1070-4272/04/7702-0215 C 2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 2, 2004, pp. 215!217. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 2, 2004,
Original Russian Text Copyright + 2004 by Slizhov, Gavrilenko.
AND ION-EXCHANGE PROCESSES
Determination of Metal Traces in Polypropylene
by Gas Chromatography
Yu. G. Slizhov and M. A. Gavrilenko
Tomsk State University, Tomsk, Russia
Received May 10, 2001; in final form, December 2003
Abstract-A procedure was developed for determination of metal traces in polypropylene on chromatographic
sorbents and phases of various polarities. The thermal stability of volatile aluminum, chromium, and gallium
acetylacetonates under the conditions of gas chromatography was studied. The influence exerted on the de-
termination process by the column material, temperature, and polarity of phases was examined.
Polyolefins, and polypropylene in particular, are
produced on catalysts containing complexes of Al, Ti,
Cr, and other metals . Evaluation of the quality
of the finished product involves determination of the
residual catalyst, which is commonly done photomet-
rically. The capability of many metals to form ther-
mally stable volatile b-diketonates  offers an oppor-
tunity to use gas chromatography for determining
metals in polyolefins [5, 6]. Therefore, study of chro-
matographic properties of metal b-diketonates and
assessment of the possibility of using them to deter-
mine impurities in polyolefins is topical problem.
In this study, we examined the possibility of deter-
mining metals at their content of 10
by gas chromatography with a simplified sample pre-
The metal acetylacetonates Al(acac)
were prepared as described in . The
sample purity was checked by IR spectroscopy (4003
, Specord M80 spectrophotometer). The
thermal analysis was performed with a Q-1500 deriv-
atograph in the temperature range 203500oC at a heat-
ing rate of 10 deg min
, using Al
The sample weight was 50 mg. Chromatographic ex-
periments were performed with a Chrom 5 chroma-
tograph equipped with a flame ionization detector.
Glass and Teflon columns were packed with Tsvetosil
M-SKT and Tsvetosil SKTFT diatomite supports
modified with chemically grafted silicone rubbers, or
with Chromosorb G AW DMDS impregnated with
SE-30, OV-1, or SKTFV-803 (phenylvinylsilicone
phase) liquid phases.
The metal impurities in polypropylene were deter-
mined as follows. A weighed portion of the polyolefin
powder (4 g) was placed in a 100 cm
round-bottomed flask, 12 cm
of acetylacetone was
added, and the mixture was heated at 60oC for 60 min.
After cooling, the solution was filtered through a
finely porous glass frit and vacuum-evaporated to
dryness. The dry residue was dissolved in 6 cm
. The sample volume was 0.4 ml. The chromato-
graphing conditions were as follows: column, vaporiz-
er, and detector temperatures 140, 190, and 180oC,
respectively; carrier gas flow rate 35 cm
The total analysis time was 1.5 h.
The possibility of direct reaction of b-diketones,
including acetylacetone, with metals embedded in
a polymeric matrix was demonstrated in [8, 9].
The metal transforms into the corresponding acetyl-
acetonate on treatment of the polymer powder with
the hot b-diketone. The IR spectra of the compounds
thus prepared agreed with published data . The
strong bands at 1545 and 1590 cm
of metal acetylacetonates, are indicative of the pres-
ence of a conjugated system of C=O and C=C bonds.
bending vibration band is observed at
. The IR data allow the compounds ob-
tained to be identified as acetylacetonates of the cor-
According to thermal gravimetric analysis, alumi-
num, gallium, and chromium acetylacetonates are
stable up to temperatures exceeding 170oC (Table 1).