Determination of elements in agricultural soils using IR laser ablation inductively coupled plasma atomic emission spectrometry

Direct sampling of soil samples was studied using laser ablation inductivel y coupled plasma atomic emission spectrometry (LA-ICP-AES). Samples were pr essed into pellets together with a binder and an internal standard. The amo unt of ablated material for pellets with various binding materials was eval uated. Silver and aluminium powders were found as adequate binders for the pellet preparation. Optimisation of laser parameters, and sample displaceme nt during interaction have been performed. Moderate laser pulse energy of 1 50 mJ together with a 20-Hz repetition rate was found to be the most suitab le to obtain stable analytical signal. Sample displacement leads to more pr ecise sampling and long time signal plateau that can be measured even with sequential spectrometers. precision was approximately 5% fur most of the el ements studied. Calibration was performed using soil samples spiked with so lutions, internal standards improved correlation coefficients for calibrati on, which were at least 0.98. Germanium powder was the most efficient inter nal standard. Certified reference soils were analysed with an accuracy bett er than 10%, (C) 2000 Elsevier Science B.V. All rights reserved.