Column:

GP C18 ( 5 µm, 120 Å, 4.6x 250 mm )

Mobile phase:

dissolve 2.0 g of tetradecylammonium bromide R and 2.0 g of tetraheptylammonium bromide R in a mixture of 440 mL of water R, 55 mL of 0.067 M phosphate buffer solution pH 7.0 R, 5.0 mL of citrate buffer solution pH 5.0 prepared by dissolving 20.17 g of citric acid R in 800 mL of water R, adjusting to pH 5.0 with strong sodium hydroxide solution R and diluting to 1000.0 mL with water R, and 500 mL of acetonitrile R

Flow rate:

1.5 mL/min

Column temperature:

25 ℃

Detection:

UV 254 nm

Injection volume:

20 µL