V. Karanassios et al., ELECTRICALLY HEATED WIRE-LOOP, IN-TORCH VAPORIZATION SAMPLE INTRODUCTION SYSTEM FOR INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRYWITH PHOTODIODE-ARRAY DETECTION, Spectrochimica acta, Part B: Atomic spectroscopy, 49(9), 1994, pp. 847-865
A new sample introduction system that can be used for the analysis of
microliter volumes of liquids by inductively coupled plasma atomic emi
ssion spectrometry (ICP-AES) is described. The system consists of an e
lectrically heated W wire-loop which is attached to a thermocouple cer
amic insulator. Ceramic and wire-loop are inserted manually into the c
entral tube of a modified ICP torch, with the top of the wire-loop pos
itioned about 10 cm below the plasma. An inexpensive variac, which plu
gs into a wall socket, is used as a power supply. This in-torch vapori
zation (ITV) sample introduction system was characterized using an ICP
optical emission spectrometer with a photodiode array detector. In th
is pilot study aimed at testing the validity of the approach, spectral
interference effects arising from W emission lines are documented for
Be, Cu, Mn, Sc, Sr, V, Y and Zn and preliminary analytical performanc
e characteristics using an unoptimized wire-loop/torch design are pres
ented. Calibration curves were linear for over three orders of magnitu
de for Sr, Y and Be; the non-linear calibration curves obtained for Cu
were attributed to contamination from the power transfer cables, for
Mg to contamination from the ceramic and for Ca to airborne particles
adhering to the wire-loop. As well, Au-coated W wire-loops proved to b
p sensitive to Hg-0-vapor in air. Precision varied between 1.9 and 4.5
% (10 mu l injection of single element standards) and, estimated absol
ute detection limits were (in pg) Zn (710), V (20), Mn (10), Y (10), S
c (9), Be (1) and Sr (0.4).