Explosives

[ravenwork]

Greetings,

Trying to add some compounds to our 8330 explosives analysis, specifically nitroguanidine, nitroglycerin, and PETN. I am running a Dionex Acclaim Explosives E1 column, isocratically 55:45 water: meOH, 1 mL/min, UV detection at 210, 235, and 265.

The nitroguanidine is nowhere to be seen, probably coming out with the solvent front.

I can see nitroglycerin and PETN, and it looks like they might resolve from the normal list of compounds. However, the peaks are split, and the splitting is reproducible.

Any ideas out there?

Evan Cooper

[Mark Tracy]

My boss has been bugging me to do what you are doing, so I suppose it's time. By the way, what sample volume? 100µL per 8330? And yes nitroguanidine comes extremely early.

[gbalock]

Evan,
I don't know much about this analysis, but there are a number of things that could be causing your split peaks. The most likely reason why two peaks would split, and the rest are okay is that the injection solvent is stronger than your mobile phase, especially witrh a large injection volume. The second, a less likely reason is, that the column has developed a void at the head of the column. This usually manifests itself as all the peaks being split. I hope that this helps.

[ravenwork]

My boss has been bugging me to do what you are doing, so I suppose it's time. By the way, what sample volume? 100µL per 8330? And yes nitroguanidine comes extremely early.

Yes, 100uL.

I have no progress to report. I need to at least see the nitroguanidine, so I am trying another column. It looks like I will have to extract for nitroguanidine separately anyway, so a separate analysis is justifiable.

More later...

Evan Cooper

[ravenwork]

I don't think nitroguanidine is a good candidate for reversed phase HPLC. I tried it on a Waters ion exclusion column, and saw good retention. I have a reference method that uses a mixed-mode column, C-18 and cation exchange.

[Mark Tracy]

I have been working with nitroglycerin, ethyleneglycol dinitrate, PETN, nitroguanidine etc. for the last week. I have seen no sign of peak splitting. The Acclaim E1 resolves PETN from the 8330 mix, but not the others. The Acclaim E2 resolves PETN and EGDN, but still no success with nitroglycerine. Nitroguanidine comes in the void. I'm still working on it, but it is slow going.

The nitrate esters are somewhat susceptible to hydrolysis. Could the peak splitting be due to degraded standard?