Determination of nitrate‐n in plants by an improved extraction procedure adapted for ultraviolet spectrophotometry

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Abstract
An analytical procedure for the ultraviolet spectrophoto‐metric determination of nitrate‐N in plant material over the range 8–15 000 mg kg‐1 is described. Plant material is extracted with 0.025 M Al2(SO4)3 and oxidised activated charcoal and after filtering, the extract is treated with the same amount of oxidised activated charcoal. Correction for interfering organic ions which remain after treatment, is made by adjusting the absorbance at 225 nm by an estimate of the background interference determined from the absorbance value at 255 nm. The net absorbance at 225 nm is used to determine nitrate‐N concentration.