Sample Preparation Techniques For Analysis Research Articles

Overview of Liquid Sample Preparation Techniques for Analysis, Using Metal-Organic Frameworks as Sorbents.

The preparation of samples for instrumental analysis is the most essential and time-consuming stage of the entire analytical process; it also has the greatest impact on the analysis results. Concentrating the sample, changing its matrix, and removing interferents are often necessary. Techniques for preparing samples for analysis are constantly being developed and modified to meet new challenges, facilitate work, and enable the determination of analytes in the most comprehensive concentration range possible. This paper focuses on using metal-organic frameworks (MOFs) as sorbents in the most popular techniques for preparing liquid samples for analysis, based on liquid-solid extraction. An increase in interest in MOFs-type materials has been observed for about 20 years, mainly due to their sorption properties, resulting, among others, from the high specific surface area, tunable pore size, and the theoretically wide possibility of their modification. This paper presents certain advantages and disadvantages of the most popular sample preparation techniques based on liquid-solid extraction, the newest trends in the application of MOFs as sorbents in those techniques, and, most importantly, presents the reader with a summary, which a specific technique and MOF for the desired application. To make a tailor-made and well-informed choice as to the extraction technique.

Revisiting the applications of the extraction replica sample preparation technique for analysis of precipitates in engineering alloys

The extraction replica technique is a useful sample preparation method to fabricate transmission electron microscopy samples for subsequent studies of small particles, such as precipitates, in different types of alloys. With other sample preparation methods, such as thin foil fabrication, the surrounding matrix might influence compositional or crystallographic analysis in the TEM. The extraction replica technique omits that problem, as the precipitates are extracted onto a thin, amorphous film (most commonly carbon) and the influence of the matrix is thus eliminated. The replica can be produced in a direct manner, by a two stage-method or in certain cases by the oxide replica method. A variety of precipitates from common engineering alloys including carbides, nitrides, oxides and various intermetallic phases in steels, nickel-, zirconium-, aluminium-, copper-, and magnesium-based alloys, can be extracted and the techniques are summarized in this work. The choice of etchant is crucial for the end result, as is also showcased experimentally in this work. Furthermore, the direct replica and two-stage replica method are directly compared with each other by new experiments on a low alloyed steel and a zirconium alloy. There are indications that the direct method has a greater particle extraction efficiency of smaller particles compared to the two-stage method. Moreover, the direct method also facilitates the analysis of other features, such as grain boundaries, in special cases. • Extraction replicas are used to characterize a variety of particles in engineering materials. • The direct, and two-stage, carbon replica is the most common and versatile type. • The direct replica tends to have a better extraction of small particles. • The direct replica can also reproduce other features, such as grain boundaries. • The choice of etchant is crucial for the end result.

Collection and Identification of Biological Samples Based on Military On-Site Detection Devices

Due to still current biological threats related to the activities of terrorist groups, crisis situations in many regions of the world, as well as cyclical epidemics, fast and reliable detection of biological contamina-tion is an essential element of ensuring broadly understood safety of the population. The work deals with the sampling and verification procedures. This paper focuses on sample preparation techniques for analysis and details analytical methods for identifying biological agents. Additionally, on-site technologies implemented in military devices for the detection of biological contamination were discussed. The work enables the reader to get acquainted with modern techniques of detection of factors of biological origin and their identification, which is the knowledge necessary when choosing the appropriate equipment depending on the purpose of the contamination recognition sub-unit and the task at hand. Knowledge of sam-pling and preparation of samples for analysis will help to increase the skills of the sampling teams to do so and to achieve reliable results by using appropriate procedures and eliminating the possibility of loss of the analyte or inadvertent contamination of the sample. It will also increase safety at every stage of working with biological samples. All these activities can contribute to the global increase in security of the population around the world. Keywords: chemical sciences, biological weapon, bioterrorism, CBRN, PCR, UV-LIF

Distribution of rare earth and selected trace elements in combustion products of Yerkovetskoe brown coal deposit (Amur Region, Russia)

