Explosives from Tap Water by GC-MS

Matrix: Tap Water; buffered to pH 2 or 7

Extracting Phase: Polyacrylate (25µL ILE Cap)

Compounds: Explosives, 200ng/mL

Immobilized Liquid Extraction (ILE) Caps provide the ability to easily extract explosives for analysis by GC-MS. Two series of 2mL tap water samples were spiked with nitrobenzene, 1-methyl-2-nitrotoluene, 1-methyl-3-nitrotoluene and 1-methyl-4-nitrotoluene at a concentration of 200ng/mL in 40mL VOA vials. The first series of samples were buffered to pH 7 with sodium phosphate, while the other set of samples had their pH adjusted to 2 with potassium tetraoxalate. All samples were salted with 10% Sodium Chloride. The sample vessels were sealed with 25µL Polyacryalate ILE Caps, inverted, and agitated by a mechanical wrist shaker for 45 minutes to allow analytes to partition from the sample into the immobilized solvent phase.

The ILE Caps were removed from the sample vessels and placed on high-recovery vials containing 150µL acetone. These vials were inverted and agitated for 15 minutes to allow analytes to partition from the immobilized phase into the acetone. The resulting extracts were analyzed by an HP-5971 GC/MS in SIM mode with a 30m x 0.25mm i.d. x 0.25µm VB-5 column. The following table displays the efficiency and pH which gave the best results for each compound:

Phase: Polyacrylate     Matrix: Water