By reversed-phase HPLC

PROBLEMS OF SIMILAR COLUMN IN QUANTITATIVE ANALYSIS BY REVERSED-PHASE HPLC... 

Interleukin-2 (recombinant human) [94218-72-1] Mr-15,000, amorphous. Purified by reverse phase HPLC. [Weir and Sparks Biochem J 245 85 1 987 Robb et al. Proc Natl Acad Sci USA 81 6486 1984.]... 

Phenylurea herbicides (urons). Dinocap, Dinoseb, Benomyl, Carbendazim and Metamitron in Waters [e.g. determination of phenylurea herbicides by reverse phase HPLC, phenylurea herbicides by dichloromethane extraction, determination by GC/NPD, phenylurea herbicides by thermospray LC-MS, Dinocap by HPLC, Dinoseb water by HPLC, Carbendazim and Benomyl (as Carbendazim) by HPLC], 1994... 

Purification of the activation products (PMs). The methylamine activation product dissolved in methanol is purified by chromatography, first on a column of silica gel using a mixed solvent of chloroform/ethanol, followed by reversed-phase HPLC on a column of divinylbenzene resin (such as Jordi Reversed-Phase and Hamilton PRP-1) using various solvent systems suitable for the target substance (for example, acetonitrile/water containing 0.15% acetic acid). 

The separation of the main AOS components by reverse phase HPLC provided more qualitative and quantitative information in a single operation than any of the other techniques and can be performed in routine analysis. 

The sulfanes are soluble in carbon disulfide, benzene, tetrachloromethane, and dry diethylether (decreasingly so in that order) while alcohols and aqueous systems initiate rapid decomposition. For this reason a report on the chromatographic separation of the sulfanes H2S by reversed-phase HPLC using methanol as an eluent [35] was shown to be in error The peaks observed in the chromatogram have to be assigned to bismethoxy oligosulfanes... 

Amino acid analysis, by reverse-phase HPLC, of acid-hydrolyzed uncross-linked recombinant resilin and cross-linked recombinant resilin clearly shows the presence of dityrosine in the cross-linked sample (Figure 9.3c). Further evidence of the presence of dityrosine was obtained by UV irradiation (Xmax,ex 315 nm Xmax,em 409 nm). Dityrosine endows natural resilin with pH-dependent blue fluorescence [38] on UV irradiation. The cross-linked recombinant resilin material was similarly fluorescent, strongly suggesting dityrosine cross-links. 

A dansyl-containing lysine analogue, monodansylcadaverine (MDC), was used in initial TGase linking, because the dansyl UV absorption peak allowed quantification by reverse-phase HPLC using the absorbance at 280 nm. The reacted Qll was dissolved in TFA along with a known dansyl standard. Peak areas of the standard were then compared with product to establish the amormt of MDC present into Qll. Six Qll peaks were measured and ascribed to Qll with zero to five MDCs attached (Fig. 33). 

COWARD L, KIRK M, ALBIN N and BARNES s (1996) Analysis of plasma isoflavones by reversed-phase HPLC-multiple reaction ion monitoring-mass spectrometry. Clin Chim Acta. 247 (1-2) 121-42. 

A variety of mobile phases have been employed for carotenoid separation by reversed phase HPLC. Most are based on MeOH or acetonitrile, with the addition of CH2CI2, THF, methyl-tert-butyl ether (MTBE), acetone, or EtOAc. In general, recoveries of carotenoids are higher with methanol-based systems compared to acetonitrile-based ones." ... 

Although some normal phase methods have been used, the majority of carotenoid separations reported in the literature were carried out by reversed phase HPLC. Among the Cjg columns employed for determination of complete carotenoid compositions in foods, the polymeric Vydac brand is preferably used for separation of cis isomers. Several examples of different C,g columns and mobile phases are cited in the literature, but not aU carotenoids are baseline separated in most systems. Table 6.2.1 shows some examples employing different brands of Cjg columns." Acetonitrile did not improve selectivity toward separation of carotene isomers in a Vydac 201TP column and resolution was strongly dependent on the Vydac column lot. ... 

