Daily Balance calibration

[Consumer Products Guy]

The company I work for, in its infinite wisdom, decided in the past to do with very few techs or lower-level scientists. This makes it difficult to justify highly-paid people to do routine stuff like checking balances daily (the manufacturers of the balances, the experts, detail monthly or every two months to check them), washing glassware and putting it away, collecting wastes, safety inspections, etc.

[Dan]

KarenJ,

I just wanted to point out a clarification about the references to the USP Chapters.

USP Chapters numbered <1000> and above are General Information Chapters. To quote the USP itself:

"The chapters in this section are information, and aside from excerpts given herein from Federal Acts and regulations that may be applicable, they contain no standards, tests, assays, nor other mandatory specifications..."

Thus the information given in USP<1251> is for information only and is not a requirement.

Also note that the tolerance of +/- 0.2 mg is a check for drift on analytical balances as given in USP<1251>. I think what you should use is the 0.1% accuracy tolerance for check weights as given in USP<41>; that's what we use for our weight checks.

In our pharmaceutical labs (with strict GMP) we test two check weights, one above and one below the range of weights of our samples. We do this with every use of the balance. We don't call it a "daily weight check" as our QA group would then make us do the weight checks every day even if we aren't using the balance. Sounds crazy but that's life with QA and GMPs.

Regards,
Dan

[HW Mueller]

KarenJ,
+ or -0.2mg on what weight range balance? (Shouldn´t we call them scales to be correct all the way through?)
Anyway, after having made certain we don´t vary more than 0.4mg we then proceed to weigh out a powder to a predetermined weight with + or - 1mg variation?

[HW Mueller]

C P Guy,
lucky that you are not here in Giessen where they eliminate top notch people for misplaced (I mean that they don´t like their job) technicians.
Dan,
your method is almost as good as what we had to use when I startet to study chemistry: Real balances with the weights on one pan, the material on the other. (Now I wish I had one of those things, beautiful, .... some with weight chains instead of weights...anybody remember?)

[rnelson]

I'd have to agree that the critical requirements for balances would be chapter <41>. It seems like a tall order to be able to insure that my check weight used for drift didn't change by more than 2ug from day to day.

Consumer Products Guy - We no longer have techs perform our daily weight checks. We rotate the responsibility between analysts, we decided the daily check was far too critical to have non-degreed folks do it. That's not meant to be a slam on techs, but just to be able to show the FDA that the person performing this important function has proper background knowledge. Besides, if your lab is like mine, even analysts seem to find time to play an occasional computer game, or email friends, or post messages on forums.

Dan - Even though we call ours a "daily" weight check, that doesn't imply it must be done every day. It simply means that every day we use a particular balance, we must perform the weight check first.

KarenJ - Just my two cents, but the end user of your SOP's should be the first line of defense in determining whether your procedures are compliant, and take action to notify QA or the person responsible for updating them.

[KarenJ]

Actually the USP chapter that I am referring to is chapter <1251> Weighing on an Analytical Balance. The section is called Quality Assuance Procedure for Measurement of Balance Drift. It specifies a criterion of +/- 0.2mg (200 ug) for check-weights weighed on analytical balances regardless of the mass you are weighing. I'm not commenting on the scientific validity of this criterion, I'm just stating what it is and where it is stated.

This chapter also gives guidance for how to weigh samples which I've noticed has also been a topic in this forum.

KarenJ

[ajaib5]

Dear Dan,
Most of the USFDA guidelines have mentioned 'These are general recommendations only and u can follow any other scientifically justified procedure; . So r we not using them?
If u read and to other query as the link given by unmgvar to USFDA ans
'The frequency of performance checks depends on the frequency of use of the scale and the criticality and tolerance of the process or analytical step. Note that all batches of a product manufactured between two successive verifications would be affected should the check of the auto-calibrator reveal a problem'. So how u will define critical step in pharma operation esp in Analytical Lb, all the weighings will be critical, whether u are doing it for reagent or standard or sample preparation.
I think if u perform the weight check during the sample weighing, will be more laborious as compared to daily check.

[JI2002]

Other than temp, humidity, pressure and air flow all affect balance. No matter what the regulators and auditors say, it's just a good practice to check the balance daily.