Ultrasonic-assisted extraction and dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry as an efficient and sensitive method for determining of acrylamide in potato chips samples

Trioctylphosphine oxide-based hydrophobic magnetic deep eutectic solvent as a novel extractant for the enrichment of primary aromatic amines from juice and environmental water

In this study, a novel technique utilizing vortex-assisted dispersive liquid-liquid microextraction with magnetic deep eutectic solvents (MDESs) was established and coupled with HPLC-UV to analyze six primary aromatic amines (PAAs). A novel hydrophobic MDES prepared from trioctylphosphine oxide, octanol, and CoCl2 was used as the extractant, which could be dispersed uniformly during extraction, then floated onto the sample surface and re-aggregated into a single drop spontaneously after the extraction. The variables influencing the efficiency of the extraction process were investigated. When performing under the optimal extraction conditions, this method exhibited excellent linearity, low limits of detection (0.2-0.9 ng mL-1), and high precision (RSD ≤ 8.3 %). The enrichment factors ranged from 56 to 182. Satisfactory recoveries in the range of 91.6-109.2 % with RSDs < 7.1 % were obtained from three apple juices and three environmental water samples. The greenness and practicality of the developed method were assessed by AGREE, AGREEprep, and blue applicability grade index metric tools. Overall, the established procedure demonstrated its simplicity, speediness, environmental friendliness, and effectiveness in analyzing PAAs from aqueous matrices.

In-situ growth of metal-organic frameworks on cellulose nanofiber aerogels for rapid adsorption of heterocyclic aromatic amines

Heterocyclic aromatic amines (HAAs) are the main carcinogens produced during thermal processing of protein-rich foods. In this paper, a composite aerogel (TOCNFCa) with a stabilized dual-network structure was prepared via a template for the in-situ synthesis of UiO-66 on cellulose for the adsorption of HAAs in food. The dual-network structure of TOCNFCa provides the composite aerogel with excellent wet strength, maintaining excellent compressive properties. With the in-situ grown UiO-66 content up to 71.89 wt%, the hierarchical porosity endowed TOCNFCa@UiO-66 with the ability to rapidly adsorb HAAs molecules with high capacity (1.44-5.82 μmol/g). Based on excellent thermal stability, adsorption capacity and anti-interference, TOCNFCa@UiO-66 achieved satisfactory recoveries of HAAs in the boiled marinade, which is faster and more economical than the conventional SPE method. Moreover, TOCNFCa@UiO-66 could maintain 84.55 % of the initial adsorption capacity after 5 times of reuse.

Thiol-ene click derivatization reaction coupled with ratiometric surface-enhanced Raman scattering for reproducible and accurate determination of acrylamide

Acrylamide (AA) is a carcinogen mainly ingested through food and drinking water, making its accurate determination crucial for both food safety and environmental protection. Herein, we proposed a derivatization-based ratiometric surface-enhanced Raman scattering (SERS) method for the quantification of AA. High density Au NPs were anchored to the surface of Cu-TCPP MOF nanosheets (MOFNs) to form the SERS sensor. The abundant Raman "hot spots" at the nanogaps generated by the Au NPs and the internal standard (IS) signal provided by Cu-TCPP MOFNs improved the sensitivity and quantitative accuracy of the method. Following the thiol-ene click derivatization reaction between p-aminothiophenol (PATP) and AA, the Raman peak intensity ratio (I1080/I395) was employed to quantify AA. The linear range was 0.1 nM to 10 μM, and the limit of detection (LOD) was as low as 0.08 nM. Trace amounts of AA in food and water samples were successfully determined using this method.

Toxicity, formation, contamination, determination and mitigation of acrylamide in thermally processed plant-based foods and herbal medicines: A review

Thermal processing is one of the important techniques for most of the plant-based food and herb medicines before consumption and application in order to meet the specific requirement. The plant and herbs are rich in amino acids and reducing sugars, and thermal processing may lead to Maillard reaction, resulting as a high risk of acrylamide pollution. Acrylamide, an organic pollutant that can be absorbed by the body through the respiratory tract, digestive tract, skin and mucous membranes, has potential carcinogenicity, neurological, genetic, reproductive and developmental toxicity. Therefore, it is significant to conduct pollution determination and risk assessment for quality assurance and security of medication. This review demonstrates state-of-the-art research of acrylamide focusing on the toxicity, formation, contamination, determination, and mitigation in taking food and herb medicine, to provide reference for scientific processing and ensure the security of consumers.

