Laboratory Glassware Research Articles

Analysis, fate studies and monitoring of the antifungal agent clotrimazole in the aquatic environment

The analysis and presence of clotrimazole, an antifungal agent with logK(OW) > 4, was thoroughly studied in the aquatic environment. For that reason analytical methods based on gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry were developed and validated to quantify clotrimazole with limits of quantification down to 5 and 1 ng/L, respectively. Both methods were compared in an intercalibration exercise. The complete mass-spectrometric fragmentation pattern could be elucidated with the aid of quadrupole time of flight mass spectrometry. Since clotrimazole tends to adsorb to laboratory glassware, studies on its adsorption behaviour were made to ensure the appropriate handling of water samples, e.g. pH, storage time, pretreatment of sampling vessels or material of the vials used for final extracts. The phenomena of adsorption to suspended matter were investigated while analysing different waste-water samples. Application of the methods in various investigated wastewater and surface water samples demonstrated that clotrimazole could only be detected in the low nanogram per litre range of anthropogenic influenced unfiltered water samples after acidification to pH 2.

Solid-state multinuclear magnetic resonance investigation of Pyrex®

Pyrex® is an ubiquitous material that has attained widespread use in laboratory glassware and household utensils due to its properties, cost effectiveness, and ease of fabrication. Despite its importance, the structure of borosilicate glass such as Pyrex® is not fully understood. Here, we report high resolution 29Si, 27Al, and 11B magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic measurements at 9.4 and 19.5T, combined with 27Al and 11B multiple-quantum MAS (MQ-MAS), and 11B Rotor Assisted Population Transfer (RAPT), to identify structural features in Pyrex®. A distribution of Q4 silicon and aluminum sites is observed, and there is no evidence of five or six coordinated aluminum. The 27Al quadrupolar coupling constants for the tetrahedral aluminum varied from 3.5 to 4.5MHz, while the isotropic chemical shifts varied from 50 to 65ppm. Boron-11 measurements resolve four distinct distributions in boron environments: two identified as tetrahedral, BO4, and two as trigonal, BO3. Tetrahedral sites are distinguished by different second coordination spheres, e.g., BO4(0 B, 4 Si) and BO4(1 B, 3 Si), and the trigonal sites based on the symmetry of the boron environments.

The Origin of Pyrex

In response to a reader query, the column traces the origins of Pyrex and laboratory glassware in general.

Diethylaminosulfur Trifluoride (DAST)

Fluorination is an important structural modification for ­diverse classes of bioactive organic molecules. The introduction of a fluorine atom or fluorinated group into organic molecules often changes their physical, chemical and physiological properties, resulting in greater stability and lipophilicity of the molecule. [1] Diethylaminosulfur trifluoride (DAST) is a widely used fluorinating reagent, [2-6] which is very effective for converting alcohols, ketones, aldehydes and carboxylic acids into their corresponding fluoro derivatives. This reagent has its origins in the ­pioneering work of Middleton et al. at DuPont. [7] DAST is synthesized via the substitution of a fluorine atom of ­sulfur tetrafluoride (SF4) by a diethylamino group, resulting in a powerful fluorination agent (Scheme 1). DAST presents the following advantages: the product is rela­tively easy to handle and shows good selectivity, con­sequently being less prone to formation of olefins in elimination reactions and/or rearrangement reactions. This reagent is commercially available as liquid that can be handled at room temperature and in common laboratory glassware. However, DAST is unstable above 70 °C.

Trace Analysis of Bromate, Chlorate, Iodate, and Perchlorate in Natural and Bottled Waters

