摘要:
Methods and apparatus (FIG. 4a) are disclosed for selective and very sensitive detection of certain hydrolyzable compounds, especially urea, in water by hydrolyzing said hydrolyzable compounds in a sample of the water to one or more carbon dioxide group compounds and determining the difference in the carbon dioxide content of the water and the hydrolyzed sample using conductivity measurements or other carbon dioxide detector outputs.
摘要:
This invention provides for an analytical apparatus for serial determination of nitrogen in samples by the Kjeldahl method, characterized in that it comprises from 4 to 7 flasks suspended vertically in a rotatable roundabout, each provided with a cover and a side tube extending into a common central container for the collection of combustion products, the roundabout being connected to a device which at regular intervals turns the roundabout one step forward to the next position, means for heating the flasks in one or two of the positions, means for blowing cooling air against the flasks, means for feeding diluent water to the flasks in a following position, means for introducing neutralising chemicals, means for generating and feeding steam to the flasks in the next following position, means for collecting and titrating the distillate, blowing means for emptying the flasks in the last position, and means for opening the covers on completion of the decomposition and for introducing diluent water into the flasks.
摘要:
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 NO2 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.
摘要:
A process is claimed for the determination of nitrogen content in a nitrogen containing material, said process comprising: a) at least one pre-treatment step, b) at least one distillation step and c) at least one determination step; wherein said distillation step (a) comprises the substeps of: i) diluting a pre-treated sample of a nitrogen containing material with at least one diluting fluid, ii) inputting steam for commencement of steam distillation, and iii) adding at least one alkali compound, whereby the addition of alkali is made 1-60 seconds after commencement of said inputting of steam and said steam distillation and whereby distillate produced during said steam distillation is recovered in an acidic and/or complexing medium.
摘要:
A microwave-based apparatus for rapid digestion of a sampel by a Kjeldahl method is provided which includes a reaction vessel surrounded by an insulator in the form of, for example, a cup. The reaction vessel is disposed in the internal chamber of a microwave system, which includes a wall having an aperture. A connector tube is slidably disposed in the aperture, wherein one end of the tube is connected to the mouth of the reaction vessel, and the other end is connected to a suction device external to the chamber. A biasing element is provided outside the chamber to assist in joining the slidable connector tube to the mouth of the vessel, yet enabling removal of the vessel from the chamber without detachment of the biasing element.
摘要:
A rapid, microwave-based Kjeldahl digestion method wherein microwave energy is applied to an acid/sample mixture at the beginning of, and thereafter during the digestion. After the application of microwave energy is discontinued, the digestate is diluted by pulsed addition of water, followed by continuous addition of water. Dilution in this manner prevents a sudden surge in gas evolution, and eliminates the need for an intervening cooling step, thereby reducing processing time. Also provided is a method for fat separation from a fat-containing protein sample during the digestion.