Trace determination of prohibited acrylamide in cosmetic products by vortex-assisted reversed-phase dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry

An analytical method for the determination of residual acrylamide in cosmetic products containing potential acrylamide-releasing ingredients is presented. The method is based on vortex-assisted reversed-phase dispersive liquid-liquid microextraction (VA-RP-DLLME) to extract and preconcentrate acrylamide by using water as extraction solvent taking advantage the highly polar behavior of this analyte, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for its determination. Under optimized conditions (5 mL toluene as supporting solvent, 50 µL of water as extraction solvent, 1 min for vortex extraction time) the method was properly validated obtaining good analytical features (linearity up to 20 ng mL^-1, method limits of detection and quantification of 0.51 and 1.69 ng g^-1, respectively, enrichment factor of 52, and good repeatability (RSD < 4.1%)). The proposed analytical method was applied to the determination of acrylamide in commercial samples that were weighed and dispersed in the minimum quantity of methanol (50 µL) by vortex stirring before applying the VA-RP-DLLME procedure. Through the pretreatment of the sample and the use of acrylamide-d₃ as surrogate, the matrix effect was overcome, obtaining good relative recovery values (88-108%). The proposed method has shown efficacy, simplicity, and speed, and it allows the determination of acrylamide at trace levels easily, which could make it very useful for companies in the quality control of cosmetic products containing potential acrylamide-releasing ingredients to fulfill the safety limits imposed by European Regulation.

SiO2 Microsphere Array Coated by Ag Nanoparticles as Raman Enhancement Sensor with High Sensitivity and High Stability

In this paper, a monolayer SiO₂ microsphere (MS) array was self-assembled on a silicon substrate, and monolayer dense silver nanoparticles (AgNPs) with different particle sizes were transferred onto the single-layer SiO₂ MS array using a liquid–liquid interface method. A double monolayer “Ag@SiO₂” with high sensitivity and high uniformity was prepared as a surface-enhanced Raman scattering (SERS) substrate. The electromagnetic distribution on the Ag@SiO₂ substrate was analyzed using the Lumerical FDTD (finite difference time domain) Solutions software and the corresponding theoretical enhancement factors were calculated. The experimental results show that a Ag@SiO₂ sample with a AgNPs diameter of 30 nm has the maximal electric field value at the AgNPs gap. The limit of detection (LOD) is 10⁻¹⁶ mol/L for Rhodamine 6G (R6G) analytes and the analytical enhancement factor (AEF) can reach ~2.3 × 10¹³. Our sample also shows high uniformity, with the calculated relative standard deviation (RSD) of ~5.78%.

New and efficient magnetic nanocomposite extraction using multifunctional deep eutectic solvent based on ferrofluid and vortex assisted-liquid-liquid microextraction: Determining primary aromatic amines (PAAs) in tetra-packed fruit juices

In this work, a novel magnetic nanocomposite solvent (MNCS) based on ferrofluid and multifunctional deep eutectic solvent (MDES) was synthesized and applied in vortex assisted-liquid-liquid microextraction (VA-LLME). The ferrofluid has been composed from zirconium phosphate (modified magnetic graphene oxide) and tetrabutylammonium bromide-octanoic acid deep eutectic solvent (MGO/α-ZrP@TBAB-OA). This efficient method was employed to determine primary aromatic amines including aniline, 4-methoxyanniline, 4,4'-diaminodiphenylmethane, orthotoluidine, 2,6-dimethylaniline, 2-naphtylamine in tetra-packed juice samples. The proposed method showed the excellent extraction efficiency of PAAs according to strong interactions of new extraction solvent including electrostatic, π-π, and hydrogen bonding attractions. The found levels of PAAs are lower than the limit of quantifications (2.0 µg L^-1). Therefore, the migration of PAAs from packaging to the juice samples is lower than permitted level (<10 µg kg^-1). The results indicated high potential use of the offered method to analyze aromatic amine compounds in foodstuff and biologic samples in the future.

Investigation on the interaction of acrylamide with soy protein isolate: Exploring the binding mechanism in vitro

Acrylamide (AA), which is a carcinogen in humans, has been a research focus in terms of food risk assessment. However, few published studies have explored protein strategies to reduce the health risks of AA. The objective of this study was to investigate the binding of AA with soy protein isolate (SPI) and elucidate the binding mechanism. The results showed that AA could bind with nontreated, heat-treated, high-pressure homogenization-treated, and ultrasound-treated SPI in vitro. Fourier-transform infrared spectroscopy suggested that secondary structure of SPI changed significantly after binding with AA in the nontreated and different treated groups. Moreover, fluorescence quenching experiments suggested that the quenching of SPI by AA was static quenching and hydrogen bonds, hydrophobic interactions, and van der Waals forces were involved in this process. PRACTICAL APPLICATION: The study of SPI and AA binding could provide a new perspective for reducing the bioaccessibility of AA in human body by using protein. The results showed that SPI could potentially be used as a novel health strategy to reduce the harm of AA in the human body.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Strawberry-like SiO2/Ag nanocomposites immersed filter paper as SERS substrate for acrylamide detection

