Interfacing of spectrophotometric detector to a personal computer via an audio card for a flow injection system

This work describes the use of an audio card for interfacing a spectrophotometer with a personal computer (PC). Digital recording on the computer was carried out using a voltage-controlled oscillator (VCO) and an audio card primarily installed in a multimedia PC. The output voltage of the spectrophotometer was transformed to frequency by the VCO. The audio card, linked to the VCO, converts the VCO output to digital data. An executable program named SigREC was written in C language using Microsoft Visual C++ 5.0 compiler to record the data. The interfacing system was tested and compared with a chart recorder to record signals from a flow injection system with a spectrophotometer as a detector. The audio card system gave a better recording precision (RSD = 1.8%) when compared to the chart recorder (RSD = 2.5%).