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Thermo Electron 96-09 Скачать руководство пользователя страница 9

Checking Electrode Operation (Slope)

These are general instructions, which can be used with most
meters to check electrode operation. See individual meter
instruction manuals for more specific information.

This procedure measures electrode slope. Slope is defined as
the change in millivolts observed with every tenfold change in
concentration. Obtaining the slope value provides the best
means for checking electrode operation.

1. If electrodes have been stored dry, prepare the electrodes as

described under

Electrode Preparation.

2. Connect electrodes to meter.

For electrode with U.S. Standard Connector: Insert reference
pin-tip and the sensing electrode connector into appropriate
jacks on the meter.

For electrode with BNC Connector: Screw the connector into
the appropriate jacks on the meter,

NOTE:

Non-Orion meters may require special adapters.

Consult your meter instruction manual.

3. Place 50 mL distilled water and 50 mL of TISAB II,

or 90 mL of distilled water and 10 mL of TISAB III into
a 150 mL beaker.

4. Rinse electrodes with distilled water and place in the solution

prepared in step 3 above.

5. Select either 0.1 M Fluoride or 100 ppm Fluoride. Pipet 1 mL

of the selected standard into the beaker. Stir thoroughly.
When a stable reading is displayed, record the electrode
potential in millivolts.

6. Pipet 10 mL of the same standard into the same beaker. Stir

thoroughly. When a stable reading is displayed, record the
electrode potential in millivolts.

7. The difference between the first and second potential

readings is the slope of the electrode. The difference should
be in the range of 54-60 mV/decade when the solution
temperature is 25 °C. If the difference in potential is not
within this range, refer to

TROUBLESHOOTING.

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Содержание 96-09

Страница 1: ...F Orion 94 09 96 09 Orion ionplus Fluoride Electrode INSTRUCTION MANUAL Analyze Detect Measure Control ...

Страница 2: ...tat Face The Enhanced Lab ThermaSense Triode TRIUMpH Unbreakable pH Universal Access are trademarks of Thermo Guaranteed Success and The Technical Edge are service marks of Thermo PerpHecT meters are protected by U S patent 6 168 707 PerpHecT ROSS are protected by U S patent 6 168 707 ORION Series A meters and 900A printer are protected by U S patents 5 108 578 5 198 093 and German patents D334 20...

Страница 3: ...Techniques 9 Direct Calibration 11 Low Level Measurement 14 Known Addition 16 Titrations 22 Fluoride in Acid Solutions 24 Fluoride in Alkaline Solutions 25 Electrode Storage 26 Troubleshooting 28 Troubleshooting Checklist 28 Troubleshooting Guide 30 Assistance 32 Electrode Characteristics 33 Electrode Response 33 Reproducibility 33 Limits of Detection 34 Temperature Effects 34 Interferences 35 pH ...

Страница 4: ...electrode characteristics and electrode theory are discussed in this manual Operator instructions for Orion meters are outlined in the individual meter instruction manuals The measurement of fluoride in drinking water is an approved ASTM method Approval number ASTM D 1179 Thermo Electron Corporation Technical Service Chemists can be consulted for assistance and troubleshooting advice Please refer ...

Страница 5: ...0A 420Aplus 520A 520Aplus 525A or 525Aplus Reference Electrode For Orion 94 09 Use with Orion 90 01 Single Junction Reference Electrode For Orion 96 09 None required Stirring Accessories Magnetic stirrer or stir bars are highly recommended for laboratory measurements Graph Paper 4 cycle semilogarithmic paper for preparing calibration curves for use with digital pH mV laboratory meters Plastic Labw...

Страница 6: ...TISAB 040906 2 ppm Fluoride Standard with TISAB 040907 10 ppm Fluoride Standard with TISAB 040908 Electrode Filling Solutions Inner Chamber Filling Solution 900001 Orion 90 01 Single Junction Reference Optimum ResultsTM A 900061 Orion 96 09 Combination Electrode Total Ionic Strength Adjustor TISAB To provide constant background ionic strength decomplex fluoride and adjust solution pH TISAB II 50 m...

Страница 7: ...4 ...

