Improve atomic absorption detection limits, do solid samples with Perkin-Elmer's HGA-70 Graphite Furnace.

A f l ame less s a m p l i n g dev i ce fo r a tom ic a b s o r p t i o n , P e r k i n - E l m e r ' 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 t imes over the c o n v e n t i o n a l burner. In fact, its sensitivity challenges neutron activation. Below are selected detection limits expressed in ^ g / m l , b a s e d on 1 0 0 - m i c r o l i t e r s a m p l e solutions. Element Graphite Furnace Flame Ag 0.000007 0.002 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 'W i th Perkin-Elmer Model 403.

Dries, ashes and atomizes. The Perkin-Elmer Graphite Furnace

is basically a hollow cyl inder 5 cm long and 1 cm wide, through which the sam­ple beam passes. It is surrounded by a water-cooled metal enclosure. The inner space is continuously purged with an inert gas, usually ni trogen.

To insert sample solut ion, simply p i p e t t h e s a m p l e i n t o 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 microl i ters. Solid or u n d i s s o l v e d s a m p l e s a re i n s e r t e d through the end of the cyl inder with an accessory Sampling Spoon.

A touch of a button puts the Furnace through an automatic three-step pro­gram: 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 cur­rent up to 500 amps produces tem­peratures as high as 2700°C. For all three steps, temperature and t iming are under the operator 's contro l . 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

of the Furnace is directly proport ional 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 trac­ing would have been 100 times smaller.

Low sample capacity important, too. In some appl icat ions, the sample sup­

ply is very l imited. The Perkin-Elmer Graphite Furnace can work with solu­tions as low as 0.1 microl i ter 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 mil l igrams were rol led into small balls, weighed and inserted into the Furnace. Excellent reproducibi l i ty at very low concentrat ions was achieved.

0 30

0.25

0 20 -

< S ο. 5 -

ΟΙΟ

0.05

2.6 mg

l.6mg l.6mq

30 mg

ΙΟ μΙ OF 0.2 Mg/ml (2 ng OF GOLD)

Sample Wt. 1.6 mg 1.6 mg 2.6 mg 3.0 mg The analytical result by another method was 1.1 Mg/gm gold.

For full details on the HGA-70, wr i te: Instrument Division, Perkin-Elmer Cor­poration, 702 Main Avenue, Norwalk, Conn. 06852.

9 0 -

8 0 -

7 0 -

6 0 -

5 0 -

4 0 -

3 0 -

2 0 -

I 0 -

0 -Figure 1.

Tracing for 0001 ' ' g / m l (1 ppb) silver.

40 A · ANALYTICAL CHEMISTRY, VOL. 44, NO. 1, JANUARY 1972

CIRCLE 140 O N READER SERVICE CARD

PERKIN-ELMER

Peak Ht. Concentrat 'n 30 1.1 Mg/gm 33 1.2Mg/gm 48 1.1 Mg/gm 58 1.1 Mg/gm

ol

Figure 2. Gold in polyesters.