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Macro 900 Operation Manual
V3
© 2013 Palintest Ltd.
www.palintest.com
Page 142 of 147
25.
Appendix 5. Optical Probes Detailed Specification and FAQs
25.1.
What are the excitation and detection wavelengths?
Each Palintest Optical Probe (with the exception of Turbidity) is effectively a
stand-alone, fixed frequency fluorometer, specially tuned to excite and detect
fluorescence of selected substances in water.
The Turbidity electrode is not a fluorometer. This electrode employs a
Nephelometric measurement technique in accordance with ISO 7027.
The following table shows the excitation peak wavelengths and detection
ranges for each electrode.
Electrode
Excitation
Peak
Wavelength
Detection
Range
Chlorophyll
470nm
>630nm
Blue-Green Algae Phycocyanin (BGA-PC)
590nm
>655nm
Blue-Green Algae Phycoerythrin (BGA-PE)
520nm
>575nm
Fluorescein Dye
470nm
>550nm
Rhodamine WT
520nm
>575nm
Refined Oil
285nm
330nm
–
370nm
Turbidity
850nm
850nm
Each fluorometer electrode (with the exception of the Refined Oil Electrode)
emits short pulses of high energy light at the excitation wavelength and
responds to fluorescence in the detection range. The deep UV excitation of the
Refined Oil Electrode is permanently on.
25.2.
How does the Refined Oil sensor work?
The Refined Oil sensor detects volatile organic compounds (VOCs) that are
found in petroleum derivatives. These include benzene, toluene, ethylbenzene,
and xylenes (BTEX).
The sensor is a fixed frequency
in situ
fluorometer that uses deep UV
wavelengths (285nm) to excite the VOCs. An emission filter is then used to
detect any fluorescence generated by the VOCs between 330 and 370nm.
The electrode measures the VOCs immediately in front of the sensor face so will
measure at whatever depth the probe is lowered to. Naturally, the probe will
only detect compounds that are actually mixed/dissolved in the water, not
those floating on the surface.
The Refined Oil electrode is ideal for customers who are interested in detecting
the presence or absence of VOC’s and measuring relative fluorescence changes
that can be used as an indication of increasing or decreasing concentrations.
The electrode is not intended for absolute, quantitative measurements. This can
only really be done using Gas or Liquid Chromatography in a laboratory.