Sampling strategies exploiting multi-pumping flow systems.
In this work new strategies were exploited to implement multi-pumping flow systems relying on the utilisation of multiple devices that act simultaneously as sample-insertion, reagent-introduction, and solution-propelling units. The solenoid micro-pumps that were initially used as the only active elements of multi-pumping systems, and which were able to produce pulses of 3 to 25 microL, were replaced by syringe pumps with the aim of producing pulses between 1 and 4 microL. The performance of the developed flow system was assessed by using distinct sample-insertion strategies like single sample volume, merging zones, and binary sampling in the spectrophotometric determination of isoniazid in pharmaceutical formulations upon reaction with 1,2-naphthoquinone-4-sulfonate, in alkaline medium. The results obtained showed that enhanced sample/reagent mixing could be obtained with binary sampling and by using a 1 microL per step pump, even in limited dispersion conditions. Moreover, syringe pumps produce very reproducible flowing streams and are easily manipulated and controlled by a computer program, which is greatly simplified since they are the only active manifold component. Linear calibration plots up to 18.0 microg mL(-1), with a relative standard deviation of less than 1.48% (n=10) and a throughput of about 20 samples per hour, were obtained.
CEQUP/Departamento de Química-Física, Faculdade de Farmácia da Universidade do Porto, Rua Aníbal Cunha 164, 4050, Porto, Portugal.
João A V
JA
Prior
João L M
JL
Santos
José L F C
JL
Lima
D000995:Antitubercular Agents / Q000032:analysis*; D002138:Calibration; D006863:Hydrogen-Ion Concentration; D007538:Isoniazid / Q000032:analysis*; D013053:Spectrophotometry / Q000295:instrumentation* / Q000379:methods*; D013607:Tablets / Q000737:chemistry
D000995:Antitubercular Agents; D013607:Tablets; D007538:Isoniazid