Whatman filter papers contain inorganic nitrogen impurities (NH4, NO3 and NO2-N) which could introduce an error into the analysis of coal mine soils. The levels of inorganic nitrogen in the filter paper were found to be 3.1 to 5.3 mg of NH4-N and 12.1 mg of NO3-N/kg of filter paper. In order to minimise the effects of inorganic nitrogen contained in the filter papers, it is necessary to wash them with 0.5 M H2SO4, rinse them with deionised water and dry them prior to use for filtration.


MUSHK I ALAM ,M Q KHAN ,S H SHAH ,