 ## ISOGEOCHEM@LIST.UVM.EDU

#### View:

 Message: [ First | Previous | Next | Last ] By Topic: [ First | Previous | Next | Last ] By Author: [ First | Previous | Next | Last ] Font: Proportional Font  LISTSERV Archives  ISOGEOCHEM Home  ISOGEOCHEM June 2008

Subject: Re: delta conversion equation

From: yixiangchen <[log in to unmask]>

Reply-To: Stable Isotope Geochemistry <[log in to unmask]>

Date: Fri, 13 Jun 2008 09:23:12 +0800

Content-Type: text/plain

Parts/Attachments:  text/plain (1 lines)
 ```By definition, d sa/st =(Rsa/Rst-1)*1000, then Rsa/Rst =1+(d sa/st)/1000, where R is the stable isotope ratios of certain element in sa and st. As d sa/st =(Rsa-Rst)/Rst*1000=((Rsa-Rws) -(Rst-Rws))/Rst*1000, which equals to (Rsa-Rws)/Rws*(Rws/Rst)*1000+(Rws-Rst)/Rst*1000. Because Rws/Rst=1+(d ws/st)/1000, as stated above, so the result is derived ...... Paul Chen(Graduate student) Department of Earth and Space Sciences, USTC(University of Science and Tecnology of China) [log in to unmask] ----- Original Message ----- From: "Andrew Schauer" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, June 13, 2008 12:00 AM Subject: [ISOGEOCHEM] delta conversion equation > Hi all, > > An equation for converting from a working standard scale to an international reference material scale is: > > d sa/st = d sa/ws + d ws/st + 10^-3(d sa/ws * d ws/st) > > where d is the delta, sa is a sample, st is the international reference material, ws is the working standard, and sa/ws is a sample relative to a working standard. This equation is found many places (e.g. W.A Brand's chapter 38 (p855) in Handbook of Stable Isotope Analytical Techniques (ed. P.A. de Groot)). My question is, what is the derivation of the final term: > > 10^-3(d sa/ws * d ws/st) > > The term clearly deals with those samples and standards that are very different from one another, as it is larger the more disparate samples and standards are. Searching the IsoGeoChem archives shows that many folks leave off this term. Thank you all for your help. > > andy > > > > Andrew Schauer > ISOLAB > Department of Earth and Space Sciences > University of Washington > Seattle, WA 98195 > > > 206.543.6327 > [log in to unmask] >```

Advanced Options

#### Options  Log In  Get Password  Search Archives  Subscribe or Unsubscribe