Rapid evaporative ionization mass spectrometry: A survey through 15 years of applications.

Rapid evaporative ionization mass spectrometry (REIMS) is a relatively recent MS technique explored in many application fields, demonstrating high versatility in the detection of a wide range of chemicals, from small molecules (phenols, amino acids, di- and tripeptides, organic acids, and sugars) to larger biomolecules, that is, phospholipids and triacylglycerols. Different sampling devices were used depending on the analyzed matrix (liquid or solid), resulting in distinct performances in terms of automation, reproducibility, and sensitivity. The absence of laborious and time-consuming sample preparation procedures and chromatographic separations was highlighted as a major advantage compared to chromatographic methods. REIMS was successfully used to achieve a comprehensive sample profiling according to a metabolomics untargeted analysis. Moreover, when a multitude of samples were available, the combination with chemometrics allowed rapid sample differentiation and the identification of discriminant features. The present review aims to provide a survey of literature reports based on the use of such analytical technology, highlighting its mode of operation in different application areas, ranging from clinical research, mostly focused on cancer diagnosis for the accurate identification of tumor margins, to the agri-food sector aiming at the safeguard of food quality and security.

Bridging biological and food monitoring: A colorimetric and fluorescent dual-mode sensor based on N-doped carbon dots for detection of pH and histamine.

Rapid and sensitive monitoring of pH and histamine is crucial for bridging biological and food systems and identifying corresponding abnormal situations. Herein, N-doped carbon dots (CDs) are fabricated by a hydrothermal method employing dipicolinic acid and o-phenylenediamine as precursors. The CDs exhibit colorimetric and fluorescent dual-mode responses to track pH and histamine variations in living cells and food freshness, respectively. The aggregation-induced emission enhancement and intramolecular charge transfer result in a decrease in absorbance and an increase in fluorescence, which become readily apparent as the pH changes from acidic to neutral. This property enables precise differentiation between normal and cancerous cells. Furthermore, given the intrinsic basicity of histamine, pH-responsive CDs are advantageous for additional colorimetric and fluorescent monitoring of histamine in food freshness, achieving linearities of 25-1000 µM and 30-1000 µM, respectively, which are broader than those of alternative nanoprobes. Interestingly, the smartphone-integrated sensing platform can portably and visually evaluate pH and histamine changes due to sensitive color changes. Therefore, the sensor not only establishes a dynamic connection between pH and histamine for the purposes of biological and food monitoring, but also presents a novel approach for developing a multifunctional biosensor that can accomplish environmental monitoring and biosensing simultaneously.

MXene/Hydrogel-based bioelectronic nose for the direct evaluation of food spoilage in both liquid and gas-phase environments.

Various bioelectronic noses have been recently developed for mimicking human olfactory systems. However, achieving direct monitoring of gas-phase molecules remains a challenge for the development of bioelectronic noses due to the instability of receptor and the limitations of its surrounding microenvironment. Here, we report a MXene/hydrogel-based bioelectronic nose for the sensitive detection of liquid and gaseous hexanal, a signature odorant from spoiled food. In this study, a conducting MXene/hydrogel structure was formed on a sensor via physical adsorption. Then, canine olfactory receptor 5269-embedded nanodiscs (cfOR5269NDs) which could selectively recognize hexanal molecules were embedded in the three-dimensional (3D) MXene/hydrogel structures using glutaraldehyde as a linker. Our MXene/hydrogel-based bioelectronic nose exhibited a high selectivity and sensitivity for monitoring hexanal in both liquid and gas phases. The bioelectronic noses could sensitively detect liquid and gaseous hexanal down to 10-18 M and 6.9 ppm, and they had wide detection ranges of 10-18 - 10-6 M and 6.9-32.9 ppm, respectively. Moreover, our bioelectronic nose allowed us to monitor hexanal levels in fish and milk. In this respect, our MXene/hydrogel-based bioelectronic nose could be a practical strategy for versatile applications such as food spoilage assessments in both liquid and gaseous systems.