Страница 8: ...al position 2 Insert the spout into the filling hole in the outer sleeve and add a small amount of filling solution to the chamber Tip the electrode to moisten the 0 ring at the top and return electrode to a vertical position 3 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 to wet the inner cone 4 ...

Страница 9: ...propriate jacks on the meter NOTE Non Orion meters may require special adapters Consult your meter instruction manual 3 Place 50 mL distilled water and 50 mL of TISAB II or 90 mL of distilled water and 10 mL of TISAB III into a 150 mL beaker 4 Rinse electrodes with distilled water and place in the solution prepared in step 3 above 5 Select either 0 1 M Fluoride or 100 ppm Fluoride Pipet 1 mL of th...

Страница 10: ...00 10 2 190 10 3 19 10 4 1 9 Sample Requirements The epoxy electrode body Orion 94 09 and Orion 96 09 are resistant to attack by inorganic solutions The electrode may be used intermittently in solutions containing methanol benzene or acetone Consult Thermo s Technical Service Chemists for information on using the electrode in specific applications Samples and standards should be at the same temper...

Страница 11: ...or calibration If the value has changed recalibrate Always use fresh standards for calibration Always rinse electrodes with deionized water between measurements see Electrode Preparation Shake after rinsing to prevent solution carry over Do not wipe or rub the sensing element Allow all standards and samples to come to the same temperature for precise measurement After immersion in solution check e...

Страница 12: ...a specific ion in the presence of a large 50 100 times excess of complexing agent Known Addition is an alternate method useful for measuring dilute samples checking the results of direct calibration when no complexing agents are present or measuring the total concentration of an ion in the presence of an excess complexing agent The electrodes are immersed in the sample solution and an aliquot of a...

Страница 13: ...mple It is useful when sample size is small or samples for which a stable standard is difficult to prepare and for viscous or very concentrated samples The method is not suited for very dilute samples It is also necessary to know the stoichiometric ratio between standard and sample Specific instructions for known addition known subtraction analate addition and analate subtraction can be found in T...

Страница 14: ...for more specific information 1 Measure 50 mL of the more dilute standard and 50 mL of TISAB II or 5 mL of TISAB III into a 150 mL beaker Stir thoroughly 2 Rinse electrode s with deionized water blot dry and place into the beaker Wait for a stable reading Then calibrate the meter to display the value of the standard as described in the Meter Instruction Manual 3 Measure 50 mL of the more concentra...

Страница 15: ...ons of the curve at least three standards are needed to determine a calibration curve In the non linear regions more points must be taken The direct measurement procedures in this manual are given for concentrations in the region of linear electrode response Low level measurement procedures are given for measurements in the non linear region 12 10 5 0 1 180 160 140 120 100 80 60 40 20 0 20 40 60 1...

Страница 16: ...oroughly 5 Rinse electrode s with deionized water blot dry and place into the second beaker When a stable reading is displayed record the mV value and corresponding standard concentration 6 Using a semilogarithmic graph paper prepare a calibration curve by plotting the mV values on the linear axis and the standard concentration values on the logarithmic axis See Figure 1 7 Measure 50 mL of sample ...

Страница 17: ...low level TISAB for standards and samples For meters with only a millivolt scale without special low level procedures or without blank correction prepare a calibration curve as follows Setup 1 Remove the plastic cap covering the electrode s tip 2 If using Orion 94 09 Fluoride Half Cell fill the Orion 90 01 Single Junction Reference Electrode with Orion No 900001 If using Orion 96 09 Fluoride Combi...

Страница 18: ...easure 50 mL of sample diluted with 50 mL of low level TISAB from a beaker Rinse the electrode s with distilled water blot dry and place into sample 5 Stir thoroughly When a stable reading is displayed record the mV value 6 Determine the sample concentration corresponding to the measured potential from the low level calibration curve Table 2 Calibration Curve For Low Level Measurements Additions o...

Страница 19: ...sured before and after addition of a standard solution Accurate measurement requires that the following conditions be met Concentration should approximately double as a result of the addition Sample concentration should be known to within a factor of three In general either no complexing agent or a large excess of the complexing agent may be present The ratio of the uncomplexed ion to complexed io...

