Nitrogen Generators for Analytical Chemistry

Nitrogen generators are sophisticated devices that produce nitrogen gas on-site by separating it from compressed air. These systems offer an on-demand supply of nitrogen, eliminating the need for traditional gas cylinders or liquid nitrogen tanks. The technology behind nitrogen generators has evolved significantly over the past few decades, making them more efficient, reliable, and cost-effective than ever before.

There are two main types of nitrogen generators used in laboratory and industrial settings:

• Membrane Nitrogen Generators use hollow fiber membranes to separate nitrogen from other gases in compressed air. These membranes are typically made from polymeric materials with specific permeability properties. As compressed air passes through bundles of these semipermeable membrane fibers, oxygen, water vapor, and other gases permeate through the membrane walls and are vented off. The larger nitrogen molecules pass through the membrane fibers and are collected as the product gas.

Membrane generators are known for their simplicity and low maintenance requirements. They operate continuously and have no moving parts in the separation process, which contributes to their reliability. However, they typically produce nitrogen with purities ranging from 95% to 99.5%, which may not be sufficient for all analytical applications.

• Pressure Swing Adsorption (PSA) Nitrogen Generators use carbon molecular sieve (CMS) beds to adsorb oxygen and other gases from compressed air, allowing nitrogen to pass through. The system uses two alternating sieve beds - as one bed adsorbs oxygen, the other releases the adsorbed gases and regenerates. This allows for continuous nitrogen production.

PSA systems can typically achieve higher purities (up to 99.9995%) compared to membrane systems, making them ideal for applications requiring ultra-high purity nitrogen. The trade-off is that PSA systems are generally more complex, with more moving parts and higher maintenance requirements than membrane systems.

→ Learn more: Which Nitrogen Generator Technology is Right For Me?

1. Air Compressor: Supplies the initial compressed air. The quality and consistency of the compressed air supply are crucial for the efficient operation of the nitrogen generator.

2. Filtration System: Removes impurities and moisture from the compressed air. This typically includes:

a. Coalescing filters to remove oil and water droplets

b. Activated carbon filters to remove oil vapors and odors

c. Particulate filters to remove solid particles

3. Separation Unit: The core component where nitrogen is separated (either membrane or PSA). This is where the actual gas separation takes place.

4. Storage Tank: Holds the produced nitrogen for on-demand use. The size of the tank depends on the flow rate requirements and usage patterns of the laboratory.

5. Control System: Monitors and controls the entire process, ensuring consistent purity and pressure of the produced nitrogen.

6. Oxygen Analyzer: Continuously monitors the purity of the produced nitrogen, ensuring it meets the required specifications.

The choice between membrane and PSA technology depends on several factors, including:

- Required nitrogen purity
- Flow rate needs
- Available space
- Energy costs
- Maintenance capabilities
- Initial budget constraints

For example, a laboratory primarily using nitrogen for LC-MS might opt for a PSA system to achieve the high purities required for this application. On the other hand, a facility using nitrogen mainly for sample preparation or as a blanket gas might find a membrane system more than adequate for their needs.

On-site nitrogen generation offers several key advantages over traditional gas cylinder or liquid nitrogen delivery, making it an increasingly popular choice for analytical laboratories:

Cost Savings

Generating nitrogen on-site eliminates ongoing costs associated with gas cylinder rental, delivery fees, and administrative overhead. While there is an initial investment in the generator system, most facilities see a return on investment within 12-24 months. Long-term cost savings of 40-80% compared to gas delivery are common.

For example, a medium-sized analytical laboratory consuming 200,000 cubic feet of nitrogen per year might spend around $50,000 annually on delivered nitrogen. By switching to on-site generation, they could reduce this cost to approximately $10,000-$15,000 per year in electricity and maintenance costs, resulting in significant savings.

→ Is it cheaper to generate my own nitrogen gas?

Improved Safety

On-site generation removes the need to handle and transport heavy, high-pressure gas cylinders or cryogenic liquid nitrogen. This significantly reduces workplace injury risks associated with manual handling and potential gas leaks. The lower pressure nitrogen produced by generators (typically 80-100 psi) is inherently safer than high-pressure cylinders (2000-2500 psi).

According to the Compressed Gas Association, there are approximately 11 serious incidents per million cylinders handled. By eliminating cylinder handling, laboratories can significantly reduce their risk of accidents and improve their safety record.

Reliability and Convenience

Nitrogen generators provide a continuous, on-demand supply of nitrogen gas. This eliminates concerns about running out of gas during critical processes or experiments. There's no need to monitor gas levels, schedule deliveries, or change out cylinders, freeing up staff time for more valuable tasks.