Miniaturized flexible micro-tube plasma ionization source for the effective ionization of non-easily ionizable pesticides in food with liquid chromatography/mass spectrometry.

In this article, we have studied the potential of flexible microtube plasma (FµTP) as ionization source for the liquid chromatography high-resolution mass spectrometry detection of non-easily ionizable pesticides (viz. nonpolar and non-ionizable by acid/basic moieties). Phthalimide-related compounds such as dicofol, dinocap, o-phenylphenol, captan, captafol, folpet and their metabolites were studied. Dielectric barrier discharge ionization (DBDI) was examined using two electrode configurations, including the miniaturized one based on a single high-voltage (HV) electrode and a virtual ground electrode configuration (FµTP), and also the two-ring electrode DBDI configuration. Different ionization pathways were observed to ionize these challenging, non-easily ionizable nonpolar compounds, involving nucleophilic substitutions and proton abstraction, with subtle differences in the spectra obtained compared with APCI. An average sensitivity increase of 5-fold was attained compared with the standard APCI source. In addition, more tolerance with matrix effects was observed in both DBDI sources. The importance of the data reported is not just limited to the sensitivity enhancement compared to APCI, but, more notably, to the ability to effectively ionize nonpolar, late-eluting (in reverse-phase chromatography) non-ionizable compounds. Besides o-phenylphenol ([M - H]-), all the parent species were efficiently ionized through different mechanisms involving bond cleavages through the effect of plasma reagent species or its combination with thermal degradation and subsequent ionization. This tool can be used to figure out overlooked nonpolar compounds in different environmental samples of societal interest through non-target screening (NTS) strategies.

Solution and gaseous phase sensing of formaldehyde with economical triphenylmethane based sensors: a tool to estimate formaldehyde content in stored fish samples.

The use of formalin to preserve raw food items such as fish, meat, vegetables etc. is very commonly practiced in the present day. Also, formaldehyde (FA), which is the main constituent of formalin solution, is known to cause serious health issues on exposure. Considering the ill effects of formaldehyde, herein we report synthesis of highly sensitive triphenylmethane based formaldehyde (FA) sensors from a single step reaction of inexpensive reagents namely 4-hydroxy benzaldehyde and 2,6-dimethyl phenol. The synthetic method also provides highly pure product in bulk quantity. The analytical activity of the triphenylmethane sensor 1 with a limit of detection (LOD) value of 2.31 × 10-6 M for FA was significantly enhanced through induced deprotonation and thereafter a LOD value of 1.82 × 10-8 M could be achieved. To the best of our knowledge, the LOD value of the deprotonated form (sensor 2) for FA was superior to those of all the FA optical sensors reported so far. The mechanism of sensing was demonstrated by 1H-NMR titration and recording mass spectra before and after addition of FA to a solution of sensor 2. Both sensor 1 and sensor 2 exhibit quenching in emission upon addition of FA. A fluorescence study also demonstrates enhancement in analytical activity of the sensor upon induced deprotonation. Then the sensor was effectively immobilized into a hydrophilic and biocompatible starch-PVA polymer matrix which enabled detection of FA in a 100% aqueous system reversibly. Again, quick and effective sensing of FA in real food samples (stored fish) with the help of a computational application was demonstrated. The sensors have significant practical applicability as they effectively detect FA in real food samples qualitatively and quantitatively.

Design and fabrication of La-based perovskites incorporated with functionalized carbon nanofibers for the electrochemical detection of roxarsone in water and food samples.

