QC Standards
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So how do we choose reference material? How do you choose what quality control standards you're going to use? Oh, wait…I almost got carried away.
Welcome back to MSM Solutions YouTube Channel. Quality systems. Quality people. Today we discuss the use of QC or reference material, what exactly are these and how do we use them.
So you have a QC. You need to define what do you want the QC to do. You cannot just pick a random QC and think it’s fine.
You have to ask yourself what is this reference material going to do? What concentration level do I need? If the sample you want to analyse is between zero and 10pp will you go and get a QC that is 100ppm?
No, because your QC has to fit with your samples and not just based on concentration levels, but the whole matrix and structure must be as close as possible to your actual unknowns.
There’s no point in analysing a QC that’s a liquid, but your samples are solids because those samples have no comparative data between your QC and your unknowns.
Besides choosing the correct QC, you need to consider stability. You don't want to use a sample today as quality control and then tomorrow you can’t use it because it has a 24-hour shelf life.
The shelf life will help you determine when, how often, and how much of the sample to use before it expires. Also, take note of the storage requirements as incorrect storage can lead to a decreased shelf life.
Another thing to take note of is the uncertainty of the stated confidence limit for that sample. So, if you use it, you're not going to get the same number every time.
You need to know what the uncertainty within the space is. So, you know, what range can you work in. Moving along…we have reference material, but we also have certified reference material and there's a difference between the two.
Reference material is defined as a “material, sufficiently homogeneous and stable with respect to one or more specified properties, which has been established to be fit for its intended use in a measurement process”.
A certified reference material is characterized by a metrologically valid procedure for one or more specified properties, accompanied by a reference material certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability”.
The biggest difference between a reference and a certified is a statement of metrological traceability. And in the next series, we will look broader into the difference. We will discuss what you should look for in certified reference material and what to do with it.
Thank you for watching and see you in the next video.