Photometric Detection Research Articles

Identification of key odorants in traditional Shaoxing-jiu and evaluation of their impacts on sensory descriptors by using sensory-directed flavor analysis approaches

To determine the key odorants of a popular Chinses rice wine, Shaoxing-jiu, volatile compounds were analyzed by using sensory-directed flavor approaches, including gas chromatography-mass spectrometry (GC-MS), gas chromatography-flame photometric detector (FPD), gas chromatography olfactometry (GC-O), aroma recombination and omission experiments, and odorant addition experiments. Fifty-five volatile compounds were detected in traditional Shaoxing-jiu via GC-MS, more than those in mechanical Shaoxing-jiu. Thirty-four aroma-active compounds in traditional Shaoxing-jiu were determined via GC-O. According to aroma recombination and omission experiments, the aroma profile of the recombination model constructed by these aroma-active compounds at their detected concentrations was similar to that of traditional Shaoxing-jiu, and 15 of them were affirmed as key odorants. Among the key odorants, phenylethyl alcohol, furfural, γ-nonalactone and dimethyl trisulfide presented very highly significant aroma contributions, indicating that their omission would cause great aroma differences. Then odorant addition experiments highlighted the aroma impacts of these four paramount key odorants on sensory descriptors in traditional Shaoxing-jiu.

Ecological and Human Health Risk Assessment of Pesticide Residues in Fish and Sediments from Vea Irrigation Reservoir

The low yield of food production ascribed to harm caused by pests has led to the application of pesticides to food crops. Pesticide residues from the application on crops are mostly found in foods that can cause diseases for consumers of such products. A total of 37 pesticide residues consisting of 15 organochlorines (OC), 13 organophosphorus (OP) and 9 synthetic pyrethroids (SP) were determined. The QuEChERS method was exploited for extraction and clean-up. Gas Chromatograph was used for detection and quantification which was equipped with an electron capture detector and pulse flame photometric detector. The results showed that the mean concentrations of pesticides in fish ranged from 0.007 mg·kg-1 to 1.026 mg·kg-1 for OCs, 0.002 mg·kg-1 to 0.190 mg·kg-1 for OPs and 0.004 mg·kg-1 to 0.032 mg·kg-1 for SP. Sediments have mean concentrations ranged from 0.005 mg·kg-1 to 1.207 mg·kg-1 for OCs. OP ranges from 0.002 mg·kg-1 to 0.399 mg·kg-1 and 0.003 mg·kg-1 to 0.202 mg·kg-1 for synthetic pyrethroids. Maximum Residue Limits were exceeded in both fish and sediment samples except for malathion, fenitrothion, profenofos, gamma-chlordane, and deltamethrin. Exposure in children ranged from 4.60 × 10-6 mg·kg-1·d-1 to 2.36 × 10-3 mg·kg-1·d-1 and in adults it is from 1.97 × 10-6 mg·kg-1·d-1 to 1.01 × 10-3 mg·kg-1·d-1. Health risk estimation revealed a non-cancer risk potential of β-HCH in sediment and aldrin and p,p'-DDE in fish. Carcinogenic risk assessed for organochlorine pesticide residues indicates cancer benchmark concentrations greater than 10-4 to 10-6 threshold for acceptance.

