Get Empowered: Empower User Question | Tip #234, Limit of Quantitation (LOQ) and Limit of Detection (LOD)

By July 14, 2021


Tip #234 – Empower User Question: Reporting Peaks Below Limit of Quantitation (LOQ) and/or Limit of Detection (LOD) using a Custom Field in Empower

Welcome back to Get Empowered! In the last Empower tip-of-the-week blog for Empower Chromatography Data System, we learned how to add peak names to molecular weight standards when doing GPC (Tip #233).

In this week’s tip, we will answer an Empower user question.

Q: Can Empower report if peaks are below the Limit of Quantitation (LOQ) and/or below the Limit of Detection (LOD) using a Custom Field?

Great question. The answer is YES. I will explain how Empower can report if peaks are below the Limit of Quantitation and/or below the Limit of Detection using a Custom Field. Classically, Limit of Quantitation is defined at a signal-to-noise ratio of 10 and Limit of Detection is defined at a signal-to-noise ratio of 3.

(Please review Tips #82-99 for information on creating Custom Fields.)

Let’s get started.

Step 1

There are ‘Special Values’ which are used in Custom Fields. Using these ‘Special Values’ will either return a calculated value, such as ‘Amount’ or if the calculation results in -60002 then Empower will return the answer ’Not Detected’. In this way, you can get both calculated results together with text results. (figure 1).

Empower

Figure 1

Step 2

Our example could result in 1 of 3 possible outcomes. The portion of the equation in ‘green’ will result in Empower reporting the ‘Calculated Amount’, the portion in ‘red’ will result in Empower reporting ‘Below Detection Limit’ and the portion in ‘orange’ will result in Empower reporting ‘Below Peak Quantitation Limit’ (figure 2).

Empower

Figure 2

Step 3

The peak Custom Field uses Data Type, ‘Real’ and the Boolean expressions are joined using the ‘+’ (figure 3).

Empower

Figure 3

Step 4

The result displays one peak ‘Below Peak Quantitation Limit’ while the other peaks report the ‘Calculated Amount’ (figure 4).

Empower

Figure 4

 

It’s that easy!

Final Note:   You can use either the Pro or QuickStart interface for this tip.

 

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Next week in Empower Tip #235: We will answer another Empower user question about comparing results from projects with different parent projects.

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JOIN US for an Empower: Ask Me Anything Webinar on September 22, 2021

Neil will answer your questions about streamlining your Peak Purity workflow with Empower using the PDA and QDa Mass Detector.

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Categories: Empower Tips