Cleaning Of Glassware Research Articles

Laboratory Glassware Cleaning Validation by Liquid Chromatographic Quantitation of Betamethasone Valerate Residues

Use of clean glassware ensures reliability of analyses that are carried out in laboratories. Glassware should be free of contaminants and residues from previous tests. It is therefore necessary to demonstrate the efficiency of glassware cleaning procedure through validation. This study aims to evaluate the cleaning efficiency of laboratory glassware by quantitation of betamethasone valerate residues in cleaned glassware. Betamethasone ointment was selected through a risk ranking process as the worst to clean product. Glassware used in analysis of this drug product was cleaned manually and residues evaluated using high performance liquid chromatography. The analysis method was validated at concentration levels of 1 - 8 µg/ml for specificity, accuracy, precision, linearity, limit of detection and limit of quantitation. The method demonstrated residue recovery of 97%. Repeatability and inter-mediate precision expressed as relative standard deviation were 1.2% and 1.4%, respectively. The calibration curve was linear over a concentration range from 2.04 to 6.13 µg/ml with a correlation coefficient of 0.9997. The detection limit and quantitation limit were 0.11 µg/ml and 0.34 µg/ml, respectively. No residue was detected in glassware that was sampled for the cleaning validation. The results indicate that the manual cleaning method is effective as the level of betamethasone residues in cleaned glassware was below detection limit and thus will not interfere with analysis of the subsequent analyte.

Contribution to the determination of tributyltin in water by stir bar sorptive extraction‒thermal desorption‒gas chromatography‒tandem mass spectrometry

An environmentally friendly method was developed to determine tributyltin (TBT) in water at the levels required by the European Union Water Framework Directive (EU WFD) using stir bar sorptive extraction (SBSE) in combination with thermal desorption‒gas chromatography‒triple quadrupole tandem mass spectrometry. The main focus of the method development was on addressing some aspects of reducing blank values (minimizing the use of chemicals, glassware cleaning, pretreatment of sorptive stir bars) and optimizing the SBSE procedure variables (sample volume, polarity of sample solution, extraction time). The performance of the method was studied in terms of linearity, matrix effect, method limits and accuracy (precision and trueness) using MilliQ, tap and surface water. TBT quantification limit for the studied matrices ranged from 0.049 to 0.055 ng L‒1 and repeatability (RSD%, n = 10) and recovery at the environmental quality standard (EQS) concentration of 0.2 ng L‒1 were in the range of 6‒18% and 88‒107%, respectively, indicating good performance of the method. The matrix effect of river water (‒78%) and artificial seawater (‒83%) compared to MilliQ water showed the necessity to use a matrix-matched calibration when analysing TBT in surface water samples. The developed sample preparation was further evaluated for greenness using the recently introduced AGREEprep assessment, which revealed a much greener performance of the proposed method over the compared CEN/TS 16692 method. The method meets the requirements of the EU WFD and is suitable for monitoring, evaluation and classification of the chemical status of surface waters.

Provision conditions for increasing the reliability of trace analysis of toxic metals

Introduction. Heavy metals are included in one of the significant groups of ecotoxicants. Determining heavy metals at low levels is one of the main problems in analytical chemistry, which depends on various factors. Ignoring the contribution of these factors to the total uncertainty can increase the probability of distortion of the results due to an erroneous decision on the compliance of the obtained data with a particular standard. The most significant influences include the purity of reagents, dishes, and air in laboratory rooms. Purpose of the work. Search for ways of reducing the listed influences provided that the expense of time, material and labour resources are minimized. Materials and methods. In the course of the work, many experiments were carried out, including the analysis of nitric acid for the content of metals before and after cleaning by distillation, the analysis of washes from new fluoroplastic laboratory glassware and glassware that had been cleaned by steaming, an assessment of the effect of air pollution in the laboratory room based on a study of calibration curves, which were constructed at the analysis of standard iron solutions prepared in the Clean Workplace and in a conventional fume hood. All measurements were performed by inductively coupled plasma mass spectrometry on Agilent 7800 ICP-MS mass spectrometer. Results. The efficiency of the proposed methods for eliminating interfering influences on the analysis has been experimentally proved. Conclusion. The technical and analytical problem, which consists of finding optimal conditions for preparation of reagents, glassware cleaning and decreasing the influence of laboratory air pollution, allows to increase reliability of the obtained results and prevent distortion of information about the observed degree of environmental pollution.

