The quantitative estimation of substances on paper chromatograms : I. A machine for the treatment of paper strips with chemical reagents

Abstract

A machine is described for the reproducible treatment of paper chromatograms with liquid chemical reagents. Strips of filter paper 5 cm wide are passed through the machine by two pairs of belts which grip the edges of the strip leaving the central area exposed on both sides. A film of liquid reagent is fed on to the undersurface of the paper strip by means of a roller and trough which is fed from a simple constant level device. The reagent-soaked strips pass immediately into a straight tunnel into which a stream of hot air is introduced by ports opening from manifolds running along the sides of the tunnel. The air stream is passed out of the top of the tunnel by means of an exhaust tube and fan connected to its distal end. The strips are passed out of the machine by disengagement of the belts which are returned to the starting point of the machine after being washed, and dried on their return passage through the hot air tunnel. Operating temperatures up to 150° can be achieved and are adequate for producing quantitative and complete reactions with the majority of color reagents that are useful for the quantitative estimation of substances by direct scanning of paper chromatograms ( e.g. Zimmerman reagent, ninhydrin, phosphomolybdic acid). The mechanization of the treatment of paper chromatograms with color reagents improves greatly the reproducibility of the results, the evenness and reproducibility of background, and enables the successful use of color reactions which cannot be controlled sufficiently by manual methods to allow their quantitative estimation. It also enables the treatment of very large numbers of chromatograms: the present apparatus is capable of treating 40 cm long chromatograms at a rate of up to 88 per h or over 500 per day. The development, important features of design, and method of operation of the machine are described.