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The results of the present study support this assumption.Cyanocobalam indid not emit the corr in phos phorescence irrespective of the excitation energy and at temperatures down to K.In addit ion the quan tumyie ld of pho toaquationdid not depend on theirradiating wavelengths.The low quan tum yie ld of pho toaquation of cyanocoba lam in means then that either the deactivation of the excitedcorr in singlets leads to the lowest excited LF singlet which does not undergo efficient intersystem crossing to the reactive LF triplet or, morelike ly, the popu lation of the reactive tr ip let is very effective, however, its deactivation does not on ly occur by the pho toreaction but also by an efficient rad iation lesstransit ion to the ground state.Alter natively, the reactive LF state may not be populated at a ll because its energy is toohigh.The quenching of thecorr in phosphorescence of corr in by oxygen shou ld have the sameor ig in.The relativeordering of different excited states and also energy differences between them can not on ly be var ied by an exchange of the metal but also by an appropriate choice of the ligands. If bo th axial cyanide ligands wh ich are strongfield ligands are replaced by the weakfieldligand ch loride the lowest excited LF state is expected todrop cons iderab ly in energy.The former can now be populated from thecorr in triplet by thermal activation.Consequently, a strongcorr in phosphorescence was observed at low temperatures while atro om <a href="http://www.targetmol.com/compound/Lansoprazole">buy Lansoprazole</a> temperature this emission was essentially quenched and the comp lex underwent a pho toaquation.Congr. Pure App l. Chem, Boston, Suppl. Pure App l. Chem, E The user has requested enhancement of the downloaded file.In the case of ICPAES and IC, a prerequisite for   quality measurement is the purity of the starting vitamin B material.Vitamin B deciency may lead to excessive tiredness, and poor resistance to infection.Prolonged deciency leads to nerve degeneration and irreversible neurological damage.The daily requirement of this vitamin is only as low as to mg.On the other hand, excessive consumption of vitamin B may cause asthma and folic acid deciency.So, the cyanocobalamin content requires very precise determination at nano to pico gram levels in many areas of application like clinical, pharmaceutical and food products.Various analytical methods including microbiological assay, radioisotope dilution assay, spectrophotometry, chemiluminescence, atomic absorption spectrometry, matrix assisted laser desorption ionizationtime of ight mass spectrometry, high performance liquid chromatography with mass spectrometry, and uorescence detection have been proposed for the determination of vitamin B.Although these methods are routinely used for many applications, they are not deemed appropriate for high accuracy and precise measurements to underpin materials that are meant to be used as primary standards and highcaliber certied reference materials of vitamin B.Despite the availability of numerous vitamin B assays, there remains a continuing need for an SI traceable reference method, as traceability is an important parameter of reference materials.Traceability ensures quantitation comparability between dierent laboratories, dierent instrumental techniques, and measurement made at dierent times.Though these methods are used successfully in various matrices routinely for B determination with accuracy between, they are not suitable for providing relative expanded uncertainties of.

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