Headspace solid phase microextraction in-situ supercritical fluid extraction coupled to gas chromatography-tandem mass spectrometry for simultaneous determination of perfluorocarboxylic acids in sediments

Headspace solid phase microextraction (HS-SPME) in-situ supercritical fluid extraction (SFE) was investigated for the determination of trace amounts of perfluorocarboxylic acids (PFCAs) in sediments. Quantitation was performed by using gas chromatography coupled to negative chemical ionization-tandem mass spectrometry (GC-NCI-MS/MS). The optimum conditions of HS-SPME following SFE were obtained using 500 μL n-butanol as a derivatization reagent in supercritical carbon dioxide with static extraction for 10 min, then dynamic extraction for 20 min at 30 MPa and 70 °C and simultaneous collected with 100 μm film thickness PDMS fiber. The linear range of proposed method was from 5 to 5000 ng g(-1), with limit of detection ranging from 0.39 to 0.54 ng g(-1) and limit of quantitation ranging from 1.30 to 1.80 ng g(-1). The developed method was successfully applied to analyze PFCAs in sediments from rivers and beach near industrial areas. The concentrations of PFCAs determined are from 282 to 4473 ng g(-1).     

Full automatic determination of chlorophenols in water using solid-phase microextraction/on-fiber derivatization and gas chromatography-mass spectrometry

A fully automated combination of solid-phase microextraction and on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed to determine 17 chlorophenols in aqueous samples. Optimal parameters for the automated process, such as fiber coating (polyacrylate), derivatization reagent (N,O-bis(trimethylsilyl) trifluoroacetamide), extraction time (60 min), derivatization time (5 min), incubation temperature (35°C), sample pH (3), and ionic strength (300 g L(-1) of NaCl), as well as desorption time (5 min) and desorption temperature (270°C) were established. The whole procedure took only 90 min and was performed automatically. The shortcomings of silylation derivatives, like incompleteness and instability, were overcome by using solid-phase microextraction on-fiber silylation in this study. The results from both pure water and river water samples showed that the method had a good linearity (r(2) = 0.9993-1.0000), ranging from 0.01 to 100 μg L(-1). The related standard deviations were between 3.6 and 10.0%. The limits of detections and qualifications ranged from 0.03 to 3.11 ng L(-1) and 0.09 to 10.4 ng L(-1) for the CPs, respectively. The proposed method is superior to traditional solid phase extraction procedure.     

Simultaneous analysis of aspartame and its hydrolysis products of Coca-Cola Zero by on-line postcolumn derivation fluorescence detection and ultraviolet detection coupled two-dimensional high-performance liquid chromatography

An innovative two-dimensional high-performance liquid chromatography system was developed for the simultaneous analysis of aspartame and its hydrolysis products of Coca-Cola Zero. A C8 reversed-phase chromatographic column with ultraviolet detection was used as the first dimension for the determination of aspartame, and a ligand-exchange chromatographic column with on-line postcolumn derivation fluorescence detection was employed as the second dimension for the analysis of amino acid enantiomers. The fluorimetric derivative reagent of amino acid enantiomers was o-phthaldialdehyde. The hydrolysis of aspartame in Coca-Cola Zero was induced by electric-heating or microwave heating. Aspartame was quantified by the matrix matched external standard calibration curve with a linear concentration range of 0-50 μg mL(-1) (r(2)=0.9984). The limit of detection (LOD) and the limit of quantification (LOQ) were 1.3 μg mL(-1) and 4.3 μg mL(-1), respectively. The amino acid enantiomers was analyzed by the matrix matched internal standard calibration method (D-leucine as the internal standard) with a linear concentration range of 0-10 μg mL(-1) (r(2)=0.9988-0.9997). The LODs and LOQs for L- and D-aspartic acid and L- and D-phenylalanine were 0.16-0.17 μg mL(-1) and 0.52-0.55 μg mL(-1), respectively, that was 12-13 times more sensitive than ultraviolet detection. The overall analysis accuracy for aspartame and amino acid enantiomers was 90.2-99.2% and 90.4-96.2%, respectively. The overall analysis precision for aspartame and amino acid enantiomers was 0.1-1.7% and 0.5-6.7%, respectively. Generally, the extent of aspartame hydrolysis increases with the increase of electro-thermal temperature, microwave power, and the duration of hydrolysis time. D-aspartic acid and D-phenylalanine can be observed with the electro-thermal racemization at the hydrolysis temperature 120°C for 1 day and only D-aspartic acid can be observed at the hydrolysis temperature 90°C for 2 and 3 days. For the microwave induced hydrolysis, only L-aspartic acid was detected at the power 560 W for 1 min and 320 W for 3 min.     