The pentavalent arsenic compound roxarsone (RSN) is used as a feed additive in poultry for rapid growth, eventually ending up in poultry litter. Poultry litter contains chicken manure, which plays a vital role as an affordable fertilizer by providing rich nutrients to agricultural land. Consequently, the extensive use of poultry droppings serves as a conduit for the spread of toxic forms of arsenic in the soil and surface water. RSN can be easily oxidized to release highly carcinogenic As(III) and As(IV) species. Thus, investigations were conducted for the sensitive detection of RSN electrochemically by developing a sensor material based on lanthanum manganese oxide (LMO) and functionalized carbon nanofibers (f-CNFs). The successfully synthesised LMO/f-CNF composite was confirmed by chemical, compositional, and morphological studies. The electrochemical activity of the prepared composite material was examined using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The obtained results confirmed that LMO/f-CNF showed enhanced electrocatalytic activity and improved current response with a good linear range (0.01-0.78 µM and 2.08-497 µM, respectively), exhibiting a low limit of detection (LOD) of 0.004 µM with a high sensitivity of 13.24 µA µM-1 cm-2 towards the detection of RSN. The noteworthy features of LMO/f-CNF composite with its superior electrochemical performance enabled reliable reproducibility, exceptional stability and reliable practical application in the analysis of tap water and food sample, affording a recovery range of 86.1-98.87%.

Application of graphite carbon black assisted-laser desorption ionization-mass spectrometry for soy sauce product discrimination.

In a previous study, we developed a novel analytical method to directly and simultaneously detect taste- and odor-active compounds using graphite carbon black (GCB)-assisted laser desorption ionization mass spectrometry (LDI-MS). In this study, we aimed to evaluate food quality using a variety of soy sauces using the method to discriminate each product. Graphite carbon black-laser desorption ionization-mass spectrometry allowed the provision of hundreds of MS peaks derived from soy sauces in both positive and negative modes without any tedious sample pretreatments. Principal component analysis using the obtained MS peaks clearly distinguished three soy sauce products based on the manufacturing countries (Japan, China, and India). Moreover, this method identified distinct MS peaks for discrimination, which significantly correlated with their quantitative amounts in the products. Thus, GCB-LDI-MS analysis was established as a simple and rapid technique for food analysis, illustrating the chemical patterns of food products.

Capillary electromigration methods for food analysis and Foodomics: Advances and applications in the period March 2021 to March 2023.

This work presents a revision of the main applications of capillary electromigration (CE) methods in food analysis and Foodomics. Papers that were published during the period March 2021 to March 2023 are included. The work shows the multiple CE methods that have been developed and applied to analyze different types of molecules in foods and beverages. Namely, CE methods have been applied to analyze amino acids, biogenic amines, heterocyclic amines, peptides, proteins, phenols, polyphenols, pigments, lipids, carbohydrates, vitamins, DNAs, contaminants, toxins, pesticides, additives, residues, small organic and inorganic compounds, and other minor compounds. In addition, new CE procedures to perform chiral separation and for evaluating the effects of food processing as well as the last developments of microchip CE and new applications in Foodomics will be also discussed. The new procedures of CE to investigate food quality and safety, nutritional value, storage, and bioactivity are also included in the present review work.

Oilomics: An important branch of foodomics dealing with oil science and technology.

Oil is one of three nutritious elements. The application of omics techniques in the field of oil science and technology is attracted increasing attention. Oilomics, which emerged as an important branch of foodomics, has been widely used in various aspects of oil science and technology. However, there are currently no articles systematically reviewing the application of oilomics. This paper aims to provide a critical overview of the advantages and value of oilomics technology compared to traditional techniques in various aspects of oil science and technology, including oil nutrition, oil processing, oil quality, safety, and traceability. Moreover, this article intends to review major issues in oilomics and give a comprehensive, critical overview of the current state of the art, future challenges and trends in oilomics, with a view to promoting the optimal application and development of oilomics technology in oil science and technology.

Food allergen detection by mass spectrometry: From common to novel protein ingredients.

