Spectrofluorometric

APPENDIX REAL-TIME METHODS FOR ANALYSIS OF LIGAND BINDING Method 1. Spectrofluorometric Method Using Antibody to Fluorescein... 

A novel TLC spectrofluorometric method for identification and determination of selenium in different food samples of animal and vegetable origin has been proposed [30]. The procedure involves the digestion of food sample (1 to 5 g) in the presence of cone. HNO3 (5 ml), 70% HCIO4 (10 ml), and FIjO (10 ml) in a 250-ml Kjeldahl flask reduction of Se(VI) into Se(IV) complexation of the isolated selenium with 23-diaminonaphthene (DAN) extraction of the resultant Se—DAN complex with cyclohexane and spectrofluorometric determination followed by confirmation of the presence of Se in the sample by TLC using thin layers of MN-300 cellulose powder. 

Laughlin et al. [122] analysed chloroform extracts of tributyltin dissolved in seawater using nuclear magnetic resonance spectroscopy. It was shown that an equilibrium mixture occurs which contains tributyltin chloride, tributyl tin hydroxide, the aquo complex, and a tributyltin carbonate species. Fluorometry has been used to determine triphenyltin compounds in seawater [123]. Triph-enyltin compounds in water at concentrations of 0.004-2 pmg/1 are readily extracted into toluene and can be determined by spectrofluorometric measurements of the triphenyltin-3-hydroxyflavone complex. 

The natural fluorescence of CTC and its derivatives has been used extensively to determine small amounts of CTC in biological materials. Kohn (86) showed that the fluorescent complex formed by CTC with calcium ions and barbital could be extracted from animal tissues into an organic solvent and then measured spectrofluorometrically. The intense fluorescence of anhydro-CTC was used by Hayes and DuBuy (87) to determine CTC in animal tissues, tissue culture cells, and bacteria. Poiger and Schlatter (88) extracted CTC from biological material into ethyl acetate as the CTC-calcium trichloroacetate ion pair. The fluorescence of the antibiotic was then enhanced by the addition of magnesium ions and a base. 

No modern studies of the human pharmacokinetics of LSD have been done, largely because human experimentation has virtually stopped. An older study that used a spectrofluorometric technique for measuring plasma concentrations of LSD was done in humans given doses of 2 Mg/kg i.v. After equilibration had occurred in about 30 min, the plasma level was between 6 and 7 ng/ml. Subsequently, plasma levels gradually fell until only a small amount of LSD was present after 8 hr. The half-life of the drug in humans was calculated to be 175 min (2). Subsequent pharmacokinetic analysis of these data indicated that plasma concentrations of LSD were explained by a two-compartment open model. Performance scores were highly correlated with concentration in the tissue (outer) compartment, which was calculated at 11.5% of body weight. The new estimation of half-life for loss of LSD from plasma, based on this model, was 103 min (47). 

Sano A, Takezawa M, Takitani S. 1989. Spectrofluorometric determination of cyanide in blood and urine with naphthalene-2,3-dialdehyde and taurine. Anal Chim Acta 225 351-358. 

Appendix A. Spectrophotometric and spectrofluorometric pH titrations Single-wavelength measurements... 

Appendix B. Determination of the stoichiometry and stability constant of metal complexes from spectrophotometric or spectrofluorometric titrations... 

D. Duggan and S. Udenfriend, The spectrofluorometric determination of tryptophan in plasma and of tryptophan and tyrosine in protein hydrolysates, J. Biol. Chem. 223, 313-319 (1956). 

Spectrofluorometry underpins all luminescent techniques for characterizing the target analyte and the associated sample matrix. LIF occurs from the vacuum UV through the NIR range, but is most common between 250 nm and 800 nm. A typical fluorescent profile contains an absorption spectrum and an emission spectrum as depicted in Figure 11.3. Spectrofluorometric excitation profiling at emission maxima and syn-chronons scanning are common methods to characterize a fluorophore. 

A sample of organolithium compound solution is added to an excess of standardized iodine solution in Et20 the excess iodine is extracted with aqueous KI and titrated with standard thiosulfate solution. Evaluation of the organometallic compound is made according to equation. A possible interference can be expected from the couphng reaction in equation 20. This was shown to be neghgible, as demonstrated spectrofluorometrically for phenyllithium , whereas a low titer was found for n-BuLi, attributable to this side... 

Results obtained by spectrophotometric and spectrofluorometric methods agree closely with each other (Kll) and are sufficiently sensitive and specific for general use. GLC methods are also available (A12) but do not offer any obvious advantage over older methods for clinical use. 

These results may be visualized more simply when plotting the ratio [(OD 250/ OD 270) (cyclophosphazene-DNA)]/[(OD 250/OD 270) DNA] as a function of r (Fig. 25) whereby the trend of the behaviour of the various cyclophosphazenes with respect to EtdBr binding, as revealed by UV spectrophotometry, looks virtually identical to the one provided by the spectrofluorometric study (Fig. 22), especially concerning the existence of the four classes previously mentioned. The batho-hyper-shift is observed only for the terms of the series which induce a fluorescence decrease. 

The HRP-catalyzed oxidation of 2-hydroxy-1-naphthaldehyde salicylhydrazone (116) reported for H2O2 (Section III.B.2.b) can be applied for the spectrofluorometric determination of polyethyleneglycol hydroperoxides327. The method involving fluorescence of a triple complex of A-(a-pyridyl)-2-thioquinaldamide (120) in the presence of V(V) and H2O2 (Section III.B.2.b) can also be applied to the determination of organic peroxides, represented by z-BuOOH. LOD for Z-BuOOH is 0.03 xM, with RSD 2% (n = 3, 0.5 p,M), and linearity in the 0.1 to 2 p,M range330. 

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