Fig. 2
From: Method development for 14C-labeling of IgG antibodies in preparation for clinical trials
Determination of formaldehyde concentration using chromotropic acid. a Hypothetical reaction products of the chromotropic acid reacted with formaldehyde in strongly acidic media. The monocationic dibenzoxanthylium is the more probable product, although the chemistry is intricate and not yet fully understood. b calibration curve using standard solution. c Example images depicting reactions with standard solutions