Spectrofluorimetric methods

Spectrophotometric and spectrofluorimetric methods provide a wealth of information concerning structural determinations (identification, purity and precise measurement of concentration) and chemical changes in alkaloids. These techniques yield both quantitative and qualitative data on the effect of solvents, pH and other physiological conditions [141-143]. X-ray crystallography, H and NMR spectroscopy, infrared spectroscopy (IR) and circular dichroic spectroscopy were also used to study the physical properties... 

Khashaba et al. [34] suggested the use of sample spectrophotometric and spectrofluorimetric methods for the determination of miconazole and other antifungal drugs in different pharmaceutical formulations. The spectrophotometric method depend on the interaction between imidazole antifungal drugs as -electron donor with the pi-acceptor 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, in methanol or with p-chloranilic acid in acetonitrile. The produced chromogens obey Beer s law at Amax 460 and 520 nm in the concentration range 22.5-200 and 7.9-280 pg/mL for 2,3-dichloro-5,6-dicyano-l,4-benzoquinone and p-chloranilic acid, respectively. Spectrofluorimetric method is based on the measurement of the native fluorescence of ketoconazole at 375 nm with excitation at 288 nm and/or fluorescence intensity versus concentration is linear for ketoconazole at 49.7-800 ng/mL. The methods... 

Gu et al. [27] used a spectrofluorimetric method for the determination of the long-acting antimalarial primaquine octanoate. 

The first spectrofluorimetric methods reported for the determination of nalidixic acid and its metabolites in biological fluids did not differentiate between nalidixic acid and hydroxynalidixic acid. The determination of free nalidixic acid and the hydroxy-metabolite in human urine plasma and feces was performed by extraction by toluene from acidified biological fluid and subsequent fluorimetric measurement at 325/375 nm of sample re-extracted into aqueous solution.(8) Conjugated nalidixic and hydroxynalidixic acids were determined by acid hydrolysis and then toluene extraction for fluorimetric measurement of the total drug. The conjugated nalidixic acid was then determined by difference. 

Spectrofluorimetric methods are applicable to the determination of aliphatic hydrocarbons, and humic and fulvic acids in soil, aliphatic hydrocarbons polyaromatic hydrocarbons, optical whiteners, and selenium in non-saline sediments, aliphatic aromatic and polyaromatic hydrocarbons and humic and fulvic acids in saline sediments. The only application found in luminescence spectroscopy is the determination of polychlorobiphenyl in soil. Generally speaking, concentrations down to the picogram (pg L 1), level can be determined by this technique with recovery efficiencies near f00%. 

Electrophoretic and isotachoelectrophoretic techniques are gaining in popularity in soil analysis with applications to polyaromatic hydrocarbons, polychlorobiphenyls, tetrahydrothiophene and triazine herbicides, Paraquat and Diquat and growth regulators. Other lesser-used techniques include spectrophotometric methods (five determinants), spectrofluorimetric methods (two determinants), luminescence methods (one determinant), titration methods (one determinant), thin-layer chromatography (five applications), NHR spectroscopy (two applications) and enzymic immunoassays (one determinant). 

Cholerton, S., Idle, M E., Vas, A., Gonzalez, F.J. Idle, J.R. (1992) Comparison of a novel thin-layer chromatographic-fluorescence detection method with a spectrofluorimetric method for the determination of 7-hydroxycoumarin in human urine. J. Chromatogr., 575, 325-330 Cohen, A.J. (1979) Critical review of the toxicology of coumarin with special reference to interspecies differences in metabolism and hepatotoxic response and their significance to man. Food chem. Toxicol, 17, 277-289... 

Bailey, B. W R. M, Dagnall, and T. S. West Analytical Applications of Ternary Complexes. III. A Spectrofluorimetric Method for the Determination of Submicrogram Amounts of Copper. Talanta 13, 1661 (1966). 

A simple, rapid, sensitive, and selective spectrofluorimetric method (2ex/ lem = 345/455nm) has been developed for the determination of zaleplon. Tang et al. have studied the influence of micellar medium on the absorption, fluorescent excitation, and emission spectra character of zaleplon The nonionic surfactant of Triton X-100 showed a strong sensitizing effect for the fluorescence of zaleplon in a pH 5.0 buffer. The possible enhancement mechanism was discussed. Based on the optimum conditions, the linear range was 1.32 x 10 8-1.00 x 10 mol/1. The detection limit was 4.0 x 10 mol/1 with a relative standard deviation (RSD) of 0.06%. The proposed method was successfully applied to the determination of zaleplon in tablets, serum, and urine. 

Carrillo F, Perez C, Camara C. 1992. Sensitive flow-injection-spectrofluorimetric method to determine aluminium III in water. Anal Chim Acta 262 91-96. 

Brennan et al. used a method to detect the reaction of acetylcholineesterase with acetylcholine [46]. The method was based on the use of a monolayer, consisting of fatty acids having Ci6 chain lengths, which were covalently attached to quartz wafers and which contained a small amount of nitrobenzoxadiazole dipalmitoyl phosphatidylethanolamine (NBD-PE) (partitioned from water into the membrane). The enzyme substrate reaction produced a decrease in fluorescence intensity from the monolayer, and the detection system was sensitive to the changes in bulk concentration of as small as 0.1 pM, with a limit of detection of 2 pM of acetylcholine. The mechanism of transduction of the enzymatic reaction was investigated using spectrofluorimetric methods and fluorescence microscopy. 

