Re: Identifying crystals.

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Date:Wed, 18 Aug 1999 08:53:47 -0500
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Do you have a lab nearby that has a SEM with an EDX spectrometer on it? If
so, take a dried, unstained paraffin section mounted on a coverslip,
carbon-coat it and mount on a SEM stub -- the SEM lab can do this -- and
use the x-ray spectrometer. You'll get a big phosphorus peak for Ca
pyrophosphate, and obviously no P peak from Ca oxalate (unless I've
forgotten my chemistry and oxalate contains PO4).

If they have an environmental SEM with EDX, then could could take them a
piece of the lesion in fix (or fresh, but you got the sample in fix, yes?),
expose the crystals but otherwise don't treat it, and do the spectrometry.

This is simple to do and doesn't take much time or preparation. Costs
depend on the lab.


>We have a cervical spine lesion containing crystals, to date we have
>been able to identify that they are either Ca pyrophosphate or Ca
>oxalate.  Does anyone have an insight into a way to differentiate
>between these two crystal types?
>We have stained with Alizarin Red S and they are strongly positive,
>we have polarised them while using a 1/4 llambda plate and identified
>them as not Ca urates.
>As these two chemicals have similar solubilities we are finding it
>difficult to separate them in paraffin sections.
>Any ideas would be appreciated.
>Bill Sinai
>Department Manager
>Tissue Pathology
>ICPMR Westmead Hospital
>Phone 61+2+9845 7774  Fax 61+2+9687 2330

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Philip Oshel
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