Ion Exchange Chromatography of Amino Acids

This paper will briefly describe an apparatus for the determination of amino acids by ion exchange chromatography. The procedure has a reasonable claim to being automatic, but like all other procedures thus far deit fails to go beyond analogue presentation of data. Data processing to the point of yielding useful digital records has still to be accomplished. Some tentative steps in that direction are, however, indicated. This paper also describes the determination of amino acids in pg. amounts, and methodology is indicated whereby the free amino acids in 0.1 ml. of serum or plasma can be determined. With small quantities of amino acids, an advantage is gained in that the Beer-Lambert law, though logarithmic in form, may be treated linearly for absorbence changes from 0 to approximately 0.04. Accepting this restriction, it becomes unnecessary to convert photometric output voltages to their logarithm in order to display peaks whose ordinates (and areas) are directly proportional to the amount of amino acid placed on the column. This advantage is unfortunately partially offset when amplification is employed to display the amino acid peaks over a reasonable proportion of the recorder scale; base-line change and variability (lumped together and referred to as column noise) also became amplified. A partial solution to this difficulty has been found in the design of a split-beam photometer, operated in a manner that provides self-compensation. Some exploratory work with this photometer will be described.