Fluorescamine, analytical methods

Two further analytical methods are based on the formation of metal complexes. Reaction of dopamine with KzCrjOy gives a Cr complex which can be assayed by atomic absorption spectroscopy, carbon rod absorption spectroscopy or, if Kf CrjO has been used, by liquid scintillation spectroscopy. Since the complex still gives a reaction with fluorescamine, the side-chain is thought not to be involved in the formation of the complex. Methamphetamine hydrochloride can be precipitated as a Bi complex. Determination of the amount of Bi remaining in solution by atomic absorption spectroscopy provides an indirect method of assay for the amphetamine. ... 

The available data on the primary specificity of pepsin may be summarized in terms of a strong preference for two aromatic L-amino acid residues forming the sensitive X-Y bond, the best substrates being those in which X= Phe and Y = Trp, Tyr, or Phe. The introduction of a Phe(4N02) residue in the X-position did not alter markedly the kinetic parameters of pepsin action this permitted the development of a spectrophotometric method for following the hydrolysis of the Phe(N02)-Phe bond (6). In contrast to the widely used analytical procedures for estimating the rate of formation of the amine product (e.g., Phe-OMe) by means of its reaction with ninhydrin or fluorescamine, this method measures the rate of formation of the acidic product e.g., Z-His-Phe(4N02). 

Saxitoxin has been labeled with fluorescamine, o-phthaldialdehyde (OPA) and dansyl chloride and detection limits as low as 0.1 attomole were reported for the OPA derivative of saxitoxin (26). Labeling, separation, and analysis of saxitoxin was best accomplished using fluorescamine, which produces ionic derivatives that can be separated from other fluorescently labeled marine toxins, such as tetrodotoxin and microcystin. However, the precolumn labeling methods required xM concentrations of analyte, limiting the utility of the technique for trace analysis. 

Many derivatization techniques, based on chemical reactions or even heat and chemical reactions, can be applied to TLC or HPTLC to specifically determine some compounds or groups of compounds this is specific to TLC techniques. For instance, exposure to fluorescamine in acetone wiU convert sulfonamide antibiotics into fluorescent derivatives which can be visualized under UV radiation [8]. Other techniques are reported and, as suggested earher, the reader should refer to the latest edition of the Official Methods of Analysis pubhshed by the Association of Official Analytical Chemists (Arlington VA, U.S.A.) for complete details about aU the available techniques for the routine analysis of drugs. 

Most amino acids react with ninhydrin at ambient temperatures to form a blue color that becomes purple on heating. However, proline and hydroxyproline yield yellow compounds that are measured at a different wavelength. Other postcolumn derivatizations use fluorogenic reagents, such as o-phthaldialdehyde or fluorescamine. Precolumn derivatization techniques using o-phthaldialdehyde, dansyl, phenyl isothiocyanate, or 9-fluorenylmethyl chloroformate derivatives have been used with reversed-phase HPLC. Electrochemical detection has also been coupled with derivatization methods to enhance analytical sensitivity. 

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