Abstract: An analytical method for the independent or simultaneous determination of any number of elements selected from the group consisting of nitrogen, carbon, hydrogen and sulfur or chlorine in samples, which comprises passing an oxygen gas through a reaction tube packed with an oxidation catalyst or oxidizing agent having a heating zone of from 800.degree. C. to 1100.degree. C., introducing a sample into said tube to subject it to complete combustion, uniformalizing the gas, dividing the gas into two portions, and introducing one portion in a carrier gas into a copper-reducing tube having a heating zone of from 400.degree. C. to 700.degree. C., determining the resulting nitrogen gas, carbon dioxide gas and steam or acetylene gas on a gas detector, while introducing the second portion in an oxygen gas into an absorption liquor, and determining the resulting sulfate or chlorine ion and, an apparatus useful therefor.

Abstract: An analytical method for the determination of the total nitrogen content in aqueous systems, which comprises passing an inert gas stream containing substantially no nitrogen and carbon dioxide through a reaction tube, which is packed with a decomposition catalyst and maintained at a temperature of 700.degree. to 1200.degree. C., a condenser and a moisture-absorbing tube in this order, injecting an aqueous test sample to be analyzed into the reaction tube, and sending the gaseous products coming out of the moisture-absorbing tube to a mass spectrometer to determine the nitrogen content, and an apparatus for carrying out such a method. By this method, it is possible to determine the total nitrogen content in nitrogen compounds contained in aqueous systems, rapidly, accurately and with a high sensitivity.

Abstract: An analytical method for the determination of total nitrogen contents in samples, which comprises passing an inert gas stream containing substantially no nitrogen through a first reaction tube which is packed with a decomposition catalyst and oxidizing agent and maintained at a temperature of 700.degree. to 1100.degree. C., a condenser for condensing unnecessary components in the gaseous products from the first reaction tube, a second reaction tube which is packed with an oxidizing agent and a reducing agent and is maintained at a temperature of 400.degree. to 800.degree. C., a moisture-absorbing tube and a carbon dioxide gas-absorbing tube in this order, introducing a liquid sample to be analyzed into the first reaction tube and sending nitrogen gas coming out of the carbon dioxide gas-absorbing tube to a nitrogen gas analyzer to determine the nitrogen gas, and an apparatus for carrying out such a method.