The Fusion Total Organic Carbon (TOC) analyzer is equipped with TOC Teklink, a fully optimized graphical user interface.
This blog will demonstrate how Teklink helps to achieve the maximum analytical range for analysis.
To allow for quick startup, predetermined methodology has been set up for various sample types. For example, there are preset methods for analyzing pharmaceutical water, drinking water, and wastewater.
Within each method there is an optimal sample range that states the ideal analytical range for the method. The optimal sample range is the range that works best for each preset method. However, this is not the maximum analytical range of each method. The optimal sample range readout on the computer screen changes according to how much sample volume is used and what dilution factor is selected. There is a universal factor across all methods that is used to calculate the optimal range that is displayed within the method as the parameters are changed.
Let’s look at each of the preset methods mentioned previously for TOC analysis, starting with the pharmaceutical water method. This method is preset to analyze a sample size that is 9.0 milliliters. The optimal sample range for this configuration has an upper value of 6.7 ppm (as seen in figure 1).
Figure 1 - Optimal Range within Method
This upper value for optimal sample range is not a limit, but a guideline. Through experimentation, the actual upper limit was found to be 10.0 ppm. The calibration is shown in figure 2.
The upper limit is determined, first, by Abs counts received from the Non-Dispersive Infrared (NDIR) detector. The highest concentration standard cannot exceed 1000 Abs counts, which is the limit of the NDIR detector. If the Abs counts exceed 1000, an error message will appear stating that the detector has been over-ranged. Over-ranging the detector does not cause any damage to the detector. Performing a cleaning procedure after an over-range will clean the system and prevent any carry-over.
Another factor that determines the maximum analytical range for each method is linearity. As seen in the previous example with the pharmaceutical water method, the upper limit of the calibration curve was increased from 6.7 ppm to 10.0 ppm and the coefficient of determination (r2) is still at an acceptable level of 0.99940.
The next method we’ll look at is the drinking water method, which is preset to analyze 6.0 milliliter volume samples. The optimal sample range upper value is 10.0 ppm. Without changing any parameters, the maximum upper limit has been found to be 20.0ppm.
The final method for finding maximum analytical range is the wastewater method. This method uses 4.0 milliliters of sample along with an automatic dilution for each sample at a 1:2 ratio. This configuration sets the guideline for the optimal sample range upper value at 30.1 ppm. Once again, the actual maximum upper limit has been proven to be higher. A calibration with the wastewater method was successfully performed with an upper limit of 50.0 ppm.
The optimal sample range guideline for each method allows for quick startup and ensures the detector will not be over-ranged. However, knowledge of the maximum analytical range is helpful to enable calibrating to a higher upper limit, which increases the capacity for analyzing samples of unknown concentration. Also, keep in mind, the Fusion TOC Teklink features Intellidilution. This feature can be selected within a schedule to automatically detect an over-range sample. When an over-range sample is detected, the Fusion will automatically run a cleaning procedure and then dilute the sample to within the calibrated range of the method without interrupting the schedule.
Optimizing methods and using features such as Intellidilution enable laboratories to increase productivity and complete sample schedules expeditiously. The Fusion’s many features and method capabilities make it the right choice for a TOC analyzer, one that is designed to provide superior performance for a wide variety of applications.
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