User manual EUTECH INSTRUMENTS AMMONIUM EPOXY

[. . . ] Instruction Manual Ammonium Electrode EUTECH INSTRUMENTS PTE LTD. AMMONIUM ION ELECTRODE INSTRUCTION MANUAL GENERAL INSTRUCTIONS Eutech Instruments Ammonium Ion Electrode is used to measure ammonium ions in aqueous solutions in a more simple, quick, accurate, and economical manner. Required Equipment 1. 2. A pH/mV meter or an ion meter, either line operated or portable. Semi-logarithmic 4-cycle graph paper for preparing calibration curves when using the meter in the mV mode. 2. Deionized or distilled water for solution and standard preparation. [. . . ] Dilute 1 ml of the 0. 1M standard to 100 ml to prepare a 1. 0x10-3M standard solution for measurements in moles per liter. Dilute 10 ml of the 1, 000 ppm standard to 100 ml to prepare a 100 ppm standard solution for measurements in ppm. To a 150 ml beaker, add 100 ml of distilled water and 1 ml of low level ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate. Add increments of the 1. 0x10-3M or 100 ppm standard as given in Table 2 below. After the reading has stabilized, record the mV reading after each addition. TABLE 2: Stepwise Calibration for Low Level Ammonium Measurements Added Concentration Volume (ml) M ppm -6 0. 1 0. 1 1. 0X10 0. 1 2. 0X10-6 0. 2 -6 0. 2 4. 0X10 0. 4 0. 2 6. 0X10-6 0. 6 -6 0. 4 9. 9X10 1. 0 2 2. 9X10-5 2. 9 -5 2 4. 8X10 4. 8 3. 4. A 1oC difference in temperature results in a 2% error at the 1. 0X10-3M level. Provided that temperature equilibrium has occurred, the ammonium ion electrodes can be used at temperatures from 0o-50oC continuously and 40o-50oC intermittently. Room temperature measurements are recommended, since measurements at temperatures markedly different from room temperature may require equilibrium times up to one hour. Table 4 indicates the variation of theoretical slope with temperature. TABLE 4: Temperature vs Value for the Electrode Slope Temp (oC) 0 10 20 25 30 40 50 S"(slope) 54. 20 56. 18 58. 16 59. 16 60. 15 62. 13 64. 11 8 Instruction Manual Ammonium Electrode Electrode Response Plotting the electrode mV potential against the ammonium concentration on semi-logarithmic paper results in a straight line with a slope of about 56 mV per decade. The time needed to reach 99% of the stable electrode potential reading, the electrode response time, varies from one minute or less for ammonium concentration above 1. 0X10-5M to several minutes near the detection limit. Refer to Figure 2. Electrode Storage The ammonium ion electrode may be stored in 1. 0X10-2M ammonium standard for short periods of time. For storage over 3 weeks, rinse and dry the ammonium membrane electrode and cover the tip with any protective cap shipped with the electrode(s). The reference portion of the combination electrode (or the outer chamber of the reference electrode) should be drained of filling solution, if refillable, and the rubber insert placed over the filling hole. Detection Limit The upper limit of detection is 1M in pure ammonium chloride solutions. The upper limit of detection is above 1. 0X10-1M when other ions are present, but the possibility of a liquid junction potential developing at the reference electrode and the "salt extraction effect" are two limiting factors. Some salts may be extracted into the electrode membrane at high salt concentrations causing deviation from theoretical response. Calibrate the electrode at four or five intermediate points, or dilute the sample, to measure samples between 1. 0X10-1M and 1M. The slight water solubility of the ion exchanger in the sensing module, which causes deviation from theoretical response, determines the lower limit of detection. The theoretical response at low levels of ammonium chloride compared to actual response is shown in Figure 1. A low level measurement is recommended if ammonium measurements are made below 1. 0X10-5M (0. 18 ppm as ammonium). 9 Ammonium Electrode Instruction Manual pH Effects Hydrogen ion interferes with measurements of low levels of ammonium ion although the electrode can be used over a wide pH range. [. . . ] 4 Direct Measurement of Ammonium (using an ion meter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Low Level Ammonium Determination (using a standard pH/mV meter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Low Level Ammonium Determination (using an ion meter). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 ELECTRODE CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ]