Markes International (Llantrisant, UK) has announced the launch of Centri®, a fully automated multi-mode sampling and concentration platform for GC–MS.

The new instrument, which was launched at Analytica 2018, builds on Markes’ 20 years of excellence and leadership in the analysis of trace organic chemicals. Centri uses marketing-leading robotics to reliably automate sampling and pre-concentration of volatile and semi-volatile organic compounds (VOCs and SVOCs) through the following sample introduction modes – HiSorb™ high-capacity sorptive extraction, headspace, headspace-trap, SPME, SPME-trap, and thermal desorption.

Analyte flows from all modes can then be concentrated on a sorbent-packed cryogen-free focusing trap, using the same highly successful technology found in Markes’ range of thermal desorption (TD) instruments.

It’s this trapping and valve technology, says Markes’ Technical Marketing Director, Dr Massimo Santoro, that underpins several key advantages of the new system: “As well as enabling ppt-level sensitivity and allowing selective purging of interferents such as water and solvents, the trap and valve design used in Centri allows samples to be split and re-collected onto a clean sorbent tube – a technology that we pioneered at Markes 20 years ago.”

“Since then, we’ve found that many analysts value re-collection because it allows a single sample to be analysed multiple times. This approach brings numerous benefits to Centri now– for example, reduced need to carry out lengthy sample extraction steps to repeat an analysis, greater peace-of-mind by storage of valuable samples, analysis of a wider concentration range by changing the split flow ratios, and easy validation of complete analyte transfer.”

A principal feature of the new platform is that it automates the entire process of sampling, pre-concentration and GC injection for solids, liquids and vapours. As Santoro says, this allows major productivity improvements to be made: “The use of robotics for all operations makes Centri ideal for many laboratories, especially those who are currently struggling with time-consuming manual sample preparation techniques, such as liquid–liquid extraction and solid-phase extraction. With Centri, you can set up a complex sequence of runs for a variety of samples and injection modes, and then literally walk away to get on with other tasks.”

Amongst Centri’s many features is one that is sure to gain the attention of many analysts – the ability to automate high-capacity sorptive extraction from liquids and solids using Markes’ HiSorb™ probes. By using a relatively large volume of PDMS sorbent fixed on a robust and inert metal probe, HiSorb simultaneously allows high sensitivity and robustness to matrix interferences– prominent on the wish-list of many analysts.

Centri can also automate sampling using a number of well-established and widely-used techniques, enabling the analyst to select the best method for their sample. Headspace (HS) and solid-phase micro-extraction (SPME) are popular in many laboratories, and Centri offers the benefits of trap-based focusing and sample re-collection to extend the sensitivity and applicability of these injection methods.

In addition, Centri can desorb industry-standard thermal desorption tubes in compliance with standard methods. These tubes can either be packed with sorbents and used in conjunction with pumped, diffusive or dynamic-headspace sampling, or used to contain small samples of materials and foods, which are then desorbed directly.