In Reply Refer to:

Mail Stop 412  May 9, 2001


Office of Water Quality Technical Memorandum 2001.06


Subject:     Replacement of National Water Quality Laboratory Schedule 172, Determination of Trace Elements in Blank Water, with Schedule 1673




The “parts-per-billion” inorganic protocol documentation (Horowitz, 1994) and 3 Office of Water Quality (OWQ) Technical Memoranda (94.06, 94.12, and 97.03) specifically mention National Water Quality Laboratory (NWQL) Schedule 172 as the only schedule to use for inorganic trace element blank determinations.  Effective June 1, 2001 (NWQL Technical Memorandum 2001.01), the NWQL is replacing Schedule 172 with Schedule 1673.  Schedule 1673 offers additional trace elements and uses reporting limits based upon long-term method detection level (LT-MDL) procedures (Childress, 1999).  An additional advantage with this change is that blanks and environmental samples will be determined using identical analytical methodology, a plus for some study objectives. 




This memorandum documents the replacement of Schedule 172 by Schedule 1673 in documentation related to the “parts-per-billion” inorganic protocol (Horowitz, 1994 and the 3 OWQ memos mentioned above.)  Details about Schedule 1673 are available in NWQL Technical Memorandum 2001.01 and from SPiN on the NWQL web site:  The three OWQ memos and the NWQL memo are available at:




Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, T.L., and Rickert, D.A.  1994.  U.S. Geological Survey Protocol for the Collection and Processing of Surface-Water Samples for the Subsequent Determination of Inorganic Constituents in Filtered Water.  U.S. Geological Survey Open File Report 94-539.  57 p. 


OWQ Technical Memorandum 94.06.  New Custom Analysis Schedule (172) for Blanks.


OWQ Technical Memorandum 94.12.  Change in Schedule 172. 


OWQ Technical Memorandum 97.03.  Protocols for Cleaning a Teflon Cone Splitter to Produce Contaminant-Free Subsamples for Subsequent Determinations of Trace Elements. 


NWQL Technical Memorandum 2001.01.  Elimination of National Water Quality Laboratory Blank Schedule 172. 


Childress, C.J. Oblinger, Foreman, W.T., Connor, B.F., and Maloney, T.J.  1999.  New Reporting Procedures Based on Long-Term Method Detection Levels and Some Considerations for Interpretation of Water-Quality Data Provided by the
U.S. Geological Survey National Water Quality Laboratory.  U.S. Geological Survey Open File Report 99-193.  19p. 




Kathy Fitzgerald, OWQ, ( can discuss the inorganic sample collection protocol. 


Mark Burkhardt, Chief, Analytical Services, NWQL, ( can describe Schedule 1673.





Janice R. Ward

Acting Chief, Office of Water Quality


This memorandum supersedes those parts of OWQ Technical Memoranda 94.06, 94.12, and 97.03 that refer to Schedule 172.


Distribution:  All WRD Employees