Solid-phase Microextraction Sampling Research Articles

Wearable solid-phase microextraction sampling for enhanced detection of volatile analytes in human ears

BackgroundInvestigating ear at molecule level is challenging task, since there is a lack of molecular detection by traditional diagnosis techniques such as otologic endoscopy, ear swab culture, and imaging diagnostic technique. Therefore, new development of noninvasive, highly sensitive, and convenient analytical method for investigating human ears is highly needed. ResultsWe developed a wearable sampling device for extracting trace analytes in ear by fixing solid-phase microextraction fibers into modified earmuffs (SPME-in-earmuffs). After sampling, SPME fiber was coupled with gas chromatography-mass spectrometry (GC-MS) for identification and quantification of extracted analytes. Enhanced detection of various analytes such as volatile metabolites, exposures, and therapeutic drugs of ears were demonstrated in this work. Particularly, sport-induced metabolic changes such as fatty acids, aldehyde compounds and oxidative produces were found from human ears using this method. Acceptable analytical performances were obtained by using this newly developed method for detecting ear medicines, e.g., low limit of detection (LOD, 0.005–0.021 ng/mL) and limit of quantification (LOQ, 0.018–0.071 ng/mL), excellent linear dynamic responses (R2 > 0.99, ranging from 0.050–8.00 ng/mL), good relative standard deviations (RSDs, 13.19 % ∼ 21.40 %, n = 6) and accuracy (84.43–150.18 %, n = 6) at different concentrations. SignificanceFor the first time, this work provides a simple, convenient, and wearable microextraction method for enhanced detection of trace volatiles in human ears. The enclosed space between ear and earmuff allows headspace SPME sampling of volatile analytes, and thus provides a new wearable method for monitoring ear metabolites and human exposures, showing potential applications in human health, disease diagnosis, and sport science.

Effect of volatile compounds produced by Weissella cibaria BWL4 on Botrytis cinerea infection in fruit and complete genome sequence analysis of BWL4

Botrytis cinerea, one of the most harmful pathogenic fungi, causes significant postharvest decay in fruit. In this study, the effects of Weissella cibaria BWL4 on B. cinerea and the gray mold in grape and kiwifruit were evaluated. Additionally, the genome of an antagonistic bacterium BWL4 was sequenced. Results showed that the application of BWL4 inhibited B. cinerea infection in grape and kiwifruit. BWL4 produced antifungal volatile substances against B. cinerea. A gas chromatography–mass spectrometry of solid phase microextraction samples (SPME-GC-MS) analysis showed that BWL4 produced 54 volatiles. Among these volatiles, furfural, 2,6-dimethyl-pyrazine, dimethyl trisulfide, 2-pentyl furan, 2-ethyl hexanol, hexamethyl-cyclotrisiloxane, dodecamethyl-cyclohexasiloxane, 2,4-di-tert-butylphenol, and butylated hydroxytoluene, exhibited antifungal activity against B. cinerea, with MICs of 0.8 g L−1, 0.2 g L−1, 0.9 g L−1, 5 g L−1, 0.4 g L−1, 8 g L−1, 8 g L−1, 80 mg L−1, and 2 g L−1, respectively. In vivo assay showed that these compounds inhibited the disease development in kiwifruit. These compounds except dimethyl trisulfide can also inhibit gray mold in grape. The genome of W. cibaria BWL4 consists of a circular chromosome of 2.42 Mb and 6 plasmids. The genome size is 2.53 Mb, encoding 2327 putative genes. Several genes involved in the biosynthesis of some antifungal volatiles and 17 genes associated with biocontrol were identified. These results suggested that W. cibaria BWL4 can be considered as an effective biological control agent for the postharvest management of B. cinerea infection.

Artificial Intelligence Sensing: Effective Flavor Blueprinting of Tea Infusions for a Quality Control Perspective.