N,N-dimethyl-trimethylsilyl-carbamate as a derivatizing agent in gas chromatography of trichothecene mycotoxins

N,N-dimethyl-trimethylsilyl-carbamate, a commercially available silylating agent, has been tested in the derivatization of trichothecenes for the first time. Its reaction with alcohols is an autocatalytic, non-equilibrium process with volatile by-products. As a consequence of these advantageous characteristics N,N-dimethyl-trimethylsilyl-carbamate proved to be easily utilizable and effective for the derivatization of all studied trichothecenes, namely deoxynivalenol (DON), nivalenol (NIV) and 4,15-diacetoxyscirpenol (DAS). During testing also, optimum conditions (temperature: 15 °C, reaction time: 35 min) were established for the trimethylsilylation and for the gas chromatographic determination of the above-mentioned three trichothecenes. The linearity of the detector response was found to be proper in the 5-1100 ng range. (Given in the grams of trichothecene equivalent to the derivatives injected). The limit of detection is less than 1 ng for each of the studied trichothecenes. Relative standard deviations of the peak heights ranged from 0.75 to 4.32%.     

Determination of memantine in plasma and vitreous humour by HPLC with precolumn derivatization and fluorescence detection

A new HPLC procedure with precolumn derivatization and rimantadine as the internal standard for determining memantine, a candidate agent for the treatment of glaucoma in plasma and vitreous humour, has been developed and validated. Precolumn derivatization was performed with 9-fluorenylmethyl-chloroformate-chloride (FMOC-Cl) as the derivatization reagent and followed by a liquid-liquid extraction with n-hexane. Optimal conditions for derivatization were an FMOC-Cl concentration of 1.5 mM, a reaction time of 20 min, the temperature at 30°C, the borate buffer pH 8.5, and a borate buffer-acetonitrile ratio of 1:1. The derivatives were analyzed by isocratic HPLC with the fluorescence detector λex 260 nm λem 315 nm on a Novapack C(18) reversed-phase column with a mobile phase of acetonitrile-water (73:27, v/v), 40°C, and a flow rate of 1.2 mL/min. The linear range was 10-1000 ng/mL with a quantification limit of ～ 10 ng/mL for both types of samples. This analytical method may be suitable for using in ocular availability studies.     

Optimization of large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry analysis for the determination of estrogenic compounds in environmental samples

Large volume injection-programmable temperature vaporization-gas chromatography-mass spectrometry (LVI-PTV-GC-MS) was optimized for the determination of estrone (E1), 17β-estradiol (E2), 17α-ethynyl estradiol (EE2), mestranol (MeEE2) and estriol (E3) for their determination in environmental samples (estuarine water, wastewater, fish bile and fish homogenate) after derivatization with 25 μL (BSTFA+1% TMCS) and 125 μL of pyridine. Experimental designs such as Plackett-Burman (PBD) and central composite designs (CCDs) were used to optimize the LVI-PTV variables (cryo-focusing temperature, vent time, vent flow, vent pressure, injection volume, purge flow to split vent, splitless time and injection speed). Optimized conditions were as follows: 45 μL of n-hexane extract are injected at 60°C and 6 μL/s with a vent flow and a vent pressure of 50 mL/min and 7.7 psi, respectively, during 5 min; then the split valve is closed for 1.5 min and afterwards the injector is cleaned at 100 mL/min before the next injection. The method was applied to the determination of estrogenic compounds in environmental samples such as estuarine water, wastewater, and fish homogenate and bile. Limits of detection (0.04-0.15 ng/L for water samples, 0.04-0.67 ng/g for fish bile and 0.1-7.5 ng for fish homogenate) obtained were approx. ten times lower than those obtained by means of a common split/splitless inlet.     

