Automated methods online monitoring

Papadopouluo-Mourkidou E. et al., 2001. Use of an automated online SPE-HPLC method to monitor caffeine and selected aniline and phenol compounds in aquatic systems of Macedonia-Thrace, Greece. Frese-nius J Anal Chem 371 491. 

The various methods for the online monitoring of coal composition include the TG technique, which automatically performs a multistep analytical sequence by sequentially drying, burning, and weighing the residue. Figure 3.12 shows the analysis results from an automated TG system. The elapsed time of the proximate analysis program and cooling of the tube back to load temperature totals 30 minutes. 

Monitoring water pollution in a continuous manner provides more thorough information. Online analyzers are especially valuable in analytical control of many parameters in sewage treatment plants. Thus, parameters such as alkalinity, hardness, pH, COD, NH3, Ca +, C1-, F-, NOs , PO -, SiOf", SO, and various metals can be determined using singlepollutant photometric analyzers. There are also automated methods for dissolved oxygen, conductivity, redox potential, and turbidity. Multipollutant... 

Continuous, or very frequent, automated measurement of individual or groups of toxic compounds or general physico chemical properties, can provide a rapid warning of changed environmental conditions. A few chemical methods (such as the LC SAMOS for polar compounds (Slobodnik et al., 1992)) may even detect the occurrence of high concentrations of specific contaminants of concern at the test site. In situ, online and on-site approaches are described in other chapters of this volume, but as yet, application is restricted by the limited availability of suitable, sufficiently sensitive and selective (bio)sensors and monitors for the analysis of (priority) pollutants that need to be monitored. Once available, they may provide (semi)-qualitative and quantitative information on the occurrence of compounds in the waters. 

The tests utilized to measure these contaminants and degradation by-products include infrared (IR) spectroscopy, electronic particle counting (PC), Karl Fischer titration (KFT), atomic emission spectroscopy (AES) and X-ray fluorescence (XRF) spectroscopy. These methods are available in the form of off-line or at-line benchtop instruments and online/in-line sensors. Most off-line instruments are automated to provide several hundred analyses per day by a single technician. At-line instruments and sensors permit immediate results and diagnostic capabilities. Online sensors can be integrated into machinery control systems to provide real-time monitoring capability. 

---