Tea infusions are the most consumed beverages in the world after water; their pleasant yet peculiar flavor profile drives consumer choice and acceptance and becomes a fundamental benchmark for the industry. Any qualification method capable of objectifying the product's sensory features effectively supports industrial quality control laboratories in guaranteeing high sample throughputs even without human panel intervention. The current study presents an integrated analytical strategy acting as an Artificial Intelligence decision tool for black tea infusion aroma and taste blueprinting. Key markers validated by sensomics are accurately quantified in a wide dynamic range of concentrations. Thirteen key aromas are quantitatively assessed by standard addition with in-solution solid-phase microextraction sampling followed by GC-MS. On the other hand, nineteen key taste and quality markers are quantified by external standard calibration and LC-UV/DAD. The large dynamic range of concentration for sensory markers is reflected in the selection of seven high-quality teas from different geographical areas (Ceylon, Darjeeling Testa Valley and Castleton, Assam, Yunnan, Azores, and Kenya). The strategy as a sensomics-based expert system predicts teas' sensory features and acts as an AI smelling and taste machine suitable for quality controls.

A Rapid Method to Predict Beer Shelf Life Using an MS-Based e-Nose

A rapid and efficient technique was applied, which used an electronic nose based on a mass detector (MS-based e-nose) combined with headspace solid-phase microextraction sampling and chemometric tools to classify beer samples between fresh and aged and between samples contained in aluminium cans or glass bottles, and to predict the shelf life of beer. The mass spectra obtained from the MS-based e-nose contained details about volatile compounds and were recorded as the abundance of each ion at different mass-to-charge (m/z) ratios. The analysis was performed on 53 naturally aged samples for eleven months without light and with a controlled temperature of around 14 °C ± 0.5 °C. Principal component analysis (PCA) was performed on the data and showed a grouping of samples between fresh and aged. Partial least square discriminant analysis (PLS-DA) allowed the discrimination of fresh from aged beers but could not discriminate between the samples according to the type of packaging. Finally, partial least squares regression (PLSR) proved to be an effective method for predicting beer shelf life.

Exploring the optimal electropolymerization strategy for the preparation of solid-phase microextraction fibers using pyrrole-dopamine copolymers

In-situ electropolymerization of conductive polymers on the surface of stainless-steel substrates is a well-established but promising procedure for the preparation of solid-phase microextraction (SPME) tools. Herein, different electrochemical methods including constant potential (CP), constant potential pulse (CPP), and cyclic voltammetry (CV) were utilized to fabricate SPME fibers by in-situ electropolymerization of pyrrole-dopamine copolymers (PPY/PDA) on the surface of stainless-steel fibers. The coated fibers were characterized and applied for the direct-immersion SPME (DI-SPME) sampling of ultra-trace amounts of plant hormones including abscisic acid (ABA), gibberellic acid (GA3), and indole acetic acid (IAA) in fruit juices, followed by HPLC-UV determination. The results showed that CV electropolymerization is significantly more efficient than the two other methods. The coatings created by the CV method were satisfactorily uniform, adhesive, and durable and exhibited higher extraction performance compared to the CP and CPP procedures. The important experimental variables of the proposed DI-SPME-HPLC method were evaluated and optimized using response surface methodology with a Box-Behnken design. The developed method showed wide-range linearities, spanning from 0.05 to 20μg mL−1 for GA3, and 0.02 to 20μg mL−1 for ABA and IAA. The limits of detection were obtained 0.01μg mL−1 for GA3, and 0.005μg mL−1 for ABA and IAA. The fiber was successfully employed for the simultaneous DI-SPME-HPLC analysis of plant hormones in fruit juice samples.

Vacuum-Assisted Headspace Solid-Phase Microextraction Sampling Method for the Extraction of Semi-Volatile Compounds: An Overview

Vacuum-assisted headspace solid-phase microextraction (Vac-HS-SPME) is an emerging sampling technique that enhances the extraction of semi-volatile compounds. The one extra step of pulling vacuum from the sampling vial pre-equilibrium increases the concentration of semi-volatiles in the headspace and allows for faster extraction times. This overview highlights the timeline, applications, and fundamentals of Vac-HS-SPME.

Analytical factors for eight short-chain fatty acid analyses in mouse feces through headspace solid-phase microextraction-triple quadrupole gas chromatography tandem mass spectrometry.

