XPath to get unique nodes based on child node attribute

I am trying to get a node set where a child element of each node should have 
a unique value. I think I can do this with XPath, but can't figure out what 
how to filter it. This is what I have so far. 

My XPath: 

//*[*/@QText='Analysis Description:'  and 
not(preceding::*[*/@QText='Analysis Description:' = ./*/@QText='Analysis 
Description:'])] 

Source Document:
<Analysis>
   <SS_Analysis>
        <Q_2676_2_Analysis_Descri QText="Analysis 
Description:">2,3,7,8-TCDD</Q_2676_2_Analysis_Descri>
   </SS_Analysis>
   <SS_Analysis>
        <Q_2676_2_Analysis_Descri QText="Analysis 
Description:">2,3,7,8-TCDD</Q_2676_2_Analysis_Descri>
   </SS_Analysis>
   <SS_Analysis>
        <Q_2676_2_Analysis_Descri QText="Analysis Description:">601/602 
Volatiles</Q_2676_2_Analysis_Descri>
   </SS_Analysis>
   <GW_Analysis>
        <Q_3692_2_Analysis_Descri QText="Analysis 
Description:">2(2-Butoxyethoxy)ethanol</Q_3692_2_Analysis_Descri>
   </GW_Analysis>
   <GW_Analysis>
        <Q_3692_2_Analysis_Descri QText="Analysis 
Description:">2,3,7,8-TCDD</Q_3692_2_Analysis_Descri>
   </GW_Analysis>
   <DW_Analysis>
        <Q_5066_2_Analysis_Descri QText="Analysis Description:">507 
Pesticides</Q_5066_2_Analysis_Descri>
   </DW_Analysis>
</Analysis> 

I am using msxml (browser). Thanks in advance for any help. 

Dave 

_______________________________
David Wasden
david(_at_)wasden(_dot_)com 

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