Dose - Research Chemicals Weighing Methods for Beginners

[nanobrain]

Originally Posted by Fresh

Hope it's a good scale. It was the cheapest mg scale available lol.

nevermore so true the adage holds as in the case of precision scales - ya get what ya pay for. let me riddle you this. s'pose a certain exotic catalyst was to avail itself from the hitheryonder, say 2C-TFM. now, your lab has a choice:

1. get a 50/50 batch w/the other 50% composed of unknown toxicity contaminants - but heck, its cheap, or

2. get the fair-dinkum 100% pure material with COAs - but for twice the price.

which lab does your rat want to volunteer for? catch my, ahem, drift or should i get more precise and linear, or just repeat? ;-)

so make like the pasta eater and fork the dough! for a decent scale. your labrats life is in your hands.

strangers, say no to children.

[seechao]

I've been using a 2mg accuracy scale, and it works fine, but it has a few quirks that are quite irritating, such as auto shut off that shuts off at the worst possible time, and an auto tare "feature" that has to be the worst feature ever put on a scale. I've been thinking of upgrading to one of those used high precision metzer(sp?) lab scales, I've seen some on ebay with a pricetag arround a normal scale(100$ or so) for the realy old models, and I was wondering if anyone had tried to get one working? looks like they may be difficult to calibrate and use... but 0.1ug accuracy makes me sport a woody... I may buy one anyway just as show piece....

[boti420]

Ok so i'm torn between a Tanita 1210 and a Acculab 123, which is the better of the two?

[radiometer]

double post, please delete

[radiometer]

Reports place the Acculab as being slightly better, due to its being accurate to .001g rather than .002g. But the Tanita is definitely accurate to .002g, proven by several people using calibration masses, and for most applications this is plenty close.

The Tanita in SWIMs household (keep in mind I'm speaking of the 1210 and not the 1230 which is the current model) seems to be somewhat poor at accurately registering amounts under, say, 6-10mg. This was noted wboth with calibration masses and from observing how it behaves as powders are placed upon it. I wonder if the Acculab, being a big "fancier," might be more reliable for weighing such small amounts?

[London_Bloke]

One small thing SWIM noted with the Acculab VIC123 is that if you tried to simply put a very small amount of powder on the scale (1-8mg range) it has trouble registering it, especially if you add another very small amount (say 1-2 mg) to the original amount. Try this: let the scale zero out and verify it remains at zero for several minutes. Then put a square of glossy magazine stock on the pan and let that stabilize, but don't tare, just leave the amount on the screen. From there, you can weigh out very minute amounts of powders. This seems to work well with the Acculabs, but SWIM cannot speak for the Tanita owners.

Artificial sweeteners are excellent to practice with - they are light and fluffy, and you learn very quickly that breath control is just as much a part of all this as a steady hand. You'll find this is an excellent method to become proficient at working with very small amounts. Just be sure there are no ceiling fans or air conditioning on when you do this - you'll send Splenda everywhere, although your dog will thank you for it (this is the voice of experience). It was a bit like a Three Stooges short film at the time.

It also might explain why SWIM's Bedlington Terrier occasionally licks the fireplace hearth.

Reputation Comments on this post:

Helpful advice for a novice student.

[Triple7]

SWIM notices that heat from SWIMs hands affects the weighting. SWIM learnt, that SWIM must take hands away from the scale to get better results. Also a shadow could be measured, but the heat was a lot bigger problem. It is not wind, it is heat and SWIM is sure. Just that SWIMs hands are near the scale made the scale show about 5mg off.

[London_Bloke]

^^^ Many other SWIMmers have noticed this as well. Unfortunately the scales that can calibrate and adjust for temperature fluctuations are many times higher priced.

[Nagognog2]

Use tongs and long, stainless-steel spatulas, folks. Show your skill as a chemist! Look Ma! No hands!

And Tanitas do fine after tare. And when starting with too much and then subtracting the amount.

[delafonze19]

My issue with these highly accurate scales is that they shift around to much. The act of dropping a substance on the (platen?) causes the zero to be off and no longer be accurate. Any advice on how to stop this.

[radiometer]

^ Provided one starts with a known quantity, and proceeds carefully, that is a pefectly valid, though labor intensive, method of dividing doses. In any case, one still needs an accurate scale with which to verify that initial weight, else one is still working with unknown quantities.

