LCGC North America-01-01-2005

Reagent water is used in all aspects of liquid chromatography (LC) technology, from preparation of mobile phase to preparation of standards, blanks, and samples. Reagent water is the most widely used analytical solvent, yet it is the least characterized, especially in total organic carbon (TOC) content. TOC adversely effects performance of LC methods and hence, reagent water quality is a major issue. Organics initially present in tap water will be reduced efficiently to low parts-per-billion concentrations by combining several technologies embedded in a water purification system. Monitoring the TOC concentrations gives chromatographers added confidence in their results.

In last month's installment of "GC Connections," John Hinshaw discussed how peak retention times depend upon relationships between pressure, flow rate, oven temperature, column dimensions, and stationary phase. This concluding installment of a two-part series discusses the effects that column variability has on isothermal capillary gas chromatography and explores instrument calibration with the goal of maximizing instrument-to-instrument similarity of retention times.

The effects of temperature on HPLC are explored, along with a critical analysis of the effects of temperature change on both peak shape and efficiency.