Office of Ground Water and Drinking Water 

January 27, 2010

MEMORANDUM 

SUBJECT: 	Basis for Expedited Approval of Standard Methods 6640 B and
6640 B-01 for the Analysis of Dalapon

FROM: 	Glynda Smith, Chemist 

Technical Support Center 

TO: 		The Record 

This memo documents the reviews conducted on Standard Methods 6640 B and
6640 B-01 for the determination of dalapon in drinking water.  It
provides the background information on why EPA is approving these
methods using the expedited methods approval process.

Standard Method 6640 B published in the 21st edition of Standard Methods
for the Analysis of Water and Wastewater:

	EPA Method 515.4, Revision 1.0 was used as the basis for comparison
because it is currently cited in the drinking water regulations at 40
CFR 141.24(e)(1) for dalapon.  Standard Method 6640 B was developed
directly from EPA Method 515.4, Revision 1.0 and thus uses the identical
sample collection/handling protocols, sample preparation and
derivatization steps, chromatographic conditions (specifically the use
of a secondary confirmation column) and electron capture detection.  The
methods have the same quality control requirements and the method
performance data (detection levels, accuracy and precision) are
identical.  Therefore, Standard Method 6640 B is equally as effective as
EPA Method 515.4, Revision 1.0 in determining dalapon concentrations in
drinking water.

Standard Method 6640 B-01 published online at   HYPERLINK
"http://www.standardmethods.org"  http://www.standardmethods.org :

	The version published online is identical to the version published in
the 21st edition (6640 B) and thus equally effective as Method 515.4,
Revision 1.0 in determining dalapon concentrations in drinking water.

