Solid Sampling Techniques for Gas Chromatography

For reasons of health, safety and environmental concern, it is often important to know the nature and amount of volatile components which can evolve during processing, storage and use. For outgassing 

TD-EGA techniques have been reviewed [445], as well as direct solid sampling methods for GC analysis of polymer/additive formulations [955]. 

Principles and Characteristics Solution headspace gas chromatographic sampling has a counterpart in a solvent-free, direct method for the rapid determination of volatile components in solid samples. Volatile and semi-volatile components can be desorbed directly from sample matrices or from sorbent or cryogenic traps without any significant sample preparation. 

In static headspace sampling (SHS), which relies totally on volatilisation to separate analytes from a sample matrix, important factors are related to diffusion and surface area. Precise thermal conditions are needed to determine occluded solvents, residual monomers, and additives in polymers and their composites. In particular, for accurate quantitative analysis in a static headspace experiment, the tem-perature/pressure conditions of the sample vessel are critical. In SHS-GC an aliquot of the headspace vapour in thermodynamic equilibrium with a solid sample (of known weight) is transferred to a GC or GC-MS for separation and identification. HS-GC is characterised by a relatively long thermostating time (up to 25 min) and short analysis time (2 min). With 

The characteristics of solid headspace sampling with an internal standard for the determination of residual volatiles in polymers are given in Table 2.45. Generation of a headspace sample is an equilibrium process that limits the amount of a specific component available for analysis within the practical restraints of time and temperature. Static headspace sampling in atmospheric conditions is limited to about 210°C (oxidation and thermal decomposition of polymers) an alternative is thermo desorption in inert conditions. Sensitivity is enhanced by 100 times using LVI with on-column cry-ofocusing. Solid headspace provides about 10-fold more sensitivity than solution headspace. HS-GC does not suffer from interference fl om the solvent peak or from impurities. Typical detectors used in SHS-GC are FID, BCD and MS. Determination of 

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