环境水中物理指标检测方案

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pH ofSalt WaterpH ofSalt Water pH ofSalt Water Calibration and Analysis 1. Allow all the standards and the samples to attain room temperature for precise measurements since themeasurement is temperature sensitive. 2C.alibrate the meter using the pH 7.00 buffer followed by the pH 4.01 buffer， stirring the standards ata uniform rate. 3P.lace electrode， ATC probe and stirrer into beaker with pH 7.00 buffer standard with the electrode tipfully immersed in the solution. The stirrer should be positioned slightly below the tip of the electrode.Press the STIRRER key on the meter to turn the stirrer on. Press the CALIBRATE key. 4.Wait for stable reading (1-2 minutes). Enter standard value of 7.00 using the UP and DOWN arrowkeys and the DECIMAL /DIGIT key. 5. Press CALIBRATE key to accept 7.00 standard and press the STIRRER key to turn the stirrer off. 6.Rinse electrode， ATC probe， and stirrer thoroughly with deionized water. Gently remove excesssolution from the outer sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe orrub the sensing element of the electrode. .7.Place the probes and stirrer into beaker with the pH 4.01 buffer standard with the electrode tip fullyimmersed in the solution. The stirrer should be positioned slightly below the tip of the electrode. Pressthe STIRRER key on the meter to turn the stirrer on. 8. Wait for stable reading (1-2 minutes). Enter standard of 4.01 using the UP and DOWN arrow keysand the DECIMAL /DIGIT key. 9.Press MEASURE key to accept 4.01standard and to move to the measure mode of the meter. Press theSTIRRER key to turn the stirrer off. 10. Rinse electrode， ATC probe， and stirrer thoroughly with deionized water. Gently remove excesssolution from the outer sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe orrub the sensing element. 11. Place the probes and stirrer into prepared sample with the electrode tip fully immersed in the solution.Press the MEASURE key on the meter； the stirrer will turn on. The pH icon will flash as themeasurement is being made. The pH icon will become solid and the display value will freeze when astable reading is achieved. This value is logged and printed automatically and the stirrer turnsoff automatically. 12. Repeat steps 10 and 11 for additional samples. Remember to rinse the electrodes with deionized waterbetween measurements. Penetrate each sample to the same depth to reproduce sample measurement.Upon completion of samples， rinse the electrode with deionized water and store the electrodeaccording to instructions in the Electrode Storage section of this method note. Introduction Measurement of pH is one of the most important and frequently used tests in water chemistry. Thismethod measures pH of salt water from the ocean. It utilizes the Orion Epoxy-Body， Triode"" 3-in-1pH/ATC Probe， which is ideal for field or plant use. Recommended Equipment Cat. No. pH in Salt Water Application Package (includes all items with a Cat. No.) 1010115 1. 3-Star portable pH meter 1212000 2. Low maintenance pH/ATC Triode 9107BNMD 3. Orion benchtop stirrer (or magnetic stir plate and bar) 096919 4. Orion benchtop electrode stand 1110001 5. Softpack 1210005 6. Rubber boot and storage sleeve 1210002 7.B1eakers(50 mL) 8. Graduated cylinder (50 mL) 9. Watch glass Required Solutions Cat.No. 1. pH 4 buffer pouch， 10 Pack， color coded pink 910410 2. pH 7 buffer pouch， 10 Pack， color coded yellow 910710 3. pH 10 buffer pouch， 10 Pack， color coded blue 911010 4. Electrode rinse pouch， 25 pack 911125 5. Deionized water Calibration Standard Preparation 1. Select two buffers that bracket the expected sample pH. The first should be near the electrodeisopotential point (pH 7) and the second near the expected sample pH. 2. Using a graduated cylinder， transfer 30 mL of the pH 7.00 buffer into a 50 mL beaker. 3. Using a graduated cylinder， transfer 30 mL of the pH 4.01 buffer into a 50 mL beaker. Sample Preparation Collect samples of salt water according to the Sample Collection Procedure approved by EPA.2 Using a graduated cylinder， measure 40 mL of the sample into a 50 mL beaker. Cover the beaker witha watch glass. 3 Repeat this procedure for additional samples. Results Samples of the salt water were collected. Five aliquots of this sample were measured and the pH resultsdemonstrated a good repeatability. Salt Water pH Sample #1： 7.99 Sample # 2： 7.95 Sample # 3： 7.97 Sample #4： 7.95Sample#5： 7.93 Mean： 7.96 Standard Deviation： 0.02 %CV： 0.29 Electrode Storage For brief storage periods between sample measurements (for field use)， saturate a piece of cotton with OrionpH Storage solution and place it in the Orion storage sleeve， making sure to cover the reference and sensingsurfaces to keep them moist. For longer storage periods (more than one week)， rinse off any salt build-up withdeionized water， and remove any membrane/junction deposits. Cover the sensing surface with a protective capand store dry. Equipment Setup Electrode Setup-Waterproof pH Triode 1. Remove the protective shipping cap from sensing element and save for storage. 2.Clean any salt deposits from exterior by rinsing with deionized water. For initial meter setup， follow the steps on the Reference Panel that is attached to the meter itself. The QuickStart Guide also contains a layout of the meter keypad for reference. The words in this method represented inall capital letters， such as POWER， indicate a key on the meter， and words in quotations such as “Unit"indicateinformation on the meter display. Connect the electrode to the meter 2. Connect the temperature probe to the meter these steps would probably be different 3. Press the POWER key on the meter to turn the meter on. 4.Note that the arrow on the left of the screen indicates the active line. If not the top line is not active， pressthe LINE SELECTION key to change the selected line to the top line. Then press the UP or DOWNarrow keys to change the measurement mode of the top line to pH. 5.Press the SETUP key to enter pH Setup. Press“ Fthse LINE SELECTION key to select the middle line.Press the UP or DOWN arrow keys to select “rES”which is resolution. 6..Press the LINE SELECTION key to select the bottom line. Press the UP or DOWN arrow keys to select“0.001”for "rES” which is an abbreviation for resolution or number of significant digits. Press the LINESELECTION key to accept setting. 7.Press the LINE SELECTION key to select the middle line， and press the UP or DOWN arrow key to select“bUF”which is pH buffer. 8.Press the LINE SELECTION key to select the bottom line， and press the UP or DOWN arrow key toselect“USA”which is US/Orion buffers. 9. Press the LINE SELECTION key to accept and select the pH Setup Menu line (Top Line). 10. Press the MEASURE key to return to the measurement mode. If all steps were followed correctly the meter display will show three digits in the top line and “pH" to the rightof the top line. The meter and electrode are now ready for calibration. www.thermo.com of of ff