Reference

Derivatization of trichothecenes and water treatment of their trimethylsilyl ethers in an anhydrous apolar solvent

Derivatization of trichothecenes and water treatment of their trimethylsilyl ethers in an anhydrous apolar solvent. Rizzo, A. F.; Saari, L.; Lindfors, E. (Natl. Vet. Inst., Helsinki 00101, Finland). J. Chromatogr., 368(2), 381-6 (English) 1986. CODEN: JOCRAM. ISSN: 0021-9673. DOCUMENT TYPE: Journal CA Section: 4 (Toxicology) One of the most common methods of derivatization is silylation, which transforms trichothecenes into trimethylsilyl ethers (TMSEs). In this study, the silylating agents were trimethylsilylimidazole (TSIM) [18156-74-6] (reagent I) and a mixt. of TSTM, trimethylchlorosilane [75-77-4], and EtOAc (1:0.2:9) (reagent II) freshly prepd. each day. The aim was to improve the detectability of 6 trichothecenes [4-deoxynivalenol (DON) [51481-10-8], diacetoxyscirpenol (DAS) [2270-40-8], fusarenon X (F-X) [23255-69-8]t, nivalenol (NV) [23282-20-4], F 2 toxin (I) [17924-92-4], and HT 2 toxin [26934-87-2]] by performing selective hydrolysis of the reagent, after silylation, to eliminate its interfering effect on the products of derivatization during gas chromatog. Gas chromatog. anal. of the samples was performed on a Varian gas chromatograph equipped with electron-capture detection (63Ni foil) and a fused silica column (25 m ′ 0.32 mm internal drain.) coated with a 0.2 mm Noribond OV-1 bonded phase. A remarkable difference was obsd. in the intensity of the peaks of DON, DAS, F-X, and NV when injected in the presence of the reagent when the latter had been hydrolyzed and removed with water. Only in the cases of I and HT 2 toxin was the amt. of TMSEs practically the same. When a polar solvent such as EtOAc was added to the reacted sample and no water treatment was performed, I and HT 2 toxin were the only trichothecenes detected, although in smaller amts. than in the case of samples dild. in hexane. Thus, in the case of trichothecenes, after the silylation has been performed, the reagent should be removed. This is also supported by the fact that, after the reaction, moderate diln. of the sample using an apolar solvent (hexane) gives a better result than undiluted sample or if the sample is dild. in the reagent itself. In other words, after the trichothecenes have been converted into TMSEs, the smaller the amt. of reagent injected together with the sample the better is the end result.

Preparation of trimethylsilyl derivatives of thiamphenicol

Preparation of trimethylsilyl derivatives of thiamphenicol. Janssen, G.; Vanderhaeghe, H. (Rega Inst. Pharm. Inst., Univ. Leuven, Louvain, Belg.). J. Chromatogr., 134(2), 365-74 (English) 1977. CODEN: JOCRAM. DOCUMENT TYPE: Journal CA Section: 64 (Pharmaceutical Analysis) The silylation of thiamphenicol (I) [15318-45-3] was investigated. Treatment of I with hexamethyldisilazane [999-97-3] or N-trimethylsilylimidazole [18156-74-6], either alone or in the presence of trimethylchlorosilane [75-77-4], in MeCN or pyridine yields the bis(trimethylsilyl) ether deriv. [63088-89-1]. These procedures, however, cause to some extent the formation of 1-(p-methylsulfonylphenyl)-2-monochloroacetamido-1,3-propanediol. Silylation with N,O-bis(trimethylsilyl)acetamide [10416-59-8] gives, depending on the solvent used, the mono-, bis- and tris-trimethyl derivs.