United States Environmental Protection \r ^1 M^k. Agency www.epa.gov 1978 Method 279.2: Thallium (Atomic Absorption, Furnace Technique) ------- METHOD #: 279.2 TITLE: ANALYTE: INSTRUMENTATION: STORET No. Optimum Concentration Range: Detection Limit: Approved for NPDES (Issued 1978) Thallium (AA, Furnace Technique) CAS # T1 Thallium 7440-28-0 AA Total 01059 Dissolved 01057 Suspended 01058 5-100 (ig/L 1 (ig/L 1.0 Preparation of Standard Solution 1.1 Stock solution: Prepare as described under "direct aspiration method". 1.2 Prepare dilutions of the stock solution to be used as calibration standards at the time of analysis. These solutions are also to be used for "standard additions". 1.3 The calibration standard should be diluted to contain 0.5% (v/v) HNOs. 2.0 Sample Preservation 2.1 For sample handling and preservation, see part 4.1 of the Atomic Absorption Methods section of this manual. 3.0 Sample Preparation 3.1 Prepare as described under "direct aspiration method". Sample solutions for analysis should contain 0.55% (v/v) HNOs. 4.0 Instrument Parameters (General) 4.1 Drying Time and Temp: 30 sec @ 125°C 4.2 Ashing Time and Temp: 30 sec @ 400°C 4.3 Atomizing Time and Temp: 10 sec @ 2400°C 4.4 Purge Gas Atmosphere: Argon 4.5 Wavelength: 276.8 nm 4.6 Other operating parameters should be set as specified by the particular instrument manufacturer. 5.0 Analysis Procedure 5.1 For the analysis procedure and the calculation, see "Furnace Procedure" part 9.3 of the Atomic Absorption Methods section of this manual. ------- 6.0 Notes 6.1 The above concentration values and instrument conditions are for a Perkin-Elmer HGA-2100, based on the use of a 20 (iL injection, continuous flow purge gas and non-pyrolytic - graphite. Smaller size furnace devices or those employing faster rates of atomization can be operated using lower atomization temperatures for shorter time periods than the above recommended settings. 6.2 The use of background correction is recommended. 6.3 Nitrogen may also be used as the purge gas. 6.4 For every sample matrix analyzed, verification is necessary to determine that method of standard addition is not required (see part 5.2.1 of the Atomic Absorption Methods section of this manual). 6.5 If method of standard addition is required, follow the procedure given earlier in part 8.5 of the Atomic Absorption Methods section of this manual. 6.6 Data to be entered into STORET must be reported as (ig/L. 7.0 Precision and Accuracy 7.1 Precision and accuracy data are not available at this time. ------- Method 279.2 For Thallium, Method 279.2 (Atomic Absorption, Furnace Technique) replace the Precision and Accuracy Section statement with the following: Precision and Accuracy An interlaboratory study on metal analyses by this method was conducted by the Quality Assurance Branch (QAB) of the Environmental Monitoring Systems Laboratory-Cincinnati (EMSL-CI). Synthetic concentrates containing various levels of this element were added to reagent water, surface water, drinking water and three effluents. These samples were digested by the total digestion procedure, 4.1.3 in this manual. Results for the reagent water are given below. Results for other water types and study details are found in "EPA Method Study 31, Trace Metals by Atomic Absorption (Furnace Techniques)," National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 Order No. PB 86-121 704/AS, by Copeland, F.R. and Maney, J.P., January 1986. For a concentration range of 10.00-252|ig/L. X=0.8781(C)-0.715 S=0.1112(X)+0.669 SR=0.1005 (X)+0.241 Where: C=True Value for the Concentration, (ig/L X=Mean Recovery, (ig/L S=Multi-laboratory Standard Deviation, (ig/L SR=Single-analyst Standard Deviation, (ig/L ------- |