Ultrasonic-assisted precolumn derivatization-HPLC determination of acrylamide formed in Radix Asparagi during heating...

An ultrasonic-assisted precolumn derivatization-HPLC method was established and validated for the determination of acrylamide formed in traditional Chinese herb Radix Asparagi during heating process. This method entails extraction with water, ultrasonic-assisted derivatization with 2-mercaptobenzoic acid. The final extracted acrylamide derivative was separated on C(18) column by using a mixture of acetonitrile and acetic acid (1 gL(-1) water solution) (20:80, v/v) as mobile phase. The flow rate was 0.7 mL min(-1) and the detection wavelength was set at 238 nm. Factors influencing the derivative reaction were evaluated and the optimum derivatization conditions were as follows: molar ratio of derivative reagent to acrylamide was 35:1, pH 8-12, ultrasonic-assisted reaction time was 100 min. The calibration curve of acrylamide showed good linearity in the range of 0.015-4.5 microg mL(-1) with correlation coefficient of 0.9999. The limit of detection was estimated to be 25 microg kg(-1) based on the signal-to-noise ratio of 3 recorded at 238 nm. Recovery of acrylamide from the sample was 106.6+/-6.6%. Relative standard deviation of five duplicate determinations for the same sample solution was 1.59%.