Simple derivatization of aldehydes with D-cysteine and their determination in beverages by liquid chromatography-tandem mass spectrometry

We describe a simple derivatization method to determine aldehydes. This method is based on derivatization with D-cysteine and consecutive liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimum derivatization conditions of aldehydes with D-cysteine were 10 min at 50°C and pH 7.0. The formed alkyl thiazolidine-4-carboxylic acid derivatives were directly injected in LC-MS/MS. In the established condition, the method was used to detect eight aldehydes in beverages. The limit of detection (LOD) and limit of quantification (LOQ) of the aldehydes were 0.2-1.9 μg L(-1) and 0.7-6.0 μg L(-1) and the relative standard deviation was less than 2.0% at concentrations of 0.1 mg L(-1) and 1.0 mg L(-1) with the exception of octanal. All the beverage samples had detectable levels of methanal (0.033-0.145 mg L(-1)), ethanal (0.085-2.12 mg L(-1)), propanal (ND to 0.250 mg L(-1)), butanal (ND to 0.003 mg L(-1)), pentanal (ND to 0.471 mg L(-1)), hexanal (ND to 0.805 mg L(-1)), heptanal (0.019-3.91 mg L(-1)) and octanal (0.029-0.118 mg L(-1)).     

Simple and automatic determination of aldehydes and acetone in water by headspace solid-phase microextraction and gas chromatography-mass spectrometry

We describe a simple and automatic method to determine nine aldehydes and acetone simultaneously in water. This method is based on derivatization with 2,2,2-trifluoroethylhydrazine (TFEH) and consecutive headspace-solid-phase microextraction and gas chromatography-mass spectrometry. Acetone-d(6) was used as the internal standard. Aldehydes and acetone in water reacted for 30 min at 40°C with TFEH in a headspace vial and the formed TFEH derivatives were simultaneously vaporized and adsorbed on polydimethylsiloxane-divinylbenzene. Under the established condition, the method detection limit was 0.1-0.5 μg/L in 4 mL water and the relative standard deviation was less than 13% at concentrations of 0.25 and 0.05 mg/L. This method was applied to determine aldehydes and acetone in 5 mineral water and 114 surface water samples. All mineral water samples had detectable levels of methanal (24.0-61.8 μg/L), ethanal (57.7-110.9 μg/L), propanal (11.5-11.7 μg/L), butanal, pentanal (3.3-3.4 μg/L) and nonanal (0.3-0.4 μg/L). Methanal and ethanal were also detected in concentration range of 2.7-117.2 and 1.2-11.9 μg/L, respectively, in surface water of 114 monitoring sites in Korea.     

Identification and quantification of six major α-dicarbonyl process contaminants in high-fructose corn syrup

