Instruction Manual
Bromide Electrode
1
EUTECH INSTRUMENTS PTE LTD.
INSTRUCTION MANUAL
BROMIDE ION ELECTRODE
Page 1: ...Instruction Manual Bromide Electrode 1 EUTECH INSTRUMENTS PTE LTD INSTRUCTION MANUAL BROMIDE ION ELECTRODE ...
Page 2: ...t Measurement of Bromide using a pH mV meter 6 Direct Measurement of Bromide using an ion meter 7 Low Level Bromide Determinations using a pH mV meter 8 ELECTRODE CHARACTERISTICS 9 Reproducibility 9 Interferences 10 Complexation 11 Temperature Influences 11 Electrode Response 12 Limits of Detection 13 pH Effects 13 Electrode Life 13 Electrode Storage 13 ELECTRODE THEORY 13 Electrode Operation 13 T...
Page 3: ...his solution from your own laboratory stock half fill a 1 000 ml volumetric flask with distilled water and add 425 grams of reagent grade sodium nitrate Swirl the flask gently to dissolve the solid Fill to the mark with distilled water cap and upend the flask several times to mix the solution 3 Eutech Bromide Standard 0 1M NaBr Code no EC SCS BR1 BT To prepare this solution from your own laborator...
Page 4: ...g a pipet add 10 ml of the same standard used above to the beaker When the reading has stabilized record the mV reading 4 Determine the difference between the two readings The electrode is operating correctly if the mV potential has changed by a difference of 57 3 mV assuming the solution temperature is 25 o C See the TROUBLESHOOTING sections if the potential change is not within this range Slope ...
Page 5: ... water and blot dry between measurements Use a clean dry tissue to prevent cross contamination For samples with high ionic strength prepare standards whose composition is similar to the sample Dilute concentrated samples 0 1M before measurement Use fresh standards for calibration Use 2 ml of ISA for each 100 ml of sample or standard Always check to see that the membrane is free from air bubbles af...
Page 6: ...ndard Prepare standards with a composition similar to the samples if the samples have an ionic strength above 0 1M 2 Place the most dilute solution 1 0X10 4 M or 10 ppm in a 150 ml beaker on the magnetic stirrer and begin stirring at a constant rate After assuring that the meter is in the mV mode lower the electrode tips into the solution When the reading has stabilized record the mV reading 3 Pla...
Page 7: ...e the electrode tips with distilled water blot dry and lower into the solution When the reading has stabilized record the mV reading Using the calibration curve determine the concentration directly from the calibration curve 7 The calibration should be checked every two hours Assuming no change in ambient temperature place the electrode tips in the mid range standard After the reading has stabiliz...
Page 8: ...n the solution and wait for the reading to stabilize Read the concentration directly from the meter display 10 The calibration should be checked every two hours Assuming no change in ambient temperature place the electrode tips in the first bromide standard After the reading has stabilized compare it to the original reading in Step 3 above A reading differing by more than 0 5 mV or a change in the...
Page 9: ...o 100 ml of solution as prepared in Step 3 above 7 On a semi logarithmic graph paper plot the mV reading linear axis against the concentration log axis as in Figure 1 8 Rinse the electrodes in distilled water and blot dry 9 Measure out 100 ml of sample into a 150 ml beaker add 1 ml of low level ISA Place the beaker on the magnetic stirrer and begin stirring at a constant rate Lower the electrode t...
Page 10: ...Neither accuracy of the measurement nor surface of the electrode membrane will be affected if the ratio is less than that listed in the table TABLE 3 Maximum Allowable Ratio of Interfering Ion to Bromide Ion Interference Maximum Ratio for Bromide OH 1 2 30000 Cl 1 1 400 S2O3 2 3 20 NH3 3 2 I 1 1 2 0X10 4 CN 1 4 8 0X10 5 S 2 4 1 0X10 6 1 Gran s plot titration can be used to measure mixed halides in...
Page 11: ...and standards should be at the same temperature since electrode potentials are influenced by changes in temperature A 1o C difference in temperature results in a 2 error at the 1 0X10 3 M concentration level Because of solubility equilibrium on which the electrode depends the absolute potential of the reference electrode changes slowly with the temperature The slope of the electrode as indicated b...
Page 12: ...polishing To polish the membrane 1 If using polishing paper cut off a 1 2 piece and place it face up on the lab bench 2 Put a few drops of distilled or deionized water in the center of the paper 3 Holding the paper cotton steady with one hand bring the membrane of the electrode down perpendicular to the paper and with a slight swirling motion gently polish the tip of the electrode against the surf...
Page 13: ...ast six months in normal laboratory use On line measurements might shorten operational lifetime to several months In time the response time will increase and the calibration slope decreases to the point calibration is difficult and electrode replacement is required Electrode Storage The bromide electrode may be stored for short periods of time in 1 0x10 2 M bromide solution For longer storage long...
Page 14: ... two solutions of different composition are brought into contact with one another liquid junction potentials arise Millivolt potentials occur from the inter diffusion of ions in the two solutions Electrode charge will be carried unequally across the solution boundary resulting in a potential difference between the two solutions since ions diffuse at different rates When making measurements it is i...
Page 15: ...s and you are using an electrode pair try the same routine with a working reference electrode 4 If the problem persists the standards and or reagents may be of poor quality interferences in the sample may be present or the technique may be faulty See sections Standards and Reagents Sample and Technique below 5 If another electrode is not available for test purposes or if the electrode in use is su...
Page 16: ...nces Technique Be sure that the electrode s limit of detection has not been exceeded Be sure that the analysis method is clearly understood and is compatible with the sample Refer to the instruction manual again Reread sections on GENERAL PREPARATION and ELECTRODE CHARACTERISTICS If trouble still persists call Eutech Instruments Pte Ltd at 65 6778 6876 and ask for the Customer Services Department ...
Page 17: ...olution Noisy or Unstable defective meter check meter with Readings readings shorting strap continuously or rapidly changing air bubble on membrane remove bubble by re dipping electrode electrode exposed soak electrode in to interferences bromide standard defective electrode replace electrode ISA not used use recommended ISA meter or stirrer ground meter or stirrer not grounded Drift reading sampl...
Page 18: ...bble by re dipping probe Incorrect Answer incorrect scaling of plot millivolts on the linear but calibration semi log paper axis On the log axis be curve is good sure concentration numbers within each decade are increasing with increasing concentration incorrect sign be sure to note sign of millivolt number correctly incorrect standards prepare fresh standards wrong units used apply correct correc...
Page 19: ...tions only avoid organic solvents Size 110 mm in length 12 mm in diameter 1 m cable length Storage Store in bromide solution ORDERING INFORMATION CODE NO DESCRIPTION EC BRO 03 Bromide Ion Combination Electrode epoxy body EC SCS BR1 BT Bromide Standard 0 1M NaBr EC SCS BR2 BT Bromide Standard 1 000 ppm NaBr EC ISA BR1 BT Ionic Strength Adjuster ISA 5M NaNO3 EC MIS PP Polishing Paper for the Bromide...
