<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR>AVA's hunt for melamine
</TR><!-- headline one : end --><TR>More than 1,000 food samples are slated for testing, and list is growing </TR><!-- Author --><TR><TD class="padlrt8 georgia11 darkgrey bold" colSpan=2>By Grace Chua
</TD></TR><!-- show image if available --></TBODY></TABLE>
<!-- START OF : div id="storytext"--><!-- more than 4 paragraphs -->FOR more than a week now, scientists at the Agri-Food and Veterinary Authority's (AVA) laboratories have been working round the clock, testing more than 400 food samples for melamine.
To date, eight products have tested positive for the chemical, which can damage the kidneys when eaten in large enough amounts.
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</TD></TR></TBODY></TABLE>An AVA lab in Lim Chu Kang, which normally tests vegetables and meat for pesticide residues, has been co-opted into the work.
It is still carrying out its regular work - bunches of chye sim and kai lan sit in plastic bags on a work table, not far from tins of infant formula and packets of biscuits.
To test a sample of, for example, biscuits, scientists and lab staff first crush it down, and then add solvents to draw out melamine and remove unwanted proteins and other food residue.
The sample is shaken, then spun rapidly in a centrifuge to separate the solid particles from the liquids.
About 1ml of the remaining liquid is analysed in a liquid chromatography mass spectrometer, a device which measures the proportion of the different molecules in it.
Every chemical has its own unique 'signature'. If melamine is present, it shows up on a chromatogram, a graph-like readout, with a characteristic spike-like pattern.
The procedure can detect melamine even at concentrations as low as 0.01 parts per million.
Testing a batch of about 100 samples takes two days.
For now, samples sit in a chiller after they are tested.
In all, more than 1,000 food samples from milk powder to biscuits are slated for testing - and the list is still growing.
Miss Luk Seow Cheng, a scientist at the lab, said: 'We have no space for all the samples!'
Samples have thus been moved to a bigger room within the building. [email protected]
</TR><!-- headline one : end --><TR>More than 1,000 food samples are slated for testing, and list is growing </TR><!-- Author --><TR><TD class="padlrt8 georgia11 darkgrey bold" colSpan=2>By Grace Chua
</TD></TR><!-- show image if available --></TBODY></TABLE>
<!-- START OF : div id="storytext"--><!-- more than 4 paragraphs -->FOR more than a week now, scientists at the Agri-Food and Veterinary Authority's (AVA) laboratories have been working round the clock, testing more than 400 food samples for melamine.
To date, eight products have tested positive for the chemical, which can damage the kidneys when eaten in large enough amounts.
<TABLE width=200 align=left valign="top"><TBODY><TR><TD class=padr8><!-- Vodcast --><!-- Background Story -->RELATED LINKS
<!-- Audio --><!-- Video --><!-- PDF -->
<!-- Photo Gallery -->
</TD></TR></TBODY></TABLE>An AVA lab in Lim Chu Kang, which normally tests vegetables and meat for pesticide residues, has been co-opted into the work.
It is still carrying out its regular work - bunches of chye sim and kai lan sit in plastic bags on a work table, not far from tins of infant formula and packets of biscuits.
To test a sample of, for example, biscuits, scientists and lab staff first crush it down, and then add solvents to draw out melamine and remove unwanted proteins and other food residue.
The sample is shaken, then spun rapidly in a centrifuge to separate the solid particles from the liquids.
About 1ml of the remaining liquid is analysed in a liquid chromatography mass spectrometer, a device which measures the proportion of the different molecules in it.
Every chemical has its own unique 'signature'. If melamine is present, it shows up on a chromatogram, a graph-like readout, with a characteristic spike-like pattern.
The procedure can detect melamine even at concentrations as low as 0.01 parts per million.
Testing a batch of about 100 samples takes two days.
For now, samples sit in a chiller after they are tested.
In all, more than 1,000 food samples from milk powder to biscuits are slated for testing - and the list is still growing.
Miss Luk Seow Cheng, a scientist at the lab, said: 'We have no space for all the samples!'
Samples have thus been moved to a bigger room within the building. [email protected]
