| RMAL HOME | Techniques
The RMAL has the capability to analyze for a large number of inorganic and organic anions and cations using the following two analytical techniques:
The EPA's "Test Methods for Evaluating Solid Waste Physical/Chemical Methods" (SW846) is used as guidance for these analytical techniques. However, the RMAL has not developed in-house standard analytical methods (SAM) for these analysis. The reason for this is that typically these analysis are performed to address remediation issues or in support of engineering studies. The RMAL has had to develop methods using these techniques for analytes which are not addressed by the SW846 methods. The RMAL does however use the SW846 guidance to establish the quality assurance guidelines for these analysis techniques. These QA guidelines have been incorporated into the RMAL's quality assurance project plan document QAP-X-96-CASD/RML-001. Instruments Each instrument is either located in a radiochemical hood or interfaced with a hood system for radioactive containment. Each instrument is described below with a list of typical analytes and their detection limits. Pictures of the instruments are also included.
Ion Chromatography (IC) Type: Dionex 4500i Operation: A liquid sample is loaded into a fixed volume injection loop. When loading is complete liquid eluant is directed through the loop and transports the sample to an analytical column. The analytes are retained on the column as the liquid passes through. The the eluant, which is continually pumped through the system, competes with the analytes for the active sites on the column eventually washing them off. The weaker retained analytes are swept off the column first followed by the more strongly retained ones resulting in separation of the species of interest. As the analyte is swept off of the column it is passed through a detector whose response is proportional to its concentration. The detector response is calibrated with standards of known concentration. The RMAL has three types of detection devices (conductivity, electrochemical, and wavelength) allowing for the detection and quantitation of a large number of different analytes. Typical analytes and their
detection limits: The following is by no means an entire list of capabilities.
With the proper eluants and hardware the ion chromatograph can be easily
configured for the analysis of a large number of different analytes.
Carbon Analyzer Type: Shimadzu 5000A with a SSM 5000A solid sample module Operation: Carbon content (organic, inorganic, and total) can be determined for liquid and solid samples using the Shimadzu model TOC-5000A carbon analyzer. For solid samples a SSM-5000A solid sample module is interfaced with the TOC-5000A to determine carbon content. Each of the phases is detailed below. liquid samples Measurement of total carbon (TC) content in liquid samples is performed by introducing an aliquot of the sample via a sample injector into a combustion tube filled with oxidation catalyst heated to 680 degrees centigrade. The carbon compounds in the sample are combusted or decomposed to CO2. The CO2 combustion gas is then swept from the combustion tube using oxygen as a carrier gas via a dehumidifier and scrubber to a sample cell set in a non-dispersive infrared (NDIR) gas analyzer were the CO2 is detected. The detector output is proportional to the concentration of CO2 which in turn is proportional to the total carbon content in the sample. The total carbon concentration is obtained using a calibration curve generated by analyzing known carbon standard solutions. Measurement of total inorganic carbon (TIC) content in liquid samples is performed by introducing an aliquot of the liquid sample via a sample injector into an IC reactor vessel containing an acidic solution of dilute H3PO4. The inorganic carbon in the form of carbonates decompose to form CO2. The CO2 gas is then swept from the reactor vessel using oxygen as the carrier gas via the same path as the total carbon analysis to the NDIR. The detector output is proportional to the concentration of CO2 which in turn is proportional to the total carbon content in the sample. The total inorganic carbon concentration is obtained using a calibration curve generated by analyzing known inorganic carbon standard solutions. The total organic carbon (TOC) concentration is calculated by subtracting the TIC from the TC results. solid samples Measurement of total carbon content in solid samples is performed by weighing a portion of the sample into a ceramic boat. The boat with sample is placed into a combustion furnace containing oxidation catalyst heated to 950 degrees centigrade. The carbon compounds in the sample are combusted to form CO2 which is swept from the combustion tube to the NDIR detector using oxygen as the carrier gas. The total carbon quantification is performed by comparing the sample response to a calibration curve generated by analyzing known carbon standard solutions. Measurement of total inorganic
carbon content in solid samples is performed by weighing a portion of the
sample into a ceramic boat. The boat with sample is placed into a closed
analysis tube. Dilute H3PO4 is added to the sample then the sample is slowly
introduced into a combustion furnace heated to 250 degrees centigrade.
The inorganic carbon in the form of carbonates decompose to form CO2 which
is swept from the combustion tube to the NDIR detector using oxygen as
the carrier gas. The total inorganic carbon quantification is performed
by comparing the sample response to a calibration curve generated by analyzing
known inorganic carbon standard solutions.
The total organic carbon
(TOC) concentration is calculated by subtracting the TIC from the TC results.
Carbon detection limits: For liquid samples the detection limit is set at 1 ppm. For solid samples it is 0.1 %. |
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