Why does the site say “<155 nm” instead of an exact lower bound?

GC-UV detection extends well into the vacuum-UV, but the exact lower wavelength a given system reaches depends on the flow cell design, window material, carrier-gas purity, optical path length, and the absorbing species in the sample. Quoting a single fixed number would imply a guaranteed limit across all configurations and matrices, which isn't physically accurate. “<155 nm” communicates the meaningful capability — operation in the vacuum-UV — without overstating performance you can't reproduce in your own setup.

What actually limits the lower wavelength?

Three things dominate: (1) absorption by the carrier gas itself (N₂ is largely transparent down to ~145 nm; O₂ and H₂O cut in much earlier), (2) the transmission cutoff of the flow-cell windows (MgF₂, LiF, and synthetic silica each have different deep-UV cutoffs), and (3) lamp emission and detector quantum efficiency at very short wavelengths. INSCAN is engineered so all three are pushed as far into the vacuum-UV as the application requires.

Does GC-UV always operate at the lowest possible wavelength?

No — and it shouldn't. The optimal wavelength window is chosen per analyte. Many compound classes have their strongest, most selective absorption bands above 155 nm. Going lower buys you sensitivity for non-UV-active compounds and class-level fingerprints, but it isn't free: shorter wavelengths require stricter purge, cleaner gas, and shorter optical paths.

How should I interpret the spec sheets?

Treat the published range (typ. <155–330 nm) as the envelope INSCAN can operate within. The wavelength range that's relevant to your method is a subset chosen during method development, based on your analytes, matrix, and required limits of detection. Our applications team confirms the working window during a feasibility scan.

Is “<155 nm” a marketing hedge?

It's the opposite — it's the honest framing. A specific sub-155 nm number would only be defensible under one configuration with one sample. The “<155 nm” phrasing matches how peer-reviewed GC-UV literature describes vacuum-UV operation, and it's consistent with how spectroscopy vendors quote ranges (e.g. “below 200 nm” for deep-UV HPLC detectors).

What does “far below 155 nm” actually mean in practice?

“Far below 155 nm” means the optical path is engineered to keep transmitting useful signal deep into the vacuum-UV — typically into the 130–150 nm region, and in some configurations approaching the LiF cutoff near 105 nm. In that regime almost every organic molecule has a strong σ→σ* or n→σ* absorption, so even compounds that look “UV-transparent” in conventional HPLC detectors (alkanes, fixed gases, simple halocarbons) become detectable with class-specific spectra.

What limits performance at the deepest wavelengths?

Four things, in order of impact: (1) residual O₂ and H₂O in the carrier and purge gas — both absorb strongly below ~180 nm; (2) window contamination — even a monolayer of pump oil, plasticiser, or fingerprint residue raises the cutoff dramatically; (3) lamp ageing — D₂ and Xe lamps lose deep-UV output before they lose visible output; (4) sample loading — overloaded peaks saturate the detector and broaden into the baseline.

How should customers prepare samples for deep-UV GC-UV work?

Treat it like trace GC-MS, with two extra rules. First, eliminate water and oxygen from the sample path: dry solvents, low-bleed septa, and a fresh split liner before any deep-UV run. Second, control matrix loading — dilute heavy matrices so total mass on-column stays below ~100 ng per analyte. Use UV-grade carrier gas (≥99.9999% N₂ or He) with an in-line O₂/H₂O trap.

Why is GC-UV better than GC-MS for xylene isomer analysis?

Ortho-, meta- and para-xylene share an identical molecular formula and produce effectively identical mass spectra. Their UV absorption spectra in the 176–330 nm range, by contrast, are sharply different — INSCAN distinguishes the three isomers from a single chromatographic peak even when they co-elute.

Can INSCAN run BTEX analysis to ASTM-equivalent precision?

Yes. INSCAN delivers BTEX speciation at ppm-to-ppb levels with linearity comparable to or better than ASTM D5580 / D6730 reference workflows, and adds an isomer-resolved aromatic profile that FID-only methods cannot provide.

Is INSCAN suitable for online process or near-line refinery analysers?

INSCAN OEM is designed for integration into online and near-line process analysers. It provides UV detection at acquisition rates up to 200 Hz and operates without consumable gases beyond standard GC carrier supplies.

How does GC-UV handle aromatics in polymer-grade olefin streams?

