ST. LOUIS, Sept. 11 — Sigma-Aldrich (Nasdaq: SIAL) announced today that it has entered into an exclusive agreement with IsoSciences, LLC, to distribute isotopically labeled bioactive compounds and their metabolites (http://www.sigma-aldrich.com/isotope) through its Aldrich division. IsoSciences, a leading stable isotope company, provides a wide array of biological compounds and custom synthesis products. Aldrich, provider of ISOTEC(R) Stable Isotopes, is a leader in manufacturing and providing stable isotope products for biomolecular NMR, proteomics, metabolic and MRI research.

Under the terms of the agreement, IsoSciences will be the exclusive provider to Aldrich for their stable isotope products listed in the agreement. These products include deuterated, 13C and 15N labeled vitamins, steroids, and other bioactive compounds used in metabolic research.

Nutrition and metabolic research investigates the relationships among diet, health and diseases by nutrient interactions with various metabolic pathways, bioavailability and nutrient analysis. These stable isotope products will be an addition to the extensive list of unlabeled bioactive compounds provided by Sigma-Aldrich.

“A new partnership with IsoSciences will allow Sigma-Aldrich to provide new stable isotope product lines to support our customers’ research,” said Dr. C.T. Tan, ISOTEC Stable Isotope’s R&D Manager. “This collaboration offers a new range of labeled bioactive compounds for our ever expanding customer base.”

“We have invested heavily in synthesizing difficult-to-prepare, yet vitally needed, isotopically labeled standards,” said David Saunders, President of IsoSciences, LLC.

IsoSciences’ CEO Dr. Scott W. Landvatter added, “Our partnership with Sigma-Aldrich will allow us the widest possible distribution of our unique stable isotope labeled compounds to scientists worldwide.”

About Sigma-Aldrich: Sigma-Aldrich is a leading Life Science and High Technology company. Our biochemical and organic chemical products and kits are used in scientific and genomic research, biotechnology, pharmaceutical development, the diagnosis of disease and as key components in pharmaceutical and other high technology manufacturing. We have customers in life science companies, university and government institutions, hospitals, and in industry. Over one million scientists and technologists use our products. Sigma-Aldrich operates in 36 countries and has 8,000 employees providing excellent service worldwide. Sigma-Aldrich is committed to Accelerating Customer Success through Leadership in Life Science, High Technology and Service. For more information about Sigma-Aldrich, please visit our award-winning website at http://www.sigma-aldrich.com.

About IsoSciences: IsoSciences, LLC is a leader in providing custom synthesized isotopically labeled compounds including intermediates, final drug substances, and isotopically labeled biological standards. IsoSciences works with the world’s leading pharmaceutical companies, diagnostic laboratories, medical researchers and other companies requiring stable-isotope labeled compounds for R&D. For more information about products and services offered by IsoSciences, LLC please visit http://www.isosciences.com.

Cautionary Statement: This release contains forward-looking statements relating to future performance, goals, strategic actions and initiatives and similar intentions and beliefs and other statements regarding the Companies’ expectations, goals, beliefs, intentions and the like, which involve assumptions regarding the Companies’ operations and conditions in the markets the Companies serve. The Companies do not undertake any obligation to update these forward-looking statements.

Sigma-Aldrich, Aldrich and ISOTEC are registered of Sigma-Aldrich Biotechnology L.P. and Sigma-Aldrich Co.