News from LabRulezLCMS Library - Week 31, 2025

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This week we bring you application notes by Agilent Technologies, Metrohm and Shimadzu and posters by Thermo Fisher Scientific / ASMS and Waters Corporation / ASMS!

1. Agilent Technologies: Quantitation of 18 Per and Polyfluoroalkyl Substances (PFAS) in Shrimp with Agilent LC/TQ 

• Application note
• Full PDF for download

PFAS are a group of anthropogenic chemicals used across various industrial applications and known to enter environmental matrices such as air, soil, and water. Their amphiphilic chemical structure makes them highly soluble in water, which leads to accumulation in animal and human tissues. EU Commission Regulation 2023/915 sets maximum levels for four PFAS in food, including seafood such as crustaceans (Figure 1). In this application note, a highly selective dMRM-based LC/MS method was developed for analysis of residual PFAS analytes in a shrimp matrix using an Agilent 6475 triple quadrupole LC/MS at the required maximum residue limit, as per the EU directive.

This application note presents a highly selective "dynamic multiple reaction monitoring" (dMRM) liquid chromatography/triple quadrupole (LC/TQ) method for the quantitative assessment of 18 PFAS in shrimp, using the Agilent 6475 triple quadrupole LC/MS system. The developed method is found to be linear within the concentration range from 0.1 ng/mL to 2.5 ng/mL with a minimum R2 value of 0.993. A quality control (QC) sample prepared at 0.2 µg/kg with six replicates showed recoveries from 80 to 120%. The relative standard deviation (RSD) of calculated concentrations at QC level in the matrix was found to be below 10%.

Experimental conditions

Instrumentation and methodology 

The instruments used in this experiment included an Agilent 1290 Infinity II high-speed pump (G7120A), Agilent 1290 Infinity II multisampler (G7167B), Agilent 1290 Infinity II multicolumn thermostat (G7116B), Agilent 6475 triple quadrupole LC/MS system, and an Agilent PFC-free HPLC conversion kit (part number 5004-0006). Table 1 details the LC method, and source parameters are listed in Table 2. An intermediate stock of 2 ppm was prepared using MeOH:Water (1:1) as diluent. Further individual dilutions were prepared at 50, 25, 10, 5, and 2 ppb levels for spiking in a blank shrimp matrix to generate prep-spike calibration, as shown in Table 3.

Conclusion 

This application note describes sensitivity values lower than targeted residue limits for PFAS under EU Commission Regulation 2023/915. The recovery values between 80 and 120% at 0.2 µg/kg for 18 PFAS analytes were demonstrated, while matrix calibration from 0.1 to 2.5 µg/kg with the use of a PFC-free HPLC conversion kit makes it more suitable for evaluating samples under future guidelines that cover more analytes in shrimp. Sample preparation using original extraction salt and dispersive solid phase extraction takes less than 1 hour, ensuring a greater number of samples per day. Further, using the Agilent 6475 triple quadrupole LC/MS system for this analysis makes it possible for a routine testing lab to cater to a wider range of prospective food analysis.

2. Metrohm: EIS at different states of charge with INTELLO

• Application note
• Full PDF for download

A battery's state of charge (SOC) represents the percentage of available charge relative to its full capacity, with 100% SOC indicating a fully charged state and 0% SOC a fully discharged one. The SOC is usually estimated by measuring the voltage of the battery, for example 4.2 V might indicate 100% SOC, and 3 V, 0%. Along with a number of other parameters, the internal resistance of a battery varies with SOC, making electrochemical impedance spectroscopy (EIS) a powerful tool for characterizing this relationship. By monitoring resistance across different SOC levels, EIS enables the optimization of material design as well as the tracking of battery aging mechanisms to enhance performance and longevity. This Application Note provides a detailed guide to performing EIS measurements at different states of charge with INTELLO. The fitting and analysis of EIS measurements was done within the fit and simulation tool of NOVA.

