Fluorescence determination

Irvine AML, Smith I W M, Tuckett R P and Yang X-F 1990 A laser-induced fluorescence determination of the complete internal state distribution of CH produced in the reaction H + NG2 CH + NC J. Chem. Phys. 93 3177-86... 

SORBTION-X-RAY-FLUORESCENCE DETERMINATION OE TOXIC METALS WITH THEIR PRECONCENTRATION ON COMPLEXING CHEMICAL MODIEIED SILICA... 

Variety of biochemical composition and physical features of milk, as well as compound forms of mineral components foreordain necessity to develop the analytical procedures, in which initial sample state suffers minimum change. Absence of dried milk reference standai ds (RSMs) is an obstacle to use nondestructive XRF for solving the given analytical task. In this communication results of nondestmctive x-ray fluorescence determination of Na, Mg, Al, Si, P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Zr in dried milk powders of limited mass (less than 2 g), obtained with using plant RSMs to calibrate, ai e discussed. 

ACID-BASED SURFACTANT CLOUD POINT EXTRACTION AND PRECONCENTRATION OF POLYCYCLIC AROMATIC HYDROCARBONS PRIOR TO FLUORESCENCE DETERMINATION... 

X-RAY FLUORESCENCE DETERMINATION OE MINOR AND TRACE ELEMENTS IN VARIOUS TYPES OE ROCKS, SOILS AND SEDIMENTS BY PIONEER SPECTROMETER... 

Figure 8. Simultaneous measurement of intracellular Ca and oxidant production in neutrophils. Cells were labeled with Quin-2 and suspended at 2 x lo cells/mL buffer. At time zero, 1 nJf FLPEP was added (upper trace in each panel). In addition, the receptor blocker tBOC was added (3 x 10" M) after 30 s to stop further binding of the stimulus (lower trace in each panel). The excitation wavelength was 3A0 nm. Top panel Quin-2 fluorescence determined on channel B (of Figure 1) using a Corion A90-nm interference filter. The crossover from the superoxide assay has been subtracted. Middle panel Oxidant production (superoxide equivalents) determined by the para-hydroxyphenylacetate assay. Fluorescence was observed at AOO nm (on channel A of Figure 1).

Arsenic was added to an American Cyanamld HDS-2 catalyst for comparison with a used catalyst containing 3.6% As. This used catalyst was also an American Cyanamld HDS-2 catalyst which had been In service In a refinery distillate HDS unit for about six years. Again, X-ray fluorescence determined compositions are In Table I. 

Axelrod HD, Cary JH, Bonelli JE, et al. 1969. Fluorescence determination of sub-parts per billion hydrogen sulfide in the atmosphere. Anal Chem 43 1856-1858. 

Li H, Xu J, Yan H (2009) Ratiometric fluorescent determination of cysteine based on organic nanoparticles of naphthalene-thiourea-thiadiazole-linked molecule. Sensor Actuat B-Chem... 

Among other factors, the quantum yield of fluorescence determines the intensity of light emission in a CL. This, as well as the position in the spectrum occupied by the fluorescence band, is largely a function of the molecular structure. 

Fluorescence determinations are best made on samples of homogeneous particle size, and this is not the normal state of soil. Grinding and carefully sieving soil before analysis can minimize problems associated with particle size heterogeneity. Another approach has been to fuse soil with borate or to dilute it with cellulose or other suitable diluents. Very thin layers of soil may also be prepared and used for quantitative analysis. 

Other limitations involve both the mass absorption coefficient of soil components and secondary and tertiary excitation. The mass absorption coefficient can be calculated and used to correct fluorescence determinations if the exact composition of the material being analyzed is known. This is not possible in soil. Secondary and tertiary excitations occur when X-rays emitted by an element other than the one of interest may cause emission or fluorescence of the element of interest. These potential sources of error are possible in any soil analysis using XRF. 

Becker, K. H., U. Schurath, and T. Tatarczyk. Fluorescence determination of low formaldehyde concentrations in air by dye laser excitation. Appl. Optics 14 310-313, 1975. 

The fluorescence of liquid alkanes is supposed to originate entirely from the relaxed Si state. Walter and Lipsky [154], by measuring the fluorescence yields of alkane solutions irradiated with 165 nm photons or Kr beta particles ( niax = 0-67 MeV) relative to benzene fluorescence, determined the following yields 2.3-dimethylbutane G Si) < 1.3, cyclohexane 1.4-1.7, methylcyclohexane 1.9-2.2, dodecane 3.3-3.9, hexadecane 3.3-3.9, d5-decalin 3.4, and bicyclohexyl 3.5. After reinvestigating the intrinsic quantum yield of cyclohexane fluorescence, Choi et al. published G(5 i) = 1.45 for this alkane in Ref. 155. For tra 5-decalin a G Si) value of 2.8-3.1 has been accepted [65,128,132]. The uncertainties in the values reflect the uncertainties in the intrinsic fluorescence quantum yields. 

Rose, H. J., and Flanagan, F. J., X-ray fluorescence determination of thallium in manganese ores. "U. S. Geological Survey Professional Paper A50-B," 1962, 80-82. 

