A large scale method was reported in preceeding paper {(1)
J. Chromatogr., 178, 63 (1979)} for the preparation of high quality diatomaceous earth for gas chromatography. However, differently from the previous small scale case {(2)
Bunseki Kagaku, 28, 579 (1979)} the deactivated Celite of first rank could not be obtained sometimes by this method. Therefore, effects of various drying conditions of pretreated wet diatomaceous earth and its storage days prior to silylation which are designated by IV were examined. I: The sample was laid in thin layer on a plate, airdried for about 2 h and stored. II: The sample was rinsed with methanol, air-dried quickly, and stored. III: The sample was stored in a polyethylene vessel without use of any drying procedure, and air-dried immediately before the silylation at each time. IV: The sample was heat-dried at 220 °C or so in a thick layer (4 cm in thickness) for about 1.5 h and stored. V: The sample was dried in a gas oven with air circulation at 110 °C for about 1 h, and stored. After storage of various lengthes, the silylation was carried out in a way described in the previous paper {(3)
ibid., 28, 307 (1979)}. The characterization of properties of the silylated supports were made with TCD gas chromatograph packed a 0.5 m×3 mm packed column with these supports as presented in the previous paper (3). The quality of the supports was graded as A, B and C in the descending order. We report in the present paper the following finding which is an important notice to apply the proposed method {(1), (2)}. The drying process must be carried out at room temperature as quickly as possible after the hydrolysis of the raw material diatomaceous earth and followed by the silylation in no time. The longer the storage time of the hydrolyzed and dried material, the lower the quality of the products.
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