Bio-Rad Model 550, Ultramark, and Benchmark Microplate Reader Accessories - Manual (Page 9)

The first time the instrument is turned on, or after a battery failure, the following default
information will be held in the memory.
1. 96 absorbance values of 0.000
2. Dual wavelength reading
3. Measurement filter position is #1 and Reference filter position is #2
4. Plate mixing is inactive (No)
5. Raw data report is selected, all other types are deselected
6. No blank wells are assigned
7. Upper limit is 3.500 and the Lower limit is 0.000
8. The constant type of cutoff report is selected
9. Constant cutoff value is 0.000
10. Concentration report parameters
a. # STDs = 0
b. # Samples = 0
c. Replicate STDs = 1
d. Replicate Samples = 1
e. All STD concentrations = 0.000
Limits
The microplate reader displays absorbance readings with absolute values as high as 3.500.
Out-of-range absorbance values, i.e. those with absolute values greater than 3.500, are dis-
played as either ‘*.***’ or ‘-*.***’. For example if the absorbance is 4.500, then the display
will read ‘*.***’, and if the absorbance is -4.500, the display will read ‘-*.***’.
Reports
Six types of reports can be generated by the Microplate Reader: Raw, Absorbance, Matrix,
Limit, Cutoff and Concentration.
A. The RAW DATA REPORT is the uncorrected absorbance values (without blank
subtraction). In single-wavelength mode, the reported value is the measured
absorbance. In dual-wavelength mode, the reported value is the difference between
the uncorrected readings taken with the measurement filter and with the reference filter.
B. The ABSORBANCE REPORT is the blank-corrected absorbance values. The mean
absorbance value of all of the wells designated as assay blanks is calculated and then
subtracted from all 96 values of the raw data set to produce the Absorbance Report.
Abs = Raw - mean
mean =
∑
X / n
S.D. = [ {
∑
X 2 - n*(mean) 2 } / {n - 1} ] 1/2
where mean = Blank mean
S.D. = Standard deviation
∑
X = Sum total of the raw absorbances for each blank
∑
X 2 = Sum total of the squared raw absorbances for each blank
n = Number of blanks
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