A low-cost gradient system for high-performance liquid chromatography : Quantitation of complex pharmaceutical raw materials

✍ Scribed by F. Erni; R.W. Frei; W. Lindner

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 655 KB
• Volume: 125
• Category: Article
• ISSN: 1873-3778
• DOI: 10.1016/s0021-9673(00)93824-x

✦ Synopsis

A device is described that makes use of an eight-port motor valve to generate step gradients tin the low-pressure side of a piston pump with a Low dead volume. Such a gradient device with an automatic control unit, which also permits repetition of previous steps, can be .buiEt for about half the cost of a gradie& system with two pumps.

Applications of this gradient unit to the separation of compIex mixtures of giycosides and atkaloids are discuss&and compared with separations with commercial. _mdient systems using two high-pressure pumps. The gridients that are used on reversed-phase mat&at with solvent mixtures of water and completely miscible organic solvents are suitable for quantitative routine control of pharmaceutical products. me reproducibiiity of reTe:ntion data is excelient over several months and, with the use of loop iirjectors, major components can be determined quantitatively with a reproducibility of better tharn 2 % (relafive standard deviation).

The step gradient selector valve can also be used as an introduction system for very itige sample vofumes. Up to 11 can be injected and samples with concentrations of less than I-ppb can be determined with good reproducibilities.

KNTROEXJCFION

Gradient dution techniques in liquid chromatography are of prime importance &r the se&ration-of complex &tires with widely varying polarities. A review on gtadient rzlrrriora systems _fog high-performance @id -chromato_mphy (HW_.C) was ptibfished by Yyeeting'. Most commercial gradient systems generate the gradient on tEt~._&g&p%ss side, w&h requirti two high-qrr&y pumps. Less costly devices -& p&.sibte wth the generation of the gradient on the few-pressure (atmospheric .preSsUre> side.