Rapid Communications in Mass Spectrometry最新文献

Rationale

Agrochemicals are vital for modern agriculture, ensuring high yields and effective pest control. For high-demand products, impurity profiling is crucial, as even trace contaminants can pose serious health and environmental risks. This study analyzes fipronil impurities using advanced techniques to enhance product safety and minimize environmental contamination.

Methods

Impurities in commercial fipronil were separated using high-performance liquid chromatography with a diode array detector (HPLC-DAD, Agilent 1260) at 220 nm on a Phenomenex Luna C18 column (250 × 4.6 mm, 5 μm). Structural elucidation of impurities was performed using liquid chromatography–high resolution mass spectrometry (LC-HRMS) and tandem mass spectrometry (MS/MS) on an Agilent 6545 Q-TOF system with electrospray ionization. Further, impurities were isolated by preparative HPLC (Gemini-NX-5 C18, 250 × 10 mm, 5 μm) and the structures were confirmed using nuclear magnetic resonance (NMR) spectroscopy.

Results

Three impurities were separated by HPLC-DAD, each impurity exhibiting an area percentage greater than 0.1%. LC-HRMS Negative electrospray ionization (ESI) mass spectra of fipronil and its impurities showed dominant [M-H]⁻ ions, allowing precise determination of their exact masses, elemental compositions, and isotopic patterns. Subsequent LC–MS/MS analysis provided detailed fragmentation data to elucidate the structural features of these impurities. Finally, the proposed structures for the studied compounds were confirmed by NMR spectroscopy.

Conclusion

Comprehensive impurity profiling of the widely used insecticide fipronil is studied which is essential for ensuring safety, efficacy, and regulatory compliance. In this, three impurities were identified and structurally characterized using HPLC, LC-HRMS, LC–MS/MS, and NMR. This analytical strategy effectively confirms product purity and supports quality control and risk assessment in agrochemical formulations.

Trial Registration: CSIR-IICT Communication Number: IICT/Pubs./2025/199

Rationale

Inductively coupled plasma (ICP) is a commonly used ion source for mass spectrometry-based chemical analysis of a wide range of materials. Traditional ICP ion sources use high power (> 1000 W) and significant gas flow (> 10 L/min), rendering them unsuitable for spaceflight, as they are too resource-intensive for planetary spacecraft.

Methods

To address the technology gap, we designed and developed a laser ablation microwave-induced plasma mass spectrometer (LA-MIP-MS) and experimentally validated the analytical performance of a prototype instrument capable of providing in situ analyses during planetary science missions. We developed a low-pressure plasma ion source and interfaced it to a heritage quadrupole mass spectrometer (QMS) to perform elemental and isotopic analysis of solid samples via laser ablation. The low power plasma ion source was generated at < 1 Torr (< 133 Pa) using 30 W of power and 50 mL/min of He. Analytes were introduced via laser ablation (266 nm); we report elemental abundances and isotopic ratios for Cu, Ni, and Fe metals.

Results

Our experiments confirmed quantification accuracy for stainless steel within 1.4–4% of values measured by x-ray fluorescence (XRF), with precision ranging from ±9.1 to 22% (2σ_m). Cu and Ni isotopic ratios were measured with ±0.8–3% (2σ_m) precision and reproducibility ranging from 0.12% to 11.8%. Measured limits of detection ranged from 21 ppmw for ⁵⁷Fe to 780 ppmw for ⁵⁴Fe, with limits of detection for Cr, Mn, and Ni below 240 ppmw.

Conclusions

This technique adds to the roster of instrumentation available for planetary missions by enabling elemental and isotopic analysis with orders of magnitude less power and plasma gas relative to commercial ICP-MS systems. This work paves the way for low resource LA-MIP-MS instruments as a viable technique to be applied to a wide range of applications for terrestrial and spaceflight chemical analysis of geologic materials.

Rationale

Rebaudioside A is a predominant steviol glycoside, extracted from Stevia rebaudiana Bertoni leaves and is used as an alternative to sucrose in food and beverages. It undergoes degradation in various conditions, resulting in the formation of degradation products. The identification and characterisation of these degradation impurities are essential for understanding compound stability and product safety, especially the UV-inactive degradation impurities, which are not detected in UV-HPLC by previously reported methods.

Methods

A robust HPLC method was developed and validated using an XBridge BEH amide column with 10 mM ammonium acetate and acetonitrile (20:80% v/v) as the mobile phase, at 1.0 mL/min flow,10 μL injection, and 40 °C column temperature. Degradation products (DPs) formed under acid and base degradation were identified using LC-HRMS/MS. In silico ADME and toxicity profiling were performed using ProTox 3.0 and Pre ADMET. The environmental impact of the method was assessed using the AGREE tool.

Results

The method was linear over 0.10–5.0 mg/mL with LOD and LOQ of 0.025 mg/mL and 0.10 mg/mL, respectively. Five DPs were identified in acid degradation and four DPs were identified under base degradation. The DP-3 was identified as (3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl acetate, which was not reported previously. The toxicity analysis of the degradation impurities showed that the acid DPs were mostly class 4, moderately toxic, except DP-3, which was class 6 and non-toxic, and the entire base DPs were non-toxic. The AGREE tool gave the method a greenness score of 0.75, indicating strong environmental compatibility.

