Archive for the ‘LC-MS/MS’ Category

What can I use as a cap for my mobile phase bottles?

Our choices for mobile phase bottle tops are based primarily on two different products. The first product is the Hub-Cap Bottle Top, catalog #26541. This is designed to fit a 4-Liter solvent bottle. :     The body (also called insert) of the Hub-Cap Top is cap is made of inert PTFE and has three […]

Pesticide analysis for cannabis flower: method and data overview

Pesticides in cannabis has been a hot topic lately and we have been getting many requests for help with this analysis. We did work on pesticide residue testing in cannabis about 6 years ago. At that time, we were limited to testing our methods with a small amount of seized material. Recently, we have been […]

Here’s to HILIC: tailor-made for the MS analysis of polar analytes and highly water-soluble species

There is much discussion these days about Hydrophilic Interaction Chromatography (HILIC) and the options it provides today’s analysts. And there should be.  It’s powerful for analysts working with polar metabolites or highly water-soluble compounds, namely when using MS/MS techniques. Since phase chemistry is Restek’s specialty, and we have designed our Raptor SPP LC column line for […]

7th International Symposium on Recent Advances in Food Analysis (RAFA)

The 7th International Symposium on Recent Advances in Food Analysis, better known in short as RAFA, starts this week in Prague, The Czech Republic.  This is my tenth anniversary for this biennial meeting, where the organizer, Jana Hajšlová, invited me to give the lecture, Using the QuEChERS Sample Preparation Method and GCxGC-TOFMS to Determine Pesticides […]

Analysis of Nicotine and Related Compounds in Urine Using Raptor™ Biphenyl

As Applications Chemists in the LC lab, one of the most exciting parts of our jobs is the variety of analyses we are exposed to. One day you are developing a method for potency analysis in cannabis samples, the next you are looking at anti-epileptic drugs in urine.    We’re regularly challenged to think outside the […]

All of my peaks are tailing… What should I do?

I get quite a few customer questions concerning peak tailing during LC analysis, and how to best troubleshoot this issue.   Peak tailing may be attributed to a variety of different causes including secondary interactions, contamination, column loading, etc.   This list goes on and on.   I usually ask a few key questions, and generally can give […]

Raptor Biphenyl LC Columns provide the data needed for global antibiotic testing

Because the widespread use of preventative veterinary antibiotics has resulted in increased antimicrobial resistance in humans, the US Food and Drug Administration (FDA) released guidelines to address the issue in food animals (December 11, 2013). Similar constraints are also prevalent in the European Union.  Recently, European Researchers1 developed a validated method for the determination of […]

Easy Peasy: Optimized LC-QTRAP Method for Pesticide Residues

Despite what is sometimes advertised, setting up optimized methods for multiresidue pesticide analysis is typically not “easy peasy” and can be quite time consuming. Luckily, some colleagues are willing to share their method with us. Thank you Kelli, James, and Jon!* The downloadable spreadsheet contains retention times, transitions, ionization and collision parameters for our LC […]

Shifting Analyte Retention Times or Matrix Interferences?

Occasionally, we will get a Technical Service call about peak retention times moving during a customer analysis.  Early eluting compounds are especially prone to this shifting, but the issue can often be attributed to matrix interferences that are also not well retained.    Pregabalin and Gabapentin are two antiepileptic drugs typically analyzed by LC-MS/MS.  Because of […]

Mass Overload on Superficially Porous Particles

The benefits of superficially porous particles are without question.  Who wouldn’t want to perform faster separations without the need for expensive UHPLC instrumentation?  It sounds too good to be true.  There must be some drawback – right? The solid, impermeable core present in Raptor™ particles increases column efficiency by decreasing the diffusion path at the […]