New Horizons Observations of the Cosmic Optical Background

Abstract We used existing data from the New Horizons Long-range Reconnaissance Imager (LORRI) to measure the optical-band (0.4 ≲ λ ≲ 0.9 μm) sky brightness within seven high–Galactic latitude fields. The average raw level measured while New Horizons was 42–45 au from the Sun is 33.2 ± 0.5 nW m−2 sr−1. This is ∼10× as dark as the darkest sky accessible to the Hubble Space Telescope, highlighting the utility of New Horizons for detecting the cosmic optical background (COB). Isolating the COB contribution to the raw total required subtracting scattered light from bright stars and galaxies, faint stars below the photometric detection limit within the fields, and diffuse Milky Way light scattered by infrared cirrus. We removed newly identified residual zodiacal light from the IRIS 100 μm all-sky maps to generate two different estimates for the diffuse Galactic light. Using these yielded a highly significant detection of the COB in the range 15.9 ± 4.2 (1.8 stat., 3.7 sys.) nW m−2 sr−1 to 18.7 ± 3.8 (1.8 stat., 3.3 sys.) nW m−2 sr−1 at the LORRI pivot wavelength of 0.608 μm. Subtraction of the integrated light of galaxies fainter than the photometric detection limit from the total COB level left a diffuse flux component of unknown origin in the range 8.8 ± 4.9 (1.8 stat., 4.5 sys.) nW m−2 sr−1 to 11.9 ± 4.6 (1.8 stat., 4.2 sys.) nW m−2 sr−1. Explaining it with undetected galaxies requires the assumption that the galaxy count faint-end slope steepens markedly at V > 24 or that existing surveys are missing half the galaxies with V < 30.

Determination of low environmental free cyanide concentrations in freshwaters

Cyanide compounds are naturally emitted into the environment in low levels by degradation processes or emitted from anthropogenic sources. In surface water, complex cyanide compounds as well as “free cyanide” are present. The latter term covers hydrogen cyanide and cyanide compounds which easily liberate hydrogen cyanide under slightly acidic conditions. Especially free cyanide may cause adverse effects in the environment. To exclude negative impacts on freshwater systems, in the context of the European Water Framework Directive (WFD), preventive regulatory activities for free cyanide are currently under discussion. However, established analytical methods for quantification of free cyanide only obtain limits of quantification (LOQs) in the range of 1 μg L−1. Thus, these methods are not sufficiently sensitive for a potential environmental quality standard (EQS) compliance monitoring at water concentrations below the current predicted no effect concentration (PNEC) level of free cyanide. In the present study, a standardized continuous flow analysis (CFA) method for quantification of low free cyanide concentrations was adapted by applying a special system which allows an ultra-sensitive photometric detection of a colored cyanide derivative. By this means, LOQs in a range of one magnitude below the PNEC are achievable. The method was validated according to ISO/IEC 17025 requirements. Free cyanide concentrations in tested surface water samples from a small river and a barrier lake with low anthropogenic influences were very low and clearly below the PNEC. The results prove that the adapted CFA method is suitable for the analysis of low concentration free cyanide in freshwaters and appropriate for a possible EQS compliance monitoring.

Determination of Carminic Acid in Foodstuffs and Pharmaceuticals by Microchip Electrophoresis with Photometric Detection

This paper presents a novel miniaturized analytical method for the determination of carminic acid, a natural red food dye, in complex food and pharmaceutical matrices by microchip electrophoresis (MCE) with photometric detection. MCE has become a very attractive microscale separation technique because it offers high-speed, high-throughput, small sample injection volume and low reagents consumption. Fast determination of carminic acid in less than 5 min was achieved on a poly(methyl methacrylate) microchip in anionic separation mode at pH 6. Photometric detector based on light-emitting diode technology was set to a wavelength of 490 nm. Using a sample injection volume of 900 nL, a limit of detection of 69 nmol L−1 was achieved. A wide linear dynamic range over four orders of magnitude (from nmol L−1 to mmol L−1) was observed for peak area. Developed method provided favorable intra- and inter-day repeatability of the migration time (up to 2.5% RSD), as well as the repeatability of the peak area (less than 1.9% RSD), regardless of the sample type. The content of carminic acid was determined in various foodstuffs and pharmaceuticals, such as candies, saffron, non-alcoholic drink, and sore throat lozenges with good recoveries (92.5–104.0%).

