The D-500 Amino Acid Analyzer was designed and built by Durrum Instruments in the late 1960s. It was used by many prestigious universities and research facilities to test for presence and quantity of amino acids in biological samples. At that time, Durrum was located on Fabian Way, Palo Alto, California, which was the birthplace of many high-tech companies. The D-500 operates using ion exchange chromatography.