Glassware cleaning

Glassware cleaning

High efficiencies for laser cleaning of glassware irradiated from the back: application to glassware historical objects

We present a systematic study of laser cleaning of black paint deposited on both standard and frosted glasses. We performed laser cleaning of black paint layers of different thicknesses in both front- and backside laser irradiation geometries. Using laser ablation induced photoacoustics (LAIP), we determined the ablation threshold of the paint that turns out to be independent of the paint thickness and substrate’s properties. To characterize the efficiency of the cleaning process as a function of the number of laser shots, we measured the transmission of the glass in the ablated region and simultaneously the amplitude of the acoustic signal generated by the ablation process. We show that laser cleaning is much more effective when the glass sample is irradiated from the back. To explain this effect, we propose a phenomenological model. This model also predicts the existence of a critical thickness, above which backside cleaning is no longer efficient. The method of back incidence laser cleaning was successfully applied to two real objects, namely a piece of advertising glass covered with black paint and an antique glass bottle with black dirt inside, both archeological objects founded in excavations made in the city of Buenos Aires.

Evaluating the blank contamination and recovery of sample pretreatment procedures for analyzing organophosphorus flame retardants in waters

Organophosphate esters (OPEs), used as flame retardants and plasticizers, are widely present in environmental waters. Development of accurate determination methods for trace OPEs in water is urgent for understanding the fate and risk of this class of emerging pollutants. However, the wide use of OPEs in experimental materials results in blank interference, which influences the accuracy of analytical results. In the present work, blank contamination and recovery of pretreatment procedures for analysis of OPEs in water samples were systematically examined for the first time. Blank contaminations were observed in filtration membranes, glass bottles, solid phase extraction cartridges, and nitrogen blowing instruments. These contaminations could be as high as 6.4–64ng/L per treatment. Different kinds of membranes were compared in terms of contamination levels left after common glassware cleaning, and a special wash procedure was proposed to eliminate the contamination from membranes. Meanwhile, adsorption of highly hydrophobic OPEs on the inside wall of glass bottles was found to be 42.4%–86.1%, which was the primary cause of low recoveries and was significantly reduced by an additional washing step with acetonitrile. This work is expected to provide guidelines for the establishment of analysis methods for OPEs in aqueous samples.

Creation of Modern Instruments for Glassware Cleaning and Cleanliness Testing

As we all know, glass instrument reactive substances in Physical, chemical experiments, bloom residue attached to the inner wall of the instrument after a chemical reaction, often heated to high temperatures or placed the longer reactive substances glass instrument, but not easy to clean. Use unclean instruments, will affect the experimental results, and even let the experimenter observed error phenomenon, induction, reasoning out the wrong conclusions. Therefore, the chemical experiments using glass instruments must be washed clean. In this paper, by using ordinary scrub, ultrasonic cleaning, using a muffle furnace or oven drying, last extraction air form headspace and using GC-MS to detect it, then you will know glass instrument is thoroughly clean or not.

A visual tutorial on the synthesis of gold nanoparticles

Many papers have been written on the synthesis of gold nanoparticles but very few included pictures of the process, and none of them used video to show the whole process of synthesis. This paper records the process of synthesis of gold nanoparticles using video clips. Every process from cleaning of glassware, an important step in the synthesis of metallic nanoparticles, to the dialysis process is shown. It also includes the preparation of aqua regia and the actual synthesis of gold nanoparticles. In some papers, the dialysis process was omitted, but in this paper, it is included to complete the whole process as it is being used for purification.

Sequential injection analysis for automation of the Winkler methodology, with real-time SIMPLEX optimization and shipboard application

A multipurpose analyzer system based on sequential injection analysis (SIA) for the determination of dissolved oxygen (DO) in seawater is presented. Three operation modes were established and successfully applied onboard during a research cruise in the Southern ocean: 1st, in-line execution of the entire Winkler method including precipitation of manganese (II) hydroxide, fixation of DO, precipitate dissolution by confluent acidification, and spectrophotometric quantification of the generated iodine/tri-iodide (I(2)/I(3)(-)), 2nd, spectrophotometric quantification of I(2)/I(3)(-) in samples prepared according the classical Winkler protocol, and 3rd, accurate batch-wise titration of I(2)/I(3)(-) with thiosulfate using one syringe pump of the analyzer as automatic burette. In the first mode, the zone stacking principle was applied to achieve high dispersion of the reagent solutions in the sample zone. Spectrophotometric detection was done at the isobestic wavelength 466 nm of I(2)/I(3)(-). Highly reduced consumption of reagents and sample compared to the classical Winkler protocol, linear response up to 16 mg L(-1) DO, and an injection frequency of 30 per hour were achieved. It is noteworthy that for the offline protocol, sample metering and quantification with a potentiometric titrator lasts in general over 5 min without counting sample fixation, incubation, and glassware cleaning. The modified SIMPLEX methodology was used for the simultaneous optimization of four volumetric and two chemical variables. Vertex calculation and consequent application including in-line preparation of one reagent was carried out in real-time using the software AutoAnalysis. The analytical system featured high signal stability, robustness, and a repeatability of 3% RSD (1st mode) and 0.8% (2nd mode) during shipboard application.

