I am working on analysis of drugs/metabolites in human urine. Blank plasma is frozed first and then thawed. After thawing, I see quite a lot of precipitate. I suspect it is proteins. However, coworkers told me that there are almost no proteins present in healthy human urine. What is the precipitate? Does anyone have a table listing major components in urine?

Thanks for your input!

If a patient is catabolic you may have gobs of proteins in the urine. More likely you have precipitation from small molecules, though. The Ciba-Geigy tables, and similar ones, donīt help much as they show general figures for healthy persons. Some clinical chemistry books can give you some idea on substances used in assessment of illness. To find out of what urine is composed would be a lifeīs job (and byond).
Donīt worry much about precipitates, make sure you get high recovery of your analytes.