A large scale study of portable sweat test sensor for accurate, non-invasive and rapid COVID-19 screening based on volatile compound marker detection.

This study established a novel infield sensing approach based on detection of the volatile compound markers in skin secretions. This was based on analysis of volatile compounds in axillary sweat samples collected from RT-PCR-proven Coronavirus disease 2019 (COVID-19) positive and negative populations using gas chromatography-mass spectrometry (GC-MS). The analysis proposed the possible markers of the monoaromatic compounds and ethyl hexyl acrylate.

Modulation of the gut microbiota and short-chain fatty acid production by gac fruit juice and its fermentation in colonic fermentation.

This study aimed to investigate the effects of gac fruit juice and its probiotic fermentation (FGJ) utilizing on the modulation of the gut microbiota and the production of short-chain fatty acids (SCFAs). We conducted a comparison between FGJ, non-fermented gac juice (GJ), and control samples through digestion and colonic fermentation using the human gut microbiota derived from fecal inoculum. Our findings revealed that both GJ and FGJ led to an increase in the viability of , with FGJ exhibiting even higher levels compared to the control.

Gas chromatography-flame ionization detector for sweat based COVID-19 screening.

Simple approach for rapid screening of corona virus disease 2019 (COVID-19) has been developed. This applied gas chromatography-flame ionization detector (GC-FID) analyzing the potential compound marker in sweat samples obtained from COVID-19 positive and negative volunteers in Bangkok, Thailand. The samples were collected by using cotton rods for 15 min, heated at 90 °C for 5 min, and the volatile compounds in the headspace (HS) were injected (5.

Development of a new paper-based voltage step electrocoagulation technique and application to wine classification.

This study developed a novel voltage step electrocoagulation (VSEC) technique on paper for analysis and classification of red wine samples. The concept relies on the electrode system applying voltage steps along a strip of filter paper soaked with a wine sample. The system employed a cathode array system (CAS) for voltage step application and an aluminium anode undergoing corrosion to form the green sludges responsible for wine color bleaching along the paper.

Miniaturized electrocoagulation approach for removal of polymeric pigments and selective analysis of non- and mono-hydroxylated phenolic acids in wine with HPLC-UV.

Electrocoagulation (EC) approach was developed to allow fast sample cleanup step prior to selective analysis of non- and mono-hydroxylated phenolic acids in red wine samples with high performance liquid chromatography hyphenated with UV detection (HPLC-UV). EC system with the wine in KCl electrolyte (1.5 mol L) was employed removing the polymeric pigments with good recovery of 39 peaks from 64 peaks.

Thin layer chromatography based extraction approaches for improved analysis of volatile compounds with gas chromatography-mass spectrometry and direct analysis with gas analyzer.

In this study, thin-layer chromatography was applied for selective extraction of volatile compounds in perfume prior to analysis with solid phase microextraction and gas chromatography-mass spectrometry. The standard compounds were desorbed from the thin-layer chromatography plate and extracted at 80°C for 15 min showing good linearity of the calibration curves (R > 0.98) and acceptable recovery range (65-81%).

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.

Identification of Volatile Compounds and Selection of Discriminant Markers for Elephant Dung Coffee Using Static Headspace Gas Chromatography-Mass Spectrometry and Chemometrics.

Elephant dung coffee (Black Ivory Coffee) is a unique Thai coffee produced from Arabica coffee cherries consumed by Asian elephants and collected from their feces. In this work, elephant dung coffee and controls were analyzed using static headspace gas chromatography hyphenated with mass spectrometry (SHS GC-MS), and chemometric approaches were applied for multivariate analysis and the selection of marker compounds that are characteristic of the coffee. Seventy-eight volatile compounds belonging to 13 chemical classes were tentatively identified, including six alcohols, five aldehydes, one carboxylic acid, three esters, 17 furans, one furanone, 13 ketones, two oxazoles, four phenolic compounds, 14 pyrazines, one pyridine, eight pyrroles and three sulfur-containing compounds.

Combination of vitamin E and vitamin C alleviates renal function in hyperoxaluric rats via antioxidant activity.

Hyperoxaluria and oxidative stress are risk factors in calcium oxalate (CaOx) stone formation. Supplement with antioxidant could be effective in prevention of recurrent stone formation. The present study aims to evaluate the protective effects of vitamin E and vitamin C in hyperoxaluric rat.

Determination of Mycotoxins in Brown Rice Using QuEChERS Sample Preparation and UHPLC-MS-MS.

