Spot test for borates

Helen Privett <hprivett [at] museum__vic__gov__au> writes

>We have recently attempted to purchase some turmeric test papers for
>spot testing pesticide residues for the presence of borate/boric
>acid/borax.  These have been discontinued and are no longer sold in
>Australia.  I wondered if other people had developed or know of a
>different spot test for borates?  We are seeking a quick and easy
>lab test rather than a test reliant on analytical equipment.

May I suggest that it is very easy to make your own test strips?
Take 1g of ordinary turmeric spice, add it to 100ml of ethanol /
Industrial Methylated Spirit and warm gently. Filter the bright
yellow solution, soak strips of filter paper in it and allow to dry.
That's all!

To use, acidify the sample with dilute hydrochloric acid and drop
onto a test strip.  The yellow colour will turn reddish brown in the
presence of borates.  If you allow the strip to dry and then add
ammonia solution, the brown colour will change to greenish black.
Oxidising agents interfere with the test because they bleach the
colour. Sensitivity 50mg/l.

Dr Barry Knight
Head of Conservation Research
The British Library
96 Euston Road
London NW1 2DB
+44 20 7412 7229
Fax: +44 20 7412 7658


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                  Conservation DistList Instance 22:26
                 Distributed: Sunday, November 2, 2008
                       Message Id: cdl-22-26-002
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