In this work, based on the strawberry-like SiO₂/Ag nanocomposites (SANC) immersed filter paper, a newly surface-enhanced Raman scattering (SERS) substrate was constructed for the detection of acrylamide (AAm) in food products. To construct filter paper-based SANC (F-SANC) SERS substrates, SiO₂ nanoparticles (SNP) were firstly synthesized and acted as carriers. After that, the in-situ preparation of silver nanoparticles (Ag NP) on SNP surface was carried out to form the strawberry-like three-dimensional (3D) structure of SANC. Finally, SANC were entangled into the filter paper to produce nanoarchitecture, thus providing enhanced plasmon resonance between SANC with strong SERS signal. Under the optimized conditions, the method exhibited good performance toward AAm with a vast linear response from 0.1 nM to 50 μM (R = 0.9935), limit of detection (LOD) of 0.02 nM (S/N = 3), and the recoveries of 80.5%~105.6% for practical samples. This strategy showed good robustness in the rapid and sensitive detection of AAm, which could be a promising strategy in food analysis and verification.

Reduction in Acrylamide Formation in Potato Crisps: Application of Extract and Hydrocolloid-Based Coatings

ABSTRACT

Two different potato chip coatings-aqueous extracts including Zataria multiflora and Allium hirtifolium at concentrations of 1, 3, 5, and 7% and hydrocolloids individually or in combination-were used to decrease acrylamide content, and their effects on the characteristics of the product were then investigated. According to the results, the incorporation of hydrocolloids as the coating was more efficient in the reduction of acrylamide production than with the extracts. Also, the application of each extract and hydrocolloids individually can be considered a more efficient technique for acrylamide reduction than their mixture. In this regard, the economic aspects of the application of hydrocolloids in the coating of fried potato crisps can be evaluated.

HIGHLIGHTS

Review of Research into the Determination of Acrylamide in Foods

Acrylamide (AA) is produced by high-temperature processing of high carbohydrate foods, such as frying and baking, and has been proved to be carcinogenic. Because of its potential carcinogenicity, it is very important to detect the content of AA in foods. In this paper, the conventional instrumental analysis methods of AA in food and the new rapid immunoassay and sensor detection are reviewed, and the advantages and disadvantages of various analysis technologies are compared, in order to provide new ideas for the development of more efficient and practical analysis methods and detection equipment.

Combination of solid-phase extraction with microextraction techniques followed by HPLC for simultaneous determination of 2-methylimidazole and 4-methylimidazole in beverages

A sensitive analytical method for the monitoring 2-methylimidazole and 4-methylimidazole (2-MI and 4-MI) is desirable due to their carcinogenic property. Here, we propose a highly sensitive method basing on the combination of solid-phase extraction and dispersive liquid-liquid microextraction techniques followed by high-performance liquid chromatography to simultaneously determine 2-MI and 4-MI in beverages. Dansyl chloride was used as a derivatizing reagent. Microextraction parameters were optimized by Plackett-Burman design and response surface methodology. Results show that derivatization led to significant improvements in chromatographic behavior for 2-MI and 4-MI due to increased hydrophobicity. The method shows good linearity (R² ≥ 0.9985), satisfactory precision (%RSD ≤ 8.3%) and low limit of quantification (20 ng/mL), and was successfully applied to determine 2-MI and 4-MI in carbonated drinks, beers and energy drinks, achieving satisfactory recoveries (85-101%). This method provides a potential for routine analysis of 2-MI and 4-MI at the nanogram per milliliter level in beverages.

High-Performance Liquid Chromatography Determination of Acrylamide after Its Extraction from Potato Chips

Background: Acrylamide is a known carcinogenic product that has been found among the substances such as potato chips which to be processed under the heat-treatment. In order to extract amounts of acrylamide from fried chips in market, an ultrasound-assisted liquid– liquid extraction (UA-LLE) technique is proposed. The UA-LLE coupled LLE and ultrasonication in a single step. Methods: Chips samples were dissolved in an extracting organic solvent using ultrasonication to prompt transferring of acrylamide into the organic phase. As a result, the extraction time and process efficiency were significantly enhanced through increasing the collision power and mass transfer between grounded chips and organic phase. Results: Important parameters affecting the extraction efficiency such as kind of organic solvent and its volume, re-dissolving solvent and pH were optimized. This newly proposed method has been applied to determine the trace acrylamide in potato chips samples purchased from local market. Conclusion: UA-LLE is a handy, economic and time-saving method, with high extraction yield (over 103% average recovery) and good precision (lower than 15% relative standard deviation, RSD). Most importantly, it seems this method to be an ideal pre-treatment method for the extraction of acrylamide in food matrix in food quality control laboratories.

