iV SUMMARIES OF PAPERS IN THIS ISSUESum ma ries of Papers in thisJane, 1979IssueRelevance of the Approximately Hyperbolic Relationship BetweenFluorescence and Concentration to the Determination ofQuantum EfficienciesAn absorptivity-related constant and a quantum efficiency-related constantcan be derived, by a simple graphical procedure, from data obtained in astandard fluorimeter. The quantum efficiency of an unknown fluorophorecan be determined by comparison of its quantum efficiency-related constantwith that of a fluorophore of known quantum efficiency. The absorptivitycan similarly be determined using the absorptivity-related constant. Thismethod relies on the approximately hyperbolic relationship that existsbetween light absorbed and chromophsre concentration.The approximationmay be derived from the Beer - Lambert equation and the limits of its validityhave been tested using theoretical and1 experimental data.Keywords ; Beer - Lambert equation ; fluoyescewe eficiemiesNIGEL GAINSDepartment of Biology, University of York, York, YO1 5DD.and ALAN P. DAWSONSchool of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ.Anaiyst, 1979, 104, 481-490.Determination of Cadmium .in Blood and Urine by FlameAtomic-fluorescence SpectrometryThe development is described of an atomic-fluorescence method for thedetermination of cadmium in blood and urine. The method involves onlythe direct aspiration of acidified urine or diluted and acidified blood into theflame. Calibration is achieved simply by using acidified aqueous standardsand by the application of a pre-determined correction factor to account forchanges in the uptake rate. The sensitivity, accuracy and precision arecomparable to those given by most techniques that are currently in use €orthe determination of cadmium in biological materials.The simplicity ofthe method permits rapid analyses of large numbers of samples (more than25 samples per hour) and is particularly useful for the survey of populationsof people exposed to cadmium. The instrumentation used employs a two-source background correction system. This is essential for maximumaccuracy and allows automatic correction for the scatter, which is the primarycause of inaccuracies in the atomic-fluorescence spectrometric determinationof cadmium.Keywovds ; Flame atowtic-fluwescence spectrometvy ; cadmium determination ;blood analysis ; wine analysisR.G. MICHEL, M. L. HALL and 6. M, OTTAWAYDepartment of Pure and Applied Chemistry, University of Strathclyde, CathedralStreet, Glasgow, GI IXL.and G. S . FELLDepartment of Clinical Biochemistry, Royal Infirmary, Glasgow, G4 OSF.Analyst, 1979, 104, 491-504Vi SUMMARIES OF PAPERS I N THIS ISSUEEffect of Stray Light in Monocliromators on Detection Limits ofJune, 1979Flame Atomic-fluorescence Spectrometric MeasurementsQuantitative results are described that demonstrate that the use of a doublemonochromator to reduce stray light originating from strong thermal emissionin the flame gives significant reductions in noise on the background of thefluorescence measurement.This leads to worthwhile improvements indetection limit for all elements with analytically useful resonance lines a twavelengths shorter than approxima,tely 250 nm. The degree of improve-ment depends upon whether water or a real sample is being aspirated. Forthe determination of cadmium in uri:ne the detection limit is improved by afactor of three and for the determination of selenium in water the improve-ment is a factor of 5-6. Scatter of excitation source radiation is also shownto have a small but significant effect on detection limits when using electrode-less discharge lamps as source. Scatter is more serious in the air - hydrogenflame than the air - acetylene flame.Keywords : Flame atomic-fluorescence spectrometry ; stray light ; double mono-chromatorR.G. MICHEL, M. L. HALL, S. A. K. ROWLAND, J. SNEDDON and J. M.OTTAWAYDepartment of Pure and Applied Chemistry, University of Strathclyde, CathedralStreet, Glasgow, G1 1XL.and G. S. FELLDepartment of Clinical Biochemistry, Royal Infirmary, Glasgow, G4 OSF.Analyst, 1979, 104, 