EPA-EAD: 613: Qualitative confirmation and Quantification of 2,3,7,8-TCDD via GC/MS after a screen using Method 625

Summary
Analytes
Revision
Data and Sites

Official Method Name

2,3,7,8-Tetrachlorodibenzo-p-dioxin

Current Revision

40 CFR Part 136, Appendix A (Current Edition)

Media

WATER

Instrumentation

Gas Chromatography with Mass Spectrometry Detection

Method Subcategory

Organic

Method Source

EPA-EAD

Citation

EPA Method Guidance CD-ROM (includes MCAWW Methods, and most current EPA Methods)

Brief Method Summary

A 1 L sample is spiked with an internal standard of 2,3,7,8-TCDD and extracted with methylene chloride using a separatory funnel. The extract is exchanged to hexane at a concentration of 1.0 mL or less. The extract is then analyzed by capillary column GC/MS to separate and measure 2,3,7,8-TCDD.

Scope and Application

This is a GC/MS method that qualitatively confirms and quantifies the presence of 2,3,7,8-TCDD scanned using Method 625 for municipal and industrial discharges as provided under 40 CFR part 136.1.

Applicable Concentration Range

MDL to 1000xMDL (ug/L)

Interferences

(A) Glassware: Must be scrupulously cleaned. Prior to detergent washing, the glassware should be rinsed with the last solvent used and then placed in a muffle furnace to remove any thermally unstable organic compounds. Some thermally organic compounds, such as PCBs may still remain. A rinse with acetone or pesticide quality hexane may be substituted in place of the muffle furnace. Store glassware inverted or capped with aluminum foil.
(B) Co-extraction: The extraction process will sometimes extract certain analytes, such as chlorinated compounds, that may cause possible interference with the target compounds. If these compounds present interference, a cleanup procedure is described in Section 11 of the method.

Quality Control Requirements

Initial demonstration of laboratory capability and the periodic analysis of laboratory reagent blanks, fortified blanks, and other laboratory solutions as a continuing check on performance.

Sample Handling

Samples should be grabbed in 1 Liter or 1 Quart amber bottles with Teflon lined cap. Store samples away from direct sunlight. The bottles must be washed, rinsed with methylene chloride or acetone, and dried before use to minimize contamination. Samples should be iced or kept refrigerated at 4^oC from time of collection to time of extraction. If free chlorine is present, add 80 mg of sodium thiosulfate to the sample.

Maximum Holding Time

All samples must be extracted within 7 days of collection and completely analyzed within 40 days if extraction.

Relative Cost

$201 to $400

Sample Preparation Methods

None.

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
2,3,7,8-Tetrachlorodibenzo-p-dioxin(1746-01-6) 2,3,7,8-TCDD 2,3,7,8-Tetrachlorodibenzo-p-dioxin Dibenzo-p-dioxin, 2,3,7,8-tetrachloro- Dibenzo[b,e][1,4]dioxin, 2,3,7,8-tetrachloro- Dioxin Tetrachlorodibenzo-1,4-dioxin,2,3,7,8-	0.002 ug/L	90% Rec (ML)	20.00 % RSD (ML)			0.04 ug/L

Precision Descriptor Notes:	The precision and accuracy values were determined using regression equations derived from a 11 laboratory validation study. The study determined the analyte using reagent water, drinking water, surface water, and three industrial wastewaters spiked at six concentrations over the range 0.02 to 0.20mg/L.
Detection Level Note:	MDL procedure is equivalent to the procedure at 40 CFR part 136, Appendix B. MDLs were determined using the standard deviation of 7 replicate analyses of an analyte-fortified reagent water sample multiplied by the t-value for 6 degrees of freedom at the 99% confidence level (3.14). Detailed instructions for how MDLs are determined are found in Section 12.1 of the Method.

Revision	PDF/Link
40 CFR Part 136, Appendix A (Current Edition)

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EPA-EAD: 613: Qualitative confirmation and Quantification of 2,3,7,8-TCDD via GC/MS after a screen using Method 625

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