Computer-controlled Mobile Chemical Analysis Systems and Their Application to Multi-component Analysis in Environmental Samples

Mobile chemical analysis (MCA) systems were examined to improve on-site analysis. The MCAs developed were expected to be superior in rapidity and robustness to batch-wise methods in chemical analysis, as well as being less heavy and battery-driven, and to be able to measure multi-components in a system. Also, the system had better to be simple, and to be able to automate chemical analysis. In this work, the MCA systems were developed on the basis of both of a flow chemical analysis technique and a computer-controlled technique. The essential modules for assembling MCA systems were syringe pump modules, valve modules (switching- and selection-type) and solenoid pumps as well as valves modules. For controlling such pumps and valves, a lab-made software, so-called LMPro, was developed; it could control fifteen syringe pumps and valves, as well as fifteen solenoid pumps and valves. By using this software, almost all computer-controlled flow chemical analysis systems reported so far could be controlled; further, some new MCA systems could be developed by assembling such pump and valve modules. In the present work, several kinds of computer-controlled flow chemical analysis (CC-FCA) systems for MCA were examined by using software, LMPro ver.1-5. The CC-FCA systems assembled and examined were: a syringe-propelling flow injection analysis (SP-FIA) system, an air-walled SP-FIA (AW/SP-FIA) system, a sequential injection analysis (SIA) and SI-related systems, a merging zone-FIA (MZ-FIA) system, a simultaneous injection effective mixing flow analysis (SIEMA) system, a column pretreatment (Auto-Pret) system and so on. Such systems were controlled by the LMPro program without any problems. For multi component analyses, a multi-channel absorptiometric detector with an RGB LED lamp was used. As model analytes, nitrite and nitrate ions, phosphate ion, ammonia and Cr(VI) ion were examined. Of the MCA systems examined, SP-FIA and AW/SP-FIA were favorably applied to a sensitive measurement, because of less Schlieren effect (SE). In SIA, MZ-FIA and SIEMA, SE was relatively large, and sometimes SE interfered with the measurement of low concentrations of analytes. A method for compensating SE was examined by using the similarity of SE between different wavelength.