Glass Cartridges Research Articles

Comparison of rebubbling rate between preloaded endothelium-in and preloaded no-touch endothelium-out Descemet membrane endothelial keratoplasty transplantation

BackgroundTo compare the difference in rebubbling rates between patients undergoing Descemet membrane endothelial keratoplasty (DMEK) with endothelium-in using a standard IOL cartridge and those with endothelium-out DMEK utilizing a no-touch technique with borosilicate glass cartridge transplantation.MethodsThis retrospective study included all eyes that underwent preloaded endothelium-in or endothelium-out DMEK transplantation from June 2019 to December 2023 at the Hanusch Hospital, Vienna, Austria. All DMEKs were harvested, prepared and preloaded at the European Eye Bank of Venice, Italy. DMEK surgeries were done by one experienced surgeon and the procedure was completed by air tamponade of the anterior chamber.ResultsOverall, 32 eyes each of 31 endothelium-out patients and of 29 endothelium-in patients were included. 32 preloaded endothelium-in procedures were followed by 32 preloaded endothelium-out procedures. Rebubbling rate for endothelium-in was 15/32 (47%) and for endothelium-out was 7/25 (28%) (p = 0.035, Pearson’s chi-squared test). Donor age was the most important variable for rebubbling in a random forest algorithm model (ROC: 0.69).ConclusionsRebubbling rate in endothelium-out DMEK was less than two-thirds compared to endothelium-in DMEK favoring no-touch endothelium-out DMEK as the preferred technique of DMEK transplantation.

Perfluorodecalin allows resuspension and prevents sediment solidification of extended-release drug formulations in primary packaging.

In this technical note we show with two simple experiments how Perfluorodecalin (PFD), an injectable perfluorocarbon, can be used as an agent for resuspending microparticulate suspensions in primary packaging containers for injection. Furthermore, we explain how this can be a substantial improvement regarding patient compliance in comparison to the commonly used gas headspace for resuspension. Our experiments are conducted with poly(lactic-co-glycolic acid) particles (often used in extended-release pharmaceutical formulations for injection) and in primary packaging that is commonly used in injection devices (glass cartridges). The results show that our method is feasible for resuspension and moreover even sediment solidification/caking is reduced. The differences between the two datasets collected are statistically significant with p < 0.01 in both cases.

Needle extraction device for rapid and quantitative gas chromatographic determination of volatile chlorinated hydrocarbons and benzene in soil

A rapid and quantitative analytical method for volatile chlorinated hydrocarbons and benzene, such as chloroethylene, dichloromethane, and carbon tetrachloride, in soil samples was developed using a needle-type extraction device packed with activated carbon-based adsorbents. The soil sample of 10 g was placed in a glass cartridge and fixed with quartz wool to make sure not to move during the extraction process. After the internal standard solution was spiked into the soil sample, the cartridge was sealed with a polytetrafluoroethylene adapter, and the needle extraction device was used to collect the headspace gas. Analytes were purged from the soil sample and collected on the adsorbent, while pure nitrogen gas was introduced to the soil sample during the sample collection. The sampling time was approximately 10 min for 100 mL of gas sampling. After the sampling process, the extraction needle was directly inserted into a heated injection port of gas chromatography equipped with flame ionization detector (GC-FID) or that hyphenated to mass spectrometry (GC–MS). The extracted VOCs were thermally desorbed and simultaneously introduced to a GC capillary column for subsequent separation and determination. The limit of detection and limit of quantification of all the examined analytes was less than 20 and 60 ng/10 g soil in GC-FID and less than 2.5 and 7.5 ng/10 g soil in the case of GC–MS. Linear calibration curves were obtained up to 10 μg/10 g soil for all the analytes. The relative standard deviations of the ratio of analyte peak area and internal standard peak area were less than 10%. The recovery and sensitivity of analytes confirmed in the proposed method were compared with that obtained with a standard method conventionally employed.

Safety evaluation of antibacterial and analgesic autoinjector devices for rapid administration during emergency situations: a crossover study in rabbits.

