Access Agilent eNewsletter July 2016

Make your Q-TOF LC/MS analyses faster, easier, and more productive—regardless of your application

Aaron Boice, Agilent LC/Q-TOF Product Manager

The daily demands in many laboratories are familiar. Analysts need enhanced detection levels, increased throughput, and rapid development of reliable screening methods. Some labs also require a way to analyze difficult labile compounds. Agilent designed the 6545 Accurate-Mass Q-TOF LC/MS system to meet these needs. The new Agilent Swarm Autotune delivers reproducible femtogram sensitivity, mass accuracy within 800 ppb, and up to five orders of spectral dynamic range. Providing optimization of up to 21 parameters simultaneously, it offers dramatically improved sensitivity for small molecules.

This article describes three recent publications that demonstrate how the Agilent 6545 Q-TOF LC/MS system enables state-of-the-art results across multiple application areas.

Figure 1. Streamlined workflow for genotoxic compound analysis takes advantage of powerful Agilent software tools.

Quickly screen, identify, and quantify potential genotoxic compounds in drugs

Nobody wants toxins in their drugs, but when drug substances are stored for extended periods of time, they may produce potential genotoxic compounds. Detection, identification, and quantification of these compounds can be a time-consuming process. Integrated Agilent hardware platforms and software tools combine to reduce the effort. Agilent Application Note 5991-6378EN describes these tools and demonstrates the routine screening of drugs to identify and quantify potential genotoxic compounds. Figure 1 shows the workflow used in that study.

In this workflow, an Agilent 6545 Q-TOF LC/MS system was implemented to acquire accurate-mass data for samples that contained chlorhexidine as the drug substance. We used Agilent Mass Profiler Professional software to mine the data and compare samples to generate a differential list of compounds. An accurate-mass database search against the differential list identified 4-chloroaniline, a potential genotoxic compound. All Ions MS/MS acquisition mode was used to confirm 4-chloroaniline by MS/MS library matching, and to quantify it using external standards. This workflow is excellent for batch-to-batch sample analysis to detect and quantify known potential genotoxic compounds.

For Research Use Only. Not for use in diagnostic procedures.

Detect trace levels of PPCPs in water – without tedious analyte enrichment

Pharmaceuticals and personal care products (PPCPs) can enter surface waters and can eventually pose a threat to drinking water. Application Note 5991-5954EN describes two methods to screen and quantitate PPCPs in water at part-per-trillion (ppt) levels using the Agilent 6545 Q-TOF LC/MS system. With the Swarm Autotune parameters optimized for small fragile organic molecules, we precisely and accurately screened and quantitated 118 compounds in positive ion mode and 22 compounds in negative mode.

Figure 2. Identify with confidence. 6-acetylmorphine at 25 ppt was detected even though other coeluting ions were 1000 times more abundant.

We selected the high sensitivity slicer mode to maximize instrument sensitivity. Most of the PPCPs were detected without time-consuming analyte enrichment. The simple sample preparation included filtering approximately 3 mL of sample, adding internal standards to a 1.0-mL aliquot of the filtered sample, and injecting 40 μL of sample for analysis by Q-TOF LC/MS. Reporting limits for the majority of analytes were 10 ppt. The limit of detection (LOD) and lower limit of quantitation (LLOQ) for most of the analytes were much less than 10 ppt.

Figure 2 presents an example where we identified 6-acetylmorphine with an overall target score of 93.43 out of 100. This compound was present at only 25 ppt and coeluted with interfering ions that had about 1000-fold greater abundance. Despite these challenges, high-confidence compound identification was achieved based not only on mass accuracy, but also on isotopic abundance and spacing (Figure 2B).

Test for 240 pesticides in food—with improved detection of small molecules

Pesticide residue screening in food products is one of the most demanding applications in food safety. You need fast and reliable analytical methods to quantify pesticides at low concentrations in a broad range of food matrices. Accurate-mass LC/MS meets the challenge because you can easily set up methods to detect a large number of analytes without preliminary knowledge of fragmentation conditions.

Agilent Application Note 5991-5552EN describes a UHPLC/Q-TOF/MS method for the detection of 240 pesticides and pesticide metabolites in difficult food matrices using the Agilent All Ions MS/MS technique. The method takes advantage of the increased chromatographic resolution with the UHPLC capabilities of the Agilent 1290 Infinity LC system, as well as improved ionization with Agilent Jet Stream thermal gradient focusing technology.

Figure 3. Exemplary calibration curves for benalaxyl in black tea matrix (left) and amidosulfuron in avocado matrix (right).

More importantly, the successful screening and quantitation are enabled by both the sensitivity improvement of the Agilent 6545 Q-TOF LC/MS system and tuning for optimal transmission of small fragile organic molecules. Figure 3 shows excellent calibration curves. At the low 10 ng/g spike level, 72 percent of the pesticides were detected in the complex black tea matrix and 80 percent of the pesticides were detected in the high-lipid avocado matrix.

Our results confirmed improved detection of small organic molecules by the Agilent 6545 Q-TOF LC/MS system, thus allowing the screening and quantitation of most of the targeted pesticides below the maximum residue limits (MRLs) specified by regulations.

Get faster answers, better measurements, and easier results

Regardless of your Q-TOF LC/MS application, labs require instrument robustness, uncompromising productivity, and high sensitivity. The Agilent 6545 Q-TOF LC/MS system makes it easier to get the results you need. Learn today how this instrument can streamline your workflows.