QuEChERS sample preparation was optimized and validated using solvent extraction with 10% (v/v) acetic acid-containing acetonitrile in the presence of four salts (anh. MgSO4, NaCl, sodium citrate tribasic dihydrate and sodium citrate dibasic sesquihydrate) and dispersive solid-phase extraction with mixed sorbents (octadecylsilane, primary and secondary amine and silica sorbents) for an ultra high performance liquid chromatography-tandem mass spectrometric determination of nine mycotoxins in brown rice: aflatoxins (AFB1, AFB2, AFG1 and AFG2), fumonisins (FB1 and FB2), deoxynivalenol, ochratoxin A and zearalenone (ZON). Our developed method allows for the determination of trace levels of mycotoxins with method detection limits in the range of 1.

Separation selectivity patterns of fully charged achiral compounds in capillary electrophoresis with a neutral cyclodextrin.

Based on the separation selectivity equation, related to the dimensionless parameters for fully charged achiral analytes using a neutral CD, the separation selectivity can be classified into seven patterns. With respect to CZE without CD, the presence of CD in the buffer may improve, or reduce, the separation selectivity with this effect being accompanied by the same or reversed electrophoretic mobility order for charged analytes. This can depend on the separation selectivity of the two analytes in free solution, the binding selectivity, the separation selectivity of analyte-CD complexes and the ratio of electrophoretic mobility of the analytes in free, and complexed forms.

Investigation of neutral monolithic capillary columns with varying n-alkyl chain lengths in capillary electrochromatography.

Two different neutral nonpolar monolithic columns series (designated as A and B columns series) each consisting of three columns at varying n-alkyl chain length were prepared by the copolymerization of the functional monomers C8-methacrylate, C12-acrylate, or C16-methacrylate with the cross-linking monomer pentaerythritol triacrylate (PETA) to yield monoliths with surface bound C8, C12, and C16 chains. In the A columns series, the composition of the functional monomers and crosslinker was adjusted to yield comparable chromatographic retention regardless of the alkyl chain length. In the B columns series, the composition of the functional monomers and crosslinker was kept constant yielding chromatographic retention, which increased as expected in the order of increasing the n-alkyl chain length.

Determination of steroids adulterated in liquid herbal medicines using QuEChERS sample preparation and high-performance liquid chromatography.

QuEChERS sample preparation was optimized using solvent extraction with acetonitrile and dispersive-solid phase extraction with primary and secondary amine sorbents, and validated for high-performance liquid chromatographic determination of nine steroids commonly used to adulterate herbal medicines: such as triamcinolone, prednisolone, hydrocortisone, methylprednisolone, betamethasone, dexamethasone, beclomethasone, fludrocortsone acetate and cortisone acetate. Satisfactory extraction recoveries of 91-113% for all nine steroids were obtained, along with an acceptable precision in extraction recoveries shown by R.S.

Theoretical models of separation selectivity for charged compounds in micellar electrokinetic chromatography.

Equations and theoretical models for MEKC separation selectivity (α(MEKC) ) were established to explain a change in separation and electrophoretic mobility order of fully charged analytes, in which α(MEKC) is related to the dimensionless values of mobility selectivity in CZE (α(CZE)) and retention selectivity (α(k)) in MEKC, and where α(CZE) and α(k) are defined as the ratio of electrophoretic mobility in CZE and the ratio of retention factor (k) in MEKC for two charged analytes, respectively. Using four alkylparabens as test analytes, excellent agreement was found between the observed α(MEKC) and the proposed α(MEKC) models of test analytes in MEKC over a wide range of SDS concentrations and values of k. For example, in comparison with CZE separation of charged analytes, MEKC separation can enhance separation selectivity up to the maximum value when the selectivity ratio (ρ) is greater than 1.

Comparison and prediction of the retention in micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for disubstituted benzenes.

Retention index (I), rather than retention factor (k), was found to be a more reasonable parameter for comparison of the relative affinity of disubstituted benzenes in MEEKC and MEKC, due to independent of I with the SDS surfactant concentration. MEKC and MEEKC may give similar or different I values, depending on types of moieties. With known I and K(ow) for alkylbenzenes as references in MEKC and MEEKC, the values of K(ow) for disubstituted benzenes can be estimated from the observed I values, where K(ow) is the octanol-water distribution constant.

Selectivity comparisons of monolithic silica capillary columns modified with poly(octadecyl methacrylate) and octadecyl moieties for halogenated compounds in reversed-phase liquid chromatography.

Stationary phase selectivities for halogenated compounds in reversed-phase HPLC were compared using C18 monolithic silica capillary columns modified with poly(octadecyl methacrylate) (ODM) and octadecyl moieties (ODS). The preferential retention of halogenated benzenes on ODM was observed in methanol/water and acetonitrile/water mobile phases. In selectivity comparison of selected analytes on ODM and ODS, greater selectivities for halogenated compounds were obtained with respect to alkylbenzenes on an ODM column, while similar selectivities were observed with a homologous series of alkylbenzenes on ODM and ODS columns.

