Handling multiblock data in wine authenticity by sequentially orthogonalized one class partial least squares.

New approach to deal with food authentication by modelling methods based on data recorded from different sources is proposed and called OC-PLS, combines an orthogonalization step between the different data sets to eliminate redundant information followed by definition of an acceptance area for a target class by OC-PLS. The proposed method was evaluated in two case studies. The first study used a controlled scenario with simulated data. In the second case study, the approach was applied using UV-VIS and IR data, in order to differentiate Slovak Tokaj Selection wines of high quality from other lower market value wines from the Slovak Tokaj wine region. In both cases, better results were reached than when individual blocks of data were achieved. The proposed method proved to be effective in properly exploring common and distinct information in each data block. The best compromise between sensitivity and selectivity in the prediction step was achieved.

Slovak Tokaj wines classification with respect to geographical origin by means of one class approaches.

Tokaj wines could be produced only in so called Tokaj/Tokay wine region that falls within two countries Slovakia and Hungary. Thus, wines bearing Tokaj appellation must be produced only in Hungary and Slovakia by traditional process. Unfortunately, some counterfeit wines from neighbour region in Ukraine could be found in market. The aim of this work is to explore a simple UV-VIS spectrum to recognise true Tokaj/Tokay wines from counterfeits and try to differentiate wines based on their country of origin. This type of question can be duly answered using one class classification approach. Two different approaches, Data Driven Soft Independent Modelling of Class Analogy - DD-SIMCA and One-Class Partial Least Squares - OC-PLS were tested and evaluated for this purpose. In both cases, rigorous way models were built and optimized using only samples of the target class. A set of external samples containing samples from target class and non-target were used to validate the models ability to recognize Slovak samples and reject non-Slovak samples. Model based on DD-SIMCA showed better performance (97% correct rating) compared to OC-PLS models (80% correct rating). Comparing both approaches in terms of sensitivity and specificity, both exhibit high sensitivity (low false negative rate: DD-SIMCA 95% and OC-PLS 100%), however the OC-PLS based model showed low specificity (40%) while DD-SIMCA showed high specificity (100%) rejecting all samples out of Slovak origin. Therefore, the results found in this study show that it is possible to successfully combine UV-VIS spectra and DD-SIMCA models to discriminate Tokaj wine samples of Slovak origin from others. Equally important is environmentally friendly (fast, simple, absence of solvents) classification method in line with green chemistry.

A fast and inexpensive approach to characterize Slovak Tokaj selection wines using infrared spectroscopy and chemometrics.

The Tokaj Selection wines (hungarian equivalent "Aszú") are typical noble sweet wines produced in Tokaj wine region that falls within two countries, Slovakia and Hungary. Taking into account the economic importance and uniqueness of these wines, in this work, a new, fast and inexpensive method that combines infrared spectroscopy and multivariate models for characterization Slovak Tokaj Selection wines was developed. At first, sample authentication via one class models (dd-SIMCA) considered Slovak Tokaj Selection wines as target class. The non-target sample was considered to be only a Tokaj sample of Slovak origin. The resulting model was able to properly recognize samples of the target class with high sensitivity and specificity. Subsequently, the putna index was predicted via PLS models. RMSEP equals 0.44; REPpred of 9.6 and R2 0.95 was found in prediction step.

Volatile composition and enantioselective analysis of chiral terpenoids in Tokaj varietal wines.

The present work compares VOC profiles of 37 Tokaj varietal wines produced from Furmint, Lipovina and Muskát zltý grape varieties determined by SPME-GC-MS. The identified VOCs underwent treatment using one-way ANOVA and PCA for determination of compounds capable to distinguish wines based on grapevine variety. The presence of high concentration of terpenoids was characteristic for Muskát zltý wines, while Furmint and Lipovina expressed quite high similarity, nevertheless Lipovina was characterized by higher relative concentration of 1,1,6-trimethyl-1,2-dihydronaphtalene. Enantioselective analysis of the dominant terpenoids (limonene, linalool, hotrienol and α-terpineol) was performed by heartcut-2D-GC: R form was dominant for limonene and linalool and S enantiomer for hotrienol and α-terpineol. Statistical analysis (ANOVA) confirmed R-linalool as the most significant compound responsible for the main differences between studied varietal wines. LDA identified both total linalool and R-linalool as the only significant (p ≤ 0.05) sorting keys to distinguish investigated varietal wines. Both models allow perfect distinguishing of Muskát zltý from Lipovina and Furmint (p ≤ 0.05) with posterior probability of re-identification 100% but low distinction of Lipovina and Furmint from each other. The probability of posterior re-identification of Lipovina raised from 76.9 to 84.6% and total probability from 86.5 to 89.2% when using dominant enantiomer concentration as sorting variable.