Separation and quantification of 2-keto-3-deoxy-gluconate (KDG) a major metabolite in pectin and alginate degradation pathways

A rapid and sensitive High Performance Liquid Chromatography (HPLC) method with photometric and fluorescence detection is developed for routine analysis of 2-Keto-3-deoxy-gluconate (KDG), a catabolite product of pectin and alginate. These polysaccharides are primary-based compounds for biofuel production and for generation of high-value-added products. HPLC is performed, after derivatization of the 2-oxo-acid groups of the metabolite with o-phenylenediamine (oPD), using a linear gradient of trifluoroacetic acid and acetonitrile. Quantification is accomplished with an internal standard method. The gradient is optimized to distinguish KDG from its close structural analogues such as 5-keto-4-deoxyuronate (DKI) and 2,5-diketo-3-deoxygluconate (DKII). The proposed method is simple, highly sensitive and accurate for time course analysis of pectin or alginate degradation.

Doppler Boosting of the S-stars in the Galactic Center

Abstract Astrometry and spectroscopy of the S-stars in the Galactic Center provide a unique way to probe the properties of the central supermassive black hole, as well as the post-Newtonian effects caused by its gravity, e.g., gravitational redshift and general relativistic precession. It has also been suggested that the photometry of S-stars can be used for studying the properties of the gaseous environment of Sgr A*. Due to the high velocities of the S-stars, sometimes approaching 0.1c, their photometric signal should be considerably affected by the Doppler boosting. We calculate this relativistic effect for several S-stars closely approaching the central black hole (most of them recently announced) and show that the amplitude of the photometric variability due to the Doppler boosting for some of them (S62 and S4714) exceeds 6%; for the well-studied star S2 it is about 2%. Measurement of the Doppler boosting can confirm the existence and help refine orbital parameters of the S-stars with noisy spectroscopy and astrometry. This effect should be explicitly accounted for when the photometry of S-stars is used for probing the medium around the Sgr A*. We discuss the observability of the Doppler boosting given the complications typical for the Galactic Center and conclude, in particular, that the purely photometric detection of the higher-order relativistic corrections to the Doppler-boosting signal (due to the gravitational redshift and transverse Doppler shift, which we also calculate) is hardly possible for the S-stars.

Chemical changes in thirdhand smoke associated with remediation using an ozone generator

Ozonation is a common remediation approach to eliminate odors from mold, tobacco and fire damage in buildings. Little information exists to: 1) assess its effectiveness; 2) provide guidance on operation conditions; and 3) identify potential risks associated with the presence of indoor ozone and ozonation byproducts. The goal of this study is to evaluate chemical changes in thirdhand smoke (THS) aerosols induced by high levels of ozone, in comparison with THS aerosols aged under similar conditions in the absence of ozone. Samples representing different stages of smoke aging in the absence of ozone, including freshly emitted secondhand smoke (SHS) and THS, were collected inside an 18-m3 room-sized chamber over a period of 42 h after six cigarettes were consumed. The experiments involved collection and analysis of gas phase species including volatile organic compounds (VOCs), volatile carbonyls, semivolatile organic compounds (SVOCs), and particulate matter. VOC analysis was carried out by gas chromatography/mass spectrometry with a thermal desorption inlet (TD-GC/MS), and volatile carbonyls were analyzed by on-line derivatization with dinitrophenylhydrazine (DNPH), followed by liquid chromatography with UV/VIS detection. SVOCs were extracted from XAD-coated denuders and Teflon-coated fiberglass filters in the absence of ozone. In those extracts, tobacco-specific nitrosamines (TSNAs) and other SVOCs were analyzed by gas chromatography with positive chemical ionization-triple quadrupole mass spectrometric detection (GC/PCI-QQQ-MS), and polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography with ion trap mass spectrometric detection (GC/IT-MS) in selected ion monitoring mode. Particulate matter concentration was determined gravimetrically. In a second experiment, a 300 mg h−1 commercial ozone generator was operated during 1 h, one day after smoke was generated, to evaluate the remediation of THS by ozonation. VOCs and volatile carbonyls were analyzed before and after ozonation. Extracts from fabrics that were exposed in the chamber before and after ozonation as surrogates for indoor furnishings were analyzed by GC/IT-MS, and aerosol size distribution was studied with a scanning mobility particle sizer. Ozone concentration was measured with a photometric detector. An estimated 175 mg ozone reacted with THS after 1 h of treatment, corresponding to 58% of the total O3 released during that period. Fabric-bound nicotine was depleted after ozonation, and the surface concentration of PAHs adsorbed to fabric specimens decreased by an order of magnitude due to reaction with ozone, reaching pre-smoking levels. These results suggest that ozonation has the potential to remove harmful THS chemicals from indoor surfaces. However, gas phase concentrations of volatile carbonyls, including formaldehyde, acetaldehyde and acetone were higher immediately after ozonation. Ultrafine particles (UFP, in most cases with size <60 nm) were a major ozonation byproduct. UFP number concentrations peaked shortly after ozonation ended, and remained at higher-than background levels for several hours. Based on these results, minimum re-entry times after ozone treatment were predicted for different indoor scenarios. Clearly defining re-entry times can serve as a practical measure to prevent acute exposures to ozone and harmful ozonation byproducts after treatment. This study evaluated potential benefits and risks associated with THS remediation using ozone, providing insights into this technology.

