Liquid Testing | 35
Table 2
Stock Solution Formulation for Liquid Test 1 and 2
FD&C Yellow No. 5 powder 0.092 g
Tween 20 0.5 mL
Deionized water to bring volume to: 1000 mL
Preparation of Stock Solution:
1.
Weigh out 0.092 gram of FD&C No. 5 yellow dye powder into a weigh boat.
2. Rinse the contents into a 1-liter volumetric flask.
3. Add 0.5 mL of Tween 20, or 5 mL of BioTek’s wetting agent.
4. Make up to 1 liter with DI water; cap and shake well.
This should create a solution with an absorbance of about 2.000 OD when
using 200 µL in a flat-bottom microwell. The OD value will be proportional
to the volume in the well and the amount of FD&C No. 5 dye used. You can
use a larger or smaller well volume, or add more dye or water to adjust the
solution.
Too small a well volume may result in increased pipetting-related
errors.
Liquid Test 1
A 96-well, flat-bottom microplate is required for this test (Corning
Costar #3590 is recommended). Use a new microplate; any
fingerprints or scratches may cause variations in readings.
This procedure will test for repeatability and alignment, and will reveal any problems
with the system optics.
1. Using a freshly prepared stock solution (see Procedure A on page 34 or
Procedure B on page 34), prepare a 1:2 dilution using deionized water (one
part stock, one part deionized water; the resulting solution is a 1:2
dilution). The concentrated stock solution should have an optical density of
approximately 2.000 OD or lower.
2. Pipette 200 µL of the concentrated solution into column 1.
3. Pipette 200 µL of the diluted solution into column 2
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