THE FORESIGHT TRACE ANALYSIS LABORATORY
What Do We Do With Your Hair?
by Michael Cain, Laboratory Director
If you ever contact the Foresight Laboratory you may hear references
to washing, cooking and analysing your hair sample. You might like
to know more details of this process, so here are a few notes about
how we treat your sample.
Sampling
We rely on you to give us a good sample - ideally two tablespoonfuls
of hair, one inch (2.5cm) long taken from the nape of the neck.
Too short and it floats away during washing; too long and it shows
what your body has been doing over a period of months rather than
weeks. Put it in a paper envelope, with no sellotape, clingfilm,
or other packaging.
Washing
We do not use detergent to wash your hair, we use acetone and water.
Acetone is used in nail varnish remover and is very good at removing
grease. After washing with acetone we wash the sample with three
lots of water (double distilled and deionised laboratory water, not
tap water) and then another lot of acetone to remove all contaminants.
This is a method used in many laboratories. We dry the samples at
55°C overnight.
Cooking
The proper jargon term is digestion, which means extracting the things
we want to analyse from the sample matrix. We put 200 milligrams
(about a teaspoonful) of hair into a Teflon container and add concentrated
nitric acid and laboratory water. Then we put on a tight-fitting
lid, clip twelve samples into a turntable and place them in a microwave
oven. In effect the samples are cooked in miniature pressure cookers.
The microwave oven monitors the temperature and pressure within
the containers, heating them to 200°C and 450 psi. After this
treatment, the original sample of hair has become a pale yellow
solution, with the organic matter destroyed and the inorganic metals
dissolved. We dilute this strongly acid solution to 50 ml with
laboratory water ready for analysis.
Analysis
From your school science lessons you may remember doing experiments
with test-tubes and Bunsen burners, making pretty colours, awful
smells and loud bangs. You may also remember about atoms, and that
different elements have atoms of particular masses. Our analytical
method weighs atoms. The technique is called Inductively
Coupled Plasma-Mass Spectrometry (ICP-MS). The sample solution is sprayed
into a stream of argon (an inert gas present in the air) which
is at 6000°C. The atoms get very excited and become electrically
charged. The charged atoms pass into a vacuum chamber through a
series of small holes, and are focused by charged plates and rods,
similar to electrons in a television screen. The atoms move in
a way that depend on their mass and charge, so the machine can
separate and detect each mass in turn. By comparing the response
from the sample with that from a solution containing known amounts
of each metal the amount in the sample can be measured. If this
seems to you a complicated affair, you are right. But it has to
be so to give us the extremely low detection limits that are needed.
We want to tell reliably the difference between one and two ten-thousandths
of a percent of lead in your hair.
Quality of results
Working at such low levels we put a lot of effort into ensuring that
the data we produce are reliable. We do this in several ways.
- All our equipment is serviced by the manufacturer, and before it
is used we make sure that it is performing to their specification.
- Every day we check that the microwave oven is digesting the samples
properly. We put in a sample of hair with a known result, this is
called a Certified Reference Material (CRM); and a sample of just
acid and water as a "procedural blank".
- For every twenty samples we analyse a solution bought from an independent
supplier, certified by them to contain a known amount of each metal.
This is to check that the instrument is calibrated properly, and
is performing correctly for the last sample as well as the first.
- We repeat analysis for samples that are low or high compared with
the normal range.
Interpretation of data
Once we are happy with the results they are transferred
to the Foresight HQ for interpretation, then sent to you
with recommendations.
Turnaround times
The laboratory can handle up to two-hundred and fifty samples per
week, with results produced and ready to return to headquarters
for interpretation within seven working days of receipt at the
laboratory. Other samples
If a client has high concentrations of, say, lead or copper in their
hair sample, we can do water or dust analyses to try and find if
there is an obvious source in their environment.
Conclusion
I hope that this gives you some idea about how the Foresight laboratory
goes about its work. The written methods for the laboratory take
up six pages for preparation and sixteen for analysis, so this
has been a very short outline. It is an essential part of the Foresight
philosophy that recommendations to clients are based on solid scientific
evidence, and it is our mission to give high quality data fit for
this purpose.
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