Low-Cost, Modular Electrothermal Vaporization System for Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

In this investigation, commercially available tungsten filaments were employed to electrothermally vaporize liquid samples prior to their introduction into an inductively coupled plasma (ICP). These filaments were extracted from standard 150 W slide projector bulbs. The temperature of the tungsten coil was controlled by supplying a desired current at 120 V ac. A small sample volume, typically 20 μL, was manually pipetted onto the coil and dried at a 2.3 A current. At the conclusion of this dry step, a 7.4 A atomization current was applied, and sample atoms were sputtered off the coil and rapidly introduced into the plasma as a dense plug by a flow of Ar/H2 gas. A charge-coupled device (CCD) array detector allowed for multielement determinations. Simultaneously collected data are presented for Ag, Ba, Be, Cd, Cu, Fe, Mn, Pb, Sr, and Zn. Many of these test elements are of biological importance either as cumulative poisons or as essential nutrients. Each also possesses one or more strong ICP emission lines in the spectral range of the CCD detector. The utility of this inexpensive electrothermal vaporization (ETV)-ICP method is evaluated for botanical and biological samples through the use of standard reference materials (NIST SRM 1547 “Peach Leaves” and NIST SRM 1566a “Oyster Tissue”).