N,N-Dichlorobenzyl amine: An effective decontaminant for highly toxic chemical warfare agents sulfur mustard and VX

The chemical decontamination of vesicant, bis(2-chloroethyl)sulfide (Sulfur Mustard, SM) and nerve agent O-ethyl S-2-(N,N-diisopropylaminoethyl) methylphosphonothiolate (VX) has been achieved by an operationally simple method by using a new positive chlorine bearing reagent N,N-dichlorobenzylamine. Deactivation of these highly toxic chemical warfare agents has been achieved in acetonitrile-water medium. Before attempting the reactions on these highly toxic real agents, the reagent has been successfully tested for its decontaminating efficiency on the non-toxic simulants (2-chloroethyl phenyl sulfide, a simulant of Sulfur Mustard and O,S-diethyl methylphosphonothioate, simulant of VX). Progress of the decontamination reactions have been monitored by gas chromatography coupled with a flame photometric detector working in sulfur detection mode (GC-FPD(S)), 1H and 31P{1H} NMR spectroscopy. The products obtained after decontamination of Sulfur Mustard (SM) and VX have been thereafter identified by GC-MS technique. This reagent has been found to be highly advantageous over earlier reported decontaminating reagents in terms of - ease of preparation, cost effectiveness, stability, good shelf life and instantaneous conversion of both SM and VX into nontoxic products at room temperature.

Measurement Device for Ambient Carbonyl Sulfide by Means of Catalytic Reduction Followed by Wet Scrubbing/Fluorescence Detection.

A portable chemical analysis system for monitoring ambient carbonyl sulfide (COS) was investigated for the first time. COS is paid attention to from the perspectives of photosynthesis tracer, breath diagnosis marker, and new process-use in the manufacture of semiconductors. Recently, the threshold level value of COS was settled at 5 ppm in volume ratio (ppmv) for workplace safety management. In this work, COS was converted to H2S by a small column packed with alumina catalyzer at 65 °C. Then, the H2S produced was collected in a small channel scrubber to react with fluorescein mercuric acetate (FMA), and the resulting fluorescence quenching was monitored using an LED/photodiode-based miniature detector. The miniature channel scrubber was re-examined to determine its robustness and easy fabrication, and conditions of the catalyzer were optimized. When the FMA concentration used was 1 μM, the limit of detection and dynamic range, which were both proportional to the FMA concentration, were 0.07 and 25 ppbv, respectively. Ambient COS in the background level and even contaminated COS in the nitrogen gas cylinder could be detected. If necessary, H2S was removed selectively by reproducible adsorbent columns. COS concentrations of engine exhaust were measured by the proposed method and by cryo-trap-gas chromatography-flame photometric detection, and the results obtained (0.5–5.9 ppbv) by the two methods agreed well (R2 = 0.945, n = 19). COS in ambient air and exhaust gases was successfully measured without any batchwise pretreatment.

