High-performance liquid chromatography switching valves

Fig. 6.1.4 Components of the high-performance liquid chromatography (HPLC) system for oxidized pterins with column switching. The autosampler starts the chromatography software, which controls valves and pumps. Pump 3 is used only for rinsing the precolumn. Details of the three valves and their different positions are explained in Fig. 6.1.5...

Caprioli and Lin first described this method for the characterization of penicillin G in 1990 [19]. A diagram of the microdialysis/cfFAB experimental setup used is shown in Fig. 8. Dialysate was allowed to collect in a 20- dL sampling loop via syringe pump. After collection, the injection valve was switched and a high-performance liquid chromatography pump was used to deliver the microdialysis sample to the mass spectrometer. Mass spectra of penicillin from both a standard and an in vivo microdialysis sample (shown in Fig. 9) compare well. 

Asafu-Adjaye, E.B. Su, S.Y. Shiu, G.K. Switching-valve-filter technique for the direct injection and analysis of drugs in plasma using high-performance liquid chromatography. J.Chromatogr.B, 1994, 652, 35-42... 

The methods employed for the miscible displacement studies were similar to those used in previous experiments (Hu and Brusseau, 1998). We connected a high-performance liquid chromatography (HPLC) pump (Model 301 from Alltech Associates Inc., Deerfield, IL) to the column, and placed a three-way valve in-line to facilitate switching between treatment solutions. Several iodine species (iodide, iodate, and 4-iodoaniline) were used to study transport behavior. We also examined the transport of tritium and bromide, commonly used conservative tracers, so that we could compare their transport behavior with iodine species. For transport experiments of 4-iodoaniline, which is used as a representative refractory organic iodine species, the solution was allowed contact only with glass or stainless steel, to avoid potential interaction of organoiodine with plastics in the column system. Column effluents were collected with an automated fraction collector (Retriever 500, ISCO Inc., Lincoln, NE) for chemical analysis, as described below. 

Little, C.J. Tomkins, D.J. Sthel, O. Frei, R.W. Werkhoven-Goewie, C.E. Applications of a microprocessor-controlled valve-switching unit for automated sample cleanup and trace enrichment in high-performance liquid chromatography. J. Chromatogr. A, 1983, 264, 183-196. 

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