[ExI] Ants to spike
brentn at freeshell.org
Wed Oct 21 17:16:25 UTC 2009
On 21 Oct, 2009, at 12:02, Eugen Leitl wrote:
> On Wed, Oct 21, 2009 at 11:47:29AM -0400, Brent Neal wrote:
>> Clearly, you've never used an XRF. :) Less than 2 minutes of sample
> I have. I just don't have one in the house right now. Can I borrow
You need to schmooze the grad students more. :) Certainly, if there
is a quick, dirty chemical analysis, you can get your instant
gratification. But even with something as simple as the lead
precipitation, if you don't have nitric acid laying around, you're
going to struggle. It all depends on what you have going for you and
who you know. Most ppl don't have a CNC machine, but if you need to
get things milled, I'd bet you that you've made friends with someone
who owns/works at a machine shop.
You could also build your own XRF - in principle, all you need is an x-
ray tube, a photomultiplier tube, and some monochromator optics. If
you really wanted to gild the lily, you could get a bell jar, and a
tank of helium.
>> prep (load powder or flak into PP vial) and about 2 minutes of scan
>> time. Look for lead peak. Done. XRF is widely used in industry for
>> quick assay, especially in environmental analyses. Just cause its
>> "instrumentation" doesn't make it complicated! Spectroscopy is well-
>> accessible to a citizen scientist.
>> Also, you need more than eye for lead chromate, because how will you
>> tell it from other blue pigments?
> That's because if it's an old house with oil paint which looks
> like this http://images.google.com/images?q=lead chromate
> there aren't too many options.
I agree that looks distinct. However, I'm not sure if I'd trust my
aging eyeballs to distinguish a small chip with lead chromate from
some cobalt compound. :)
Brent Neal, Ph.D.
<brentn at freeshell.org>
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