Capillary zone electrophoresis for separation and analysis of hydroxycitric acid and hydroxycitric acid lactone: application to herbal products of Garcinia atroviridis Griff.

Capillary zone electrophoresis (CZE) was developed for quantitative determination of hydroxycitric acid and hydroxycitric acid lactone in herbal products of Garcinia atroviridis Griff. Resolution optimization was investigated by varying type, concentration and pH of buffers. Using the pH 9.

Comparison of resolution in microemulsion EKC and MEKC employing suppressed electroosmosis: application to bisphenol-A-diglycidyl ether and its derivatives.

The resolution (R(s)) of hydrophobic analytes in microemulsion EKC (MEEKC) and MEKC with suppressed electroosmosis was investigated using bisphenol-A-diglycidyl ether and its derivatives (BADGEs) as test analytes. Separation scales were compared using our equation for the resolution, R(s)= (square rootN/4)(alpha-1)/(1+K(2)),where k is the retention factor, alpha the selectivity (alpha = k(2)/k(1) for k(2) > or = k(1)>0), and N the average efficiency. At given concentrations of SDS and organic cosolvent in the buffer, in comparison with MEKC, MEEKC was found to provide better resolution of BADGEs, mainly due to the significantly smaller k in MEEKC, but not the greater alpha in MEEKC, while a comparable range of N.

Retention factor and retention index of homologous series compounds in microemulsion electrokinetic chromatography employing suppressed electroosmosis.

The retention factor (k) and retention index (I) of homologous series compounds such as alkylbenzenes (BZ), alkylaryl ketones, alkylbenzoates, and alkylparabens in microemulsion electrokinetic chromatography (MEEKC) with suppressed electroosmosis were investigated in a wide range of SDS concentrations ([SDS]), temperatures, and concentrations of organic cosolvents (phi). Using BZ as standards, the retention indices of other homologous series compounds were determined and they were found to be independent of [SDS] and temperature, while are dependent on the types and concentrations of organic cosolvents. The retention factor linearly increases with increasing [SDS], while linearly decreases with increasing temperature.

Microemulsion electrokinetic chromatography for separation and analysis of curcuminoids in turmeric samples.

Microemulsion EKC (MEEKC) was developed for quantitative analysis of curcuminoids, such as curcumin (C), demethoxycurcumin (D), and bis-demethoxycurcumin (B). MEEKC separation of curcuminoids was optimized, and a change in resolution was explained using a modified equation for resolution in MEEKC without electroosmosis. The suitable MEEKC conditions for separation of curcuminoids were obtained to be the microemulsion buffer containing 50 mM phosphate buffer at pH 2.

Chiral separation in capillary electrophoresis using dual neutral cyclodextrins: theoretical models of electrophoretic mobility difference and separation selectivity.

Simple equations and theoretical models, related to enantioselectivity (kappa) and C, have been developed for prediction of electrophoretic mobility difference (Deltamu) and separation selectivity (alpha) for enantiomers in CE using dual CDs, where alpha and kappa are defined as the ratio of mu and the ratio of binding constant (K) for enantiomers to each CD, respectively, C the CD concentration, and the average K for enantiomers and each CD. Experiments were carried out using dual CDs as beta-CD and dimethyl-beta-cyclodextrin (DM-beta-CD) and test analytes as five pairs of amphetamine drug enantiomers. A change in observed Deltamu and alpha of enantiomers in dual CDs was found to be in excellent agreement with the theoretical models.

Determination of gibberellic acid in fermentation broth and commercial products by micellar electrokinetic chromatography.

Micellar electrokinetic chromatography (MEKC) was developed as a method for quantitative determination of gibberellic acid (GA3) in fermentation broth and commercial products, using 25 mM disodium tetraborate as a buffer at pH 9.2 and 100 mM sodium dodecyl sulfate as a micellar phase. The baseline resolution (Rs of GA3 from other compounds in fermentation broth was achieved with Rs > 2.

New halimane diterpenoids from Croton oblongifolius.

Three new halimane-type diterpenoids, crotohalimaneic acid ( 1), crotohalimoneic acid ( 2) and 12-benzoyloxycrotohalimaneic acid ( 3), were isolated from the stem bark of Croton oblongifolius Roxb. Their structures were established on the basis of spectroscopic and X-ray analysis. Compounds 1 and 2 showed non-specific strong cytotoxicity against a panel of human tumor cell lines; whereas 3 was inactive.