Purchasing Tips for Pre-Owned GC-MS

There are a growing number of options for purchasing pre-owned laboratory equipment, including sophisticated instruments such as gas chromatography-mass spectroscopy (GC-MS). Purchasing pre-owned can be a great option for labs looking to get started in GC-MS techniques or increase existing capacity. A good understanding of the sample types, analytes of interest, and instrument components is essential to find the best preowned GC-MS system for your lab’s applications.

Should you consider a pre-owned GC-MS system?

Pre-owned GC-MS can come with significant cost savings, and is an ideal solution for smaller labs planning to expand into this type of analysis without the budget for a new instrument. There are, however, a few things to keep in mind. Namely, the potentially significant cost savings associated with purchasing pre-owned “will be tempered by the need to budget for items normally included in the price of a new unit,” says Peter Stow, president of Isomass Scientific Inc. “For instance, the price of a used unit may include only a 90-day warranty, with shipping and installation charges additional to the base price,” he explains.

There are advantages other than price to consider as well. Rapid technological changes, for example, can make it difficult for labs to find equipment models of the same generation. According to Stow, “for larger laboratories with multiple GCs across many generations, buying pre-owned will give the opportunity to buy a previous generation model that allows commonality of parts and operation with already-owned units.” Stow also notes that a large portion of pre-owned customers are academic labs working with a single instrument and multiple peripherals, who are hoping to increase peripherals utilization.

Select a system designed for your intended applications

With so many options for GC-MS systems, it is critical to consider the samples, analytes, and intended applications. The gas chromatograph consists of three main components: the injector, the column, and the detector. Columns should be selected based on the intended applications—in general, a packed column is better suited to large sample volumes, while a capillary column is recommended for high-sensitivity analyses.

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Mass spectrometers consist of an inlet, a source region, a mass analyzer, and a data system. The nature of the samples and analytes will dictate selection of the ionization method and mass analyzer. In general, soft ionization methods are ideal for biological molecules of large molecular mass (e.g. proteins, peptides) as they result in minimal fragmentation. Alternatively, hard ionization methods produce significant fragmentation and are amenable to specific organic compounds.

Like ionization methods, there are multiple different analyzers to choose from, including quadrupole and time-of-flight (TOF) options. Quadrupole analyzers are generally affordable and offer good reproducibility, whereas TOF analyzers are fast, and have large mass range capabilities.

Ensuring a quality pre-owned purchase

When comparing pre-owned GC-MS systems, there are a few things to look for to ensure a quality purchase. According to Stow, components like wiring and electronics don’t show much physical wear, and it can be difficult to predict if and when they may fail. Moving parts, however, show the greatest wear and should be serviced and replaced during refurbishment. “For the GC, this means replacing seals and O rings in injectors and detectors, and testing and calibration of mass flow controllers,” he explains.

Customers should also ensure they are purchasing from reputable pre-owned sellers and brokers. “Such sellers may have the ability to test a used instrument before sale and be willing to provide a test certificate,” says Stow. If this is not available, he recommends asking the seller if it’s possible to run the instrument prior to purchase, which may be overseen by the buyer or a third-party company.

Pre-owned GC-MS systems can be an excellent alternative to purchasing new, provided labs have a good understanding of the intended applications, and work with reputable pre-owned sellers.