This study developed a method for quantifying eight short-chain fatty acids (SCFAs) in mouse fecal samples using solid-phase microextraction (SPME) coupled with triple quadrupole gas chromatography tandem mass spectrometry. Furthermore, significant factors affecting SCFA analysis, including SPME fiber selection, pH, salting-out agent, and sample collection time, were investigated. Contrary to previous studies, we found that the CAR/PDMS fiber had the highest extraction efficiency for all SCFAs. The optimal extraction efficiency was observed at pH 2.0, particularly for low-molecular-weight SCFAs. NaH2PO4 showed a more effective extraction efficiency than NaCl, owing to its pH stability and less interference with the solvent matrix. Additionally, our results showed that the SCFA concentration increased over collection time. The composition ratio of the eight SCFAs was maintained for up to 24h; thus, we concluded that samples should be collected within four hours to obtain reliable results. Our findings may improve laboratory methods for SCFA extraction and mouse fecal sample analysis.

Rapid on-site detection of underground petroleum pipeline leaks and risk assessment using portable gas chromatography-mass spectrometry and solid phase microextraction

Locating underground pipeline leaks can be challenging due to their hidden nature and variable terrain conditions. To sample soil gas, solid-phase microextraction (SPME) was employed, and a portable gas chromatography/mass spectrometry (GC/MS) was used to detect the presence and concentrations of petroleum hydrocarbon volatile organic compounds (pH-VOCs), including benzene, toluene, ethylbenzene, and xylene (BTEX). We optimized the extraction method through benchtop studies using SPME. The appropriate fibre materials and exposure time were selected for each BTEX compound. Before applying SPME, we preconditioned the soil vapour samples by keeping the temperature at around 4 °C and using ethanol as a desorbing agent and moisture filters to minimize the impact of moisture. To conduct this optimisation, airbags were applied to condition the soil vapour samples and SPME sampling. By conditioning the samples using this method, we were able to improve analytical efficiency and accuracy while minimizing environmental impacts, resulting in more reliable research data in the field. The study employed portable GC/MS data to assess the concentration distribution of BTEX in soil vapour samples obtained from 1.5 m below the ground surface at 10 subsurface vapour monitoring locations at the leak site. After optimization, the detection limits of BTEX were almost 100 µg/m3, and the measurement repeatabilities were approximately 5% and 15% for BTEX standards in the laboratory and soil vapour samples in the field, respectively. The soil vapour samples showed a hotspot region with high BTEX concentrations, reaching 30 mg/m3, indicating a diesel return pipeline leak caused by a gasket failure in a flange. The prompt detection of the leak source was critical in minimizing environmental impact and worker safety hazards.

Yeast Strain Influences the Hop-Derived Sensory Properties and Volatile Composition of Beer.

The perception of hop-derived flavour in beer is not well understood, particularly regarding the effect that different yeast strains and fermentation parameters have on perceived hop aroma and the mechanisms responsible for these changes. To evaluate the influence of yeast strain on the sensory properties and volatile composition of beer, a standard wort, late-hopped with New Zealand Motueka hops (5 g·L-1), was fermented with one of twelve yeast strains under constant conditions (temperature and yeast inoculation rate). The bottled beers were evaluated using a free sorting sensory methodology, and their volatile organic compounds (VOC) were assessed using gas chromatography mass spectrometry (GC/MS) with headspace solid-phase microextraction (SPME) sampling. Beer fermented with SafLager W-34/70 yeast was associated with a hoppy flavour attribute, whereas WY1272 and OTA79 beers were sulfury, and WY1272 was also metallic. WB06 and WLP730 beers were perceived to be spicy, with WB06 beer also perceived as estery, whereas VIN13 beer was sour, and the WLP001 beer was astringent. Beers fermented using the twelve yeast strains had clearly distinct VOC profiles. Beer made with WLP730, OTA29, SPH, and WB06 yeasts had the highest 4-vinylguaiacol levels, which contributed to their spicy attribute. Beer made with W3470 had high levels of nerol, geraniol, and citronellol, which supported its sensory characterisation as being 'hoppy'. This research has illustrated the important role that yeast strain has on modulating hop flavour in beer.

