PHOSPHATE COLORIMETRIC ANALYSIS USING A DESKTOP SCANNER AND AUTOMATED DIGITAL IMAGE ANALYSIS: A DIDATICAL EXAMPLE TO TEACH COLORIMETRIC ANALYSES

We propose here the quantification of the phosphorus content in cola drinks by molybdenum blue method. Molybdenum blue method was carried out in the wells of a microplate, where method miniaturization represents reduction in reagents required, improved safety, reduced waste stream, and increased sample throughput. The phosphate concentration was determinate using scanned images of the microplate. Extraction of RGB values was carried out using ImageJ, the pugling Readplate was used allowing extraction of RGB values of all wells simultaneously. A Microsoft Excel spreadsheet is afforded in Google Drive, it organize data taken from ImageJ to afford calibrations curves and phosphate concentration in cola drinks. Calibration curves were prepared at 500-2500 mu g L-1 of P with good linearity (R > 0.95). Phosphate concentrations in cola drinks determinate using digital images method are statistically equivalent to concentrations determined using a spectroscopic method at a 95% confidence interval.