Detector minimum detectable level relative

Plots of phase angle difference in the interferometer arms vs. time are related to heat-production vs. time, and this in turn is related to the concentration of the species responsible for heat production. Typical instrument output for the urea/urease system is shown in Figure 3. Calibration curves can be constructed as shown in Figure The system is quite stable, and reasonably sensitive. Minimum detectable levels of urea are 5 mM, compared to the 0.1-5 mM limits for traditional detectors. Over extended time periods (7 days) the relative standard deviation at 5 mM concentrations is better than 5 /.. The optimum FIA conditions were around 1.0 ml/min flow rate, with a sample loop of 0.1-0.25 ml. 

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