Diazotization of catecholamines and their analogs and metabolites for urinary screening tests: chemical aspects.
Coupling of diazotized p-nitroaniline to catecholamines and their metabolites in urine has been proposed for use in screening for secreting neuroblastoma in childhood. We have coupled diazotized p-nitroaniline to catecholamines, derivatives, and metabolites and examined the reaction products by thin-layer chromatography and physico-chemical methods (ultraviolet spectra, mass spectroscopy, nuclear magnetic resonance). We conclude that during diazotization, products containing a p-hydroxybenzyl alcohol or a p-hydroxybenzoic acid structure (e.g., vanillic acid, vanilmandelic acid, 3-methoxy-4-hydroxyphenyl-ethyleneglycol, metanephrine, normetanephrine, synephrine, and isoproterenol) react with a diazonium cation, with release of their alcohol or acid moiety. Therefore the mentioned qualitative screening methods are very nonspecific. In contrast, thin-layer chromatographic screening methods provide complete separation and unambiguous identification of those metabolites and are to be preferred for use in detecting secreting neuroblastoma in childhood.
Diazotization of catecholamines and their analogs and metabolites for urinary screening tests: chemical aspects. Coupling of diazotized p-nitroaniline to catecholamines and their metabolites in urine has been proposed for use in screening for secreting neuroblastoma in childhood. We have coupled diazotized p-nitroaniline to catecholamines, derivatives, and metabolites and examined the reaction products by thin-layer chromatography and physico-chemical methods (ultraviolet spectra, mass spectroscopy, nuclear magnetic resonance). We conclude that during diazotization, products containing a p-hydroxybenzyl alcohol or a p-hydroxybenzoic acid structure (e.g., vanillic acid, vanilmandelic acid, 3-methoxy-4-hydroxyphenyl-ethyleneglycol, metanephrine, normetanephrine, synephrine, and isoproterenol) react with a diazonium cation, with release of their alcohol or acid moiety. Therefore the mentioned qualitative screening methods are very nonspecific. In contrast, thin-layer chromatographic screening methods provide complete separation and unambiguous identification of those metabolites and are to be preferred for use in detecting secreting neuroblastoma in childhood.