This improved sample preparation method allows for the quantitative measurement of over 60 drugs of different classes in urine for clinical purposes. Drugs of abuse include naturally occurring, semi-synthetic and synthetic drugs. The use of hydrolysis in the analysis of natural and synthetic drugs in urine has become standard practice in toxicology labs. Many laboratories currently use solid phase extraction or solid liquid extraction techniques in the sample preparation of urine. This method quantitatively measures multiple drugs of different classes in urine for clinical purposes. This method is known as the CLUMM (Clinical Urine Mega Method) and run on the Sciex 4500 using the Phenomenex Phenyl-hexyl Kinetex analytical column. The samples are hydrolyzed, then prepared using a dilute and filter technique followed by LC/MS/MS analysis.