[Al Gerhart]

Hi All,

I am a granite fabricator and am concerned with the heavy metal concentrations in some types of granite.   From what I can tell, the professional testing labs charge quite a bit for testing.  No doubt they must to do the job right, and I would prefer that the final testing on any problem granite types found  be done by a professional lab, but it would be a lot cheaper if I could learn to do some crude surveys to identify the worst offenders.

From my research into the radioactive element content of granites, I know there can be quite a few types of heavy metals, lead of course, Selenium, Cadmium, Arsenic, and plenty of others.  Of course Lead tests are cheap and easy to use, but are they that accurate?

 The other "swab" type kits are available for a few heavy metals are a bit more expensive, but within our meager budget.  Yet I wonder if the same type test can be done less expensively with bulk chemicals instead of the swab kits.

So, I thought before I started searching the forum for info, I would introduce myself to the regulars and ask for any pointers they might be willing to share.

Thanks,
Al

[Johnny010]

Column chromatography.

[marquis]

The answer is not cheap.

A nondestructive method, such as energy dispersive x-ray flourescence (EDXRF) sounds like the best answer.  Some of the newer instruments are handheld.  Still, you are probably looking at $10K.  The handheld units can be taken to the granite.  Some of the more expensive units require the sample to come to them.  The upper price range of the EDXRF instruments can easily exceed $100K.

The lead probably wont extract from the granite.  So the swab kits probably wont work.

Other methods, such as atomic absorption, would also have trouble extracting from the granite.  Often, you need to use nasty acids (like HF) for this kind of work.

[Cultivator]

I agree with marquis.
Flame Ionization is the cheapest, but you need standards, you need to convert graphite to useful form of sample (liquid)

HF will eat through almost anything, it reacts with glasses and almost anything else.