If there are built-in test procedures for the determination and adjustment of wavelength accuracy, follow the instructions of the instrument manual.In all other cases use the procedure described below. Solutions: DAD: caffeine Std. 5 from the linearity testing UV/VIS: 1.0 µg/ml anthracene solution in water Settings: Mobile phase: 15% acetonitrile in water Column: RP18, 5 µm 30-50 x 2,1-4.6 mm or capillary 2.0 m x 0.12 mm ID Oven temperature: 40 °C Flow rate: 1.0 ml/min (adjusted by using 15% acetonitrile in water) Detection: scan from 230 nm to 290 nm (DAD) Injection volume: 20 µl Method: DAD: Inject 20 µl of the caffeine solution and record the spectrum. The maximum is at 272 nm and the minimum at 244 nm. UV/VIS: fill the cell with the anthracene solution and change the wavelength from 248 to 254 nm in 1 nm steps; record the maximum of absorption. The theoretical value is 251 nm. Limits: ±2 nm