Nitrogen, quantitative determination,

A iridine traces in aqueous solution can be determined by reaction with 4-(p-nitroben25l)pyridine [1083-48-3] and potassium carbonate [584-08-7]. Quantitative determination is carried out by photometric measurement of the absorption of the blue dye formed (367,368). Alkylating reagents interfere in the determination. A iridine traces in the air can be detected discontinuously by absorption in Folin s reagent (l,2-naphthoquinone-4-sulfonate) [2066-93-5] (369,370) with subsequent chloroform extraction and hplc analysis of the red dye formed (371,372). The detection limit is ca 0.1 ppm. Nitrogen-specific thermal ionisation detectors can be used for continuous monitoring of the ambient air. 

Another analytic procedure based on HPLC has been developed for the quantitative determination of nitrogen-containing corrosion inhibitors [1194]. The method was primarily developed for the analysis of certain oil pipeline condensate samples. 

The specific surface area of the fresh and used catalysts was measured by nitrogen adsorption method (Sorptometer 1900, Carlo Erba Instruments). The catalysts were outgassed at 473 K prior to the measurements and the Dubinin equation was used to calculate the specific surface area. The acidity of investigated samples was measured by infrared spectroscopy (ATI Mattson FTIR) by using pyridine (>99.5%, a.r.) as a probe molecule for qualitative and quantitative determination of both Bronstcd and Lewis acid sites (further denoted as BAS and LAS). The amounts of BAS and LAS were calculated from the intensities of corresponding spectral bands by using the molar extinction coefficients reported by Emeis (23). Full details of the acidity measurements are provided elsewhere (22). 

De la Torre, R. et al. 1998. Quantitative determination of tricyclic antidepressnts and their metabolites in plasma by solid phase extraction (bond-elut TCA) and separation by capillary gas chromatography with nitrogen-phosphorus detection. Ther Drug Monit. 20 340. 

Quantitative Determination. Hie determination is earned out as described under Acid Sulphuric, lumiing. free from nitrogen. 

Sample for either qualitative or quantitative determinations (see Basic Protocol 2) Liquid nitrogen... 

Methanol. After oxidation, the alkaline reaction mixture was distilled under oxygen-free nitrogen under reduced pressure (approx. 150 mm. Hg). The receiver was cooled to —15° to — 10°C. using a cooling mixture (ethanol-dry ice). The distillate was analyzed by vapor phase chromatography following a procedure developed by Machata (19) for quantitatively determining blood alcohol. 

The quantitative determination of amperozide in plasma using MALDI-MS was demonstrated (Jespersen et al., 1995). This study required addition of a stable-isotope-labeled amperozide as an internal standard and a typical liquid-liquid extraction procedure with dry down and reconstitution. The sample was then mixed with the matrix and analyzed. Linearity was achieved over a range of 2.5-40 [iM. Other examples have been demonstrated (Duncan et al., 1993) which also required the use of stable-isotope analogs as internal standards. These examples also utilized TOF instruments with nitrogen lasers. 

Several such instruments have been developed for the simultaneous determination of carbon, hydrogen, and nitrogen in various samples. Of course, basic requirements for the instruments are that they provide for the complete conversion of carbon, hydrogen, and nitrogen in coal to carbon dioxide, water vapor, and elemental nitrogen, and for the quantitative determination of these gases in an appropriate gas stream. 

Morrison, M. E., Rinker, R. G., Corcoran, W. H. Quantitative determination of parts-per-million quantities of nitrogen dioxide in nitrogen and oxygen by electron capture detection in gas chromatography. Anal. Chem. 36, 2256 (1964). 

Lee and Stokker [161] have developed a multi-residue procedure for the quantitative determination of 11 triazines in non saline waters by a gas chromatographic method using a nitrogen-phosphorus detector. Ametryne, Atraton, Atrazine, Cyanazine, Prometron, Prometryne, Propazine, Simazine, Simetone and Simetryne were used. All of them could be successfully quantified on both the Ultrabond 20m and 3% OV-1 columns. Extraction was by methylene chloride and clean-up on Florasil. Recoveries of triazines at 10, 1.0... 

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