Refractive-index detection by interferometric backscatter in packed-capillary high-performance liquid chromatography.

A simple, inexpensive, micro-volume refractive index detector has been applied to packed capillary high-performance liquid chromatography. Nanoliter detector volumes produced by a unique optical train, based on interferometric backscatter, allows for universal solute detection at the picogram level. System utility is demonstrated by reversed-phase separation of a test mixture containing ppm levels of NaCl, phenol, ethyl benzene and toluene.

Specific rotation measurements from peak height data, with a Gaussian peak model.

A method is described whereby a sensitive laser-based polarimeter can be used to make very accurate and precise specific rotation measurements on microgram quantities of optically active materials. Flow-injection or liquid chromatography systems provide reproducible introduction of the sample into the polarimetric system. If a Gaussian distribution of the analyte concentration is assumed, the peak height can be used in the determination of specific rotation. This method provides a direct calibration with an absolute standard which yields more accurate and precise results than those obtainable by using peak area.