To Switch or Not to Switch? That is the Question.

Aug 23, 2019 | Blogs, Environmental / Industrial, Food / Beverage | 0 comments

Why Polarity Switching Matters

The Basics
In today’s busy analytical laboratories, productivity and high sample throughput are constant demands. More samples need to be analyzed in a shorter timeframe. Laboratories must work to use equipment at its maximum capacity, and methods must be optimized.

With liquid chromatography-mass spectrometry (LC-MS), the chromatography separation has the capacity to resolve a certain number of compounds in a specified period of time. Generally, the shorter the LC run time, the poorer the chromatographic resolution. This potentially affects the MS data quality for those analytes. This is true even for high capacity LC columns, such as those for ultra-high-performance liquid chromatography (UHPLC). 

With an MS detector—let’s say a triple quadrupole MS—you can overcome some of the chromatography shortfalls by using a highly-specific data acquisition method such as Selected Reaction Monitoring (SRM). This is also known as Multiple Reaction Monitoring (MRM) when more than one reaction is involved. The approach allows compounds to be identified and tracked by a specific precursor to product ion transition, or MRM. As the term “multiple” suggests, you can run concurrent compound transitions in virtually the same time frame (within a few milliseconds). Because each transition is unique to a compound, MRM is a highly specific, sensitive, and efficient way of quantifying an analyte.

With a SCIEX triple quadrupole, the unique features of the acquisition software allow the method to be finely optimized to achieve the right number of data points for accurate and precise quantification of chromatographic peaks. This is a feature called Scheduled MRM™ Pro algorithm. It provides a very efficient way of analyzing 100s of analytes within the necessary duty cycle.

The Polarity Question
What if you need a single LC-MS/MS method to analyze compounds with positive and negative ionization states simultaneously? And what if you need to look at both ionization modes while maintaining a high duty cycle, high selectivity, high sensitivity, and chromatographic peak shape integrity?

Well, MS instruments such as the mid-range SCIEX Triple Quad™ 5500+ LC-MS/MS System – QTRAP® Ready or high-end SCIEX Triple Quad™ 6500+ LC-MS/MS System. Both these instruments have detector technology that allows a single method with positive/negative ion switching to run without compromising your data quality.

In the past, MRM conditions were optimized by choosing dwell times that wouldn’t affect the duty cycle of the experiment—which reduced sensitivity and affected detection levels. This generally meant, shorter dwell times for a particular MRM would result in lower accuracy in peak detection and a much higher detection limit.

With the new data acquisition architecture, excellent software algorithms, and powerful electronics, both the SCIEX 5500+ and 6500+ systems can reduce the polarity switching time from 50 milliseconds to 5 milliseconds while maintaining performance characteristics. This ultimately gives an analytical chemist the ability to analyze more compounds in the same amount of time!

See it in action with these workflows:

SCIEX 5500+ System

SCIEX 6500+ System

Plasmid manufacturing: Setting up your CGT programs for success

Plasmid DNA serves a variety of purposes, from critical starting material for proteins, mRNA, viral vectors, and drug substances. Below, Dr. Emma Bjorgum, the Vice President of Client Services of the DNA Business Unit at Aldevron and an expert in plasmid manufacturing, provided insights into the process and an outlook on the future.

Unlocking precision: navigating data conversion in metabolomics

Useful FAQ document to enable researchers to focus on their scientific discoveries and insights rather than the complexities of data management.

Understanding PFAS and its impact on U.S. drinking water

In recent years, per- and polyfluoroalkyl substances (PFAS), often referred to as “forever chemicals,” have become a growing topic of interest due to their persistence in the environment and potential health risks. These synthetic compounds have been widely used in various industrial applications and consumer products since the 1940s. PFAS can be found in the air, soil, and water, and studies have shown that most people have detectable levels of PFAS in their bloodstream. One of the main exposure pathways for humans is through drinking water, particularly in communities located near industrial sites, military bases, or areas where firefighting foam has been used.

Posted by

Ashley Sage is the Senior Manager for Global Portfolio and Technology Strategic Marketing at SCIEX. He is responsible for looking after the strategic marketing campaigns for the product and technology portfolio. Most recently, Ashley was involved in the Generation Quant video creation and campaign. In his free time, Ashley enjoys golfing and spending time with his family.

0 Comments

Submit a Comment

Wordpress Social Share Plugin powered by Ultimatelysocial