Giving preparative thin layer chromatography some tender loving care

Preparative thin layer chromatography (prepTLC) is a commonly used method of purification suitable for small scale reactions. However, descriptions of the preferred methodology to load, run, and recover samples from prepTLC are non-standard and varied, making it part of the “hidden curriculum” of laboratory technique. In this article we report on the simple, cost-effective methods we use to load and collect samples from a plate, which enhance the convenience, speed, and precision of this technique.

DETERMINATION OF SOIL TROPHICITY BY ELECTROPHYSICAL METHOD. MESSAGE 1. DEVICE AND LABORATORY TECHNIQUE

The purpose of this work was to develop a device and technique for determining the soil trophiсity using the electrophysical method based on the measurement of the soil specific resistivity (SR). In the proposed device the F. Wenner installation is used as a sensor. The device has a modular design and includes a voltage boosting module, a PWM generator of rectangular pulses, a rectangular signal inverter and an H-bridge that switches the polarity of the power supply in order to prevent polarization of the electrodes. The metrological characteristics of the specific resistivity measurement as well as the influence of the electrodes immersion depth in the substrate studied are determined. Its significant influence and nonlinear character which was well approximated by the power function were established. The simplest equations for bringing the measured values of the RS to a certain depth of the electrodes in the object studied are proposed.

Laboratory technique and methods of expressing the concentration of solutions

The manual is intended for laboratory studies and the organization of independent research work of students of biological and environmental directions of universities. Can be used by teachers and students of educational institutions. Recommended for publication by the educational and methodological council of the Vitus Bering Kamchatka State University for students studying in the direction of training 06.03.01 "Biology".

Which laboratory technique is used for the blood sodium analysis in clinical research? A systematic review

Background Circulating sodium is analyzed by flame spectrometry and indirect or direct potentiometry. The differences between estimates returned by the three techniques are often relevant. It is unknown whether peer-reviewed international publications focusing on this parameter provide information about the technique. Objectives of the study were to ascertain if information about the employed technique is provided. Content A search in the National Library of Medicine for articles whose title contains “hyponatr[a]emia” was performed. We restricted the search to clinical reports including 10 or more humans published in the 2013–2015 and 2017–2019 periods. Authors of papers not reporting the technique were contacted to obtain this information. The study design and journal quartile ranking of each article were also evaluated. Summary For the final analysis, we included 361 articles (2013–2015, n=169; 2017–2019, n=192). Information about the laboratory technique was given in 61(17%) articles. Thanks to our inquiry, we collected this information for 116(32%) further reports. Indirect potentiometry was the most frequently used technique, followed by direct potentiometry. Spectrometry was used in a small minority of studies. Study design, journal ranking and study period did not modulate the mentioned frequency. Outlook Most articles focusing on hyponatremia do not provide information on the laboratory technique. This parameter is nowadays analyzed by indirect or, less frequently, direct potentiometry. The figures are similar for high and low impact factor journals and for the 2013–2015 and the 2017–2019 periods. Many authors, reviewers and editors likely assume that the results of this parameter are not influenced by the technique.

Multi-view Protocols

We present a novel adaptation of a typical science laboratory protocol, which we have termed multi-view protocols (MVPs). The purpose of MVPs is to answer and link three common questions asked by students when first learning a laboratory technique: (1) What am I supposed to do? (2) Where and how am I supposed to do it? (3) What exactly am I doing, anyway? The intent of MVPs is to facilitate parallel comprehension of both the physical “movements” of a technique and the theoretical principles behind each step of a protocol. With MVPs, we achieve this through three parallel columns that include a textual description of the protocol, photographs of the protocol being performed in the laboratory space, and an illustrative column that visually depicts the molecular details of the corresponding steps. Variations of MVPs may include having students create one or more of the parallel columns themselves. In the age of near ubiquitous high-resolution camera phones, MVPs are a practical and efficient way to simultaneously teach laboratory method and theory, adaptable to nearly any laboratory protocol.

Innovative technique for analysis of wastewater contaminants using hyperspectral imaging

Accurate, fast, quantitative on-site analysis of wastewater is an environmental necessity. Therefore, we report a quantitative spectroscopic study in order to analyse organic contaminants in wastewater. For this purpose, two spectroscopy-based techniques were utilised and their results are compared. The first technique is ultraviolet/visible (UV/vis) spectrophotometry. This technique is a standard laboratory technique, however, it is inappropriate for working in the field. Besides, the analysis results of the standard laboratory technique display low accuracy in detecting small concentrations of wastewater contaminants such as methylene blue (< 20 ppm). Accordingly, there is a need for another technique to overcome the shortcomings of UV/vis spectrophotometry. Hyperspectral imaging (HSI) combines imaging and spectrometry. HSI works on-site since it is portable and easy to operate. The analysis of the data acquired by HSI showed a higher efficacy in accurately detecting both low (< 20 ppm) and high concentrations (> 50 ppm) of water contaminants such as methylene blue and methyl orange. For verification, Pearson correlation coefficients were computed between the concentration of contaminants and their absorbance for all the operating spectral bands. The results of the two techniques were statistically compared using Bland and Altman’s limit of agreement. This study showed that HSI is potentially a promising technique for the analysis of wastewater contaminants on-site.