Method for Combustion Analysis of Samples in a Combustion Analyzer

Abstract

A method for combustion analysing a sample in a combustion analyzer ( 120,160,180 ) is provided, where the sample comprises a proportion of sulphur. The sample is supplied to the combustion analyzer and combusted to produce combustion products, comprising a yield of sulphur dioxide for detection. Nitrogen monoxide or a source of nitrogen monoxide is supplied to the combustion analyzer to improve the yield of sulphur dioxide in the combustion products. The yield improver may be supplied before and/or during the combusting step. A proportion of yield improver is preferably greater than the (expected) proportion of sulphur. Ozone may be supplied to the combustion products to convert at least a proportion of any nitrogen monoxide in the combustion products to nitrogen dioxide, before detection.

What is claimed is: 
     
         1 . A method of combustion analysing a sample in a combustion analyzer, the sample comprising a proportion of sulphur, the method comprising the steps of:
 supplying the sample to the combustion analyzer; and   combusting the sample to produce combustion products, the combustion products comprising a yield of sulphur dioxide for detection,   characterised by the step of supplying a yield improver to the combustion analyzer, wherein the yield improver is nitrogen monoxide or a source of nitrogen monoxide.   
     
     
         2 . The method of  claim 1 , further comprising the step of detecting an amount of sulphur dioxide in the combustion products, wherein the step of supplying the yield improver takes place before the detecting step. 
     
     
         3 . The method of  claim 1 , wherein the step of supplying the yield improver takes place before the combusting step. 
     
     
         4 . The method of  claim 1 , wherein the step of supplying the yield improver takes place (additionally or alternatively) during the combusting step. 
     
     
         5 . The method of  claim 1 , wherein the yield improver is added to the sample either before or during its supply to the combustion analyzer. 
     
     
         6 . The method of  claim 1 , wherein the combustion analyzer comprises a combustion chamber in which the combusting step takes place, and the yield improver is (additionally or alternatively) supplied to the combustion chamber via a dedicated yield improver inlet. 
     
     
         7 . The method of  claim 1 , wherein the combustion analyzer comprises a combustion chamber in which the combusting step takes place and an oxygen supply inlet port to the combustion chamber for supplying oxygen thereto, and the yield improver is provided to the combustion chamber with the oxygen supply. 
     
     
         8 . The method of  claim 1 , wherein the combustion analyzer comprises a combustion chamber in which the combusting step takes place and a carrier gas supply inlet port to the combustion chamber for supplying a carrier gas thereto, and the yield improver is provided to the combustion chamber with the carrier gas supply. 
     
     
         9 . The method of  claim 1 , wherein the source of nitrogen monoxide is one or more of pyridine, benzonitrile, nitrogen dioxide, nitrogen oxides (NO x ), ammonia, and 2-ethylhexyl nitrate. 
     
     
         10 . The method of  claim 1 , wherein the source of nitrogen monoxide is any form of nitrogen compound. 
     
     
         11 . The method of  claim 1 , wherein the yield improver is supplied to the combustion analyzer such that a proportion of yield improver is greater than the proportion of sulphur. 
     
     
         12 . The method of  claim 11 , wherein the proportion of yield improver to the proportion of sulphur is greater than 2 to 1. 
     
     
         13 . The method of  claim 11 , wherein the proportion of yield improver to the proportion of sulphur is greater than 4 to 1. 
     
     
         14 . The method of  claim 11 , wherein the proportion of yield improver to the proportion of sulphur is up to 25-50 to 1. 
     
     
         15 . The method of  claim 11 , wherein the proportion of yield improver to the proportion of sulphur is up to 5 to 1. 
     
     
         16 . The method of  claim 11 , wherein the proportion of sulphur is an expected proportion of sulphur. 
     
     
         17 . The method of  claim 1 , further comprising the step of supplying ozone to the combustion products to convert at least a proportion of any nitrogen monoxide in the combustion products to nitrogen dioxide. 
     
     
         18 . The method of  claim 17 , further comprising the step of detecting an amount of sulphur dioxide in the combustion products, wherein the step of supplying ozone takes place between the combusting step and the detecting step.