Determination of pararosaniline hydrochloride in workplace air

Pararosaniline hydrochloride (CPR) is a dye used for colouring paper, leather and natural and artificial fibres. It is also used in analytical and microbiological laboratories. It is a carcinogenic substance of category 1B. In analytical chemistry, it is used for detecting the following among others: bromates, formaldehyde, ozone, sulphite and sulfur dioxide. CPR is a dye commonly used in microbiology for staining preparations, for staining bacteria, antibodies or other organisms. In Poland, about 800 employees were exposed to this substance. The lack of methods for the determination of pararosaniline hydrochloride in workplace air makes it impossible to assess the occupational exposure of workers to this substance. For this reason, a determination method has been developed, which allows for the determination of pararosaniline hydrochloride in the air. This method makes it possible to determine the concentration of CPR in the air at the workplace within the range from 0.002 to 0.04 mg/m³ (for an air sample of 120 L). The method is based on the adsorption of pararosaniline hydrochloride present in the workplace air on a polypropylene filter, eluting the substance deposited on the filter with methanol and analysing the solution thus obtained using high-performance liquid chromatography with a diode array detector (wavelength of 544 nm). Using an Ultra C18 (250 mm length) chromatographic column at a temperature of 23 °C and the mobile phase of methanol:0.1% phosphoric acid(V) (95:5, v/v) at flow rate of 0.6 mL/min makes it possible to determine the content of pararosaniline hydrochloride in the presence of aniline, nitrobenzene and 4-tolylamine. Limit of detection and limit of quantification were 0.17 ng/mL and 0.51 ng/mL, respectively.