Characterization of the key aroma compounds in Laoshan green teas by application of odour activity value (OAV), gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-qMS)

To investigate the key aroma compounds in Laoshan green teas (Huangshan (S1), Changling (S2), and Fangling (S3)), gas chromatography-mass spectrometry-olfactometry (GC-MS-O), a flame photometric detector (FPD), odor activity value (OAV), and comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-qMS) were employed. A total of 50 aroma compounds were perceived and 24 compounds were identified as important compounds related to OAV, such as dimethyl sulfide (OAV: 126–146), skatole (OAV: 27–50), furaneol (OAV: 8–27), (Z)-jasmone (OAV: 16–23), 2-methylbutanal (OAV: 15–22), and 3-methylbutanal (OAV: 68–87). Furthermore, the S-curve method was used to research the effect of aroma compounds on the threshold of aroma recombination (AR). The AR thresholds decreased from 3.8 mL to 0.45, 0.66, 0.93, 0.95, 0.75, 1.09, 3.01, and 2.57 mL after addition of eight compounds (skatole, furaneol, (Z)-jasmone, α-damascenone, sclareololide, dihydroactinidiolide, vanillin, and δ-valerolactone), indicating that those compounds (OAV >1) were contributors to the overall aroma of Laoshan teas.

Real-time air pollution (PM2.5) measurements in Education City, Doha, Qatar: Evaluating data from two different photometric monitors

Background: Given the health hazards posed by particulate matter 2.5 (PM2.5), the need exists for simple, cost-effective, and real-time methods to monitor air quality with high spatio-temporal resolution. Direct-reading photometric detection is one modality of real-time PM2.5 monitoring. However, photometric data often require post hoc correction factors specific to individual manufacturers, meteorological conditions, and particle sizes and compositions. Methods: We methodically compared and evaluated PM2.5 concentration values collected by two different photometric monitors (TSI Environmental Monitor 8540 and MetOne ES-642) in Education City, Doha, Qatar. We analyzed the data collected by the two monitors in two different locations in September and December 2019, and side-by-side for two weeks in February 2020. Correlation and linear regression analyses were conducted to determine correction factors between the two monitors. Results and Discussion: The results indicate that both monitors reported almost identical trends in PM2.5 concentration, while the TSI monitor exaggerated the values by approximately twofold. When correlation-based corrections were applied, data from the two monitors matched almost perfectly for all comparison periods. As correction factors between PM2.5 sensors may vary based on in situ conditions, calibration must therefore be conducted on a case-by-case basis. However, our methodologies could constitute a template for future development of cross-calibration strategies. In addition, we determined average PM2.5 concentrations in Education City for each study period. These values were lower than those previously reported for other locations in Qatar during similar seasons. Conclusions: Our findings emphasize the relevance of the microenvironment when assessing PM2.5 levels for public health purposes. This investigation is expected to support and inform air quality management and mitigation strategies.

Method development for the determination of Synthetic Musks and Organophosphorus Pesticides in Human Adipose Tissue

Synthetic musks and organophosphorus pesticides represent a potential risk to the human health since exposure can lead to distinct types of carcinogenesis and endocrine disorders. These are lipophilic compounds as such, prone to deposit and persist in fat tissues, mainly in adipose tissue. Very few studies have reported on the occurrence and accumulation profile of these contaminants in human adipose tissue.Analytical methods for the detection and quantification of synthetic musks and organophosphorus pesticides in adipose tissue are lacking. In this study, the efficacy of different extraction with ultrasonic homogenizer and dispersive solid-phase extraction (d-SPE) clean-up methods were evaluated in human adipose tissue. The relative sample clean-up was assessed by measurement of total lipid content. The quantification of four synthetic musks and six organophosphorus pesticides were performed by gas chromatography (GC) mass spectrometry (MS) and flame photometric detection (FPD), respectively.The d-SPE clean-up with 50 mg PSA, 150 mg MgSO4, 100 mg C18EC and 50 mg Z-Sep provided the most effective clean-up, removing the greatest amount of interfering substances including lipids and simultaneously ensuring good chromatographic separation and recoveries. Method detection limits were between 4 to 9 ng/g for synthetic musk and 1 to 7 ng/g for organophosphorus pesticides in adipose tissue. The proposed method was applied to adipose tissue of obese patients and positive samples were confirmed with GC tandem mass spectrometry. Galaxolide was found in all the samples tested with concentrations ranging from 0.08 to 0.5 μg/g of adipose tissue. No other synthetic musk studied was detected. Organophosphorus pesticides were not found in the analysed samples.The developed analytical procedures were successful and can easily be applied to biomonitoring these compounds in human adipose tissue.