Incorporating performance reference compounds in retractable/reusable solid phase microextraction fiber for passive sampling of hydrophobic organic contaminants in water

Solid phase microextraction (SPME) has been used to measure aqueous-phase hydrophobic organic chemicals (HOCs) in equilibrium passive sampling mode for over two decades. However, determination of the extent of equilibrium has not been well-established for the retractable/reusable SPME sampler (RR-SPME), especially in the field applications. The goal of this study was to establish a method regarding to sampler preparation and data processing to characterize the extent of equilibrium of HOCs on the RR-SPME (100-μm thickness of polydimethylsiloxane (PDMS) coating) by incorporating performance reference compounds (PRCs). A fast (4 h) PRC loading protocol was identified with using a ternary solvent mixture (i.e., acetone-methanol-water mixture (4:4:2, v/v)) to accommodate diverse carrier solvents of the PRCs. The isotropy of the RR-SPME was validated by a paired, co-exposure approach with 12 different PRCs. The aging factors measured with the co-exposure method approximately equal to one, indicating the isotropic behavior was not changed after storage at 15 °C and −20 °C for 28 days. As a method demonstration, the PRC-loaded RR-SPME samplers were deployed in the ocean off Santa Barbara, CA (USA) for 35 days. The PRCs approaching the extents of equilibrium ranged from 20 ± 15.5 % to 96.5 ± 1.5 % and showed a declining trend along with log KOW increase. A generic equation relationship was deduced based on a correlation relationship of desorption rate constant (k2) and log KOW to extrapolate non-equilibrium correction factor from the PRCs to the HOCs. The merit of the present study is manifested by its theory and implement to enable the RR-SPME passive sampler to be utilized in environmental monitoring.

GC-MS/FID/EAD: A method for combining mass spectrometry with gas chromatography-electroantennographic detection

Gas chromatography-electroantennographic detection (GC-EAD), typically combined with a flame ionization detector (FID), is a widely used technique for studying insect semiochemicals. Combining mass spectrometry (MS) with GC-EAD is extremely beneficial, but has seldom been adopted, possibly due to the practical challenges associated with incorporating an MS (under vacuum) into a GC-EAD system. We describe a novel method of incorporating MS into a GC-EAD system, where the FID is maintained in the system rather than being replaced by an MS. With this method, effluent is still split between EAD and FID, with the FID being used to assign components that elicit antennal responses, as in a normal GC-FID/EAD system. The MS is introduced via a second effluent splitter inserted before the split between the EAD and the FID. This method allows for EAD, FID, and MS data to be obtained from a single injection, which is especially useful for analysis of thermally desorbed and solid-phase microextraction (SPME) samples. This configuration is also relatively simple to implement and resolves some of the practical challenges associated with dividing effluent between a detector at atmospheric pressure (a live antenna) and a detector under vacuum (the MS). We present test runs with hawkmoth antennae and floral volatiles to demonstrate the effectiveness of this system, and discuss the challenges and practical solutions to incorporating MS into a GC-EAD system that retains an FID detector.

At-Line Sampling and Characterization of Pyrolytic Vapors from Biomass Feedstock Blends Using SPME-GC/MS-PCA: Influence of Char on Fast Pyrolysis.

Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) analysis was used for the at-line sampling of pyrolytic vapors produced during the fast pyrolysis of biomass. The pure and binary blends of switchgrass (SWG) and pine harvest residues (PT6) were used as biomass feedstocks. Sequential SPME sampling allowed for monitoring of changes in the pyrolysis vapors as char accumulated in the fluid bed. The relative concentration and composition of the pyrolysis vapors desorbed from the SPME fibers were investigated using GC-MS, and the resulting chromatograms were analyzed using principal component analysis (PCA) to compare the composition of the pyrolysis vapors over the course of the pyrolysis run. The chemical compositions of both carbohydrate and lignin fragments varied as the char builds up in the reactor bed. Fragments derived from cellulose and hemicelluloses included anhydrosugars, furans, and light-oxygenated compounds. Lignin fragments included methoxyphenols, phenolic ketones, aldehydes, and low-molecular-weight aromatics. The composition of the carbohydrate fragments changed more than those of the lignin fragments as the char built up in the fluid bed. This combination of SPME-GC/MS-PCA was a novel, easy, and effective method for measuring the composition and changes in the composition of pyrolysis vapors during the fast pyrolysis process. This work also highlighted the effect of char build-up on the composition of the overall pyrolysis vapors.