Objective:The objective of the present study was to evaluate the safety and tolerability of autoinjector devices (AIDs) in rabbits by intramuscular (i.m.) administration, using haematological and biochemical markers.Introduction:Emergency and mass casualty situations require immediate drug delivery for which AIDs are preferred. The tolerability of amikacin as antibacterial and buprenorphine as analgesic AID has been studied in rats by intraperitoneal administration. In the present study, it was evaluated in rabbits by i.m. administration.Methods:Water-filled glass cartridges (2.3–2.4 mL) were converted to amikacin (106 mg/mL) and buprenorphine (0.128 mg/mL) cartridges. Dual dose AID was used for i.m. administration (1.2 mL). The study was done as a crossover design on 12 rabbits. Initially, three rabbits each were given manually or AID, 57 mg/kg amikacin, and three rabbits each by manual or by AID, 0.07 mg/kg buprenorphine for 7 days. After 1 month, the injections were changed in the rabbits. In the place of manual injection, AID and in the place of amikacin, buprenorphine injection was given. This ensured that all rabbits received 14 injections, 7 manual and 7 AID consisting of 7 amikacin and 7 buprenorphine. 24 h before and 24 h after last drug administrations, blood was withdrawn from ear vein for haematological and biochemical estimations.Results:The rabbits were healthy, active and no sign of any injection-related changes were observed after administration of amikacin and buprenorphine by manually or by AID. The haematological and biochemical parameters showed similar changes in manual and AID administration of amikacin and buprenorphine.Conclusion:The present study of amikacin and buprenorphine by AID shows the safety of the device and is recommended for further experimentation. These AIDs are intended for self-administration during emergency and mass causality situation and are suitable for adults and children, as well as farm and pet animals.

An integrated DEM\u2013FEM approach to study breakage in packing of glass cartridges on a conveyor belt

The use of glass for pharmaceutical new applications such as high-technology drugs, requires the strictest container inertness. A common theme of paramount importance in glass container integrity preservation is the detailed mechanism driving the sudden failure due the crack propagation. Using a combination of discrete element method (DEM) and finite element method (FEM), a stress map for glass cartridges packed into an accumulation table and transported by a conveyor belt at a fixed velocity is obtained under realistic conditions. The DEM calculation provides a full description of the dynamics of the cartridges, as approximated by an equivalent sphere, as well as the statistics of the multiple collisions. The FEM calculation exploits this input to provide the maximum principal stress of different pairs as a function of time. Our analysis shows that, during their transportation on the conveyor belt, the cartridges are subject to several shocks of varying intensities. Under these conditions, a crack may originate inside the cartridge in the area of maximal tensile stress, and propagate outward. Estimated stresses are found in good agreement with real systems.Graphic abstract

Determination of low-molecule-weight aldehydes in packed drinking water by high performance liquid chromatography

A high performance liquid chromatographic (HPLC) method for the determination of formaldehyde, acetaldehyde and propionaldehyde in packed drinking water was developed. Aldehydes were derivatized with 0.5 mL DNPH (2,4-dinitrophenylhydrazine) reagent and 0.1 mL 2 M perchloride at 55°C in 60 minutes, then adsorbed in C18 glass cartridge (was performed), eluted with 5 mL acetonitrile and finally determined by HPLC. Formaldehyde, acetaldehyde and propionaldehyde-DNPH-derivatives were seperated on a Cosmosil 5C18-MS column by using acetonitrile/D.I. water (55/45, v/v) as a mobile phase, and detected with UV 360 nm. Recovery studies were performed by fortifying D.I. water with formaldehyde, acetaldehyde and propionaldehyde at various concentrations from 2 to 200 ppb. Recovery rates were in the range of 84.4 - 103.2%, 90.2 - 122.1 % and 60.8 - 100.4%. The detection limits for all three aldehydes were 1 ppb. Sixty-three packed drinking water samples collected from various markets were analyzed. These results were well below the guideline for drinking water quality by WHO (900 μg/L).

Descemet membrane endothelial keratoplastyDMEK -Donor and recipient step by step

In 2020 Descemet membrane endothelial keratoplasty (DMEK) has become the gold standard in Germany for the treatment of corneal endothelial diseases; however, the widespread use of DMEK was initially limited due to problems with donor preparation and the difficulty of correctly and gently unfolding the endothelial Descemet membrane (EDM) in the anterior chamber. Following the situational donor selection, the safe single-handed donor preparation of the cornea without tearing or even rupturing the EDM, including the indispensable peripheral semicircular orientation marking. Also presented is a step by step atraumatic loading of the glass cartridge, the introduction of the EDM roll into the anterior chamber, and its safe step by step unfolding based on (1)the sequential use of jets of fluid, (2)repeated tapping on the peripheral/central cornea, (3)controlled flattening of the anterior chamber, (4)use of air bubbles of defined size and finally, the fixation of the EDM in correct orientation to the back of the host cornea with agas bubble. Since every wrong step with DMEK can have far-reaching consequences for patient and surgeon, this step by step pragmatic approach should minimize the incidence of donor tissue damage and failure in patient maneuvers.

