Does anyone know what testing methods provide *reliable*
concerning levels of heavy metals in a person's
G’day, Colleen; There are a number of reliable tests for
potentially toxic metals in enamels or anything else. The problem
is however that the ordinary user does not have the apparatus,
equipment, chemicals or skills to carry them out. Let me expand a
bit on that:
The simplest (and oldest) methods of analysis consist firstly of
getting the material into water-solution. Prolonged heating with
borax can achieve this. Then comes a very precise series of tests
which must be done in strict sequence - quite a laborious business,
and although there is little need for really expensive apparatus, a
large variety of chemicals are required and a good deal of skill
Another method is X-ray analysis whereby a beam of X-rays is fired
at a sample (which can be very small). This beam exites the atoms
in the sample to fluoresce (give off X-rays at a lower and
predictable frequency) The wavelengths of this fluorescence can be
measured and the presence of specific elements deduced from it.
Then there is ordinary spectroscopy, where the sample is
vapourised by great heat and the atoms are excited to produce
specific wavelengths of light (including ultra-violet) The
resultant light is a sort of ‘fingerprint’ of each variety of atom
present and thus the composition of the sample is revealed.
Now how about Atomic Absorption Spectroscopy? A solution of the
sample is sprayed into the flame of an uncontaminated gas, often
pure hydrogen. A very special sort of lamp shines a light through
the flame, and that light is produced by the exitation of the atoms
of metals in the various lamps used. The similarly excited atoms
in the flame absorb some of that light thus producing gaps or dark
lines in the spectrum, which are of course, specific to the metals.
On occasion Neutron Activation Analysis can be used. The sample
is used dry for this mostly, and a beam of neutrons (often from a
pretty lethal mix of radium and another substance) is fired at the
sample. Some of the neutrons are captured by certain atoms (eg:
silver) which becomes very temporarily radioactive. The wavelength
of this radioactivity is specific to certain elements and thus the
composition of the sample is revealed.
Want another method? Try Mass Spectrometry. The sample is
vaporised and given a high electric charge. The tiny charged
particles are attracted to and through a grid given an opposite
charge, so they move at very high speeds. This beam of charged
particles passes through a powerful magnetic field, and since a
moving electric charge also has a magnetic field, the atoms are
deflected. The lightest atoms are deflected the most and the
heaviest atoms are deflected the least. So in effect the atoms
are weighed, answering the question "how do you weigh an atom?"
And of course, any of the elements can be identified by it’s atomic
weight. Elementary, my dear Watson.
There’s more, but enough is enough, eh?
So to sum it all up: yes, modern methods of analysis can detect
and measure precisely (even to 1 part per billion and better) the
constituents of any complicated mix of metals and other chemical
elements, and there exists methods of even determining the exact
size and shape of a molecule - and whether it is left or right
handed! By, by heck - you pay heavily for the
Yes, I know I get a bit pedantic at times - but you did ask, eh?
Cheers, Johnb @John_Burgess2 in the autumn of Sunny Mapua NZ.