Chromatography automated column

Most of the above methods of colunm chromatography have been, or can be, automated. Devices are available for the automated injection of samples to colunms which are useful for analytical evaluation of samples, for 

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This robotic sample preparation and counting technology, together with mechanical improvements in the chemical separation system, has resulted in an automated column chromatography system that can run almost autonomously, whereas several people were required to operate the ARCA II system for a transactinide chemistry experiment. 

Use of Automated Column Chromatography, Isocratic Elution and Differential Refractometry... 

Other possibilities eire automated column chromatography on ion-exchange resins/ high performance liquid chromatography (HPLC), or high resolution two-dimensional thin-layer chromatography (TLC). Purine bases and nucleosides are simultaneously detected. 

The separation of the polysaccharide components utilizes their different solubUities, polar groups, extents of branching, molecular weights, and molecular flexibUities and may be accompUshed batchwise or with easUy automated column techniques such as column or high performance Uquid chromatography. These procedures have been summarized in several reviews (3,141—143). 

Contaminant by-products depend upon process routes to the product, so maximum impurity specifications may vary, eg, for CHA produced by aniline hydrogenation versus that made by cyclohexanol amination. Capillary column chromatography has improved resolution and quantitation of contaminants beyond the more fliUy described packed column methods (61) used historically to define specification standards. Wet chemical titrimetry for water by Kad Eisher or amine number by acid titration have changed Httle except for thein automation. Colorimetric methods remain based on APHA standards. 

J. R K. Huber and G. Lamprecht, Assay of neopterin in serum by means of two-dimensional high-performance liquid chromatography with automated column switching using tliree retention mechanism , 7. Chromatogr. B 666 223-232(1995). 

Section I of this book includes chapters on the principles and practice of PLC. After this introductory Chapter 1, Chapter 2 provides information on efforts undertaken to date in order to establish the theoretical foundations of PLC. With growing availability and popularity of modem computer-aided densitometers, separation results can be obtained in digital form as a series of concentration profiles that can be relatively easily assessed and processed. From these, relevant conclusions can be drawn in exactly the same manner as in automated column chromatographic techniques. Efforts undertaken to build a theoretical foundation of PLC largely consist of adaptation of known strategies (with their validity confirmed in preparative column liquid chromatography) to the working conditions of PLC systems. 

Despite the advances made in high-performance liquid chromatography in recent years, there are still occasionally applications in which conventional column chromatography is employed. These methods lack the sensitivity, resolution and automation of HPLC. They include the determination of urea herbicides in soil, polyaromatic hydrocarbons, carbohydrates, chloroaliphatic compounds and humic and fulvic acids in non-saline sediments. The technique has also been applied in sludge analysis, e.g. aliphatic hydrocarbons and carboxylic acids. 

Derivatization of primary amino acids with o-phthalaldehyde (OPA) is simple and the poor reproducibility due to the instability of the reaction product can be improved by automation and the use of alternative thiols, e.g. ethanthiol in place of the 2-mercaptoethanol originally used. An alternative fluorimetric method using 9-fluoroenylmethylchloroformate (FMOC-CL) requires the removal of excess unreacted reagent prior to column chromatography. This procedure is more difficult to automate fully and results are less reproducible. However, sensitivity is comparable with the OPA method with detection at the low picomole or femtomole level, and it has the added advantage that both primary and secondary amino acids can be determined. 

ViUeneuve, M.S., Anderegg, R.J. Analytical supercritical fluid chromatography using fully automated column and modifier selection valves for the rapid development of chiral separations. J. Chromatogr. A 1998, 826, 217-225. 

Automated, High-Resolution Analyses for the Clinical Laboratory by Liquid Column Chromatography... 

Higher-specificity techniques such as immunoaffinity chromatography have been also found widespread acceptance for the determination of chloramphenicol residues in edible animal products. The first pertinent reports concerned the determination of chloramphenicol residues in swine muscle (60) and milk and eggs (21). Alternative immunoaffinity chromatography procedures were suggested later for exiraction/preconcentration of chloramphenicol residues from swine tissues (50), or for online immunoaffinity extraction for the determination of chloramphenicol in milk and swine muscle by an automated column-switching system (22). 

Liquid chromatography cleanup on a LiChrosorb Diol column has been further proposed for the offline purification of chloramphenicol residues from bovine muscle and eggs (32). An online approach based on reversed-phase principles has also been described for isolation of chloramphenicol residues from swine kidney by an automated column switching system (63). Use of a protein exclusion column (Hisep) has been also suggested in an online trace-enrichment method for the determination of chloramphenicol in animal tissues (52). By employing a column-switching system, all chloramphenicol that eluted from the protein exclusion column was trapped at the entry of a 5 m Supelcosil LC-18 preconcentration column, to be subsequently back-flashed into the analytical column. 

Thin-layer chromatography of amino acid-phenylthiohydantoin derivatives on silica gel plates, (a) Separation is done in a 98 2 mixture of chloroform and ethanol. (b) This is followed by further separation using an 88 2 10 mixture of chloroform, ethanol, and methanol. More sophisticated procedures, using column chromatography, give superior resolution and improved sensitivity. Automated sequencers always use such procedures. A general description of the use of columns is given in chapter 6. 

M. Cavalleri, W. Polhni and L. Colombo, Determination of ramoplanin in human urine by high performance liquid chromatography with automated column switching , J. Chromatogr. 846 185-192 (1999). 

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