Techniques for graft preparation in DMEK

AbstractDMEK is a surgical technique that is now known by many surgeons and is gradually replacing other surgical techniques in the management of corneal endothelial pathologies. There are currently several different preparation techniques, the most famous and most widely used being the initial technique described by Guerrit Melles. During this procedure, the Descemet membrane is detached using one or two forceps from the periphery. The isolated graft rolls spontaneously with the endothelium outside. It is then aspirated into a glass cartridge before being injected into the anterior chamber. Another preparation technique we have described is to detach the Descemet membrane by hydrodissection after inverting the corneal curvature. It is then possible to roll the graft with the endothelium inside, and mark it easily before inserting it into an injection cartridge. The main advantages are the easier unfolding of the graft and the assurance of positioning it in the right position. A third technique consists in detaching the Descemet membrane by performing a Big Bubble technique but it is not always possible to isolate a graft larger than 7 mm. Whatever the technique, the most important thing for each surgeon is to train regularly in order to choose the procedure that best suits him. There does not seem to be any difference in terms of endothelial cell loss depending on each technique. It should also be kept in mind that the performance of a DMEK is accompanied by a greater number of post‐operative graft detachment and that other endothelial graft techniques should be proposed in case of specific surgical conditions. In addition, the precut techniques proposed by corneal banks are now making the surgical procedure even easier and faster.

Safety analysis and results of a borosilicate glass cartridge for no-touch graft loading and injection in Descemet membrane endothelial keratoplasty.

The aim of this study was to investigate the clinical outcome after standardized DMEK using a glass injector. A total of 254 patients undergoing DMEK surgery using a disposable DMEK borosilicate glass cartridge system were included in this retrospective study. The mean follow-up time was 13.2months (SD ± 8.1, range 6-36months). The used glass cartridge system has an aperture diameter of 1.6mm and a posterior loading orifice of 4.29mm. Scanning electron microscopy (SEM) was used for estimation of the surface relief of the glass cartridge and comparison with a standard plastic injector cartridge. Mean endothelial cell count of donor grafts was 2465 cells/mm2 (SD ± 199). After 6weeks of DMEK endothelial cell count decreased by - 28.6% to 1759 cells/mm2 (SD ± 435) (Wilcoxon p = 0.001) and remained stable at the final follow-up at 1735 cells/mm2 (SD ± 442) (Wilcoxon p = 0.89). SEM showed smoother surface of the glass cartridge in comparison with a plastic cartridge. This study showed that this simple and effective DMEK cartridge seems to be a safe and viable device for minimized graft manipulation during DMEK surgery.

Effect of Headspace and Trapped Volatile Organic Compounds (VOCs) of the Chinese Caterpillar Mushroom, Ophiocordyceps sinensis (Ascomycetes), against Soil-Borne Plant Pathogens.

Headspace volatile metabolites produced by Ophiocordyceps sinensis were tested against soil-borne plant pathogens (namely, Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. cubense, Thanatephorus cucumeris, Athelia rolfsii, and Macrophomina phaseolina). Diffusible volatile metabolites produced by O. sinensis inhibited 52% and 48% of the mycelial growth of F. oxysporum f. sp. lycopersici and F. oxysporum f. sp. cubense, respectively. In addition to inhibiting mycelial growth, the headspace volatile metabolites also induced several morphological changes in the culture characteristics and mycelia of the tested fungi. Stunted and depressed colony growth was observed for F. oxysporum f. sp. cubense and F. oxysporum f. sp. lycopersici. The headspace volatile compounds produced by O. sinensis were trapped in a glass cartridge (Porapak Q). The trapped compounds were eluted from the column by using hexane and then, by using gas chromatography-mass spectrometry, were identified as tetratetracontane, 1(2H)-naphthalenone, 3, 4-dihydro-3-methyl, 3-hexenoic acid, 1-methyl-3-ethyladamantane, and phenol, 3-ethyl.

