Development of Instrument Control Electronics for PLC-based Analytical Instrumentation

Analytical Instrumentation plays a vital role in the production and evaluation of products to be introduced in the market. This instrumentation is used mainly to evaluate the products for the benefit of the people concerned. Quantitative and qualitative analysis of sample matrix is provided by analytical instrumentation. This analysis helps in detecting toxic/essential elements in the field of food, drugs, water and air etc., Inductively coupled plasma mass spectrometer (ICPMS) is a versatile, complex and a very sensitive analytical instrument. ICPMS is used for compositional characterization of materials up to the levels of parts per billion (ppb) and parts per trillion (ppt). For obtaining required high sensitivities, one needs to optimize nearly 30 to 40 process parameters during the analysis/operation of these instruments. Optimization of these parameters has to be carried out in real time environment through a computer and other electronic sub-systems. The use of electronic sub-systems such as Programmable Logic Controllers (PLCs) in ICPMS simplified the design, implementation of interlocks and subsequent optimization of various process parameters. This paper describes the role of PLCs in Mass-spectrometers in general and ICPMS in specific. An Instrument Control Electronics (ICE) module is developed for interfacing vacuum sub-system to ICPMS. The integration aspects of newly developed ICE to the PLC and the advantages of use of PLCs in `ICPMS' System are discussed, at length, in this paper.