High-fructose corn syrup (HFCS) is a widely used liquid sweetener produced from corn starch by hydrolysis and partial isomerization of glucose to fructose. During these processing steps, sugars can be considerably degraded, leading, for example, to the formation of reactive α-dicarbonyl compounds (α-DCs). The present study performed targeted screening to identify the major α-DCs in HFCS. For this purpose, α-DCs were selectively converted with o-phenylendiamine to the corresponding quinoxaline derivatives, which were analyzed by liquid chromatography with hyphenated diode array-tandem mass spectrometry (LC-DAD-MS/MS) detection. 3-Deoxy-D-erythro-hexos-2-ulose (3-deoxyglucosone), D-lyxo-hexos-2-ulose (glucosone), 3-deoxy-D-threo-hexos-2-ulose (3-deoxygalactosone), 1-deoxy-D-erythro-hexos-2,3-diulose (1-deoxyglucosone), 3,4-dideoxyglucosone-3-ene, methylglyoxal, and glyoxal were identified by enhanced mass spectra as well as MS/MS product ion spectra using the synthesized standards as reference. Addition of diethylene triamine pentaacetic acid and adjustment of the derivatization conditions ensured complete derivatization without de novo formation for all identified α-DCs in HFCS matrix except for glyoxal. Subsequently, a ultra-high performance LC-DAD-MS/MS method was established to quantify 3-deoxyglucosone, glucosone, 3-deoxygalactosone, 1-deoxyglucosone, 3,4-dideoxyglucosone-3-ene, and methylglyoxal in HFCS. Depending on the α-DC compound and concentration, the recovery ranged between 89.2% and 105.8% with a relative standard deviation between 1.9% and 6.5%. Subsequently, the α-DC profiles of 14 commercial HFCS samples were recorded. 3-Deoxyglucosone was identified as the major α-DC with concentrations up to 730 μg/mL HFCS. The total α-DC content ranged from 293 μg/mL to 1,130 μg/mL HFCS. Significantly different α-DC levels were not detected between different HFCS specifications, but between samples of various manufacturers indicating that the α-DC load is influenced by the production procedures.     

Simultaneous determination of five polyether ionophores using liquid chromatography with one-step fluorescent derivatization

We present a selective method for simultaneous determination of five polyether ionophores such as salinomycin (SAL), monensin (MON), narasin (NAR), semduramicin (SEM) and lasalocid (LAS) in aquatic samples using a liquid chromatography with one-step fluorescent derivatization of 2-(4-hydrazinocarbonyl-phenyl) 4,5-diphenylimidazole (HCPI) and 4-(4,5-diphenyl-1H-imidazol-2-yl) benzoyl chloride hydrochloride (DIB-Cl). Fluorescent one-step derivatization for SAL, MON, NAR and SEM using HCPI and for LAS using DIB-Cl was monitored by an LC/fluorescence detector (E(x), 340 nm; E(m), 465 nm). Chromatographic separation was performed on a TSK-GEL ODS-120T (4.6 × 150 mm, 3 μm) column using a mobile phase of 0.1% formic acid in acetonitrile and 0.5 mM ammonium formate in water (70/30, v/v). The limits of detections were 0.01 μg/mL (50 pg) for LAS, 0.05 μg/mL (250 pg) for SAL, NAR and SEM, and 0.1 μg/mL (500 pg) for MON, respectively. The recoveries for water samples were indicated to be the range of 79.6 ± 6.4 - 99.0 ± 4.4% with associated precision values (between-day for 3 days) for repeatability. Based on solid-phase extraction, the limit of quantitation values indicated 0.1 ng/mL for SAL, MON, NAR and SEM, and 0.01 ng/mL for LAS in water samples.     

Simultaneous determination of bisphenol A, triclosan, and tetrabromobisphenol A in human serum using solid-phase extraction and gas chromatography-electron capture negative-ionization mass spectrometry

This study aimed at optimizing and validating a sensitive method for simultaneous determination of bisphenol A (BPA), triclosan (TCS), and tetrabromobisphenol A (TBBPA) in human serum using solid-phase extraction (SPE) and gas chromatography coupled to electron-capture negative-ionization mass spectrometry (GC-ECNI/MS). Sample preparation involved denaturation of serum proteins with formic acid followed by SPE on an Oasis HLB cartridge. Fractionation was performed on Florisil from which the phenolic compounds were eluted with methanol-dichloromethane (DCM) (5:1, v/v). The phenolic fraction was further derivatized with pentafluoropropionic acid anhydride (30 min at 70 degrees C). Further liquid-liquid partitioning using hexane-DCM (4:1, v/v) and K(2)CO(3) 3% aqueous solution was used to eliminate excess reagent and acidic by-products formed during derivatization. The cleaned extract was injected into a GC-ECNI/MS system operated in selected ion monitoring mode. For thorough method validation, each step of the procedure was rigorously optimized. The method limits of quantitation for BPA, TCS, and TBBPA were 0.28 ng mL(-1), 0.09 ng mL(-1) and 0.05 ng mL(-1), respectively. Furthermore, the method was applied to 21 Belgian human serum samples. The median concentrations obtained for BPA (0.71 ng mL(-1)) and TCS (0.52 ng mL(-1)) in Belgian human serum samples were similar to previously reported data for human fluids. Slightly higher levels of TBBPA (0.08 ng mL(-1)) were found in Belgium samples compared to Norwegian serum.     