EIS is a powerful nondestructive investigative tool for explaining a range of phenomena that can cause damage and premature aging of a battery. One of its key uses is estimating the state of health (SOH) of a battery, which aids in the prediction of the lifetime of that battery.

RESULTS AND DISCUSSION

Note: In the case below, the procedure was adjusted such that the battery was fully charged by a preconditioning cycle before being discharged from 100% SOC in steps of 10% and then charged again in steps of 10%. The analysis and discussion will be focused on the discharge.

The Nyquist plot measured during the discharge steps is shown in Figure 2. The expected features from a battery are seen, including three semi-circles in the mid-frequency region. The situation where the SOC is estimated to be 100% is shown in purple, and where the SOC is expected to be around 10% is shown in orange, with the intermediate plots showing SOC from between these extremes. 

It should be noted that Li-ion batteries are not supposed be discharged regularly to 0% SOC, as over time this can prematurely age the battery. Therefore, most specifications list a discharge cutoff voltage that corresponds to about 10% SOC rather than 0%.

The corresponding Bode plot is shown below in Figure 3. Both plots seem to indicate that only one of the RC time constants is primarily affected by the changing SOC, with the impedance rising as the battery discharges. Based on sources from the literature, it’s likely that this lowest-frequency semicircle corresponds to a slower charge transfer process at the cathode [6,7]. It is logical that the resistance of this process rises as a result of more lithium moving from the anode to be inserted into the cathode. There appears to be either no or very limited change in the contribution to the impedance from the other components in the battery as it is discharged. During the charge portion of the measurement, the opposite effect is seen, with the impedance decreasing as the battery is recharged. Eventually the original Nyquist/Bode plot that was measured at 100% SOC is recovered.

The data above was transferred to and fitted in NOVA, using the equivalent circuit in Figure 4. To obtain a better fit, the non-ideal capacitance was modelled using constant phase elements (CPE). The CDC code for this equivalent circuit is [LR(RQ)(RQ)([RW]Q)], and consists of an inductor element, a series resistance element, and three RQ parallel circuits, with the last also containing a Warburg element in parallel [8]. 

In order to fit the data properly, here are some practical tips. The first is to start from realistic values for the RQ circuits. These were obtained by first doing an electrochemical circuit fit and then pasting the resulting values into the fit and simulation tool. For the inductor, the value was set to 100 nH. The serial resistance was set by reading from the Nyquist plot; in this case it was 60 mOhm. The next tip is to adjust the boundaries (minimum and maximum values) of the fitting to realistic values. For example, for the resistors the boundaries were set to 1 × 10-5 to 5 Ohm. It can also be helpful to fix all three RQ circuits and then release each one in turn. The process of fitting the data allows changes in the Nyquist plot to be made quantifiable.

3. Shimadzu: Extended Evaluation of Method Performance for PFAS & Cyanotoxins Analysis Using a Single LC-MS/MS in Water

• Application note
• Full PDF for download

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in consumer products and industrial applications. Their chemical stability and resistance to degradation have resulted in environmental persistence and accumulation. As a result, regulatory bodies like the US Environmental Protection Agency (EPA) and the European Chemicals Agency (ECHA) are implementing measures to limit their environmental presence¹. 

In the U.S., EPA Methods 537.1 and 533 are approved for quantifying specific PFAS in drinking water using solid-phase extraction (SPE) and LC-MS/MS. Method 537.1 targets 18 PFAS compounds^2,3. Method 533 targets a set of 25 PFAS, including many shorter-chain compounds like ADONA, which are not covered by 537.1. Accounting for the overlap between the two lists, these methods collectively enable the quantification of 30 unique PFAS compounds including GenX and ADONA. 

Beyond PFAS, other drinking water contaminants such as cyanotoxins also pose serious health risks. Cyanobacteria (blue-green algae) are photosynthetic organisms found in freshwater and marine environments. Human-driven nutrient enrichment, especially phosphorus and nitrogen, has led to an increase in Harmful Algal Blooms (HABs) globally. These blooms can produce toxins like cylindrospermopsin, anatoxin-a, and microcystins, which impair water quality and may cause effects ranging from skin irritation to severe illness in humans and animals⁴. 

