Quantity chromatographic

Other minor metabolites that have in some cases been identified in trace quantities (chromatographically), after degradation in soil, are A-methylaminomethyphosphonic acid 4, glycine 5, A/,Al-dimethylammomethylphosphonic acid 6, and hydroxymethylphos-phonic acid 7 [25]. 

Number of plates/second Pressure Flow rate (mm/min) Time of experiment Equipment Purpose Quantity chromatographed 0.02 Negligible 5-50 Hours to days Simple column and accessories Predominantly preparative mg to kg 5 Upto 8000 psi 600 Minutes to hours Integrated chromatograph Predominantly analytical ng to mg... 

Bromine ttifluoride is commercially available at a minimum purity of 98% (108). Free Br2 is maintained at less than 2%. Other minor impurities are HF and BrF. Free Br2 content estimates are based on color, with material containing less than 0.5% Br2 having a straw color, and ca 2% Br2 an amber-red color. Fluoride content can be obtained by controlled hydrolysis of a sample and standard analysis for fluorine content. Bromine ttifluoride is too high boiling and reactive for gas chromatographic analysis. It is shipped as a Hquid in steel cylinders in quantities of 91 kg or less. The cylinders are fitted with either a valve or plug to faciUtate insertion of a dip tube. Bromine ttifluoride is classified as an oxidizer and poison by DOT. 

More specific methods involve chromatographic separation of the retinoids and carotenoids followed by an appropriate detection method. This subject has been reviewed (57). Typically, hplc techniques are used and are coupled with detection by uv. For the retinoids, fluorescent detection is possible and picogram quantities of retinol in plasma have been measured (58—62). These techniques are particularly powerful for the separation of isomers. Owing to the thermal lability of these compounds, gc methods have also been used but to a lesser extent. Recently, the utiUty of cool-on-column injection methods for these materials has been demonstrated (63). 

Chromatographic separations rely on fundamental differences in the affinity of the components of a mixture for the phases of a chromatographic system. Thus chromatographic parameters contain information on the fundamental quantities describing these interactions and these parameters may be used to deduce stabiUty constants, vapor pressures, and other thermodynamic data appropriate to the processes occurring in the chromatograph. 

Development of the Chromatogram. The term development describes the process of performing a chromatographic separation. There are several ways in which separation may be made to occur, eg, frontal, displacement, and elution chromatography. Frontal chromatography uses a large quantity of sample and is usually unsuited to analytical procedures. In displacement and elution chromatography, much smaller amounts of material are used. 

Passed at least twice through a gas chromatographic column for small quantities, or fractionally distd under reduced pressure. 

Repeated chromatography on neutral alumina yields minor quantities of solid samples of C76, Cg4, C90 and C94 believed to be higher fullerenes. A stable oxide C70O has been identified. Chromatographic procedures for the separation of these compounds are reported. [Science 2S2 548 7997.]... 

These policy decisions by the FDA were the driving force for chiral switches and the commercial development of chromatographic processes such as simulated moving bed (SMB) technology. Due to technological advances such as SMB and the commercial availability of CSPs in bulk quantities for process-scale purification of enantiopure drugs, the production of many single enantiomers now exists on a commercial scale. 

The distribution coefficient can be determined by batch experiments in which a small known quantity of resin is shaken with a solution containing a known concentration of the solute, followed by analysis of the two phases after equilibrium has been attained. The separation factor, a, is used as a measure of the chromatographic separation possible and is given by the equation,... 

A solution of a 4-azidoquinoline (0.5-0.6 g) and NaOMe (0.3 0.35 g, large excess) in a mixture of MeOH (75 mL) and dioxane (75 mL) was irradiated for 20-30 min with a 400-W high-pressure Hg lamp under N2. A further quantity of NaOMe (1.0-2.0 g) was added and the solution stirred at 20 C for 7-8 h and then concentrated in vacuo. The residue was treated with ice-water (30 mL) and the mixture was extracted with Et20. The extract was washed with sat. brine, dried and evaporated under reduced pressure. The residue was chromatographed (silica gel, Et20) to give the 3//-1,4-benzodiazepine as a yellow oil. 

Please remember that even though we are using the vocabulary of spectroscopy, the concepts discussed here apply to any system where we can measure a quantity, A, that is proportional to some property, C, of our sample. For example, A could be the area of a chromatographic peak or the intensity of an elemental emission line, and C could be the concentration of a component in the sample. 

The colorimetric procedure has been applied to each of the fractions isolated from the partition column. The response to the color test has allowed an accurate prediction of the general type of infrared spectra ultimately found. The color test has also been applied to fractions collected from the gas chromatograph. Of the major responses observed when the pyrethrum mixture is passed through the chromatograph, three of the components respond to the color test. At least two other pyrethrin-like compounds of long retention and small quantity also give the color test. No infrared data are available on these. 

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