Exploring the potential of using ion mobility-mass spectrometry to separate matrix interferences from analytes in food control.

During residue analysis in complex matrices for food safety purposes, interfering signals can sometimes overlap with those of the analyte of interest. Access to an additional separation dimension besides chromatographic and mass separation, such as ion mobility, can aid in removing interfering signals, allowing for correct analyte identification in these cases. In our laboratory, during routine LC-MS/MS analysis of liver samples for growth promoter residues, an interfering signal was found that matches the retention time and m/z values for stanozolol, a synthetic anabolic steroid. In the present work, the performance of a liquid chromatography coupled to ion mobility mass spectrometry (LC-IM-MS) method has been evaluated to study whether this LC-MS/MS false positive in liver samples could be eliminated by LC-IM-MS analysis. A cyclic ion mobility system already allowed the separation of stanozolol from the interfering peak after only one pass, showing a significant improvement compared to the conventional LC-MS/MS method. Additionally, collisional cross section (CCS) values were calculated and successfully compared with those from literature for identification purposes, eventually allowing both the identification and quantification of stanozolol in this complex matrix.

Occurrence of resorcyclic acid lactones in porcine urine: discrimination between illegal use and contamination.

Zeranol (α-zearalanol, α-ZAL), is a resorcyclic acid lactone (RAL). Its administration to farm animals to improve meat production has been prohibited in the European Union due to the potential risk to human health. However, it has been demonstrated that α-ZAL may be present in livestock animals due to Fusarium fungi that produce fusarium acid lactones contamination in feed. The fungi produce a small amount of zearalenone (ZEN), which is metabolized to zeranol. The potential endogenous origin of α-ZAL makes it difficult to correlate positive samples to a potential illicit treatment with α-ZAL. We present two experimental studies that investigated the origin of natural and synthetic RALs in porcine urine. Urine samples from pigs that were either fed with ZEN-contaminated feed or administered α-ZAL by injection were analyzed by liquid chromatography coupled to tandem mass spectrometry, with the method validated according to Commission Implementing Regulation (EU) 2021/808. The data show that although the concentration of α-ZAL in the ZEN feed-contaminated samples is significantly lower than in the illicit administration samples, α-ZAL can occur in porcine urine via natural metabolism. Additionally, the feasibility of using the ratio of forbidden/fusarium RALs in porcine urine as a reliable biomarker for illicit treatment with α-ZAL administration was evaluated for the first time. This study demonstrated that the obtained ratio in the contaminated ZEN feed study was close to 1, while in the illegally administered α-ZAL samples the ratio is always higher than 1 (up to 135). Therefore, this study proves that the ratio criteria (already used when a forbidden RAL is detected in bovine urine) may also be used for porcine urine.

Insights of ion mobility spectrometry and its application on food safety and authenticity: A review.

Ion mobility spectrometry (IMS) is gaining importance in the field of food safety and authenticity in recent years due to its main potential to overcome the challenges that arise from the complexity of food matrices. For many years, IMS has been used as a stand-alone analytical detector due to its quick response, high sensitivity, and portability, and stand-alone applications in food analysis have been explored in recent years. At the same time, IMS hyphenation to mass spectrometry (MS) techniques, usually combined with liquid or gas chromatography (LC/GC), provides an additional dimension to separate isobaric compounds and thus improves method selectivity. Besides, with such ion mobility - mass spectrometry (IM-MS) methods, background noise decreases, increasing method sensitivity, and it provides complementary information to mass spectra and retention time with the collision cross section (CCS). The development of CCS databases within the food safety field would even permit the identification of compounds in non-targeted approaches. Furthermore, it would increase the confidence of control laboratories when determining a sample as non-compliant. Therefore, the number of applications by IMS on food safety and authenticity has increased remarkably in recent years. This review provides the general insights of IMS with the current state and recent approaches for its performance improvement and a general outlook of its applicability in food safety and authenticity.

Ultra-high-performance liquid chromatography-atmospheric pressure ionization-tandem mass spectrometry method for the migration studies of primary aromatic amines from food contact materials.

This work describes the development of an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of 23 primary aromatic amines (PAAs) that can potentially migrate from food contact materials. The chromatographic separation was performed in a pentafluorophenylpropyl (PFPP) column achieving the separation of all PAAs in less than 6.5 min using water to acetonitrile (0.1% acetic acid in both solvents) as mobile phase and a gradient elution. The feasibility of atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) was evaluated as alternative to electrospray ionization (ESI) for the analysis of PAAs. Results showed that for most of the compounds, better responses were obtained with APCI, which shows the advantage of being less susceptible to matrix effects. Tandem mass spectrometry (MS/MS) fragmentation studies of [M + H]+ allowed for the selection of the two most characteristic and abundant product ions of the 23 PAAs which led to the development of a selective and sensitive UHPLC-APCI-MS/MS method with limits of detection ranging from 0.2 to 2 µg kg-1. Moreover, intra-day and inter-day precisions of the method in terms of relative standard deviation (RSD%) were lower than 10% and 15%, while trueness as relative error was <15% for most of the compounds. The UHPLC-APCI-MS/MS method was applied to the analysis of twenty black Nylon kitchenware samples that were submitted to migration tests using food simulant B (3% acetic acid, w/v), and the presence of PAAs were detected in eighteen samples at concentrations above the legislated limit (2 µg kg-1 of food or food simulants).

