What are the primary operating modes?
The mole and the International System of Units (SI)

In an attempt to overcome the shortcomings of chemistry as a separate field of metrology, the CCQM created the concept of primary methods of analysis at its first meeting in 1993. In practice, the number of methods meeting this definition is very limited. They are essentially :

• for gaseous analytical chemistry, the static gravimetric method, the dynamic gravimetric method ;

• for inorganic analytical chemistry, the isotope dilution method (coupled with an ICP/MS), the titrimetric method and the gravimetric method;

• for organic analytical chemistry, the isotope dilution method (coupled with GC/MS).

If we consider that chromatographs account for over 80% of the world's instruments, we still have some way to go before routine methods are linked...