Typical Experiments. How it Works

Transcription

1 ph Sensor DT016A The ph sensor can be connected to the Nova5000, MultiLogPRO or TriLink data loggers. The ph sensor is capable of measuring the entire range of 0-14 ph and is used for various experiments in Biology, Chemistry and Environmental Science. This sensor can replace the traditional ph meter and in addition, it automatically collects the ph data and the ph changes during chemical reactions and displays these changes in a graph. The ph sensor (DT016A) consists of the Fourier Systems adaptor (DT017) and a ph electrode (DT018) and is equipped with an automatic temperature compensation system. Typical Experiments Acid Base titration Investigation of water quality Acidification of milk and others foods ph measurements in tissue extracts Alcoholic fermentation in yeast How it Works The ph electrode contains two half-cells. One contains a reference element of known H + -concentration. The other, at the bottom of the electrode, is an H + - sensitive glass membrane. The adaptor measures and amplifies the potential difference between the 1

2 two half-cells. The ph level (ph= log (H + )) is calculated from the potential difference. Sensor Specification Range: Accuracy: Resolution (12-bit): Temperature Compensation: 0-14 ph ± 2% over entire range, after temperature compensation ph Yes Operating Temperature: 0 C 50 C Response Time for 95% of Reading: Default Sample Rate: Feature: Sensor Storage: 10 seconds 10 samples per second Equipped with an offset calibration screw Store the ph electrode in its storage solution when not in use Contents Adaptor & electrode set DT016A Adaptor only DT017 Electrode only with a bottle containing ph 4.01 buffer DT018 Adaptor & electrode set DT-016A Adaptor only DT-017 Electrode only DT-018 2

3 Equipment Setup 1. Connect the electrode to the adaptor. 2. Connect the adaptor to the data logger's input. Required Equipment Nova5000, MultiLogPRO or TriLink data loggers Wash bottle with distilled or deionized water Several clean beakers Lab wipes Technical Notes If other electrochemical type sensors (Oxygen and Conductivity) are placed in the same solution at the same time and connected to the same data logger, they can interfere with each other s signals. Keep the sensors as far apart as possible - the distance required will depend on the conductivity of the solution. If there is still a problem, try connecting the sensors to different data loggers or take readings using one sensor at a time. In order to use temperature compensation a Temperature sensor must be connected to the data logger along with the ph sensor (the Temperature sensor must be plugged into Input 1). Preparation of the Electrode for Initial Use 1. Remove the protective bottle or cover from the electrode and thoroughly rinse the electrode with distilled water. Wipe carefully with a clean lab wipe. 2. During shipment, air bubbles may have migrated into the electrode sensing bulb. Hold the electrode up to the light and inspect the sensing bulb for air bubbles. If air is seen, carefully shake the electrode downward (like a thermometer) to dispel the air bubble from the sensing bulb at the tip of the electrode. Calibration The ph sensor is shipped fully calibrated. For experiments that require very accurate calibration, however, the ph sensor is equipped with an offset calibration screw. The screw is located at the back of the sensor case. Place the electrode in a reference solution (buffer of ph 7) and start recording. Insert a flat screwdriver to the calibration hole and slowly turn the calibration screw until the reference value is reached. 3

4 Using the ph Sensor with Fourier Data Loggers and MultiLab Software 1. Rinse the electrode with distilled water and blot with a lab wipe. 2. Launch the MultiLab software (from either your PC or Nova5000). 3. Connect the Temperature sensor (DT029) to the data logger s first sensor input I/O Connect the ph sensor to I/O The Temperature and ph sensors are automatically recognized by the MultiLab software. 6. Click Setup on the main toolbar and program the data logger s sample rate and number of samples. 7. Place the electrode in a beaker containing the sample and a stir bar. 8. Click Run on the main toolbar to start the measurement. Maintenance At the end of the measurement, remove the electrode from the sample; rinse the electrode with distilled water over the waste beaker. Blot the electrode dry with a lab wipe. The electrode is now ready to read the ph of other samples. When not in use, store the ph electrode in the supplied bottle containing the storage solution. The recommended storage solution is comprised of 50% ph 4 buffer and 50% 4M KCl salt. If this storage solution isn't available then a fresh ph 4 buffer can be used as well. Cleaning the Electrode Do not use strong solvents (e.g. acetone, carbon tetrachloride, etc.) to clean the ph electrode. Be sure to recalibrate the electrode after cleaning. 1. If the electrode has become coated with oil or grease, carefully wash the electrode under warm tap water using dish-washing detergent. Rinse thoroughly with fresh tap water followed by a rinse with distilled water. Soak the electrode in ph electrode storage solution for 30 minutes after this cleaning procedure. Recalibrate the electrode before use. 4

5 2. If the electrode has been exposed to protein or similar materials, soak in acidic pepsin, ASI part number CS 0003, for 5 minutes. Rinse thoroughly with distilled water. Soak in storage solution for 30 minutes prior to recalibration. 3. If the previous cleaning procedures fail to restore response, soak the electrode in 0.1 N HCI for 30 minutes. Rinse thoroughly with distilled water. Recalibrate before use. 4. If electrode response is still not restored, replace the electrode. An Example of using the ph Sensor Acidification of milk In this experiment we follow ph changes in milk, kept in a thermos, during 30 hours of incubation. Figure 1: Acidification of milk Troubleshooting If the ph displays values which are out of the sensor range, verify that the sensor cables are properly connected. 5

6 Technical Support Please contact Fourier technical support as follows: Web: Consult the FAQs before contacting technical support: Copyright and Warranty All standard Fourier Systems sensors carry a one-year warranty, which states that for a period of twelve months after the date of delivery to you, it will be substantially free from significant defects in materials and workmanship. This Warranty does not cover breakage of the product caused by misuse or abuse. This Warranty does not cover Fourier Systems consumables such as electrodes, batteries, EKG stickers, cuvettes and storage solutions or buffers. 6