A simple and rapid method has been developed to simultaneously measure sub-microg/L quantities of the oxyhalide anions bromate, chlorate, iodate, and perchlorate in water samples. Water samples (10 mL) are passed through barium and hydronium cartridges to remove sulfate and carbonate, respectively. The method utilizes the direct injection of 10 microL volumes of water samples into a liquid chromatography-tandem triple-quadrupole mass spectrometry (LC-MS/MS) system. Ionization is accomplished using electrospray ionization in negative mode. The method detection limits were 0.021 microg/L for perchlorate, 0.045 microg/L for bromate, 0.070 microg/L for iodate, and 0.045 microg/L for chlorate anions in water. The LC-MS/MS method described here was compared to established EPA methods 300.1 and 317.1 for bromate analysis and EPA method 314.0 for perchlorate analysis. Samples collected from sites with known contamination were split and sent to certified laboratories utilizing EPA methods for bromate and perchlorate analysis. At concentrations above the reporting limits for EPA methods, the method described here was always within 20% of the established methods, and generally within 10%. Twenty-one commercially available bottled waters were analyzed for oxyhalides. The majority of bottled waters contained detectable levels of oxyhalides, with perchlorate < or = 0.74 microg/L, bromate < or = 76 microg/L, iodate < or = 25 microg/ L, and chlorate < or = 5.8 microg/L. Perchlorate, iodate, and chlorate were detectable in nearly all natural waters tested, while bromate was only detected in treated waters. Perchlorate was found in several rivers and reservoirs where itwas not found previously using EPA 314.0 (reporting limit of 4 microg/L). This method was also applied to common detergents used for cleaning laboratory glassware and equipmentto evaluate the potential for sample contamination. Only chlorate appeared as a major oxyhalide in the detergents evaluated, with concentrations up to 517 microg/g. Drinking water treatment plants were also evaluated using this method. Significant formations of chlorate and bromate are demonstrated from hypochlorite generation and ozonation. From the limited data set provided here, it appears that perchlorate is a ubiquitous contaminant of natural waters at trace levels.

Laboratory ventilated sink use for glassware cleaning: Design, installation, and evaluation

Numerous methods for cleaning laboratory glassware are currently available. Existing analytical method constraints at Roche Colorado Corporation (RCC), a Responsible Care company, limit the use of dishwashers and other automated glassware cleaning systems. Therefore, solvent-based laboratory glassware cleaning is performed to remove interfering residues, and represents an area of potential occupational exposure to chemicals. Typical cleaning steps include an initial solvent wash, soap and water cleansing, and a final solvent rinse to dry the glassware. Acetone, a common solvent used for this purpose, has an American Conference of Governmental Industrial Hygienist (ACGIH) TLV-TWA (8 hr) of 500 ppm and TLV-STEL (15 min) of 750 ppm. Exposure monitoring during glassware cleaning indicated that airborne concentrations of acetone may exceed these occupational exposure limits (OELs). To address the potential exposure to acetone vapors, engineering controls, consisting of a custom countertop slotted sink hood and an in-sink downdraft system, have been designed and implemented. Field validation indicated that both ventilated sinks were effective at controlling airborne acetone concentrations well below acetone's OELs.

Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates

Four methodologies for determining the asphalt content of mixtures containing high-loss aggregates in the ignition furnace were evaluated: the standard method using the Thermolyne furnace (control), the Troxler NTO infrared furnace, the Ontario method, and a Tempyrox glass-cleaning oven. Six aggregate sources with high ignition furnace aggregate corrections were obtained from around the country: four dolomites, a basalt, and a serpentine/chlorite. Calibration factors were determined for each method at optimum asphalt content. Additional samples were then tested at optimum plus 0.5% asphalt content, and the measured asphalt content was calculated by using the correction factor determined for that method and aggregate source. The Tempyrox Pyro-Clean furnace, commonly used for cleaning laboratory glassware, produced the lowest aggregate correction factors. The standard method and the Ontario method, both using the Thermolyne ignition furnace, produced the smallest bias or error in measured asphalt content. The standard deviation of the corrected asphalt contents for these high-loss sources was higher than the within-laboratory standard deviation reported for AASHTO T308. The only exception was the Alabama source using the standard method. The Ontario method and Tempyrox oven generally reduced the variability of asphalt content measurements for high-loss aggregates. None of the methods evaluated statistically reduced aggregate breakdown on the nominal maximum aggregate size and 4.75-mm sieves. The Ontario method significantly reduced, but did not eliminate, aggregate breakdown on the 0.075-mm sieve. The Ontario method is the best method for immediate implementation for determining the asphalt content by the ignition method for high-loss aggregates.

Refinement of the Hot-Mix Asphalt Ignition Method for High-Loss Aggregates

Four methodologies for determining the asphalt content of mixtures containing high-loss aggregates in the ignition furnace were evaluated: the standard method using the Thermolyne furnace (control), the Troxler NTO infrared furnace, the Ontario method, and a Tempyrox glasscleaning oven. Six aggregate sources with high ignition furnace aggregate corrections were obtained from around the country: four dolomites, a basalt, and a serpentine/chlorite. Calibration factors were determined for each method at optimum asphalt content. Additional samples were then tested at optimum plus 0.5% asphalt content, and the measured asphalt content was calculated by using the correction factor determined for that method and aggregate source. The Tempyrox Pyro-Clean furnace, commonly used for cleaning laboratory glassware, produced the lowest aggregate correction factors. The standard method and the Ontario method, both using the Thermolyne ignition furnace, produced the smallest bias or error in measured asphalt content. Th...

