Archive for the ‘Optimizing Applications’ Category

An introduction to the benefits of using split injection when performing semivolatiles analysis by 8270D – the instrument checkout mix

This blog is part of a series; the previous installments can be found here and here. We have mentioned several times that the reduced residence time resulting from the fast sample transfer that occurs during a split injection reduces in-inlet degradation and adsorptive loss. Proof of this can be seen in the first run of […]

It May be Hot Outside, but Your Headspace Analysis Can Still Suffer from the Cold

Summer days are my favorite – hot, sunny, and full of fun. But one thing that’s really not fun is trying to track down contamination and/or carryover in your headspace-GC (HS-GC) system. I get questions about this topic pretty regularly, so I thought I would post a blog on the most common culprit for contamination […]

Split Injection Makes for Easier Polar Solvent GC Work versus Splitless Injection

As anyone who’s doing QuEChERS knows, analyzing acetonitrile extracts on nonpolar GC columns (like Rxi-5ms, e.g.) using splitless injection can be problematic because of the classic solvent – stationary phase mismatch.  To avoid split peaks we usually have an initial GC oven temperature slightly above the 82°C boiling point of acetonitrile (MeCN), but this causes tailing […]

Fast Analysis of PAHs using Split Injection and a Short GC Column

Click on the this link:  Fast Analysis of PAHs  to see how I analyzed the EPA 16 polycyclic aromatic hydrocarbons (PAHs) in under 10 min using GC-MS by employing split injection with a Restek Premium Precision split liner with wool and a 15m x 0.25mm x 0.25µm Rxi-5Sil MS GC column.  Split injection allows a higher GC oven […]

Shoot-and-Dilute GC – Practical GC – The Column

Check out my recently published articles in LCGC – The Column on Shoot-and-Dilute GC (split injection GC), where I outline the benefits of this technique through recently collected experimental data in my lab at Restek.  I’m two articles into my Practical GC series, with another one soon to be published.  This is a continuation of other split injection work […]

A quick evaluation of some disadvantages to performing semivolatiles analysis by EPA Method 8270D with splitless injection

This blog is part of a series; the previous installment can be found here. Semivolatile calibrations on the 30 m x 0.25 mm ID x 0.25 µm df column format often range from 1.0 to over 100 ng/µL; however, a 0.25 mm ID column usually experiences peak overload as the mass on column approaches 10 […]

Selecting a Detector for LC

Although a blog is not a good way to teach all there is to know about LC detectors, I have tried to put together information to give an overview of the most common detectors.  Restek does not sell HPLC instruments or detectors, but we think we might be able to help if you are very […]

Comparison between Different Stationary Phases for the Separation of Phthalates using Gas Chromatography-Mass Spectrometry (GC-MS)

Dan Li, Rebecca Stevens, and Chris English Phthalates are widely used as plasticizers in a variety of industry products. However, some phthalates are considered as endocrine disruptors[1] associated with a number of problems, including birth defects[2], high blood pressure in children[3], pregnancy-induced hypertensive heart diseases[4], respiratory problems[5], and obesity[6]. The European Union (EU) and United States Environmental Protection Agency (US EPA) […]

Changing from helium to nitrogen carrier gas in gas chromatography while maintaining separation efficiency and analysis time

In two recent ChromaBLOGraphy posts (see links below) I described the experimental implementation of an idea Jaap de Zeeuw had to use nitrogen carrier gas for GC while maintaining the same separation efficiency and analysis time as what could be achieved by helium carrier gas. Wait, that’s impossible, right?!  Not if you go from a […]

Phthalate Determination by Dual Column Set in Eight Minutes

Dan Li, Rebecca Stevens, Jason Thomas and Chris English If you don’t have a GC-MS for identification of the EPA regulated phthalates, don’t worry! Here we introduce a parallel dual column set for the analysis of regulated phthalates using µECD. As shown in my previous blog , the Rtx-440 column (cat. # 12923) is a […]