Food allergens are molecules, mainly proteins, that trigger immune responses in susceptible individuals upon consumption even when they would otherwise be harmless. Symptoms of a food allergy can range from mild to acute; this last effect is a severe and potentially life-threatening reaction. The European Union (EU) has identified 14 common food allergens, but new allergens are likely to emerge with constantly changing food habits. Mass spectrometry (MS) is a promising alternative to traditional antibody-based assays for quantifying multiple allergenic proteins in complex matrices with high sensitivity and selectivity. Here, the main allergenic proteins and the advantages and drawbacks of some MS acquisition protocols, such as multiple reaction monitoring (MRM) and data-dependent analysis (DDA) for identifying and quantifying common allergenic proteins in processed foodstuffs are summarized. Sections dedicated to novel foods like microalgae and insects as new sources of allergenic proteins are included, emphasizing the significance of establishing stable marker peptides and validated methods using database searches. The discussion involves the in-silico digestion of allergenic proteins, providing insights into their potential impact on immunogenicity. Finally, case studies focussing on microalgae highlight the value of MS as an effective analytical tool for ensuring regulatory compliance throughout the food control chain.

Multi-Allergen Quantification in Food Using Concatemer-Based Isotope Dilution Mass Spectrometry: An Interlaboratory Study.

BACKGROUND: Food allergen analysis is essential for the development of a risk-based approach for allergen management and labeling. MS has become a method of choice for allergen analysis, even if quantification remains challenging. Moreover, harmonization is still lacking between laboratories, while interlaboratory validation of analytical methods is necessary for such harmonization. OBJECTIVE: This interlaboratory study aimed to evaluate the potential of MS for food allergen detection and quantification using a standard addition quantification strategy and a stable isotope-labeled (SIL) concatemer as an internal standard. METHODS: In-house-produced test material (cookies), blank and incurred with four allergens (egg, milk, peanut, and hazelnut), allergen standards, an internal standard, and the complete methodology (including sample preparation and ultra-HPLC-MS/MS method) were provided to nine laboratories involved in the study. Method sensitivity and selectivity were evaluated with incurred test material and accuracy with spiked test material. Quantification was based on the standard addition strategy using certified reference materials as allergen protein standards and a SIL concatemer as an internal standard. RESULTS: All laboratories were able to detect milk, hazelnut, and peanut in the incurred cookies with sufficient sensitivity to reach the AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR® 2016.002). Egg detection was more complicated due to food processing effects, yet five laboratories reached the sensitivity requirements. Recovery results were laboratory-dependent. Some milk and hazelnut peptides were quantified in agreement with SMPR 2016.002 by all participants. Furthermore, over 90% of the received quantification results agreed with SMPR 2016.002 for method precision. CONCLUSION: The encouraging results of this pioneering interlaboratory study represent an additional step towards harmonization among laboratories testing for allergens. HIGHLIGHTS: In this pioneering interlaboratory study, food allergens were analyzed by MS with characterized incurred and spiked test materials, calibrated with a certified reference material, and a single SIL concatemer used as an internal standard.

In-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization coupled with high-performance liquid chromatography for conveniently determining three furfurals.

This study presents an in-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization (in-pipette-tip KF-SLE-ISD) method for simultaneous enrichment and derivatization of furfurals. Briefly, 3 mg of natural kapok fiber, which was loaded in an assembled pipette-tip, was used to support 12.5 µL of extractant (ethyl acetate/toluene, 75:25, v/v) containing 10 mM 2,4-dinitrophenylhydrazine. The in-pipette-tip KF-SLE-ISD procedure was conveniently conducted by aspirating/releasing 1 mL of sample solution 10 cycles, allowing simultaneous extraction and derivatization of furfurals. Then, 100 µL of acetonitrile was aspirated/released 5 cycles for elution, 10 µL of which was directly analyzed by high-performance liquid chromatography. The limits of quantitation were in ranges of 0.10-0.45 µg/mL. The method showed satisfied linearity (R2 > 0.99), precision (RSD < 8.53%) and relative recovery (90.34-114.71%), which was successfully applied to determine furfurals in various samples (e.g., honeys, juices and glucose injections). The proposed method has the merits of effectiveness, simplicity, low cost, wide availability and ease of automation.

