In-line micro-matrix solid-phase dispersion extraction for simultaneous separation and extraction of Sudan dyes in different spices

CRISPR-Cas-based detection for food safety problems: Current status, challenges, and opportunities

Food safety is one of the biggest public issues occurring around the world. Microbiological, chemical, and physical hazards can lead to food safety issues, which may occur at all stages of the supply chain. In order to tackle food safety issues and safeguard consumer health, rapid, accurate, specific, and field-deployable detection methods meeting diverse requirements are one of the imperative measures for food safety assurance. CRISPR-Cas system, a newly emerging technology, has been successfully repurposed in biosensing and has demonstrated huge potential to establish conceptually novel detection methods with high sensitivity and specificity. This review focuses on CRISPR-Cas-based detection and its current status and huge potential specifically for food safety inspection. We firstly illustrate the pending problems in food safety and summarize the popular detection methods. We then describe the potential applications of CRISPR-Cas-based detection in food safety inspection. Finally, the challenges and futuristic opportunities are proposed and discussed. Generally speaking, the current food safety detection methods are still unsatisfactory in some ways such as being time-consuming, displaying unmet sensitivity and specificity standards, and there is a comparative paucity of multiplexed testing and POCT. Recent studies have shown that CRISPR-Cas-based biosensing is an innovative and fast-expanding technology, which could make up for the shortcomings of the existing methods or even replace them. To sum up, the implementation of CRISPR-Cas and the integration of CRISPR-Cas with other techniques is promising and desirable, which is expected to provide "customized" and "smart" detection methods for food safety inspection in the coming future.

A cartridge-based device for automated analyses of solid matrices by online sample prep-capillary LC-MS/MS

Sample preparation is an essential step focused on eliminating interfering compounds while pre-concentrating the analytes. However, its multiple steps are laborious, time-consuming, and a source of errors. Currently, automated approaches represent a promising alternative to overcome these drawbacks. Similarly, miniaturisation has been considered an ideal strategy for creating greener analytical workflows. The combination of these concepts is currently highly desired by analytical chemists. However, most automated and miniaturised sample preparation techniques are primarily concerned with liquid samples, while solids are frequently overlooked. We present an approach based on a cartridge packed with solids (soil samples) coupled with a capillary LC-MS, combining sample preparation and analytical steps into a unique platform. As a proof-of-concept, nine pesticides used in sugarcane crops were extracted and analysed by our proposed method. For optimisation, a fractional factorial design (2^5-1) was performed with the following variables: aqueous dilution of the sample (V₁), extraction strength (V₂), matrix washing time (V₃), extraction flow (V₄), and analytical flow (V₅). After, the most influential ones (V₁, V₂, and V₃) were taken into a central composite design (2³) to select their best values. Under optimised conditions, the method reported linear ranges between 10 and 125 ng g^-1 with R² > 0.985. Accuracy and precision were in accordance with the values established by the International Council for Harmonisation (Q2(R1)). Therefore, the proposed approach was effective in extracting and analysing selected pesticides in soil samples. Also, we carried out initial qualitative tests for pesticides in honeybees to see if there is the possibility to apply our method in other solids.

Boron nitride nanosheet-assisted matrix solid-phase dispersion microextraction of alkaloids from lotus plumule by high-performance liquid chromatography coupled with ultraviolet detection and ion mobility quadrupole time-of-flight mass spectrometry

