Titanium Determination for Correction of Plant Sample Contamination by Soil1

Abstract

AbstractAn accurate method for determining Ti in plant material and soil was developed. Titanium concentrations in plant and soil were used to correct analytical data of plant materials for contamination by soil. Different digestion schemes were used in the analysis of National Bureau of Standards (NBS) reference materials for Ti. A satisfactory result was obtained when the sample was digested in a Teflon beaker containing HNO3 and HClO4, taken to dryness, baked at 185°C, and then dissolved overnight at room temperature in HF. The solution was made to volume with 3M HCl, in polyethylene, after addition of H3BO3 to complex excess F . Titanium was determined by inductively coupled argon plasma (ICP) spectrometry. Certified Ti values for NBS mineral samples 120b and 692 are 899 and 270 mg kg 1, respectively. This method gave values of 898 ± 14 and 264 ± 6 mg kg 1, respectively. Correction of elemental analysis for soil contamination of plant, rumen fistula, and feces samples using this method agreed well with corrections using Fe or Al as a reference element as well as with determination for Ti by x‐ray fluorescence. Using residual ash content (Si) as a reference element appeared to be less reliable. The assumptions needed to make this correction using Ti are less prone to error than the assumptions needed when Fe, Al, or residual ash are used. It was imperative to use HF in the digestion procedure for quantitative determination of Ti in some samples.