The application of pharmaceutical quality by design concepts to evaluate the antioxidant and antimicrobial properties of a preservative system including desferrioxamine.

The purpose of the present study was to investigate the antioxidant and antimicrobial activities of a conventional preservative system containing desferrioxamine mesylate (DFO) and optimize the composition of the system through mathematical models. Different combinations of ethylenediaminetetraacetic acid (EDTA), sodium metabisulfite (SM), DFO and methylparaben (MP) were prepared using factorial design of experiments. The systems were added to ascorbic acid (AA) solution and the AA content over time, at room temperature and at 40°C was determined by volumetric assay. The systems were also evaluated for antioxidant activity by a fluorescence-based assay. Antimicrobial activity was assessed by microdilution technique and photometric detection against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Aspergillus brasiliensis. A multi-criteria decision approach was adopted to optimize all responses by desirability functions. DFO did not extend the stability of AA over time, but displayed a better ability than EDTA to block the pro-oxidant activity of iron. DFO had a positive interaction with MP in microbial growth inhibition. The mathematical models showed adequate capacity to predict the responses. Statistical optimization aiming to meet the quality specifications of the ascorbic acid solution indicated that the presence of DFO in the composition allows to decrease the concentrations of EDTA, SM and MP. DFO was much more effective than EDTA in preventing iron-catalyzed oxidation. In addition, DFO improved the inhibitory response of most microorganisms tested. The Quality by Design concepts aided in predicting an optimized preservative system with reduced levels of conventional antioxidants and preservatives, suggesting DFO as a candidate for multifunctional excipient.

On-site analysis of paraquat using a completely portable photometric detector operated with small, rechargeable batteries

This work describes a methodology that can be used to achieve on-site analysis of paraquat in water samples by using a miniaturized portable photometer consisting of a couple of light-emitting diodes (LEDs). Paraquat produces a colored radical via a redox reaction with sodium dithionite, which is unstable against oxygen in solution. The steps taken to stabilize the reagent solution included control of the pH and the addition of organic solvents, but the most effective was the formation of an oil layer. Together, these steps stabilized the reagent solution for two days. An increase in the duration of reagent stability, however, is necessary in order to transport the reagent for on-site applications in remote locales. For the time being, an excess amount of solid sodium dithionite can be added directly to sample solutions because the unreacted dithionite shows no influence on absorbance of the paraquat radical. Orange LEDs with a maximum emission wavelength of 609 nm were employed in the portable photometer to measure the absorbance of paraquat radical produced by a redox reaction that has an absorption maximum of 603 nm. The developed photometer showed excellent performance with a linear range of from 2.0 mg L−1 to 40.0 mg L−1 and a linear regression (r2 = 1). The limits of detection and quantification were 0.5 mg L−1 and 1.5 mg L−1, respectively, intra-day precision (n = 3) and inter-day precision (n = 5) were both less than 5%, and accuracy based on the percentage of sample recovery ranged from 89 ± 0 to 105 ± 0% (n = 3). The proposed method was applied to the analysis of paraquat in water samples taken from rice fields. The results showed no paraquat in all thirteen samples, which could have been due to strong adsorption of paraquat by soil particles and/or to complications with the sampling conditions. To confirm the adsorption onto soil of paraquat contained in water, we constructed an artificial rice field where water containing paraquat was impounded above the soil layer. The results showed that paraquat in water gradually decreased within three days and could be measured in the soil on the fourth day. These results were confirmed by HPLC analysis, which underscores the utility of this portable photometer for the on-site monitoring of paraquat in water samples.