A boron nitride nanosheet (BNNS)-assisted matrix solid-phase dispersion method was established to microextract alkaloids from medicinal plants. The target compounds were identified by high-performance liquid chromatography coupled with ultraviolet detection and ion mobility quadrupole time-of-flight mass spectrometry. During the experimental process, several important parameters, including the type of dispersant, the amount of dispersant, the grinding time, and the type of elution solvent, were optimized. Finally, the BNNSs were chosen as the best dispersant, and their microcosmic morphologies were identified by scanning electron microscopy and transmission electron microscopy. Because of the special property of BNNSs, the cost of this experiment was greatly reduced, especially in elution volume, sample amount (50 mg), and extraction time (2 min). Under the best conditions, 50 mg of sample powder was dispersed with 50 mg of BNNSs, the grinding time was 120 s, the mixed powder was eluted with 200 μL of methanol, and good linearity (r²  > 0.9993) and satisfactory recoveries (80-100%) were obtained. The inter- and intraday precisions were acceptable, with RSDs lower than 2.01 and 4.84%, respectively. The limits of detection ranged from 2.54 to 15.00 ng/mL, and the limits of quantitation were 8.47 to 50.00 ng/mL. The proposed method was successfully applied for the determination of liensinine, isoliensinine, and neferine in lotus plumule.

Rapid magnetic enrichment and sensitive detection of Sudan pollutants with nanoscale zero valent iron-based nanomaterials in combination with liquid chromatography-ultraviolet detector

In present work, we reported a new nanomaterial nano Fe⁰ decorated with SiO₂ and dopamine by self-assembly method (Fe@SiO₂@PDA). A sensitive method for determination of Sudan pollutants in aqueous samples was developed using Fe@SiO₂@PDA as magnetic solid phase extraction adsorbents prior to high-performance liquid chromatography with variable wavelength detector. The possible parameters which would affect the enrichment have been optimized. The best parameters were as follows: elutent, 4.5 mL methanol; adsorbent dosage, 30 mg; adsorption time, 20 min; elution time, 18 min; sample pH 7; sample volume, 40 mL. The experimental results demonstrated that Fe@SiO₂@PDA exhibited good adsorption properties to Sudan Red dyes. The established method provided excellent linear ranges over 0.01-50 μg L^-1 and detection limits ranged from 2.0 to 5.1 ng L^-1 for Sudan red I-IV. The developed method was also evaluated with real water samples and the results demonstrated that it was of applicative value owing to its merits including robustness, easy operation, fastness, cheapness and high enrichment efficiency, and had great prospect in environmental fields.

Magnetic and thermal dual-sensitive core-shell nanoparticles for highly preconcentration and measurement of Sudan red pollutants

Recently, thermal-sensitive polymers absorbed much more concerns, and the goal of present work was to modify magnetic nanoparticles with N-isopropylacrylamide (NIPAM) and methyl 3,3-dimethylacrylate (DMMA) for obtaining thermal and magnetic dual-sensitive nanoparticles based on silica coated nanoscale zero valent iron and thermal-sensitive polymers (Fe@p(NIPAM-co-DMMA)). Fe@p(NIPAM-co-DMMA) nanoparticles were fabricated and possessed excellent adsorption ability for Sudan pollutants in aqueous samples. A rapid extraction and separation approach utilizing synthesized dual-sensitive nanomaterials was designed and developed before analysis by liquid chromatography (HPLC). Upon the enrichment factors as their optimal values, the established method gained wonderful linearity over the range of 0.05-500 μg L^-1. The precisions of proposed method were all lower than 3.87%. The validating experiments ensured that this developed method provided with satisfied recoveries in the range of 97.4-102.6% from spiked real water samples, which affirmed that this method was a reliable monitoring tool for Sudan pollutants in water and food samples, etc.

Synthesis of magnetic nanoparticles to detect Sudan dye adulteration in chilli powders

Magnetic nanoparticles were synthesised to extract Sudan dyes from chilli powders. The adsorbents used were magnetic ferroferric oxide nanoparticles coated with polystyrene. The extraction procedures for Sudan dyes comprised liquid-solid extraction and magnetic solid phase extraction. The conditions were optimised to achieve efficient magnetic solid phase extraction, including extraction and desorption time, type and volume of the desorption solvent, and the mass of the adsorbents. Repeatability tests showed satisfactory recovery rates of 80.2-115.8%, with a relative standard deviation <3.8%. The results suggested that the proposed extraction method was effective and efficient to extract Sudan dyes from chilli powders. The extraction process was simpler compared with traditional approaches because the adsorbents can be rapidly removed from the sample matrix using a permanent magnet. The use of recyclable adsorbents decreased the cost greatly. Chilli powder samples collected from local markets in Singapore were tested using the proposed method under optimum conditions.

