Activation and standardization of purified silica gel for column chromatographic cleanup of pesticide residue extracts.

Activation and standardization studies have been conducted with high purity grades 950 and 923 silica gel to obtain an effective adsorbent for cleanup of pesticide residue extracts. Activation of silica gel at 130°C or 300°C for a 2-hr period was very satisfactory for separating pesticides from biological materials with high recovery of pesticides. No gain in the activity of the adsorbent resulted from prolonging heat treatment beyond the 2-hr period. It was also found that the activity of the silica gel was not affected by storing it in an air-tight container for as long as 60 days.