palintest Macro 900 Operation Manual

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palintest Macro 900 Operation Manual Manual pdf 79 page image

Macro 900 Operation Manual V3© 2013 Palintest Ltd. www.palintest.com Page 79 of 14715.5. PT 1554 Rhodamine WT ProbeRhodamine WT is a fluorescent red dye that is commonly used in water flowstudies and can be measured by the MAP 2000/2100 using the optional PT1554 Rhodamine WT optical probe.15.5.1. Principle of OperationThe optional PT 1554 Rhodamine WT optical probe is a submersible, fixedresponse fluorometer, which provides excitation at 520nm and detects anyresultant fluorescence above 575nm.The probe induces the Rhodamine to fluoresce, then measures the longerwavelength light which is emitted as a result of the fluorescence process.15.5.2. Limitations of UseMeasurement of Rhodamine in the field using fluorescence measurementtechniques can be adversely affected by:x Interference from microbiological species and compounds, whichfluoresce at similar wavelengths.x Differences in the fluorescent response caused by temperature.x Differences in the fluorescent response caused by ambient light.x Interference caused by turbidity.The normal effects of temperature on the fluorescent response of Rhodamine isautomatically compensated for by the probe.15.5.3. Calibrating the RHOD ProbeThe RHOD probe has two calibration points. Careful calibration is essential inorder to ensure consistent and reliable results.When a RHOD probe is first installed, it MUST be calibrated at both pointsin order to set the probe's relative sensitivity and establish its slope.Subsequently, a single point (Zero) calibration should be carried out daily.Calibration of the RHOD probe Zero point is normally carried out duringMacroCal (see MacroCal Calibration Method).Full two-point calibration should be carried out every few months.15.5.4. Calibration Solution PreparationIn order to 'calibrate' the RHOD probe, a 100μg/L calibration solution ofRhodamine WT should be used. This is exactly the same calibration solutionthat is recommended for calibration of the BGA-PC probe.The 100μg/L calibration solution should be freshly prepared by serial dilutionfrom 200g/L standard using deionised water. The following Rhodamine WTstandard is recommended: