Dose - Research Chemicals Weighing Methods for Beginners

[radiometer]

I thought it would be nice to have a thread on scale use with a bit more
focus than the "How do you measure your doses?" thread. I'm going to
describe how I weigh powders, and maybe some of you could do the
same? I'm sure my technique is not the best - it works for me, but I'd
love to improve!


Tanita 1210

First, every so often, I will break out my calibration mass set (not the 10g
weight which comes with the scale, but a set of tiny weights in varying
amount of mgs I bought seperately) to make sure that the scale is
working properly. Just a few simple tests, maybe start with 20mg, and a
few smaller and larger amounts. When I first got the weights, I spent a
LOT of time playing with them to see what this scale could and couldn't
do.

One thing it can't really do too well is register very small amounts added
slowly. In order to register smaller amounts reliably, the powder must be
put in/on something that one can pick up off of the scale and place back
down again.

In short, it IS possible to get reliable readings for small doses (say under
10mg). But it is very time-consuming, and it would just seem to risky for
me. I don't use anything that I'm trying to weigh less than say 18mg, so
this isn't a problem for me and I haven't really addressed a solution. I
think the best solution would be to buy a more professional scale.


Here's an step-by-step example, weighing 20mg using my method:

Using the gemcup, turn on scale and calibrate with the 10g weight.

Place a slick ID card (store membership cards, like from movie rental
places, work great for this) centered on the gemcup. Note the weight.
Pick up the card and place it down again a couple times to be certain of
the repeatability of this weight. Once you're satisfied with this, write
down the number and add to this the weight of your desired dose. (the
card I use weighs 3.426g, so for a 20mg dose I'll be looking for a final
weight of 3.446g)


Note: This scale has an automatic shutoff function, which is a pain in the
ass. It only takes a moment, however, to start and recalibrate the scale.
Expect to have to do this at least once if you're taking your time. I will
just go ahead and do this right before I start weighing the actual dose, so
it won't shut off halfway though.

Now just slowly add powder until you get the desired amount. You will
see that the scale doesn't really register any change as you add the first
few mg, but the final weight will be correct. When you need to remove
some, it's easier to take the card off the scale first, remove the powder,
and place the card back on. I will also do this at the end to make sure it's
repeatedly measuring the same amount.

At this point, I do a step you could do anytime earlier. I weigh the
capsule (both parts) I'm going to use in the gemcup (without the ID card),
so I can get additional confirmation of the dose's weight when I'm done.
My size 0 caps weigh 98mg consistently.

There MUST be better methods than mine for the rest, but it works for
me. I have a couple sheets of slick magazine paper ready - one for
pouring the powder, and one to place underneath while doing the
pouring, in case of spills. I fold one paper gently, carefully put the
powder near on side of the paper on the fold, pick up the paper and slide
the contents into the large side of the capsule and then close the sucker.
Some powders stick to the card and/or paper just a bit and need to be
helped along. I'm sure you can think of something to use, I use a
jeweler's screwdriver, which I also use as a spatula for getting the powder
out of the vial when weighing.

Now calibrate the scale one last time and weigh the capsule. If you've
done everything correctly, it should weigh exactly its original weight plus
the dose you wanted! Dropping the capsule in my example down into the
gemcup, I see 118mg on the readout and am ready to eat drink and be
merry.


I can see that I sure could've edited and tightened up this post a bit, but
it's ok as is, and I hope some of you will improve on it anyway.Edited by: radiometer

Reputation Comments on this post:

	this is a great thread for anyone looking into rcs. it discusses the best weighing methods and makes it a point that yo...
	Good sticky
	excellent info
	A much needed, useful thread.
	Great post. Now all I need is some scales!