Characterization of aroma-active compounds and perceptual interaction between esters and sulfur compounds in Xi baijiu

The aroma-active compounds of three Xi baijiu samples (Xijiulan, Y1, Xijiuyinxiangguizhou, Y2 and Xijiuyinzhi, Y3) were analyzed by gas chromatography–olfactometry (GC–O), GC–flame photometric detection (FPD) and odor activity value (OAV). The results indicated that a total of 92 aroma compounds were determined, including 16 sulfur compounds. Furthermore, 2-methyl-3-furanthiol (OAV: 31–220), 3-mercapohexyl acetate (OAV: 1870), dimethyl trisulfide (OAV: 333–400), 3-mercaptohexanol (OAV: 34–36), β-damascenone (OAV: 1317–1342), 2-butylfuran (OAV: 629–672), ethyl 3-methylbutanoate (OAV: 655–899), ethyl hexanoate (OAV: 687–729), and ethyl octanoate (OAV: 1164–1362) exhibited much higher OAVs and aroma intensities (AIs) than other compounds. Finally, the perceptual interactions between five sulfur compounds and six esters were studied using Feller’s additive model in Y2. Among the 30 binary mixtures, 12 groups showed an additive effect, 4 groups exhibited a synergistic effect, and 14 groups exerted a masking effect. These data indicated that dimethyl disulfide and 2-methyl-3-furanthiol had masking and additive effects on the aroma of esters.

Molecularly imprinted polymers immobilized on graphene oxide film for monolithic fiber solid phase microextraction and ultrasensitive determination of triphenyl phosphate

Triphenyl phosphate (TPhP), a typical model of organophosphorus flame retardants (OPFRs), has been regarded as emerging environmental contaminants of health concern. In this study, TPhP molecularly imprinted polymers immobilized on graphene oxide (GO) film (TPhP-MIPs/GO) monolithic fiber for direct immersion solid phase microextraction (DI-SPME) was fabricated and evaluated. Compared with TPhP molecularly imprinted polymers (TPhP-MIPs) monolithic fiber, TPhP-MIPs/GO fiber had bigger extraction capacity, stronger hydrophilicity and faster mass transfer rate. Furthermore, TPhP-MIPs/GO fiber displayed excellent selectivity for TPhP among its structure analogues. It was thermally stable up to 320 °C so that it can withstand the high temperature of gas chromatography (GC) injection port for desorption and detection by flame photometric detector (FPD). Under optimal conditions, TPhP-MIPs/GO-SPME-GC/FPD method was developed by yielding satisfactory ultralow limit of quantification (0.4 ng L−1); linearity (≥0.99), good intra- and inter-day precision for a single fiber and fiber-to-fiber reproducibility. The method was applied for the determination of TPhP in environmental water and the relative recoveries were found to be in the range from 70 to 110%. TPhP was detected in three out of four environmental water samples at concentration levels from 0.04 to 0.12 ng mL−1, illustrating light pollution of TPhP in most environmental water.

