| Abstract
| - A multicomponent mobile phase utilizing ion-exchange,ion-exclusion, and ion-pairing principles for the rapidisocratic separation of anions in low explosives residueby ion chromatography (IC) has been developed. Thenotable feature of this system is that an ion-pairing reagentand an ion-exclusion reagent are combined in the samemobile phase. Contrary to expectation, these reagents actindependently of each other in solution. The stock mobile-phase composition consisted of boric acid, d-gluconicacid, lithium hydroxide, and glycerol. Tetrapropylammonium hydroxide, an ion-interaction reagent was used toachieve pH 8.5. Acetonitrile (ACN) was added to enhanceresolution and octanesulfonic acid, an ion-exclusionreagent, was added to adjust the retention time of perchlorate. Separation of a mixture of anions common tolow explosives residue was achieved in less than 16 minusing a Waters IC-Pak Anion HR column. Optimizationstudies were performed by changing the concentration ofthe ACN and by altering the pH or the type of ion-interaction or -exclusion agents. Simulated case studieswere performed using postblast residues from pipe bombs.The results show this method to be a valid and reproducible procedure for forensic casework analysis. The practical significance of this system is that a reduction in theanalysis time and an improvement in efficiency of late-eluting peaks can be achieved without resorting to gradient elution techniques. For the analysis of anions detectedin explosives residue, the Waters IC-Pak Anion HRcolumn has proven to be a suitable replacement for theVydac 300IC405 column, which has been discontinuedby the manufacturer.
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