Major, trace, rare-earth elements, and noble metal have been analyzed from the brown coal of the Amur region (Russian Federation) and coal combustion products to understand the provenance and depositional environment. It was discussed that weathering crusts of ore deposits and host rocks located in the mountain-folded frame of the Zeya–Bureya coal-bearing sedimentary basin were the main source of mineral substance and chemical elements in brown coals. The distribution of minerals and elements inside the forming coal seams was influenced by the type of vegetation incorporated into coal-forming peat mires bog by catastrophic floods along the existed hydraulic network, the physicochemical parameters of plant debris transformation during their conversion to coal, as well as the sorption properties of inclusions and interlayer of bitumen and humic acids in coal beds. An experimental technological complex was created to study the microelements transfer process in the dust–gas stream and the distribution of rare earth and trace elements separately in varieties of coal combustion products (slag, fly ash, dust-like part of the dust–gas flow, and technogenic cleaning water). The resulting combustion products of coal have been studied by inductively coupled plasma (ICP)-spectrometry methods (ICP-mass spectrometry and ICP-atomic emission spectroscopy). Sample preparation technique for analysis was improved to determine the elemental composition. It was established that more than 60% of trace and rare earth elements were concentrated in ash and sludge. Data on these elements’ concentration in the wash water sediment demonstrated a sufficiently high efficiency of the dust–gas flow cleaning. The use of a wet scrubber, of course, solves the problem of collecting the dust and gas flow cleaning from harmful and toxic elements of coal smoke, which should be a part of the technological chain of a coal combustion process in industrial boilers. Rare earth elements, scandium, and yttrium are considered economically valuable components in the coal combustion products of the Yerkovetskoe brown coal deposit in the Amur Region.

Determination of tramadol hydrochloride in water samples by directly suspended droplet three-phase liquid phase microextraction with tetrathiocyanato cobalt(II) as the complexing agent using UV-spectroscopy

Suspended droplet three-phase liquid microextraction is a relatively new sample preparation technique for analysis of drugs. In the current study, tramadol hydrochloride was determined using tetrathiocyanato cobalt(II), (NH4)2[Co(SCN)4], as the complexing agent. The maximum of absorption for the formed ternary complex between tramadol hydrochloride and tetrathiocyanato cobalt(II) was observed at 625 nm. In this method, the target compound was extracted from the aqueous phase (5 mL containing 5 μg/mL of sample, pH 11) into an organic phase and then back-extracted into a directly suspended droplet as acceptor phase (3 μL of 1.74 × 10–9 M tetrathiocyanato cobalt(II), pH 2.8). 1-Octanol was used as organic phase. Under the optimized conditions: extraction time 90 s, back-extraction time 8 min and stirring rate 750 rpm, the linear range, the relative standard deviation (RSD, n = 5) and the limit of detection for tramadol hydrochloride were found 0.5–8 μg/mL, 4.9% and 8 ng/mL (n = 5), respectively. Also, the tap water and surface water samples were successfully analyzed using the proposed method and the relative recoveries obtained from the spiked water samples were 98.2 and 97.6%, respectively.

Development of a MALDI two-layer volume sample preparation technique for analysis of colored conidia spores of Fusarium by MALDI linear TOF mass spectrometry

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been proved to be a powerful tool for the identification and characterization of microorganisms based on their surface peptide/protein pattern. Because of the complexity of microorganisms, there are no standardized protocols to acquire reproducible peptide/protein profiles for a broad range of microorganisms and for fungi in particular. Small variations during MALDI MS sample preparation affect the quality of mass spectra quite often. In this study, we were aiming to develop a sample preparation method for the analysis of colored, a quite often observed phenomenon, and mycotoxin-producing Fusarium conidia spores using MALDI-TOF MS. Different washing solvent systems for light- and deep-colored (from slightly orange to red-brown) conidia spores and connected sample deposition techniques were evaluated based on MS reproducibility and number and intensities of peaks. As a method of choice for generation of reproducible and characteristic MALDI-TOF mass spectra, the use of a washing process for colored Fusarium conidia spores with acetonitrile/0.5% formic acid (7/3) was found and subsequently combined with two-layer volume technique (spores/matrix (ferulic acid) solution was deposited onto a MALDI target, and after solvent evaporation, a second matrix layer was deposited). With the application of this sample preparation method, for deep-colored Fusarium species, 19 abundant molecular ions in the m/z range 2,000-10,000 were always detected with an S/N ratio of 3:1 or better. Finally this optimized sample preparation for the first time provided mass spectrometric fingerprints of strongly colored Fusarium conidia spores resulting in the possibility of differentiation of such spores at the species level.