A Review on the Recent Progress in Matrix Solid Phase Dispersion

Matrix solid phase dispersion (MSPD) has proven to be an efficient sample preparation method for solid, semi-solid, and viscous samples. Applications of MSPD have covered biological, food, and environmental samples, including both organic and inorganic analytes. This review presents an update on the development of MSPD in the period 2015~June 2018. In the first part of this review, we focus on the latest development in MSPD sorbent, including molecularly imprinted polymers, and carbon-based nanomaterials etc. The second part presents the miniaturization of MSPD, discussing the progress in both micro-MSPD and mini-MSPD. The on-line/in-line techniques for improving the automation and sample throughput are also discussed. The final part summarizes the success in the modification of original MSPD procedures.

Analysis of unauthorized Sudan dyes in food by high-performance thin-layer chromatography

Food authenticity and food safety are of high importance to organizations as well as to the food industry to ensure an accurate labeling of food products. Respective analytical methods should provide a fast screening and a reliable cost-efficient quantitation. HPTLC was pointed out as key analytical technique in this field. A new HPTLC method applying caffeine-impregnated silica gel plates was developed for eight most frequently found fat-soluble azo dyes unauthorizedly added to spices, spice mixtures, pastes, sauces, and palm oils. A simple post-chromatographic UV irradiation provided an effective sample cleanup, which took 4 min for up to 46 samples in parallel. The method was trimmed to enable 23 simultaneous separations within 20 min for quantitation or 46 separations within 5 min for screening. Linear (4-40 ng/band) or polynomial (10-200 ng/band) calibrations of the eight azo dyes revealed high correlation coefficients and low standard deviations. Limits of detection and quantification were determined to be 2-3 and 6-9 ng/zone, respectively. After an easy sample extraction, recoveries of 70-120% were obtained from chili, paprika, and curcuma powder as well as from chili sauce, curry paste, and palm oil spiked at low (mainly 25-50 mg/kg) and high levels (150-300 mg/kg). For unequivocal identification, the compound in a suspect zone was eluted via a column into the mass spectrometer. This resulted in the hyphenation HPTLC-vis-HPLC-DAD-ESI-MS. Graphical abstract Simplified clean-up by UV irradiation for Sudan dye analysis in food by HPTLC-vis-HPLC-DAD-ESI-MS.

Spatial Profiling of Gibberellins in a Single Leaf Based on Microscale Matrix Solid-Phase Dispersion and Precolumn Derivatization Coupled with Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry

A spatial-resolved analysis method for profiling of gibberellins (GAs) in a single leaf was developed on the basis of microscale sample preparation and precolumn derivatization coupled with ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The proposed microscale sample preparation was based on modified matrix solid-phase dispersion (MSPD) method, in which the plant sample (<1 mg) and C18 sorbent were ground together in one microcentrifuge tube, and then extraction solvent was added followed by centrifugation. In this protocol, the grinding, extraction, and purification were performed in one microcentrifuge tube without any sample transfer step, resulting in an obvious decrease in sample loss. Moreover, a new derivatization reagent, 3-bromopropyltrimethylammonium bromide (BPTAB), was used to further enhance the signal intensities of GAs on MS by 3-4 orders of magnitude, which was much higher than the reported derivatization reagents for GAs such as bromocholine bromide and 3-bromoactonyltrimethylammonium bromide. The present method showed high sensitivity (minimum detectable amount (MDA) of 10.1-72.3 amol for eight GAs) and low sample consumption (down to 0.30 mg FW). Under the optimized conditions, the distribution of GA₁₉ in a single Arabidopsis thaliana leaf was profiled with a spatial resolution of 2 × 2 mm².