Hexane High-performance liquid chromatography

For the high-performance liquid chromatography (HPLC) determination of napro-anilide and its metabolite, 200 mL of 2% sodium sulfate in 0.1M potassium hydroxide solution are added to the concentrate derived from Section 2.2.2. The solution is shaken twice with 100 mL each of dichloromethane or ethyl acetate-n-hexane (1 1, v/v) for 10 min. The combined organic layer is concentrated. " ... 

Distilled water, high-performance liquid chromatography grade Acetone, ethyl acetate, diethyl ether, acetonitrile, n-hexane, benzene, pesticide residue analysis grade... 

High-performance liquid chromatography (HPLC) with a micellar mobile phase or with a selective pre-column or reaction detection system has also been used to determine alkylenebis(dithiocarbamaes). ° Zineb and mancozeb residues in feed were determined by ion-pair HPLC with ultraviolet (UV) detection at 272 nm. These compounds were converted to water-soluble sodium salts with ethylenediaminetetra-acetic acid (EDTA) and sodium hydroxide. The extracts were ion-pair methylated with tetrabuthylammonium hydrogensulfate (ion-pair reagent) in a chloroform-hexane solvent mixture at pH 6.5-8.S. The use of an electrochemical detector has also been reported. ... 

Plant materials are homogenized with methanol. Hexythiazox residue is extracted with hexane and then transferred to acetonitirile by liquid-liquid partitioning. The acetonitirile is removed by rotary evaporation and the sample is cleaned up using Florisil PR column chromatography. The concentrated eluate is subjected to high-performance liquid chromatography (HPLC) analysis. 

Pyrimidifen is extracted from plant materials with methanol-water (7 3, v/v). The extracts are concentrated and pyrimidifen is partitioned with n-hexane after addition of sodium chloride. The organic phase is collected and concentrated. Pyrimidifen in the organic phase is purified by silica gel column chromatography. Pyrimidifen is dissolved in acetonitrile and injected into a high-performance liquid chromatography... 

Methanol, n-hexane, ethyl acetate, distilled water, sodium chloride, sodium sulfate, reagent grade for residue analysis (Wako Pure Chemical Industries, Ltd, Japan) Acetonitrile, methanol, distilled water, reagent grade for high-performance liquid chromatography... 

Enantiomers of the 8,9-dichloro-2,3,4,4 ,5,6-hexahydro-177-pyrazino[l,2-tf]quinoxalin-5-one (structure 249 Rz = R3 = Cl R1 = R4 = H) could be separated by normal-phase, chiral high-performance liquid chromatography (HPLC) with increased retention and separation factors if ethoxynonafluorobutane was used as solvent, instead of -hexane <2001JCH(918)293>. 

Aboul-Enein and Ali [78] compared the chiral resolution of miconazole and two other azole compounds by high performance liquid chromatography using normal-phase amylose chiral stationary phases. The resolution of the enantiomers of ( )-econazole, ( )-miconazole, and (i)-sulconazole was achieved on different normal-phase chiral amylose columns, Chiralpak AD, AS, and AR. The mobile phase used was hexane-isopropanol-diethylamine (400 99 1). The flow rates of the mobile phase used were 0.50 and 1 mL/min. The separation factor (a) values for the resolved enantiomers of econazole, miconazole, and sulconazole in the chiral phases were in the range 1.63-1.04 the resolution factors Rs values varied from 5.68 to 0.32. 

The product was analysed by gas chromatography (GC), dissolved in hexane/propan-2-ol (70/30) and analysed by chiral high-performance liquid chromatography (HPLC)... 

Product ester ee was determined by isocratic normal-phase high-performance liquid chromatography using a Chiralcel OD-H (250 mm x 4.6 mm) column and a 98 % hexanes/2 % isopropanol mobile phase at 1.75 mL min and 25 °C. The undesired (/ )-ester and desired (5)-ester were quantified using their characteristic retention times of 10.3 min and 21 min respectively during elution. 

Chiral analysis for ee determination was by normal-phase high-performance liquid chromatography with a Chiralcel OD-H column using 98 % hexanes/2 % 2-propanol at 1 mL min 25 °C and monitoring at 265 nm. 

Nomeir AA, Abou-Donia MB. 1985. Analysis of n-hexane, 2-hexanone, 2,5-hexanedione, and related chemicals by capillary gas chromatography and high performance liquid chromatography. Anal Biochem 151 381-388. 

A Zorbax-CN high performance liquid chromatography (HPLC) column used with hexane as mobile phase produced desirable results. Details of the HPLC procedure will be published elsewhere (5.). Three HPLC subfractions of S1-C2 were made ... 

Fig. 30 Silver ion high-performance liquid chromatography (Ag-HPLC-FID) with flame ionization detector (FID) analysis of the triacylglycerols of chromatographed Crepis alpina seed oil. Ag-HPLC-FID conditions 0.5-mg sample 5-micron Chromspher Lipids column (Chrompack International, Middelburg, The Netherlands) (4.6 X 250 mm) mobile phase 0.5% acetonitrile in hexane (v/v) flow rate 1.0 ml/min FID. Chromatogram peak triacylglycerol fatty acid abbreviations S, saturated (palmitic and stearic) O, oleic L, linoleic and Cr, crepenynoic fatty acids.

Pretreated samples were evaporated to remove nonreacted methanol and extracted by solvents (chloroformin-hexane = 1 2) and centrifuged at low temperature to remove glycerin. One milliliter of supernatant was evaporated under vacuum and diluted with methanol (high-performance liquid chromatography [HPLC] grade) for HPLC analysis. 

Hullett and Eisenreich [11] used high performance liquid chromatography for the determination of free and bound fatty acids in river water samples. The technique involves sequential liquid-liquid extraction of the water sample by 0.1m hydrochloric acid, benzene-methanol (7 3) and hexane-ether (1 1). The resultant extract was concentrated and the fatty acids were separated as a class on Florasil using an ether-methanol 1 1 and 1 3 elution. Final determination of individual fatty acids was accomplished by forming the chromatophoric phenacyl ester and separating by high performance liquid chromatography. Bound fatty acids were released by base saponification or acid hydrolysis of a water sample from which the fatty acids had been removed by solvent extraction. 

Mori [20] has identified and determined very low levels of phthalate esters in river water using reversed phase high performance liquid chromatography using an ultraviolet detector. Phthalates were extracted with n-hcxanc and the uncleaned or concentrated extracts were injected into three chromatographic systems, these being cross-linked porous beads (Shodex HP-225, Showa Penko Co.), porous polymer beads and polystyrene GPC gel. The eluants were respectively / -hexane (system A) and methanol (system B), and chloroform (system C). 

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