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54


February / March 2012


Case study An environmental testing lab, with a high throughput of semivolatile samples, was struggling with the performance of their liners that only lasted for three to five days. The lab switched to ultra-inert splitless single taper liners with wool and immediately extended liner life to seven days. What’s more, stability was excellent and so the lab didn’t have to clip the GC column as often. With the original liners without wool they had to clip daily to achieve passing degradation of endrin/DDT (<20%) insecticide and passing degradation of the plant growth regulator chlorocholine chloride. Using the new liners with wool boosted the analysts’ productivity because they benefited from fewer liner changes, longer column lifetime and less downtime overall. The lab did not previously use liners with wool because active sites on the wool adsorbed many environmental analytes. When the lab compared the performance of the new inert liners with wool to their previous liners they discovered no change in detection limits. The new inert liners outperformed the older liners, particularly with 2,4 dinitrophenol and 4,6-dinitro-2- methylphenol.


Heavy matrix samples with no loss of consistency


The lab was dealing with heavy matrix samples that had a marked effect on the instrument condition every day. This was not an issue for ultra-inert liners, which provided excellent consistency even with heavy matrix samples. The high level of inertness permitted use of glass wool to trap the non-volatiles in the matrix, extending lifetime and protecting the column and the detector.


Sensitive samples with no loss of sensitivity


With the ultra-inert liner with wool there was no loss of sensitivity. Thus, the benefits provided by the new liners with wool, such as homogeneous sample mixing and evaporation, non-volatile residue trapping, and column and detector protection, did not compromise the chromatography or sensitivity of active analytes. This large environmental lab found that the new inert liners delivered consistent levels of inertness for improved detection, greater sensitivity and better peak shapes for challenging active compounds. More importantly, the lab used fewer liners, columns lasted longer, and source cleaning was less frequent, saving them money, and time, and increasing productivity.


phosphorous, or thermionic. Table 1 shows some of the benefits you can expect from using filters to clean your gases.


Clean your GC regularly


If you use heavy matrix samples, such as forensic or environmental, then a strict regime of inspection and replacement to maintain cleanliness is even more important. Table 2 lists some recommended maintenance steps to keep your GC clean and minimise introduction of actives into the flow path.


Summary


In conclusion, it is evident that maintaining a GC inert flow path will become increasingly important, as global regulations become increasingly stringent, and as instruments and chemistries become increasingly sensitive. A flow path is only as inert as the worst performing component, which is why it’s so important to pay attention to every link in the chain. Visit www.agilent.com/chem/ultrainert to learn more about all the components that make up and maintain an inert flow path.


Figure 4: Comparing an inert and stainless steel ion source. The SS source introduces breakdown products


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