Simplified screening approach of anabolic steroid esters using a compact atmospheric solid analysis probe mass spectrometric system.

Due to the absence of chromatographic separation, ambient ionization mass spectrometry had the potential to improve the throughput of control laboratories in the last decades and will soon be an excellent approach for on-site use as well. In this study, an atmospheric solids analysis probe (ASAP) with a single quadrupole mass analyzer has been evaluated to identify anabolic steroid esters rapidly. Sample introduction, applied scan time, and probe temperature were optimized for sensitivity. The in-source fragmentations of seventeen selected steroid esters, commonly found in illicit samples, were determined by applying different cone voltages (12, 20, 30, and 40 V). A spectral library was created for these steroid esters based on the four stages of in-source fragmentation spectra. The applicability of this method was demonstrated for the rapid identification of steroid esters in oily injection solutions, providing test results in less than 2 min.

Hand-Held Diode Laser for On-Site Analysis Using Transportable Mass Spectrometry.

A hand-held laser diode thermal desorption electrospray ionization (LDTD-ESI) mass spectrometry (MS) method was developed for rapid screening of illegal substances in solid samples. To achieve that, a simple, inexpensive, battery-powered surgical laser diode at 940 nm was employed to ablate the solid samples. The potential of using a black polytetrafluoroethylene substrate to enhance the analytes' desorption to the gas phase was investigated and demonstrated. Among the optimized ESI parameters, the solvent (methanol/water, 50:50, v/v) and the flow rate (50 µL h-1) were critical to obtain the best sensitivity. The applicability was demonstrated for the rapid identification of selective androgen receptor modulators (SARMs) in pills and powders based on accurate mass measurements by time-of-flight MS. Also, the hand-held LDTD-ESI was combined with a transportable single quadrupole MS. The same SARMs samples were analyzed, and identifications were based on in-source cone voltage fragmentation patterns observed. These initial results demonstrate the applicability of the developed simplified LDTD-ESI MS method for future on-site testing of organic compounds in solid samples.

Pigment profiles of Spanish extra virgin olive oils by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry.

This work studies the natural pigment profiles (chlorophylls and carotenoids) of Spanish Extra Virgin Olive Oils (EVOO) produced in different Spanish regions. The simultaneous qualitative and quantitative analysis of EVOO natural pigments has been performed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) using atmospheric pressure chemical ionisation (APCI). The results showed a similar natural pigment pattern for all the analysed EVOOs, although the total pigments content differed significantly. Moreover, the chlorophyll/carotenoid ratio was close to 1, while the lutein/ß-carotene ratio was higher than 1, showing that lutein is the most abundant carotenoid in the studied Spanish EVOOs. Data from multivariate statistical approach demonstrated that the olive variety does not discriminate between EVOO samples. However, they were classified based on their origin allowing good differentiation of samples from the Basque Country and Canary Islands from the rest of regions. The results of this study show the differences of the nature and pigments concentration of Spanish EVOO samples, parameters that are of significance for reliable characterisation.

Simultaneous analysis of natural pigments and E-141i in olive oils by liquid chromatography-tandem mass spectrometry.

This work describes the development of an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of carotenoids (ß-carotene, lutein, ß-criptoxanthin, neoxanthin, violaxanthin) and chlorophylls, as well as their related compounds (chlorophyll A and B, pheophytin A and B and the banned dyes Cu-pyropheophytin A, Cu-pheophytin A and B) in olive oils. For this purpose, the feasibility of electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the ionization of these compounds was evaluated and compared. Tandem mass spectrometry (MS/MS) fragmentation was discussed for each family of compounds, and the most characteristic and abundant product ions were selected to propose a selective and sensitive UHPLC-MS/MS method. The best results were obtained using APCI and APPI, while ESI provided the worst signal-to-noise ratio (S/N) for all compounds. For the analysis of olive oils, a simple solid-phase extraction (SPE) with silica cartridges was applied before the determination by UHPLC-MS/MS (APCI and APPI) in multiple reaction monitoring (MRM) mode. Method quality parameters were stablished, and the results demonstrate the good performance of the new methods, providing low limits of detection (0.004-0.9 mg L-1), high extraction efficiencies (62-95%) and low matrix effects (< 25%). The developed UHPLC-API-MS/MS (APCI and APPI) methods were applied to the analysis of olive oil samples, and ß-carotene, pheophytin A, pheophytin B and lutein were detected and quantified in all of them at concentrations ranging from 0.1 to 9.5 mg L-1. Graphical abstract.