Many modern nitrogen generators also come with remote monitoring capabilities, allowing for predictive maintenance and ensuring uninterrupted supply. Some systems can even automatically alert service technicians if performance metrics deviate from expected values.

Consistent Purity and Flow

Generators produce nitrogen at a consistent purity level and flow rate, unlike cylinders which can have purity fluctuations as they deplete. The purity and flow can be adjusted as needed for different applications, providing flexibility that's not possible with delivered gas.

For instance, a single generator system could provide 99.999% pure nitrogen for LC-MS applications and simultaneously supply 99.5% nitrogen for less demanding uses, optimizing both performance and operational costs.

Environmental Benefits

On-site generation eliminates the carbon emissions associated with frequent gas deliveries. A typical nitrogen delivery truck emits about 2.5 kg of CO2 per mile traveled. For a laboratory receiving weekly deliveries from a supplier 50 miles away, switching to on-site generation could reduce their carbon footprint by over 13,000 kg of CO2 per year.

Additionally, on-site generation reduces energy consumption compared to cryogenic nitrogen production. The production of liquid nitrogen is an energy-intensive process, consuming approximately 0.8 kWh per cubic meter of nitrogen. In contrast, PSA and membrane generators typically use between 0.2-0.4 kWh per cubic meter, representing a significant reduction in energy use.

Space Optimization

While nitrogen generators do require some floor space, they often take up less room than the equivalent number of high-pressure cylinders or liquid nitrogen tanks needed to meet the same demand. This can be particularly beneficial in laboratories where space is at a premium.

Quality Control

With on-site generation, laboratories have complete control over their nitrogen supply. They can monitor and adjust purity levels in real-time, ensuring that the gas always meets their specific requirements. This level of control is particularly crucial in regulated industries such as pharmaceuticals, where gas quality documentation is often required.

Nitrogen generators have become indispensable in many analytical chemistry applications, revolutionizing laboratory operations across various sectors. Here's an in-depth look at how nitrogen generators are used in different analytical techniques:

Liquid Chromatography-Mass Spectrometry (LC-MS)

High-purity nitrogen is critical in LC-MS systems, where it serves multiple functions:

- Curtain Gas: Forms a barrier between the sample and the mass spectrometer, preventing contamination.
- Collision Gas: Used in tandem MS experiments for controlled fragmentation of ions.
- Nebulizing Gas: Assists in the formation of a fine spray of sample droplets in electrospray ionization (ESI) sources.

On-site generators ensure a consistent supply for these high-consumption instruments. For example, a typical LC-MS system might require 20-30 liters per minute of high-purity nitrogen (99.999% or higher). A nitrogen generator can provide this continuous flow without the risk of running out during long analytical runs or automated sequences.

Gas Chromatography (GC)

Nitrogen serves as both a carrier gas and makeup gas in many GC applications. Generators provide the consistent purity and pressure required for accurate results. Benefits in GC applications include:

- Stable Retention Times: Consistent gas purity and pressure lead to more reproducible retention times.
- Improved Sensitivity: High-purity nitrogen can enhance detector sensitivity, especially for electron capture detectors (ECD).
- Cost-Effective for High-Flow Methods: For methods requiring high flow rates, on-site generation is particularly economical.

A medium-sized laboratory running multiple GC instruments might consume 50-100 liters per minute of nitrogen. An appropriately sized generator can easily meet this demand while providing significant cost savings over cylinder gas.

Sample Preparation and Storage

Nitrogen is extensively used to create inert atmospheres for sample prep and long-term storage of sensitive materials, preventing oxidation and degradation. Applications include:

- Solvent Evaporation: Nitrogen streams are used to gently evaporate solvents without heating, preserving volatile analytes.
- Glove Boxes: Maintaining low-oxygen environments for handling air-sensitive compounds.
- Sample Storage: Purging sample vials or storage containers with nitrogen to extend sample stability.

The ability to produce nitrogen on-demand is particularly valuable for these applications, as it allows for flexible use without concerns about gas availability.

→ Case Study: Multiple Dry Evaporators Supplied by Nitrogen Generator

→ Case Study: Environmental Pollutant Tracing Aided by Nitrogen Generator

Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Ultra-high purity nitrogen is used as a plasma support gas in some ICP-MS systems. It can also be used for:

- Collision/Reaction Cells: To reduce polyatomic interferences.
- Nebulizer Gas: In some specialized applications.

While argon is more commonly used in ICP-MS, nitrogen can offer cost advantages in certain applications, particularly when an on-site generator is available.