505-515.Sequential Multi-element Analysis of Small Fragments of Glassby Atomic-emission Spectrometry Using an Inductively CoupledRadiofrequency Argon Plasma SourceA method is described for the quantitative multi-element analysis of smallfragments (200-500 pg) of glass using an inductively coupled radiofrequencyargon plasma source. The glass samples are digested with a mixture ofhydrofluoric and hydrochloric acids and chromium is added as an internalstandard.An ultrasonic nebuliser is used in order to reduce to a minimumthe volume of solution required for eaxh analysis. A single monochromatorand detection system is employed, and the wavelength regions of interestare examined sequentially by means of a specially constructed control unit.The results for aluminium, barium, iron, magnesium and manganese showthat the analysis of glass fragments in the range 200-500 pg can be achievedwith coefficients of variation of approximately 10%. Standard glasses wereanalysed to assess the accuracy of the method.Keywords : Glass analysis ; acid digestion ; control unit for automatic sequentialselection of wavelength regions ; iwductively coupled radiofrequency argonplasma; forensic analysisT.CATTERICK and D. A. HICKMANThe Metropolitan Police Forensic Science Laboratory, 109 Lambeth Road, London,SE1 7LP.Analyst, 1979, 104, 516-524June, 1979 SUMMARIES OF PAPERS I N THIS ISSUESpectrophotometric Determination of Trace Amounts of Free Cyanidein Prussian BlueviiTrace amounts of free cyanide in Prussian blue are hydrolysed into hydro-cyanic acid. The latter is captured by a lithium picrate solution containedin a test-tube, which is placed in the reaction vessel. The colour changedue to the resulting lithium isopurpurate is measured spectrophotometricallyat 500nm. This method can detect cyanide down to a level of 2.5 pg in100 mg of Prussian blue and is accurate and reproducible.Keywords : Cyanide determination ; insoluble and colloidal Prussian blue ;spectrophotovnetvyG.J. WILLEKENS and A. VAN DEN BULCKEInstituut voor Hygiene en Epidemiologie, Departement Farmatoxicologie, AfdelingFarmacopee- en Standaardenonderzoek, Juliette Wytsmanstraat 14, 1050 Brussels,Belgium .Analyst, 1979, 104, 525-530.Polarography of Green SThe food dye Green S, 4-[4-dimethylammoniocyclohexa-2,5-dienylidene-(4-dimethylaminophenyl)methyl]-3-hydroxynaphthalene-2,7-disulphonic acid,monosodium salt, is reduced a t the dropping-mercury electrode from 50%ethanolic solutions with the total consumption of two electrons. Polarogramsfollow theoretical predictions in the pH range 2.7-8.75. The reductionmechanism involves two electron transfer steps that are sufficiently differenti-ated at higher pH for separate waves to appear.Keywords : Green S ; food dye ; polavographyF.E. POWELLDepartment of Science and Food Technology, Grimsby College of Technology, NunsCorner, Grimsby, South Humberside, DN34 5BQ.Analyst, 1979, 104, 531-537.Determination of Nitrogenous Gases Evolved from Soils inClosed SystemsA simple method is described for determining nitrogen oxide and nitrogendioxide, evolved from soils, in closed systems. These gases are absorbed byan acidic solution of potassium permanganate, and the resulting nitrate isdetermined by a steam distillation method. Excess of permanganate isreduced with iron(I1) sulphate and neutralised with sodium hydroxidesolution. Ammonium in solution is removed by distillation with magnesiumoxide, and nitrate is determined by distillation after reduction to ammoniumby Devarda's alloy.Nitrogen and dinitrogen oxide evolved from soils are measured using gaschromatography on a single 0.61-m column of molecular sieve 5A, tempera-ture programmed to 250 "C at 39 "C min-1, after an initial period of 1 mina t 35 "C. A complete analysis requires 19.5 min, and 2 pg of nitrogen canbe determined quantitatively for each gas.Keywords : A cidic permanganate ; gas chromatography ; nitrogenous gases ;steam distillation ; soilsC. J. SMITH and P. M. CHALKSchool of Agriculture and Forestry, University of Melbourne, Parkville, Victoria3052, Australia.Analyst, 1979, 104, 538-544