A wide choice of tests is available for routine analysis in different applications. Depending on the optical system and the wavelength employed, photometer and test set make up a matched system with different specific advantages.
For use with portable photometers, test sets need to be straightforward. The low consumption LED optics allows the use of easy-to-use and cost-effective test sets, e.g. powder tests. In the laboratory, instruments with barcode and utmost optical sensitivity suggest the use of high-precision tests with barcode reader, certificate and quality assurance support.
WTW continues to expand the reagent offering. Not only are new tests developed, but the compatability of tests with different instruments is continuously being developed. Due to the different photometer optics, one test may yield different measuring ranges in different instruments; LED photometers may have smaller measuring ranges for the same test.

In reviewing lot certificates, one recognizes the most important factor: Choosing the matching measuring range is critical. Every concentration determination is accurate only within the linear absorption range.
At the limits of the measuring range, the given tolerance has the biggest impact on the results. Therefore, it may be worth repeating the measurement using a test set with a better suited measuring range.