Daily Balance calibration

[ajaib5]

Dear all

What is the requirement for the daily calibration check of the analytical balances for the pharmaceuticals? We were doing internal balance calibration only, recently one auditor suugeted to check the balance calibration daily by using at leat two standard certified weights in the widely used range of the balance say 50 mg 500 mg, in additional to monthly calibration by weights.

I would like to know the industrial practice. Do we need standard certified weights or not?

Please advice

Thanks/Regards

[unmgvar]

unless your balance can not perform an internal calibration there should be no need for you to double check daily the performance of your scales.

from my experience we also only check the scales with certified weights once per month, and repeatability of weight every 6 month. for the daily check we use the internal calibration of the scales. this is more then satisfactory. our SOP's have been through FDA and EP audits, and were not commented on. make sure that your monthly check cover the range of measurements that you perform daly with the scales and that you do not quantitatively weight below or over that range.
for exemple don't check your scale between 10mg to 10 g weihgt but then quantitatively weight 5 mg on that same scale all the time. interpolate don't extrapolate.

[ajaib5]

But the USP has recommended the drif check daily before use in chapter <1251>.

Regards

[unmgvar]

on this page you will find a more official help:

http://www.fda.gov/cder/guidance/cGMPs/lab.htm#1

from my understanding it states that you do not need to proceed with a daily use of STD weight to calibrate your balances.BTW for the monthly check we do use certified weight of class E2. those weight are tested every year for accuracy. every 6 month an in house technician checks the accuracy of the auto calibration as well.

[MK]

we check critical balances on daily basis by using weights from low and upper end of the range. It takes 1 minute and enables you to react immediately when the balance starts to drift. In my experience the upper check is especially important as the drift usually "starts" from there.

[syx]

We, in our lab, perform internal calibration right after the balance turned on, and external calibration every 6 months.

Regards,
Siswanto Tanuatmojo

[ajaib5]

The USP in general chapter <1241> has stated that the balance drift should be checked daily, before start using the balance with a check weight of say 20 gm for the analytical balances.

I know many pharma analytical lab are doing balance calibration daily at least with 2 std wts.

Regards

[KarenJ]

Ajaib,

You are correct that the USP requires a daily check in general chapter <1251>. It is probably safest to write this requirement into your SOPs. Chapter <1251> also states that you should calibrate your balance daily, before doing the weight check and that "...the variation in the observed weight does exceed +/- 0.2 mg" of the mass of the weight you are using for the check . When I set up my SOP, I did 10 consecutive weighings to get an average weight. Then I wrote that the acceptable range is that average +/- 0.2mg. In my yearly OQ, I repeat the 10 weighings to see if the average value is still correct.

KarenJ

[DR]

We do regular calibration checks with very precise, traceable standard masses. Our daily checks are with cheap brass masses as all we are looking for is deviations from the established norms for these masses.

[dwalker]

Hi ALL

We check our analytical balances using class E2 weights EVERY day. I work in a pharm lab

0.1g

2g

20g

100g

i feel it is a little over the top, but then again...

[rnelson]

We actually check several weights daily on every balance.

We have the balances calibrated every 3 months, the daily check is to verify the calibration is still OK.

Our reason for doing this every day is based on risk. If you calibrate every 3 months and never perform a daily check, then a week before your next calibration you run into a problem with the balance, you've just exposed all of your data since the last calibration to investigation. How do you know when the problem started?

Perform a check every day and you limit the scope of investigation to one day.

[HW Mueller]

Hm... just wonder on those "every day" people: How much variation do you get?
How much is due to routine errors in handling the standards? How does the variation compare to errors in weighing crystalline material, as an example? Do you meaure the temp. everyday with a calibrated (every day) thermometer to correct correctly the buoyancy?
For what is the built in selfcalibration?

[unmgvar]

I think that if you posses an analitical balance that can adjust itself and perform an internal calibration check to itself, then you do not need to perform an external check everyday as well.
our SOP's direct us to perform an external check once per month using E2 standard weight ranging from 10 mg, 100 mg, 1 g, 10 g, 100 g. the balance are check for both precision check (for exemple XX.XX mg and XX.X mg)
every 6 month we add a repeatability check for the lowest value.
every 6 month the balances are check by a technician to see if the internal adjustment and cheks works properly.

last year we had a small earthquake that was felt in the laboratory and we did check if there was any deviation to the standard weight. eventhou we found no deviaton, we still decided to readjusted and recalibrated the balances and then checked them to the standards just to be on the safe side.
Did we overeacted?
Could we have just done the internal adjustment and calibration?
on the balance side, I believe that we over did it, on the QA side,if an inspector had known of that earthquake, we covered ourself to the full extent.

i gave the exemple to emphises the point that from the all the posts the entire subject seems to be a lot in the eye of the beholder.

do we or do we not trust the automated functions of the balance for daily use?
fact remains that according to the FDA guidance, we do not need to externaly check daily the balances if an automated chek exists. we do however need to check the automated mechanism once in a while.
modern balances can perform automated adjustment to themselfs due to temp. deviation, and be more accurate then an external weight (that we would check only once per year)
what if the weights turn out to be out of spec?
do we cancel all the work done in the previous year?
do we start checking our standards weight for more then once per year?
I think that like we trust that the internal check of the UV detector or other critical instruments we can trust the internal adj. and calib. of our balances, especially if we have an FDA guidance to back us up.
apart from out of the ordanary days(like an earthquake, we do not need to overreact in our checks).

and there is yet to be found a good answer, to what do we do with all the work done between 2 OQ's with an instrument when the last OQ fails, that is different then just do more checks in smaller intervals

[rnelson]

I don't see anything wrong with performing the internal calibration procedure every day, but how do know it was performed properly unless you place a couple of check weights on the pan?

When our vendor performs their external calibration every 3 months, they do "as found" and "as left" data. "As left" is a check that his calibration procedure was performed properly.

So, if you need to check your internal calibration anyway, why not just perform the daily weight check and only do the internal calibration if your daily check fails, then perform daily again.

[KarenJ]

The biggest reason that I am for doing a daily check is because the USP requires it. If you don't do a daily check, how do you justify not following the pharmacopeia? At the big pharma company that I used to work for, we just used the internal calibration and internal weight check for years with only an annual external check until our QA people (as a result of an FDA audit and 483 I believe) told us that we had to start doing a daily external check. There probably is some variability in the results due to temperature fluctuations, handling of the weights, etc. but as long as you fall within +/- 0.2mg of the theoretical mass, it passes the criterion.

Of course if you are working in the lab and have SOPs in place governing your activities, your primary job is to follow those SOPs even if they are in conflict with the USP. It is QA's job to worry about SOPs that are out of compliance.

It's interesting how much differing opinion this seemingly simple topic has generated. As always with this forum, I've learned a lot from all of the contributors.

KarenJ