Occurrence of phthalate acid esters (PAEs) in the northwestern Mediterranean Sea and the Rhone River

Phthalate acid esters (PAEs) which are mainly anthropogenic molecules with endocrine disrupting effects in animals and humans, have been detected in terrestrial and aquatic environments. However, little is known about their distribution in the Mediterranean Sea, mainly because of analytical difficulties and the high possibility of ambient sample contamination. Here, we report the optimization of an existing protocol for the determination of PAEs in seawater and freshwater samples, as well as the first estimation of the source and distribution of phthalates acid esters (PAEs) in coastal waters from the NW Mediterranean Sea. By passing 1L of sample through glass cartridges packed with 200mg of Oasis HLB and eluted with 6mL of ethyl acetate followed by gas chromatography and mass spectrometry (GC/MS) analyses, the recoveries for DMP, DEP, DPP, DiBP, DnBP, BzBP, DEHP and DnOP were 101, 98, 115, 110, 99, 98, 103 and 95%, respectively, with acceptable blank values (below 0.4–4.0% of the masses measured in different seawater samples). By using this method, we detected PAEs in the Marseilles coastal area, offshore (2000m depth) and in the Rhone River with total concentrations ranging from 75.3ng/L offshore in surface water to 1207.1ng/L a few meters above the bottom of the Marseilles Bay. High concentrations were also observed in deep waters offshore (310.2ng/L) as well as in the Rhone River (615.1ng/L). These results suggest that Marseilles urban area, Rhone River and sediment are potential sources of PAEs in the areas studied.In the Rhone River, DEHP was the most abundant PAE (66.1%) followed by DiBP (20.5%) and DnBP (6.6%), whereas a gradual change was observed in the plume of the river with increasing salinity. In the Marseilles Bay, DiBP was the most abundant PAE at the surface (47.3% of total PAEs) followed by DEHP (22.7%) and DnBP (19.1%), whereas DnBP was predominant (38.6%) a few meters above the bottom. By contrast, DEHP was the dominant species in the first 50m (66.9–76.7%) offshore followed by DnBP (10.9–15.2%), whereas DnBP was the most abundant (57.0–72.6%) followed by DEHP (20.1–33.1%) in the deepest waters. This study suggests that in addition to direct PAEs injection in marine waters, different processes regulate PAE distribution in Mediterranean Sea including photochemical oxidation reactions, bacterial degradation and possible diffusion following release from marine litter near the bottom.

Polydimethylsiloxane-coated partitioning sample collection device for the precise quantification of polycyclic aromatic hydrocarbons in air.

A novel partitioning collection device comprising a glass cartridge packed with poly(dimethylsiloxane)-coated macroporous silica particles was developed for the precise quantification of polycyclic aromatic hydrocarbons in air. The analyte collection and elution performances achieved using different amounts of poly(dimethylsiloxane) coating were quantitatively evaluated. The sample retention power increased with increasing the coating, and more than 250 L of air could be collected without analyte breakthrough at a sampling temperature of 35°C. During the air collection, the moisture in the air was not retained on the particles due to the hydrophobic surface of the sorbent. A complete and rapid elution of the collected analytes from the device was accomplished by the passage of only 10 mL of acetone with ultrasonication for 1 min. The proposed method was successfully applied for the determination of airborne polycyclic aromatic hydrocarbons in tunnel air.

Silver ion solid‐phase extraction cartridges employing glass housings overcome the limitations observed in the GC analysis of animal lipids with low trans fatty acid content

Custom made silver ion solid‐phase extraction (Ag+‐SPE) cartridges with glass housing were evaluated to see whether they could be used to analyze the trans fatty acids (TFA) in animal products when present at low concentration. Previous attempts were not successful to identify and characterize the TFA using commercial Ag+‐SPE cartridges, because of the coelution of artifacts from these cartridges. The glass cartridges proved successful to identify the low levels of TFA present in horse and wild boar meat. It is recommended that the supplier make available Ag+‐SPE cartridges in glass housing to avoid the problem of interferences.Practical applications: It was previously shown that commercially available silver ion solid‐phase extraction (Ag+‐SPE) cartridges could not be used to analyze biological samples with low levels of TFAs, because of interfering contaminants that eluted from the polypropylene housing. Custom made glass cartridges were generously provided by the supplier, and they proved successful to fractionate the geometric isomers of horse and wild boar lipids both of which are known to contain low levels of TFAs. Subsequent gas chromatographic analysis made it possible to identify the trans and cis isomers without interference of contaminants. The unsaturated fatty acid fractions from these glass cartridges were also free of contaminants.Ag+‐SPE cartridges in glass housing are recommended to resolve and identify the trans isomers when present at low concentrations in biological samples.

