The AccuTOF GC-Alpha Mass Spectrometer from JEOL, which was presented at ASMS 69, features flexible ion sources and an MS resolution of 30,000 FWHM.
Due to COVID-19, ASMS 2021 was held as a virtual/in-person hybrid meeting. A total of 112 firms exhibited at ASMS 69, with just over 5,000 people attending between the two meeting options. I shared some technical perspectives last week in Part I of the series, and I conclude in today’s Part II.
Isotope ratio MS requires excellent quantitation with high resolution for mass discrimination between isotopologs. The Delta Q IRMS (Isotope Ratio MS) from Thermo Fisher Scientific is designed to provide rapid discrimination between isotopologs with quantitative analysis.Since the delta mass may be small, high accuracy and precision is essential for data quality and decision support. Cited applications include tracing origin of coffee and wine, sport drug testing to differentiate natural vs. synthetic hormones, and origin of natural gas. Upon adding an LC or GC and software, the system is called the LC IsoLink or GC IsoLink.
The Delta Q IRS is the first product from Thermo’s IsoFootprint program in Bremen, Germany, which has the goal of permanently removing CO2 emissions to zero net by 2030 and company wide by 2050. The inorganic MS product line plans to remove 4500 tons of CO2 by 2026.
Isotopic analysis of uranium is an especially important topic. One report described feeding sample slurries to the inlet orifice of a JEOL AccuTOF, which provided quick analysis. This was used to determine the 235U/238U ratio over the range of 0 to 100 ppm. 140Ce was the internal standard. The technique requires tuning of the AccTOF.
Hybrid Instrument Systems
Switching our focus to GC-MS, JEOL introduced the JMS-T2000GC AccuTOF™GC-Alpha Mass Spectrometer, which features flexible ion sources, some of which bypass the gas chromatograph. The MS part is an MS with resolution of 30.000, mass accuracy of 1 ppm, mass range of 6,000, a dynamic range of 10^4 and detection limit of 18.7 fg.
With the Alpha’s GC, one can chose between electron impact (EI), chemical ionization (CI), pPhoto ionization (PI), and field ion (FI) sources. PI and FI are particularly recommended for qualitative analysis since the soft ionization favors identification of the molecular ion of the analyte. In the direct mode, options include direct injection with direct insertion or exposure probes, field desorption, and field ionization
In LC-MS, the mass spectrometer spends about half the time waiting for the next sample, especially for gradient elution separations. The time required for column regeneration is lost. Shimadzu introduced their Nexera QX which provides Ultra-fast Multiplex of gradient elution separations using LC-MS combined with Shimadzu’s LCMS-8060NX triple quadrupole mass spectrometer. The 8060 platform was upgraded with a new ESI interface, which utilizes proprietary technologies and more efficient ion transfer to further improve speed and detection sensitivity.
The key advance is designing a low dead volume switching valve that provides mobile phase flow to one column while the second column is being regenerated. At the end of the analytical run on the first, the flow path is switched, then the autosampler delivers a new sample to the injection valve and starts the next run on the conditioned column.
The high throughput is supported by the SIL-40 series autosampler fed by up to three plate changers with a total capacity of 17,000 sample wells. Carry over is a key metric of the automated multiplex flow path. A carry-over test result gave only 0.00007%. Elution time performance for the two columns was also measured. The average difference was about 0.02 min on a 2.75 min run.
Waters extended the BioAccord series by adding the ACQUITY Premier, which supports targeted ion assays of biologics, especially those with avidity for metal surfaces. Passivation can reduce analyte loss due to adsorption. For example, assays for analytes with phosphate groups often show trending of results attributed to loss of sample on active sites on the HPLC column. Since phosphorylated protein, peptides and nucleotides are essential in life, Waters developed a the MakPeak HPS surface technology that forms a barrier between metal surface in columns, injector and transfer lines. The results are impressive: a 300% increase in detector sensitivity in glycan profiling and greatly improved chromatographic peak shape and resolution. Peak tailing is reduced for many polar analytes. Columns are suitable for use when installed. This eliminates column conditioning protocols that are often required for polar or chelating analytes. The Premier also provides suggested workflows. The Premier uses a SMARTMS enabled ACQUITY RDa mass detector. The Premier system is designed for high performance consistency from instrument-to-instrument, which increases data quality and supports decision making.
Capillary LC is relentlessly replacing conventional (~4 mm ID column) systems. Thermo Fisher introduced a capillary flow LC-MS platform called the Vanquish Neo UHPLC System. It is optimized for 100 to 300 μm capillary separation columns which reduce flow rate to 10 μL/min or less. The main advantage is improved detection sensitivity, but the Neo UHPLC platform also reduces down-time for detector maintenance. Plus, it is often practical to use high linear velocity in the capillary, which reduces runtime, improving throughput Proportionately.
Additional hyphenated system updates include:
- PerkinElmer introduced the Evolved Gas Analysis system, which uses multiple detectors, including MS. Supported detection (X) includes infrared absorbance (IR) combined with MS or IR-GC/MS. A high-fidelity transfer system moves analytes from the TGA (thermo gravimetric analysis) stage to the various detectors that can be connected in series. PerkinElmer highlighted 12 applications that would find TG-IR-GC/MS a useful instrument system, including nanomaterials, polymer additives and lubricants.