MATERIAL VEGETAL E AS ROTINAS LABORATORIAIS NOS PROCEDIMENTOS QUÍMICO-ANALÍTICOS

Este texto, objetiva primariamente, atender o corpo discente envolvido em trabalhos acadêmicos, pesquisas científicas, dissertações e teses que, em função do curto período de permanência em suas atividades no curso, carecem de metodologias com desenvolvimento detalhado da rotina de laboratório que os tornem auto-suficientes, em suas análises, a despeito dos vários manuais publicados. O mesmo contém informações básicas sobre limpeza de vidrarias, preparação da amostra e leitura em vários equipamentos. Também mostra didaticamente métodos de determinação de nutrientes em material vegetal, incluindo as transformações matemáticas das leituras, para unidades padronizadas. Descreve, ainda, métodos de obtenção de extratos por digestão via seca – incineração; via úmida – Kjedahl, extrações com ácidos diluídos. Para as leituras das amostras são utilizadas técnicas de titulação, colorimetria, fotometria de emissão e espectrometria de absorção atômica. As referências bibliográficas, utilizadas como leitura complementar, auxiliam no direcionamento dos leitores a dados adicionais no caso de ser necessário um aprofundamento maior. Espera-se que as informações contidas nesse texto auxiliem os operadores na condução de suas análises pertinentes às metodologias explicitadas.

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.

Determination of neutral chlorinated extractable organic compounds in water samples using large volume on‐column injection capillary gas chomatography–mass spectrometry

AbstractAn automated large volume on‐column injection technique (LOCI) for capillary gas chromatography – mass spectrometry, GC‐MS, with solvent divert and heated retention gap technology has been used to simplify the method for determining sixteen neutral chlorinated extractable compounds (NCEC) in industrial plant process water samples at a level of 10 ng/L. According to the simplified procedure, 30 mL of water sample is extracted with 5 mL hexane, and 100 μL of the extract analyzed by combining large volume on‐column injection with mass‐selective detection operated in the selected ion monitoring mode. This combination has enabled simplification of the sample preparation and analysis procedures and provided a fast, labor‐saving technique for analyzing water samples. Simplifications include significant reduction of sample and eluent volumes during extraction, and elimination of the Kuderna‐Danish evaporative concentration step. The latter simplification has not only resulted in significant time savings, both during the analysis and for subsequent glassware cleaning; analyte losses and the introduction of contaminants and artifacts which may occur during this step have also been eliminated.System behavior, e.g. linearity of detector response, method detection limit, and reproducibility, were evaluated for all sixteen analytes using spiked water samples in the lower ng/L range. The response of the mass detector is linear in the range 5–20000 ppt for all sixteen NCEC investigated. Injection of 100 μL of sample using LOCI makes it possible to achieve an instrument detection limit in the ppt range. The calculated method detection limits are similar to those of the instrument precision and are lower than the required method detection limit of 10 ppt.Extraction efficiency has been maximized by optimizing sample‐to‐solvent ratio and extraction time. The extraction efficiency seems to be independent of sample‐to‐solvent ratio in the range of 2. 5 to 6 and increasing the extraction time from 25 to 120 minutes resulted in no significant increase in efficiency. Extraction efficiency also seems to be independent of the concentration of analyte in the water samples. The simplified procedure presented here was automated by means of a laboratory robot and used to generate all the extraction data reported in this manuscript.

A modified distillation method for the detection of fat oxidation in foods

SummaryA rapid distillation procedure for the estimation of fat oxidation in food using the 2‐thiobarbituric acid test has been developed. The apparatus generates steam rapidly and allows high sample throughput while minimizing cleaning of glassware. Using the standard compound, tetramethoxypropane (TMP), and a number of food samples spiked with standard, the recovery of malondialdehyde was determined and suitable operating conditions selected. Levels of TMP equivalent to TBA numbers between 1 and 10 were used. Recovery of standard increased from 25.3% at 20 ml to 81.6% at 120 ml, and recoveries at different TBA numbers were similar. After consideration of various factors, 50 ml was chosen as the distillate volume and was collected in about 4 min. With food samples, the recovery varied depending on the composition of the food and, in order to determine TBA number, it was necessary to calculate recoveries from each type of sample. In the reaction of distillate with thiobarbituric acid, colour development was found to be extremely temperature sensitive, and careful temperature control of the heating bath was required.

