Small and micro liquid chromatography-mass spectrometry nitrogen generator

Small and micro liquid chromatography-mass spectrometry nitrogen generatorIt is a high-purity, high flow nitrogen supply equipment designed specifically for liquid chromatography-mass spectrometry. As a key auxiliary system of modern analytical laboratory, it provides stable, clean and dry nitrogen for LC-MS through on-site nitrogen production technology, which is used for key functions such as atomizing gas, dry gas and collision gas in electric spray ion source (ESI) or atmospheric pressure chemical ionization source (APCI). Compared with traditional high-pressure nitrogen gas cylinders or liquid nitrogen Dewar evaporation gas supply methods, liquid chromatography-mass spectrometry nitrogen generators have significant advantages such as high safety, low operating costs, continuous gas supply, and small footprint, and have become one of the standard configurations in analytical laboratories.

1Small and micro liquid chromatography-mass spectrometry nitrogen generatorWorking principle

The core of the nitrogen generator for liquid chromatography-mass spectrometry is pressure swing adsorption (PSA) or membrane separation technology. Some models use a combination of the two to meet the strict requirements of LC-MS for high purity (usually ≥ 99.5%, some require ≥ 99.999%), high flow rate (5-30L/min), and extremely low water content (dew point ≤ -70 ℃) of nitrogen.

Air compression and pretreatment: The ambient air is first filtered by a high-efficiency filter to remove particulate matter, and then pressurized to 0.7-1.0MPa by an oil-free air compressor. The compressed air is then passed through a freeze dryer and multi-stage precision filters (including water removal, oil removal, and hydrocarbon removal) to ensure the air quality entering the nitrogen production module.

Nitrogen separation:

PSA technology: utilizing the difference in adsorption capacity of carbon molecular sieves (CMS) for oxygen and nitrogen. Under high pressure, oxygen, water vapor, and carbon dioxide are preferentially adsorbed, while nitrogen passes through; When the molecular sieve is saturated, the system switches to another tower for adsorption, and at the same time, the saturated tower is depressurized, desorbed, and regenerated to achieve continuous nitrogen production.

Membrane separation technology: By utilizing the difference in permeation rates of different gases through hollow fiber membranes, "fast gases" such as oxygen and water vapor are discharged through the membrane wall, while nitrogen is enriched and output as a "slow gas" inside the membrane. This technology has a simple structure and no moving parts, but its purity is usually lower than PSA.

Deep purification and drying: To meet the extreme requirements of LC-MS for trace impurities such as hydrocarbons, moisture, and oxygen, the produced nitrogen gas usually needs to go through a catalytic deaerator (to react residual O? With H? To generate water) and an ultra efficient drying module (such as molecular sieve or permeable membrane dryer), with a final dew point below -80 ℃ and a total hydrocarbon content of<0.1ppm.

Pressure stabilization and transportation: High purity nitrogen is stabilized in a buffer storage tank and transported to LC-MS instruments through clean stainless steel pipelines to ensure pressure fluctuations are less than ± 0.1 bar.

2、 System composition

A complete liquid chromatography-mass spectrometry nitrogen generator typically includes the following modules:

Oil free air compressor: low noise, maintenance free, avoiding oil pollution;

Multi stage air purification system: including primary/high efficiency filters, freeze dryer, activated carbon adsorber;

Nitrogen production core unit: PSA tower group or hollow fiber membrane group;

Deep purification module: catalytic deaerator+ultra drying device;

Gas storage and stabilization system: built-in buffer tank and precision pressure regulating valve;

Intelligent control system: PLC or embedded system, real-time monitoring of pressure, flow rate, dew point, purity, and supports remote alarm and data recording;

Safety protection devices: overvoltage protection, high-temperature shutdown, leakage detection, etc.

3、 Key technical indicators

Nitrogen purity: 99.5% (applicable to most ESI sources) to 99.999% (5N, used for high-sensitivity Orbitrap, Q-TOF, etc.);

Flow range: 5-30L/min (single unit can support 1-2 LC-MS);

Dew point: ≤ -70 ℃, some models can reach -80 ℃;

Residual oxygen:<1ppm (after catalytic deoxygenation);

Total hydrocarbon content:<0.1ppm (to avoid contaminating ion sources);

Noise level:<55dB (A), suitable for laboratory environment;

Power requirements: 220V/50Hz, power 2-5kW