Fourier Transform Infrared Spectroscopy (FTIR)

Nitrogen is used to purge FTIR spectrometers, removing atmospheric CO2 and water vapor that can interfere with spectra. A constant, low-flow supply of dry nitrogen is ideal for this application, making on-site generators a perfect fit.

Nuclear Magnetic Resonance (NMR) Spectroscopy

While liquid nitrogen is typically used for cooling NMR magnets, gaseous nitrogen from generators can be used for:

- Sample Spinning: To achieve uniform magnetic field exposure.
- Probe Temperature Control: In variable temperature experiments.

Elemental Analysis

Nitrogen generators can supply carrier gas for certain types of elemental analyzers, particularly those using thermal conductivity detectors (TCD).

Atomic Absorption Spectroscopy (AAS)

In flame AAS, nitrogen can be used as a sheath gas to protect the flame from surrounding air, improving stability and sensitivity for certain elements.

By providing a reliable, cost-effective source of high-purity nitrogen, on-site generators have become a valuable asset in analytical laboratories, improving workflow efficiency and experimental consistency across a wide range of techniques.

Selecting the appropriate nitrogen generator for your laboratory is a critical decision that can significantly impact your operations. Here are key factors to consider:

Flow Rate Requirements 

Determine the total nitrogen consumption across all applications in your lab. Consider:

- Peak demand periods
- Potential for future expansion
- Simultaneous use of multiple instruments

It's generally advisable to choose a generator that can produce 20-30% more than your current peak demand to allow for growth and ensure consistent supply during high-usage periods.

Purity Requirements

Different applications require different nitrogen purities:

- GC carrier gas: typically 99.999% (5.0) or higher
- LC-MS: often 99.5% to 99.999% depending on the system
- Sample preparation: may only require 97-99% purity

Choose a generator that can meet your highest purity needs, or consider multiple generators if you have widely varying purity requirements.

Pressure Requirements

Ensure the generator can deliver nitrogen at the pressure needed for your applications. Most analytical instruments require pressures between 60-100 psi, but some may have higher demands.

Maintenance Requirements

Understand the routine maintenance needs of the generator:

- Frequency of filter changes
- Lifespan of key components (e.g., membranes, molecular sieves)
- Availability and cost of spare parts
- Manufacturer support and service options

Space and Installation Considerations

Evaluate the available space in your laboratory. Consider:

- Footprint of the generator
- Additional space for maintenance access
- Proximity to point of use (shorter tubing runs are preferable)
- Ventilation requirements, especially for heat dissipation

Noise Levels

If the generator will be installed in or near working areas, consider noise output. Some generators are designed for quieter operation, which can be crucial in laboratory environments.

Control and Monitoring Features

Look for generators with advanced control systems that offer:

- Remote monitoring capabilities
- Data logging for quality control
- Alarm systems for purity or pressure deviations
- Integration with laboratory management systems

Redundancy and Backup Options

Consider whether you need built-in redundancy or a backup supply for critical applications. Some options include:

- Dual generator systems
- Automatic switchover to cylinder backup 
- Buffer tanks for short-term supply during maintenance

Energy Efficiency and Operating Costs

Compare the energy consumption of different models. While a more efficient generator may have a higher upfront cost, it can lead to significant savings over time. Consider:

- kWh consumption per cubic meter of nitrogen produced
- Standby power usage
- Potential for heat recovery systems in larger installations

Total Cost of Ownership

Look beyond the initial purchase price and consider:

- Installation costs
- Expected lifespan of the system
- Annual maintenance costs
- Potential energy savings compared to current gas supply methods

Compliance and Certifications

Ensure the generator meets relevant safety standards and has appropriate certifications for your industry (e.g., FDA compliance for pharmaceutical labs).

By carefully evaluating these factors, you can select a nitrogen generator that not only meets your current needs but also provides the flexibility to accommodate future growth and changes in your analytical processes.

Installation and Integration

Proper installation and integration of a nitrogen generator are crucial for maximizing its benefits and ensuring smooth laboratory operations. Here's a detailed look at the key considerations:

Site Preparation

Before installation, assess and prepare the site:

→ Installing a Nitrogen Generator for Sample Preparation

Electrical Requirements: Ensure adequate power supply, typically 220V or 480V for larger systems. Consider installing a dedicated circuit for the generator.

Compressed Air Supply: If using an existing air compressor, verify its capacity and air quality. The air should be oil-free and dry.

Ventilation: Provide proper ventilation to dissipate heat generated by the system. In some cases, additional cooling may be necessary.

Flooring: Ensure the floor can support the weight of the generator and any associated equipment.

Access: Plan for easy access for maintenance and potential future expansion.

