An older amino acid analyzer was easily modified with commercially available components to update it by providing more convenient sample application, more accurate timing, greater sensitivity, and automatic regeneration. New features were introduced to permit the optional use of different buffer systems and methodologies as well as the convenient analysis of unusual basic amino acids.
When a single amino acid analyzer is available in a laboratory engaged in several different projects, it is desirable to have flexibility in the choice of analytical systems to be used. For the most accurate analyses, the standard two-column method (1) is preferred. For the analysis of many peptides during sequence determination, an accelerated method provides better utilization of the analyzer. When the amount of sample is limited, a single-column method offers economy. For unusual amino acids, additional buffers are sometimes needed.
In this paper, we describe several modifications of a Beckman 120B amino acid analyzer. The objectives of the changes have been to improve the operation of this older instrument as well as to permit convenient optional use of different buffer systems. Commercially available components have been used.
DESCRIPTION OF THE MODIFIED ANALYZER
Basic instrument. We st.arted with a standard 120B amino acid analyzer (Beckman Instruments, Spinco Division, Palo Alto, CA) equipped with an integrator [Infotronics Corp. (now Columbia Scientific Industries Corp.), Austin, TX]. There were several limitations in this instrument: manual sample application and manual regeneration were required, the timers could not be set accurately enough for a 2-hr run, and the seneitivity was low. Sample app2icntor.s. The short and long columns have been fitted wit,h single sample applicators (items A and B, Table l), as shown in Figs. 1