Improve atomic absorption detection limits, do solid samples with Perkin-Elmer's HGA-70 Graphite Furnace.
A flameless sampling device for atomic absorption, Perkin-Elmer's HGA-70 Graphite Furnace not only improves the detection limits of metallic elements in solution but analyzes many types of solid samples with little or no pre-treatment. The Graphite Furnace improves detection limits as much as 1000 times over the conventional burner. In fact, its sensitivity challenges neutron activation. Below are selected detection limits expressed in M g / m l , based on 1 0 0 - m i c r o l i t e r sample solutions. Element Graphite Furnace Flame 0.000007 0.002 Ag AI 0.0007 0.03 Bi 0.0004 0.04 Cd 0.000003 0.001 Co 0.0002 0.01 Cr 0.0001 0.003 Cu 0.00002 0.002 Fe 0.0001 0.01 Ir 0.004 2.0 Mn 0.00002 0.002 Ni 0.0003 0.01 Pb 0.0002 0.02 Tl 0.0001 0.03 Zn 0.000004 0.002
of the Furnace is directly proportional to the detection limit. Figure 1 shows an excellent tracing for 100 μ\ of 1-ppb solution of silver. If the furnace had been able to accept only 1 μ\, the trac ing would have been 100 times smaller. Low sample capacity important, too. In some applications, the sample sup ply is very limited. The Perkin-Elmer Graphite Furnace can work with solu tions as low as 0.1 microliter and solids smaller than 0.5 mg. Can do solid samples. Figure 2 shows four tracings for the determination of gold in undissolved polyester fibers, plus one tracing for 2 ng of gold in aqueous solution. A few milligrams were rolled into small balls, weighed and inserted into the Furnace. Excellent reproducibility at very low concentrations was achieved.
"With Perkin-Elmer Model 403.
Dries, ashes and atomizes. The Perkin-Elmer Graphite Furnace is basically a hollow cylinder 5 cm long and 1 cm wide, through which the sam ple beam passes. It is surrounded by a water-cooled metal enclosure. The inner space is continuously purged with an inert gas, usually nitrogen. To insert sample solution, simply pipet t h e sample into t h e c y l i n d e r through small hole on top. Sample can be as small as one-tenth microliter, or as large as 100 microliters. Solid or u n d i s s o l v e d samples are inserted through the end of the cylinder with an accessory Sampling Spoon. A touch of a button puts the Furnace through an automatic three-step pro gram: a low current through the cyl inder walls dries the sample; it is then ashed by heat from a slightly higher current;sample is atomized when a cur rent up to 500 amps produces tem peratures as high as 2700°C. For all three steps, temperature and timing are under the operator's control. High sample capacity important. The Graphite Furnace dries solution samples, so that the amount measured is actually the weight of the element of interest. Therefore the sample capacity
Sample Wt. 1.6 mg 1.6 mg 2.6 mg 3.0 mg
Peak Ht. 30 33 48 58
Concentrat'n 1.1 Mg/gm 1.2Mg/gm Ll^g/gm 1.1 ^g/gm
The analytical result by another method was 1.1 μg| gm gold.
For full details on the HGA-70, write: Instrument Division, Perkin-Elmer Cor poration, 702 Main Avenue, Norwalk, Conn. 06852.
PERKIN-ELMER CIRCLE 146 ON READER SERVICE CARD A N A L Y T I C A L CHEMISTRY, VOL. 4 3 , N O . 1 3 , NOVEMBER 1 9 7 1
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