Sample Vial Research Articles

Optical Imaging and Molecular Sequencing of a Preserved Collection of Bivalve Larvae

From the 1980s through 1995, scientists at numerous marine, coastal, estuarine, and freshwater laboratories spawned bivalves to provide larvae for use in identifying species based on larval hinge structures and gross shell morphometry. These larvae were preserved in 95% ethanol and stored in sample vials, many of which dried out over the years. Advantage was taken of 50 of 56 species from this collection (and two additional species that were not in the collection for a total of 52 species) to explore the use of optical techniques (polarized light and a full-wave compensation plate) to highlight birefringence patterns of larval shells to discriminate individual species. Representative images of various developmental stages of 77% (40/52) of the larval bivalve species in the collection were successfully imaged. Similarities across birefringence patterns were observed at the taxonomic ordinal and familial level. Molecular polymerase chain reaction techniques were used in an effort to sequence many of the dried-out specimens and they successfully identified 19% (10/52) of the larval bivalve species with matches in GenBank. Here it has been demonstrated that optical techniques are efficient for imaging dried-out larval bivalve shells for classification purposes and we present successful sequences of 10 species of bivalve larvae from the preserved collection.

Quantifying the mechanical and histological properties of thrombus analog made from human blood for the creation of synthetic thrombus for thrombectomy device testing

BackgroundUntreated ischemic stroke can lead to severe morbidity and death, and as such, there are numerous endovascular blood-clot removal (thrombectomy) devices approved for human use. Human thrombi types are highly...

Determination of Aromatic Arsines in Environmental Solids by Direct Thermal Desorption Gas Chromatography

ABSTRACTTo quantify aromatic arsines in the environment, such as World War I era chemical warfare agents and degradation products of arsenicals used in agriculture, a sensitive, selective, and direct method is needed. We describe the development and optimization of a method for the measurement of trace levels of triphenylarsine used as a model aromatic arsenic compound. Triphenylarsine was determined at low µg/g levels in sand, soil, and lake sediment by thermal desorption before gas–liquid chromatography (GC) with mass spectrometric and pulsed flame photometric detection. The dithiol derivative of phenylarsonic acid was used as an internal standard, thereby significantly improving the precision of the method. The desorption conditions were studied and found to be optimal at 350°C for 15 min. Significant improvement in precision was realized by preparing the solid samples as slurries in acetone and by inserting a small (∼100 mg) quartz wool plug into the sample vial. The method was applied to determine triphenylarsine in authentic soil and sediment samples that had been fortified with triphenylarsine and aged for at least 15 days. Recoveries for soil samples ranged from 84.3 ± 2.3 to 87.7 ± 1.3%, while lower recoveries were obtained for sediment samples (75.1 ± 3.0%). The detection limit for triphenylarsine in soil was 3.14 ng with a precision of 7.10% (n = 4). Using these optimized conditions, the performance of the direct thermal desorption GC method for sample introduction was greatly improved compared to methods that have been reported in the literature.

Determining Biodegradation Kinetics of Hydrocarbons at Low Concentrations: Covering 5 and 9 Orders of Magnitude of Kow and Kaw.

A partitioning-based experimental platform was developed and applied to determine primary biodegradation kinetics of 53 hydrocarbons at ng/L to μg/L concentrations covering C8-C20, 11 structural classes, and several orders of magnitude in hydrophobicity and volatility: (1) Passive dosing from a loaded silicone donor was used to set the concentration of each hydrocarbon in mixture stock solutions; (2) these solutions were combined with environmental water samples in gastight auto sampler vials for 1-100 days incubation, and (3) automated solid phase microextraction (SPME) coupled to GC-MS was applied directly on these test systems for measuring primary biodegradation relative to abiotic controls. First order biodegradation kinetics were obtained for 40 hydrocarbons in activated sludge filtrate, 18 in seawater, and 21 in lake water. Water phase half-lives in seawater and lake water were poorly related to hydrophobicity and volatility but were, with a few exceptions, within a factor of 10 or shorter than BioHCwin predictions. The most persistent hydrocarbons, 1,1,4,4,6-pentamethyldecalin, perhydropyrene, 1,2,3,6,7,8-hexahydropyrene, and 2,2,4,4,6,8,8-heptamethylnonane, showed limited or inconsistent degradation in all three environmental media. This biodegradation approach can cover a large chemical space at low substrate concentrations, which makes it highly suited for optimizing predictive models for environmental biodegradation.

