Slurry analysis by multichannel arc/spark emission spectrometry using a monosegmented system: Determination of aluminium in sediments

This work proposes a new approach for sediment analysis in which the sample is introduced as a slurry in an arc/spark emission spectrometer using a monosegmented system. The spectrometer has been modified to employ a 1024 photodiode-array detector capable of collecting intensities in a 18.7 nm wide wavelength window. Sediment slurries were prepared with 8.5-50 mg of the samples, grounded to a particle size less than 38 mu m, transferred to a 50 mL volumetric flask in which 1 mL of conc.HNO3 and 300 mu L of 10% m/v La (as La2O3; used as internal standard) were added. The slurry (25 mu L) was introduced into the monosegmented system and transported by an air stream to a graphite rod in the existing arc/spark source. About 40 samples can be analyzed per hour. Results for reference materials show acceptable accuracy and precision for the proposed method. (C) 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:46-52, 2000.121465

Direct analysis of coffee and tea for aluminium determination by electrothermal atomic absorption spectrometry

A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described. Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved at 105 mu m and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases and the determinations were carried out in the linear range between 50 and 250 mu g L-1. The characteristic mass of aluminium and the detection limit were 45 pg and 2 mu g L-1, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n = 15) for repeatability was about 8.2%.13219510