Hey everyone, I'm just starting to try out a method for glutaraldehyde with DNPH. Does anyone have experience with this? I am following "Fast specific separation and sensitive quantification of bactericidal and sporicidal aldehydes etc...." from Elsevier Journal of Chromatography B, 692 (1996) 79-86.

Anyways, the standard prep they use is either worded incorrectly or something else. When I prepare a standard containing 1.25 g/L glutaraldehyde it precipitates a lot when adding the HCL in the sample prep:
5mL add 4 mL DNPH solutiong and 400uL 17% HCl and dilute to 10 ml with DI.