Instrumentation

Development of a Curie-Point Headspace Sampler forCapmary Gas Chromatography
Naoki Oguri’ and Akira OnishOnishi
Japan Analytical Industry Co. Ltd, Musashi, Mizuho, Nishitama, Tokyo l90-l2, Japan
Toshihiko Hanai
lnt. Inst. TechnoL Anal., Health Res. FondJnst Pasteur de Kyoto 5F, Sakyo-ku, Kyoto 606, Japanvalve (Figure 3A) into the adsorption
The Model JHS-100 injecton system
tube which is cryogrnically cooled with
1 Introduction
fromliquid nitrogen. Here they become adBecause of Its Separating Power. Capillary Japan Analytical Industry Co Ltd (Tokyo,
sorbed on the glass wool, Tenax or othergels Chromatography has been used inKey Words:
material used to pack the tube The 8pport
many dlfferent fields; to a large extent.
Capillary gas chromatography
valve is then switched to the defrost posihowever, the success of the technique isMultipurpose sample injector
tion (Figure 3B) and the adsorption tube
dependent on the method used for sample Curie-point desorption
warmed to 30°C (in order to obtain symintroduction. Examples of on-line samCurie-point pyrolyzer
metrical gas chromatographic peaks after
pling methods include purge and trapdesorption) When the adsorption tube has
sampling for the analysis of volatile comSummary
reached room temperature the 8-port valve
pounds in water [1-3], headspace samA Curie-point headspace sampler (CPHS)
is automatically switched to the analytes
pling for volatile compounds in solids
equipped with a purge and trap sampler
position (Figure 3C) and the analytes[4-6], and pyrolyzers for polymer analysis, has been developed for use with capillary
desorbed by Curie-point heating andetc [7-10]. The disadvnttage of such techgas chromatography. The new systemtransferred on to the capillary column
niques is either the requirement tocan handle a variety of samples, including
The sample vessel can be heated as high as
exchange the sample introduction systemgases, liquids, and solids, and can also be
350 °C for the analysts Of samples such as
whenever the type of sample changes, orused as a pyrolyzer.
heat resistant polymers.
the need to dedicate gas Chromatographs
to specific applications: if a gas Chromato3
Results and Discussion
graphic system is to be used for multipurpose analysis, several sample introduction Japan), shown schematically in Figure 1,
3.1
Analysis of Polycarbonate Resintechniques need to be integrated into one
comprises, essentially. a Sample vessel, a111 mg of polycarbonate resin were meassystemvalve. and an adsorption tube The sample
ured into the sampling vessel used forvessels employed for analysis of different
solids and heated to 250 °C After passage
2
Experimental
types of sample (e g gas, liquid. paste andthrough the valve the extracted analytessolid) are illustrated in Figure 2 Followwere adsorbed on glass wool cooled toing introduction of the sample into a suit- -40 °C with liquid nitrogen following
able vessel the analytes are extracted by Curie-point heating the compounds depurging with helium at an appropriate
sorbed were analyzed by capillary GC-MS,
temperature and pass through an 8-port the chromatograms obtained is illustrated
in Figure 4. The volatile components of
the resin were identified as trichloromethane. Phenol, dichlorobenzene, ε -capro-lactam, lindane, dimethylhexanol, anddioctyl phthalate.

3.4 Anatysis of ABS Resin byCurie-Point Headspace GC andPyrolysis GC

3.2 Analysis of Fermented Soy Bean
When a pyrolysis tube is installed in place
Pasteof the adsorption tube the system may be50 mg of paste were measured into theoperated as a Curie-point pyrolyzer The
sampling vessel used for paste and heated chromatogram obtained from 250 mg ofto 80 °C . The compounds extracted wereABS resin by Curie-point headspace GC isadsorbed on Tenax® at -40 °C and again
shown in Figure 7A
7A; that obtained fromdesorbed by Curie-point heating before
0.3 mg of the same resin by Pyrolysis GC isanalysis by capillary GC-MS The chroshown in Figure 7B . Acrylonitrile,matogram obtained is illustrated intoluene, styrene, and other volatile compounds were identified following CurieFigure 5:
5 the flavor components identified were 2-propanol, cumene, diphenylpoint headspace GC-MS (Figure 7A) andhydroquinone,and N-ethyl-N-phenylben-acrylonitrile,toluene,styrene, methyl‑zenemethanamine.
styrene, and the trimmers acrylonitrileacrylonitrile-styrene (AAS), acrylonitrile3.3 Anatysis of Musty Substances in styrene-acrylonitrile (ASA), and styrenestyrene-styrene (SSS) following pyrolysis
Wa t e r(Figure 7B) Many of the peaks shown in
A glass bottle with helium gas purging
Figure 7A were identified as monomers ofsystem was connected to a sample vessel
the compounds in Figure 7B, and a trim
packed with calcium. chloride as inmer. SSS, was also observed amongst theFigure 2: in this arrangement the vessel is compounds obtained following. CPHS
being used to trap moisture Compounds
purged from the water were adsorbed on
Unknown peaks. Whether polyrmer addicryogenically cooled Tenax®, desorbed byTives or polymer degradation products,
Curie-point heating , and analyzed byfound using the solid sample injection
capillary GC-MS . A typlcal chromatogram system , can be identified by comparison ofis illustrated in Figure 6 . The substances the chromatogram with that obtained from
responsible for the musty odor of the water pyrolysis GC
were identified as 2-methylisoborneol and In conclusion, this multipurpose injection
geosmin, both present at the 1 ppb level.
system. CPHS, can be applied to the anaThe mass spectra of the compounds arelysis of environmental, food, petrochemialso presented in Figure 6
cal, and biological samples