Determination of Nitrate in Plant Materials

Determination of ammonia and nitrate in soil

“…The only apparent objection is that the methods are subject to slight interference by glutamine, which is known to occur in plant extracts. However, the fact that the methods are applicable to coloured extracts and are not subject to interference by chloride, glucose and ascorbic acid would seem to more than compensate for this disadvantage, as numerous difficulties have been encountered in the removal of colour and chlorides from plant extracts prior to the determination of nitrate by the colorimetric procedures generally employed (see Johnson & UMch, 1950;Jones & Underdown, 1953). We have not investi-gated the suitability of the microdiffusion methods for the determination of ammonia and nitrate in plant materials but have carried out a few analyses to determine the recoveries by these methods of ammonia and nitrate added to extracts of plant materials.…”

“…Glucose and ascorbic acid. Varner, Bulen, Vanecko & Burrell (1953) recently found that glucose interfered with a reduction method for the determination of nitrate in plant materials, and Jones & Underdown (1953) found in a study of colorimetric methods for the same purpose that the phenoldisulphonic acid method was subject to slight interference by ascorbic acid. Although glucose and ascorbic acid are hardly likely to occur in soil in amounts sufficient to disturb the determination of nitrate, we considered that it would be useful to know if the microdiffusion method of determining nitrate was affected by these substances and carried out a series of analyses to test for interference.…”

“…The use of absorbents such as charcoal and oxidizing agents such as hydrogen peroxide has been proposed for the decolorization of extracts, but several workers (e.g. Sowden & Atkinson, 1949) have shown that these decolorizing procedures can lead to loss of nitrate by absorption or formation of nitrate by oxidation of nitrogenous substances in the extract.…”

Nitrogen Compounds of Cabbage. I. The Relation of the Non‐protein to the Total Nitrogen With Special Reference to the Essential Amino Acids

“…Amino-nitrogen determinations were made by the Van Slyke method with a modified auxiliary reaction chamber as used by Doherty and Ogg (11). Nitrate nitrogen was determined by the method of Jones and Underdown (23).…”

Coumarin Assay, Determination of Coumarin in the Presence of Sterols

“…Gibberellic acid is a colorless, polycyclic, unsaturated, monobasic acid containing a lactone group, having a molecular weight of 346 (3), and only end absorption in the ultraviolet region (4,6). It has no intrinsic properties which aid in its direct determination during production and purification.…”