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.

Question 1

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

Accepted Answer

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.

Question 2

What actually limits the lower wavelength?

Accepted Answer

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.

Question 3

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

Accepted Answer

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.

Question 4

How should I interpret the spec sheets?

Accepted Answer

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.

Question 5

Is “<155 nm” a marketing hedge?

Accepted Answer

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).

Question 6

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

Accepted Answer

“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.

Question 7

What limits performance at the deepest wavelengths?

Accepted Answer

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.

Question 8

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

Accepted Answer

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.

Specification	INSCAN	INSCAN X	INSCAN LAB	INSCAN OEM
System	GC-UV INSCAN 176 injector system	—	—	—
Measuring principle	Gas chromatography with UV detection (GC-UV)	—	—	—
Detector spectral range	<155 – 330 nm	—	—	—
Application range cited in brochure	<155 – 330 nm	—	—	—
Analysis mode	Full-scan qualitative and quantitative analysis	—	—	—
Sample focus	Liquid samples introduced through integrated GC injector	—	—	—
Runtime	Typically > 5 min	—	—	—
Carrier gas	Nitrogen	—	—	—
Electrical supply	230 V / 50 Hz	—	—	—
Power	≤ 500 W	100–240 V AC, 400 W	100–240 V AC, 200 W	24 V DC, 60 W
Connectivity	USB 1 plus dedicated USB 2 spectrometer port	—	—	—
Architecture	Integrated system with no vacuum pumps or external add-ons	—	—	—
Detector type	—	Deep-UV absorbance, ruggedized	Deep-UV absorbance, modular	Deep-UV absorbance OEM core
UV range	—	<155 – 330 nm	<155 – 330 nm	<155 – 330 nm
Flow cell	—	High-flow heated cell, 280 °C	Interchangeable, 200 °C	Customer-specified, OEM mount
GC compatibility	—	Process & lab GCs, split/splitless	All major lab GCs	—
Data rate	—	up to 100 Hz	up to 50 Hz	up to 200 Hz
Dimensions (W×D×H)	—	650 × 720 × 540 mm	380 × 420 × 240 mm	180 × 220 × 95 mm
Operating environment	—	5–40 °C, IP54 enclosure	15–30 °C lab conditions	—
Software interface	—	Modbus TCP, OPC UA, INSCAN Suite	Python SDK, INSCAN Suite, CSV/JSON export	—
Host compatibility	—	—	—	Any GC chassis with 24 V supply
Signal output	—	—	—	TTL, RS-485, Ethernet, analog 0–10 V
Certification	—	—	—	CE, FCC Class A, RoHS

Criterion	GC-UV	GC-VUV	HPLC	GC-FTIR	LC-MS	LC-MS/MS	GC-MS
Detection principle	Vacuum-UV absorbance (<155–330 nm)	Vacuum-UV absorbance (125–240 nm)	UV/Vis, RI, fluorescence	Mid-IR vibrational absorbance	Soft ionization + m/z	Tandem MS, m/z + fragments	EI ionization + m/z
Wavelength / mass range	<155–330 nm	125–240 nm	190–800 nm	4000–400 cm⁻¹	50–2000 m/z	50–2000 m/z (MS²)	10–1000 m/z
Structural isomer ID
Positional isomer ID (o-, m-, p-)
Molecular fragmentation
Vacuum required
Carrier / mobile phase	He / N₂ / H₂	He (high purity)	Solvents (water, MeCN, MeOH)	He / N₂	Solvents + buffers	Solvents + buffers	He (high purity)
Quantification model	Lambert-Beer (absolute)	Lambert-Beer (absolute)	Response factor	Beer-Lambert / library	MS calibration curve	MRM calibration	MS calibration curve
Sample throughput	5–10 min	10–20 min	15–45 min	10–20 min	10–30 min	10–30 min	15–40 min
Typical detection limit	ppb	ppb	ppm–ppb	ppm	ppb	sub-ppb	ppb
Compound-class fingerprinting
Relative capex	Low–Mid	Mid	Low	Mid	High	Very high	Mid
Relative running cost	Low	Mid	Mid (solvents)	Low	High	Very high	Mid
Best-fit applications	Fuels, petrochem, isomers, process	PIONA, permanent gases	Pharma, food, large molecules	Functional groups, polymers	Pharma, proteomics, metabolomics	Trace quant, clinical, residues	Volatiles, environmental, forensics

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Pick the right GC-UV configuration.

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