New Column Option for Reliable HPLC Separation of Explosives

• Separate all 17 target explosives.
• Eliminate false positives for tetryl and other difficult compounds.
• Eliminate equilibration steps and save time with isocratic analyses.

Reliable analysis of explosives is largely dependent on the selectivity and sensitivity of the analytical column. Analysis by LC often follows EPA Method 8330B, an update of the original method which now incorporates mass spectrometry (MS) as an alternative to ultraviolet (UV) detection. Typically, when analyzing by UV, a C18 primary column with a cyano- or phenyl-based confirmation column is used. However, several compounds can be problematic on these phases, including 2,6-dinitrotoluene and 2,4-dinitrotoluene which may coelute or show poor response with UV detection. Tetryl is another difficult analyte that is susceptible to both heat degradation and false positives on C18 columns. By using columns with different selectivities, analysts can more accurately identify target explosives.

The unique selectivity of the Ultra II™ Aromax column separates all 17 EPA Method 8330B analytes with no coelutions under simple isocratic conditions (Figure 1). All compounds that are typically problematic were well-resolved and positively identified. Since all compounds were separated, the Ultra II™ Aromax column is ideal for both UV and MS methodology. Further, because the mobile phase used (65% methanol) is a higher organic content than is used in typical explosives methods, it has the added benefit of improving MS sensitivity by allowing better desolvation. For labs running UV methods, the Ultra C8 column provides several elution order changes and retention time shifts relative to the Ultra II™ Aromax column, making it an ideal confirmation column for UV analysis (Figure 2).

The selectivities of the Ultra II™ Aromax and Ultra C8 columns allow definitive analyte identifications, even for difficult compounds, making them excellent choices for routine explosives analysis for both environmental and forensic applications.

Figure 1: Ultra II™ Aromax columns separate all 17 target compounds and can be used alone (MS) or with a confirmation column (UV).

HMX RDX nitroglycerin nitrobenzene 4-amino-2,6-dinitrotoluene 3,5-dinitroaniline 2-nitrotoluene 2-amino-4,6-dinitrotoluene 3-nitrotoluene PETN 4-nitrotoluene 1,3-dinitrobenzene 2,6-dinitrotoluene tetryl 2,4-dinitrotoluene 1,3,5-trinitrobenzene 2,4,6-trinitrotoluene Column: Ultra II Aromax Cat. #: RE9607575 Dimensions: 250mm x 4.6mm Particle size: 5µm Pore size: 100Å Sample: Nitroaromatics and Nitramine Explosives by HPLC, EPA 8330 B (cat.# RE33204) Inj.: 10µL Conc.: 10µg/mL each component Sample diluent: methanol Conditions: Instrument: Shimadzu Prominence® Mobile phase: water:methanol, 35:65 (v/v) Flow: 1.2mL/min. Temp.: 30°C Det.: UV @ 254nm and 210nm LC_EV0484

Figure 2: The alternate selectivity of the Ultra C8 column makes it an ideal confirmation column for UV detection.

HMX RDX nitroglycerin nitrobenzene 4-amino-2,6-dinitrotoluene 3,5-dinitroaniline 2-nitrotoluene 2-amino-4,6-dinitrotoluene 3-nitrotoluene PETN 4-nitrotoluene 1,3-dinitrobenzene 2,6-dinitrotoluene tetryl 2,4-dinitrotoluene 1,3,5-trinitrobenzene 2,4,6-trinitrotoluene Column: Ultra C8 Cat. #: RE9103575 Dimensions: 250mm x 4.6mm Particle size: 5µm Pore size: 100Å Sample: Nitroaromatics and Nitramine Explosives by HPLC, EPA 8330 B (cat.# RE33204) Inj.: 10µL Conc.: 50µg/mL each component Sample diluent: methanol Conditions: Instrument: Shimadzu Prominence® Mobile phase: water:methanol, 52:48 (v/v) Flow: 1.2mL/min. Temp.: 30°C Det.: UV @ 254nm and 210nm