Comparison of Steam-Distillation Apparati and Glassware Cleaning Procedures for Reduction of Nitrogen-15 Cross-contamination

Several studies were conducted to evaluate the effectiveness of three types of steam-distillation apparati and condensing columns and various acid-bath cleaning procedures for glassware for reduction of cross-contamination errors after contamination with 50 atom percent excess 15N. Regardless of the procedure used to reduce contamination between samples, a stainless steel apparatus always retained less N than a glass design widely used in N research. However, comparable cross-contamination errors with glass can be achieved by simulating design features that have been recommended for the stainless steel apparatus. The effectiveness of the condensing columns in reducing cross-contamination was in the order: stainless steel > Ag-plated brass > glass where no procedure was performed to reduce cross-contamination. Regardless of the procedure used to reduce contamination, the stainless steel condenser always retained the least amount of N. However, use of a steel condenser in conjunction with a glass steam-distillation head did not reduce cross-contamination errors. Immersion of glassware in 0.01 M HCl for 5 min removed 18 to 80% of residual NH+4-N from contaminated glassware. Longer immersion periods improved contamination errors but did not eliminate residual NH+4-N. Hydrofluoric acid was generally more effective than HCl in removing retained N but offers little advantage during routine N analysis.

Electrolytic Extractions of Precipitates From Steel Alloys

During aging of an iron based alloy, the degree of preparation has significant effects on the properties of the alloy. Long-term heat treatments can produce rather large precipitates. In order to obtain compositional and/or structural information from these large precipitates, it is often necessary to examine them in the absence of the surrounding matrix. However it has been found that the extraction replica technique is reliable only for particles 1 μn in size or less. Any larger particle tends to stay embedded in the matrix. We have found electrolytic extraction from the this bulk to be the only reliable way to obtain precipitate particles larger than 1 um. By modifying a gravimetric-vacuum filter assembly, a new method of extraction has been developed, eliminating the time consuming and laborious steps of centrifuging the electrolyte, retrieval of precipitates from test tubes, vacuum drying, and acid cleaning of glassware.

Determining free available chlorine—round 3

Noting that the article entitled “Determining Free Available Chlorine by DPD‐Colorimetric, DPD‐Steadifac (Colorimetric), and FACTS Procedures” by Cooper et al. (JOURNAL AWWA July 1982) has prompted several letters to the editor, this reader writes to state that the resolution to the controversy is an individual one. Analysts must consider FACTS reagent variability, DPD colorimetric, and glassware cleaning and rinsing as factors in determining free available chlorine using colorimetric and FACTS procedures.

Clean laboratory glassware

This author recommends a glassware cleaning system that has been effective in keeping the glassware used for organic laboratories clean.

An evaluation of the Ceric-Cerous system as an impurity-insensitive megarad dosimeter

Results are given of a study of the rate of cerium (IV) reduction in 60Co gamma irradiated cerium (IV)-cerium (III)-0·4 molar sulphuric acid solutions prepared from water of various purities. At cerium (III) concentrations of 3·1 mmolar and above, the measured dose response was linear over a wide dose range. For any given cerium (III) concentration 3·1 mmolar or above there was no significant difference between the G(Ce 3+) obtained, whether solutions were prepared from water of the highest purity or mains water. Triple distillation of water and special cleaning of glassware are therefore unnecessary in ceric dosimetry if cerium (III) of this concentration is present in the solution and this facilitates routine application of the method. The cerium (III) yield from the solutions is as little affected by increased temperature as that from the traditional ceric dosimeter and photolytic stability is improved slightly. Buildup factors and LET effects need to be taken into account under degraded spectral conditions.

Essentials of Tissue Culture Technique

THIS admirable book should be acquired by everyone who uses the tissue culture technique. It contains delightfully clear and precise descriptions of most of the chief tissue culture methods and the apparatus and laboratory accommodation required, and also deals in great detail with such general matters as the arrangement and ventilation of the laboratory, sterilisation, cleaning of glassware and the preparation of physiological solutions. There is a chapter by C. G. Grand devoted to photomicrography, and the book concludes with four useful appendixes, one of which enumerates the principal pitfalls which the beginner is likely to encounter, and will doubtless prove a boon to many readers. The references to literature are listed in a bibliography and should have been more carefully checked, as at least two of the references to special techniques are wrong. Essentials of Tissue Culture Technique By Gladys Cameron; Illustrations and Chapter on Photomicrography by C. G. Grand. Pp. xvi + 134 + 9 plates. (New York: Farrar and Rinehart, Inc., 1935.) 3 dollars.