TRACE METALS IN AIR A new technique Traditionally, the only method available for measuring the trace metal concentration in air has been to draw air through a filter for a long time (say, 8 or 24 hours) and then to identify the particles trapped on the filter by analysis. This procedure gives an average metal concentration but cannot give a measure of variations during the sampling period. To measure the variations, we need to analyze small samples of air, drawn through a filter for a very short time. A new technique has now been developed by Varian Techtron for the specific purpose of collecting and measuring these small samples. The Varian Techtron Air Microsampler is a new, highly sensitive air particulate sampling method which supplements the existing large-volume methods. For the first time, simple and effective tracking of the variations in trace metallic elements in air is possible. In practice, a disk of filter material is placed in a small graphite cup with a perforated base, and air is drawn through the filter with a simple pump. Collection time is about two minutes. The cup with its sample is then transferred to the Varian Techtron Carbon Rod Atomizer for analysis.
varian
In the Carbon Rod Atomizer, the cup is heated electrically through three programmed stages: drying, ashing and then atomization. In the atomization stage the pollutant concentration is measured by atomic absorption. The Air Microsampler makes the most of the excellent analytical sensitivity of the Carbon Rod Atomizer by allowing very low concentrations of metals in air to be quantified. The sensitivity for lead analysis in a 200 ml air sample is 0.1 ^g/m 3 , and for cadmium the sensitivity is 0.008/xg/m3.* In principle, the Air Microsampler could be applied to any metal of interest, and in any atmosphere. In each situation the new method will give a measurement of the airborne metal concentration at a point in time, and by consecutive sampling the variations can be followed over an extended period. Further details are available from Varian offices.
'Matousek J. P., Brodie K. G., Direct Determination of Lead Airborne Particulates by Non-Flame Atomic Absorption, Anal. Chem., 45, (9), 1606, 1973. Brodie K. G., Matousek J. P., Determination of Cadmium in Air by Non-Flame Atomic Absorption Spectrometry, Anal. Chim. Acta., 69, (1), 200, 1974.
Varian Techtron Palo Alto, Cal., U.S.A. Georgetown, Ont., Canada Zug, Switzerland Springvale, V i c , Australia
CIRCLE 239 ON READER SERVICE CARD 594 A · ANALYTICAL CHEMISTRY, VOL. 46, NO. 7, J U N E 1974
