ABSTRACT
The first chromatography detector ever to be used was an LC detector and it was the human eye. Tswett in his pioneering chromatographic separation of plant pigments used the eye to determine the nature of the separation he achieved and even today, as one of the more widespread separation techniques is thin-layer chromatography, the human eye is still one of the more frequently used detectors. The human eye as an LC detector has, however, some severe limitations. The majority of substances that are chromatographed are colorless and thus must be chemically changed to render them visible; furthermore, the retinic response of the eye is not linear, which makes the eye a poor detecting system for quantitative estimation. The human eye, in fact, can only be used for quantitative work as a null sensing device where closely similar light intensities are being matched as in the use of a comparator.
