Pakistan Research Repository

DEVELOPMENT OF A TITRIMETRIC AND A SPECTROPHOTOMETRIC METHOD FOR THE MICRO DETERMINATION OF NITRATES IN SOIL AND WATER

Haque, Qamar ul (1978) DEVELOPMENT OF A TITRIMETRIC AND A SPECTROPHOTOMETRIC METHOD FOR THE MICRO DETERMINATION OF NITRATES IN SOIL AND WATER. PhD thesis, University of Sindh, Jamshoro.

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Abstract

Two methods were developed for the determination of the nitrate ion in soil, water and other materials. The well known spectrophotometric method based on 2,4-phenoldisulphonic acid forming a complex with the accuracy and sensitivity of the new methods. Standard synthetic aqueous solutions of sodium nitrate and a batch of soil samples from some cultivated lands near Hyderabad (Pakistan) were used as materials for analysis. The colorimetric method involves modification of a known older method. The titrimetric method is a new method which is based on the qualitative test for nitrate which developes a brown colour on reduction with excess of ferrous sulphate in sulphuric acid. Spectrophotometric: sulphonated phenol-phthalein was used as a complexing reagent. A yellow colour is developed which gives a maximum at 420 nm at which wavelength all the analysis have been made. Sulphonation of phenolphthalein proceeds at room temperature in a short time and appears to be a better reagent than 2:4-phenoldisulphonic acid. The method is compable of being used in the field. The range of analysis is from 0.80 to 8/.0mg/litre. Chloride interferes. Titrimetric: The nitrate ion is reduced by an excess of ferrous sulphate which is back titrated by potassium dichromate, the end point being detected electrometrically by the dead stop titration method. The advantages of this method are easier working and better accuracy with respect to known volumetric methods for the nitrate determination. Suitable range of analysis by this method is from 5 ug to 500ug per ml. The average error is +.5%. This is also suitable for development into a method to be used in the field

Item Type:Thesis (PhD)
Uncontrolled Keywords:titrimetric method, spectrophotometric method, micro determination, nitrates, colorimetric method, sulphonation
Subjects:Physical Sciences (f) > Chemistry(f2)
ID Code:981
Deposited By:Mr. Muhammad Asif
Deposited On:23 Nov 2006
Last Modified:04 Oct 2007 21:03

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