Liquid Nitrogen for Forensic Science Labs Using IR Spectroscopy

Infrared Spectroscopy is a key forensic tool for identifying complex compounds, primarily using Fourier Transform Infrared (FTIR) and Gas Chromatography–Infrared (GC-IR) technologies. Both require a steady supply of liquid nitrogen (LN₂) for detector cooling. This guide explains how LN₂ generators offer a reliable solution to bulk deliveries for LN₂ for forensic IR workflows.

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Why LN₂ Supply Matters in Infrared Detection

Infrared spectroscopy is a cornerstone of forensic science, enabling laboratories to identify unknown substances, verify material composition, and differentiate between closely related compounds. Both Fourier Transform Infrared (FTIR) and Gas Chromatography-Infrared (GC-IR) systems rely on infrared detection, though their liquid nitrogen (LN₂) requirements differ depending on detector design and analytical application.

Detector Cooling: High-sensitivity infrared detectors, such as Mercury Cadmium Telluride (MCT) detectors, require LN₂ cooling to reduce thermal noise and operate at ultra-low temperatures. This increases detector sensitivity, allowing clear resolution of weak infrared absorption bands critical for trace evidence and forensic compound identification. In GC–IR systems, LN₂ is always required for cooling the MCT detector, while optional cryogenic trapping of GC effluent (matrix isolation interfaces) may also use LN₂ to improve spectral resolution for very small peaks.
Stability and Reproducibility: Consistent low temperatures provided by LN₂ ensure IR signals remain stable over long analytical runs, which is vital for forensic casework where results must be accurate, reproducible, and legally defensible.
Extended Detector Life: LN₂ cooling prevents detector overheating, extending the operational lifespan of sensitive IR components.

Attributes	FTIR (Fourier Transform Infrared)	GC-IR /GC-FTIR (Gas Chromatography–Infrared)
How it works	Direct IR analysis of a bulk sample (solid, liquid, or gas) without separation.	Mixture is separated by GC, then each component analyzed by IR.
Forensic uses	Drugs (powders, tablets), fibers, paint chips, plastics, explosives residues (bulk). Fast and non-destructive but cannot resolve mixtures or trace-level compounds easily.	Isomer differentiation (e.g., synthetic drugs), accelerant detection in arson cases, explosives mixtures, toxicology samples. Requires volatile, thermally stable samples; more complex.
Use of LN2	Used when FTIR employs an MCT detector to achieve higher sensitivity. DTGS-based FTIR systems run at room temperature and do not require LN₂.	Required for cooling the MCT detector to reduce thermal noise and improve signal-to-noise ratio. Optional LN₂ is used for cryogenic GC effluent trapping (matrix isolation) in specialized GC–IR systems.

Don’t put your lab’s credibility at risk

If LN₂ supply is interrupted, detector cooling stops, leading to rapid warming of the IR detector. This causes a sharp increase in thermal noise, loss of spectral resolution, and possible instrument shutdown.

Interrupted runs can result in unusable data, forcing analysts to repeat experiments and potentially delaying case reports, investigations and court proceedings. Over time, repeated thermal cycling caused by supply interruptions can also shorten detector lifespan and increase maintenance costs.

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Challenges of Traditional LN₂ Supply

Supply Chain Limitations

Reliance on bulk deliveries exposes laboratories to supply disruptions caused by transportation delays, adverse weather, or geopolitical events.
Missed or delayed deliveries can halt forensic workflows, delaying casework and compromising evidence analysis.

Transportation Losses

LN₂ is transported over long distances in cryogenic tanks, where boil-off losses of 30–40% are common during transfer and decanting.
By the time the LN₂ reaches the laboratory, a significant portion has already been lost, raising costs for the customer and reducing efficiency.

Safety Risks

Refilling detector dewars or storage tanks careful handling, maintenance, and troubleshooting.

LN₂ evaporation in enclosed spaces can displace oxygen, creating an asphyxiation hazard.
Handling high-pressure cylinders and cryogenic storage vessels increases operational risks.

Benefits of on-site generation

Continuous, On-Demand Supply

Eliminates dependency on deliveries, ensuring uninterrupted detector cooling.

Operational Simplicity

Plug-and-play systems require minimal setup and only an electrical connection, with intuitive touchscreen control.

Integrated Safety Systems

Built-in protections, safe dispensing, emergency stop functions, and automated standby mode reduce handling risks.

High-purity LN2

Real-time oxygen monitoring and sterile filtration ensure consistent detector performance, avoiding contamination or signal degradation.

Efficiency and Cost Control

Proprietary no-loss pressure system eliminates boil-off losses common in traditional storage, reducing operational costs.

Local Service and Support Network

Noblegen provides factory-trained service engineers who provide fast, reliable technical support to ensure uninterrupted forensic laboratory operations.

· Noblegen is supported by the wider PEAK International Group’s service footprint, with operations in 25+ countries and service centers in 20+ countries.

Our dedicated local teams address regional logistical challenges, offering proactive maintenance plans to keep your systems performing at their best.
Exclusive use of manufacturer-approved parts for consistent, long-term reliability.

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Future-Proof Your Forensic Operations

Forensic laboratories using IR spectroscopy require dependable liquid nitrogen availability to ensure accuracy, continuity, and safety in their analyses. Traditional bulk LN₂ supply chains expose labs to risks of supply disruption, evaporation losses, and safety hazards.

By adopting Noblegen’s on-site LN₂ generation systems, your forensic laboratory can benefit from: