Valeport fastCTD, Руководство по эксплуатации

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fastCTD and fastCTD plus : MANUAL-2034990662-4 | issue: 1.0
Page | 5
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2021
– Valeport Ltd
2.4.1.5.1 Quenching
Quenching refers to the reduction in fluorescence of a fluorophore. Several processes can result
in quenching:
Chloride is known to quench quinine sulphate and Fluorescein. It is, therefore, advisable to
prepare any fluorophore solutions with Reverse Osmosis (RO) or De-Ionised (DI) water.
Temperature quenching - as the temperature of the sample increases, the fluorescence decreases,
that is, fluorescence is sensitive to temperature. In order to improve accuracy, measure the
sample at different temperatures and derive corrections for changes in temperature.
Photo-bleaching (or fading) is the (permanent) degradation of a fluorophore molecule by light
resulting in lower signal levels. Photo-bleaching is dependent on exposure (intensity of light and
duration) and wavelength (UV is more damaging than longer wavelengths). Use of more robust
fluorophores is recommended to avoid photo-bleaching.
2.4.2 Turbidity
Valeport's Turbidity technology is essentially two sensors in one. The first is a “classic”
nephelometer, using a 90˚ beam angle for turbidity levels between 0 and 2000 NTU. The second
sensor uses optical backscatter -
OBS (~120˚ beam angle) for turbidity levels beyond 10 000 NTU.
Both sensors output data simultaneously, at a programmable rate, so there is no need to switch
ranges as conditions vary. Intelligent sampling and the use of a 24 bit ADC eliminates the need to
switch gain. The optical head is very compact, measuring just 20mm diameter and is rated to full
ocean depth.
Excitation\Detection: 850nm
Linear Range: Nephelometer 0 to >1 000 NTU - linear response
Optical Backscatter: 0 to 4 000 NTU - linear response
(>4,000 NTU has a non-linear monotonic response that allows
derivation of higher values using look-up tables)
Minimum Detection Level 0.03 NTU
2.4.2.1 Safety Statement
The Turbidity sensor is classified EXEMPT under the standard 62471.
As a Valeport Turbidity sensor is classified as EXEMPT a hazard label in not required.
Never look directly into the optical aperture