Empower Tip: Review Window and the Processing Method

Before we get into the specifics of making calculations involving impurities there is one thing I would like to address. Even though we have defined our peak names and their expected retention times in the processing method, oftentimes our samples have impurity peaks that we did not expect to find, and therefore, those peaks have no names. There is a function in the processing method that will assign names to those unknown peaks. Why would we do that? This gives us the ability to reference those peaks in custom fields and reports as well as group them together.

Let’s begin by looking at a chromatogram with an active peak, some identified impurities and a bunch of unknown impurities that have no names.

Click the processing method tool and select the components tab.

Just above the table there is a function called RT Reference Used to Name Unnamed Peaks by RRT. RRT stands for relative retention time. Simply pick a named peak from the list and any unnamed peaks will be assigned a name beginning with RRT followed by a number. That number is the retention time of the unnamed peak divided by the retention time of the selected named peak. In this case I am going to select Active from the list.

Return to the main window and click the quantitate tool. Now the unnamed peaks have names beginning with RRT followed by the relative retention time.

It’s that easy!