An assessment of the impact of extraction and digestion protocols on multiplexed targeted protein quantification by mass spectrometry for egg and milk allergens.

The unintentional presence of even trace amounts of certain foods constitutes a major hazard for those who suffer from food allergies. For many food industries, product and raw ingredient surveillance forms part of their risk assessment procedures. This may require the detection of multiple allergens in a wide variety of matrices. Mass spectrometry offers a possible solution for the quantification of multiple allergens in a single analysis. The capability of MS to quantify many peptides from a complex protein digestion is well known. However, a lack of matrix certified reference materials has made the optimisation of extraction and digestion conditions for multiplexed allergen quantification difficult to assess. Here, we report a systematic study, using preliminary screening followed by a Design of Experiments approach, to find the optimal buffer and digestion conditions for detecting milk and egg protein markers in a model processed food matrix. Five of the most commonly used buffers, two chaotropic reagents and two reducing reagents were assessed for the optimal extraction of multiple protein markers. While the choice of background buffer had little impact, the use of chaotropic and reducing reagents showed significant benefits for the extraction of most proteins. A full factorial design experiment was applied to the parameters shown to have a significant impact on protein recovery. These studies suggest that a single optimal set of extraction conditions enabling the quantitative recovery of all proteins is not easily achieved. Therefore, although MS is capable of the simultaneous quantification of many peptides in a single run, greater consideration of protein extraction is required before these are applied for multiplex allergen quantification in food matrices. Graphical abstract.

Identification and quantification of cannabinoids in Cannabis sativa L. plants by high performance liquid chromatography-mass spectrometry.

High performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) has been successfully applied to cannabis plant extracts in order to identify cannabinoid compounds after their quantitative isolation by means of supercritical fluid extraction (SFE). MS conditions were optimized by means of a central composite design (CCD) approach, and the analysis method was fully validated. Six major cannabinoids [tetrahydrocannabinolic acid (THCA), tetrahydrocannabinol (THC), cannabidiol (CBD), tetrahydrocannabivarin (THCV), cannabigerol (CBG), and cannabinol (CBN)] were quantified (RSD < 10%), and seven more cannabinoids were identified and verified by means of a liquid chromatograph coupled to a quadrupole-time-of-flight (Q-ToF) detector. Finally, based on the distribution of the analyzed cannabinoids in 30 Cannabis sativa L. plant varieties and the principal component analysis (PCA) of the resulting data, a clear difference was observed between outdoor and indoor grown plants, which was attributed to a higher concentration of THC, CBN, and CBD in outdoor grown plants.

Assessment of Beeswax Adulteration by Paraffin and Stearic Acid Using ATR-IR Spectroscopy and Multivariate Statistics-An Analytical Method to Detect Fraud.

A spectroscopic investigation of beeswax adulteration by paraffin and/or stearic acid was undertaken via Attenuated Total Reflectance Infra-Red spectroscopy (ATR-IR) combined with multivariate statistical analyses. Principal Component Analysis (PCA) was successfully applied for the first time as an exploratory tool for the differentiation among pure beeswax and adulterated beeswax by paraffin and stearic acid with detection limits (LOD) of ~5% and 1%, respectively. Partial Least Square (PLS) modelling was used to build chemometric models based on beeswax/paraffin and beeswax/stearic acid calibration mixtures and subsequently used to predict concentrations of paraffin and stearic acid on a set of unknown test samples. PLS predictions demonstrated that beeswax adulteration by paraffin is much more prominent (74%) than the one by stearic acid (26%) and that commercial beeswax products (candles, pearls, blocks, etc.) are more prone to adulteration (27%) than honeycomb-type samples (12.5%).

Optimisation and characterisation of marihuana extracts obtained by supercritical fluid extraction and focused ultrasound extraction and retention time locking GC-MS.

The optimisation of focused ultrasound extraction and supercritical fluid extraction of volatile oils and cannabinoids from marihuana has been accomplished by experimental design approach. On the one hand, the focused ultrasound extraction method of volatile compounds and cannabinoids was studied based on the optimisation of cyclohexane and isopropanol solvent mixtures, and the instrumental variables. The optimal working conditions were finally fixed at isopropanol/cyclohexane 1:1 mixture, cycles (3 s(-1)), amplitude (80%) and sonication time (5 min). On the other hand, the supercritical fluid extraction method was optimised in order to obtain a deterpenation of the plant and a subsequent cannabinoid extraction. For this purpose, pressure, temperature, flow and co-solvent percentage were optimised and the optimal working conditions were set at 100 bar, 35°C, 1 mL/min, no co-solvent for the terpenes and 20% of ethanol for the cannabinoids. Based on the retention time locking GC-MS analysis of the supercritical fluid extracts the classification of the samples according to the type of plant, the growing area and season was attained. Finally, three monoterpenes and three cannabinoids were quantified in the ranges of 0.006-6.2 µg/g and 0.96-324 mg/g, respectively.

Chemometric approach for discriminating tobacco trademarks by near infrared spectroscopy.

Cigarettes are consumer products with a broad market-driven orientation. In order to satisfy the different needs of smokers, cigarette trademarks with different aroma, taste and appearance are available on the market. In this study near infrared (NIR) spectroscopy in combination with chemometrics was applied in order to distinguish cigarette trademarks by analysing the tobacco. Calibration models were developed to differentiate three tobacco trademarks and their respective producers. The developed models also allowed the discrimination of the tobacco according to their geographical origin and may serve as a tool for the detection of counterfeit tobacco.

