The Telegraph
Since 1st March, 1999
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Belgian hunt for perfect measures

Geel (Belgium), June 11 (Reuters): Searching for that perfect piece of chocolate' Belgium is renowned for the best. But rather than one of the country’s many sweet shops, head to an obscure town in the north of the country.

There, on a leafy campus set among farms and canals you will find what is quite literally the standard in chocolate: pure cocoa butter at 100 euros ($121) for 10 grams . Here, at the European Union’s Institute for Reference Materials and Measurements, chocolate is just one of the things for which scientists have created accurate samples.

They are needed for calibrating scientific instruments and so that researchers and industries have standards against which they can measure all other products.

“Trust is nice, proof is better,” said Philip Taylor, head of the isotope measurements unit, who works in one of the most subtle areas — measuring differences between atoms.

The lab sifts and samples everything from breakfast toast to mad cow disease and its nuclear isotope unit now has a starring role in the pursuit of a more perfect kilogram. Pure samples can also have big implications for public health as when the lab rushed samples of bovine spongiform encephalopathy, mad cow disease, to the US last year.

The chocolate sample is used to align lab instruments around the world so they can discern pure chocolate from the stuff with oils from palm, illipe or mango.

Sitting in a small, sealed brown bottle, the lab’s pure chocolate in the form of cocoa butter is actually white. It took eight years to develop the complex formulas for teasing out the chemical make-up of one of the world’s favourite sweets.

It ended disputes over whether chocolate is as pure as demanded by Belgian gourmets, or more like that sold in Britain.

“We give the labs a formula and they get a value,” said Elke Anklam, head of the food safety and quality unit.

The institute, part of the EU Joint Research Centre, is similar to the older US National Institute of Standards and Technology, with a heavy emphasis on biological materials. The institute’s reference materials effectively serve as the balance weight on a scale, permitting laboratories around the world to adjust their instruments for chemical, biochemical, biological and nuclear measurements.

“We use real materials — fish, mussels, apples, grain, freeze dried orange juice, toasted bread — you melt it, mill it and bottle it,” said Hendrik Emons, head of the institute’s reference materials unit. “We are providing method validation.”

The lab can make few of the thousands of toxic chemicals and hundreds of thousands of human-made chemical compounds, so the scientists tend to choose those which help detect diseases or settle legal or health disputes.

The job is tough. Nearly 350 laboratories took up the challenge when the institute wanted to know what trace elements were in a batch of mystery water samples it sent out. Many of the results turned out to be flawed and some were off-the-chart failures. Now, the institute sends out trainers to teach methods for improving lab techniques in the 25 EU states.

The technology for measuring differences between atoms has proved important to help improve the kilogram, the last remaining of the seven basic measures not defined abstractly.

The kilogram is measured against a hunk of metal sitting in Paris, while length, time, electric current, thermodynamic temperature, luminous intensity and the number of molecules in a mole are defined through other measures. For example, the metre is defined by how far light travels in a fraction of a second.

The institute is working with national laboratories in Australia, Britain, Germany, Italy, Japan, Russia and the United States to refine the kilo, competing against other labs in the U.S. Britain and Switzerland which are pursuing an alternate route.

The Holy Grail in the search for a more accurate kilo is to more accurately count the number of molecules in a mole, which is known as Avogadro’s number. In this search, the labs rely on purified silicon — Silicon 28, with the isotopes Silicon 29 and Silicon 30 removed. If the purity is sufficient — it must be reduced from an uncertainty of 10 to the minus-seventh power to 10 to the minus-eighth power — scientists can make the physical kilogram sitting in Paris obsolete.

And that would be worth a box of chocolates.

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