Volume 99, No. 1179, Pages 313-384 June, 1974THE ANALYSTTHE JOURNAL OF THE SOCIETY FOR ANALYTICAL CHEMISTRYCONTENTSPageORIGINAL PAPERSA Direct Gas-chromatographic Method for the Determination o f BasicNitrogenous Drugs in Pharmaceutical Preparations-N. D. Greenwoodand I. W. Guppy . . . . . . . . . . . . . . . .A Method for the Determination o f Volatile Fatty Acids in the BloodPlasma o f Ruminant Animals-J. W. Gardner and G. E. Thompson . .Quantitative Determination o f the Enantiomeric Purity of SyntheticPyrethroids. Part II. S-Bioallethrin-F, E. Rickett and P. B. Henry . .The Detection and Determination o f Polynuclear Aromatic Hydrocarbonsby Luminescence Spectrometry Utilising the Shpol'skii Effect at 77 K-G. F. Kirkbright and C. G. de Lima .. . . .. . . . . . .Application o f the Spectrophotometric Determination of Nickel andCobalt in Mixtures With Bipyridylglyoxal Dithiosamicarbazone t o theAnalysis o f Catalysts-J. L. Baharnonde, D. PBrez Bendito and F. Pino . .Ionic Polymerisation as a Means o f End-point Indication in Non-aqueousThermometric Titrimetry. Part VI. The Determination o f Thiols-E. J. Greenhow and Miss L. H. Loo . . a . . . . . . . . .Determination o f Ammonia Levels in Water and Wastewater With anAmmonia Probe-W. H. Evans and 6. F. Partridge . . .. . .The Coulometric Determination o f Trace Levels of Sulphur in GalliumPhosphide-K. Gijsbers, L. Bastings and R. van de LeestBook Reviews . . .. . . . . .. . . . . . . . .Erratum . . . .. . . .- . . . . . . . . . . . . . . .. .353326330338356360367376381384Summaries o f Papers in this Issue ' . . . vi, vii, xii, xivPrinted for the Society for Analytical Chemistry by Heffers Printers Ltd., Cambridge, EnglandAll communicationsto beaddressedtothe Managing Editor,TheAnalyst, 9/10Savile Row, London, W l X l AFEnquiries about advertisements should bs addressed to J. Arthur Cook, 9 Lloyd Square, London, WC1X 9BAEntered as Second Class at New York, U.S.A., Post Offic