Detection of bile acids in small volume human bile samples via an amino metal-organic framework composite based solid-phase microextraction probe

In recent years, bile acids (BAs), the important component of bile, were found closely related to the occurrence and development of diseases, therefore, determination of BAs in bile samples is of great significance. However, biological matrix complexity and low concentrations of BAs were still challenging for BA detection in small amount of bile samples. In this work, a core-shell NH2-MIL101@mSiO2 was designed to improve the capture ability of BAs in biological samples, as well as possess good biocompatibility. Subsequently, solid-phase microextraction (SPME) probe of the NH2-MIL101@mSiO2 was coupled with HPLC-MS/MS to establish the analysis method for detecting eight BAs in bile samples. The established method received extraction efficiencies of (30–2143)-fold higher than those of the commercial probes and low limit of detection (LOD ≤ 0.21 ng mL−1). The miniaturization of SPME sampling devices, as well as the low LOD of this work, endowed this method advantage of low consumption of bile samples (30 μL). Based on the proposed method, eight BAs in bile samples of pancreatic cancer patients and cholelithiasis patients were detected successfully. A distinct difference was found in the concentrations of four targeted BAs in bile samples from pancreatic cancer patients and cholelithiasis patients. This work provided a method for quantification of eight BAs in small volume human bile samples, and it could open up a perspective regarding the relationship between BA metabolism and the occurrence of diseases.

Dynamic Metabolic Changes During Prolonged Ex Situ Heart Perfusion Are Associated With Myocardial Functional Decline.

Ex situ heart perfusion (ESHP) was developed to preserve and evaluate donated hearts in a perfused beating state. However, myocardial function declines during ESHP, which limits the duration of perfusion and the potential to expand the donor pool. In this research, we combine a novel, minimally-invasive sampling approach with comparative global metabolite profiling to evaluate changes in the metabolomic patterns associated with declines in myocardial function during ESHP. Biocompatible solid-phase microextraction (SPME) microprobes serving as chemical biopsy were used to sample heart tissue and perfusate in a translational porcine ESHP model and a small cohort of clinical cases. In addition, six core-needle biopsies of the left ventricular wall were collected to compare the performance of our SPME sampling method against that of traditional tissue-collection. Our state-of-the-art metabolomics platform allowed us to identify a large number of significantly altered metabolites and lipid species that presented comparable profile of alterations to conventional biopsies. However, significant discrepancies in the pool of identified analytes using two sampling methods (SPME vs. biopsy) were also identified concerning mainly compounds susceptible to dynamic biotransformation and most likely being a result of low-invasive nature of SPME. Overall, our results revealed striking metabolic alterations during prolonged 8h-ESHP associated with uncontrolled inflammation not counterbalanced by resolution, endothelial injury, accelerated mitochondrial oxidative stress, the disruption of mitochondrial bioenergetics, and the accumulation of harmful lipid species. In conclusion, the combination of perfusion parameters and metabolomics can uncover various mechanisms of organ injury and recovery, which can help differentiate between donor hearts that are transplantable from those that should be discarded.

