洗洁剂、清洗剂中ph的测定

pH ofSoap/DetergentpH ofSoap/Detergent pH ofSoap/Detergent 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 and ATC probe into beaker with pH 7.00 buffer standard with the electrode tip fullyimmersed 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 and ATC probe thoroughly with deionized water. Gently remove excess solution fromthe outer sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub the sensingelement of the electrode. 7.Place the electrode into beaker with the pH 4.01 buffer standard with the electrode tip fully immersedin the solution. The stirrer should be positioned slightly below the tip of the electrode. Press theSTIRRER key on the meter to turn the stirrer on. 8.Wait for a 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 4.01 standard and to move to the measure mode of the meter. Pressthe STIRRER key to turn the stirrer off. 10. Rinse the electrode and ATC probe thoroughly with deionized water. Gently remove excess solutionfrom the outer sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub thesensing element. 11. Place the electrode and ATC probe into prepared sample with the electrode tip fully immersed in thesolution. 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 whena stable reading is achieved. This value is logged and printed automatically and the stirrer turns offautomatically. 12. Repeat steps 10 and 11 for additional samples. Remember to rinse the electrode with deionized waterbetween measurements. Upon completion of samples， rinse the electrode with deionized water andstore the electrode according to instructions in the Electrode Storage section of this method note. Introduction pH measurements are made in solutions which contain relatively large amounts of acid or base， or whichcontain substantial amounts of dissolved salts. Under these conditions， conventional pH electrodes makemeasurements quickly and precisely. This method describes a procedure for the determination of the pH in liquid soap. ROSS Sure-Flow°electrodes offer stable， fast results regardless of sample composition. Recommended Equipment Cat.No. 1. 3-Star benchtop pH meter 11112000 2.ROSS Sure-Flow combination pH electrode 8172BNWP 3. ATC probe 927005MD 4. Orion benchtop electrode stand 1110001 5. Beakers (50 mL) 6.Watch glass Required Solutions Cat. No. 1. pH 4.01 Buffer (color coded pink) 910104 2. pH 7.00 Buffer (color coded yellow) 910107 3. pH 10.01 buffer (color coded blue) 910110 compensation is recommended. ROSS reference filling solution 810007 5p.H electrode storage solution 910001 6.Deionized water Calibration Standard Preparation 1. Ensure that all buffers are at the same temperature. If samples are at varying temperatures， temperaturecompensation is recommended. 2. Select two buffers which bracket the expected sample pH. The first should be near the electrodeisopotential point (pH 7) and the second near the expected sample pH. ).Using a graduated cylinder， transfer 30 mL of the pH 7.00 buffer into a 50 mL beaker. 4. Using a graduated cylinder， transfer 30 mL of the pH 4.01 buffer into a 50 mL beaker. Sample Preparation 1 Ensure that the test sample is well conditioned to room temperature. 2.Dispense approximately 70 mL of sample into a beaker. Cover the beaker with a watch glass. 3 Repeat this procedure for additional measurements. Results Five aliquots of the liquid soap were measured and the results provide representative results for pH inliquid soap. Liquid Soap pH Sample # 1： 5.38 Sample #2：Sample #3： 5.40 5.40 Sample#4： 5.40 Sample #5： 5.40 Mean： 5.40 Standard Deviation： 0.010.17 %CV： Electrode Storage To ensure a quick response and free-flowing liquid junction， the sensing element and reference junction mustremain wet and not be allowed to dry out. For short-term storage (up to one week)， soak electrode in Orion pHelectrode storage solution. If not available， as a temporary substitute， use about 200 mL of Orion pH 7 bufferwith 1 gm KCl added. For prolonged storage， the reference chamber should be filled with the fill hole cover in place. Cover thesensing element and reference junction with the protective cap containing a few drops of pH storage solution.After prolonged storage， prepare the electrode as described in the Electrode Setup section of this method. There are no specific ATC storage requirements. Equipment Setup Electrode Setup - ROSS Sure-Flow° 1.Remove the protective shipping cap from sensing element and save cap for storage. 2.Clean any salt deposits from the exterior body by rinsing with deionized water. 3. Uncover the filling hole by removing the plastic sleeve and add ROSS internal filling solution. To maintainan adequate flow rate， the level of filling solution must cover the end of the coil and be at least one inchabove the sample level when immersed. The filling hole should be open whenever the electrode is in use. 4 Thoroughly wet the reference junction by pressing down on the electrode cap and allowing some ofPthe ROSS internal filling solution to flow out of the electrode through the junction. Replenish lostfilling solution. 5.Shake down the electrode to remove air bubbles. 6 Soak the electrode in pH electrode storage solution for one hour. Meter Setup -3 Star benchtop For initial meter setup， follow the steps on the Quick Reference Guide that is attached to the meter itself. TheQuick-Start Guide included with each meter also contains a layout of the meter keypad for reference. Thewords in all capital letters such as POWER indicate a key on the meter， and words in quotations such as “Unit"indicate information on the meter display. 2. Connect the ATC probe to the meter. 1 Connect the electrode to the meter 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 the top line is not active， press theLINE SELECTION key to change the selected line to the top line. Then press the UP or DOWN arrowkeys to change the measurement mode of the top line to pH. 5. 1Press the SETUP key to enter pH setup. Press the LINE SELECTION key to select the middle line. Pressthe 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.P1ress the LINE SELECTION key to select the middle line， and press the UP or DOWN arrow key toselect“USA”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"ISE： mg/L"to the right of the top line. The meter and electrode are now ready for calibration. Note： The Orion Benchtop Stirrer must be turned on in General Instrument setup before analysis，please see the Quickstart guide for instructions. www.thermo.com of of of of