Tellurium‐Mediated Cycloaromatization of Acyclic Enediynes under Mild Conditions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium‐Catalyzed Carbonylation of Polychlorinated Pyridines. A Simple Laboratory Approach to Metal Catalyzed Carbonylation Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tellurium-mediated cycloaromatization of acyclic enediynes under mild conditions.

The cycloaromatization of acyclic enediynes typically requires very high temperatures (>160 degrees C) and dilute conditions to proceed in a synthetically useful yield. These conditions hinder reaction throughput, inhibiting the use of this reaction for the large-scale production of materials. The reaction of sodium telluride with acyclic arenediynes yields the corresponding tellurepine, which under gentle heating extrudes Te degrees to yield the cycloaromatization product. We have developed conditions that form sodium telluride from inexpensive tellurium metal in situ, and that also perform the desilylation of silylated arenediynes in the same process. Under our conditions, we are able to perform desilylation and cycloaromatization at temperatures as low as 40 degrees C and on a scale as large as 5 g in standard laboratory glassware.

Palladium-catalyzed Carbonylation of Polychlorinated Pyridines. A Simple Laboratory Approach to Metal Catalyzed Carbonylation Reactions

The palladium-catalyzed carbonylation reactions of pentachloropyridine and 2,3,4,5-tetrachloropyridine were investigated in alcoholic or aqueous solvent. The high boiling alcohol 2-ethyl-1-hexanol was an effective carbonylation solvent above 100 °C at 1 atm of CO, representing a convenient and simple method for carrying out transition metal catalyzed carbonylation reactions using standard laboratory glassware.

Heat recovery from a thermal energy storage based on the Ca(OH) 2/CaO cycle

Thermal energy storage is very important in many applications related to the use of waste heat from industrial processes, renewable energies or from other sources. Thermochemical storage is very interesting for long-term storage as it can be carried out at room temperature with no energy losses. Dehydration/hydration cycle of Ca(OH) 2/CaO has been applied for thermal energy storage in two types of reactors. One of them was a prototype designed by the authors, and in the other type conventional laboratory glassware was used. Parameters such as specific heats, reaction rate and enthalpy, mass losses and heat release were monitored during cycles. Although in the hydration step water is normally added in vapour phase, liquid water, at 0 °C has been used in these experiences. Results indicated that the energy storage system performance showed no significant differences, when we compared several hydration/dehydration cycles. The selected chemical reaction did not exhibit a complete reversibility because complete Ca(OH) 2 dehydration, was not achieved. However the system could be used satisfactorily along 20 cycles at least. Heat recovery experiments showed general system behaviour during the hydration step in both types of reactors. The designed prototype was more efficient in this step. Main conclusions suggested carrying out one complete cycle at a higher dehydration temperature to recover total system reversibility. A modification of the prototype design trying to enhance heat transfer from the Ca(OH) 2 bed could also be proposed.

Investigation of adsorption by thermal lensing

Thermal lensing was used for the characterization of adsorption on laboratory glassware at a nanogram concentration level in solution. Sorption kinetics was studied, the sorption capacity of the glass for test substances was characterized, which was found to be several ng cm−2. Factors affecting adsorption were discussed. A procedure for handling laboratory glassware for eliminating sorption effects in determining nanogram amounts of iron in aqueous solutions was developed.

Studying the Adsorption of an Iron(II) Complex of 1,10-Phenanthroline on Laboratory Glassware Using Thermal Lens Spectrometry

The adsorption of iron(II) tris(1,10-phenanthroline) on the glass surface of laboratory ware from solutions has been studied by thermal lens spectrometry at a level of nanogram amounts. The effect of glass pretreatment on the fraction of the adsorbed substance has been studied, and the most appropriate variant of the pretreatment has been selected. The kinetics of iron(II) tris(1,10-phenanthroline) adsorption on the surface of laboratory glass has been studied, and an adsorption isotherm has been constructed for nanogram chelate contents of the solution. The process is most closely approximated by the Freundlich equation. Based on the obtained data, a procedure has been proposed for the preparation of solutions for constructing calibration relationships that can be used in thermal lens measurements of trace amounts of analytes. This procedure takes into account the loss of substances at the surface of laboratory glassware.