Metabolomic fingerprinting of porcine lung tissue during pre-clinical prolonged ex vivo lung perfusion using in vivo SPME coupled with LC-HRMS

Normothermic ex vivo lung perfusion (NEVLP) has emerged as a modernized organ preservation technique that allows for detailed assessment of donor lung function prior to transplantation. The main goal of this study was to identify potential biomarkers of lung function and/or injury during a prolonged (19 h) NEVLP procedure using in vivo solid-phase microextraction (SPME) technology followed by liquid chromatography-high resolution mass spectrometry (LC-HRMS). The use of minimally invasive in vivo SPME fibers for repeated sampling of biological tissue permits the monitoring and evaluation of biochemical changes and alterations in the metabolomic profile of the lung. These in vivo SPME fibers were directly introduced into the lung and were also used to extract metabolites (on-site SPME) from fresh perfusate samples collected alongside lung samplings. A subsequent goal of the study was to assess the feasibility of SPME as an in vivo method in metabolomics studies, in comparison to the traditional in-lab metabolomics workflow. Several upregulated biochemical pathways involved in pro- and anti-inflammatory responses, as well as lipid metabolism, were observed during extended lung perfusion, especially between the 11th and 12th hours of the procedure, in both lung and perfusate samples. However, several unstable and/or short-lived metabolites, such as neuroprostanes, have been extracted from lung tissue in vivo using SPME fibers. On-site monitoring of the metabolomic profiles of both lung tissues through in vivo SPME and perfusate samples on site throughout the prolonged NEVLP procedure can be effectively performed using in vivo SPME technology.

Cinnamyl alcohol: An attractant of the flower thrips Frankliniella intonsa

Catches of Frankliniella intonsa females (A) and males (B) in traps baited with five floral compounds (10 mg each) in red pepper fields • The flower thrips Frankliniella intonsa are attracted to highbush blueberry flowers. • Cinnamyl alcohol was the major component of floral volatiles of highbush blueberry. • Cinnamyl alcohol significantly attracted adult F. intonsa in the field. • The minor floral compounds had no additive activity with cinnamyl alcohol alone. Flower-inhabiting thrips find hosts using olfactory and visual cues. In this study, we report the identification of a plant-produced attractant of the flower thrips Frankliniella intonsa (Trybom), an important agricultural pest worldwide. GC–MS analysis of solid-phase microextraction samples from blueberry flowers, Vaccinium corymbosum L., that mediate the attraction of adult F. intonsa revealed that the major component was cinnamyl alcohol, followed by cinnamyl acetate, cinnamaldehyde, germacrene D, β -bourbonene, β -caryophyllene, and benzyl benzoate. The biological activity of the floral compounds was investigated using commercial cinnamaldehyde, cinnamyl alcohol, β -caryophyllene, cinnamyl acetate, and benzyl benzoate in hot pepper ( Capsicum annuum L.) fields. Significantly more F. intonsa males and females were caught in red delta traps with cinnamyl alcohol than in all other traps. Cinnamaldehyde and cinnamyl acetate attracted adult F. intonsa but were not as attractive as cinnamyl alcohol. β -Caryophyllene and benzyl benzoate were not attractive. Furthermore, the addition of four minor components to cinnamyl alcohol did not result in increased trap catches relative to cinnamyl alcohol alone, indicating that cinnamyl alcohol is responsible for attracting adult F. intonsa toward blueberry flowers. Therefore, this phenylpropanoid could be used as an effective lure for monitoring and controlling F. intonsa .

Characteristics of Tris(chloropropyl)phosphate (TCPP) emission from upholstered furniture in offices and consequence on indoor air quality

Tris (chloropropyl)phosphate (TCPP) is a flame retardant currently used in upholstered furniture. This study provides the results of a follow up of TCPP concentrations in indoor air and at the surface of indoor materials in two offices after introduction of fireproof upholstered furniture (cushions made of PU foam containing TCPP). An emission cell coupled to solid-phase microextraction sampling was used as measurement means for direct measurement of gaseous TCPP concentration at the surface of the source material. Indoor TCPP concentrations reached high levels from 400 to 880 ng m−3 in correlation with gaseous concentrations measured at the surface of source materials (cushions) ranging from 5.5 to 17.7 μg m−3. The changes in these concentrations showed no decline over more than 220 days and were mainly explained by temperature influence on emission. By applying the Clausius-Clapeyron equation, it was shown that the emission is close to vaporization of pure liquid TCPP. A model taking into account only the processes of emission/diffusion of compound in air and its removal by ventilation provided an acceptable prediction. Exposure by inhalation of occupants to TCPP in two offices were assessed to be 2933 ng.day−1 (with median level) and 4692 ng.day−1 (with maximum level).