Padronização de uma PCR multiplex para a detecção de fraude em leite bubalino e caprino por adição de leite bovino / Standardization of a multiplex PCR for detection of fraud in buffalo and goat milk by addition of bovine milk

O consumo de leite de espécies como bubalino e caprino tem se popularizado por representarem uma alternativa para indivíduos que possuem restrições alimentares relacionadas ao leite bovino e em virtude das propriedades nutricionais desses alimentos. No entanto, fatores como a baixa produção e a sazonalidade predispõem a adulterações destes alimentos, principalmente pela adição de leite bovino, visando maior rendimento e lucratividade. Assim, o objetivo do estudo foi padronizar um método de PCR multiplex para autenticação de leites bubalino e caprino. Para isso, amostras de leite exclusivamente de cada espécie foram utilizados para a padronização da técnica. Em seguida, foi realizada a fraude pela adição de leite bovino ao caprino e ao bubalino, em proporções de 0,1% até 100%. A técnica foi eficaz, precisa, rápida e prática para a detecção do DNA de bovino, bubalino e caprino, separadamente e em conjunto. Na fraude experimental, o limite de detecção da técnica ocorreu a partir do menor percentual testado (0,1%) tanto no leite caprino quanto no bubalino. Dessa forma, a PCR multiplex testada mostrou ser uma importante ferramenta para a autenticação de leite, pendendo ser utilizada para fins de fiscalização por órgãos competentes.

Milk consumption of species such as buffalo and goat has become popular due to the nutritional properties of these foods and because they represent an alternative for individuals who have dietary restrictions related to bovine milk. However, factors such as low production and seasonality predispose to adulteration, mainly by the addition of bovine milk, aiming at higher yield and profitability. Thus, the aim of the present study was to standard a multiplex PCR method for buffalo and goat milks authentication. For this, the milks exclusively of each species were used to standardize the technique. Subsequently, fraud was performed by the addition of bovine milk to goat and buffalo in proportions from 0.1% to 100%. The technique was effective and accurate for detecting bovine, buffalo and goat DNA separately and together quickly and practically. In experimental fraud, the detection limit of the technique occurred from the lowest percentage tested (0.1%) in both goat and buffalo milk. Thus, the multiplex PCR tested proved to be an important tool for milk authentication, pending to be used for supervision by competent agencies.

Development and Validation of a Quantitative Method for Multiple Allergen Detection in Food Using Concatemer-Based Isotope Dilution Mass Spectrometry.

BACKGROUND: Accurate food labeling is essential to protect allergic consumers. However, allergen contaminations may occur during the whole food production process. Reliable, sensitive, and robust methods for detecting multiple allergens in food are needed. OBJECTIVE: This work aims to develop and validate an LC coupled to tandem mass spectrometry (MS/MS) method for the detection and quantification of hazelnuts, peanuts, milk, and eggs in processed food products. METHODS: In-house-produced incurred test materials, cookies and chocolates, were used for the method development and validation. The quantification was based on the standard addition strategy using qualified reference materials as allergen protein standards and an innovative stable isotope-labeled concatemer as an internal standard. RESULTS: A method targeting 19 allergen-specific peptides was developed and validated in two laboratories, which strengthens its robustness. The AOAC INTERNATIONAL performance requirements for repeatability, intermediate precision, reproducibility, and recovery were reached for at least one peptide per allergen across both matrixes, and quantification limits complied with the action levels of the Food Industry Guide to the Voluntary Incidental Trace Allergen Labelling (VITAL®) Program Version 3.0. CONCLUSION: The combination of incurred test materials, standard addition strategy, and stable isotope-labeled concatemer as an internal standard allowed us to develop and validate a robust method for detecting and quantifying multiple allergens in food with sufficient sensitivity to protect allergic consumers. HIGHLIGHTS: The combination of characterized incurred test material, calibration with certified reference material, a single stable isotope labelled concatemer and cross-lab validation result in the required standardization and harmonization in food allergen detection according to the stakeholders' group to assess the robustness of our method.

Targeted proteomics for rapid and robust peanut allergen quantification.