Determination of 3-chloro-1,2-propanediol in polyamideamine epichlorohydrin resin solution by reaction-based headspace gas chromatography.

We report on a headspace gas chromatographic method for determining the content of 3-chloro-1,2-propanediol in polyamideamine epichlorohydrin resin solution. It was based on quantitatively converting 3-chloro-1,2-propanediol to formaldehyde by periodate oxidation in a closed headspace sample vial at a room temperature for 10min, and then to methanol by borohydride reduction at 90°C for 40min followed by the headspace gas chromatographic measurement. The results showed that the present method has an excellent measurement precision (relative standard deviation <2.60%) and accuracy (recoveries from 96.4-102%) in 3-chloro-1,2-propanediol analysis. The limit of quantitation was 0.031mg/mL. It is simple and suitable for determining the 3-chloro-1,2-propanediol content in polyamideamine epichlorohydrin resin solution.

A fully automated analytical platform integrating water sampling-miniscale-liquid-liquid extraction-full evaporation dynamic headspace concentration-gas chromatography-mass spectrometry for the analysis of ultraviolet filters

A fully automated analytical platform that seamlessly integrates online water sampling-sample preparation-gas chromatography-mass spectrometry (GC-MS) was developed for ultraviolet (UV) filters in this work. The online water sampling system consisted of a conventional sample vial (slightly modified to have both inlet and outlet ports), two tubings and a peristaltic pump, which controlled the water flow into and out of the vial. The sample preparation segment consists of miniscale liquid-liquid extraction (msLLE), coupled to full evaporation dynamic headspace concentration (FEDHS) on a commercial dual-arm autosampler. The extract from the msLLE step was subjected to a derivatization step, before being passed through a Tenax TA sorbent tube at the FEDHS stage. UV filters were used as model compounds in this work due to their potential endocrine and developmental toxicities, including benzhydrol, 2-ethylhexyl salicylate, homosalate, 2-hydroxy-4-methoxybenzophenone, 3-(4′-methylbenzylidene) camphor and benzophenone. The analytes (of which the first four underwent derivatization, by virtue of them possessing hydroxyl groups, but not the last two) were concentrated on the sorbent, and were thermally desorbed before being introduced to the GC-MS system for analysis. An orthogonal array design (OAD) strategy was employed to facilitate the optimization of the msLLE and derivatization factors while univariate optimization was performed for FEDHS. The optimized settings achieved low limits of detection (0.6–9.7 ng L−1) with good linearity (r2 ≥ 0.9926), and satisfactory absolute extraction recoveries (62.0%–80.7%) were obtained. The fully automated online water sampling-extraction/concentration-detection approach was demonstrated by applying it to the analysis of swimming pool water. Relative recoveries of the analytes in the pool water ranged from 85.4% to 118.2%. The described procedure has the potential to be a fully automated online water sampling-msLLE-FEDHS-GC-MS platform for the purpose of conducting routine onsite water analysis.

Dacroscintigraphy by Pediatric Dropper Technique: A User-friendly Instillation Procedure of Radiotracer.

Context:Instillation or application of the radiotracer over the tear film is one of the important parts of dacroscintigraphy. Our study explains the value of an improvised dropper technique so that desired amount of radioactivity in desired volume can be instilled over the tear film.Aim:The aim of the study is to introduce a simple and convenient instillation method based on dropper technique for performing dacroscintigraphy. This improvised dropper technique can be used so that desired amount of radioactivity in desired volume can be instilled over the tear film. The objectives of this experiment are to measure the volume and activity of each drop from the dropper.Settings and Design:Experiment of volume and activity measurement standardization was carried out in two parts. In the first part, we calculated the volume of each drop indirectly to standardize the volume of drop. In the second part, we standardized the activity in each drop by measuring it in a dose calibrator.Subjects and Methods:In this study, we used a common pediatric dropper of approximately 1 ml capacity, radioactivity (99mTcO4 pertechnetate), sample vial (container), vial holder, a pair of nonsterile gloves, dose calibrator, etc., Experiments of volume and radioactivity standardization were carried out in two parts. The first part of experiment calculated volume of each drop indirectly, and in the second, we standardized the activity in each drop by measuring it in dose calibrator. Statistical analysis used: Analysis of variance test was used to calculate the correlation of readings by same individual as well as among the three individualsResults:After analysis of result obtained, it was understood that there was no significant difference found in volume and activity of each drop in the readings recorded by same individual as well as among the three individuals. The calculated activity and observed activity were 86.64 and 79.16 μCi, respectively. The difference was only 8.63% lying within acceptable limits.