Fluorescence determinations are important to analyze cysteine, guanidine, proteins, (LSD), steroids, a number of enzymes and coenzymes, and some vitamins, as well as several hundred more substances. A fluorometer can be used to verify conformational changes in multipartite operator recognition by. -repressor as explained in a journal article by Deb et al. (2000). Upon titration with single operators site, the tryptophan fluorescence quenches to different degrees, suggesting different conformations of the DNA-protein complexes. 

Gatti R, Roda A, Cerre C, Bonazzi D, Cavrini V (1997) HPLC-fluorescence determination of bile acids. Biomed Chromatog 11 11-15... 

Yan, B Li, W. Rapid Fluorescence Determination of the Absolute Amount of Aldehyde and Ketone Groups on Resin Supports, J. Org. Chem. 1997,62, 9354. 

Carbamates and substituted ureas are a numerous group of pesticides widely used to control weeds, pests, and diseases in fruit trees, vegetables, and cereals. Carbamate residues in foods are commonly extracted with water-miscible solvents and determined by using a liquid chromatograph equipped with a sensitive detector, frequently a UV detector. In addition, to obtain adequate detection selectivity, the postcolumn fluorimetric labeling technique is used for methyl carbamates. Substituted ureas are normally extracted from foods with organic solvents, and they can be determined directly by HPLC-UV or after postcolumn derivatization by fluorescence determination of their derivatives. 

Simon-Lukasik, K. V., Persikov, A. V., Brodsky, B., Ramshaw, J. A., Laws, W. R., Ross, A., and Ludescher, R. D. (2003). Fluorescence determination of tryptophan side-chain accessibility and dynamics in triple-helical collagen-like peptides. Biophys. J. 84, 501-508. 

Take 5 pL of the transcribed ubiquitin mRNA and dilute 200-fold with TE. Mix the diluted mRNA with 100 pL of RiboGreen Reagent, and measure fluorescence. Determine the concentration of the mRNA by comparing the intensity of fluorescence with the standard curve determined above. 

The effect of pH on the fluorescence of ciprofloxacin and norfloxacin has been studied, and the ground-state microscopic dissociation constants were determined [14]. After their acidic solutions (pH 2-4) were allowed to stand for 5 min at 25°C, the optimum wavelength for fluorescence determinations was found to be 445 nm (excitation at 280 or 331 nm) of these compounds. 

A. Martinez, A. Morales-Rubio, M. L. Cervera, M. de la Guardia, Atomic fluorescence determination of total and inorganic arsenic species in beer, J. Anal. Atom Spectrom., 16 (2001), 762-766. 

Likewise, the luminescence properties of many analytes can be altered in the presenoe of surfactant aggregates (4,7.,8.). Consequently, addition of micelle-forming surfactants (present either in the LC mobile phase or added post-column) can improve the sensitivity of fluorimetric LC detectors (49,482). Micellar spray reagents have been utilized to enhance the fluorescence densitometric detection of dansylamino acids or polycyclic aromatic hydrocarbons (483). The effect was observed for TLC performed on cellulose or polyamide stationary phases with the micellar spray reagent being either CTAC, SB-12, or NaC (483). More recently, use of nonionic Triton X-100 has been found to improve the HPLC detection of morphine by fluorescence determination after post-column derivatization (486) as well as improve the N-chlorination procedure for the detection of amines, amides, and related compounds on thin-layer chromatograms (488). 

Twenty-two copper-based coins of the Roman Republic were analyzed for Fe, Co, Ni, Cu, Zn, As, Ag, Sn, Sb, and Pb by using X-ray fluorescence according to the procedures described by Carter and Booth (11). Generally, X-ray fluorescence determines elements only in a thin surface layer, about 5-10 xm deep, so it was necessary to clean coins for analysis in such a way that the surface layer was as representative of the entire coin as possible. First, the coins were cleaned by electrolytic reduction in a hot solution of sodium carbonate. Next, the coins were abraded in an air stream containing finely divided aluminum oxide powder to remove about 10 to 15 xm of metal. Carter and Booth described the cleaning procedure in detail as well as the X-ray fluorescence parameters (11). 

Figure 9.37 Fluorescent determination of catalytic activity in the Heck coupling of the labeled substrate 9.92 with supported 9.93 validation studies versus Heck couplings in solution.

G.M. Perez-Howard, P.A. Weil and J.M. Beechem. Yeast TATA binding protein interaction with DNA fluorescence determination of oligomeric state, equilibrium binding, on-rate, and dissociation kinetics. Biochemistry 34 (1995) 8005-17. 

H -tetramethylbenzidine in anionic-cationic mixed micelles has been studied in detail by ESR . The photochemistry of the semi-oxidised forms of eosin Y and rose bengal have been investigated in colloidal solutions. Relevant to the fluorescence of proteins is a study of fluorescence quenching of indolic compounds by amino-acids in SOS, CTAB, and CTAC micelles O Rate constants for proton transfer of several hydroxyaromatic compounds have been measured in a variety of surfactant solutions. Photoprotolytic dissociation does not require exit of the reactant molecules from the micelles. Micellar solutions can be used to improve the fluorescence determination of 2-naphthol by inhibiting proton transfer or proton inducing reactions z2. jpe decay of the radical pair composed of diphenylphosphonyl and 2,4,6-trimethyl benzoyl radicals in SDS is affected by magnetic... 

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