Abstract: Methods are provided for conducting chemical analyses by combusting a sample in a combustion tube. A primary combustion chamber receives and combusts a sample to form first combustion products. A secondary combustion chamber receives and combusts the first combustion products to form second combustion products. The secondary chamber is disposed around the primary chamber and comprises a plurality of—preferably, three—combustion compartments. Each successive compartment is disposed around the preceding compartment and defines a respective gas flow channel having an inlet opening and an outlet opening at opposite ends. Each successive gas flow channel shares its inlet opening with the outlet opening of the preceding channel. The plurality of combustion compartments define a substantially continuous gas flow conduit from the inlet opening of the innermost compartment to the outlet opening of the outermost compartment. Static gas mixers may be employed to enhance mixing of the combustion products.

Abstract: Combustion tube (100,130,150) and method for combusting a sample to form combustion products for analysis. A primary combustion chamber (102) receives and combusts a sample to form first combustion products. A secondary combustion chamber (110) receives and combusts the first combustion products to form second combustion products. The secondary chamber is disposed around the primary chamber and comprises a plurality of—preferably, three—combustion compartments (112-116). Each successive compartment is disposed around the preceding compartment and defines a respective gas flow channel having an inlet opening (108,118,120) and an outlet opening (118,120,122) at opposite ends. Each successive gas flow channel shares its inlet opening with the outlet opening of the preceding channel. The plurality of combustion compartments define a substantially continuous gas flow conduit from the inlet opening of the innermost compartment to the outlet opening of the outermost compartment.

Abstract: Combustion tube (100,130,150) and method for combusting a sample to form combustion products for analysis. A primary combustion chamber (102) receives and combusts a sample to form first combustion products. A secondary combustion chamber (110) receives and combusts the first combustion products to form second combustion products. The secondary chamber is disposed around the primary chamber and comprises a plurality of—preferably, three—combustion compartments (112-116). Each successive compartment is disposed around the preceding compartment and defines a respective gas flow channel having an inlet opening (108,118,120) and an outlet opening (118,120,122) at opposite ends. Each successive gas flow channel shares its inlet opening with the outlet opening of the preceding channel. The plurality of combustion compartments define a substantially continuous gas flow conduit from the inlet opening of the innermost compartment to the outlet opening of the outermost compartment.

Abstract: The present invention relates to compositions comprising mixtures of two enantiomeric forms of diacyl tartaric anhydride and mixtures obtainable by reacting an organic compound with a mixture comprising two enantiomeric forms of diacyl tartaric anhydride. The invention also relates to a method for the preparation of such enantiomeric mixtures, starting from a mixture comprising D-tartaric acid and L-tartaric acid. The method involves reacting tartaric acid with a fatty acid anhydride under dielectric heating conditions.