Biotek EL800, Руководство оператора

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Chapter 4: Instrument Qualification
BioTek Instruments, Inc.
Liquid Testing
Conducting Liquid Tests confirms the ELx800’s ability to perform to specification with
liquid samples. Liquid testing differs from testing with the Absorbance Test Plate in
that liquid in the wells has a meniscus, whereas the test plate’s neutral density glass
filters do not. The optics characteristics may differ in these two cases, thus alerting the
operator to different types of problems. The liquid tests will help to detect optical
defects or contamination that can contribute to errant readings.
•
Liquid Test 1 confirms repeatability and consistency of the reader when a
solution is used in the microplate. If these tests pass, then the lens placement
and system cleanliness are proven.
•
Liquid Test 2 can be used to test the linearity, repeatability, and alignment of
the reader if you do not have an Absorbance Test Plate. Prepare the series of
solutions of varying absorbances as described on page 119.
•
Liquid Test 3 is an optional test, and can only be performed with the “UV”
model. It is offered for those sites that must have proof of linearity at
wavelengths lower than those attainable with the Absorbance Test Plate. This
test is optional since the ELx800™ has good “front end” linearity throughout
the specified wavelength range (see page 123).
•
BioTek offers a dye solution (PN 7120779, 25 ml; or 7120782, 125 ml) that may
be used in the stock solution formulation for Liquid Tests 1 and 2, or, if you
prefer, you may use the dye solution described in
Table 3 (page 119). The
purpose of the formulation is to create a solution that absorbs light at
~ 2.000 OD full strength when dispensed at 200
μ
l in a flat-bottom microplate
well.
•
Alternatively, any solution that gives a stable color will suffice. (This includes
substrates incubated with an enzyme preparation and then stopped with an
acidic or basic solution.) Some enzyme/substrate combinations that may be
used as alternates to the described dye are shown in
Table 2.
Table 2
Typical Enzyme-Substrate Combinations and Stopping Solutions
Enzyme Substrate Stopping Solution
Alkaline
Phosphate
o-nitrophenyl phosphate 3N sodium hydroxide
beta-
Galactosidase
o-nitrophenyl -beta-D galactopyranoside 1M sodium carbonate
Peroxidase 2,2'-Azino di-ethylbenzothiazoline-sulfonic
acid (ABTS)
citrate-phosphate
buffer, pH 2.8
Peroxidase o-phenylenediamine 0.03N sulfuric acid