Conclusions

The study provides a valuable understanding of the degradation behaviour of rebaudioside A in various conditions. All the degradation products were identified, including DP-3, which was identified as(3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl acetate. Additionally, in silico toxicity and ADMET studies provided a safety profile of degradation impurities. The AGREE score of the validated method indicates that the developed method is suitable as an environmentally friendly analytical approach.

Rationale

The present study investigated the degradation behaviour of tivozanib (TVZ), a potent tyrosine kinase inhibitor, under various stress conditions, including hydrolytic (acid, base, and neutral), oxidative, thermal, and photolytic (UV and visible light) conditions. The resulting degradation products (DPs) were characterized by LC-Q-TOF-MS/MS and NMR. Additionally, in silico toxicity assessment and mutagenicity studies were accomplished by using DEREK Nexus and SARAH Nexus for TVZ and its DPs.

Methods

The in silico degradation profile of TVZ was predicted using Zeneth software. Separation of the DPs was executed by RP-HPLC with gradient elution mode using Shim-pack Solar C18 column (250 × 4.6 mm, 5 μm). The mobile phase consists of solvent A as 10 mM ammonium acetate buffer (pH 3.8) and solvent B as a mixture of acetonitrile:methanol (70%:30% v/v). Structural characterization was performed for TVZ and its DPs using LC-Q-TOF-MS/MS and NMR spectroscopy.

Results

TVZ was sensitive to hydrolytic (acid, base, and neutral), oxidative, and photolytic (UV light) degradation conditions, wherein seven DPs were observed and separated by RP-HPLC. A plausible degradation pathway of TVZ was proposed based on mass spectrometry data. The preparative HPLC was used to isolate DP-III, DP-IV, and DP-VI, and the structures were confirmed by NMR spectroscopy. Furthermore, the 2D NMR data helped to differentiate the chemical structure of DP-IV, which had the same molecular mass as TVZ.

Conclusion

Forced degradation studies were conducted in accordance with ICH Q1A (R2) and Q1B guidelines. Totally, seven DPs were observed in various stress conditions. DP-IV, a structural isomer of TVZ, was detected in basic hydrolytic conditions. The developed RP-HPLC method was validated following the ICH Q2(R1). This study helps in the stability testing and routine quality control analysis during the formulation development of TVZ.

Rationale

Direct infusion mass spectrometry (DI-MS) is a rapid analytical technique widely used in omics research and other fields. However, the complexity of DI-MS spectra frequently leads to co-fragmentation of analytes with similar m/z, resulting in chimeric fragmentation spectra that complicate compound identification. A DI-based tandem mass spectrometric method (DI-MS2), which modulates the intensity of precursors and fragments by the stepwise movement of the quadrupole isolation window, has been shown to successfully deconvolute chimeric fragmentation spectra. Yet, its applicability to different instruments and optimisation has not been evaluated.

Method

We evaluate the performance of DI-MS2 on two high-resolution instruments: a linear ion trap-Orbitrap (LIT-Orbitrap) and a quadrupole-Orbitrap (Q-Orbitrap). We examined the impact of six instrumental settings, including mass resolving power, isolation window width, step size between MS2 scans, number of microscans, collision energy and automatic gain control (AGC) target, on the analysis of isobaric mixtures with varying m/z differences.

Results

The LIT-Orbitrap consistently achieved high-quality chimeric spectra deconvolution with an average similarity score of 0.98 despite unexpected intensity modulation patterns. The Q-Orbitrap provided four times faster measurements but showed more variable results: It achieved a similarity score of 0.96 for isobars with a m/z difference larger than 0.02, but only 0.56 for m/z differences of 0.006.

Conclusions

These findings indicate that the DI-MS2 is a robust and flexible method applicable across different MS platforms, though the Q-Orbitrap may be less suited for highly complex samples with multiple peaks per nominal mass. This highlights the potential of the DI-MS2 for structural elucidation of complex biological mixtures. Additionally, we provide initial setting optimisation guidelines to improve spectra deconvolution and measurement speed.

Rationale

Flavonoids are phenolic compounds with many health-benefiting properties. However, differentiating different types of flavonoids and their isomers is challenging due to their highly similar structures of various subtypes and different numbers and sites of substituents. Timely quality evaluation of flavonoid-based products is currently almost impossible.

Methods

An ambient ionization method of direct analysis in real time (DART) ion source and tandem mass spectrometry (MS) was used to characterize the fine structures of flavonoids. Different flavonoid subtypes and their isomers with varied numbers and sites of substituents were subjected to DART ionization and collision-induced fragmentation MS analysis.

Results

Seven classes of flavonoids, including methoxy-substituted compounds, exhibited distinctive fragmentation pathways such as retro-Diels-Alder reactions, cross-ring cleavages, and neutral losses. Many flavonoid isomers produced diagnostic MS² and MS³ fragments through DART-tandem MS, enabling direct identification of various isomers within mixtures. An identification workflow was developed, culminating in the creation of a computational tool called FlavoFinder, which automatically determines flavonoid aglycone subtypes and their isomeric structures.

Conclusions

The method and the structural elucidation program were successfully used for the qualitative and quantitative analysis of different flavonoid isomers from real samples. The analysis procedure is high-throughput and is capable of characterizing complex flavonoid structures without extensive sample pretreatment and front-end chromatographic separations.