Method and apparatus for determining the nitric oxide content of a sample gas stream. The nitric oxide in the gas stream is reacted with an excess amount of ozone so as to completely convert the nitric oxide into nitrogen dioxide. The resulting gas containing nitrogen dioxide and residual ozone is passed through a scrubber which removes the ozone and does not affect the nitrogen dioxide content of the gas. The resulting gas is then analyzed for its NO.sub.2 content, which is a function of the nitric oxide content of the sample gas. The method and apparatus may also be utilized for determining the total amount of nitrogen dioxide and nitric oxide in a sample gas. The invention is particularly applicable to the monitoring of air for air pollution control.
An apparatus for determining the amount of mercury in a liquid or gas sample is provided comprising means for sequentially oxidizing and reducing a non-organic fluid containing mercury combined with organic molecules to form mercury metal and means for passing an inert gas to carry said mercury metal to a UV spectrophotometer wherein the amount of mercury is recorded.
An NO.sub.x analyzer capable of reducing maintenance operations for removing solid substances from the analyzer, and for obtaining an analytical value of improved reliability for sample gases flowed through the analyzer is provided. A sample gas supply passage on the downstream side of an NO.sub.x convertor is provided with a first capillary therein; a sample gas supply passage between the first capillary and the NO.sub.x convertor is provided with an overflow passage having a second capillary branch connected therewith; a sample gas supply passage on a downstream side of the first capillary is provided with a diluent air supply passage having a third capillary therein and also branch connected with the sample gas supply passage. At least the confluence of the first capillary, the second capillary, and the diluent supply passage with the sample gas supply passage is arranged within a heating zone of the NO.sub.x analyzer.
In a sulfur dioxide fluorescence analyzer, a method and apparatus for eliminating the fluorescence effects of nitric oxide is disclosed wherein a sample gas is mixed with a diluent which substantially quenches nitric oxide fluorescence.
The method of converting nitrogen dioxide to nitric oxide which includes maintaining the nitrogen dioxide at a temperature from about 40.degree.C to about 130.degree.C. The nitrogen dioxide is exposed to ultraviolet radiation, whereby the nitrogen dioxide is converted to nitric oxide. A method of measuring nitrogen dioxide utilizing this conversion is also disclosed.
An analytical method for determining the elemental carbon and nitrogen contents of a sample. The sample, as a liquid or in finely divided solid form is placed in an evacuable pressure vessel and is then oxidized with a cupric oxide oxidizing agent to convert carbon to CO.sub.2, nitrogen to N.sub.2, and hydrogen to water. After cooling to condense the water, the resulting pressure provides a measure of the total carbon plus nitrogen content of the original sample. An aliquot of the gas is then treated for CO.sub.2 removal, and the resulting change in volume thereby provides a measure of the ratio of carbon to nitrogen in the original sample.
