Rapid determination of cholesterol in milk containing emulsified foods

In this study, a rapid and easy sample preparation method that involved no-heating saponification and dSPE (dispersive solid phase extraction) clean-up was developed to determine the level of cholesterol in milk containing emulsified foods (infant formula, baby food, cheese). The developed method utilised high performance liquid chromatography with an ultraviolet detector (HPLC-UVD) as a separation instrument. The optimum extraction conditions were determined as 10 mL isopropyl alcohol with 8.0 g (NH4)2SO4 per 1 g sample, and saponification was achieved using 25 mg KOH, 1.6 g NaCl and 100 mg of a silica based NH2. Cholesterol levels determined using CRMs (NIST SRM 1849 and 1544) were in the range of the certificated value and the recovery test using spiked materials ranged from 94.34% to 102.34% with a RSD of 0.63–4.10%. This method enables the accurate determination of cholesterol with reduced sample preparation time.