This study improves LC-MS-based trace level peanut allergen quantification in processed food by refining method robustness, total analysis time and method sensitivity. Extraction buffer (six compared) and peptide choice were optimised and found to profoundly affect method robustness. A rapid extraction and in-solution digestion method was developed omitting subsequent reduction, alkylation and sample clean-up steps effectively reducing total analysis time from the previously reported ∼5.5-20 h to ∼2.5 h. For the three best performing peptides, accurate quantification (CVs < 15%) with matrix-matched calibration curves (R2 = 0.99-0.97) was achieved for peanut muffin and ice-cream with excellent linearity (0.25-1000 mg kg-1). The best performing peptide enabled excellent recovery rates in ice-cream (106.0 ± 15.1%) and peanut muffin (72.7 ± 13.4%). Sensitivity (LOD = 0.25-0.5 mg kg-1; LOQ = 0.5-1.0 mg kg-1) was 2- to 20-fold improved compared to previous methods depending on the peptide. These methodological improvements contribute to robust peanut detection in food and can be translated to additional food-borne allergens.

Comparative Evaluation of Different Targeted and Untargeted Analytical Approaches to Assess Greek Extra Virgin Olive Oil Quality and Authentication.

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet, with several health benefits derived from its consumption. Moreover, due to its eminent market position, EVOO has been thoroughly studied over the last several years, aiming at its authentication, but also to reveal the chemical profile inherent to its beneficial properties. In the present work, a comparative study was conducted to assess Greek EVOOs' quality and authentication utilizing different analytical approaches, both targeted and untargeted. 173 monovarietal EVOOs from three emblematic Greek cultivars (Koroneiki, Kolovi and Adramytiani), obtained during the harvesting years of 2018-2020, were analyzed and quantified as per their fatty acids methyl esters (FAMEs) composition via the official method (EEC) No 2568/91, as well as their bioactive content through liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) methodology. In addition to FAMEs analysis, EVOO samples were also analyzed via HRMS-untargeted metabolomics and optical spectroscopy techniques (visible absorption, fluorescence and Raman). The data retrieved from all applied techniques were analyzed with Machine Learning methods for the authentication of the EVOOs' variety. The models' predictive performance was calculated through test samples, while for further evaluation 30 commercially available EVOO samples were also examined in terms of variety. To the best of our knowledge, this is the first study where different techniques from the fields of standard analysis, spectrometry and optical spectroscopy are applied to the same EVOO samples, providing strong insight into EVOOs chemical profile and a comparative evaluation through the different platforms.

Purity of Olive Oil Commercially Available in Poland.

The aim of this study was to examine olive oils purchased in Poland for their compliance with label declarations and EEC criteria. Statistical analysis was used to compare the olive oils in terms of their content and composition of essential constituents and color parameters. Fifty olive oils (extra virgin, bioextra virgin, cold-pressed, refined, and pomace) from different countries (Spain, Italy, Greece, Portugal, Germany, France, Israel, and the European Union), were purchased commercially in Poland. The contents of triacylglycerols, sterols, and tocopherols, the fatty acid composition, and the color parameters were determined using chromatographic and spectrophotometric methods. Statistical methods were used to divide the olive oils into clusters. Our results show that the composition and color parameters of olive oils available commercially in Poland, excluding pomace olive oils, are similar. It can thus be concluded that, irrespective of the type of olive oil stated on the label, their quality is the same or very similar.

A rapid phage assay for detection of viable Mycobacterium avium subsp. paratuberculosis in milk.

