罐头中氯离子检测方案

Chloride inCanned Food Star SeriesMethod Note M-1411-E 03/05 RevB Chloride inCanned Food Calibration and Analysis ·Chloride (assodium chloride) Introduction 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 0.5 % followed by the 5 % standard， stirring the standards at a gentleand uniform rate. ·Canned Food·Orion ionplus@lon SelectiveElectrode(ISE) The electrode method replaces titration for a measurement of chloride (as % salt) in hard cheeses，Concentrations from 0.1 to 10 % salt can be read directly on an ion concentration meter after a simpleextraction step. Higher concentrations may be analyzed after dilution. 3P.lace the electrode and stirrer into the beaker with the 0.5 % standard such that the electrode tip isfully immersed in the solution. The stirrer should be positioned slightly below the tip of the eevl.ectrode.Press the STIRRER key on the meter to turn the stirrer on. Press the CALIBRATE key. Recommended Equipment Cat No. Chloride in Canned Food Application Package (includes all items with a catalog number) 1010142 4.Wait for a stable reading (1-2 minutes). Enter the standard value of“0.5” using the UP and DOWNarrow keys and the DECIMAL/DIGIT key. 1. 4 Star benchtop pH/ISE meter 1115000 5. Press the CALIBRATE key to accept the 0.5 % standard and press the STIRRER key to turn thestirrer off. 2. ionplus°chloride electrode 9617BNWP 3. Orion benchtop stirrer (or magnetic stir plate and bar) 096019 6.Rinse electrode and stirrer thoroughly with deionized water. Gently remove excess solution from theouter sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub the sensingelement of the electrode. 4. Beakers (150 mL and 250 mL) 5. Graduated cylinder (100 mL) 7. Place the probes and stirrer into the beaker with the 5 % standard such that the electrode tip is 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. 6. Pipettes (2 mL， 5 mL， and 10 mL) 7V.olumetric flasks (100 mLand 1000 mL) 8.Watch glass 8.Wait for a stable reading (1-2 minutes). Enter the standard value of“5" using the UP and DOWNarrow keys and the DECIMAL/DIGIT key. 9. Balance 10. Stir Plate 9.Press the MEASURE key to accept the 5 % standard and to move to the measure mode of the meter.Press the STIRRER key to turn the stirrer off. 11. Blender 10. Rinse electrode and stirrer thoroughly with deionized water. Gently remove excess solution from theouter sleeve of the electrode by dabbing with a clean paper tissue. Do not wipe or rub the sensingelement of the electrode. Required Solutions Cat. No. 1. 5% sodium chloride standard as NaCl 941104 11. Place the probes and stirrer in a prepared sample with the electrode tip fully immersed in the solution.Press the MEASURE key on the meter； the stirrer will turn on. The ISE：% icon will flash as themeasurement is being made. The ISE： % 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. 2. ISA (ionic strength adjustor) for chloride electrode 940011 3. Reference filling solution， optimum results "B 900062 4. Chloride activity standard， 100 PPM 941707 5. Chloride activity standard， 1000 PPM 941708 12. Repeat steps 10 and 11 for additional samples. 6. Extracting solution (concentrate nitric acid and deionized water) 7. Deionized water Upon completion of samples， rinse electrode with deionized water and store the electrode according toinstructions in the Electrode Storage section of this method note. Note： The 100 and 1000 ppm Chloride Activity Standards can be used for samples with lower chloride concentrations. Calibration Standard Preparation 1. To prepare a 0.5 % sodium chloride standard， pipette 10 mL of the 5 % sodium chloride standardinto a 100 mL volumetric flask. Dilute to the mark with the deionized water. Mix well. 2. Extracting Solution (nitric acid)： add approximately 800 mL deionized water into a 1000 mLvolumetric flask.Pipette 6.3 mL of the concentrated nitric acid (HNO，) to the same flask， swirl tomix and dilute to the mark with the deionized water. Environmental Instruments 4.T7o prepare 0.5 % sodium chloride standard with extracting solution and ISA， pipette 5 mL of the 0.5% sodium chloride standard prepared above，and 2 mL of the ISA solution into a 150 mL beaker. Usea graduate cylinder to measure 100 mL of the extracting solution into the same beaker. www.thermo.com ( Water Analysis Instruments 166 Cummi n gs C enterBeverly， MA 01915 USA M - 1 4 11-E 03/05 R evB2 4 8103-0 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 CorporationAll rights reserved ISO9001：2000 5. To prepare 5 % sodium chloride standard with extracting solution and ISA， pipette 5 mL of the 5 %sodium chloride standard prepared above， and 2 mL of the ISA solution into a 150 mL beaker. Use agraduate cylinder to measure 100 mL of the extracting solution into the same beaker.I. Sample Preparation 1.Canned food must be blended before analysis， weigh out 5.00 g (+0.01 g) of the blended product into a250 mL beaker. Add 100 mL of the extracting solution use a graduate cylinder， and a magnetic stir bar tothe beaker. Cover the beaker with a watch glass. 