Procedures and precautions used in sampling techniques and analysis of trace elements in plant matrices

Methods of sampling, sample preparation, sample pre-treatment and analysis of trace elements are described. Plant analysis is carried out on small samples which are taken over large areas of approximately 2 hectares. Precautions are taken to ensure that such samples are representative of the area sampled. Time of sampling and the part of the plant which is sampled is important as these affect the interpretation of the analytical data. The size of sample must be large enough to carry out whatever analyses are required. Accurate weighting and volume measurements are necessary for reliable analytical results. The total trace element which is present in the plant tissue is measured. The extraction, digestion or fusion methods which are used at the Johnstown laboratory are described. Constant room temperature must be used during analysis and the acidity or alkalinity of the solutions are adjusted as required. The methods of measuring the trace element contents in the plant extracts are described. The trace elements which are discussed are boron, manganese, copper, zinc, cobalt, selenium, iron, iodine and molybdenum. These are the trace elements which can be deficient or toxic in crops and grassland in Ireland.