bits and 75 dpi without applying the image procedure and (iii) with a non-calibrated scanner but in its best scanning conditions, available in the scanner set up, of 24 bits and 600 dpi. After optimizing the scanner, variables such as resolution and colour depth, the obtained application ranges, in M units, for the different measurement system used were (i) from 4.3 × 10⁻⁷ to 0.1; (ii) 2.8 × 10⁻⁷ to 0.1; and (iii) 9.8 × 10⁻⁷ to 0.1 with a precision between 0.8 and 2.5%, 1.0 and 2.1%, 2.2 and 2.8%, respectively. Then, the trueness of the proposed scanometric methods was checked by means of a statistical study and finally, the proposed method was validated against a reference procedure using water samples from different sources and beverages, showing that there are no significant statistical differences at a 95% confidence level.