Automated sample preparation for cholesterol determination in foods.

An automated sample preparation system has been developed for the determination of cholesterol in a wide range of matrices. Isolation of cholesterol is performed with a robotic arm coupled with a series of modular stations. Samples are introduced into the system which adds the appropriate reagents, carries out the saponification, pH adjustment, solid-phase extraction and drying steps. This system was evaluated using 15 different food matrices. The average recovery for NIST standards exceeded 97%. A solution of n-hexane-2-propanol was substituted for the traditional methanol-chloroform extraction. Manual pH adjustment was replaced with a buffer. Manual and automated methods were compared and no difference was observed at the 95% confidence level.