SINGLE-PUMP SOLVENT PROGRAMMER FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING SYNCHRONIZED VALVE SWITCHING

The performance of several commercial high-performance liquid chromatography solvent programmers has been tested for isocratic and gradient elution. Significant differences have been observed between the imposed and the actually delivered composition of the solvent mixture. The deviations can be traced to the principal limitations of the presently available single- or dual-pump programmers. Such shortcomings have been overcome in a single programmer that can be incorporated in any reciprocating piston pump. The design uses a three-way valve switching periodically between two solvents. Because the valve switching is synchronized with each refill stroke of the pump, highly stable, reproducible and accurate binary compositions can be delivered in both isocratic and gradient elution. The principle is easily extended to ternary systems. © 1979.