Paratuberculosis is an incurable gastroenteritis among ruminants that is promoted by Mycobacterium avium subsp. paratuberculosis (MAP), an acid-fast mycobacterium. To accelerate the detection of viable pathogen, a conventional (peptide mediated magnetic separation: PMS) and novel (phage-bead qPCR: PBQ) phage based assay was optimized. A superior limit of detection (LOD) of 10 MAP per 10 mL milk was suggested for PBQ compared to 100 cells/10 mL for PMS-phage assay. Via PBQ, viable MAP was found in 48.78% out 41 unpasteurized sheep and goat milk samples. Sheep milk samples (n = 29) that were tested by PMS-phage assay contained no viable MAP. The absence of viable MAP in milk collected from 21 of the recent sheep animals was also confirmed by PBQ after a 2-week gap. Although, the two phage assays comparably detected no viable MAP in the milk samples, MAP DNA and antibodies against MAP were recognized in milk and sera of some of these animals within two instances of sampling representing that some sheep animals were MAP shedders. In conclusion, PBQ and PMS-phage could be promising methods for the assessment of MAP viability in milk samples. However, PBQ was privileged over the PMS-phage assay due to the lower LOD, rapidity, higher sensitivity, lack of need to M. smegmatis and consequent virucidal treatment that are essential in PMS-phage assay for making lawn and inactivation of exogenous mycobacteriophages respectively.

Separation of fosetyl and phosphonic acid in food matrices with mixed-mode HPLC column coupled with tandem mass spectrometric detection and method application to other highly polar pesticides.

The aluminum salt of fosetyl (tris(ethyl phosphonate)) is an antifungal agrochemical. This paper presents a novel high performance liquid chromatography (HPLC) method for the simultaneous determination of fosetyl and the phosphonic acid, its main metabolite, in food samples. The method is based on an ion-displacement separation performed on the recently released Luna Omega PS C18 mixed-mode HPLC column. Baseline separation of fosetyl and phosphonic acid was feasible. This was achieved by optimizing the mobile phase composition and by introducing ethylenediaminetetraacetate for all matrices in the generally used extraction medium for polar pesticides and the injection solution. The binary mobile phase consisted of 10% (v/v) methanol in water and aqueous formate buffer (pH = 3.5) in gradient elution mode. The main advantages of the method over previous method include the stable retention time and peak resolution without the need for long column priming, conditioning or regeneration. Moreover, the approach was tested with other polar pesticides including glyphosate, glufosinate, and perchlorate and showed fit-for-purpose separation. The method was validated for spinach, cherry, and wheat flour samples, and was successfully applied on oat flour and arugula quality control samples. The results obtained for the five analytes met the requirements set by EU. The limit of quantifications was much lower than the maximum residue limits and ranged from 0.02 to 0.20 mg/kg.

Recent advances in the analysis of polycyclic aromatic hydrocarbons in food and water.

Polycyclic aromatic hydrocarbons (PAHs), a class of harmful and persistent organic contaminant, are widely distributed in the environment and eventually accumulated in water and food. Also, they are formed in different varieties and varying amounts during processing of food depending on the food composition, cooking method and processing condition. According to the International Agency for Research on Cancer (IARC), various PAHs are classified under Group 1 to 3 category, with Group 1 designated as carcinogenic to humans, Group 2A as probable carcinogen, Group 2B as possible carcinogen and Group 3 as noncarcinogenic. Therefore, it is imperative to develop rapid and highly sensitive analytical methods for determination of PAHs in food and water. This article aims to overview the recent advances of various chromatographic methods as well as electrochemical and SERS-based optical sensing methods for analysis of PAHs in food and water. Initially, several conventional sample preparation methods along with the advanced extraction for isolation of PAHs were summarized, followed by reviewing various gas chromatographic methods coupled with various detection techniques for PAHs analysis in various food products including meat/meat products, seafood, oil, milk/milk products, baby foods, honey, vegetable, cocoa products, tea/coffee, juice, rice, flour, noodle and cake. In addition, high performance liquid chromatographic methods coupled with fluorescence, diode array or mass/tandem mass detection techniques as well as an emerging supercritical fluid chromatographic technique employed for determination of PAHs in different food and water matrices were also overviewed. Finally, various electrochemical sensors and SERS-based optical sensors developed recently for onsite detection of PAHs were tabulated and discussed. Thus, this review article can provide a research update on chromatography and sensor-based analytical methods for PAH analysis as well as enable elucidation of research gaps for future studies.