What does a headspace sampler do?
A headspace sampler transfers a controlled portion of the gas above a sealed liquid or solid sample into a gas chromatograph. It is used for suitable volatile compounds while limiting non-volatile matrix transfer.
Knowledge
Chromatography Technical Q&A
Concise technical answers designed around real selection questions, method boundaries and verifiable system relationships.
First published: 2026-09-20 · Last updated: 2026-09-20 · Publisher: Shanghai Huishi Instrument Equipment Co., Ltd.
Questions
Headspace vs thermal desorption: what is the difference?
Headspace samples vapour equilibrated above a sealed specimen; thermal desorption usually releases compounds previously collected on a sorbent or emitted from a material. Their sampling and calibration chains are different.
What is pyrolysis GC used for?
Pyrolysis GC is used for controlled thermal decomposition and chromatographic comparison or characterisation of non-volatile materials such as polymers, rubbers, plastics and coatings.
What instrument measures polymer molecular weight distribution?
Analytical GPC/SEC is commonly used to determine relative molecular-weight distribution, using a pump, injector, size-exclusion columns, a suitable detector, calibration and data processing.
GPC analysis vs GPC cleanup: what is the difference?
Analytical GPC/SEC characterises polymer molecular size distribution. GPC cleanup is sample preparation that separates matrix components before a different GC or HPLC determination.
What gases does a gas chromatograph need?
A GC needs a method- and instrument-compatible carrier gas, while particular detectors may also require hydrogen, air or make-up gas. Type, purity, pressure and flow must follow the instrument and method.
Hydrogen generator vs cylinder for GC: how do you choose?
Choose between a generator and a cylinder by reviewing required purity, peak and continuous flow, pressure, installation, ventilation, local safety rules, redundancy and total operating practice.
Why use post-column derivatization in HPLC?
Post-column derivatization is used when a separated analyte must react after the column to form a product that is more selective or responsive for the chosen detector.
GC vs HPLC: which technique fits the sample?
GC generally fits volatile, thermally stable or derivatisable compounds; HPLC generally fits less volatile, thermally sensitive or strongly polar compounds. The official method and detector ultimately control the choice.
FID vs TCD: how do you choose?
FID responds well to many organic compounds, whereas TCD is a broader concentration detector that can cover gases with different sensitivity. Selection depends on analytes, concentration, carrier gas and the method.