Neil, the R & S You refer to could be concerning the stereochemistry of the material in question. "R" is german for Rectus which means Right, and "S" is for Sinster which is for Left.
If this is incorrect I apologize, but this is my best guess.
Cheers!
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George D. McCallion
Chemist III
Chemical Process Research & Development
Johnson Matthey Pharmaceutical Materials
2003 Nolte Drive
West Deptford, NJ 08066-1742
Voice: 856.384.7255
Fax: 856.384.7186
E-Mail: mccalgd**At_Symbol_Here**jmusa.com
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----- Original Message -----
From: "NEAL LANGERMAN" <neal**At_Symbol_Here**CHEMICAL-SAFETY.COM>
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Sent: Wednesday, June 2, 2010 10:11:25 AM GMT -05:00 US/Canada Eastern
Subject: [DCHAS-L] R-S Phrases
Does anyone know of a source of R-S Phrases assigned to pure chemicals? Searching through MSDSs is tedious and with the growth of GHS a list is becoming important