2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
A c c e l e r a t e d A g e i n g – D e t e c t i o n o f
V o l a t i l e C o m p o u n d s
Flat pieces of PUFs were placed into accelerated ageing
device (Fig. 2.) composed of quartz tube open on one end
(length 24.5 cm, I.D. 3.5 cm) with input tubing and Teflon
cover. The device was placed under UV discharge tube.
Two SPME devices were inserted into both input and output
tubing (the first with polydimethylsiloxane fibre, the second
with polyacrylate fibre) and the ends of the device together
with SPME holders were covered by aluminium foil to protect
them against the UV light. The irradiation tooks place
for 6 hours. After this period, SPME devices were directly
analyzed by GC/MS.
Fig. 2. Accelerated ageing device
H P L C / M S
For HPLC/MS the Esquire-LC instrument (Bruker Daltonics,
Bremem, Germany) was used. This system consists
of the Agilent HPLC 1100 Series with binary gradient pump,
electrospray ion source and spherical ion trap analyzer. A Supelcosil
LC-18DB column (2.1 × 250 mm, 5 µm particles)
was used (Supelco, USA). Gradient elution from 30 to 100 %
acetonitrile in water in 30 min was used at constant flow rate
of 0.25 ml min –1 . For the detection both UV-VIS detector of
DAD type, and mass spectrometry were used. Drying temperature
in electrospray was 350 °C, nebuilizing gas (n 2 ) pressure
was 50 psi, and drying gas (n 2 ) flow was 14 dm 3 min –1 .
Both positive and negative ions were registered (in separate
runs).
G C / M S
System Agilent 6890n GC/5973 MSD (Agilent Technologies,
Waldbronn, Germany) was employed. The column
was HP-5MS 5 m × 0.25 mm × 0.25 µm, helium at a flow of
1 ml min –1 was used as carrier gas in constant flow mode.
Temperature program was as follows: 50 °C for 1 min, then
to 280 °C at 5 °C min –1 , final isotherm 5 min. 1 µl of sample
was injected in splitless mode at a temperature of 280 °C with
Fig. 3. Structure of PuF hydrolytic degradation product
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splitless time of 1 min. Interface temperature was 260 °C,
temperature of ion source and quadrupole 230 and 150 °C,
respectively. Electron ionization at 70 eV electron energy
was used, spectra were registered in scan mode within the
range of 50–450 amu. nIST 05 spectral library was used for
the identification of separated compounds.
Fig. 4. PuF non-volatile degradation products. Compound
identification: 1: bis(2-ethylhexyl) ester of hexanedioic acid;
2: di-tolyl-isocyanate
Results
Typical LC chromatogams of PUF extract show only
two peaks at the beginning. Using the LC/MS/MS experiments
and MS n with direct insfusion of the sample, the probable
structure of main degradation product was proposed (see
Fig. 3.).
This structure is evidently a fragment of polyurethane
polymer chain.
Fig. 4. shows the chromatogram of hexane extract of
polyurethane after UV irradiation. Using the database search
several peaks were successfully identified, but in many cases
the identification was unsuccesfull, in spite of the fact that the
experimental spectrum was of good quality. The most probable
explanation is that the nIST05 database doesn’t contain
Fig. 5. Volati1e degradation products (PDMS fibre). Compound
identification: 1: 2-methyl-1,3-dioxane; 2: 2,6-diisocyanatotoluene;
3: 6,10-dimethyl-5,9-undecadiene-2-one; 4: 2,5-diterc-butyl-1,4-benzochinone;
5: pentadecane; 6: hexadecane; 7:
2,6-bis(1,1-dimethyethyl)-4-(1-oxopropyl)phenol; 8: dodecanoic
acid methylester; 9: 4-decyl-morpholine; 10: heptadecane; 11:
2,6,10,14-tetramethyl-pentadecane; 12: ?? (isoprenoid alkane);
13: tetradecanoic acid isopropylester; 14: 4-undecyl-morpholine;
15: N,N-dimethyl-1-hexadecanamine; 16: 4-tetradecylmorpholine;
17: squalene; 18: 4-hexadecyl-morpholine