Determination of Acrylamide in Biscuits by High-Resolution Orbitrap Mass Spectrometry: A Novel Application

Acrylamide (AA), a molecule which potentially increases the risk of developing cancer, is easily formed in food rich in carbohydrates, such as biscuits, wafers, and breakfast cereals, at temperatures above 120 °C. Thus, the need to detect and quantify the AA content in processed foodstuffs is eminent, in order to delineate the limits and mitigation strategies. This work reports the development and validation of a high-resolution mass spectrometry-based methodology for identification and quantification of AA in specific food matrices of biscuits, by using LC-MS with electrospray ionization and Orbitrap as the mass analyser. The developed analytical method showed good repeatability (RSDr 11.1%) and 3.55 and 11.8 μg kg-1 as limit of detection (LOD) and limit of quantification (LOQ), respectively. The choice of multiplexed targeted-SIM mode (t-SIM) for AA and AA-d3 isolated ions provided enhanced detection sensitivity, as demonstrated in this work. Statistical processing of data was performed in order to compare the AA levels with several production parameters, such as time/cooking temperature, placement on the cooking conveyor belt, color, and moisture for different biscuits. The composition of the raw materials was statistically the most correlated factor with the AA content when all samples are considered. The statistical treatment presented herein enables an important prediction of factors influencing AA formation in biscuits contributing to putting in place effective mitigation strategies.

Thiol-ene Click Derivatization for the Determination of Acrylamide in Potato Products by Capillary Electrophoresis with Capacitively Coupled Contactless Conductivity Detection

The development of analytical methods for acrylamide formed during food processing is of great significance for food safety, but limited by its inherent characteristics, the analysis of acrylamide is a continuing challenge. In this study, an efficient derivatization strategy for acrylamide based on thiol-ene click reaction with cysteine as derivatization reagent was proposed, and the resulting derivative was then analyzed by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D). After systematic investigation including catalyst dosage (0-20 mM), reaction temperature (30-90 °C) and time (1-60 min), and cysteine concentration (0.2-3.6 mM), acrylamide could be efficiently labeled by 2.0 mM cysteine at 70 °C for 10 min using 4 mM n-butylamine as catalyst. Application of 10 mM triethylamine as separation buffer, the labeled acrylamide was analyzed within 2.0 min, and the relative standard deviations of migration time and peak area were less than 0.84% and 5.6%, indicating good precision. The C⁴D signal of acrylamide derivative showed a good linear relationship with acrylamide concentration in the range of 7-200 μM with the correlation coefficient of 0.9991. The limit of detection and limit of quantification were calculated to be 0.16 μM and 0.52 μM, respectively. Assisted further by the QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample pretreatment, the developed derivatization strategy and subsequent CE-C⁴D method were successfully applied for the determination of acrylamide in potato products.

A highly sensitive determination method for acrylamide in beverages, grains, and confectioneries by supercritical fluid chromatography tandem mass spectrometry

Acrylamide (AA) analysis is an important topic in food safety. However, it is difficult to rapidly and accurately analyze low concentrations of AA with currently available methods. In the present study, we introduce a highly sensitive method that enables the determination of AA in beverages, grains, and confectioneries by supercritical fluid chromatography tandem mass spectrometry (SFC/MS/MS). The sensitivity of the SFC/MS/MS technique is 11-times higher than that obtained by ultra-high performance liquid chromatography tandem mass spectrometry. We demonstrated that the highly sensitive SFC/MS/MS method was able to quantify low concentrations of AA in beverages (i.e., roasted barley tea and coffee) extracts at less than 10 µg kg^-1 level without solid-phase purification. Furthermore, the simplification of the sample preparation procedure provided an improvement in data acquisition time (60 samples per 12 h). In conclusion, the developed analytical system is a potentially useful tool for practical AA determination.

