Retention samples: how to determine quantity?

Hi,

We produce a dry powder with a very low microbiological risk. One (commercial) lotnumber  can contain about 10.000kgs of product. It takes about 25 "runs" to produce this 10.000 kgs and we now take retention samples (bags) every run. As the shelf life is 3 years, I now have a massive archive with samples which we barely use (as there have no chemical or microbiological problems appeared so far).

How can I determine the best frequency of sampling? It feels kind of safe to have this amount of samples (if there would be a problem we can narrow it down to one specific run), but it seems to me a little overdone also...

Dear Pat,

Indeed, it's good to analyse your processes sometimes, to see whether you are doing the right things.

It doesn't seem overdone when looking from the outside. You have just a lot of samples as the shelf life is long. You can look to the quantity (not the frequency) of product you sample, however it needs to be a representative quantity to carry out multiple tests in duplicate or triplicate (Micro, foreign bodies and chemical).

In case of a problem with your product, you will be very happy with your massive archive. Because it will limit the damage to your company enormously.  

Kind regards,

Gerard Heerkens

Ok thank you for your answer. I will stick to the current sampling frequency for now :-)

You can conduct an analysis to find out the purpose and frequency of the retention sample (i.e. do you use them for shelf life determination, customer complaint investigation or other purpose?), also find out the sample size requirements if there is potential contamination that requires to be re-tested to meet the regulatory standards. A side note is to understand your process to take representative retention samples.