Personal computer-based visible spectrophotometer design

Background It is possible to see a number of spectrophotometers produced by commercial purposes developed in line with the technical advices identified by the International Commission on Illumination (CIE) in universities' chemistry labs. These devices are employed in measuring and testing materials with unidentified characteristics as well as reporting the results. However, these systems are not modular in design and do not allow updates or modifications. Moreover, when the literature is reviewed, it can be seen that the researches on computer-controlled devices is limited. It is also reported that the devices with user interfaces bring advantages to researchers in terms of time efficiency and safety. Methods In this study, a computer-controlled, modular and low-cost spectrophotometer is designed to measure material densities contained within liquid samples. The proposed system is composed of a main unit, a data acquisition unit and a user interface. All tasks and relevant arrangements involved in a spectrophotometer application are controlled through an interface developed on LabVIEW graphical development platform; the results of the measurements can be monitored in real time, and it is also possible to store data. Thanks to the modular design, it became possible to change and update the relevant stage as needed. The waveform filter can be selected specifically as visible range, ultraviolet range or both depending on the application. Results The experiment was conducted in the visible range and a waveform filter between 400 and 700 nm was used. In the experiments, an easily accessible materials-methylene blue and copper sulfate solutions-were preferred as samples. For these solutions, the waveforms that give the best absorption values were identified and the density was measured at those values. Furthermore, the nonlinearity and repeatability characteristics of the proposed spectrophotometer were analyzed. For this purpose, measured values were compared with the acquired values from another commercial instrument that is already used in medical field. Measurements were repeated 50 times for copper sulfate and 43 times for methylene blue solutions. Conclusions After statistical analysis, it was observed that the reliability of the proposed system is high.