Preparation of Potassium-Bromide Disks for Infrared Microanalysis by Use of a Half-In K. J. Sterling, Basic Research Division, Research Department, ISCOR, P.O. Box 450, Pretoria, South Africa EVERAL
techniques have previously
S been described for the preparation of
halide disks for infrared spectrometry of microgram samples. However, all these methods require the use of special equip ment such as microdies and micropellee holders. In laboratories where relatively few microsamples are handled, commercially available microdisk equip mentis not readily found.
b.
0.
Figure 2
By use of an evacuable die for pressing half-inch halide disks contained in stainless steel rings, a technique has been developed for the incorporation of microgram samples. A drill guide was made to drill a small hole exactly in the center of a previously weighed blank KBr disk (Figure 1). After the drilling, loss in weight is ascertained. An amount of KRr, 10% in excess of that lost during drilling is weighed into a m a l l sample tube. From a suitable anhydrous volatile solvent, 5 to 30 pg. of sample are transferred to the sample tube and are thoroughly mixed using a small spatula. Prior to mixing. the sample from the KBr should have a
0.
Disk with 1.7-mm. hols
b.
Pressed microdisk Microdisk with mask
C.
Z T
(b)
4.0
3.5
Figure 3. 0,
b.
H
Figure 1 A. B. C.
D.
1a04
Twistdrill, 1.7 mm. Driilguide Stainless steel ring Mark with 1.5-mm. hole
ANALYTICAL CHEMISTRY
3.0
2.5
2.0
1.8 1.6
1.4.
2-Hydroxy-4-nitro-benzoldehydept
1 0 pg. in 6 mg. of KBr, 1.5-mm. diomster disk, no ordinate expq rote: 1 0 0