To address the growing concern over cyanotoxins in drinking water, the US Environmental Protection Agency (EPA) has established analytical protocols—Methods 544 and 545—for their detection in both drinking water and freshwater matrices. EPA Method 544 focuses on the detection of microcystins and nodularin, which are commonly produced by certain species of cyanobacteria⁵. In parallel, EPA Method 545 is designed to target other potent cyanotoxins, specifically cylindrospermopsin and anatoxin-a⁶. Both methods employ liquid chromatography-tandem mass spectrometry (LC-MS/MS) for quantitative analysis.

Method

System configuration: A Shimadzu LCMS-8060RX triple quadrupole mass spectrometer (Figure 1) was utilized for the quantification of PFAS and cyanotoxins in water samples. The system was paired with a Shimadzu LC-40 series front-end liquid chromatography (LC) system, designed for seamless automation, method switching, and high operational efficiency. The configuration included three degassers (one 3- channel and two 5-channel), dual LC-40 solvent delivery pumps with low-pressure gradient (LPGE) modules, an autosampler, a system controller, and a column oven equipped with two switching valves, a 6-port, 2-position valve and a 7-port, 6-position valve. 

To address potential PFAS contamination from LC system solvents and consumables, a delay column was positioned after the solvent mixer and before the autosampler to retain background PFAS away from target analytes. As shown in Figure 2, the system enables automated switching between EPA Methods 533, 544, and 545. For EPA Method 533 (PFAS analysis), the delay column is included in the flow path to reduce background interference. For cyanotoxin analyses (EPA Methods 544 and 545), the delay column is bypassed to prevent cross-contamination, ensuring accurate and reliable results. This flexible configuration enhances both workflow efficiency and analytical versatility on a single LC-MS platform.

Conclusion 

This study demonstrates the successful quantification of PFAS (EPA 533) and cyanotoxins—including microcystins and nodularin (EPA 544), as well as cylindrospermopsin and anatoxin-a (EPA 545)—using a single triple quadrupole mass spectrometer with automatic method switching. This streamlined approach enabled precise and reliable measurements while maintaining high accuracy and sensitivity throughout extended analytical runs, despite multiple injections and frequent method transitions. 

A key advantage of this approach is the efficient switching between analytical methods with only a five-minute rinse between methods. This ensures complete removal of residual analytes and prevents mobile phase contamination, allowing smooth transitions between PFAS and cyanotoxin analysis without compromising data quality. The rapid automatic rinsing process eliminates the need for extensive manual intervention, reducing instrument downtime and increasing overall laboratory productivity. 

By consolidating multiple analytical methods into a single instrument, this approach minimizes the need for separate systems, thereby reducing both capital investment and maintenance costs. This single system enables laboratories with the capability to respond quickly to emergencies, such as HABs, without major disruption of their routine testing, for PFAS and potentially other organic contaminants. Furthermore, automation significantly enhances operational efficiency by minimizing manual labor requirements, improving reproducibility, and optimizing high-throughput sample analysis. This method provides a cost-effective and reliable solution for laboratories performing environmental monitoring and regulatory compliance testing.

4. Thermo Fisher Scientific / ASMS: Enabling up to 270Hz acquisition speed on the Orbitrap Astral Zoom MS 

• Poster
• Full PDF for download

High-throughput experiments demand shorter gradients to analyze more complex samples in a short amount of time. The Thermo Scientific Orbitrap Astral MS acquires up to 200 MS/MS scans per second [1], allowing for sufficient points across the LC peak even at a throughput of 180 samples per day. To further increase this number while maintaining quantitative accuracy, an even higher acquisition rate is highly desired. The Astral analyzer is hereby mostly limited by the switching times of ion optics and the transfer of ions through the instrument. 

