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.

Buyer's guide

Looking for a GC-VUV alternative?

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.

If you're evaluating GC-VUV (gas chromatography with vacuum ultraviolet detection) and balking at the helium dependency, the vacuum-purged optical path or the capex, you're not alone. Most labs end up choosing a vacuum-UV detector for one specific capability — absolute, isomer-level absorbance — and accept the operational tax that comes with it. INSCAN's GC-UV platform gives you the same physics in a simpler envelope. This page is a short, plain-spoken guide to whether GC-UV is the right replacement for your GC-VUV workflow.

Six reasons labs migrate from GC-VUV to INSCAN GC-UV

No vacuum, no purge gas

INSCAN's GC-UV optics operate above 155 nm in ambient atmosphere. There is no vacuum chamber to maintain and no continuous nitrogen purge of the optical path.

Run on nitrogen or hydrogen

Methods are validated on N₂, H₂ and He. Drop your dependence on global helium supply without re-validating against a different detector class.

Lower capex and TCO

A simpler optical assembly and standard deuterium / tungsten sources keep both acquisition and service costs well below typical vacuum-UV instruments.

Same Beer–Lambert quantitation

INSCAN preserves the absolute, response-factor-free quantitation that GC-VUV users already trust — only across the 155–330 nm band where most aromatic and heteroaromatic fingerprints live.

Isomer-level identification

Positional and structural isomers (o-/m-/p-xylene, cis/trans alkenes, phenol substitution patterns) resolve cleanly on full UV spectra, not retention time alone.

Multi-vendor service ecosystem

INSCAN ships from Europe with EU-based support, certified ISO 9001:2015 and ISO/IEC 27001:2022, and a partner network that does not rely on a single North-American supplier.

When GC-UV is not the right swap

We try to be honest. If your method is locked to ASTM D8071 PIONA classification, or if you depend on the 125–155 nm window for permanent-gas work, conventional GC-VUV remains the technically correct tool. INSCAN starts at ~155 nm, which is enough for the vast majority of pharmaceutical, petrochemical and environmental analytes — but not all. Read the full GC-VUV vs GC-UV comparison before you decide.

Next step: a 5-minute fit assessment

Our client portal walks you through a short questionnaire — analyte class, matrix, throughput, regulatory framework — and returns a verdict on whether INSCAN GC-UV is a credible replacement for your current GC-VUV method, with a recommended INSCAN configuration if the answer is yes.

Start the fit assessment See INSCAN specs