啤酒中pH值检测方案

pH ofWine/BeerpH ofWine/Beer pH ofWine/Beer Star SeriesMethod Note M-1408-E 03/05 RevB 4 Wait for a 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 ofthe electrode. °pH·Wine/Beer·Orion ROSS"Sure-Flow@pHElectrode Introduction pH measurements are made in solutions which contain relatively large amounts of acid or base. Underthese conditions， conventional pH electrodes make measurements quickly and precisely. Recommended Equipment Catalog# 7. Place the electrode and stirrer into beaker with the pH 4.01 buffer standard such that the electrodetip is fully immersed in the solution. The stirrer should be positioned slightly below the tip of theelectrode. Press the STIRRER key on the meter to turn the stirrer on. pH in Wine/Beer Application Package (includes all items with a catalog number)1010139 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. 1. 3 Star benchtop pH meter11120002. R1OSSSure-Flow°pH electrode8172BNWP3. Stainless Steel ATC probe927007MD4. Orion benchtop stirrer (or magnetic stir plate and bar)096019 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. 5. Orion benchtop electrode stand 1110001 10. Rinse the 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. 6.Beakers (50 mL) 7. Graduated cylinder (30mL) 11. Place the electrode， ATC probe and stirrer into prepared sample such that the electrode tip is fullyimmersed in the solution. Press the MEASURE key on the meter； the stirrer will turn on. The pHicon will flash as the measurement is being made. The pH icon will become solid and the displayvalue will freeze when a stable reading is achieved. This value is logged and printed automatically andthe stirrer turns off automatically. Required Solutions Catalog# 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 919110 4. Reference filling solution， ROSSreference filling solution 810007 Remember to rinse electrodes with deionized water between measurements. Penetrate each sample to thesame depth to reproduce sample measurement. Upon completion of samples， rinse the electrode withdeionized water and store the electrode according to the instructions in the Electrode Storage section ofthis method note. 5. Electrode storage solution 910001 6. Deionized water Calibration Standard Preparation 1. Using a graduated cylinder， transfer 30 mL of the pH 7.00 buffer into a 50 mL beaker. 2. Using a graduated cylinder， transfer 30 mL of the pH 4.01 buffer into a 50 mL beaker. Sample Preparation 1. Using a graduated cylinder， measure 30 mL of the wine or beer sample into a 50 mL beaker. Mixsample with Orion stirrer. 2.Repeat this procedure for additional measurements. Results Five aliquots of the wine and beer samples were measured. Wine sample pH Sample #1： 3.00 Environmental Instruments Sample#2： 3.10 ( www.thermo.com ) ( Water Analysis Instruments 166 Cummi n gs C enterBeverly， MA 01915 USA M - 1 4 08 - E 03/05 RevB2 4 8100 - 0 0 1 ) Toll Free：1-800-225-1480Tel：1-978-232-6000Dom. Fax： 1-978-232-6015Int'lFax： 978-232-6031www.thermo.com/waterO 2005 Thermo Electron Corporation Sample # 3： 3.10 ISO9001：2000 Sample#4： 3.00 Sample#5： 3.10 All rights reserved 4 of4 Mean： 3.06 Standard Deviation： 0.05 %CV： 1.8 Beer sample pH Sample #1： 4.261 Sample # 2： 4266 Sample # 3： 4.271 Sample #4： 4.273 Sample #5： 4.252 Mean： 4.265 Standard Deviation： 0.008 %CV： 0.20 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. 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. 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. Tomaintain an adequate flow rate， the level of filling solution must cover the end of coil and be at least oneinch above the sample level when immersed. The filling hole should be open whenever the electrodeis in use. 4. Thoroughly wet the reference junction by pressing down on the electrode cap and allowing some of theROSS" internal filling solution to flow out of the electrode through the junction. Replenish lostfilling solution. 5.Shake down the electrode to remove air bubbles. Meter Setup-3 Star For initial meter setup， follow the steps in the Quick Reference Guide attached to the meter itself. The QuickStart Guide also contains a layout of the meter keypad for reference. The words in this method representedin all capital letters， such as POWER， indicates a key on the meter， and words in quotations such as “Unit"indicates information on the meter display. 1.Connect the electrode to the meter. 2. Connect the ATC probe to the meter. 3. Connect the stirrer to the meter. 4. Press the POWER key on the meter to turn the meter on. 5 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 DOWNarrowkeys to change the measurement mode of the top line to pH. .6 Press 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. 7. Press the LINE SELECTION key to select the bottom line. Press the UP or DOWN arrow keys to select“0.01 (wine) or 0.001 (beer)" for“rES" which is an abbreviation for resolution or number of significantdigits. Press the LINE SELECTION key to accept value. .8 Press the LINE SELECTION key to select the middle line， and press the UP or DOWN arrow key toselect “bUF” which is pH buffer. 9Press the LINE SELECTION key to select the bottom line， and press the UP or DOWN arrow key toselect“USA”which is US/Orion° buffers. 10. Press the LINE SELECTION key to accept and select the pH setup menu line (top line). 11. 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. Note： The Orion Benchtop Stirrer must be turned on in General Instrument Setupbefore analysis， please see the Quick Start Guide for instructions. Calibration and Analysis 1.Allow all the standards and the samples to attain room temperature for precise measurements since themeasurement is temperature sensitive. 2 Calibrate the meter using the pH 7.00 buffer followed by the pH 4.01 buffer， stirring the standards at auniform rate. 3 Place electrode， ATC probe and Orion stirrer into beaker with pH 7.00 buffer standard such that theelectrode tip is fully immersed in the solution. The stirrer should be positioned slightly below the tip of theelectrode. Press the STIRRER key on the meter to turn the stirrer on. Press the CALIBRATE key. of of of