Triple quadrupole GC/MS systems combine the features of GC and MS to separate, analyze and identify different substances in a sample. After separation by GC, MS detection is based on the analysis of ions moving through a vacuum. Electron impact (EI) is typically the ionization method of choice, while chemical ionization is commonly used as well. Quadrupole mass analyzers consist of four parallel rods through which selected ions are filtered. Ions of various sizes can be selected based on their m/z ratios by changing the DC and RF amplitudes applied to the rods. After the first quadrupole, ions are sent into a gas cell for collision-induced dissociation for further fragmentation. This is known as the “third quadruple.” Next, it is further analyzed by the second quadrupole and then detected.

Triple quadrupole GC/MS analysis is valuable for identifying quantities of target compounds in complex matrices. It is useful for applications in a multitude of areas, including environmental testing, agriculture and food, and forensics and toxicology. In the past, single quadrupole GC/MS was used to identify and quantify contaminants in environmental, agricultural and food samples. However, there is an increasing number of harmful compounds that are potential or proven threats to public health that are present in even smaller amounts and harder to trace than before. For instance, alkylphenols are trace compounds that are endocrine disruptors that can cause cancerous tumors, birth defects and other developmental disorders.

The higher sensitivity of triple quadrupole GC/MS allows for better quantification and detection of trace levels of such compounds. The sensitivity and quantitative capabilities of triple quadrupole GC/MS are also useful in quantifying pesticides in produce. Since food contamination is always a concern, it is useful in meeting the ever-changing and increasing stringencies of food regulations. While LC/MS had been long used for such analyses, a majority of recently developed pesticides are designed to breakdown more rapidly, and have lower molecular weights, making them better suited for GC/MS analysis.

Since its entry into the market in 2008, Agilent Technologies is the leading vendor of triple quadrupole GC/MS systems. There are four different systems found in its 7000 series, and they each make use of the EI method for its ionization source. Thermo Fisher Scientific offers its TSQ Duo GC-MS/MS system, a cost sensitive system that functions as both a single quadrupole and triple quadrupole GC/MS. Bruker has the EVOQ GC-TQ, which uses its compact 436 or 456 GC. Shimadzu entered the market in 2012 with the GCMS-TQ8040, which utilizes its Smart MRM technology.

The total market for triple quadrupole GC/MS was just under $100 million in 2015. The market has been experiencing solid growth over the past several years, driven by strong demand from many end-user markets. In addition, users are migrating from single quadrupole MS to triple quadrupole MS technology.

Triple Quadrupole GC/MS at a Glance:

Leading Suppliers

• Agilent Technologies
• Thermo Fisher Scientific
• Bruker

Largest Markets

• Environmental Testing
• Agriculture and Food
• Forensics

Instrument Cost

• $150,000–$300,000