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The combination of per- and polyfluoroalkyl substances (PFAS) testing, trace-level regulatory requirements and complex MS applications can be intimidating. In a recent webinar, now available on demand, SCIEX PFAS expert Craig Butt demonstrated how the new SCIEX 7500+ system can help make PFAS testing easier.

During the webinar, Butt shared the results of a study comparing the robustness of the SCIEX 7500 system and the SCIEX 7500+ system when testing for PFAS in food and answered a variety of questions from attendees. Here, we continue the conversation by providing answers to questions that were not addressed due to time constraints.

Keep reading to learn more about how the SCIEX 7500+ system helps you:

• Achieve data stability in tough matrices over thousands of injections
• Maximize software features
• Ensure you’re fully equipped to address any future challenges related to PFAS testing

You mentioned improved capabilities and performance for the SCIEX 7500+ system. The source removal capability is certainly an advantage, so users can perform routine maintenance themselves. Are there any other advantages from a technical perspective compared to the SCIEX 7500 system?

The SCIEX 7500+ system has 2 key technology features. The first is the Mass Guard technology for enhanced system robustness. The second is the ability to run faster MRM acquisition speeds without sacrificing sensitivity. In other words, the SCIEX 7500+ system can run for longer without the need for maintenance, such as ion rail cleaning, and it can run larger analyte panels without sacrificing data quality.

The data for thousands of continuous injections are impressive. Can you elaborate on the enhanced robustness study and the takeaways for users looking to upgrade their mass spectrometer?

Our initial testing followed the US FDA sample extraction and cleanup procedure for analyzing PFAS in food. After one month of continuous matrix injections, however, the SCIEX 7500 system was still running strong—and the system sensitivity was unaffected! To ensure that the experiment could be completed in a reasonable amount of time, we decided to eliminate the final “polishing” cleanup step by solid phase extraction (SPE) and double the injection volume. This resulted in an accelerated but still customer-relevant testing scheme.

We now know about the robustness and sustainability of the SCIEX 7500+ system regarding sample injections and data acquisition. What about performance quality? How does the new unit compare to the SCIEX 7500 system? 

The SCIEX 7500+ system and the SCIEX 7500 system have the same level of sensitivity and reproducibility. There is no difference with respect to limits of quantitation (LOQs) or analytical precision.

As testing panels get larger and more complex, LC run times are crucial for maintaining fast turnaround times and results generation. Can you expand on the potential benefits of quicker MRM acquisitions and its advantages?

Expanding analyte panels are one of the greatest challenges facing our customers. Very large testing panels typically increase cycle time, even in scheduled methods, resulting in fewer data points across the chromatographic peak and, ultimately, poorer data quality. The SCIEX 7500+ system can run faster MRM acquisition speeds without impacting sensitivity, allowing users to analyze more analytes without sacrificing cycle time, data points across the peak and analytical performance.

Several SCIEX OS software features were highlighted alongside some of the instrument specifications. Can you elaborate on which components of the SCIEX software suite are integral to applications specific to the SCIEX 7500+ system?

The latest version of SCIEX OS software features new capabilities to help users with system tracking, troubleshooting and maintenance. A key feature is the Metrics Tracker, which allows users to chart and monitor performance trends using system calibration and tuning data and QA/QC assay data. Essentially, the Metrics Tracker helps users identify instrument issues early so that corrective action can be taken. Automated, built-in contamination tests are also available for troubleshooting and to help alert users to further maintenance actions.

There are a number of PFAS compounds within the MRMs on this application. What are the main advantages of the SCIEX 7500+ system in terms of PFAS testing? Are there challenging matrices that are now easier to tackle with the SCIEX 7500+ system?

The main advantage of the SCIEX 7500+ system is the enhanced robustness that enables it to tackle dirty matrices without sacrificing sensitivity or uptime. We know that our customers are expanding their PFAS testing beyond drinking water and are now analyzing complex matrices such as wastewater, soils and tissues (e.g., EPA 1633 ). Ultimately this places a higher demand on the instrument and we know that system downtime is one of the most significant costs to a lab. The SCIEX 7500+ system allows our customers to maintain the highest level of analytical performance for longer periods of time.

How about the SCIEX 5500+ system? What is its robustness performance?

We did not perform robustness tests on the SCIEX 5500+ system, primarily because of the long duration of these studies and the intensive resources required. However, the SCIEX 5500+ system has the curtain gas technology that is common to all SCIEX mass spectrometers, which has helped establish SCIEX instruments as leaders in analyzing complex matrices, such as food extracts.

Did your setup include any special PFAS-free kits?

Yes, the LC system used in the study was outfitted with a PFAS kit that contains a delay column to separate the PFAS contaminants leaching from the LC system and PEEK tubing to replace most of the fluoropolymer lines. The kit uses columns and transfer lines from our partners at Phenomenex.

Are there any issues when doing a run with multiple types of food matrices?

Our study tested 4 diverse food extracts: salmon (high protein, high fat), spice (high pigment), avocado (moderate fat, moderate carbohydrate) and pet food (high carbohydrate). The diversity of co-extractable interferences places a high burden on the instrument to maintain system uptime. However, as shown in our study, both the SCIEX 7500 system and the SCIEX 7500+ system showed excellent robustness for these difficult matrices. In particular, the Mass Guard technology of the SCIEX 7500+ system extended its robustness to >6,400 matrix injections.

What are the US FDA regulatory levels for PFAS in vegetables or food? Where can I find a source for this?

Currently, there are no US FDA regulations for PFAS in food, and it is unknown if there will be future regulations.

However, the EU implemented maximum levels for PFAS in certain foods that went into effect on January 1, 2023. To protect consumers, maximum levels were set for perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorohexane sulfonic acid (PFHxS) and for the sum of these 4 PFAS for eggs, fish, meat and other products.

Is SCIEX OS software compatible with all SCIEX LC-MS systems or only newer models?

SCIEX OS software is compatible with all legacy SCIEX instruments, including the QTRAP 4500 system, SCIEX Triple Quad 4500 system, SCIEX 5500+ system, QTRAP 6500+ system and SCIEX Triple Quad 6500+ system. It is also compatible with the SCIEX 7500 system, SCIEX 7500+ system, X500B QTOF system, X500R QTOF system and ZenoTOF 7600 system. However, some software features, such as the Metrics Tracker, are only available for the SCIEX 7500+ system.

Were any other systems in the market tested using the same application to evaluate competitive advantage?

Our study only compared the SCIEX 7500 system and the SCIEX 7500+ system. As far as we know, our work is the most extensive robustness study for PFAS in food extracts.