It has been found that many racemic aromatic amino-acids can be resolved into their optical enantiomorphs on paper chromatograms. Sufficient cases have been examined to enable a preliminary formulation to be made of the structural features necessary for resolution to occur. THE optical resolution of amino-acids on paper chromatograms was first reported in 1951 by Kotake, Sakan, Nakamura, and Senoh ( J . Amer. Chem. SOC., 1951, 73, 2973). In a recent paper (Dalgliesh, J., 1942, 137) it was shown that DL-kynurenhe (I; R = NH,, R' = H) is resolved into its optical enantiomorphs, a result confirmed by Mason and Berg (J. RioZ. Chem., 1952, 195, 515). Similar resolution has also been found to occur with 3-hydroxy-~~-kynurenine (I; R = NH,, R' = OH) (Dalgliesh, Biochem. J., 1952, 52, 3). /\ CO*CH,*yH.CO,H R\cH,-~H.co,H R'/),CH,-yH*CO,H b)oH NH, HOI\/R NH, OHWhile investigating aspects of tyrosine metabolism the resolution of 2 : 5-dihydroxyphenyl-DL-alanine was observed, and other related amino-acids have therefore been investigated.Resolution has also been found with 2 : 3-dihydroxyphenyl-~~-alanine (11) and 3 : 4-dihydroxy-2-methylphenyl-DL-alanine (I11 ; R = Me, R' = H), whereas none occurred with 3 : 4-dihydroxyphenyl-DL-alanine (111 ; R = R' = H) or its 5-methyl derivative (I11 ; R = H, R' = Me). Resolution was shown by the appearance of two spots on the chromatogram of a chemically pure racemate, these being of equal size, shade, and intensity by whatever means they were revealed. Where optical isomers were available, these gave only a single spot which corresponded to one of the spots given by the racemate : thus, both D-and L-isomers of 2 : 5-dihydroxyphenylalanine (Neuberger, Biochem. J., 1948, 43, 599) gave spots corresponding to the two spots given by the racemate, and the ratio of the Ri g values of the authentic D-and L-compounds was the same as that for the two spots given by the racemate. ) R NH, R'

Joint Working Groups of the European Brewery Convention, the American Society of Brewing Chemists, and the Master Brewer's Association of the Americas have developed a system of flavour terminology to meet the dual needs of (i) enabling brewers to communicate effectively about flavour and (ii) naming and defining each separately identifiable flavour note in beer. The system comprises 44 terms to meet the first objective while 78 additional terms are suggested for the second. The Industry is urged to use this terminology and comment on it.

1. A gas-liquid-chromatographic procedure is described which permits separation and identification on the same chromatogram of a wide range of substances occurring in urine or tissue extracts. The method uses hydrogen flame ionization, which detects organic compounds whether free or conjugated with no requirement for specific reactive groups. 2. For chromatography, carboxyl groups are quantitatively converted into methyl esters or trimethylsilyl esters. Phenolic, alcoholic and potential enolic groups are converted into trimethylsilyl ethers. Separations are carried out on a 6ft. column of either 10% F-60 (a polysiloxane) or 1% F-60, temperature programming at 2 degrees /min. being used over such part of the temperature range 30 degrees -260 degrees as is required. Propionyl derivatives of hydroxy compounds can also be used, but only on a non-quantitative basis. Derivatives and columns have been selected for optimum range of usefulness when large numbers of samples are examined by using automated gas chromatography. 3. The method is applicable to: fatty acids above butyric acid; di- and tri-carboxylic acids; hydroxy acids and keto acids; polyhydroxy and alicyclic compounds such as glycerol, inositol, quinic acid, shikimic acid, ascorbic acid and sugar alcohols; aromatic hydroxy and acidic compounds, both benzenoid and indolic; sesquiterpenes; steroids; glycine conjugates; mercapturic acids; glucuronides. It is not satisfactory for sulphate conjugates, iminazoles or polypeptides. 4. Methylene units provide an accurate and reproducible parameter for characterizing peak position. Methylene unit values are reported for a large variety of substances occurring in, or related to those occurring in, urine and tissue extracts. 5. The nature of derivatives was confirmed by combining gas chromatography with mass spectrometry. Combined gas chromatography-mass spectrometry gives a diagnostic tool of great power in the evaluation of metabolic patterns, and various uses are discussed.

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