LOW-COST, MODULAR ELECTROTHERMAL VAPORIZATION SYSTEM FOR INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

In this investigation, commercially available tungsten filaments were employed to electrothermally vaporize liquid samples prior to their in troduction into an inductively coupled plasma (ICP), These filaments w ere extracted from standard 150 W slide projector bulbs. The temperatu re of the tungsten coil was controlled by supplying a desired current at 120 V ac. A small sample volume, typically 20 mu L, was manually pi petted onto the coil and dried at a 2.3 A current. At the conclusion o f this dry step, a 7.4 A atomization current was applied, and sample a toms were sputtered off the coil and rapidly introduced into the plasm a as a dense plug by a Bow of Ar/H-2 gas. A charge-coupled device (CCD ) array detector allowed for multielement determinations. Simultaneous ly 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 eit her as cumulative poisons or as essential nutrients, Each also possess es one or more strong ICP emission lines in the spectral range of the CCD detector. The utility of this inexpensive electrothermal vaporizat ion (ETV)-ICP method is evaluated for botanical and biological samples through the use of standard reference materials (NIST SRM 1547 ''Peac h Leaves'' and NIST SRM 1566a ''Oyster Tissue'').