Three methods for the determination of 2% w/v glutaraldehyde solution were compared: the titration of acid produced from the reaction of glutaraldehyde with hydroxylamine; an ultra-violet spectrophotometric difference method which depends on the formation of a transient absorbing species on the reaction of glutaraldehyde with hydroxylamine; derivatization with 2,4-dinitrophenylhydrazine followed by high-performance liquid chromatography (HPLC). The methods were applied to the determination of glutaraldehyde in the disinfectant reservoir of an Olympus EW10 automatic endoscope washer/disinfector during serial processing of endoscopes. Twenty endoscopes could be processed before the solution needed changing. The spectrophotometric difference and HPLC methods gave equivalent results. The titrimetric method gave higher results but would be suitable in this case since relative concentrations were required to be determined. Activated 2% w/v glutaraldehyde solution was stored at room temperature for up to 181 days. At this time the titrimetric method gave a value of 1.70% w/v and the HPLC method one of 1.34% w/v. The spectrophotometric difference method gave a value of 0.93% w/v and should be used where a stability-indicating method is required.
- endoscope washer/disinfector
- ultra-violet spectrophotometric difference