Sorptive extraction with in-sample acetylation for gas chromatography-mass spectrometry determination of ethylphenol species in wine samples

An inexpensive and effective sample preparation procedure for the determination of three ethylphenolic off-flavours (4-ethylphenol, 4-ethylguaiacol and 4-ethylcathecol) in wine samples is presented. Analytes were in situ acetylated and concentrated using a disposable silicone sorbent (DSS) exposed to the diluted sample. After that, the analytes were recovered with ethyl acetate and determined by gas chromatography with mass spectrometry. The influence of different parameters (volume of acetic anhydride, basic catalyst, ionic strength, sorbent format, sampling mode and extraction time) on the efficiency of derivatization and extraction steps is discussed. Under optimized conditions, 2 mL of wine were diluted with 15 mL of an aqueous solution of potassium bicarbonate (5%, m/v) in a 22 mL vessel, containing 2 g of sodium chloride. The volume of acetic anhydride and the extraction time were set at 90 μL and 2 h, and the extraction was carried out at room temperature (20±2°C). Analytes were concentrated using a silicone disc (5 mm diameter × 0.5 mm thickness) and further desorbed with 0.2 mL of ethyl acetate. The achieved limits of quantification (LOQs), defined as the concentration of each compound providing a signal 10 times higher than the baseline noise, stayed between 5 and 15 ng mL(-1). The method provided a linear response range of up to 5000 ng mL(-1) and relative recoveries from 91% to 116%. The 4-ethylphenol off-flavour was detected in most red wine samples at concentrations of up to 2700 ng mL(-1).     

Employing ultra high pressure liquid chromatography as the second dimension in a comprehensive two-dimensional system for analysis of Stevia rebaudiana extracts

Stevia rebaudiana extracts and plant materials are increasingly used as natural sweeteners. Polyphenolic and stevioside compounds contained in S. rebaudiana extracts were separated by comprehensive LC. A polyamine column operated in normal phase mode was used for the first dimension separation (D1), and a UHPLC C18 column operated in reversed phase mode was used for the second dimension separation (D2). The sub-2 μm column (2.1 mm × 30 mm, maintained at 70°C) and the UHPLC pump employed for D2 elution allowed a separation/cycle time of 20 s, with a backpressure oscillating between 805 and 922 bar at 3.4 mL/min. The reduced D2 cycle time allowed 3-12 D2 samplings for each peak eluted by D1. Polyphenolic and stevioside compounds were identified by combining the information coming from the position of the compounds in the 2D plot and UV spectra with that of reference materials.     

Development and validation of two methods based on high-performance liquid chromatography-tandem mass spectrometry for determining 1,2-benzopyrone, dihydrocoumarin, o-coumaric acid, syringaldehyde and kaurenoic acid in guaco extracts and pharmaceutical preparations