UV detection is selective for aromatic species over saturates by more than three orders of magnitude. This makes ppm- and sub-ppm-level confirmation of benzene and toluene in polymer-grade ethylene and propylene routine, without the matrix-induced ion-suppression issues that affect GC-MS.

Does INSCAN speciate sulfur and nitrogen aromatics for hydrotreater control?

Thiophenes, benzothiophenes, dibenzothiophenes and pyridines all show diagnostic UV absorption features that INSCAN can quantify and distinguish from background hydrocarbons — useful for both regulatory reporting and catalyst-protection monitoring.

All impact areas

Petrochemical

Petrochemical & Refining

Q: Why does the site say “<155 nm” instead of an exact lower bound?

GC-UV detection extends well into the vacuum-UV, but the exact lower wavelength a given system reaches depends on the flow cell design, window material, carrier-gas purity, optical path length, and the absorbing species in the sample. Quoting a single fixed number would imply a guaranteed limit across all configurations and matrices, which isn't physically accurate. “<155 nm” communicates the meaningful capability — operation in the vacuum-UV — without overstating performance you can't reproduce in your own setup.

Q: What actually limits the lower wavelength?

Three things dominate: (1) absorption by the carrier gas itself (N₂ is largely transparent down to ~145 nm; O₂ and H₂O cut in much earlier), (2) the transmission cutoff of the flow-cell windows (MgF₂, LiF, and synthetic silica each have different deep-UV cutoffs), and (3) lamp emission and detector quantum efficiency at very short wavelengths. INSCAN is engineered so all three are pushed as far into the vacuum-UV as the application requires.

Q: Does GC-UV always operate at the lowest possible wavelength?

No — and it shouldn't. The optimal wavelength window is chosen per analyte. Many compound classes have their strongest, most selective absorption bands above 155 nm. Going lower buys you sensitivity for non-UV-active compounds and class-level fingerprints, but it isn't free: shorter wavelengths require stricter purge, cleaner gas, and shorter optical paths.

Q: How should I interpret the spec sheets?

Treat the published range (typ. <155–330 nm) as the envelope INSCAN can operate within. The wavelength range that's relevant to your method is a subset chosen during method development, based on your analytes, matrix, and required limits of detection. Our applications team confirms the working window during a feasibility scan.

Q: Is “<155 nm” a marketing hedge?

It's the opposite — it's the honest framing. A specific sub-155 nm number would only be defensible under one configuration with one sample. The “<155 nm” phrasing matches how peer-reviewed GC-UV literature describes vacuum-UV operation, and it's consistent with how spectroscopy vendors quote ranges (e.g. “below 200 nm” for deep-UV HPLC detectors).

Q: What does “far below 155 nm” actually mean in practice?

“Far below 155 nm” means the optical path is engineered to keep transmitting useful signal deep into the vacuum-UV — typically into the 130–150 nm region, and in some configurations approaching the LiF cutoff near 105 nm. In that regime almost every organic molecule has a strong σ→σ* or n→σ* absorption, so even compounds that look “UV-transparent” in conventional HPLC detectors (alkanes, fixed gases, simple halocarbons) become detectable with class-specific spectra.

Q: What limits performance at the deepest wavelengths?

Four things, in order of impact: (1) residual O₂ and H₂O in the carrier and purge gas — both absorb strongly below ~180 nm; (2) window contamination — even a monolayer of pump oil, plasticiser, or fingerprint residue raises the cutoff dramatically; (3) lamp ageing — D₂ and Xe lamps lose deep-UV output before they lose visible output; (4) sample loading — overloaded peaks saturate the detector and broaden into the baseline.

Q: How should customers prepare samples for deep-UV GC-UV work?

Treat it like trace GC-MS, with two extra rules. First, eliminate water and oxygen from the sample path: dry solvents, low-bleed septa, and a fresh split liner before any deep-UV run. Second, control matrix loading — dilute heavy matrices so total mass on-column stays below ~100 ng per analyte. Use UV-grade carrier gas (≥99.9999% N₂ or He) with an in-line O₂/H₂O trap.

Aromatic isomers, BTEX, and feedstock streams resolved without ambiguity.

The Context

Aromatics define the value and the regulatory profile of refinery streams — yet ortho, meta and para isomers of xylene, ethyltoluene or trimethylbenzene give effectively identical mass spectra. Producers, blenders and certification labs need detection that distinguishes these structures with the speed of online or near-line analysis. GC-UV's vapour-phase electronic spectra are sharp, reproducible and tied directly to molecular structure, making it the orthogonal partner to GC-MS that the industry has been waiting for.

