Laserfiche WebLink
7 <br /> 4.6 Vol is flask: 2-Liter. <br /> 4.7 Volumetric flask: 1-Liter. <br /> r 5.0 REAGENTS <br /> 5.1 ASTM T II water (ASTM D1193) : Water should be monitored tored for <br /> 5.2 Primare standard buffer salts are available from the National Burea <br /> of Standards NBS and shoo be use in situati u <br /> necessary. Preparation of reference solutions from these saltsmrequiresaccuracsois <br /> me <br /> special precautions and handling, such as low-conductivity dilution water <br /> drying ovens, and carbon-dioxide-free purge gas. These solutions should be <br /> replaced at least once each month. <br /> 5.3 Secondary standard buffers may be <br /> Y prepared <br /> purchased as solutions from NBS salts or <br /> from commerciia vendors. These commercially available <br /> solutions, which have been validated by comparison with NBS <br /> recommended for routine use. standards, are <br /> 5.4 Stock calcium chloride solution CACI 3. <br /> CaCl2.2H2O in Type II water in a 2- iter volumetric flask. Dissolve 1059 g of <br /> dilute it to volume with Type II water, and mix it well . Dilute Cool the solution20 mL of ' <br /> solution to 1 liter with Type II water in a volumetric flask and s <br /> it by titrating a 25-mL aliquot of the diluted solutio with standard standardize <br /> AgNO3, using 1 mL of 5% K2CrO4 as the indicator. <br /> 5.5 Calcium chloride (CaC12) , ®, <br /> M: Dilute 50 mL of stock 3.6 M C 12 <br /> to 18 liters with Type II water. If the <br /> the pH of this solution is not between 5 <br /> and 6.5, adjust the pH by adding a little Ca(OH)2 or HC1 . As a check on the <br /> preparation of this solution, measure its electrical conductivity. The speci- <br /> fic conductivity should be 2.32 + 0.08 mmho per cm at 256C. <br /> 6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING <br /> 6.1 All samples must be collected using a sampling plan that addr <br /> the considerations discussed in Chapter Nine of this manual . asses <br /> 6.2 Samples should be analyzed as soon as possible. <br /> 7.0 PROCEDURE <br /> 7.1 Calibration: <br /> 7.1'.1 Because of the wide variet of <br /> detailed operatin Y pH meters and accessories, <br /> g procedures cannot be incorporated into this method. <br /> Each analyst must be acquainted with the operation of each system and <br /> familiar with all instrument functions. Special attention to care of the <br /> electrodes is recommended. <br /> 9045 — 2 <br /> Revision 0 • • <br /> Date Septem er 1986 <br />