Nitrocellulose blister material as a source of N-nitrosamine contamination of pharmaceutical drug products

The recent focus of pharmaceutical regulatory authorities has been oriented towards the mitigation of carcinogenic N-nitrosamines in drug products and different sources of N-nitrosamines have been revealed. Within this work, the elucidation of a further source of N-nitrosamines in drug products is reported. A case was investigated where traces of N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were detected in a finished dosage form, whereas they were not found in the bulk drug product. This led to an in-depth study of blister material as a potential source, wherein nitrocellulose primer in a lidding foil was identified as a risk factor. Nitrocellulose acts as a nitrosating agent for secondary amines, present in printing inks, forming N-nitrosamines in lidding foil. Their formation was confirmed by the addition of printing ink containing dimethylamine and diethylamine, or diethylamine alone, to lidding foil containing nitrocellulose primer. Their transfer to drug product during the blistering operation was demonstrated by solid-phase microextraction sampling of N-nitrosamine vapors on two commonly used types of pharmaceutical blistering machines, operating with plate sealing or roller sealing technology. Higher vapor amounts were detected on plate sealing equipment, where N-nitrosamine contamination was additionally confirmed in film-coated tablets and blister cavities of the finished dosage form.

Comparison of the molecular properties and volatile compounds of Maillard reaction products derived from animal- and cereal-based protein hydrolysates

The changes in the molecular properties and volatile compounds of Maillard reaction products obtained from chicken bone extract (CBE), wheat protein (WP), and rice protein (RP) hydrolysates were compared in this study. Pressure cooking was used to prepare CBE, which was then filtered, defatted, and concentrated. The optimum enzyme-substrate (E/S) ratio of CBE, WP, and RP on Flavourzyme® using the Michaelis-Menten model was 4.0, 5.7, 4.8% w/w, respectively. The occurrence of the Maillard reaction was demonstrated by the lowering of pH, low molecular weight peptides (<1K Da), and total free amino acids after the samples were heat-treated. Volatile compounds were analysed using gas chromatography-mass spectrometry (GC–MS) in conjunction with headspace solid-phase microextraction (SPME) sampling. Pyrazines, furan, and thioethers were detected in the MRPs of CBE, WP and RP. It was concluded that the MRPs of CBE, WP, and RP could be used as potential natural flavours in food applications.

Chemical volatile composition and phytotoxic potential of Daphne gnidium L. leaves

Daphne gnidium L. (Thymelaeaceae) is an evergreen shrub from the Mediterranean area traditionally used for its medicinal and non-medicinal properties. Several studies showed its adverse impact on different targets including malignant cells, microbes, radicals, insects. The negative interactions between D. gnidium and other plant species have been rather neglected so far, as well as its chemical volatile composition. Therefore, this work aimed to assess the phytotoxic activity of D. gnidium on filter paper and soil in pre-emergence conditions by testing both the aqueous extract (10–100%) and the powder (0.25–1 g) obtained from the leaves as bioagrochemicals. The results showed that D. gnidium was able to significantly decrease seed germination and growth parameters of the receiver plants with different effectiveness (p-values < 0.05). Overall, Sinapis alba L. (Brassicaceae) was the most susceptible species followed by Lolium multiflorum Lam. (Poaceae) and Trifolium incarnatum L. (Fabaceae) while aqueous extract was more active than the powder. Solid-Phase Microextraction (SPME) sampling technique and Gas Chromatograph/Mass spectrometer (GC/MS) analyses were used to characterize the volatile fraction highlighting considerable differences in the composition of the analyzed samples. Hexahydrofarnesyl acetone (29.7%) followed by 3,7,11,15-tetramethyl-2-hexadecen-1-ol (28.3%) and β-damascenone (32.0%) followed by eudesma-1,4(15), 11-triene (27.1%) were detected as main volatile compounds of the powder and the aqueous extract, respectively.