Umapathi et al. used spectrofluorimetric methods for the estimation of aspirin and dipyridamole in pure admixtures and in dosage forms [36]. The methods are described for the determination of the two drugs in pharmaceutical preparation without prior separation from each other... 

Capitan-Vallvey et al. [43] has developed a spectrofluorimetric method for the quantitative determination of flufenamic, mefenamic and meclofenamic acids in mixtures by recording emission fluorescence spectra between 370 and 550 nm with an excitation wavelength of 352 nm. The excitation-emission spectra of these compounds are deeply overlapped which does not allow their direct determination without previous separation. The proposed method applies partial least squares... 

The levels of haem proteins in biopsy material, in plasma and bound to membranes can be determined to a level of 0.01 fig, applying the following spectrofluorimetric method (Morrison, 1965). 

Clinical measurements of lithium may be performed using atomic absorption spectrometry (AAS) or flame emission spectrometry (FES) 64). AAS is regarded as the more reliable of the two techniques for blood lithium. FES is rather more sensitive, but suffers from interference from the high sodium and potassium concentrations in blood. Recent developments include inductively coupled plasma (ICP) emission spectrometry, electrothermal atomization atomic absorption spectrometry (ETAAS), and spectrofluorimetric methods. Spectrofluorime-try and ETAAS offer greater sensitivity than the traditional methods and are useful research tools 65, 66). 

A. Sanz, V. Tomas, C. Martinez-Lozano, T. Perez-Ruiz, Extraction-spectrofluorimetric method for the determination of erythromycin and its esters in pharmaceutical formulations using manual and flow-injection procedures, Analyst 118 (1993) 567. 

Abdellatef, H.E. (2007) Spectrophotometric and spectrofluorimetric methods for the determination of ramipril in its pure and dosage form. Spectrochim Acta Part A, 66 (3), 701-706. 

D., Resolution of benzo[a]pyrene in complex mixtures of other polycyclic aromatic hydrocarbons. Comparison of two spectrofluorimetric methods applied to water samples. Analyst, 125, 1321 -1326, 2000. 

The UV methods reported minimum detectable limits of q)proximately 0.5 pg/mL. The development of a spectrofluorimetric method 305 nm, 505 nm) lowered this limit to 0.1 pg/mL [36]. 

Ragos G. C., Demertzis M. A. and Issopoulos P. B. (1998) A high-sensitive spectrofluorimetric method for the determination of micromolar concentrations of iron(III) in bovine liver with 4-hydroxyquinoline. II Farmaco, 53, 611-616. 

A variety of methods for quantitative determination of major opium alkaloids have been reported by different workers, such as gravimetric/ volumetric methods, colorimetric methods, spectrofluorimetric methods, etc. However, separation is usually achieved by thin layer (TLC) or paper chromatography (PC). Today, advanced analytical methods, like gas (GLC)/high performance liquid chromatography (HPLC) are more frequently employed for this purpose. In the following sections, we describe these methods briefly, with greater emphasis on GLC and HPLC. 

Spectrofluorimetric method was reported by Chalmers and Wadds (1970) for the estimation of opium alkaloids in micro amounts where morphine, codeine, papaverine and narcotine mixtures are determined spectrofluorime-trically in 2.5 h with 7% relative errors. Morphine and codeine are determined by a differential method involving fluorescence measurements in 0.1 N sulfuric acid and 0.1 N sodium hydroxide solutions, after the papaverine and narcotine were extracted into chloroform from the sample solution in 0.1 N sulfuric acid. Then papaverine and narcotine are determined after extraction at pH 9. Trichloroacetic acid is used for simultaneous enhance-... 

Recent developments include inductively coupled plasma emission spectrometry (ICP), electrothermal atomic absorption spectrometry (ETAAS), and spectrofluorimetric methods. 

Haydak et al. (1942) measured the eoneentration of vitamins Bi, B3 and Bg in honey using speetroseopie methods previously developed by Hennessey and Cerecedo (1939), Melniek and Field (1940) and Seudi (1941), respectively, for determinations in animal organs, biological fluids and a number of foodstuffs. The first is a spectrofluorimetric method, while the last two are both colorimetric methods. 

Among these analytical methods, some methods are used to determine vitamin Bi at macro level and also require expensive and sophisticated instruments. On the other hand, a spectrofluorimetric method promises high sensitivity and selectivity, does not need expensive instrumentation and has been widely used in pharmaceutical, food processing and biological analysis. In this chapter, developments of the spectrofluorimetric method are discussed as advanced analytical approaches for the determination of vitamin Bi. 

Spectrofluorimetric methods are more sensitive and selective and have been used extensively to analyse vitamin BI (thiamin). Thiamin is a non-fluorescent compound which can be converted to a fluorescent thiochrome (TC) derivative... 

Several spectrofluorimetric methods have been reported for the determination of thiamin based on the oxidation of thiamin using several oxidants including cyanogen bromide (Fujiwara and Matsui 1953), copper (Perez-Ruiz et al. 1992), mercury(ii) (Martinez-Lozano et al. 1990 Perez-Ruiz et al. 2004), cobalt(ii) (Jie et al. 1993), iron(III) tetrasulfonatophthalocyanine (Chen et al. 1999), perox-idate (Amjadi et al. 2007), horseradish peroxidase (Khan et al. 2009). 

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