palintest Macro 900 Operation Manual

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palintest Macro 900 Operation Manual Manual pdf 59 page image

Macro 900 Operation Manual V3© 2013 Palintest Ltd. www.palintest.com Page 59 of 14715.2. PT 1552 Freshwater Blue-Green Algae (phycocyanin) ProbeFreshwater Blue-Green Algae can be measured by the MAP 2000/2100 usingthe optional PT 1552 optical probe.15.2.1. Principle of OperationThe PT 1552 Blue Green Algae optical probe is a submersible, fixed responsefluorometer, which provides excitation at 590nm and detects any resultantfluorescence above 655nm.The electrode induces the phycocyanin to fluoresce, then measures the longerwavelength light which is emitted as a result of the fluorescence process.15.2.2. Limitations of UseDetermination of BGA-PC in the field using fluorescence measurementtechniques will never be as accurate as measurements made in a lab usingeither cell counting or analysis of molecular phycocyanin after its extractionfrom cells.Factors adversely affecting accuracy include:x Interference from other microbiological species and compounds, whichfluoresce at similar wavelengths.x Differences in the fluorescent response between various species of BGA.x Differences in the fluorescent response caused by temperature.x Differences in the fluorescent response caused by ambient light.x Interference caused by turbidity.Fluorescence measurement techniques are ideal for researchers who areinterested in detecting the presence or absence of a specific substance andmeasuring relative fluorescence changes that can be used as an indication ofincreasing or decreasing concentrations.Fluorescence measurement techniques are not ideal for quantitativemeasurement. In order to obtain more accurate results, data obtainedwith the fluorometer in the field should be post-calibrated with datafrom standard laboratory analysis of grab samples acquired during thestudy.15.2.3. Calibrating the BGA-PC ElectrodeThe BGA-PC probe has two calibration points. Careful calibration is essential inorder to ensure consistent and reliable results.When a BGA-PC 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 BGA-PC probe Zero point is normally carried out during