Electrothermal Atomic Absorption Spectrometric Determination of Potassium in Biological Materials with a Molybdenum Tube Atomizer

Abstract Electrothermal atomic absorption spectrometry (ETA-AAS) of potassium in biological materials with a molybdenum tube atomizer has been investigated. The atomization characteristics of potassium on the atomizer are demonstrated. The optimal gas flow rate was 400 ml min −1 Ar and 100 ml min −1 H 2 . The characteristic mass (the mass of element giving 0.0044 abs.) of potassium by the atomizer was 75 fg, which is better than that obtained with a graphite atomizer. The detection limit ( s / n = 3) was 72 fg (corresponding to 7.1 pg ml −1 with 10 μl given). The value was also better than those from flame AA, graphite furnace AA, and flame atomic emission. The relative standard deviation by the use of the molybdenum atomizer was 2.6%. Interferences caused by large amounts of interferents were evaluated. Thiourea as the matrix modifier eliminated the interferences. The determined potassium in biological materials was in good agreement with the certified values. For a graphite furnace AAS, the recommended method will serve as a highly sensitive determination of potassium in biological materials, when a molybdenum or tungsten metal foil lined into the graphite furnace is used in argon + hydrogen purge gas.