Chromium salts are widely used in industrial processes such as metal finishing and plating, as well as in the leather industry as a tanning agent, and in the manufacture of paints, dyes, explosives, and ceramics. Chromium may enter a water supply through the discharge of waste from these industries or from chromate-treated cooling waters, where it is frequently added for corrosion control. The hexavalent state of chromium, CrVI, is toxic to humans, animals, and aquatic life; it can produce lung tumors when inhaled and readily induces skin sensitization.
Hexavalent chromium in a sample can be measured using the diphenylcarbohydrazide method. 1,5-Diphenylcarbohydrazide is added to a sample under acidic conditions, which then reacts to give a purple color when hexavalent chromium is present. The color of the sample is proportional to the hexavalent chromium concentration in the sample.
Hanna Instruments offers a variety of technologies to measure chromium including spectrophotometers, photometers, colorimeters and Chemical Test kits (CTK).
Below are the most common products used for chromium measurement.
Spectrophotometers are available that have chromium methods in several ranges pre-programmed into the meter. The spectrophotometer offers the highest precision due to the quality of the optical system that has a wavelength accuracy of +/- 1.5 nm. The spectrophotometer allows for custom methods to be developed.
Benchtop photometers include multiparameter versions for water treatment, wastewater treatment, aquaculture, environmental and pools & spas. Each photometer is customized to have the parameters used by a specific industry. All benchtop have a digital pH electrode input allowing it to be used as a traditional pH meter.
Single parameter portable photometers are available in two ranges. The portable photometers have a CAL Check feature that allows for performance verification and if needed, recalibration using the CAL Check standards. The portable meters are available as a meter only or as a kit. The kit version include a rugged carrying case and CAL Check standards.
Checker HC, like a chemical test kit, are a reagent based design with a color change based on concentration. The handheld colorimeters, like portable and benchtop instrumentation, use the Beer-Lambert principle to determine the color change. The color change is measured by a photoelectric cell which is more accurate than subjective visual interpretation.
Reagents include the reagents used with chemical test kits and photometers.
Solutions for chromium measurement include ISE standards and ISA for calibration and measurement. Other solutions include the CAL Check standards for verifying and, if needed, the calibration of our portable photometers. Each CAL Check standard is supplied with a Certificate of Analysis stating the accuracy and traceability of the standard.
Accessories include spare cuvettes and caps for photometers, and magnetic stirrers to ensure adequate mixing when using an ISE.