Portable Cyanobacteria Detection Fluorometer with Current-conveyor Transimpedance Amplifiers

A portable fluorometer has been developed for cyanobacteria detection by exploiting commercially available low-cost photodiodes. Particularly, the front-end detection circuit was integrated on-chip by using a 0.11-μm CMOS process to realize the high transimpedance gain of 99.7 dBΩ with low current consumption of 1.4 mA from a single 1.5-V supply, hence providing a low-power solution with small form-factor in the applications of portable cyanobacteria detection. For measuring fluorescence intensity of cyanobacteria, two quantum dots of QDSUB565/SUB and QDSUB655/SUB were employed into a NanoGene assay for mcyD gene(synthetase of toxic microcystin) detection of Microcystis aeruginosa, resulting in two different readout voltages. Various operational parameters (e.g. distance, angle between laser emission and vial sample, etc) were investigated for the proposed fluorometer. Measurements demonstrated that the mcyD gene hybridized with QDSUB565/SUB and QDSUB655/SUB was quantitatively detected, i.e. the normalized output voltage (QDSUB655/SUB/QDSUB565/SUB) was linearly proportional to the mcyD gene copy numbers (y = 0.25 log x – 0.25). Besides, the wireless transfer of the quantitative data was performed via Bluetooth.

A simple and efficient headspace gas chromatographic method for the determination of carboxyl groups in nanofibrillated cellulose

This paper reports on a headspace gas chromatography method (HS-GC) for efficient determination of carboxyl groups in nanofibrillated cellulose (NFC). By pretreating the NFC suspension with a strong acid cation exchange resin for 30 min, the carboxyl groups in NFC were converted to the carboxyl acids. The pretreated suspension was added into a closed headspace sample vial containing bicarbonate solution. By HS-GC measuring the CO2 produced from the reaction between carboxyl acids and bicarbonate (10 min at 60 °C), the content of carboxyl groups in NFC can be determined. The results showed that the relative standard deviation of the method in the repeatability testing was < 3.7% and the limit of quantitation was about 0.1 mmol/g. Relative differences between the HS-GC and the reference (a conductometric titration) method were within 15.0%. The present method is simple and efficient, and suitable to be used for determining the content of carboxyl groups in NFC in the related applications.

Fabrication of CaFe2O4/MoS2 hybrid and its application for adsorption of paclitaxel chemotherapy medication in injection vial and water samples

Non-modified molybdenum disulfide (MoS2) is known to adsorb various compounds. However, in case of very small particle sizes and high dispersibility, ordinary centrifugation and filtration fail to separate MoS2 from aqueous media limiting, its applicability to solid-phase extraction. To overcome this shortcoming, we have prepared a nanohybrid consisting of MoS2 and nanoparticles of CaFe2O4. Detailed characterizations through field emission scanning electron microscopy, vibrating sample magnetometer, X-ray diffraction and energy-dispersive X-ray techniques confirmed the formation of the hybrid. The adsorption behavior was systematically accessed through kinetic, equilibrium and thermodynamic experiments. The nanohybrid was applied to the adsorption of paclitaxel. The adsorption capacity was 68.96 mg g−1. Also, the method was successfully applied to the preconcentration of the analytes in (spiked) injection vial of paclitaxel and water samples.

Total Mercury Determination in Muscle and Liver Tissue Samples from Brazilian Amazon Fish Using Slurry Sampling.