Страница 20: ...zed water Table 3 Guideline For Known Addition Volume of Addition Concentration of Standard 1 mL 100 x sample concentration 5 mL 20 x sample concentration 10 mL 10 x sample concentration Most convenient volume to use Using a meter with direct known addition readout capability See individual meter instruction manuals for more specific information 1 Set up the meter to measure in the known addition ...

Страница 21: ...roughly 3 Rinse electrodes with distilled water blot dry and place into beaker When a stable reading is displayed set the reading to 000 0 by turning the calibration control If the reading cannot be set to 000 0 record the mV value 4 Pipet the appropriate amount of standard solution into the beaker Stir thoroughly 5 When a stable reading is displayed record the mV value If the meter could not be z...

Страница 22: ...QCstd where Cstd standard concentration Csam sample concentration Q reading from known addition table The table of Q values is calculated for a 10 volume Change The equation for the calculation of Q for different slopes and volume changes is given below Q p 1 p 10 E S 1 where Q reading from known addition table E E2 E1 S slope of the electrode p volume of standard volume of sample 19 ...

Страница 23: ...1734 9 6 0 1614 0 1642 0 1671 0 1698 9 8 0 1581 0 1609 0 1636 0 1664 10 0 0 1548 0 1576 0 1603 0 1631 10 2 0 1517 0 1544 0 1571 0 1598 10 4 0 1487 0 1514 0 1540 0 1567 10 6 0 1458 0 1484 0 1510 0 1537 10 8 0 1429 0 1455 0 1481 0 1507 11 0 0 1402 0 1427 0 1453 0 1479 11 2 0 1375 0 1400 0 1426 0 1451 11 4 0 1349 0 1374 0 1399 0 1424 11 6 0 1324 0 1349 0 1373 0 1398 11 8 0 1299 0 1324 0 1348 0 1373 1...

Страница 24: ... 0405 0 0416 30 0 0 0373 0 0383 0 0394 0 0405 31 0 0 0353 0 0363 0 0373 0 0384 32 0 0 0334 0 0344 0 0354 0 0364 33 0 0 0317 0 0326 0 0336 0 0346 34 0 0 0300 0 0310 0 0319 0 0328 35 0 0 0285 0 0294 0 0303 0 0312 36 0 0 0271 0 0280 0 0288 0 0297 37 0 0 0257 0 0266 0 0274 0 0283 38 0 0 0245 0 0253 0 0261 0 0269 39 0 0 0233 0 0241 0 0249 0 0257 40 0 0 0222 0 0229 0 0237 0 0245 41 0 0 0211 0 0218 0 022...

Страница 25: ...ining sample with lanthanum nitrate 1 Prepare a 0 1 M lanthanum nitrate solution by dissolving 43 3 g reagent grade La NO3 3 6H20 in a 1 liter volumetric flask containing approximately 700 mL of distilled water Once dissolved fill to mark with distilled water 2 Standardize the lanthanum nitrate solution by titrating against a 0 1 M fluoride standard Pipet exactly 25 mL of fluoride standard into a ...

Страница 26: ... added in unknown sample titration at endpoint Vto volume of titrant added in standardization titration at endpoint Vfx volume of sample used in sample titration 25 mL Vfo volume of standard used in standardization titration 25 mL Figure 2 Titration of 0 114 M F with 0 1 M La NO3 3 23 100 50 0 50 100 5 10 15 20 25 titrant volume mL electrode potential mV ...

Страница 27: ...uantities to dilute all samples and standards 2 Prepare a background solution containing all components except fluoride Use this solution to prepare standards 3 Prepare standards in the concentration range of the unknowns by adding fluoride to the background solutions Dilute each standard 10 1 with sodium acetate solution 9 parts sodium acetate and 1 part standard Prepare fresh standards every two...

Страница 28: ... samples and standards to the same value After both samples and standards are diluted 10 1 with the buffer solution the fluoride ion concentration can be determined in the usual manner Procedure 1 Prepare a 4 0 M buffered potassium acetate solution by diluting 2 parts 6 0 M acetic acid CH3COOH with one part distilled water surrounding the reaction with a water bath Add 50 KOH solution to the aceti...

