Laserfiche WebLink
<br />5.4 Selenium standard stock solution (1,000 mg/L): ith r procure a <br />certified aqueous standard from a supplier and verify by comparison with a second <br />standard, or dissolve 0.3453 g of selenious acid (actual assay 94.6% H~SeO~, <br />analytical reagent grade) or equivalent in Type II water and dilute to 200 mL. <br />5.5 Nickel nitrate solution (5%): Dissolve 24.780 g of ACS reagent grade <br />Ni(N03)Z•6Hz0 or equivalent in Type II water and dilute to 100 mL. <br />5.6 Nickel nitrate solution (1%): Dilute 20 mL of the 5% nickel nitrate <br />to 100 mL with Type [[ water. <br />5.7 Selenium workinu standards: Prepare dilutions of the stock solution <br />to be used as calibration standards at the time of the analysis. Withdraw <br />appropriate aliquots of the stock solution, add 1 mL of concentrated HN03. 2 mL <br />of 30% HzOz, and 2 mL of the 5% nickel nitrate solution. Dilute to 100 mL with <br />Type II water. <br />5.8 Air: Cleaned and dried through a suitable filter to remove oil, <br />water, and other foreign substances. The source may be a compressor or a <br />cylinder of industrial-grade compressed air. <br />5.9 Hvdrooen: Suitable for instrumental analysis. <br />6.0 SAMPLE COLLECTION, PRESERVATION. AND HANDLING <br />6.1 All samples must have been collected using a sampling plan that <br />addresses the considerations discussed in Chapter Nine of this manual. <br />6.2 All sample containers must be prewashed with detergents, acids, and <br />Type II water. Plastic and glass containers are both suitable. <br />6.3 Special containers (e.g., containers used for volatile organic <br />analysis) may have to be used if very volatile selenium compounds are to be <br />'. analyzed. <br />6.4 Aqueous samples must be acidified to a pH of <2 with nitric acid. <br />6.5 Nonaqueous samples shall be refrigerated, when possible, and analyzed <br />as soon as possible. <br />7.0 PROCEDURE <br />7.1 Sample Rreoaration: Aqueous samples should be prepared in the manner <br />described in Steps 7.1.1 to 7.1.3. Sludge-type samples should be prepared <br />according to Method 3050. The applicability of a sample-preparation technique <br />to a new matrix type must be demonstrated by analyzing spiked samples and/or <br />relevant standard reference materials. <br />7740 3 <br />CD-ROM Revision D <br />Date September 1986 <br />