HPLC Analysis of Acidic Herbicides in Water on a Polymeric C18 Column after SPE using Supelclean^™ ENVI^™-Carb

sample preparation

SPE (Solid Phase Extraction)

sample/matrix

Fresh 1 L water samples, dechlorinated with sodium thiosulfate when necessary, at ambient temperature and pH.

SPE tube/cartridge

Supelclean ENVI-Carb, 250 mg/6 mL (57092)

condition

10 mL DI water at 20 mL/min

sample addition

0.9 L water sample at 20 mL/min

drying

10 min using clean nitrogen

washing

10 mL DI water at 20 mL/min

elution

10 mL 0.1% phosphoric acid in methylene chloride:acetonitrile (80:20) at 5 mL/min

column

polymeric-coated silica-based PAH specialty column, 20 cm × 3 mm I.D., 5 μm (Supelco equivalent, SUPELCOSIL LC-PAH, available upon request)

mobile phase

gradient, [A]: 0.05% phosphoric acid in DI water; [B]: acetonitrile

flow rate

0.5 mL/min

column temp.

50 °C

detector

photodiode array- peak width: 0.053 min, sampling interval: 0.320 sec, monitor 210 nm & 225 nm

injection

10 μL of extract (4-5 ppb each analyte in water)