Development and Application of a Novel Multiloop Splitter-Based Non-cryogenic Artificial Trapping Modulation System in Comprehensive Two-Dimensional Gas Chromatography.

A multiloop splitter-based non-cryogenic artificial trapping (M-SNAT) modulation technique was established, which applied the first (1D) nonpolar and the second (2D) polar columns, deactivated fused silica (DFS) columns, a microfluidic Deans switch (DS), and splitters located between the 1D column outlet and the DS. The splitters were connected into multiple loops with a progressively doubled perimeter of the next loop. This enabled a duplex splitting mechanism within each loop consisting of splitting of analyte pulses, the pulse delay, and their combination which led to equally split peaks of the same analytes with the number of split peaks (nsplit) equal to 2m (m = number of loops). This system resulted in local profiles of artificially split-and-trapped analytes prior to their selective transfers onto the 2D column by means of periodic multiple heart-cuts (H/C). The developed SNAT approach can be successful, providing that the ratio of modulation period to sampling time (PM/tsamp) is equal to nsplit. The approach with nsplit = 16 was further developed into a single device platform and applied for the modulation of a wide range of compounds in waste tire pyrolysis samples with the RSD of ≤0.01 and <10% for the one-dimensional modulated peak times and peak areas, respectively (n = 50). The method enabled an artificial modulation mechanism without cryogen consumption and enhanced the 2D peak capacity (2nc) and 2D separation by use of a longer 2D column.

Recent Developments and Applications of Microfluidic Paper-Based Analytical Devices for the Detection of Biological and Chemical Hazards in Foods: A Critical Review.

Nowadays, food safety has become a major concern for the sustainability of global public health. Through the production and distribution steps, food can be contaminated by either chemical hazards or pathogens, and the determination of these plays a critical role in the processes of ensuring food safety. Therefore, the development of analytical tools that can provide rapid screening of these hazards is highly necessary. Microfluidic paper-based analytical devices (µPADs) have advanced significantly in recent years as they are rapid and low-cost analytical screening tools for testing contaminated food products. This review focuses on recent developments of µPADs for various applications in the food safety field. A description of the fabrication of selected papers is briefly discussed, and evaluation of the µPADs' performance with regard to their precision and accuracy as well as their limits of detection is critically assessed. The advantages and disadvantages of these devices are highlighted.

Gel electromembrane microextraction followed by ion chromatography for direct determination of iodine in supplements and fortified food samples: Green chemistry for food analysis.

In this study, a sensitive, selective, and environmentally friendly analytical method for direct extraction and preconcentration of iodine was developed. Iodine, as an iodate ion or iodide ion, was simultaneously extracted and preconcentrated by gel electromembrane microextraction (G-EME) and analyzed for total iodine by ion chromatography. The total iodine was determined by combining the peak areas of both iodate and iodide ions. Under the optimized conditions, linear calibration for iodine using a mixture of iodate and iodide ions was obtained from 10 to 100 µg L-1 (r2 > 0.996). The detection limit was 7.0 µg L-1. Recoveries of spiked iodine (as iodate) in the samples were greater than 90%. The method was applied for the determination of iodine in dietary supplements and fortified food samples, i.e., iodine-enriched eggs. Our developed method could be directly applied for the determination of iodine in different matrix samples including eggs without a pretreatment step.

Simultaneous determination of benzoic acid, sorbic acid, and propionic acid in fermented food by headspace solid-phase microextraction followed by GC-FID.

A simple and environmentally friendly method was developed for simultaneous determination of benzoic acid, sorbic acid, and propionic acid in fermented food samples. The analytes were extracted and pre-concentrated by headspace solid-phase microextraction (HS-SPME) and analysed by GC-FID. Central composite design (CCD) was conducted for the optimization of HS-SPME conditions. Under optimal conditions, a good linear range was obtained in the range of 5-150 mg L-1. The limit of detection (LOD) values were 1.1-1.7 mg L-1. The developed method was successfully applied to determine the concentration of three organic acid preservatives in various fermented food samples, including thai shrimp paste, pickled vegetables, soy sauce and fish sauce, with high accuracy (recoveries were between 83% and 109%) and good precision (%RSD was less than 6.0% and 4.5% for intra-day and inter-day, respectively).