Piping and Distribution

Proper gas distribution is essential:

- Use appropriate materials for nitrogen piping, such as stainless steel or copper.
- Minimize the length of piping runs to reduce pressure drops.
- Install shut-off valves at strategic points for maintenance and safety.
- Consider a ring main system for large laboratories to ensure consistent pressure across multiple points of use.
- Implement proper labeling and color-coding of nitrogen lines according to safety standards.

Instrument Connectivity

Ensure compatibility with existing laboratory equipment:

- Verify pressure and flow requirements for each instrument.
- Install appropriate regulators and flow controllers at each point of use.
- Consider installing purity sensors at critical points to monitor gas quality.
- For sensitive instruments, install final filters at the point of use to ensure ultra-high purity.

Performance Optimization

Once installed, optimize the system for peak efficiency:

- Conduct a thorough commissioning process, including leak tests and purity verification.
- Calibrate flow meters and purity analyzers.
- Set up data logging to track performance over time.
- Train laboratory staff on proper operation and basic troubleshooting.

Integration with Lab Management Systems

Modern nitrogen generators can often be integrated with broader laboratory management systems:

- Set up remote monitoring capabilities to track generator performance.
- Integrate alarms with laboratory notification systems.
- Implement automated record-keeping for regulatory compliance.

Safety Considerations

Implement necessary safety measures:

Install Oxygen Depletion Sensors: In enclosed areas where nitrogen is used or stored, these sensors can alert staff to potentially dangerous levels of nitrogen that could displace oxygen and create an asphyxiation hazard.

Training: Provide proper training on the risks associated with nitrogen use and generator operation. Ensure that all staff are familiar with emergency shutdown procedures and the location of safety equipment.

Emergency Protocols: Establish clear emergency protocols, including evacuation procedures and first aid responses for potential exposure to high nitrogen concentrations.

By carefully planning and executing the installation and integration process, laboratories can ensure their nitrogen generator operates efficiently, safely, and in harmony with existing systems and workflows.

Maintenance and Troubleshooting

Proper maintenance is key to ensuring the longevity and reliability of your nitrogen generator. Here's a comprehensive guide to maintenance procedures and troubleshooting common issues:

Routine Maintenance

1. Daily Checks:

- Monitor output pressure and flow rates.
- Check for any unusual noises or vibrations.
- Verify that condensate drains are functioning properly.

2. Weekly Tasks:

- Inspect pre-filters for signs of contamination or damage.
- Check system for any air leaks.
- Clean exterior of the unit to prevent dust accumulation.

3. Monthly Procedures:

- Replace inlet air filters.
- Check and clean condensate drains.
- Verify calibration of oxygen analyzers.

4. Quarterly Maintenance:

- Conduct a thorough leak test on the entire system.
- Inspect and clean heat exchangers if applicable.
- Check electrical connections for any signs of wear or looseness.

5. Annual Service:

- Replace all filters, including coalescing and carbon filters.
- For PSA systems, check the condition of molecular sieve beds.
- For membrane systems, inspect membrane modules for signs of degradation.
- Conduct a comprehensive performance test, including purity analysis across the flow range.

Common Issues and Solutions

1. Decreased Nitrogen Purity:

- Potential Causes: Air leak in the system, degraded membranes or sieve beds, contaminated inlet air.
- Solutions: Conduct a leak test, check inlet air quality, consider replacing membranes or sieve material if old.

2. Reduced Flow Rate:

- Potential Causes: Clogged filters, insufficient inlet air pressure, worn compressor.
- Solutions: Replace filters, check and adjust inlet air pressure, service the air compressor.

3. Excessive Noise or Vibration:

- Potential Causes: Loose components, worn bearings, issues with the air compressor.
- Solutions: Tighten any loose fittings, inspect and replace worn parts, service the compressor.

4. High Dewpoint in Output Nitrogen:

- Potential Causes: Faulty dryer, saturated desiccant, leak in the drying system.
- Solutions: Check and repair the drying system, replace desiccant if necessary.

5. Frequent Cycling or Short Cycling:

- Potential Causes: Incorrect pressure switch settings, leaks in the system, undersized storage tank.
- Solutions: Adjust pressure settings, fix leaks, consider upgrading to a larger storage tank.

When to Seek Professional Service

While many maintenance tasks can be performed in-house, certain situations warrant calling in a professional:

- Any electrical issues or failures.
- Significant and unexplained drops in purity or flow rate.
- Unusual odors or smoke coming from the unit.
- After any major power outages or electrical surges.
- For annual comprehensive servicing and recertification.

