A bomb for the hydrofluoric decomposition of inorganic materials

35s

SHORT

COMMUNICATIONS

hygienic standard for lead in the outdoor atmosphere, i.e. the Soviet Union standard of 0.7 /~gof lead per m3 of air in an average 24-h sample, is taken as a basis for calculation, a standard smoke sample of about z m3 of air should contain enough lead for analysis even if the maximum permissible concentration has not been exceeded. Whatman No. I and 41, and Munktell’s No. oo and ooR filter papers were examined for their suitability in the ring-oven lead analysis. The Munktell’s papers proved more suitable, and the filter paper No. oo showed a better collection efficiency for air-borne particulates.

(Received .4~lCfd.

Scptcmber 3rd,

Cltinl.. A Clfi. I ‘19 (1970)

A bomb

IS)@) 356-358

for the hydrofluoric

decomposition

of inorganic

materials

. During the past ten years the use of hydrofluoric acid as a decomposing agent for inorganic materials has increased considerably, the main reasons for this being that (a) decompositions can be made in vessels of inexpensive plastic materials, (b) silicon can bc determined in samples attacked by hydrofluoric acid, and (c) hydrofluoric acid is now produced in a purer state than before. This renewed interest in the hydrofluoric acid decomposition technique has initiated the construction of various types of polytetrafluoroethylene (Teflon)- or platinum-lined bomb+-0. The present note describes a bomb which can be heated more rapidly than the bombs used previously in this laboratory, has an improved temperature regulation, and has a volume of about IZO ml, which permits dilutions to LOOml in the bomb. The construction of the bomb is shown in Fig. I*. The body and the screw cap were made from a seawater-resistant aluminium alloy (1.0% Si, 0.9% Mg) to avoid the tendency of technically pure aluminium to smear. The inner vessel and lid were made from a 2” diameter rod of dense Teflon (Habia, Sweden). The body was heated with r..7 m of Thermocoax heating element (Philips I-NC-I-IO). The temperature was adjusted by means of an iron-constantan thermocouple and a Philips Plastomatic temperature regulator (450”). A circuit diagram is shown in Fig. 2. During decompositions the bomb was placed on a magnetic stirrer ; the magnet must be covered with Teflon. * Dotrriled

specifications

Aaal. Claim. Ada,

of the bomb

49 (1970) 358-359

arc obtainable

from the authors.

SHORT COMMUNICATIONS

359

Fig. c. Section through pblytctrafluoroctllylcne-Iillcd composition of inorganic rnatcrials. Fig. 2. Circuit diagram

;dutninium

bomb

for hyclrofluoric xicl

tlo-

for hcrrtixig ;md tcmpor~rturo control.

The bomb has been used for the decomposition of silicate minerals and rocks, slags, ores, etc., at temperatures up to 200 O.The heating times required to reach the temperatures Izoo, 150~ and zoo0 were IO, 15 and 20 xnin, respectively. The regulator maintained the temperature within & 0.5”. The authors gratefully GRIMNES

and

Mr.

T.

acknowledge

the technical

assistance given by Mr. S.

NORDISY.

Imtittr te A , U1-tiversity of Oslo, Oslo 3 (Norway) ChmicaZ

I XC. LouN,mhh,%. Artnf.Chc?u., 1.1~3(x955) .kzz. z J. I?. RILEY AND I-1.P. Wxmmnls, Mifrvochi~rt. Ada, ‘1 (1959) 516. 3 J. ITO, Bdl.Chcin. Sm. Jnfmz, 35 (1962) 225. 4 W. WAEILER, Ncttes Jrthvb. Mimrnl . ) /I Okamll., IO I (I cjG.I) I 09. 5 ~.J.LANCMYHR AND S. S~~~~,A.ltal.Clti??t.fIcfa,32 (1965) I. G I. MAY AND J. J. ROWE, Awal.Cl~im. Ada. 33 (19G5) G.#. 7 r;. J. LANGhlYI-IR AND 1’. It. C;RAIT, ivor’&‘. Gad. UndeiwAclsc, 230 (1965). 8 E. KISS, AItaZ. C/tint. Ada. 39 (1967) 223. g

B. BERNAS,

(Received

Aml.

Clwwt.,

October 6th,

40 (xgG8)

rGS2.

1c$3g)

.4wl.

C!!im.

AC/U, ‘{CJ(1970) 358-359