This paper presents a slurry sampling method for total mercury determination by graphite furnace atomic absorption spectrometry (GFAAS) in tissue of fish from the Amazon. The tissue samples were lyophilized and macerated, and then the slurry samples were prepared by putting 20mg of tissue, added to a solution containing Triton X-100, Suprapur HNO3, and zirconium nitrate directly in sampling vials of a spectrometer. Mercury standard solutions were prepared under the same conditions as the slurry samples. The slurry samples and the mercury standard solutions were sonicated for 20s. Twenty microliters of slurry samples were injected into the graphite tube, which contained an internal wall lined with tungsten carbide. Under these conditions, it was possible to thermally stabilize the mercury up to an atomization temperature of 1700°C. The method was validated by mercury determination in reference materials DORM-4 and DOLT-4. The LOD and LOQ were 0.014 and 0.045mgkg-1, respectively, and recovery percentages in relation to the concentration values were certified in the order of 98%.

Determination of the content of alkyl ketene dimer in its latex by an ionic-liquid assisted headspace gas chromatography

This paper reports on an ionic-liquid assisted headspace gas chromatographic (HS-GC) for the determination of the content of alkyl ketene dimer (AKD) in its latex samples, in which the GC system was equipped with a thermal conductivity detector (TCD). The method was based on the AKD hydrolysis conducted in 1-butyl-3-methylimidazolium chloride (ionic-liquid) added medium at 100°C for 10min in a closed headspace sample vial, and the measured CO2 (the resulting product of the hydrolysis) by HS-GC. The results showed that the present method has a good measurement precision (RSD <2.3%) and accuracy (recoveries from 96 − 105%), and the limit of quantitation (LOQ) is 0.9%. The present method is very suitable to be used for the routine check of AKD content in its latex sample in mill applications. The study also showed that the content of AKD in the tested commercial latex samples were in the range of 3.5–12%.

Simple, Low-Cost and Reliable Device for Vacuum-Assisted Headspace Solid-Phase Microextraction of Volatile and Semivolatile Compounds from Complex Solid Samples

A new simple, low-cost, reliable vacuum-assisted headspace solid-phase microextraction (VA-HS-SPME) device was fabricated and evaluated considering the strengths and weaknesses of previously reported systems. The device can be applied for analysis of solid and liquid samples without sample loss or vacuum loss during the evacuation process, in contrast to similar setups. Additionally, it is simpler, lower cost, and more operator friendly for direct extraction of volatiles and semivolatiles from complicated solid matrices. It was coupled with gas chromatography-flame ionization detection (GC-FID) and applied for direct extraction and determination of polycyclic aromatic hydrocarbons (PAHs) in polluted soil samples, without any sample preparation steps. Parameters affecting the performance of the developed method, such as extraction temperature and time, vacuum level, volumes of vacuum chamber and sample vial, and desorption condition, were investigated and optimized. Under the optimal conditions, calibration curves were linear over the range of 0.01–2 μg g−1 (R 2 > 0.996). The limits of detection (LODs) were found to lie in the range of 0.3–0.8 ng g−1, while the relative standard deviations (RSDs) for six replicate analyses were 5.3–7.1%. The developed VA-HS-SPME/GC-FID procedure was used for ultrasensitive determination of PAHs in contaminated soil samples; the results were statistically in agreement with those obtained using a validated ultrasonic solvent extraction (USE) method.

Quality by design approach in the development of an ultra-high-performance liquid chromatography method for Bexsero meningococcal group B vaccine

Bexsero is the first approved vaccine for active immunization of individuals from 2 months of age and older to prevent invasive disease caused by Neisseria meningitidis serogroup B. The active components of the vaccine are Neisseria Heparin Binding Antigen, factor H binding protein, Neisseria adhesin A, produced in Escherichia coli cells by recombinant DNA technology, and Outer Membrane Vesicles (expressing Porin A and Porin B), produced by fermentation of Neisseria meningitidis strain NZ98/254. All the Bexsero active components are adsorbed on aluminum hydroxide and the unadsorbed antigens content is a product critical quality attribute. In this paper the development of a fast, selective and sensitive ultra-high-performance liquid chromatography (UHPLC) method for the determination of the Bexsero antigens in the vaccine supernatant is presented. For the first time in the literature, the Quality by Design (QbD) principles were applied to the development of an analytical method aimed to the quality control of a vaccine product. The UHPLC method was fully developed within the QbD framework, the new paradigm of quality outlined in International Conference on Harmonisation guidelines. Critical method attributes (CMAs) were identified with the capacity factor of Neisseria Heparin Binding Antigen, antigens resolution and peak areas. After a scouting phase, aimed at selecting a suitable and fast UHPLC operative mode for the vaccine antigens separation, risk assessment tools were employed to define the critical method parameters to be considered in the screening phase. Screening designs were applied for investigating at first the effects of vial type and sample concentration, and then the effects of injection volume, column type, organic phase starting concentration, ramp time and temperature. Response Surface Methodology pointed out the presence of several significant interaction effects, and with the support of Monte-Carlo simulations led to map out the design space, at a selected probability level, for the desired CMAs. The selected working conditions gave a complete separation of the antigens in about 5min. Robustness testing was carried out by a multivariate approach and a control strategy was implemented by defining system suitability tests. The method was qualified for the analysis of the Bexsero vaccine.