Determination of Ochratoxin A and Ochratoxin B in Archived Tokaj Wines (Vintage 1959-2017) Using On-Line Solid Phase Extraction Coupled to Liquid Chromatography.

According to the EU legislation, ochratoxin A contamination is controlled in wines. Tokaj wine is a special type of sweet wine produced from botrytized grapes infected by "noble rot" Botrytis cinerea. Although a high contamination was reported in sweet wines and noble rot grapes could be susceptible to coinfection with other fungi, including ochratoxigenic species, no screening of Tokaj wines for mycotoxin contamination has been carried out so far. Therefore, we developed an analytical method for the determination of ochratoxin A (OTA) and ochratoxin B (OTB) involving online SPE coupled to HPLC-FD using column switching to achieve the fast and sensitive control of mycotoxin contamination. The method was validated with recoveries ranging from 91.6% to 99.1% with an RSD less than 2%. The limits of quantification were 0.1 and 0.2 µg L-1 for OTA and OTB, respectively. The total analysis time of the online SPE-HPLC-FD method was a mere 6 min. This high throughput enables routine analysis. Finally, we carried out an extensive investigation of the ochratoxin contamination in 59 Slovak Tokaj wines of 1959-2017 vintage. Only a few positives were detected. The OTA content in most of the checked wines did not exceed the EU maximum tolerable limit of 2 µg L-1, indicating a good quality of winegrowing and storing.

Enhancing supercritical fluid chromatographic efficiency: Predicting effects of small aqueous additives.

Supercritical fluid chromatography is becoming more prevalent, particularly in industry. This is due to the inexpensive, and more importantly, environmentally benign carbon dioxide that is used as the major component of the mobile phase. Water is minimally miscible with carbon dioxide at temperatures and pressures commonly used in SFC. However, the introduction of a polar alcohol modifier component increases the solubility of water in carbon dioxide. Previously, the addition of small amounts of water in the mobile phase was shown to provide significant gains in efficiency in chiral supercritical fluid chromatography, especially with polar stationary phases. In this work, we report the effect of the addition of small amounts of water on efficiency and retention factor with four different SFC stationary phases used for achiral analysis namely FructoShell-N (native cyclofructan-6), SilicaShell (bare silica), PoroShell 120 EC C18 (octadecyl silica) and Xselect C18 SB. This is the first reported use of FructoShell-N, a cyclofructan derivatized phase for SFC applications. We devised a predictive test to determine which analytes show an increase in efficiency using their known chemical constants (logKow, pKa, PSA and Hsum). We also use discriminant analysis to elucidate the most important analyte parameters that contribute to "water enhanced" efficiency gains.

Comparison of Different Categories of Slovak Tokaj Wines in Terms of Profiles of Volatile Organic Compounds.

The present work deals with the characterization of volatile organic compounds (VOCs) in wines from the Slovak Tokaj wine region. Studied wine samples were divided into three groups-varietal wines from registered Tokaj vine varieties, film wines Tokajské samorodné dry, and naturally sweet botrytized wines Tokaj selections. The VOCs from wines were extracted using optimized solid phase microextraction (SPME) and analyzed by comprehensive two-dimensional gas chromatography (GC×GC) coupled to high-resolution time-of-flight mass spectrometry (HRTOF-MS). In total, 176 VOCs were identified in all 46 studied samples. It was found that the total number of VOCs in varietal wines was generally higher than in botrytized wines. All three studied categories showed characteristic VOC profiles with significant differences. Varietal wines were characterized by higher concentrations of esters and terpenoids originating from grapes. The presence of γ-octalactone, (E)-6-methylhept-2-en-4-one, and lack of benzaldehyde were typical for Tokajské samorodné dry. Tokaj selections expressed the highest concentration of diethyl malate, benzaldehyde, and furfurals. Several interesting trends were also observed. The concentration of fermentation products was highest in varietal wines, while long-term matured Tokaj special wines were typified by the presence of compounds related to noble-rotten raisins (2-phenylacetaldehyde, ethyl 2-phenylacetate, and 2-phenylethanol), wood (cis-whisky lactone), and aging (1,1,6-trimethyl-2H-naphthalene, furfural, and 5-methylfurfural).

Preparation of citrinin-selective molecularly imprinted polymer and its use for on-line solid-phase extraction coupled to liquid chromatography.

