COLORIMETRIC STRIP TESTS - A COMPARISON OF VISUAL AND REFLECTOMETRIC MEASUREMENTS FOR QUANTITATIVE APPLICATIONS

The use of indicator-based colorimetric strip tests for measuring chro mate and nitrate in spiked and waste water samples was validated. Test strip readings made by reflectometry were significantly more accurate and reproducible than those made by a visual comparisons to a referen ce color chart. Each of the analytes was consistently detected at 1 to 2 mu g/ml, using the reflectometer. There was an excellent correlatio n between the analytical results obtained with the strip tests and tho se obtained using the more traditional laboratory methods of inductive ly coupled plasma/mass spectrometry and ion chromatography. This study shows that the use of strip tests for field screening, and as a presc reen in the laboratory, can be a time- and cost-effective alternative or adjunct to currently used laboratory methods.