Optimization of total vaporization solid-phase microextraction (TV-SPME) for the determination of lipid profiles of Phormia regina, a forensically important blow fly species.

A new method has been developed for the determination of fatty acids, sterols, and other lipids which naturally occur within pupae of the blow fly Phormia regina. The method relies upon liquid extraction in non-polar solvent, followed by derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) w/ 1% trimethylchlorsilane (TMCS) carried out inside the sample vial. The analysis is facilitated by total vaporization solid-phase microextraction (TV-SPME), with gas chromatography-mass spectrometry (GC-MS) serving as the instrumentation for analysis. The TV-SPME delivery technique is approximately a factor of five more sensitive than traditional liquid injection, which may alleviate the need for rotary evaporation, reconstitution, collection of high performance liquid chromatography fractions, and many of the other pre-concentration steps that are commonplace in the current literature. Furthermore, the ability to derivatize the liquid extract in a single easy step while increasing sensitivity represents an improvement over current derivatization methods. The most common lipids identified in fly pupae were various saturated and unsaturated fatty acids ranging from lauric acid (12:0) to arachinoic acid (20:4), as well as cholesterol. The concentrations of myristic acid (14:0), palmitelaidic acid (16:2), and palmitoleic acid (16:1) were the most reliable indicators of the age of the pupae. Graphical abstract Blow fly pupae were extracted prior to emerging as adults. The extracts were analyzed via total vaporization solid-phase microextraction (TV-SPME), revealing a complex mixture of lipids that could be associated with the age of the insect. This information may assist in determining a post-mortum interval (PMI) in a death investigation.

Association between level of HbA1c and lipid profile in T2DM patients attending diabetic OPD at BPKIHS

Hyperglycemia, dyslipidemia and coronary artery disease relate well with each other in type 2 diabetes and it has been proposed that higher prevalence of cardiovascular disease in type 2 diabetes is due to chronic uncontrolled hyperglycemia. Our study aimed to find utility of Hba1c as indicator of dyslipidemia in patients with type 2 diabetes mellitus. We enrolled 168 T2DM patients in our study and collected venous blood samples in both plain and EDTA vials after a fast of minimum 8 hours. Biochemical analysis was done in fully automated analyzer cobas c311. HbA1c was found to have significant positive correlation with total cholesterol, LDL-C, and triglyceride and significant negative correlation with HDL-C and HDL/LDL ratio. The mean value of TC, LDL-C and TG was found to be lower in patients with good glycemic control than those with poor glycemic control. But, mean value of HDL and HDL/LDL ratios were found to be higher in patients with good glycemic control than those with poor glycemic control. These differences were significant at the level of p &lt;0.05. Our study suggests additional use of HbA1c as indicator of dyslipidemia.Health Renaissance 2015;13 (3): 16-23

Dual centrifugation – A new technique for nanomilling of poorly soluble drugs and formulation screening by an DoE-approach

The development of nanosuspensions of poorly soluble APIs takes a lot of time and high amount of active material is needed. In this publication the use of dual centrifugation (DC) for an effective and rapid API-nanomilling is described for the first time. DC differs from normal centrifugation by an additional rotation of the samples during centrifugation, resulting in a very fast and powerful movement of the samples inside the vials, which − in combination with milling beads − result in effective milling. DC-nanomilling was compared to conventional wet ball milling and results in same or even smaller particle sizes. Also drug concentrations up to 40% can be processed. The process is fast (typical 90min) and the temperature can be controlled. DC-nanomilling appears to be very gentle, experiments showed no change of the crystal structure during milling. Since batch sizes are very small (100–1000mg) and since 40 sample vials can be processed in parallel, DC is ideal for the screening of suitable polymer/surfactant combinations. Fenofibrate was used to investigate DC-nanomilling for formulation screening by applying a DoE-approach. The presented data also show that the results of DC-nanomilling experiments are highly comparable to the results obtained by common agitator mills.