A new selective molecularly imprinted polymer has been prepared and used for extraction in on-line SPE-HPLC to achieve the selective determination of citrinin. Four different imprinted polymers varying in combinations of components were prepared by bulk polymerization and evaluated in terms of binding capacity and selectivity. Imprinted polymer prepared from a mixture comprising 1-hydoxy-2-naphtoic acid as the template molecule, acrylamide as the structural monomer, ethylene dimethacrylate as the cross-linker (in a molar ratio of 1:4:16), and acetonitrile as the porogenic solvent exhibited the best properties. The selectivity of this sorbent was confirmed by comparison with the non-imprinted counterpart prepared using the same polymerization carried out in the absence of template. Imprinted polymer was packed in a 20 × 3 mm i.d. steel cartridge and coupled to the on-line SPE-HPLC system through a six-port switching valve. The method for determination of citrinin including the on-line extraction step was then developed and validated. The sample in the form of methanolic extract was loaded, cleaned, and preconcentrated in the imprinted SPE cartridge. Subsequent separation of citrinin from residual interferences was achieved using the analytical column Kinetex Biphenyl 100 × 4.6 mm i.d., 5 µm particle size, and fluorescence detection (Ex 335, Em 500 nm). The total analysis time was only 9.50 min. Our fully validated method was also applied to analysis of food supplements based on red yeast rice extracts, the control of which is implemented in European legislation. Only minor yet acceptable contamination was found in tested samples.

Determination of dicoumarol in Melilotus officinalis L. by using molecularly imprinted polymer solid-phase extraction coupled with high performance liquid chromatography.

In this work, a method for the extraction of dicoumarol from plant sample utilizing selective adsorbent based on molecularly imprinted polymer was developed. Molecularly imprinted polymer (MIP) was synthesized by bulk polymerization, and on the surface of magnetic particles using dicoumarol as a template, methacrylic acid as functional monomer, chloroform as a porogen, and ethyleneglycol dimethacrylate as a cross-linker. Prepared polymeric materials were evaluated on the base of capacity, selectivity, and morphology. The maximal specific adsoption capacities of the sorbents were 45 µg (for bulk MIP) and 36 µg (for MIP on the magnetic particles) of dicoumarol per 1 g of polymer. An efficiencies of sorption processes of dicoumarol on prepared sorbents were evaluated under various conditions (type of sample solvent, pH, types of washing and elution solvents). The MIP based sorbents were used for solid phase extraction of dicoumarol. Applicability of MIP-SPE coupled to HPLC-DAD was tested for the selective extraction of dicoumarol from sample of sweet clover. The method was linear over concentration range from 1 to 100 µg mL-1 (the correlation coefficient 0.9984) with limit of detection 0.2 µg mL-1. Accuracy of the method was assessed for spiked sample at three concentration levels and recovery values were higher than 84% with relative standard deviation lower than 3.2%.

Recent applications of gas chromatography with high-resolution mass spectrometry.

Gas chromatography coupled to high-resolution mass spectrometry is a powerful analytical method that combines excellent separation power of gas chromatography with improved identification based on an accurate mass measurement. These features designate gas chromatography with high-resolution mass spectrometry as the first choice for identification and structure elucidation of unknown volatile and semi-volatile organic compounds. Gas chromatography with high-resolution mass spectrometry quantitative analyses was previously focused on the determination of dioxins and related compounds using magnetic sector type analyzers, a standing requirement of many international standards. The introduction of a quadrupole high-resolution time-of-flight mass analyzer broadened interest in this method and novel applications were developed, especially for multi-target screening purposes. This review is focused on the development and the most interesting applications of gas chromatography coupled to high-resolution mass spectrometry towards analysis of environmental matrices, biological fluids, and food safety since 2010. The main attention is paid to various approaches and applications of gas chromatography coupled to high-resolution mass spectrometry for non-target screening to identify contaminants and to characterize the chemical composition of environmental, food, and biological samples. The most interesting quantitative applications, where a significant contribution of gas chromatography with high-resolution mass spectrometry over the currently used methods is expected, will be discussed as well.

On-line coupling of molecularly imprinted solid phase extraction with liquid chromatography for the fast determination of coumarins from complex samples.

In this work, an on-line SPE-HPLC method with spectrophotometric detection was developed for the determination of coumarins in complex samples. For the on-line cleanup of samples, a molecularly imprinted polymer was packed into the column cartridge and coupled directly with HPLC (MISPE-HPLC) using a column switching system. The separation of coumarins was performed on a C18 core-shell column (100×4.6mm, 5µm) with a mobile phase consisting of 0.3% acetic acid/acetonitrile with gradient elution at a flow-rate of 1mLmin-1. The total time of the whole analytical run, including the extraction step, was 13.25min. The on-line MISPE-HPLC method was optimized and validated. The results showed good linearity (0.10-100µgmL-1) with correlation coefficients higher than 0.99. The LOD values were from 0.03 to 0.15µgmL-1. The proposed method was successfully applied for analysis of real samples (Cassia cinnamon, chamomile tea, and Tokaj specialty wines) and obtained recoveries varied from 78.7% to 112.2% with an RSD less than 9%.