Protein precipitation and enzyme hydrolysis

Many HPLC analyses are carried out on biological samples such as blood, plasma, semm or urine. If urine analysis is to be carried out, the compound of interest is often excreted as the glucuronide or sulphate conjugate. These are very polar and are rarely determined directly. Samples are usually hydrolysed by acid, or an enzyme preparation to release the parent compound before analysis proceeds. 

plasma, serum or saliva are rarely determined directly by HPLC. Proteins and fats present in such samples are known to have a deleterious effect on HPLC columns. The minimum pretreatment for 

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