Pretreatment of plant and soil samples a problem in boron analysis

Abstract

Abstract Possible sources of errors in the determination of boron in plant samples were examined. This paper will first describe some general features and then the following steps in the pre‐treatment of plant samples: Drying Grinding Dry ashing, effects of temperature, time and additives Wet ashing, loss of boron when using different acids, boron contamination from glassware and other related aspects Extraction of plant samples During drying and grinding neither loss nor contamination of boron was observed. It was found that boron was slightly lost when muffling at temperatures higher than 550°C. The addition of Ca(OH)2 prevented the loss but gave rise to incomplete ashing in many cases. Nitrate salts added in order to enhance oxidation gave rise to boron loss. Wet ashing should be done preferably in a concentrated sulphuric acid or phosphoric acid medium at low temperatures. At higher temperatures the shape of the digestion flask is important ‐ long neck flasks are usually safe enough due to their conde...