In this study, two HPLC-ESI-MS/MS methods were developed and validated for the determination of 1,2-benzopyrone (COU), o-coumaric acid (OCA), kaurenoic acid (KAU), syringaldehyde (SYR), and dihydrocoumarin (DIH) in guaco extracts and pharmaceutical preparations (syrup and oral solution). The chromatographic separation was achieved using a C18 XBridge 150×2.1-mm (5-μm particle size) column maintained at 25°C. The mobile phases consisted of a gradient of water and acetonitrile containing 0.05% formic acid or 5 mM ammonium formate for the positive and negative ion modes, respectively. All of the calibration curves showed excellent coefficients of correlation (r≥0.9970) over the ranges of 1.25-400 ng/mL for coumarin, 10-600 ng/mL for dihydrocoumarin, 5-250 ng/mL for KAU, and 25-500 ng/mL for o-coumaric acid and syringaldehyde. The range of recovery was 96.3-103% with an RSD% of <4.85% for intraday and interday precision. The results indicate that the developed methods are fast, efficient, and sensitive for the quantification of the guaco metabolites in extracts and pharmaceutical forms while avoiding purification and derivatization steps.     

Determination of hexanal as an oxidative marker in vegetable oils using an automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer

An automated dynamic headspace sampler coupled to a gas chromatograph/mass spectrometer was evaluated as an oxidative marker to determine hexanal content in vegetable oils. For the effective analysis, a cooled injection system (CIS) was used to focus and to introduce the hexanal desorbed from the Tenax TA. The temperature of the CIS was maintained at -60 °C for 12 min before desorbing the hexanal. Hexanal was separated on a capillary column (DB-5, 0.25 mm × 60 m, 0.25 μm in film thickness) from 50 to 230 °C, followed by mass spectrometer-selected ion monitoring analysis at m/z 56. The instrumental response to hexanal was highly linear from 10 ng mL(-1) to 1 μg mL(-1) (r(2) = 0.9999). The relative standard deviation (RSD) of intra- and inter-day repeatability was acceptable, with values of less than 3.88 and 4.25%, respectively. The LOD and LOQ of hexanal were determined by gas chromatograph/mass spectrometer-selected ion monitoring to be 3.3 and 9.8 ng mL(-1), respectively. The acid value, peroxide value and fatty acid composition revealed a good correlation with the hexanal concentration.     

Optimization of extraction of evodiamine and rutaecarpine from fruit of Evodia rutaecarpa using modified supercritical CO(2)

Evodiamine and rutaecarpine have been intensively studied due to their pharmacological actions and clinical applications. In this report, supercritical fluid was used to extract evodiamine and rutaecarpine from the unripe fruit of Evodia rutaecarpa. Response surface methodology using Box-Behnken experimental design was utilized to optimize parameters for supercritical carbon dioxide extraction with methanol as co-solvent. The effect of various values of dynamic extraction time (30-90min), temperature (50-70°C) and pressure (200-400bar) on extraction yields of the two compounds was evaluated. Determinations of the extracts were performed by high-performance liquid chromatography. The experimental data obtained were fitted to second-order polynomial equations and analyzed by analysis of variance. The highest yields predicted were 1.217mg/g for evodiamine and 0.969mg/g for rutaecarpine at the optimal values (time 78min, temperature 62°C, pressure 280bar and co-solvent flow rate 0.4mL/min), based on the selected range of experimental conditions.     

指示离子Cd2+测定维生素B1的方波极谱法研究

根据Cd2+对维生素B1(VB1)的指示作用,建立了用方波极谱法测定VB1的新方法.在氨-氯化铵缓冲溶液中,VB1不出峰,加入Cd2+后在-0.856 V(vs.SCE)处出现1个固定还原峰,并在-0.360 V(vs.SCE)处可见1个峰高与VB1浓度呈正比的还原峰.依据该还原峰峰高的变化规律可测定VB1的含量.VB1在1.35μg/mL~1.35 mg/mL的范围内有良好的线性关系,检出限可达0.13μg/mL,r为0.999 7.平均加样回收率为99.6%(n=9),RSD为0.9%.利用方法测定营养胶囊中VB1的含量,效果理想,可作为VB1含量的测定方法.     

