ISO 17025 Validation Requirements - "calibration using reference standards or..."

S

sokolasty

Hello

I'm reading chapter "Validation" of ISO 17025 now. One of the proposed method of validation is:
"calibration using reference standards or reference materials".

I don't understand it - well, I get the words, but I don't see the meaning. Can you help?
 

BradM

Leader
Admin
Re: Validation way acc. to 17025: "calibration using reference standards or..."

"calibration using reference standards or reference materials".

I don't understand it - well, I get the words, but I don't see the meaning. Can you help?

I assume you mean the words in quote, in your quote.:) Is that correct?

Basically it means using standards traceable to N.I.S.T. or an equivalent nationally recognized body. They would be higher order standards than the devices you are calibrating within your lab.

The reference materials refers to chemical compositions and such that are not necessarily traceable to a national standard, but when made using a certain process, are "considered" standards.

Did that answer your question?:)
 
Last edited:
S

sokolasty

Thanks Brad, I get your point, but it seems my question was not clear enough.

This is a quote from ISO 17025 (determination of performance is a validation here):

The techniques used for the determination of the performance of a method should be one of, or a combination of, the following:
— calibration using reference standards or reference materials;
— comparison of results achieved with other methods;
— inter-laboratory comparisons;
— systematic assessment of the factors influencing the result;
— assessment of the uncertainty of the results based on scientific
understanding of the theoretical principles of the method and practical
experience.
I don't understand, how can I validate a calibration method by a calibration.
 
Last edited by a moderator:

BradM

Leader
Admin
I don't understand, how can I validate a calibration method by a calibration.

Actually, you pose a very good question. The statement in the standard does appear a bit circular in logic.

This is just kind of my take on this. I would look at why this section is here.

Say you have a request to calibrate a new instrument. You write up a procedure, and start calibrating them. Strangely, you begin to have a high # of failures in the as-found category. Too, the customers begin complaining their instrument does not seem to operate correctly. Where is the problem?

You question the techs, you at the standard, etc. to try to find the issue. Ironically, after spending a lot of time and effort, you realize the procedure was wrong. There were a couple of steps left out that really made a difference.

The intent of the validation requirement quoted is to validate the process.

  • Does it yield the results it should?
  • Have you identified all the variables involved?
  • Does workstation A yield similar results as workstation B?
  • Do days of the week affect the results?

Perform the calibration (with all the data, of course) then send it to another lab (maybe a competitor). Are the results fairly similar? How do their uncertainty compare to yours?

I feel I am rambling:D, so I will stop.:D

Just remember you need to verify the entire process (and document the verification) prior to considering it acceptable for performing calibrations. Once it is verified, all involved will have more confidence in it.:)
 

harry

Trusted Information Resource
There's a simple (pictorial) explanation on using reference material to establish metrological traceability in the attached.
 

Attachments

  • reference material.PDF
    66.5 KB · Views: 296
Last edited:
Top Bottom