Calcium sulfate (gypsum) scaling in nanofiltration of agricultural drainage water

Reclamation and reuse of agricultural tile drainage water in the San Joaquin Valley, California, by membrane desalination has been given serious consideration for nearly 30 years. The agricultural drainage water has very high levels of calcium and sulfate ions, rendering it nearly saturated with gypsum in some locations in this region. The present paper focuses on the conditions of membrane surface gypsum scale formation during nanofiltration (NF) of agricultural drainage water. Experimental studies with drainage water samples and model solutions were conducted in laboratory glassware as well as with a small plate-and-frame cross-flow membrane re-circulation unit. NF membrane experiments consisted of two types: permeate disposal to measure the effect of increasing recovery on the onset of scaling, and feed water re-circulation at a fixed concentration factor to establish performance change over time. An expression relating NF product water recovery to feed water concentration factor enabled numerous membrane scale formation studies that have direct relevance to full-scale NF systems. Glassware experiments showed that magnesium ions decreased the amount of gypsum incipient nuclei because of MgSO 4 0 complexation, which reduces the availability of sulfate ions for nucleus formation. In membrane experiments, model solutions showed that bicarbonate, magnesium ions, and humic acid retarded the onset of gypsum scaling by tying up calcium ions that would have otherwise been used for formation of gypsum incipient nuclei. Both calcium carbonate and gypsum scales may result from particulate deposition rather than membrane surface (wall) crystallization, with the likelihood of particulate fouling increasing with supersaturation.

Investigation of adsorption of nanogram quantities of iron(II) tris-(1,10-phenanthrolinate) on glasses and silica by thermal lens spectrometry

Thermal lens spectrometry is used for studying adsorption equilibria in aqueous solutions at the level of nanogram quantities of iron(II) tris-(1,10-phenanthrolinate) as a model system. The kinetics of the sorption of the chelate on silica is studied and adsorption isotherms are built. Thermal lensing is used as a method for direct determination of the chelate concentration adsorbed on a quartz surface. The detected amount is 4.1×10 −15 mol at the area irradiated by the excitation beam. The adsorption of iron(II) tris-(1,10-phenanthrolinate) on laboratory glassware at the nanogram level is characterised by measuring the residual concentration of the sorbate in solution. A procedure for handling and cleaning the laboratory glassware for determining nanogram amounts of iron in aqueous solutions is proposed. The sensitivity of thermal lensing both in measuring adsorption on silica and glass and quartz surfaces is 100-fold higher than diffuse-reflectance measurements under the same conditions.

Managing the Workflow of a High-Throughput Organic Synthesis Laboratory: A Marriage of Automation and Information Management Technologies

The production of high quality, individually characterized libraries of compounds requires a well-developed strategy, along with robust, user-friendly data and automation systems to support this strategy. We developed a workflow process to improve the efficiency of producing greater than 50,000 individual compounds per year. Our workflow process eliminates bottlenecks in traditional procedures and thus ensures a steady, predictable compound production rate. Initially, virtual library creation allowed for the determination of the physio-chemical properties of libraries as well as the ability to calculate the needed amounts of reagents and solvents for a production campaign. At this point, we registered all samples into our library database. Production of libraries began with loading the appropriate linkers onto resins, followed by complete characterization of the resin-linker intermediate. The resins were then loaded into IRORI MiniKans™ and sorted using the IRORI Autosort™ 10Kx sorting workstation. Chemistry was then performed using standard laboratory glassware. Additional sorting and chemistry steps were then performed until the compound was ready for cleavage off of the resin. The MiniKans were then sorted into Bohdan MiniBlocks™ and treated with the appropriate cleavage cocktail. Collection into 48-position racks was followed by removal of cleavage solution through vacuum centrifugation. The concentrate was then dissolved in a solvent mixture that allowed for standard liquid handling automation to create 96 well plates for analysis by high throughput flow inject NMR and LC/MS. Compounds 80% pure by LC/MS and presenting a &gt;80% overall yield, as determined by NMR, were automatically flagged “acceptable” in the database. Compounds that failed to pass these analytical criteria were flagged “fail” in the database and were examined for trends that could be corrected in future library production. Finally, acceptable compounds were reformatted from the original source plates into master plates.

Safety practices with laboratory glassware

Safety practices with laboratory glassware

Ceramic innovations in the 20th century

Ceramic innovations in the 20th century