Thin-layer chromatography on silica gel and alumina sintered plate

Thin-layer chromatography on precoated adsorbents fixed with fused glass. VI

Abstract

In a previous paper we reported the preparation of a new plate for thin-layer chromatography (TLC), which was made from silica gel-fused glass powder mixtures. Throughout the previous work the homogeneous soda-lime glass was used as both binder and base plate purposes.
In the present paper, we reported the success in the welding of the silica gel or alumina for TLC use over several kinds of glass or metal base plate using several kinds of sintered glass as binder. As shown in Table I, these materials are very much different each other in their expansion coefficient (α).
Using these silica gel and alumina sintered plates, thin-layer chromatographic separation of the following test mixtures was performed: azo dyes (Indophenol, Sudan Red G and Butter Yellow for silica gel sintered plate, and azobenzene, Sudan Yellow and p-aminoazo-benzene for alumina sintered plate), estrogens (estriol, estradiol and estrone for silica gel sintered plate) and alkaloids (quinine, codeine, brucine and thebaine for alumina sintered plate). All these plates are heat-stable, and those with glass base plate acid-resistant and, moreover, can be repeatedly used by soaking the chromatograms into cleaning solutions such as chromic acid mixture or concentrated nitric acid. As shown in Table VII, the silica gel quartz sintered plate has, among others, a very superior reproducibility of separation.
The welding mechanism of these silica gel and alumina sintered plates was clarified by means of scanning electron microscopic method. Although the heterogeneous systems made from such a silica gel or alumina(α=5.4 and 8.0 × 10^-7 cm/cm/°C) as adsorbent, lead silicate or soda-lime powdered glass (α=95 and 92 × 10^-7 cm/cm/°C) as binder, and quartz or aluminum (α =5.5 and 207 × 10^-7 cm/cm/°C) as base plate are not expected to weld well each other, the welding among these three materials did occur. As shown in photo. 12 (surface view of the plate) and photo. 35 (cross sectional view of the plate) obtained by the scanning electron microscopic method, the adsorbents are fixed among the three dimensional space formed by the sintered powdered glass and the glass or metal base plates without loss of their original surface structures. Thus, the sintered powdered glass does play a role of binder fixing adsorbents on the surface of the glass or metal plates even when these three materials are heterogeneous and very much different each other in their physical properties.