Potassium dichromate in perchloric acid is very suitable for checking the photometric accuracy of spectrophotometers. In the UV range, the Potassium dichromate spectrum has characteristic maxima at 257 nm and 350 nm and characteristic minima at 235 nm and 313 nm. The spectrum reaches a plateau at 430 nm, which is used to determine photometric accuracy in the visible range.

Hellma Analytics purchases the reference material for this filter directly from NIST (SRMR 935a “Potassium Dichromate”). The filter solutions are manufactured in strict compliance with NIST requirements and filled under controlled conditions. The cuvettes are then immediately fused to become airtight.