2.Place the beaker on the stirrer plate and gently stirring for 10 minutes， for complete dissolution of chloride. Results Five aliquots of prepared canned food were measured for sodium chloride. The data in the table below isrepresentative of the results expected for sodium chloride in canned food. Prepared canned food % NaCI Sample #1： 0.67 Sample #2： 0.66 Sample #3： 0.64 Sample #4： 9.62 Sample #5： 0.61 Mean： 0.64 Standard Deviation： 0.03 %CV 3.98 Electrode Storage For brief storage periods between sample measurements， store the electrode in the 0.05 %(-0.01M)sodium chloride standard. The fill solution in the electrode should not be allowed to evaporate， which causescrystallization. For longer storage periods， drain the electrode. Flush the inside with deionized water and storedry with a protective cap to protect the sensing element. If electrode response is slow， polish the sensing elementby cutting off 1 inch of the polishing strip and polish the electrode-sensing element with a circular motionfor about 30 seconds. Rinse the electrode with deionized water and soak in the 0.05%(-0.01M) chloridestandard for five minutes. Equipment Setup Electrode Setup-ionplus° electrode 1. Remove the rubber cap covering the electrode tip. 2Fill outer chamber with Optimum ResultsTM B filling solution.3 Lift the spout to a vertical position. 4. Insert the spout into the filling hole in the outer sleeve and add a small amount of filling solution to thechamber. Tip the electrode to moisten the 0-ring at the top and return electrode to a vertical position.L 5 Holding the electrode by the barrel with one hand， use the thumb to push down on the electrode cap，allowing a few drops of filling solution to drain wetting the inner cone. 6. Release sleeve. If sleeve does not return to its original position immediately， check to see if the 0-ring ismoist enough and repeat steps 4-6 until the sleeve has returned to original position. Add filling solution upto the filling hole. Meter Setup-4 star benchtop For initial meter setup， follow the steps in the Quick Reference Guide， which is attached to the meter itself.The Quick Start Guide included with each meter also contains a layout of the meter keypad for reference. Thewords in this method represented in all capital letters， such as POWER， indicates a key on the meter， and wordsin quotations such as “Unit"indicates information on the meter display. 1. Connect the electrode to the meter. 2. Connect the stirrer 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 ISE. 5. Press the SETUP key to enter ISE setup. Press the LINE SELECTION key to select the bottom line.Press the UP or DOWN arrow keys to select“2”for “rES” which is an abbreviation for resolution ornumber of significant digits. Press the LINE SELECTION key to accept value. 6. Press the LINE SELECTION key to select the middle line， and press the DOWN arrow key to select “nLIn”which is an abbreviation for non-linear blank correction. 8 Press the LINE SELECTION key to select the bottom line. Press UP or DOWN arrow keys to select“off” for “nL In". Press the LINE SELECTIONkey to accept value. .9 Press the LINE SELECTION key to select middle line， and press the DOWN arrow key to select “rAng”which is an abbreviation for measurement range. 10. Press the LINE SELECTION key to select the bottom line. Press the UP or DOWN arrow keys to select“HigH”for“rAng”. Press the LINE SELECTION key to accept value. 11. Press the LINE SELECTION key to select the middle line， and press the DOWN arrow key toselect“Unit”. 12. Press the LINE SELECTION key to select the bottom line. Press the UP or DOWN arrow keys to select“PEr”(%) for“Unit”. Press the LINE SELECTION key to accept value. 13. Press the MEASURE key to return to the measurement mode. If all steps were followed correctly themeter display will show three digits in the top line and“ISE：%”to the right of the top line. The meterand electrode are now ready for calibration. Note： The Orion Benchtop Stirrer must be turned on in General Instrument Setup before analysis， please see the Quick-Start Guide for instructions. of of