[jux]

the drifter is having issues weighing small amounts (1-5 mg) because the scale seems to want to drift up and down (even in a still room with the a/c off). it is starting to get irritating to spend 30 min+ trying to get an accurate weight (to no avail). any tips on how to resolve this issue? btw, the drifter is using an acculab vic123

[trptamene]

Try using more weight.....like take the weight of a penny or quarter and then weigh the stuff out on there . Then take the mass of the coin w/ the powder and subtract the mass w/o the powder. Scales seem to work best in the middle of their range as opposed to hovering around the 0 mark.

[AbbaZaba]

There are some good tips in this thread guys, thanks. I have a question though, what does it mean if my scale's accuracy is "±0.2% +LSD"? It measures up to one mg.

[trptamene]

Swim just invested in a My-weigh Gempro250.

Found new for $100 below the MSRP

was this or the Acculab VIC-123 for $100 more, but the gempro has a lifetime warranty, the accu only 2 yrs. Also, the gempro can run on battery power which is perfect for the jeweler on the go.

Has yet to receive, but will see what she can do when does and let know.

[Synesthesiac]

[nevermind]

[Prea]

Heres what swim does:
Items required - substance, empty gelcaps, tweezers, foil, scissors, bottlecap, scale, piece of paper, and pen, haha.

First use scissors and put a hole into the bottle cap, large enough that you can put half of an empty capsule in to stand upright.

Next, wrap foil around the tip of your tweezers. I keep the foil help in place by using heat shrink tubing.

Get accurate measurements of everything (but repeatedly taking items on/off the scale to get a good measurement) - bottlecap (which has already been cut), measuring cup if you use one, and gelcaps (both halves seperate, and together if you want).

Put half of an empty gelcap into the hole you cut into the bottle cap. Use the tweezers to grab your substance and put into the gelcap. Put a bit in and measure it on the scale. And repeat until desired amount is in the gelcap.

Prea added 1 Minutes and 0 Seconds later...

(forgot to add to write down all the item's measurements on your piece of paper, and keep this stored with your scale for the future)

[Synesthesiac]

So swims looking for 0.1mg accuracy scales. And presumes decent ones like this will be pushing the £1000 mark. He wants it to come with a warranty too, at lest two years. Any suggestions? What brands have the best reputation?

[Shampoo]

Originally Posted by Prea

(forgot to add to write down all the item's measurements on your piece of paper, and keep this stored with your scale for the future)

It should be noted that not all gel-caps are created equal.

I have found that even within the same bag of gelatin capsules (stored in a cool, dark, dry environment with a desiccant), individual capsules can fluctuate as much as 8-10mg (avg. cap weight =~115mg). With a compound active at <10mg (nearly all psychedelic substituted amphetamines) and those active at <20mg (nearly all psychedelic substituted phenethylamines and tryptamines), 8-10mg can make a world of difference.

A few basic tips for the use of gelatin capsules for weighing
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A) Never handle capsules with your hands, if it can be avoided. Tweezers, forceps, or even a spatula (with a skilled hand) can be used to remove the cap from the bag and place it on/take it off of the scale.

B) Always store away from heat, light and moisture. A desiccant can be placed in the bag of caps to absorb ambient moisture.

C) Weigh each capsule before use, do not assume average weight- especially between separate bags of caps. 00 capsules do not have a ubiquitous weight, nor do 0 or 000. Do not assume that because your capsules are the same size that they are the same density or weight.

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Be safe. Weigh everything twice-- or three times, and try to use a scale with at least one decimal past the level of accuracy you require.

Synaesthesiac, see here for a comprehensive thread on accurate RC scales. I highly recommend getting a scale with an A/C adapter input, a cage for prevention of wind and ambient movement interference, and one that functions through pressure-based feedback mechanisms. Acculab scales would be a good place to start looking.

[Benga]

this thread would be nicely complemented with a sticky on volumetric dilution of RC's, starting from a scale measured dose-
not just for more dosage sensitive RC's but also simply for assaying new batches, having the ability to test approximative, under 1mg doses, say 250um or 500ug doses thanks to a more common 5 /10 or 20mg weighed dose seems important.

i've been looking around and this is pretty much all i could find here

http://www.drugs-forum.com/forum/showthread.php?t=41507

which could be better, and a sticky

b

[radiometer]

This thread could stand to be completely re-done, even. For one thing, it was written with a particular scale model in mind which was once popular but is no longer available.

Didn't someone recently post a much more technical overview, which would still be understandable to beginners?