Страница 29: ...ith distilled water and store dry Orion 94 09 The Orion 94 09 Fluoride Electrode should be rinsed thoroughly and stored dry in the air at all times When storing for long periods of time replace the cap to protect the sensing element Orion 96 09 The solution in the Orion 96 09 Fluoride Combination Electrode should not be allowed to evaporate causing crystallization For short periods of time between...

Страница 30: ...rode body by the cap with one hand and push the outer sleeve of the electrode up into the cap to drain the chamber 2 Unscrew the cap counter clock wise and then slide the cap and the epoxy coated spring up along the cable 3 Hold the outer sleeve with one hand and firmly push down on the threaded portion with the thumb and forefinger to separate the inner body from the sleeve 4 Grasp the cone with ...

Страница 31: ...B not used Samples and standards at different temperatures Sensing element dirty Incorrect reference filling solution Standards contaminated or incorrectly made TISAB not used Standard used as TISAB Defective electrode Glassware used Incorrect scaling of semilog paper Incorrect sign Incorrect standards Wrong units used Complexing agents in sample Incorrect TISAB dilution Symptom Off scale or Over ...

Страница 32: ... bubble by redipping in solution Do not use calomel reference electrode Use recommended TISAB Allow solutions to come to the same temperature before measurement Remove organic deposits see Measuring Hints Use recommended filling solution Prepare fresh standards Use recommended TISAB Use TISAB I Refer to Troubleshooting Guide Use plastic labware Plot millivolts on the linear axis On the log axis be...

Страница 33: ...ration slope 3 If electrode fails this procedure see Measuring Hints 4 Repeat step 2 Checking Electrode Operation Slope 5 It the electrodes still do not perform as described determine whether the fluoride or reference electrode is at fault To do this substitute a known working electrode for the electrode in question and repeat slope check 6 If the stability and slope check out properly but measure...

Страница 34: ...ook for possible interferences complexing agents or substances which could affect response or physically damage the sensing electrode or the reference electrode If possible determine the composition of the samples and check for problems See Sample Requirements Interferences and pH Requirements Technique Check the method of analysis for compatibility with your sample Direct measurement may not alwa...

Страница 35: ...he Technical EdgeSM for Orion products Within the United States call 1 800 225 1480 outside the United States call 978 232 6000 or fax 978 232 6031 In Europe the Middle East and Africa contact your local authorized dealer For the most current contact information visit www thermo com 32 ...

Страница 36: ...lutions to several minutes near the limit of detection See Figure 3 Figure 3 Typical Electrode Response To Step Changes in NaF Concentration Reproducibility Reproducibility is limited by factors such as temperature fluctuations drift and noise Within the electrode s operating range reproducibility is independent of concentration With calibration every hour direct electrode measurements reproducibl...

Страница 37: ...mperature because of the solubility equilibria on which the electrode depends The slope of the fluoride electrode also varies with temperature as indicated by the factor S in the Nernst equation Values of the Nernst factor for fluoride ion are given in Table 5 If temperature changes meter and electrodes should be recalibrated The electrode can be used at temperatures from 0 to 100 C provided that ...

Страница 38: ... proportion of free fluoride ion in acid solutions Hydroxide ion interferes with the electrode response to fluoride when the level of hydroxide is greater than one tenth the level of fluoride ion present For example at pH 7 when the hydroxide concentration is 10 7 M or less there is no hydroxide interference with fluoride measurements At pH 10 where the hydroxide concentration is 10 4 M there is n...

Страница 39: ...tion of solution pH hydrogen is the only complexing species Figure 5 Electrode Response in Alkaline Solutions 36 1 0 2 0 4 Cf Ct pH 0 6 0 8 1 0 2 3 4 5 6 solution pH 7 100 75 50 25 0 25 8 9 10 11 electrode potential mV 10 3 M F 10 4 M F 10 5 M F ...

Страница 40: ...eagent CDTA that preferentially complexes aluminum or iron in the sample In a 1ppm fluoride sample TISAB II or III complexes about 5 ppm aluminum or iron Higher levels of aluminum or iron can be complexed by using TISAB IV Electrode Life Electrode should last at least through the warranty period In time the electrode slope will decrease and readings will start to drift indicating that electrode sh...