Minguez-Mosquera, M.I. and FIomero-Mendez, D., Separation and quantification of the carotenoid pigments in red peppers, paprika and oleoresin by reversed phase HPLC, J. Agric. Food Chem., 41, 1616, 1993. 

Addition of 4-nitrophenyl (3-D-glucopyranoside to a solution of the 20 kinds of primary alcohols dissolved in phosphate buffer (pH 5) containing (3-glucosidase was carried out over a period of 16-32 h. The reaction can be easily monitored by reverse-phase HPLC and terminated when the formation of the desired product is at a maximum. The results are summarized in Table 1. 

The peptides were separated by reverse-phase HPLC. N-terminus (N-ter) was obtained with the entire PEy. ... 

Gagliardi, L., De Orsi, D Manna, L, Tonelli, D. Simultaneous determination of antioxidants and preservatives in cosmetics and pharmaceutical preparations by reversed phase HPLC./. Liquid Chromatogr. Rel. Technol. 1997, 20, 1979-1808. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Acetochlor and its metabolites are extracted from plant and animal materials with aqueous acetonitrile. After filtration and evaporation of the solvent, the extracted residue is hydrolyzed with base, and the hydrolysis products, EMA and HEMA (Figure 1), are steam distilled into dilute acid. The distillate is adjusted to a basic pH, and EMA and HEMA are extracted with dichloromethane. EMA and HEMA are partitioned into aqueous-methanolic HCl solution. Following separation from dichloromethane, additional methanol is added, and HEMA is converted to methylated HEMA (MEMA) over 12 h. The pH of the sample solution is adjusted to the range of the HPLC mobile phase, and EMA and MEMA are separated by reversed phase HPLC and quantitated using electrochemical detection. 

The analytes, EMA and MEMA, are separated and quantitated by reversed phase HPLC/OECD. Details of the operating conditions are as follows ... 

The purified sample extracts are concentrated and analyzed by reversed-phase HPLC with fluorescence, MS, or MS/MS detection as described in Sections 2.1 and 2.2. 

The reversibility of dA alkylation by QM3 creates both problems and opportunities. For example, an accurate profile of products formed by initial exposure of DNA to QMs may not be easily determined since labile products such as the N1 adduct of dA would not persist through the typical procedures of enzyme digestion and analysis of the subsequent deoxynucleoside products by reverse phase HPLC. Thus, the full extent of DNA alkylation by QMs may be severely underestimated. 

Plasma Add cold acetonitrile, centrifuge, separate supernatant, fractionate by reverse-phase HPLC and TLC GC/MS and PNMR No data No data Weiss etal. 1994... 

Extracts of all matrices were analyzed by reversed-phase HPLC using ultraviolet detection at a wavelength of 266 nm (Soekhoe and Kerstens, 1995). The limit of detection (LOD) was 10 mg/L for all matrices. Recovery was > 90% and "between days" CV of the analytical chemical method was < 10%. 

Trathnigg, B., Kollroser, M.J. (1997). Liquid chromatography of polyethers using universal detectors V. Quantitative aspects in the analysis of low-molecular mass poly(ethylene glycols) and their derivatives by reversed-phase HPLC with an evaporative light scattering detector. J. Chromatogr. A 768, 223-238. 

A wide variety of methodologies have been employed for the analysis of antioxidants in polymers and some standard methods are available. For high-density polyethylene ASTM method D5524 (ASTM International) — Determination of phenolic antioxidants in high-density polyethylene, describes a method whereby the sample is ground to a small particle size and then extracted by refluxing with cyclohexane. The cyclohexane extract is then examined by reverse-phase HPLC with UV detection. 

Part 20 Determination of epichlorohydrin in plastics Extraction of epichlorohydrin with dioxane, followed by microdistillation and derivitization with 9,10-dimethoxyanthracene-2-sulfonic add followed by reverse phase HPLC with fluorescence detection... 

Normal phase silica column Chloroform-methanol-ammonia solution (86.8 12.5 0.7) 254 nm Assay of primaquine and hepatic targeting neoglycoalbumin-primaquine in whole blood and liver of mouse by reversed-phase HPLC. [105]... 

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