Spectroscopy applied to feed additives of the European Union Reference Laboratory: a valuable tool for traceability.

Feed additives need to be authorised to be placed on the market according to Regulation (EU) No. 1831/2003. Next to laying down the procedural requirements, the regulation creates the European Union Reference Laboratory for Feed Additives (EURL-FA) and requires that applicants send samples to the EURL-FA. Once authorised, the characteristics of the marketed feed additives should correspond to those deposited in the sample bank of the EURL-FA. For this purpose, the submitted samples were subjected to near-infrared (NIR) and Raman spectroscopy for spectral characterisation. These techniques have the valuable potential of characterising the feed additives in a non-destructive manner without any complicated sample preparation. This paper describes the capability of spectroscopy for a rapid characterisation of products to establish whether specific authorisation criteria are met. This study is based on the analysis of feed additive samples from different categories and functional groups, namely products containing (1) selenium, (2) zinc and manganese, (3) vitamins and (4) essential oils such as oregano and thyme oil. The use of chemometrics turned out to be crucial, especially in cases where the differentiation of spectra by visual inspection was very difficult.

Quantitative Analysis of Bioactive Compounds from Aromatic Plants by Means of Dynamic Headspace Extraction and Multiple Headspace Extraction-Gas Chromatography-Mass Spectrometry.

Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and multiple headspace extraction-gas chromatography-mass spectrometry (MHSE), respectively. The monoterpenes were 1st extracted by means of supercritical fluid extraction (SFE) and analyzed by an optimized DHS-GC-MS. The optimization of the dynamic extraction step and the desorption/cryo-focusing step were tackled independently by experimental design assays. The best working conditions were set at 30 °C for the incubation temperature, 5 min of incubation time, and 40 mL of purge volume for the dynamic extraction step of these bioactive molecules. The conditions of the desorption/cryo-trapping step from the Tenax TA trap were set at follows: the temperature was increased from 30 to 300 °C at 150 °C/min, although the cryo-trapping was maintained at -70 °C. In order to estimate the efficiency of the SFE process, the analysis of monoterpenes in the 4 aromatic plants was directly carried out by means of MHSE because it did not require any sample preparation. Good linearity (r2) > 0.99) and reproducibility (relative standard deviation % <12) was obtained for solid and liquid quantification approaches, in the ranges of 0.5 to 200 ng and 10 to 500 ng/mL, respectively. The developed methods were applied to analyze the concentration of 7 monoterpenes in aromatic plants obtaining concentrations in the range of 2 to 6000 ng/g and 0.25 to 110 µg/mg, respectively.

Differentiation of coccidiostats-containing feed additives by mid and near infrared microscopy.

Coccidiostats belong to the group of feed additives authorised within the European Union exclusively for specific preparations. These preparations not only contain one or more coccidiostats as active substance(s) but also various ingredients such as the carrier, which are included in the European legislation authorising the product. In order to allow the full traceability of the use of feed additives and to check for compliance with legal provisions, there is a strong need for analytical methods that enable the rapid characterisation of these products. This paper describes the applicability of non-destructive techniques such as mid infrared (MIR) and near infrared (NIR) microscopy supported by multivariate analysis for the characterisation of coccidiostats-containing feed additives. The application of these methods demonstrated that different feed additives could be distinguished from each other even when containing the same active substance. The use of chemometrics turned out to be crucial especially in cases where the differentiation of spectra by visual inspection was very difficult.

Resolution of co-eluting compounds of Cannabis Sativa in comprehensive two-dimensional gas chromatography/mass spectrometry detection with Multivariate Curve Resolution-Alternating Least Squares.

Comprehensive Two Dimensional Gas Chromatography - Mass Spectrometry (GC × GC/qMS) analysis of Cannabis sativa extracts shows a high complexity due to the large variety of terpenes and cannabinoids and to the fact that the complete resolution of the peaks is not straightforwardly achieved. In order to support the resolution of the co-eluted peaks in the sesquiterpene and the cannabinoid chromatographic region the combination of Multivariate Curve Resolution and Alternating Least Squares algorithms was satisfactorily applied. As a result, four co-eluting areas were totally resolved in the sesquiterpene region and one in the cannabinoid region in different samples of Cannabis sativa. The comparison of the mass spectral profiles obtained for each resolved peak with theoretical mass spectra allowed the identification of some of the co-eluted peaks. Finally, the classification of the studied samples was achieved based on the relative concentrations of the resolved peaks.

Optimization of comprehensive two-dimensional gas-chromatography (GC×GC) mass spectrometry for the determination of essential oils.

Comprehensive two-dimensional gas-chromatography (GC×GC) is a great tool to explore complex essential oils. In this work the different terpene composition of the aroma fraction of rosemary and oregano were studied. The present investigation is based on the optimization of the comprehensive two-dimensional gas-chromatographic method through the use of experimental designs and Multisimplex, and studying the modulation period, discharge-time and first and second column flows. Making use of a non-polar column (HP-5) in the first dimension and an intermediate one (DB-17) in the second dimension, we concluded that 1.42s, 0.12s, 1.23 mL/min and 17.55 mL/min were our optimum values, respectively. The use of a highly polar phase in the second dimension did not make any significant improvement. Finally, aroma quantification of the studied plants was performed by means of the optimum method achieved and functional groups "bands" were studied. The essential oil concentration ranges obtained were, 0.04-6.6 µg/g for rosemary extracts and 0.04-0.5 µg/g for oregano extracts.