Caprolactam for industrial use — Determination of colour of 50 % aqueous caprolactam solution, expressed in Hazen units (platinum-cobalt scale) — Spectrometric method

The absorbance of a 50 % aqueous caprolactam solution is spectrometrically measured at a wavelength of 390 nm and an optical path length of 50 mm. The result is expressed in Hazen units by multiplying the absorbance measured by a constant factor equal to 150. This factor is derived from measurements of absorbance of diluted standard solutions of platinum-cobalt scale.