Separation of dinitrotoluene isomers by RPHPLC

[joho]

Back again! Anyone know anything about explosives and /or HPLC?

 

Have analysed solutions of 2,3-DNT and 3,4-DNT and a mixture of the two by reverse phase HPLC. The 2,3-DNT elutes first, only slightly quicker than 3,4-DNT, so am assuming 2,3 is slightly more polar than 3,4 because it prefers the mobile phase, hence quicker elution. But is it also something to do with the positions of the nitrite groups?

 

And I actually got a double peak in the 3,4 DNT - any ideas why that might be?:confused:

 

Thank you in advance all you very clever peeps!:rant: