HPLC Analysis of Paraquat and Diquat on SUPELCOSIL^™ LC-18 after SPE using ENVI^™-8 DSK

sample preparation

SPE (Solid Phase Extraction)

sample/matrix

drinking water adjusted to pH to 10.

sample preparation

ENVI-8 DSK, 47 mm (57172)

SPE tube/cartridge

ENVI-8 DSK SPE Disk, 47 mm (57172)

condition

10 mL acetonitrile; 2 × 10 mL reagent water; 10 mL conditioning solvent A (5 g cetyl trimethyl ammonium bromide and 5 mL conc. ammonium hydroxide in 500 mL DI water, dilute to 1 L); (2 × 10 mL reagent water; 10 mL conditioning solvent B (10 g hexanesulfonic acid, sodium salt and 10 mL conc. ammonium hydroxide in 250 mL DI water, dilute to 500 mL))

sample addition

250 mL water 100 mL/min

elution

0.5-1.0 mL acetonitrile (to cover/solvate disk); 2 × 4 mL eluting solution (13.5 mL orthophosphoric acid and 10.3 mL diethylamine in 500 mL DI water, dilute to 1 L)

column

SUPELCOSIL LC-18, 15 cm × 4.6 mm I.D., 5 μm particles (58230-U)

mobile phase

3.5 mL triethylamine and 1.0 g 1-hexane-sulfonic acid, sodium salt to 800 mL DI H₂O add orthophosphoric acid to pH 2.5, dilute to 1 L

flow rate

1.0 mL/min

column temp.

35 °C

detector

photodiode array, diquat - 308 nm, paraquat - 257 nm

injection

100 μL