Michael A. Madson

Analysis of amino acids as their tert.-butyldimethylsilyl derivatives by gas-liquid chromatography and mass spectrometry

A gas-liquid chromatographic procedure is described which will separate and quantitate the seventeen amino acids typically found in protein acid hydrolyzates. If present, tryptophan, cysteine and carboxymethylcysteine can also be simultaneously assayed via this method. The amino acids, as their tert.-butyldimethylsilylated derivatives, are readily separable on SE-30 (wall-coated open-tubular) and OV-17 (bonded) capillary columns, as well as on packed gas-liquid chromatographic columns coated with the same liquid phases. Retention times and responses for all amino acids and internal standards are given. Mass spectral analysis of all tert.-butyldimethylsilylated amino acids is presented and displays a characteristic and unique [M- 57] fragment ion for each amino acid which often dominates the mass spectrum. Application of this method is demonstrated using four well characterized proteins.

An improved preparation of 3-deoxy-d-erythro-hexos-2-ulose via the bis(benzoylhydrazone) and some related constitutional studies☆

Abstract Sugar osazones and glycosuloses rapidly and quantitatively react with hydroxylamine to produce oximes that give trimethylsilyl derivatives suitable for g.l.c. and mass spectral analysis. The reaction of d -glucose with benzoylhydrazine to give the bishydrazone of 3-deoxy- d - erythro -hexos-2-ulose ( 1 ) [H. El Khadem et al., Carbohydr. Res. , 22 (1973) 381-89] was re-investigated, together with the conversion of this compound to the hexosulose. Although by-products are produced in the reaction, including the bis(benzoylhydrazone) (osazone) of d -glucose, the major product is the monohydrate of the bis(benzoylhydrazone) of 1 (colorless). The anhydrous (yellow) form can be prepared from the monohydrate by crystallization from absolute ethanol and has quite different physical properties. Improvements of the original preparation are described that allow the preparation of the bishydrazone and its subsequent conversion to 1 via transhydrazonation in 44% overall yield, and with no detectable contamination by d -glucose or d -glucosone. Evidence is presented that the previously reported cyclic form of the bis(benzoylhydrazone) of d -glucose is the bis(benzoylhydrazone) (monohydrate) of 1 .

Gas-liquid chromatography and mass spectral analysis of mono-, di- and tricarboxylates as their tert.-butyldimethylsilyl derivatives

A gas-liquid chromatographic (GLC) procedure is described which permits the baseline separation and quantitation of twenty saturated monocarboxylates, sixteen dicarboxylates (both alkanedioic and alkenedioic), and the tricarboxylates citrate and aconitate in a single GLC analysis. The carboxylic acids, as their tert.-butyldimethylsilylated derivatives, are readily separable on a SPB-1 (bonded) capillary column. Separation data on an OV-17 (bonded) capillary column and a SP-2250 packed column of these carboxylates, in addition to fifteen unsaturated carboxylates, are also given. The tert.-butyldimethylsilylation of carboxylic acids in their free or ammonium salt forms is accomplished in a single derivatization step with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide. Retention data and responses for all mono-, di- and tricarboxylic acids are given. Mass spectral analysis of all tert.-butyldimethylsilylated carboxylic acids is presented and each displays a prominent and characteristic [M-57] fragment ion.

Gas-liquid chromatography and mass-spectral analysis of per-O-trimethylsilyl acyclic ketoxime derivatives of neuraminic acid

Abstract The per- O -trimethylsilyl derivatives of the acyclic O -methyl- and O -(trimethylsilyl)ketoximes of both the methyl and ethyl esters of N -acetylneuraminic acid and N -glycolylneuraminic acid, and also the acyclic O -benzylketoximes of the methyl esters of these N -acylneuraminic acids were synthesized. In addition, the per- O -trimethylsilyl derivatives of the acyclic O -trimethylsilylketoximes and the O -trimethylsilyl( 15 N)ketoximes of the trideuteriomethyl esters of N -acetyl- and N -glycolylneuraminic acid were prepared. For comparison, the per- O -trimethylsilyl derivatives of the cyclic ethyl esters of the two N -acylneuraminic acids were synthesized and all compounds were studied by gas-liquid chromatography and combined gas-liquid chromatography-mass spectrometry.