Simultaneous determination of nine endogenous steroids in human urine by polymeric-mixed micelle capillary electrophoresis

A new CE system based on the use of polymeric-mixed micelles (cholic acid, SDS and the poloxamine Tetronic(?) 1107) was developed for the simultaneous determination of nine steroids in human urine. This method allows the baseline separation and quantitation of cortisol, androstenedione, estriol, dehydroepiandrosterone sulfate, testosterone, dehydroepiandrosterone, estrone, progesterone and estradiol in less than 25 min showing to be sensitive enough to detect low concentrations of these steroids in urine samples (5-45 ng/mL). The optimized electrophoretic conditions were performed using a 50 cm × 75 μm capillary, 18 kV, 25°C, with 44 mM cholic acid, 10 mM SDS, 0.05% w/v tetronic(?) 1107, 2.5% v/v methanol, 2.5% v/v tetrahydrofuran in 5 mM borate - 5 mM phosphate buffer (pH=8.0) as a background electrolyte and a dual 210/254 UV-detection. The method can simultaneously determine 0.1-120 μg/mL, which corresponds to 5-6000 ng/mL of steroids in 2 mL urine. The recoveries ranged between 82.4 and 101.5%. Due to its simplicity, speed, accuracy and reliability, the proposed method could be a potential alternative to the traditional methodologies used with clinical purposes.     

Quantification of 2,5-dimethyl-4-hydroxy-3(2H)-furanone using solid-phase extraction and direct microvial insert thermal desorption gas chromatography-mass spectrometry

A GC-MS method for the determination of furaneol in fruit juice was developed using Lichrolut-EN solid-phase extraction (SPE) coupled to microvial insert thermal desorption. Lichrolut-EN can effectively extract furaneol from juice, and had much less retention for pigments and other non-volatiles than HLB and C18 columns. The furaneol can be completely eluted out from the Lichrolut-EN SPE column with 1mL of methanol, which can be directly analyzed on GC-MS using an automated large volume microvial insert thermal desorption technique without further purification and concentration. The method is sensitive, has good recovery (98%) and reproducibility (CV<4%). The concentration of furaneol in some commonly grown strawberry, raspberry, and blackberry cultivars in Pacific Northwest of the United States was determined. Strawberries had the highest concentration of furaneol with 'Totem' and 'Pinnacle' cultivars over 13mgkg(-1) fruit. 'Marion' blackberry had 5 times more furaneol than 'Black Diamond', and 16 times more than 'Thornless Evergreen' blackberry. Raspberries had furaneol concentration ranged from 0.8 to 1.1mgkg(-1) fruit.     

Microwave-assisted extraction (MAE) combined with gas chromatography–mass spectrometry (GC–MS) for determination of volatile small molecules to evaluate compatibility of antimicrobial peptide PL-5 spray with packaging materials

A simple and efficient method involving microwave-assisted extraction (MAE) combined with GC–MS was established to determine 1,3-di-tert-butylbenzene (DBB), 2,4-di-tert-butylphenol (DBP), 3,5-di-tert-butyl-4-hydroxybenzaldehyde (DBHBA) for evaluating the compatibility of antimicrobial peptide PL-5 spray with drug-packaging materials. In this study, the antimicrobial peptide PL-5 spray was purified using a Welchrom C18 column, and the high-density polyethylene spray bottle with liquid collection tube was first mixed with absolute ethanol, which would be subjected to MAE for further measurement by GC–MS. Various experimental parameters were systematically optimized, and good linearities were obtained within the range of 0.05–1.00 μg/mL for DBB and DBHBA and 0.50–10.00 μg/mL for DBP, with limits of detection (LODs) of 0.99 ng/mL (DBB), 16.34 ng/mL (DBP), and 1.64 ng/mL (DBHBA). Satisfactory recoveries that ranged from 96.0% to 107.2% were acquired, and the relative standard deviation was ≤ 4.7%. The results showed that the maximum daily usage of DBB, DBP, and DBHBA was 9.859, 163.445, and 16.399 ng, respectively, which was far below the corresponding permitted daily exposure values according to the safety assessment, indicating that the migration of analytes did not bring any potential safety risk. The compatibility between the drug and the packaging materials was favorable.