- LECO introduced its Pegasus BT 4D GCxGC TOF-MS. GCxGC is growing in popularity as it resolves complex mixtures, including foods, fuels and formulations. 2D GC is great, but by adding another 2D with MS plus time of flight, one arrives at 4D. The two added dimensions facilitate non-target identification and quantitation enabled by LECO’s NonTarget Deconvolution software. Most of these are qualitative or, at best, semi-quantitative.
- Sciex is part of the Danaher laboratory portfolio, as is Labcyte. Over the last 20 years, Labcyte built a business around acoustic liquid handling, which was used in high throughput screening. But in an example of synergy, Sciex introduced the echo MS system as a sample inlet forESI-LC-MS, or one can drop the LC and get Acoustic Ejection Mass Spectrometry (AEMS), which is capable of 50 times higher sample throughput —a sample per second. Multiplexing can move the needle to three samples/second. Sample-to-sample carry over is usually not detectable. Sciex open software facilitates incorporation of the Echo MS system into existing high throughput screening workflows.
- Several reports cited using beta units of MOBILion’s Systems’ ion mobility instruments, which use SLIM technology to separate complex ions based upon their ion mobility. The SLIM technology provides a long (multimeter) path separation, which improves resolution in a compact benchtop IMS-MS. Detection is with an Agilent 6545XT Q ToF. One poster by Kornal Kedia et. al. used the instrument to characterize isomeric gangliosides.
Columns for LC-MS
IonOpticks makes Aurora UHPLC capillary columns with the nanoZero emitter attached. The emitter is packed to reduce the dead volume. Lengths range from 5 cm to 25 cm with 75 or 150 μm ID packed with 1.6 μm C18 particles. The fitting is leak free at pressure to at least 1200 bar. The firm states it is a trusted partner of Thermo Fisher Scientific and Bruker. A study of 16 capillary columns from different batches showed a %CV of 0.51% for 12 peaks in a tryptic digest.
Software for MS
Bruker Daltonics mines collision cross section (CCS) with Bruker PaSER to improve post run data processing including ion identification. The CCS of the ion is a robust, precise physiochemical property of an ion that extends the primary structure to three-dimensional conformation. PaSER employs deep neural network learning to help improve identification. OligoQuest software and associated workflow is designed for identification of RNA and oligonucleotide therapeutics development. SCiLS Autopilot software is recommended for imaging MS with Bruker’s timsTOF flex X and rapidfireX MALDi platforms. The software is a key enabling technology for the recently introduced timsTOF SCP (Single Cell Protein) and timsTOF Pro2 platforms.
Cerno Bioscience presented two papers that describe how Cerno’s software can provide accurate mass of peaks in the mass spectra obtained from a single quadrupole mass analyzer. The papers are: "Accurate Mass Profile Mode GC/MS Libraries: An Investigation into Alternative Search Strategies" and "Full Spectral Confirmation of Multiply Charged RNA Molecules and Their Modifications with a Single Quadrupole LC/MS System.” The key is the new MassWorks Version 6.1 software platform, which enables accurate mass/spectral accuracy and unknown formula determination on conventional GC/MS or LC/MS single or triple quad instrumentation. Going further, Cerno’s CLIPS formula search technology provides a 100X improvement in mass accuracy. Version 6.1 also supports Bruker TOF-MS mass analyzers.
Mass Photometry: An Orthogonal Alternative to MS for Mega Dalton Particles
ASMS is a meeting focused on mass spectrometry, which is typically limited to ions with a m/z less than a million Da. Yes, there are extreme cases of heavier ions, but these are recognized and newsworthy as pushing the upper limits of the technology. Thus, I was attracted to Mass Photometry (MP) from Refeyn with a tag line “weighing molecules with light.” MP is suitable for measuring molecular mass in the range of 30 kDa to 5MDa.
MP starts with deposition of the analyte molecule on the measurement surface. Using “carefully controlled illumination,” reflected and scattered light is recorded in an instrument called the Refeyn TwoMP, which was recently introduced. The TWO provides a readout of label free particles based upon the image of the light on the surface. Some topics include assessment of purity, homogeneity, protein aggregation and oligomerization, bimolecular interactions including affinity, and time resolved macromolecular complexes.
One example: An application note by Anders Gunnarsson et al. (Astra Zeneca, Gothenburg, SW): “Formation of PROTAC Ternary Complexes measured with mass photometry.” PROTACs are small bifunctional compounds that can selectively bridge a target protein to an E3 ligase, which then is ubiquitated. Ubiquitin marks the protein for destruction by the proteosome. This is a complicated process that requires a balance and order in the binding reactions. The protein targeted for destruction must first bind to the small target identifying ligand, then the binary target complex needs to bind to the E3 ligase that has been conjugated to ubiquitin. Proteosomes then respond to the ubiquitin signal and destroy the target protein. This is a complex therapeutic model that used mass photometry to characterize the concentrations and kinetics of formation of binary and ternary complexes including intermediates.
The 2022 conference, ASMS 70, is scheduled for June 6 to 9, 2022 in Minneapolis, Minnesota. At print time, the meeting is scheduled for in-person attendees, but COVID-19 could change this. Hope to see you there!