As the name implies, a micro (or portable) GC is a compact and often mobile GC. They have become popular in recent years as an alternative to standard laboratory GCs in applications where research-grade results are not necessary, thus paving the way for reduced measurement times, and cheaper installation and maintenance. Micro GCs are generally used for niche applications where speed and field use are important, most notably in the oil and gas industry. They are useful for quick evaluation of petroleum stock and for process control in refining or gas processing facilities.

In a standard GC, an analyte is injected with a micro syringe into an inlet system with a temperature high enough to ensure the sample is in a gaseous form, if it is not already. An inert carrier gas, often helium but sometimes hydrogen or nitrogen, carries the analyte through a long column coated with a solid absorbent. As the sample travels through the column, its various chemical components are separated on the basis of their interactions with the absorbent on the column. The nature of this separation is influenced by factors such as flow rate, the nature of the absorbent, the surface area exposed to the carrier gas and the column temperature. As the individual chemical components emerge from the column, the detector obtains a signal and relays the message to the data acquisition system.

As far as the advantages of micro GC go, they are much lighter and therefore portable, use significantly less carrier gas, have much faster analysis times, require far less power consumption, and are simpler and cheaper to operate and maintain. The models currently available also offer useful accessories such as a sample conditioner, gas stream switch valves, a transporting case, rechargeable battery packs and membrane filters.

Still, there are major drawbacks in using micro GC: the injector can only handle samples in the gaseous state, they cannot handle analysis of heavier carbon samples, they operate mostly isothermally with little to no temperature programming ability, and they employ a thermal conductivity detector that lacks sub-ppm sensitivity and is prone to masking analyte components eluting close to the matrix.

Agilent Technologies is the clear market leader with its 490 Micro GC series. A mobile version comes with a field case designed for out-of-lab use and can be controlled with a phone or tablet. For process analysis, Agilent also offers the 490-PRO, which features unattended operation, and on-board data handling and result calculations. These models can be configured with up to four different columns that can run in parallel with their own unique settings. INFICON is the second largest supplier. It offers the Micro GC Fusion, known for its fast analysis and Wi-Fi capabilities.

The market for micro or portable GCs was over $40 million in 2016. Sales have been detrimentally affected in recent years by a weak oil and gas industry, only slightly offset by demand from environmental labs. With the recent uptick in demand from oil refining and the current release of pent-up demand from oil & gas exploration, however, the market for these compact analyzers is expected to grow moderately over the next couple years.

Micro GC at a Glance:

Leading Vendors:

• Agilent Technologies
• INFICON
• Falcon Analytical

Largest Markets:

• Oil and Gas Exploration
• Refining and Natural Gas Processing
• Environmental

Instrument Cost:

• $12,000–$50,000