Date of Award


Document Type

Union College Only

Degree Name

Bachelor of Science






In this paper we discuss the interface of a liquid chromatograph with an· Apple II+ microcomputer, The system consists of a Varian 5000 High Performance Liquid Chromatograph (HPLC), a Tracor 970A variable wavelength absorption detector (VWD), an Apple II+ computer, and an interface unit which consists of an operational amplifier and a Mountain Computer A/D + D/A converter. The op. amp. modifies the output signal of the VWD (0 to +lV) to meet the input specifications of the A/D converter (-5V to +5V). This allows the conversion of the continuous analog signal from the VWD to a digital signal, which is required by the Apple. The system produces chromatograms (digital absorption equivalent value vs. time) using the high resolution graphics screen of the Apple, which can be printed with an Epson dot matrix printer. Further, it calculates retention times, performs peak integration, and prints out the results from these operations. A comparison of the Apple's integration with standard cut-and-weigh as well as triangle approximation methods gives an indication of the reliability of the integration technique. A manual, which requires that the user have only minimal computer experience, has been written to facilitate user access to the system.