TROLL 9500 Operator's Manual - Geotech Environmental Equipment

Section 15: AmmoniumSpecialized calibration kits are available for calibrating the ammoniumsensor for low-range and high-range measurements:Low range: two quarts each 14 ppm and 140 ppmHigh range: two quarts each 140 ppm and 1400 ppmRecommended Calibration FrequencyIon-selective electrodes are inherently unstable and drift is quitenormal. To achieve the most accurate sensor response, we recommenda complete three-point bithermal calibration once a week, with asingle-point calibration daily or after 4-6 hours of use.Preparing to CalibrateYou will need:3. Insert the front end of the MP TROLL 9500into the open end of the Cal Cup. Thread theCal Cup onto the body until seated against theo-ring, then back off slightly to avoid overtightening.To stabilize the instrument, you may wish touse a calibration stand or other support.4. Connect the MP TROLL 9500 to a PC andestablish a connection in Win-Situ 4 or Pocket-Situ 4. Win-Situ screens are illustrated here.The Pocket-Situ interface is similar, with theNavigation tree at the top of the screen andthe Information pane below it.Cal Cup• MP TROLL 9500 with the hydrated ammonium sensor installed andsensors or plugs in the other sensor ports• Cal Cup• One, two, or three ammonium calibration solutions, selected forthe range you expect to measure. When performing a multi-pointcalibration, begin with the lowest-concentration solution.• For a three-point bithermal calibration: a temperature bath, or containerof ice large enough to hold the Cal Cup (and stirrer, if used).• Stirrer: Use a stirrer during calibration if it will also be used in thefield—for example, in stagnant or very slowly moving water. Themore closely calibration conditions reflect field conditions, the moresuccessful the calibration. For more information on the stirrer, see“Stirring” in Section 10.Ammonium Calibration Procedure1. Rinse the Cal Cup and front end of the MP TROLL 9500 in cleanwater. Shake to dry.For best results, follow this with a rinse in a portion of the selectedcalibration solution. Discard the rinse solution.5. Select the MP TROLL 9500 in the Navigationtree.The software will automatically detect anddisplay the installed sensors. If one or moresensors is installed in the wrong port, an errormessage will be displayed. Simply removethe sensor and install it in the correct position,then “refresh” the device before continuing.6. Select Ammonium in the Parameters list. The sensor serial number(SN) and recent calibration information is displayed.63Stirrer(optional)2. Insure the black PVC base (or the stirrer) is attached to the CalCup, and fill the Cal Cup to the fill line with the selected calibrationsolution.• Begin with the lowest concentration when performing a multipointcalibration.• With a full complement of sensors installed, use the lower lineas a guide.• With 1 or 2 removable sensors installed, fill to the upper line.7. Select Calibrate.7TROLL 9500 Operator’s Manual 1060095110 rev. 007 01/09