Hi Dana,
      Your question was referred to me as I am the ATP program
coordinator.
      In section 7.3 of Method 1664, it states that the n-hexane should
be "85% minimum purity, 99.0% minimum saturated C6 isomers, residue less
than 1 mg/L."  The use of less pure n-hexane is not acceptable.  If the
lab chooses to use n-hexane of lower purity, comparative studies would
have to be conducted and accepted via the ATP program.  However, if the
lab uses purity greater than 85% for the n-hexane (i.e. 95% n-hexane),
comparative studies do not need to be conducted, since that falls within
the specifications of the method.
      I hope this is helpful to you.
      Robin.



                                                                        
             Maria                                                      
             Gomez-Taylor/DC/                                           
             USEPA/US                                                To 
                                      Marion Kelly, Robin               
             06/05/2006 04:29         Oshiro/DC/USEPA/US@EPA            
             PM                                                      cc 
                                                                        
                                                                Subject 
                                      Fw: EPA 1664 question             
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        



Can someone respond to this person?

Maria Gomez-Taylor, Deputy Director
Health and Ecological Criteria Division
Mail Code - 4304T
1200 Pennsylvania Avenue
N.W. Washington, D.C. 20460
Phone: 202-566-1005
Fax: 202-566-1140
E-mail: gomez-taylor.maria@epa.gov
----- Forwarded by Maria Gomez-Taylor/DC/USEPA/US on 06/05/2006 04:28 PM
-----
                                                                        
             Dana Satterwhite                                           
             <dana.satterwhit                                           
             e@ncmail.net>                                           To 
                                      Maria                             
             06/05/2006 04:00         Gomez-Taylor/DC/USEPA/US@EPA      
             PM                                                      cc 
                                                                        
                                                                Subject 
                                      EPA 1664 question                 
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        




Maria,
As the 85% hexane is becoming more scarce, what are the available
options for the extraction solvent for EPA Method 1664 for NPDES work?
Is the use of the lesser grade solvents (e.g., 66%) acceptable if the QC

benchmarks in the method can be achieved?
Thank you for your time,
Dana Satterwhite
(See attached file: dana.satterwhite.vcf)