Qiagen DML 3000, User Manual

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Functional Description
3-12 DML 3000 User Manual
3.10 Detector
The DML 3000 uses a single PMT to measure chemiluminescence of the microplate
wells on a 96-well microplate. It leverages both photon-counting and current-
measurement modes to optimize the dynamic range of the DML 3000.
A light detector using a PMT can be characterized by the following parameters:
Background signal
Efficiency
Sensitivity
Dynamic range
Linearity
Spectral response
3.10.1 Background signal
The background signal can be divided in two components:
A constant (baseline) component
A statistically variable (noise) component that is different for each individual
measurement
The background signal in the photon-counting mode is automatically checked at the
start of each microplate measurement. In the current-measurement mode, used at
high RLU levels, the background level is subtracted from each reported measurement.
3.10.2 Efficiency
Efficiency is the response (detector output signal) versus the input signal (light
intensity). Efficiency is the gradient of RLU versus gradient of light intensity.
3.10.3 Sensitivity
Sensitivity is related to both background signal and efficiency. Sensitivity is directly
proportional to efficiency and the background signal is inversely proportional (higher
background results in lower sensitivity).
Sensitivity describes the lowest intensity of light that can be detected as different
from background. Sensitivity is usually measured using the amount of a luminescent
substance the DML 3000 is able to detect and clearly distinguish from background
noise.
3.10.4 Dynamic range
Dynamic range is the relationship between the lowest and the highest signal that the
detector is able to quantify. The dynamic range for the DML 3000 is 10 to 5x10
6
RLU.