Chromatography Forum

Hello everyone,

I would like some opinions/advice on this.

Imagine we have a bulk (50g) of a given standard. We want to divide this bulk into 100mg vials. These vials would be used sequentially, in order to avoid moisture uptake which would happen if we continued to use the bulk. These vials would be used for internal analysis and to be sent to the client on his request.
What do you think would be the best way to control the procedure of the vials being portioned?
I would like to create a record where it says that the weighing work started at 8h and ended at 16h, the weight per vial was 100mg and 500 vials were filled. However, by saying this I think I would need a record of the weights. However doing this for 500 vials is very time-consuming.

What is your suggestion?

You are 100% correct - you would need a record of the weights. The time consuming part will be the actual weighing, not noting what the weight was, especially if you have a balance that can connect to a printer or a computer. Still, less time consuming than explaining to the client why one vial is short weight and you do not have any records.

What difference does it make what time you start and finish, and who would be interested in knowing that ?

Peter

Start and finish time would not be as important as actual time of filling for each vial, if you do record it. If the material is sensitive to exposure to moisture that would allow you to be able to see if there is any change over time since the last vial filled might have more exposure to air than the first one. If you see a trend as you use each vial then you would have one more piece of data to correlate with the results.

Definitely time consuming, but as Peter said, it would make the records much more complete and better to withstand scrutiny.

I assume that companies that perform this often (like a company that distributes calibration standards) use some sort of machine for this. It's probably not worth looking into if it's a one-time task for your company.

What could help in speeding up the process is to weigh 100mg in one vial, notice the volume and put a marker on the other vials. Then you fill everything up to the marker.

In the end you still have to record the exact mass. And this little trick assumes a same mass of the empty vial, which is not really correct...

Of course the best way would be to do it in a dry box or glove bag.

A lot depends on whether you want 99- 101 mg in each vial, or 90 - 110 mg and if you want to know the exact actual weight.

Peter

I had a coworker who did something similar. She had a spreadsheet/notebook that contained the mass of all the marked vials empty and with an aliquot of standard. Took her the better part of one day for the marking, weighing, transferring, and weighing again. What helped was that the standard was a liquid and she used a volumetric pipet to transfer the standard.

It sucks doing it, but look at it as one less thing to do later on.