High-performance liquid measurement

J. B. Wheatley, J. A. Montali and D. E. Schmidt-Jr, Coupled affinity-reversed-phase high-performance liquid cliromatography systems for the measurement of glutathione 5-transferases in human tissues , 7. Chromatogr. A 676 65 - 79 (1994). 

G. Ziircher and M. Da Prada, Simple automated high-performance liquid cliromato-graplric column-switching tecnique for the measurement of dopa and 3-O-methyldopa in plasma , 7. Chromatogr. 530 253-262 (1990). 

More recently, the reaction advancement of resole syntheses (pH = 8 and 60°C) was monitored using high-performance liquid chromatography (HPLC), 13C NMR, and chemical assays.55,56 The disappearance of phenol and the appearances of various hydroxymethyl-substituted phenolic monomers and dimers have been measured. By assessing the residual monomer as a function of reaction time, this work also demonstrated the unusually high reactivity of 2,6-dihydroxymethyl-phenol. The rate constants for phenolic monomers toward formaldehyde substitution have been measured (Table 7.6). 

In 1979, it was stated that poiybrominated aromatic ethers have received little attention (ref. 1). That statement is still applicable. Analyses to characterize this class of commercial flame retardants have been performed using UV (refs. 1-2), GC (refs. 1-6), and GC-MS (refs. 1-4). The bromine content of observed peaks was measured by GC-MS, but no identification could be made. The composition of poiybrominated (PB) diphenyl ether (DPE) was predicted from the expected relationship with polyhalogenated biphenyl, a class which has received extensive attention. NMR (refs. 3-6) was successfully used to identify relatively pure material which had six, or fewer, bromine atoms per molecule. A high performance liquid chromatography (HPLC) method described (ref. 1) was not as successful as GC. A reversed phase (RP) HPLC method was mentioned, but no further work was published. 

Quantitation in high performance liquid chromatography, as with other analytical techniques, involves the comparison of the intensity of response from an analyte ( peak height or area) in the sample under investigation with the intensity of response from known amounts of the analyte in standards measured under identical experimental conditions. 

While the apparent molecular weight was about 47,000 g/mol or daltons (Da) by mobUify on SDS-PAGE, separate analysis by sedimentation equilibrium measurements and capillary high-performance liquid chromatography (HPLC) in SDS buffer gave values near 23,000 Da. 

MAiANi G, SERAFiNi M, SALUCCi M, AZZiNi E and FERRO-Luzzi A (1997) Application of a new high-performance liquid chromatographic method for measuring selected polyphenols in hiunan plasma , J of Chromatog B, 692, 311-17. 

MERKEN H M and BEECHER G R (2000) Measurement of food flavonoids by high-performance liquid chromatography A review , JAgric Food Chem, 48 (3), 577-99. 

Lipophilicity represents the affinity of a molecule or a moiety for a lipophilic environment. It is commonly measured by its distribution behavior in a biphasic system, either liquid-liquid (e.g. partition coefficient in 1-octanol-water) or solid-liquid (retention on reversed-phase high-performance liquid chromatography or thin-layer chromatography system). 

The octanol-water parhtion coefficient. Poet (often reported as log Poet), is a particularly useful parameter in quantitative structure-achvity relationships, apphed to predichon of properhes related to drug absorphon, distribution, metabohsm and excrehon [61, 62]. Although the traditional log Poet measurements have been done by the shake-flask method [63, 64], high-performance liquid chromatography-... 

Sangster, J. Octanol-Water Partition Coefficients Fundamentals and Physical Chemistry, Wiley, Chichester, 1997. n Valko, K. Application of high-performance liquid chromatography based measurements of lipophilicity to model biological distribution. J. Chromatogr. A 2004, 1037, 299-310. 

Thompson, S. and Smith, M.T. (1985). Measurement of the diene conjugated from of linoleic acid in plasma by high performance liquid chromatography. A questionable non-invasive assay of free radical activity. Chem. Biol. Interactions 55, 357-366. 

Shigenaga, M.K., Park, J.W., Cundy, K.C., Cimeno, C.J. and Ames, B.N. (1990). In pim oxidative DNA damage, measurement of 8-hydroxy-2 -deoxyguanosine in DNA and urine by high-performance liquid chromatography with electrochemical detection. Meth. Enzymol. 186, 521-530. 

Torsi, G., Chiavari, G., Laghi, C., and Asmudsdottir, A., Responses of different UV-visible detectors in high-performance liquid chromatographic measurements when the absolute number of moles of an analyte is measured, /. Chromatogr., 518, 135, 1990. 

Kolb, A. M., Lentjes, E. G., Smit, N. P., Schothorst, A., Vermeer, B. J., and Pavel, S., Determination of pheomelanin by measurement of aminohydroxypheny-lalanine isomers with high-performance liquid chromatography, Anal. Bio-chem., 252, 293, 1997. 

Soldin, S.J. and Hill, J.G., A rapid micro method for measuring theophylline in serum by reversed phase high performance liquid chromatography, Clin. Biochem., 10,74,1977. 

High Performance Liquid Chromatographic (HPLC) Analysis. A Waters HPLC system (two Waters 501 pumps, automated gradient controller, 712 WISP, and 745 Data module) with a Shimadzu RF-535 fluorescence detector or a Waters 484 UV detector, and a 0.5 pm filter and a Rainin 30 x 4.6 mm Spheri-5 RP-18 guard column followed by a Waters 30 x 3.9 cm (10 pm particle size) p-Bondapak C18 column was used. The mobile phase consisted of a 45% aqueous solution (composed of 0.25% triethylamine, 0.9% phosphoric acid, and 0.01% sodium octyl sulfate) and 55% methanol for prazosin analysis or 40% aqueous solution and 60% methanol for naltrexone. The flow rate was 1.0 mL/min. Prazosin was measured by a fluorescence detector at 384 nm after excitation at 340 nm (8) and in vitro release samples of naltrexone were analyzed by UV detection at 254 nm. 

Chu, Y.Q., Wainer, I.W. (1988). The measurement of warfarin enantiomers in serum using coupled achiral/chiral high performance liquid chromatography. Pharm. Res. 5, 680-683. 

The use of direct UV spectrophotometry to measure sample concentrations in pharmaceutical research is uncommon, presumably due to the prevalence and attractiveness of high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) methods. Consequently, most researchers are unfamiliar with the value of UV detection, mainly that it is generally much faster than other methods - a very important asset in high-throughput screening. 

Kobylinska et al. [62] described a high performance liquid chromatographic analytical method for the determination of miconazole in human plasma using solid-phase extraction. The method uses a solid-phase extraction as the sample preparation step. The assay procedure is sensitive enough to measure concentrations of miconazole for 8 h in a pharmacokinetic study of Mikonazol tablets and Daktarin tablets in human volunteers. The pharmacokinetics of the two formulations was equivalent. 

Hasegawa et al. [76] measured miconazole serum concentration by a high performance liquid chromatographic method. The authors assessed whether the internal standard method produced an intra-assay error and found that the method gave more precise and more reproducible results compared to the absorption calibration curve method. With 0.5 pg/mL of miconazole, the coefficient of variation produced by that method was 3.41%, whereas that of the absorption calibration curve method was 5.20%. The concentration of absorptions calibration curve method showed higher values than the internal standard method. This indicated that the internal standard method was far more precise in measuring the miconazole serum concentrations than the absorption calibration curve method. 

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