AN INVESTIGATION OF INTERNAL-PRESSURES IN CAPILLARY-FLOW INJECTION SYSTEMS

Results of an investigation of pressure drops in a capillary flow inje ction (CFI) system are presented. Peristaltic and syringe pumps were u sed to drive reagents through a manifold employing fused silica capill aries (75 mu m i.d.) as the reactor tubing. A comparison of pressure c apabilities, baseline noise levels and reproducibility was performed. The maximum stable pressure for the peristaltic pump and syringe pump were 7.6 and 19.2 bar, respectively. The maximum stable pressures for the syringe pump varies with the inside diameter of the syringe. For t he peristaltic pump, the percent relative standard deviation of the pr essure drop was less than 2%. When no time was allowed for equilibrati on, the reproducibility of the syringe pump was between 6% and 10%. Wh en equilibration time was allowed, however the reproducibility was als o better than 2%. Reproducibility was also measured by using an enzyme catalyzed reaction with reaction periods as long as 242+/-1 s. Each p ump showed baseline noise levels of less than 5 milliabsorbance units. Based on these observed values, practical considerations for designin g CFI manifolds are also reported. (C) 1998 Elsevier Science B.V.