Full Description

The National Chromium and Boron Occurrence Survey(NCBOS) specifically addressed the following questions:What are the analytical method challenges and sensitivities for reliable low-leveldetection of chrome species and boron in drinking water supplies;What are the national occurrence patterns for chromium species and boron indrinking water sources; and,What is the fate of these compounds through drinking water facilities anddistribution systems? This project investigated analytical challenges for both chromium and boron analysis.The investigation focused on interferences, preservation techniques, and digestion methods foraccurate and repeatable recovery performance. Laboratory experiments were first used toinvestigate the analytical challenges. Preliminary field sampling based on knowledge gainedfrom the laboratory experiments validated the analytical methods used for the regular survey.Interferences in boron analysis were found with aluminum and iron for at least onespectrum evaluated when background concentrations approached 100 mg/L as either Fe or Al.Therefore at least two spectra were used to confirm all boron analyses. Boron was found to beotherwise unaffected by sample handling and processing methods as long as base preservationmethods were employed (pH 8).Sampling for chromium necessitated consideration of both total chromium andhexavalent chromium analyses. Previous field sampling experiences had resulted in totalchromium concentrations less than corresponding hexavalent chromium concentrations (Eaton etal. 2001). A series of lab experiments were conducted to determine the best approach forchromium analysis to correctly quantify both hexavalent and total chromium.Using in-bottle acid digestion procedures that follow Method 3500-Fe B (StandardMethods 1998) - the hydroxylamine digestion for iron solublization - was found to perform bestin achieving complete recovery of total chromium. Base preservation for hexavalent chromiumwas found to be adequate when the sample pH was raised above pH 8.The final survey sample kit preservation, digestion procedures, and sample analysisprocedures were developed based on results from the investigation of both chromium and boronanalytical challenges. Includes 4 references, tables, figures.

Product Details

Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 11File Size: 1 file , 350 KB