化学药中理化常数检测方案

pH ofTabletspH ofTablets pH ofTablets 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 ata uniform rate. 3P.lace electrode temperature probe， and 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 tipofthe electrode. Press the STIRRER key on the meter to turn the stirrer on. Press the CALIBRATEkey. 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， temperature 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 such that the electrode tip isfully 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. 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 temperature 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 such that the electrode tip is 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 when astable reading is achieved. This value is logged， printed and the stirrer turns off automatically. Remember rinse electrodes with deionized water between measurements. Upon completion ofsamples， rinse the electrode with deionized water and store the electrode according to instructions inthe“Storage"section of this method note. Repeat steps 10 and 11 for additional samples. Introduction The new Orion 4-Star pH/ISE meter and ROSSSure-Flow"combination pH electrode (cat #8172BNWP) assures drug manufacturers of the most accurate and drift-free pH measurements possible.The pH measurement of pharmaceutical tablets is critical to the health and safety of consumers. The FDAregulates the testing of over-the-counter (OTC) drugs， such as Ibuprofen tablets to ensure the safety andeffectiveness of drug products used for the prevention， diagnosis， and treatment of illness. Cat. No. pH in Tablets Application Package (includes all items with a Cat. No.) 1010154 1. 4 Star benchtop pH/ISE meter 1115000 2. RFOSS Sure-FlowpH electrode 8172BNWP 3. ATC probe 927007MD 4. Orion benchtop stirrer (or magnetic stir plate and bar) 096019 5. Orion benchtop electrode stand 1110001 6. Software 21CFR Part 11 1010007 7. Beakers (50 mL， 100 mL) 8. Graduated cylinders (50mL) Required Solutions Cat. No. 1. pH 4.01 buffer 910104 2. pH 7.00 buffer 910107 3. pH 10.01 buffer 910110 4. Reference Filling Solution 810007 5.Electrode Storage Solution 910001 6.DIeionized 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. Weigh 5 gram (+0.1) of the tablets into a 100 mL beaker. 2.Add50 mL deionized water to the same beaker. 3. Add a magnetic stir bar into this beaker. Place the beaker on stirrer-plate， stir gently for 40 minutes. Ifusing the Orion Stirrer， remove magnetic stir bar before measuring sample. 4 Repeat this procedure for additional measurements. Results Tablets pH Sample #1： 5.45 Sample #2： 5.46 Sample#3： 5.46 Sample#4： 5.45 Sample # 5： 5.46 Mean： 5.46 Standard Deviation： 0.01 %CV： 9.19 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. Equipment Setup Electrode Setup 1. Remove the protective shipping cap from sensing element and save cap for storage. 2.Clean any salt deposits from exterior by rinsing with deionized water. 3 Uncover filling hole by removing plastic sleeve and add ROSS internal filling solution. To maintain anadequate flow rate， the level of filling solution must cover the end of the coil and be at least one inch abovethe sample level when immersed. The filling hole should be open whenever the electrode is in use. 4. Shake down the electrode to remove air bubbles. For initial meter setup， follow the steps on the Quick Reference Guide that is attached to the meter itself.The Quick Start Guide also contains a layout of the meter keypad for reference. The words in this methodrepresented 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. Connect the electrode to the meter 2. Connect the temperature 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 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. 6. Press the SETUP key to enter pH Setup. Press the LINE SELECTION key to select the middle line.Press the 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“0.001”for "rES” which is an abbreviation for resolution or number of significant digits. Press the LINESELECTION 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. .9 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. 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 “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 beforeanalysis，please see the Quickstart guide for instructions. Five samples are measured and the results provide a representative results expected for pH in tablets.www.thermo.com ofof of of