User manual HANNA INSTRUMENTS PL 100

[. . . ] PL 100 / PL 101 Amperometric Chlorine Titrators Instruction Manual Dear Customer, Thank you for choosing a Hanna Product. This instruction manual has been written for the following products: PL 100 Free Chlorine Titrator PL 101 Total Chlorine Titrator Both the instruments have features such as recorder outputs, 12VDC power supply for safety and reduction of EMI and built-in stirrer. Please read this instruction manual carefully before using the instrument. It will provide you with the necessary information for the correct use of the instrument, as well as a precise idea of its versatility. [. . . ] Note: If the pH of the sample is between 6. 0 and 7. 5 it is not necessary to add the buffer. Turn on the speed controlled stirrer and place the beaker on the top of the PL 100. Immerse the probe tip into the sample, make sure the platinum electrodes are submerged. 7. Adjust the potentiometric setting, using the " " and " " keys on the front panel until the display reads about 1. 00. 15 8. Dispense the titrant into the beaker in small increments. Note the downward reading on the amperometric titrator. Record the display reading that corresponds exactly to the mL of the titrant added. Record at least 3 points before and 3 points after the End Point. Construct a titration graph using the PL 100 graph paper. 10. Draw the best-fit line through each set of points. The end point is determined by the intersection of the two best lines through the points. 11. Read directly the free chlorine concentration on the top of the graph by drawing a straight vertical line through the End Point or read the volume of titrant used until the End Point and multiply by 2 when titrant (a) 0. 00564N PAO is used or multiply by 0. 2 when titrant (b) 0. 000564N PAO is used. mL(till End Point) x 2(or 0. 2) = mg/L Free Cl2. Method B: Total Chlorine Forward Titration (PL 101 only) 1. Fill the bottle of the automatic burette with 0. 000564N PAO solution (HI 70471) for titrations up to 1500µg/L Cl2 or use the 0. 00564N PAO solution (HI 70466) for titrations up to 15000µg/L Cl2. Fill the 10 mL automatic burette to the zero mark. Use a 100 mL volumetric pipet to transfer 100mL of sample to a 250 mL beaker and add about 100 mL chlorine free water. Add one spoon of potassium iodide from the bottle (HI 70468) and swirl to dissolve. Add 1 mL of pH 4 acetate buffer solution (HI 70467) into the beaker. Turn on the speed controlled stirrer and place the beaker on the top of the PL 101. 16 6. Immerse the probe tip into the sample, make sure the platinum electrodes are submerged. 7. Adjust the potentiometric setting, using the " " and " " keys on the front panel until the display reads about 1. 00. [. . . ] PROBE CONDITIONING When the probe has not been used for some time (one week) or it is new, it is recommended that it be conditioned as follows: 1. Add a few drops of bleach to tap water in a 250 mL beaker and place the stir bar in the beaker. Place the beaker on the PL 100/PL 101, turn on the instrument and the stir motor. Immerse the probe in the solution, adjust the digital potentiometer for a current of 0. 5 to 1. 5 µA, and leave for ten minutes. [. . . ]