Chromatographic carriers temperature

The following table gives the properties of common gas chromatographic carrier gases. These properties are those used most often in designing separation and optimizing detector performance. The density values are determined at CPC and 0.101 MPa (760 torr).1 The thermal conductivity values, X, are determined at 48.9°C (120°F).1 The viscosity values are determined at the temperatures listed and at 0.101 MPa (760 torr).1 The heat capacity (constant pressure) values are determined at 15°C and 0.101 MPa (750 torr).2... 

Vapor-phase oxidatioa of alcohob. Vapor-phase oxidation of alcohols over a variety of metals and metal oxides has been used mainly in the industry. Sheikh and Eadon now report a simple laboratory procedure for oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones. The alcohol vapor and an inert carrier gas (usually hehum) arc passed through a 6-R. column loo.sely packed with cupric oxide wire worms. A vapor-phase chromatograph provides temperature and flow rate control. Yields are generally high, but allylic and homoallylic alcohols give mixtures of products. 

Chromatographic carriers with dual functionality responsive to pH and temperature were prepared by copolymerisation of a temperature-responsive monomer, with monomers bearing ionic groups (Kanazawa and Okano, 2011). Introduction of cationic or anionic groups allows the retention time of analytes to be controlled by manipulating electrostatic and hydro-phobic interactions in the column. pH helps to control the electrostatic... 

A variable-size simplex optimization of a gas chromatographic separation using oven temperature and carrier gas flow rate as factors is described in this experiment. 

Quantitative analysis using the internal standard method. The height and area of chromatographic peaks are affected not only by the amount of sample but also by fluctuations of the carrier gas flow rate, the column and detector temperatures, etc., i.e. by variations of those factors which influence the sensitivity and response of the detector. The effect of such variations can be eliminated by use of the internal standard method in which a known amount of a reference substance is added to the sample to be analysed before injection into the column. The requirements for an effective internal standard (Section 4.5) may be summarised as follows ... 

Gas chromatograph Injection port Temperature Carrier gas Flow rate Column... 

All hydrocarbon phases are susceptible to oxidation reaction with the small guantities of oxygen normally present is the carrier gas, particularly at elevated temperatures, or from adsorption of air during removal of the column from Chromatograph and its subseguent storage [17,23,24]. Oxidatiom... 

Chromatographic system. (Follow the method described in the general procedure <621 >.) The gas chromatograph is equipped with a flame ionization detector and a 1.2 m x 2 mm column packed with 3% phase G32 on support S1A. The injection port, detector, and column temperatures are maintained at about 250, 300, and 250 °C, respectively, and helium is used as the carrier gas, flowing at rate of about 50 mL/min. The relative retention times for cholestane and miconazole nitrate are about 0.44 and 1, respectively. Chromatograph the Standard preparation, and record the peak responses as directed for procedure The resolution, R, between cholestane and miconazole nitrate is not less than 2 and the relative standard deviation of replicate injections is not more than 3%. 

Chromatographic system. The gas chromatograph is equipped with a flamioniza-tion detector and a 2 mm x 1.8 m glass column packed with 10% phase G34 on 80- to 100-mesh support SI A. The column temperature is maintained at about 150 °C, and the injection port and the detector block temperatures are maintained at about 250 °C. Dry helium is used as the carrier gas at a flow rate of about 40 mL/min. Chromatograph the Standard preparation, measure the peak responses, and calculate the ratio, Rs, as directed for procedure the relative retention times are about 0.5 for valproic acid and 1.0 for biphenyl the resolution, R, between valproic acid and biphenyl is not less than 3.0 the relative standard deviation for replicate injections is not more than 2.0%. 

Gas chromatographic analysis indicates that the yield of methyl 3-hydroxybutanoate is 98% column, PEG-20M on Chromosorb WAW (Stainless steel 3 m x 31, Gasukuro Kogyo) column temperature, 120°C injector temperature, 160°C, carrier nitrogen pressure, 1.2 kg/cm tn of methyl 3-oxobutanoate, methyl 3,3-dimethoxybutanoate, and methyl 3-hydroxybutanoate are 31.5, 34.0 and 41.7 min, respectively. 

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