Preventive Maintenance Programs:

Many manufacturers offer preventive maintenance programs that include:

- Scheduled visits from trained technicians.
- Priority response for emergency service.
- Discounts on spare parts and upgrades.
- Extended warranty coverage.

Investing in such a program can often be cost-effective, ensuring optimal performance and minimizing downtime.

By adhering to a rigorous maintenance schedule and promptly addressing any issues that arise, laboratories can ensure their nitrogen generators provide a reliable, high-quality gas supply for years to come.

The field of nitrogen generation is continuously evolving, with new technologies and improvements emerging to meet the changing needs of analytical laboratories. Here are some key trends to watch:

1. Increased Energy Efficiency

- Development of more efficient adsorbent materials for PSA systems, reducing energy consumption.
- Improved membrane technologies with higher selectivity and permeability.
- Integration of energy recovery systems to utilize waste heat from the compression process.

2. Smart Technology Integration

- Implementation of IoT (Internet of Things) capabilities for real-time monitoring and predictive maintenance.
- AI-driven optimization of generator performance based on usage patterns and environmental conditions.
- Integration with laboratory automation systems for seamless operation and data management.

3. Miniaturization

- Development of compact, high-performance generators for space-constrained laboratories.
- Modular designs allowing for easy scalability as laboratory needs change.

4. Sustainability Initiatives

- Use of eco-friendly materials in generator construction.
- Development of generators with lower carbon footprints.
- Integration with renewable energy sources, such as solar panels, for off-grid or energy-neutral operation.

5. Multi-Gas Generation

- Systems capable of producing multiple high-purity gases (e.g., nitrogen, oxygen, and zero air) from a single unit.
- Customizable gas mixtures for specialized applications.

6. Enhanced Purity Levels

- Advancements in purification technologies to achieve ultra-high purity levels (99.99999%+) more efficiently.
- Development of specialized purification modules for trace contaminant removal.

7. Noise Reduction

- Implementation of advanced sound-dampening technologies for quieter operation in laboratory environments.

8. User-Friendly Interfaces

- Touch-screen controls with intuitive user interfaces.
- Mobile apps for remote monitoring and control of generator systems.

9. Regulatory Compliance Features:

- Built-in data logging and reporting capabilities to meet evolving regulatory requirements.
- Enhanced security features to prevent tampering and ensure data integrity.

10. Hybrid Systems:

- Combination of PSA and membrane technologies in single units to optimize performance across varying demand profiles.

As these trends continue to shape the industry, analytical laboratories can look forward to nitrogen generators that are more efficient, reliable, and aligned with the evolving needs of modern scientific research.

The adoption of on-site nitrogen generators represents a significant advancement in how analytical laboratories manage their gas supply. By providing a reliable, cost-effective, and environmentally friendly source of high-purity nitrogen, these systems are transforming laboratory operations across various scientific disciplines.

Key takeaways from this guide include:

- The versatility of nitrogen generators in supporting a wide range of analytical techniques.
- Significant cost savings and improved safety compared to traditional gas supply methods.
- The importance of proper selection, installation, and maintenance for optimal performance.
- Exciting future trends that promise even greater efficiency and functionality.

As you consider implementing a nitrogen generator in your laboratory, here are some recommended next steps:

1. Assess Your Current Nitrogen Usage:

- Audit your current nitrogen consumption across all applications.
- Identify peak demand periods and purity requirements.

2. Evaluate Potential Cost Savings:

- Compare the total cost of ownership of a generator to your current gas supply costs.
- Consider both immediate and long-term financial impacts.

3. Consult with Experts:

- Reach out to reputable nitrogen generator manufacturers or suppliers.
- Discuss your specific needs and get personalized recommendations.

4. Plan for Implementation:

- Assess your laboratory space and infrastructure for compatibility.
- Consider any necessary upgrades or modifications to your existing setup.

5. Prepare Your Team

- Educate laboratory staff about the benefits and operation of nitrogen generators.
- Plan for any necessary training on new equipment.

6. Stay Informed

- Keep abreast of new developments in nitrogen generation technology.
- Consider attending industry conferences or webinars on laboratory gas supply solutions.

By carefully considering these factors and taking a strategic approach to implementation, your laboratory can harness the full potential of on-site nitrogen generation, leading to improved efficiency, reduced costs, and enhanced analytical capabilities.

We encourage you to take the next step in optimizing your laboratory's nitrogen supply. Contact us to learn more about selecting the right nitrogen generator for your specific needs and to begin your journey towards more efficient, cost-effective, and sustainable analytical operations.

This comprehensive pillar page provides an in-depth overview of nitrogen generators, addressing the needs and concerns of analytical chemists while offering actionable insights and guidance.