Simultaneous Determination of Acrylamide and 5-Hydroxymethylfurfural in Heat-Processed Foods Employing Enhanced Matrix Removal-Lipid as a New Dispersive Solid-Phase Extraction Sorbent Followed by Liquid Chromatography-Tandem Mass Spectrometry

The goal of this study was to develop a method for simultaneous determination of acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) in heat-processed foods by liquid chromatography-tandem mass spectrometry analysis. Several cleanup methods for the quick, easy, cheap, effective, rugged, and safe (QuEChERS) protocol were investigated and compared: (a) dispersive solid-phase extraction (d-SPE) with Enhanced Matrix Removal-Lipid (EMR-Lipid), (b) d-SPE with primary secondary amine, (c) without the cleanup step, and (d) cleanup with n-hexane. It is the first time that EMR-Lipid sorbent has been used as a d-SPE material to detect AA and 5-HMF in heat-processed foods, and among the four cleanup methods, the EMR-Lipid method provided the best cleanup of co-extracted matrix interferences and the highest extraction efficiency. Validation experiments were carried out for the method using EMR-Lipid as the d-SPE sorbent. Excellent linearity ( R² > 0.999) was achieved, and the limits of detection (LODs) of AA and 5-HMF were 2.5 and 12.5 μg/kg, respectively. The recoveries of AA and 5-HMF levels obtained were in the ranges of 87.3-103.3 and 83.2-104.3%, with precision [relative standard deviations (RSDs)] of 1.2-6.8 and 1.4-7.4% ( n = 3), respectively. The method is accurate and reliable and was successfully applied to analyze the AA and 5-HMF in eight categories of Chinese heat-processed foods.

Extending the scope of dispersive liquid-liquid microextraction for trace analysis of 3-methyl-1,2,3-butanetricarboxylic acid in atmospheric aerosols leading to the discovery of iron(III) complexes

3-Methyl-1,2,3-butanetricarboxylic acid (MBTCA) is a secondary organic aerosol and can be used as a unique emission marker of biogenic emissions of monoterpenes. Seasonal variations and differences in vegetation cover around the world may lead to low atmospheric MBTCA concentrations, in many cases too low to be measured. Hence, an important tool to quantify the contribution of terrestrial vegetation to the loading of secondary organic aerosol may be compromised. To meet this challenge, a dispersive liquid–liquid microextraction (DLLME) method, known for the extraction of hydrophobic compounds, was extended to the extraction of polar organic compounds like MBTCA without compromising the efficiency of the method. The extraction solvent was fine-tuned using tri-n-octyl phosphine oxide as additive. A multivariate experimental design was applied for deeper understanding of significant variables and interactions between them. The optimum extraction conditions included 1-octanol with 15% tri-n-octyl phosphine oxide (w/w) as extraction solvent, methanol as dispersive solvent, 25% NaCl dissolved in 5 mL sample (w/w) acidified to pH 2 using HNO₃, and extraction time of 15 min. A limit of detection of 0.12 pg/m³ in air was achieved. Furthermore, unique complexation behavior of MBTCA with iron(III) was found when analyzed with ultra-high-performance liquid chromatography coupled with electrospray ionization–quadrupole time-of-flight mass spectrometry (UHPLC–ESI–QToF). A comprehensive overview of this complexation behavior of MBTCA was examined with systematically designed experiments. This newly discovered behavior of MBTCA will be of interest for further research on organometallic photooxidation chemistry of atmospheric aerosols.

Graphical abstract

Modified QuEChERS purification and Fe3O4 nanoparticle decoloration for robust analysis of 14 heterocyclic aromatic amines and acrylamide in coffee products using UHPLC-MS/MS

Based on QuEChERS dispersed purification, Fe₃O₄ nanoparticle decoloration and UHPLC-MS/MS, a robust and sensitive method was established for simultaneous analysis of 14 heterocyclic aromatic amines (HAAs) and acrylamide (AA) in coffee products. Sample was extracted by 90% acetonitrile water (v/v), dispersed with primary secondary amine (PSA) and further purified with Fe₃O₄ nanoparticle. Then, 15 analytes were detected using ESI positive ion under MRM mode. Good linearity was observed for all analytes in the range of 0.2-100 μg/L with the determination coefficients being above 0.996. Limits of detection (S/N ≥ 3) and limits of quantification (S/N ≥ 10) were in the range of 0.02-0.15 µg/L and 0.2-0.7 µg/L, respectively. The intra-day average recoveries were between 81.6% and 100%, and the intra-day precisions ranged from 4.3% to 9.0%. The inter-day average recoveries were in the range of 81.0-101% with precisions ranging from 5.0% to 7.8%. Results indicated that the combination of PSA and Fe₃O₄ exhibited superior purification and adsorption effects for removing pigments and acid compounds. Real samples analysis indicated that coffee products were widely contaminated with AA, harman and norharman.

2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L^-1 with a determination coefficient (R²) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L^-1, respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L^-1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%).