When I was doing the Biochemistry section of my college course we "collected" urine by putting a 20 litre aspirator in the Gents toilet at the college. It was used for practicing techniques of "drug" metabolite extraction and preparatioon for yous in High Pressure Lisuid Chromatography, and in Gas-Liquid Chromatography, It gave "authentic" extraction and metabolic results, and carefully calibrated amounts of the "drugs to be tested for was added, this helped in both detecting very low concentrations and also in calibrating the accuracy of teh instruments . With these calibrations we could detect concentrations in the body of 1:1000 million easily and a lot less of somethings.