Surveyor lc

The modified Comfilcon A lenses were placed into individual wells of a 24 well plate with 1 mL PBS in each well at room temperature. The PBS solution was replaced with fresh PBS every hour for up to 8 h or 15 h, or every ten minutes for 2 h or 6 h. The amount of fluorescent compound released into the collected PBS aliquots was quantified spectrophotometrically based on the above standard curve. The amount of F-Cip released into the collected PBS aliquots was quantified using LC-MS (LCQ Deca XP plus with Surveyor LC, Thermo Fisher, Waltham, MA) with electrospray ionization in positive ion mode. Samples (5 μL each) were loaded onto the analytical column at 200 μL/min (Kinetex XB-C18, 2.1 × 50 mm, 2.6 μm, Phenomenex) with the following gradient: 0-3 min, 10-75% (B); 3-7.5 min, 75-91% (B). The mobile phase consists of (A) water containing 0.1% formic acid and (B) acetonitrile containing 0.1% formic acid. Mass spectrometric parameters were as follows: 250 °C capillary temperature, 45 units sheath gas, 10 units aux gas and 4.5 kV spray voltage. Selective ion monitoring (SIM) was used for detecting F-Cip 1 and 2, and the quantification was based on the respective standard calibration curve. The detection limit for F-Cip 1 and 2 is approximately 1.5 pg based on S/N ratios.