Quantifying bisphenol A in maternal and cord whole blood using isotope dilution liquid chromatography/tandem mass spectrometry and maternal characteristics associated with bisphenol A

Bisphenol A (BPA) is endocrine disrupting chemical that have been detected among general population. Exposure levels among pregnant women and their fetus are yet largely unknown among Japanese. We have developed a new method of measuring total BPA in whole blood samples by using isotopic dilution liquid chromatography-tandem mass spectrometry (ID-LC/MS/MS). For eliminating possible contaminations, we have used glass cartridge instead of polypropylene cartridge and successfully reduced background levels. Additionally gap retention technique was applied to improve sensitivity. We also confirmed no external contamination by measuring free BPA in the samples. The limit of quantification (LOQ) was 0.040 ng/ml. With this developed method, we determined total BPA concentrations of 59 maternal blood at delivery and 285 cord blood samples in prospective birth cohort study and investigated factors possibly related to total BPA levels. Total BPA levels ranged from below LOQ to 0.419 ng/ml and for maternal blood and from below LOQ to 0.217 ng/ml for cord blood, respectively. The geometric mean was 0.051 ng/ml for maternal blood and 0.046 ng/ml for cord blood, respectively. Although no correlation was observed between maternal and fetal blood levels of total BPA, our result suggested fetal exposure to BPA. We have found that younger mothers, frequent beef and pork consumption during pregnancy were positively associated with maternal total BPA levels. We confirmed in utero exposure to BPA, which highlights the importance of further studies of investing the effects of fetus BPA exposure on health outcomes.

Formic and Acetic Acids in Degradation Products of Plant Volatiles Elicit Olfactory and Behavioral Responses from an Insect Vector.

Volatile phytochemicals play a role in orientation by phytophagous insects. We studied antennal and behavioral responses of the Asian citrus psyllid, Diaphorina citri, vector of the citrus greening disease pathogen. Little or no response to citrus leaf volatiles was detected by electroantennography. Glass cartridges prepared with β-ocimene or citral produced no response initially but became stimulatory after several days. Both compounds degraded completely in air to a number of smaller molecules. Two peaks elicited large antennal responses and were identified as acetic and formic acids. Probing by D. citri of a wax substrate containing odorants was significantly increased by a blend of formic and acetic acids compared with either compound separately or blends containing β-ocimene and/or citral. Response surface modeling based on a 4-component mixture design and a 2-component mixture-amount design predicted an optimal probing response on wax substrate containing a blend of formic and acetic acids. Our study suggests that formic and acetic acids play a role in host selection by D. citri and perhaps by phytophagous insects in general even when parent compounds from which they are derived are not active. These results have implications for the investigation of arthropod olfaction and may lead to elaboration of attract-and-kill formulations to reduce nontarget effects of chemical control in agriculture.

Consolidated Vacuum Sublimation Module: a Purification Apparatus and Process for Solid-Phase Materials

A consolidated Vacuum Sublimation Module [cVSM] provides engineering improvements over conventional sublimation apparatus. As implied, the cVSM is structurally modular and it comprises: valve stem unit, valve/Collector/jacket unit, lower glass body, FKM seals, threaded PTFE bushing, and an internal glass cartridge [see US patent 7794694]. In association with the cVSM, a batch sublimation process was developed to purify solid-phase materials such as ferrocene, perylene, oxalic acid, and pentachlorobenzene.To effect sublimation, the lower glass body is controllably heated to establish a vertical temperature gradient. The temperature gradient along the [evacuated] lower body surface was measured versus input electric power. At steady state, an input of ~37 watts generated +530K at z=0 and +314K near z=95 mm. When operated with natural cooling, the starting material recovery was typically ≥95 mass%. Design features of said Module include: concentric multi-tubular geometry, elongated tapered Collector, positively compressed seals, natural Collector cooling, minimal power consumption, transparency, and glovebox compatibility. The [static vacuum] leakage of an empty cVSM measured <20 ppmv of air per hour. Lastly, the prototype Module has been moderately scaled-up and demonstrated.

