Turner Designs TD-700, Руководство по эксплуатации

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TD-700 Laboratory Fluorometer Operating Manual
Page 43
Drift The change in measurement of the same sample over
time.
Dynamic Range
(maximum range)
The range of concentrations that can be read by the TD-
700 at the current level of sensitivity. Since zero is
frequently assumed to be the minimum, dynamic range
in this manual often refers to the maximum concentra-
tion that can be read. The user can select the desired
maximum (Max Range) during calibration in the Direct
Concentration calibration procedure.
Fluorescence The TD-700 Fluorometer measures the concentration of
various analytes in samples of interest via fluorescence.
A fluorescent molecule has the ability to absorb light at
one wavelength and almost instantly emit light at a new
and longer wavelength. A fluorescent molecule has a
unique “fluorescence signature,” which allows one
substance to be distinguished from another. In a
fluorometer, light from a lamp is passed through an
excitation filter that transmits light of a wavelength range
specific to the sample compound being measured. The
light passes through the sample, which emits light
proportional to the concentration of the fluorescent
material present and proportional to the intensity of the
exciting light. The emitted light is passed through an
emission filter that selects for the appropriate wave-
length range, and the resultant light is then detected by
a photomultiplier tube.
Gain An indicator of the sensitivity of the instrument usually
expressed in powers of 10.
Linear Range The concentration range in which standards correlate
with a straight line. Usually expressed as a concentra-
tion maximum such as 100 ppb.
Noise The amount of fluctuation in the instrument's measure-
ment due to the instrument or detector itself.
Optical Path Length The length of sample through which light passes. This
is defined by the cuvette size and adaptor used.
Quenching A phenomenon which occurs when the fluorescence
measurements decrease even though analyte concen-
tration is increasing.
Raw Fluorescence Refers to the “relative” fluorescence of a substance
being read, rather than the actual concentration. “Raw
Fluorescence” is a user-selected TD-700 calibration
procedure which, after calibration, provides the “fluores-
cence intensity” of samples relative to the standard and
to each other.