3062 – ASSESSING COMPATIBILITY OF ANTIMICROBIAL VIOLET-BLUE LIGHT FOR PATHOGEN REDUCTION OF RED BLOOD CELL CONCENTRATES

Transfusion-related sepsis is the most frequent infectious complication of blood transfusion. With millions of units transfused per year, product safety is key to public health but currently relies upon donor deferral and product testing. Pathogen reduction technologies can also be used, with several systems CE marked or FDA approved for platelet and plasma use, but only one CE marked for whole blood. 405 nm violet-blue light has recently demonstrated potential for in situ bacterial reduction of ex vivo stored plasma and platelet products, along with preliminary antiviral potential in plasma. This study assesses the potential compatibility of 405 nm antimicrobial light with red blood cell (RBC) components. Sheep RBC were analysed, showing light transmissibility and absorption characteristics over wavelengths of 220-1100 nm using neat–1000X dilutions. Irradiances of 10-100 mW/cm² 405 nm light were then applied to red cell samples with ∼1.3 & 7.8 mm depths over 10-60 minutes, giving doses of 9-360 J/cm². Treatment effects on cell integrity were demonstrated by microscopy and photometric detection of leaked haemoglobin using the Harboe method. RBC transmission analysis highlighted the high opacity of RBC suspension at 18% haematocrit with 1 cm depths, with peak absorption found to be at 417 nm. Results suggested the requirement of sample depths <1 cm to provide potential for penetration. Photometric analysis demonstrated RBC damage was influenced by the irradiance levels and exposure times used. Haemolysis increased by 0.37 & 1.26% over 15-60 minutes with 20 & 50 mW/cm² irradiances respectively. A greater increase of 5.06% was observed by 100 mW/cm² exposures over 15-30 minutes. Haemolysis rose sharply during 100 mW/cm² exposures and was supported by a visual decrease in stained viable cells. Low treatment doses ≤90 J/cm² with irradiances ≤50 mW/cm², showed potential compatibility, producing haemolysis below the 0.8% European limit. Future work will build on these findings and investigate the potential for antimicrobial efficacy of a 405 nm light treatment system at levels compatible with RBC physiology.

Photometric detection of internal gravity waves in upper main-sequence stars

Context. Massive stars are predicted to excite internal gravity waves (IGWs) by turbulent core convection and from turbulent pressure fluctuations in their near-surface layers. These IGWs are extremely efficient at transporting angular momentum and chemical species within stellar interiors, but they remain largely unconstrained observationally. Aims. We aim to characterise the photometric detection of IGWs across a large number of O and early-B stars in the Hertzsprung–Russell diagram, and explain the ubiquitous detection of stochastic variability in the photospheres of massive stars. Methods. We combined high-precision time-series photometry from the NASA Transiting Exoplanet Survey Satellite with high-resolution ground-based spectroscopy of 70 stars with spectral types O and B to probe the relationship between the photometric signatures of IGWs and parameters such as spectroscopic mass, luminosity, and macroturbulence. Results. A relationship is found between the location of a star in the spectroscopic Hertzsprung–Russell diagram and the amplitudes and frequencies of stochastic photometric variability in the light curves of massive stars. Furthermore, the properties of the stochastic variability are statistically correlated with macroturbulent velocity broadening in the spectral lines of massive stars. Conclusions. The common ensemble morphology for the stochastic low-frequency variability detected in space photometry and its relationship to macroturbulence is strong evidence for IGWs in massive stars, since these types of waves are unique in providing the dominant tangential velocity field required to explain the observed spectroscopy.

Dataset of certified food dye levels in over the counter medicines and vitamins intended for consumption by children and pregnant women.

Food, Drug, & Cosmetic (FD&C) dyes can be found in various products outside of food that are consumed by children. The amount of FD&C dyes used in commercial products is proprietary. Determining the contribution of dye intake from commercial products requires direct assessment of FD&C dyes in the products. This dataset contains the raw data of HPLC peak areas, absolute values, averages, SDs and % RSD for FD&C dyes in children's gummy vitamins, children's tablet vitamins, prenatal vitamins, children's cough/cold/allergy tablets & syrups, and children's pain reliever tablets & syrups obtained using high performance liquid chromatography with a photometric diode array detector (HPLC-PDA). The data can be used for further interpretations of dye intake in children, based upon dose levels suggested for distinct age groups, to evaluate the consumption of the FD&C dyes and accepted daily intake (ADIs) suggested for each FD&C dye by the United States Food & Drug Administration (US FDA). The variability associated within each category is critical for understanding how products on the market can differ between lot especially with large gaps between expiration dates. The interpretation of the data is described in “Certified Food Dyes in Over the Counter Medicines and Supplements Marketed for Children and Pregnant Women” in the Journal of Food and Chemical Toxicology [1].