Health risk assessment for inhalation exposure to particle-bound polycyclic aromatic hydrocarbons from household cooking in northern Taiwan

Background: Food cooking generates lots of harmful fine and ultrafine particles.Many occupational studies have shown that the incremental lifetime cancer risk (ILCR) caused by exposure to polycyclic aromatic hydrocarbons (PAHs) in cooking fume was much higher than the suggested acceptable limit of 10-6. However, the higher exposure level of occupational studies cannot represent the exposure of the general population. Aim: To assess the health risk for the exposure to cooking fume of daily household cooking, since these data may be more representative and is currently limited in Taiwan Method: We took particle and gaseous PAHs samples using a Micro-Orifice Uniform-Deposit Impactors and glass cartridge packed with Amberlite XAD-16 polymeric adsorbent, respectively, during cooking periods from five families without smoker in northern Taiwan. These samples were extracted and then analyzed by theGC/MS. The ILCR caused by exposure tocooking fumewas evaluated based on PAHs analysis result.We also monitored the 24-hour particle concentrations profile by using a Scanning Mobility Particle Sizer and a 6-channel optical particle counter. Result: Although gaseous PAHs contributed more than 85% of the total PAHs, particulate PAHs percentage increased with ring number of PAHs and contributed the most of banzo[a]pyrene equivalent concentration (B[a]Peq). The B[a]Peq is significantly positive correlated with the mass of larger particles (&gt;3.2 ?m) but negative correlated with that of particles smaller than 0.056?m, indicating that most toxic PAHs deposited on larger particles. The ILCR caused by household cooking fume is lower than those reported in occupational studies. However, the ILCR is higher than10-5, implying that even the exposure to PAHs from daily household cooking could result in a significant cancer risk. Conclusion: Most toxic PAHs of household cooking fume deposited on large particles and caused a considerable cancer risk in northern Taiwan.

Pressure drop of structured cartridges with fiber–glass catalysts

The pressure drop in the structured cartridges with fiber–glass catalysts, providing the gliding flow of the reaction mixture along the catalyst fabric layers was studied. It was found that unit hydraulic resistance of such cartridges significantly depends upon the size of the flow passages and the geometry of the structuring gauzes, at the same, practically not depending upon the structure of the fabric and upon the external shape of the cartridge. The dependence of the pressure drop ΔP upon flow velocity v in all cases is close to the second order: ΔP=ζρv2L, while pressure drop coefficient in the cartridges with corrugated gauze practically does not depend upon flow velocity and may be described by empiric equation ζ av=1744∗d−1.58 (m−1) where d – equivalent flow passage size (m). The structured fiber–glass cartridges with structuring gauzes were found to be partially anisotropic, with commensurable pressure drops in case of flow moving along the passages and across passages, but along the catalyst fabric planes, while the pressure drop for the flow perpendicular to the catalyst fabric planes is much higher.

Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS)

Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology.

Evaluation of Molecularly Imprinted Polymers for the Simultaneous SPE of Six Corticosteroids in Milk

A molecularly imprinted solid-phase extraction procedure was optimized for the simultaneous extraction of six corticosteroids commonly employed in animal husbandry. Two different molecularly imprinted polymers (MIPs) were synthetized by precipitation polymerization, using dexamethasone (DM) and flumethasone (FLU) as template molecules. Methacrylic acid was used as functional monomer and divinylbenzene as cross-linker, and the selected porogen was a solution of acetonitrile and toluene (3:1). After removal of the template, both molecularly imprinted and non-imprinted polymers were placed into glass cartridges to perform solid-phase extraction experiments. Loading, washing and elution steps were optimized for each MIP in order to test the suitability of the selected template molecules DM and FLU to provide selective polymeric sites for corticosteroids. Recovery measurements were performed by HPLC–MS/MS. The maximum recovery for all corticosteroids was achieved with DM-based MIP when loading with toluene and washing with 5% acetonitrile in toluene, and eluting with 1% acetic acid in methanol. When cleaning-up milk samples spiked with corticosteroids, the recovery of DM-based polymer decreased. However, the efficiency of FLU-based polymer clearly improved even when a strong matrix effect was observed. Additionally, two frequently used commercial solid-phase extraction (SPE) cartridges were compared with imprinted polymers. The commercial SPE cartridges gave good recoveries only for specific analytes while MIPs provided good recoveries for all analyzed corticosteroids.