The Challenges

What conventional detection misses.

Co-eluting C8 / C9 aromatics

Xylene isomers and ethylbenzene routinely co-elute on production-grade columns and are indistinguishable by quadrupole MS.

Sulfur and nitrogen species speciation

Thiophenes, benzothiophenes and pyridines must be speciated for both regulatory reporting and catalyst protection.

Trace aromatics in olefin streams

Polymer-grade ethylene and propylene require ppm-level confirmation of benzene and toluene with regulator-grade certainty.

The GC-UV Answer

How INSCAN resolves it.

UV absorption directly distinguishes ortho/meta/para isomers via characteristic π-π* transitions.
Selectivity for aromatics over saturates simplifies chromatography on complex matrices.
Linear, calibration-stable response across a wide dynamic range — suitable for both bulk and trace work.

At a glance

Aromatic selectivity: >10³ vs. saturates
Isomer resolution: ortho / meta / para baseline
Acquisition rate: Up to 200 Hz

The Workflow

What the lab actually does.

STEP 01
Stream sampling
Compatible with standard liquid, gas, and headspace introduction systems.
STEP 02
GC separation
Use existing PONA, DHA, or aromatic-selective columns.
STEP 03
Selective detection
INSCAN reports both retention time and full UV spectrum, distinguishing co-eluting isomers.
STEP 04
Reporting
ASTM / EN method-compliant outputs for blending, certification, and regulatory submission.

Where it's used

Typical applications.

BTEX speciation in fuels and feedstocks
Xylene isomer ratio in reformate streams
Aromatics in polymer-grade olefins
Sulfur-containing aromatics for hydrotreating control
Process optimisation in catalytic reforming

Recommended platforms

The right INSCAN for Petrochemical.

Recommended

INSCAN X

High-throughput configuration for refinery and certification labs.

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Recommended

INSCAN OEM

Detector engine for online and near-line process analysers.

Explore product

Questions answered

GC-UV for Petrochemical — FAQ.

Specifics that matter to lab managers, method developers and process owners evaluating GC-UV against existing GC-MS or GC-FID workflows.

Why is GC-UV better than GC-MS for xylene isomer analysis?: Ortho-, meta- and para-xylene share an identical molecular formula and produce effectively identical mass spectra. Their UV absorption spectra in the 176–330 nm range, by contrast, are sharply different — INSCAN distinguishes the three isomers from a single chromatographic peak even when they co-elute.
Can INSCAN run BTEX analysis to ASTM-equivalent precision?: Yes. INSCAN delivers BTEX speciation at ppm-to-ppb levels with linearity comparable to or better than ASTM D5580 / D6730 reference workflows, and adds an isomer-resolved aromatic profile that FID-only methods cannot provide.
Is INSCAN suitable for online process or near-line refinery analysers?: INSCAN OEM is designed for integration into online and near-line process analysers. It provides UV detection at acquisition rates up to 200 Hz and operates without consumable gases beyond standard GC carrier supplies.
How does GC-UV handle aromatics in polymer-grade olefin streams?: UV detection is selective for aromatic species over saturates by more than three orders of magnitude. This makes ppm- and sub-ppm-level confirmation of benzene and toluene in polymer-grade ethylene and propylene routine, without the matrix-induced ion-suppression issues that affect GC-MS.
Does INSCAN speciate sulfur and nitrogen aromatics for hydrotreater control?: Thiophenes, benzothiophenes, dibenzothiophenes and pyridines all show diagnostic UV absorption features that INSCAN can quantify and distinguish from background hydrocarbons — useful for both regulatory reporting and catalyst-protection monitoring.

Talk to us about Petrochemical.

Application notes, sample testing, and integration discussions for licensing, co-development, and OEM partners.

More areas of impact

Petrochemical & Refining

What conventional detection misses.

Co-eluting C8 / C9 aromatics

Sulfur and nitrogen species speciation

Trace aromatics in olefin streams

How INSCAN resolves it.

What the lab actually does.

Stream sampling

GC separation

Selective detection

Reporting

Typical applications.

The right INSCAN for Petrochemical.

INSCAN X

INSCAN OEM

GC-UV for Petrochemical — FAQ.

Talk to us about Petrochemical.

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