We present a new version of the Orbitrap Astral MS, the Thermo Scientific Orbitrap Astral Zoom mass spectrometer (Figure 1) with optimized ion filter and quadrupole components, as well as faster ion transfer to enable higher scan speeds for data independent acquisition (DIA) and datadependent acquisition (DDA) applications. Additional pre-accumulation in the Bent Trap is utilized to improve the overall duty cycle of the instrument (Figure 2).

Results – Settling Times 

The settling times of the ion optical components selecting the precursor mass could be reduced for larger mass jumps from 3 ms (going to higher isolation center) and 4 ms (going to lower isolation center), down to 2.5 ms settling time independent of the direction of the isolation center change (Figure 2). Additionally, a slightly broader region around very narrow variations now benefit from the minimum settling time of 0.6 ms. For Thermo Scientific Orbitrap Astral MS, this minimum settling time could be utilized for m/z jumps < 10 Th while the Orbitrap Astral Zoom MS now utilizes the shortest settling time for window changes up to 15 Th with a linear interpolation in between 15 to 30 Th isolation center changes. The improvements will mostly benefit DDA and targeted applications, and also DIA runs with wider isolation windows. The required settling time depends also on the target isolation center where smaller isolation centers require less time to settle. This could be utilized by adding a m/zdependent settling time.

Conclusions 

The new Orbitrap Astral Zoom MS combines faster settling of ion optics as well as faster transfer of ions through the instrument. Additional pre-accumulation in the bent trap can further be utilized, realizing the following performance: 

• Scan rate of 270 Hz for DIA at 2 ms injection time compared to 220 Hz on the Orbitrap Astral MS. 
• Increase of scan speed for DDA of 20 – 40 Hz depending on the injection time 
• Duty cycle of up to 75% for DIA methods when using pre-accumulation.

5. Waters Corporation / ASMS: Differentiating PFAS Isomers: A Multi-Pass Cyclic Ion Mobility Mass Spectrometry Approach for Detection, Identification, and Relative Quantitation

• Poster
• Full PDF for download

This poster highlights a cutting-edge analytical approach for resolving per- and polyfluoroalkyl substances (PFAS) isomers using multi-pass cyclic ion mobility mass spectrometry (IMS-MS) combined with liquid chromatography (LC). The method enables detection, identification, and relative quantitation of PFAS isomers in complex samples, including technical standards and contaminated drinking water.

Analytical Techniques & Instrumentation

• LC System: Waters ACQUITY I-Class PLUS with PFAS Kit
• Column: CORTECS Premier C18 (2.1 × 100 mm, 2.7 µm)
• MS System: Waters SELECT SERIES Cyclic IMS
  • Ionization: ESI−
  • Resolution: ~60,000 FWHM (MS), ~159 Ω/ΔΩ (IMS with 6 passes)
  • Acquisition: MS/MS in V-mode
  • Software: UNIFI and waters_connect

Experimental Focus

• Target Analytes: PFOS and PFOA isomers from technical mixtures (Wellington Labs) and drinking water (EPA Method 533)
• Approach: LC separation + IMS with multiple passes in a cyclic path to enhance resolution
• Key Challenge: Separation of branched isomers, which are underrepresented in standard methods but valuable for source fingerprinting

Key Results

• 18 PFOS isomers were resolved using LC and multi-pass IMS (7 more than previously reported).
• A ‘Top and Tail’ IMS experiment improved separation of closely related isomers (e.g., branching at C3, C4, C5).
• Drinking water samples showed unique PFOS isomer profiles—potential markers for contamination source tracking.
• Results correlated well with independent 19F NMR data.

Conclusions

• The combination of LC with multi-pass cyclic IMS-MS is a powerful and sensitive tool for resolving PFAS isomer complexity.
• This approach reveals previously undetectable isomers and provides quantitative profiles for source attribution.
• The technique is suitable for both technical standard analysis and environmental monitoring of drinking water.