Increasing TKN Sample Determinations Through Automation

Poster Presentation

Prepared by , H. Maccagno

Contact Information:; 831-375-6227


This presentation will be useful for laboratory managers and staff seeking to optimize their response to increased workload demands. We will discuss our laboratories’ process in identifying the problem, reviewing potential solutions, selecting and implementing method changes and reviewing the outcome.

Our laboratory was looking for a way to respond to the increasing number of wastewater samples requiring Total Kjeldahl Nitrogen determination. Our existing procedures made it difficult to meet our typical turnaround time. The digestion and manual distillation required an entire business day to analyze 16 samples with all of the required quality control standards and due to other demands on staff time, the TKN analysis was limited to 2 runs a week at maximum. The existing procedure itself was quite demanding of the analyst’s attention, limiting time that could be spent on other activities. Our lab, MBAS, works with several wastewater treatment plants in the area, and on any given day we might receive twice the number of wastewater samples than we could fit on our existing digestion block. It became an increasingly frustrating experience for the analyst tasked with completing this task in a timely manner.

Over several months, our staff did research by reading approved methods, contacting other laboratories, and equipment vendors. We chose to automate the TKN determination using gas-diffusion and semi-automated colorimetric analysis, coupled with a 40 place digestion unit. We have increased sample output by 200% with a 75% reduction in sample size. A secondary but very important benefit is the new procedure requires much less of the analyst’s time.