Chromatography equipment, preparation

In industry and academia the need often arises to isolate portions of a polymer sample, whether it be to separate low molecular weight material from a sample or to actually fractionate the polymer across its molecular weight distribution. If gram quantities of isolated polymer are needed, true preparative chromatography equipment and techniques are usually necessary. 

Liquid-liquid extraction(s), 10 744-800 of aromatics, 25 168 for capillary chromatography sample preparation, 4 609 equipment and processing in,... 

A second field of rapid development in the l.c. of carbohydrates is in practical, preparative chromatography. Early preparative systems used large, expensive columns with low resolving power, and hence, were not extensively applied in carbohydrate research. New research is showing that various carbohydrates can be separated on the gram scale, using normal l.c. equipment and large columns home-packed with relatively... 

Colin, H., Ludemann-Hombourger, O. and Denet, F. (2005) Equipment for preparative and large size enantioselective chromatography, in Preparative Enantioselective Chromatography, 1st edn (ed. G. Cox), Wiley-Blackwell, Hoboken N), pp. 224-252. 

Gas chromatography equipped with a flame ionization detector (FID) and quadrupole MS have been employed for measuring carbon disulfide concentrations in the breath of workers following exposure to carbon disulfide (Campbell et al. 1985 Wells and Koves 1974). The MS technique is rapid and requires no sample preparation (Campbell et al. 1985). A detection limit of 1.6 ppb (5 pg/m3) of... 

A chromatography equipment is quite complex and many technical failures may happen when operating a preparative device. Most of the time, a technical problem is directly visible or even detected by the system if this one is automated. 

Fig. 8. Preparative Anion Exchange Column Chromatography Equipment...

Time, Cost, and Equipment Analysis time can vary from several minutes for samples containing only a few constituents to more than an hour for more complex samples. Preliminary sample preparation may substantially increase the analysis time. Instrumentation for gas chromatography ranges in price from inexpensive (a few thousand dollars) to expensive (more than 50,000). The more expensive models are equipped for capillary columns and include a variety of injection options and more sophisticated detectors, such as a mass spectrometer. Packed columns typically cost 50- 200, and the cost of a capillary column is typically 200- 1000. 

Oligosaccharides were isolated preparatively by high-pH anion exchange chromatography carried out on a LC-system (Dionex Corporation, Sunnyvale CA) equipped with a CarboPac PA-1 column (9 x 250 mm), coupled to a Spectra System AS 3500 auto sampler. The detection was carried out using Pulsed Amperometric Detection (PAD-II). 

As explained in Chapter 1, classical preparative layer chromatography (PLC) involves flow of the mobile phase by capillary action. The method uses relatively basic equipment and is not expensive. 

Multidimensional liquid chromatography encompasses a variety of techniques used for seunple separation, cleanup and trace enrichment [12,279-289]. A characteristic feature of these methods is the use of two or more columns for the separation with either manual or automatic switching by a valve interface of fractions between columns. These techniques require only minor modification to existing equipment, and of equal importance, enable the sample preparation and separation procedures to be completely automated. 

Chromatographic system (See Chromatography <621 >.) The liquid chromatograph is equipped with a 230 nm detector and a 4.6 mm x 30 cm column that contains packing L7. The flow rate is about 2 mL/min. Chromatograph the Resolution solution and the Standard preparation, and record the peak responses as directed under Procedure the resolution, R, between the dibutyl phthalate and miconazole peaks is not less than 5, the tailing factor for the miconazole peak is not more than 1.3, and the relative standard deviation for replicate injections of the Standard preparation is not more than 2%. The relative retention times are about 0.7 for dibutyl phthalate and 1 for miconazole. 

Thin-layer chromatography (TLC) is one of the most popular and widely used separation techniques because of its ease of use, cost-effectiveness, high sensitivity, speed of separation, as well as its capacity to analyze multiple samples simultaneously. It has been applied to many disciplines including biochemistry [1,2], toxicology [3,4], pharmacology [5,6], environmental science [7], food science [8,9], and chemistry [10,11]. TLC can be used for separation, isolation, identification, and quantification of components in a mixture. It can also be utilized on the preparative scale to isolate an individual component. A large variety of TLC equipment is available and discussed later in this chapter. 

The prepared mixtures were placed in the extraction vessel, and stirred for 2 h and then left to settle for 4 h. Samples were taken by a syringe (Gaschromatographic s Hamilton 0.4 p,L) from both the upper (methylcyclohexane) phase and lower layers (aromatic phase). Both phases were analyzed using Konik gas chromatography (GC) equipped with a thermal conductivity detector (TCD) and Shimadzu C-R2AX integrator. A 2 m x 2 mm column was used to separate the components... 

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