Fluorometric measurements

Measured end points are photosynthesis as the incorporation of radiolabelled H C03 ( C) and bacterial activity as the incorporation of radiolabelled thymidine (thym) fluorometric measurements basal fluorescence (Fo) and photon yield (Y) chlorophyll-a concentration (chl-a) species composition (spp) and the biovolume of algae obtained after algal counting (biovolume)... 

Hence, pseudosimultaneous spectroscopic and flow-cytometric measurements suggest that actin polymerization may be functionally related to aggregation, possibly by reorganization of adhesive molecules on the cell surface. Simultaneous spectroscopic and fluorometric measurements suggest that the signal Ca may be related to oxidant production and degranulation. 

Because a chlorophyll molecule contains a closed circuit of ten conjugated double bounds to absorb light, spectrophotometric (UV-Vis) and fluorometric measurements are satisfactory to identify and estimate amounts of chlorophyll a and chlorophyll b, usually the only ones present in fresh plant extracts. The basis of numerous spectrophotometric determinations reported in literature is that chlorophylls strongly absorb at 500 to 700 nm in the visible region and show a large typical band around 400 nm. 

Lin, E.L.C., S.M. Cornier, and R.N. Racine. 1994. Synchronous fluorometric measurement of metabolites of polycyclic aromatic hydrocarbons in the bile of brown bullhead. Environ. Toxicol. Chem. 13 707-715. 

The oxidation process of H2O2 by Ce(IV) depicted in equation 38 may be followed by the change in absorbance of this ion however, a more sensitive determination is based on the fluorometric measurement of Ce(III) (X x = 260 nm, ka = 360 nm). The reaction should be carried out in acid medium (pH 1-2) and care should be taken that total conversion of Ce(IV) to Ce(III) has been accomplished, lest Ce(IV) absorbs part of the emitted fluorescence. The LOQ of the method is 0.1 ppm °. 

Many specific and highly sensitive fluorometric and electrochemical detection methods for various analytes are available. The combination of such detection schemes with a DS-based collection system provides a combination of sensitive and affordable instrumentation for atmospheric measurements. A step-by-step construction and operation manual for a DS-based fluorometric H202 analyzer is available (94). With a change in the reagents, the calibration source, and the conditions of the fluorometric measurement, such an instrument is readily reconfigured for a different analyte. The 1992 fabrication cost of a complete DS instrument that utilizes fluorometric detection and includes a thermostated calibration source from commercially available components is approximately 12,000. 

P.J. Barnes and R.G. Fulcher, Fluorometric Measurement of Fats. In L. Munck (ed.), Fluorescence Analysis in Foods, Longman Scientific and Technical, New York, (1989).p207. 

Fig. 8. Principle of time-resolved fluorometric measurement with delay time of 200 ps, counting time of 400 ps, and...

Winer, A.D., Schwert, G.W. and Millar, D.B.S. Lactic dehydrogenase. VI. Fluorometric measurements of the complex of enzyme and reduced diphosphopyridine nucleotide. 

Yasumoto, T, and Takizawa, A. 1997. Fluorometric measurement of yessotoxins in shellfish by high-pressure liquid chro-matogrq)hy. Biosci Biotechnol Biochem 61, 1775—1777. 

Phospholipid-Free Extracts. The preliminary extraction of plasma with diisopropyl ether and silicic acid is based on the procedure of Mendelsohn and Antonis (M2) (described previously under the section for the fluorometric measurement of cholesterol). These phospholipid-free chloroform extracts are stable indefinitely if stored at 4°C. 

G17. Greenberg, L. S., Fluorometric measurement of alkaline phosphatase and amino-peptidase activities in the order 10 mole. Biochem. Biophys. Res. Commun. 9, 430-435 (1962). 

H6b. Hayashi, Y., and Makino, M., Fluorometric measurement of glycosylated albumin in human serum. Clin. Chim. Acta 149, 13-19 (1985). 

The fluorometric procedure is the official AO AC method most commonly used for the determination of histamine (AOAC Methods, 1980). The method involves extraction of the fish with methanol, separation of histamine from amino acids by passing the extract through an ion-exchange column, and reaction with o-phthalaldehyde under controlled conditions, followed by fluorometric measurement. This method has proven to be accurate and sensitive, with a detection limit of approximately 1 mg hista-mine/100 g fish sample (Gouygou et ai, 1992). Drawbacks are that it is rather slow (maximum four or five samples per hour) and requires strict handling. 

Humphrey A (1988) The potential of on-line fluorometric measurements for the monitoring and control of fermentation systems. Aust J Biotechnol 2 141 -147... 

NB No details were given of the pH meter calibration. Fluorometric measurements were used to assess the pJCa values for flie first excited state. Used previously described spectrophotometric titration procedures Cappomacchia A, Casper J and Schulman SG, /. Pharm. ScL, 63, 1272-1276 (1974). 

M) most often employed in fluorometric measurements, the following equation relating F and c can be derived [2, 4] ... 

Degelau A, Scheper T, Bailey JE, Guske C (1995) Fluorometric measurement of poly-P-hydroxybutyrate in Alcaligenes eutrophus by flow cytometry and spectrofluorometry. Appl Microbiol Biotechnol 42 653-657... 

An even more sensitive reagent for this purpose was introduced by S. Udenfriend and collaborators in 1972, M. Weigele s fluorescamine (III in Fig. 4) which at room temperature with primary amines quickly forms strongly fluorescent pyrrolinones (IV) fluorometrically measurable even in the picomole range [14]. 

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