Страница 41: ...bout 57 mV per decade The level of fluoride ion A is the activity or effective concentration of free fluoride ion in solution The fluoride ion activity is related to free fluoride ion concentration Cf by the activity coefficient yi A γyCf Ionic activity coefficients are variable and largely depend on total ionic strength Ionic strength is defined as Ionic strength 1 2 CiZi 2 where Ci concentration...

Страница 42: ...iffuse at different rates the electrode charge will be carried unequally across the solution boundary resulting in a potential difference between the two solutions In making electrode measurements it is important that this potential is the same when the reference is in the standardizing solution as well as in the same solution otherwise the change in liquid junction potential will appear as an err...

Страница 43: ...w samples where no filling solution adequately fulfills the condition stated above Particularly troublesome are samples containing high levels of strong acids pH 0 2 or strong bases pH 12 14 The high mobility of hydrogen and hydroxide ions in samples makes it impossible to swamp out their effect on the junction potential with any concentration of an equitransferent salt For these solutions it is r...

Страница 44: ...onal charges including freight for warranty service performed in some countries For service call Thermo or its authorized dealer outside the United States and Canada Thermo reserves the right to ask for proof of purchase such as the original invoice or packing slip Field Service is available on Orion BOD AutoEZ EZ Flash GC Accessory and TEA Analyzer Contact our Field Service department for details...

Страница 45: ...quid Handling Devices Liquid Handling Automation Workstations Orion AS2000 AS2500 and AS4000 Pumps Orion SP201 SP201 HR SP201 S Peristaltic and Rinse pHuture Conversion Box Wine Master 607 Switchbox rf link AQUAfast II Colorimeters Vacuum Degasser and Flowmeter Orion EZ Flash GC Accessory Orion TEA Analyzer 610 and 510 excluding consumable items carry twelve months warranty only Orion Ion Selectiv...

Страница 46: ...strong acid or base at temperatures above 50 C Out of Box Warranty Should any of the following products fail to work when first used contact Thermo immediately for replacement Orion Solutions Standards Reagents Cables Ferrules Tubing Line adapters Printers Software Cases Stands Probe Membranes AQUAfast Test Strips EZ Flash columns Liquid Handling Probes Adapter Plates and Racks and general accesso...

Страница 47: ... TO OR ARISING OUT OF THE PRODUCT FURNISHED HEREUNDER REPRESENTATION AND WARRANTIES MADE BY ANY PERSON INCLUDING ITS AUTHORIZED DEALERS REPRESENTATIVES AND EMPLOYEES OF THERMO WHICH ALTER OR ARE IN ADDITION TO THE TERMS OF THIS WARRANTY SHALL NOT BE BINDING UPON THERMO UNLESS IN WRITING AND SIGNED BY ONE OF ITS OFFICERS ...

Страница 48: ...Solution 475 mL 940907 100 ppm Fluoride Standard Solution 475 mL 940909 TISAB II 1 gallon bottle 940999 TISAB II case of four 1 gallon bottles 940911 TISAB III 475 mL 940916 Fluoride Activity Standard Bulk Pack includes four 1 ppm Fluoride TISAB Standard 040906 four 10 ppm Fluoride TISAB Standard 040908 040906 1 ppm Fluoride Standard with TISAB II 475 mL 040907 2 ppm Fluoride Standard with TISAB I...

Страница 49: ...0 1 M 1900 ppm F Temperature Range 0 to 80 C continuous use 80 to 100 C intermittent use Electrode Resistance 150 200 kilohms Reproducibility 2 Minimum Sample Size 3 mL in a 50 mL beaker Size Orion 96 09 94 09 Body Diameter 13 mm 12 mm Cap Diameter 16 mm 16 mm Cable Length 1 m 1 m Specifications subject to change without notice ...

Страница 50: ...rd Cambridgeshire England CB6 2HY Tel 44 1353 666111 Fax 44 1353 666001 Far East Room 904 Federal Building 369 Lockhart Road Wanchai Hong Kong Tel 852 2836 0981 Fax 852 2834 5160 Customer Support Toll Free 800 225 1480 www thermo com Dom e mail domcs1 thermoorion com Int l e mail intcs1 thermoorion com For updated contact information visit www thermo com Analyze Detect Measure Control Powered by T...

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