Detection of magnetic nanoparticles with a large scale AC superconducting susceptometer

Magnetic nanoparticles (MNPs) are being used in several applications in medicine such as hyperthermia, magnetic particle imaging, in vitro and in vivo bioassay, and still there are many other possibilities for use of these particles to come as research progress in this field. One crucial step of its use is the detection of these particles when present in a certain tissue. For in vitro bioassay, the sample can be harvested and placed inside the detector in optimal conditions to favor sensitivity. However, for in vivo human measurements the system must be noninvasive and conform to the anatomic restrictions requiring sensitive detectors and dedicated setups. In this study, we detect nanoparticles with an AC biosusceptometer having an excitation homogeneous magnetic field with 145 μT, provided by a set of rectangular large Rubens coils driven at 10 Hz. The magnetization induced in the sample was detected by a second-order axial gradiometer (20 mm in diameter and 40 mm of baseline) coupled to an RF Superconducting Quantum Interference Device (SQUID) model 330X (BTi). The MNPs used were manganese ferrite-based surface-coated with citric acid dissolved in water at various concentrations. The colloid is stable at physiological conditions. X-ray diffraction confirmed the spinel structure and using Scherrer’s relation revealed a particle size of 17.3 nm. The magnetization curve showed a typical superparamagnetic behavior with a specific saturation magnetization of 51.2 emu g−1. The stock solution of nanoparticles had a concentration of 23.17 mg ml−1, corresponding to 1.7 × 1015 NPs ml−1. Measurements were made in a volume of 30 ml with 20 × 103–100 × 103 dilutions of the stock solution of nanoparticles and performed at distances of 1.1, 1.5 and 2.5 cm from the top of the sample vial to the closest coil of the gradiometer. The limits of detection were 8.1 × 109 NP ml−1, 9.5 × 109 NP ml−1 and 11.0 × 109 NP ml−1 for the distances above. These values suggest that the technique might have interesting applications in the real-time in vivo detection of nanoparticles after systemic injections. The present setup can be improved by using more sensitive SQUID sensors and less noisy cryostats.

Quantification of anhydride groups in anhydride-based epoxy hardeners by reaction headspace gas chromatography.

We demonstrate a reaction headspace gas chromatographic method for quantifying anhydride groups in anhydride-based epoxy hardeners. In this method, the conversion process of anhydride groups can be realized by two steps. In the first step, anhydride groups in anhydride-based epoxy hardeners completely reacted with water to form carboxyl groups. In the second step, the carboxyl groups reacted with sodium bicarbonate solution in a closed sample vial. After the complete reaction between the carboxyl groups and sodium bicarbonate, the CO2 formed from this reaction was then measured by headspace gas chromatography. The data showed that the reaction in the closed headspace vial can be completed in 15min at 55°C, the relative standard deviation of the reaction headspace gas chromatography method in the precision test was less than 3.94%, the relative differences between the new method and a reference method were no more than 9.38%. The present reaction method is automated, efficient and can be a reliable tool for quantifying the anhydride groups in anhydride-based epoxy hardeners and related research.

Evaluation of a Freezer Mill for Bone Pulverization prior to DNA Extraction: An Improved Workflow for STR Analysis.

Traditional methods for bone pulverization typically generate heat, risking stability of DNA sample. SPEX™ has developed cryogenic grinders which introduce liquid nitrogen to cool the sample and aid in the grinding process. In this study, the Freezer Mill 6970 EFM was used with two DNA extraction methods and routine downstream STR analysis procedures. DNA from as little as 0.1 g of bone powder was used to develop full STR profiles after freezer mill pulverization, and the method was reproducible. Further, no contamination was detected upon cleaning/reuse of the sample vials. There were no significant differences in DNA yield, STR alleles detected, or peak heights using the freezer mill as compared to traditional grinding, and successful DNA profiles were achieved from as low as 0.1 g of bone powder with this method. Overall, this work indicates that this cryogenic mill method may be used as a viable alternative to traditional tissue grinders.