Poly(cyclodextrin-ionic liquid) based ferrofluid: A new class of magnetic colloid for dispersive liquid phase microextraction of polycyclic aromatic hydrocarbons from food samples prior to GC-FID analysis.

Poly(ß-cyclodextrin-ionic liquid) grafted magnetic nanoparticles combined with 1-octanol as supramolecular solvents (SUPRASs) presenting new ferrofluid was developed and successfully applied in the dispersive liquid-phase microextraction of seven representative polycyclic aromatic hydrocarbons. One variable at-a-time (OVAT) analysis and response surface methodology (RSM) were used for efficient optimization of the main variables. The calibration curves were found to be linear in the range of 0.1-150 ng mL-1 with correlation of determinations (R2) ranging from 0.9944 to 0.9986. Detection limits ranged at 0.02-0.07 ng mL-1 for all studied PAHs. The intra and inter-day precision values (RSD %) were in the range of 1.80%-7.56% and 2.97%-8.23%, respectively. The ferrofluid showed a satisfactory reproducibility between 1.72% and 5.90%, and acceptable recovery values at 84%-110% were obtained for the real samples analysis. The optimized method was successfully applied to access the content safety of the PAHs studied in a variety of commercial food and beverages available in Malaysia.

Chromium speciation using paper-based analytical devices by direct determination and with electromembrane microextraction.

In this study, we developed and compared three different methods for chromium speciation in water samples using microfluidic paper-based analytical devices (µPADs). In all methods, detection was based on the complexation reaction of Cr(VI) with diphenylcarbazide on the µPADs. Cr(III) ions were oxidized to Cr(VI) by Ce(IV) prior to colorimetric detection on the µPADs. In the first method, oxidization of Cr(III) to Cr(VI) in the solution containing both trivalent and hexavalent chromium was performed using a batch procedure to obtain total chromium. A dual electromembrane extraction (DEME) technique for simultaneous preconcentration and extraction of chromium species and a single electromembrane extraction (SEME) for preconcentration and extraction of Cr(VI)/total chromium [quantified as Cr(VI) content after oxidation of Cr(III) ions to Cr(VI)] were used in the second and third methods, respectively. The electromembrane extraction was based on the electrokinetic migration of cationic Cr(III) and anionic Cr(VI) toward the cathode and anode, respectively, into the two different hollow fibres. Octanol-1 and bis(2-ethylhexyl) phosphate (DEHP) in octanol-1 (0.7% v/v) were the most suitable supported liquid membranes for extraction of Cr(VI) and Cr(III), respectively. Among these methods, SEME showed the lowest limits of detection for both analytes. Under optimized conditions, linear calibrations were obtained for Cr(III) from 3 to 30 µg L-1 and for Cr(VI) from 3 to 70 µg L-1. The detection limits were 1.0 µg L-1 and 0.7 µg L-1 for Cr(III) and Cr(VI), respectively. Our developed method was applied to analyse water samples spiked with different concentrations of Cr(III) and Cr(VI) at the parts-per-billion (ppb) level. The statistical evaluation showed that the proposed method agreed well with the validation method, i.e., inductively coupled plasma atomic emission spectroscopy (ICP-AES).

Low-temperature cleanup with solid-phase extraction for the determination of polycyclic aromatic hydrocarbons in edible oils by reversed phase liquid chromatography with fluorescence detection.

Low-temperature cleanup, which is a simple and cost-efficient sample preparation technique that allows the convenient treatment of multiple samples simultaneously, was developed in conjunction with solid-phase extraction (SPE) cleanup for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in refined and used edible oil samples by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Samples are extracted with a small amount of organic solvent and most of lipids in the extract were removed by low-temperature cleanup. SPE cartridge was used to further cleanup prior to HPLC-FLD analysis. Optimum extraction of low-temperature cleanup was achieved when using two extractions with a 4:1 (v/v) mixture of acetonitrile: acetone as the extraction solvent, freezing at between -18 °C and -25 °C for 24 h and then cleanup with an Alumina-N SPE cartridge. The PAH recoveries were 45.9-118.5%, with limit of detection (LOD) and limit of quantitation (LOQ) values of 0.13-3.13 µg/kg and 0.25-6.25 µg/kg across the 16 tested PAHs, respectively. The validated method was successfully applied for the determination of PAHs in reference materials of olive oil and real refined and used edible oil samples.