High-performance liquid chromatography HPLC continued

Nitrobenzene oxidation was carried out by adding 50 mg of dry soda lignin into a mixture of 7 mL of 2 M NaOH and 4 ttiL of nitrobenzene in a 15 ttiL steel autoclave. Then, the antoclave was heated to 165°C for 3 hours in a preheated thermostat oil bath. After the autoclave was cooled to room temperature, the mixture was then transferred to a liqnid-hquid extractor for continuous extraction with chloroform (5 x 20 mL) in order to remove any nitrobenzene reduction product and excess nitrobenzene. The oxidation mixtnre was then acidified by concentrated HCl to pH 3 and further extracted with chloroform (5x15 mL). The solvent from the second chloroform solution was then removed using a rotary evaporator at 40°C under reduced pressure in order to obtain the nitrobenzene oxidation mixture. The mixture was then dissolved into dicloromethane and made up to 10 luL. This mixture was then used as a stock solution for high performance liquid chromatography (HPLC) analysis [6]. 

The fact that the ionization occurs at atmospheric pressure in a continuous fashion, coupled with the high sensitivity of the technique, enables interfacing the mass spectrometer to column-based purification systems such as high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE).10,11... 

Liquid-liquid partitioning is a convenient and often economical method for bioseparations. L. Gu (personal communication, 1999) has shown that an acetonitrile-water system can be used for separation of proteins. This system partitions into two phases under subzero temperatures with the top phase containing more acetonitrile and water. The low temperature and the presence of water in both phases help reduce protein denaturation. An added advantage is that sample solution can be directly applied to reversed-phase high-performance liquid chromatography (HPLC) for further purification. Aqueous liquid-liquid partitioning is likely to remain an attractive choice for the separation of proteins, and exploration of new systems will continue. 

Since the commencement of this serial publication high-performance liquid chromatography (HPLC) has continued its meteoric growth, and HPLC is now safely entrenched as the premier analytical technique for mixtures of nonvolatile substances. During the past three years the acceptance of HPLC in the life sciences and the expansion of its scope to the rapid separation of biopolymers has been perhaps the most momentous event. The exploitation of the potential of reversed-phase chromatography (RPC) with hydrocarbonaceous bonded phases as a versatile, efficient, and convenient technique is particularly noteworthy in this regard. As it stands now, HPLC has become an indispensable tool in the armamentarium of life scientists and has found wide use on a quotidian basis. 

Displacement thin-layer chromatography (D-TLC) also stemmed from the activity of Horvath s group at Yale University. Experimental work with D-TLC has proven the validity of the rules of displacement chromatography, found by using high-performance liquid chromatography (HPLC). Kalasz et al. continued the research on D-TLC, mainly with the separation of steroids. 

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