Multi-Parameter Analysis and Enhanced Productivity by the Consolidation of Inorganic Wet Chemistry Methods
Robert V. Menegotto, MANTECH
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Multi-tasking and time allocations are key components to running an efficient laboratory and decreasing the cost per analysis for pH, conductivity, alkalinity, chloride, fluoride and ammonia. The cost of analysis has risen over the years while revenue from these parameters has remained the same. Much of the high cost is due to the use of multiple instruments, multiple trained technicians and outmoded automation available. By the development of a single automated system, with computer control, capable of connecting multiple electrochemical sensors (e.g., pH, conductivity and Ion Selective Electrodes – ISE’s), the research showed that the cost of analysis could be significantly reduced by analysing all these parameters from one sample. Analysis costs were reduced by 80% or more depending upon the actual parameters measured and autosampler size used. Important criteria for the success of these analyses included automatic pipetting, titration capability, delta time/delta mV stability variables, non-linear calibration curves, automatic dilution capability and electronically isolated electrode boards. In addition, it was found that the conductivity probe must be separated from all other electrodes, due to reference electrolyte interference from the pH and ISE electrodes. By employing these techniques, the detection limits for each analyte were not affected. For alkalinity and chloride it was 1ppm, for fluoride less than 0.1ppm, for ammonia less than 0.05ppm and for conductivity, values below 2uS were successfully measured. Statistical results for each parameter measured from a single sample cup, over a large concentration range will be presented. Actual cost savings calculations and method details with correlation to approved methods will also be presented.
Multitasking and time allocations are key components to running an efficient laboratory and decreasing the cost per analysis for pH, conductivity, alkalinity, chloride, fluoride and ammonia. As evidenced by a News Release in Ontario, “Harris Government Action Plan to Improve Water Quality Includes Tough New Regulation”¹, both the scope and frequency of testing for these parameters and others continues to increase as governments enact tougher environmental regulations. The cost of analysis has risen over the years while revenue from these parameters has remained unchanged or decreased. To control costs, laboratories in government and industry have instituted hiring freezes, thereby, increasing the workload and responsibility of laboratory chemists. This is not the optimal environment for making informed, confident and legally enforceable analytical decisions. Any automation available for these laboratories would help alleviate the workload and provide increased confidence in data reporting.
For pH, conductivity, alkalinity, chloride, fluoride and ammonia, much of the high cost of analysis is due to the use of multiple instruments, multiple trained technicians and outmoded automation available. These parameters are important since they have well defined standard limits for health and environmental considerations.
This paper describes the development of an automated measurement system for pH, conductivity, alkalinity, chloride, fluoride and ammonia. The experimental results will show that these parameters can be measured in the same system, that approved methods can be followed and that the cost of analysis can be significantly reduced while maintaining confidence in the measurements.