Liquid Chromatographic ( LC ) Analyzers

As with any chromatographic technique, High-pressure liquid chromatography (HPLC) should be used only when one needs to know about the makeup of a process stream in the presence of other components that would interfere with nonchromatographic techniques, such as ultraviolet (UV), Fourier transform infrared (FTIR), and near-infrared (NIR) analysis. The use of HPLC as an on-line analyzer was first reported by Mowery and Roof in 1976. A liquid chromatographic separation occurs by placing the sample into the liquid mobile phase. The mobile phase and dissolved sample are moved through the column by a high-pressure pump. Valve plugging has been observed even with particulate-free samples. The cause was attributed to precipitation of sample components when exposed to the analyzer's mobile phase. The HPLC analyzer contains columns with very small particle-size packing materials and small entrance and exit frits.