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Posts Tagged ‘chromium’

Sequential Extraction Procedure

Tuesday, June 1st, 2010

By Pradeep Divvela, Project Chemist, Kelso, WA

ShakerSequential extraction is an analytical process that chemically leaches metals out of soil, sediment and sludge samples. The purpose of sequential “selective” extraction is to mimic the release of the selective metals into solution under various environmental conditions.

One commonly used sequential extraction procedure is designed to partition different trace metals based on their chemical nature.

The sequential extraction process is typically accomplished in four (4) steps using:

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How to Determine Metals Emissions by EPA Method 29

Monday, April 26th, 2010

By Ed Wallace, Project Chemist, Kelso, WAEPA Method 29

EPA Method 29 measures hazardous air pollutant (HAP) emissions from stationary sources for mercury and other metals. The Clean Air Act (CAA) requires all major sources to meet HAP emission standards reflecting the application of maximum achievable control technology (MACT). These sources include industrial, commercial, and institutional boilers and process heaters. The other metals to be tested are antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, nickel, phosphorus, selenium, thallium and zinc.

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Hexavalent Chromium in Aqueous Samples Containing Color and Chemical Interferences

Friday, February 4th, 2005

Hexavalent-Chromium-in-Aqueous-Samples-Containing-Color-and-Chemical-InterferencesBackground
Today there are two common colorimetric techniques using a Diphenylcarbazide (DPC) solution for determining Hexavalent Chromium (Cr+6) in RCRA site water samples. EPA Method 7196, a colormetric method, analyzes the untreated or filtered sample as is. EPA Method 7199, an ion chromatographic method, separates the Cr+6 ion from interferences and is then followed by post column reaction with DPC. Therefore, colored matrices or matrices containing chemical interferences may be better analyzed by ion chromatography as shown in the following example.

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