Syringe injection system for measuring non-volatile residue in solvents

Abstract

The concentration of non-volatile residue in a test solvent is determined by generating multiple liquid droplets from a liquid stream including the solvent and ultrapure water. The droplets are dried to form a stream of multiple particles of the non-volatile residue. A supply of ultrapure deionized water is caused to flow continuously toward a non-volatile residue monitor, at a constant fluid flow rate. Upstream of the residue monitor, a syringe is provided for intermittently injecting a test solvent into the fluid stream. In one case, the solvent is injected for several minutes at a constant flow rate substantially less than that of the ultrapure water. A mixing valve, downstream of the point of solvent introduction, causes turbulent flow to thoroughly mix the solvent and water. In an alternative approach, a syringe is used to instantaneously inject solvent in the form of bursts. In this case, flow is laminar rather than turbulent, to maintain the solvent burst separate from the water, while it flows with the water in the fluid stream. In either case, the composite of liquid and solvent is provided to the residue monitor. The monitor output is a particle count. A microprocessor receives the particle count and converts the count to derive values for non-volatile residue concentration in the solvent.