Samples Of Different Nature Research Articles

Features of High-Precision Photothermal Analysis of Liquid Systems by Dual-Beam Thermal Lens Spectrometry.

Thermal lens spectrometry is a high-sensitivity method for measuring the optical and thermal parameters of samples of different nature. To obtain both thermal diffusivity and absorbance-based signal measurements with high accuracy and precision, it is necessary to pay attention to the factors that influence the trueness of photothermal measurements. In this study, the features of liquid objects are studied, and the influence of optical and thermal effects accompanying photothermal phenomena are investigated. Thermal lens analysis of dispersed solutions and systems with photoinduced activity is associated with a large number of side effects, the impact of which on trueness is not always possible to determine. It is necessary to take into account the physicochemical properties and optical and morphological features of the nanophase and components exhibiting photoinduced activity. The results obtained make it possible to reduce systematic and random errors in determining the thermal-diffusivity-based and absorbance-based photothermal signals for liquid objects, and also contribute to a deeper understanding of the physicochemical processes in the sample.

Microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for the elemental analysis of complex matrix samples

Microwave induced plasma optical emission spectrometry (MIP-OES) has gained widespread attention in the last few years for trace elemental analysis. Among the new generation of MIPs it is worth to mention the microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for which previous works have shown similar detection capabilities to those afforded by ICP-OES. Nevertheless, this instrument has not been applied yet to complex matrix sample analysis. Therefore, the goal of this work is to evaluate MICAP-OES performance (e.g., analytical figures of merit, matrix effects, etc.) for elemental analysis of samples of different nature (e.g., environmental, food and polymers). To this end, both spectral and non-spectral interferences were investigated for 19 elements (Ag, Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Ga, In, Mg, Mn, Ni, Pb, Sr, Tl, Zn) in the presence of inorganic acid, organic and saline solutions and compared to a 5 % w w−1 HNO3 solution. Unlike previous MIPs, experimental data showed that the optimum nebulizer gas flow rate for a given emission wavelength was mostly independent of matrix characteristics. Regarding matrix effects, this device was highly robust operating both inorganic acid and organic matrices. Interestingly, when operating saline matrices, changes on emission signal by easily ionizable elements were less significant than those early reported by alternative MIP cavities. Moreover, due to MICAP spectrometer design employed allows real-time simultaneous analysis, Rh, Pd, Sc and Y were suitable internal standards to minimize non-spectral interferences. Finally, MICAP-OES can be successfully applied to the elemental analysis of different complex matrix samples (i.e., CRM-DW1 Drinking water; BCR-146 Sewage sludge industrial; BCR-185 Bovine liver; BCR-278R Mussel tissue; NIST-1549 Non-fat milk powder; ERM-EC681k Polyethylene (high level) and BCR-483 Sewage sludge amended soil).

Testing procedures for CO2 uptake assessment of accelerated carbonation products: Experimental application on basic oxygen furnace steel slag samples

Many CO2 reactive by-products from industrial processes can be valorised via carbonation to produce building materials. The amount of CO2 captured in mineralisation processes is environmentally and economically relevant, however results from the literature are often controversial owing to a lack of standardisation in the existing CO2 quantification techniques.In this study testing procedures for the assessment of carbonation efficiency are outlined and applied on basic oxygen steel slag samples providing CO2,uptake estimates ranging from 13.3% to 17.0%. Thermogravimetry, thermal decomposition and acid digestion, emerged as valuable techniques for carbonates quantification that can be adopted on samples of different nature, i.e. powders, pastes and mortars. Advantages and drawbacks of each method are discussed, and their field of application is defined. A comparison of the experimental results with similar studies from the literature is reported as well.

A green methodology for the determination of cocaine in camouflaged samples.

A methodology based on the ultrasound-assisted extraction with ethanol and the dry film attenuated total reflectance infrared spectroscopy (DF-ATR-FTIR) measurement of extracts has been developed for a fast evaluation of non-conventional ("exotic") solid-sized cocaine samples. The method provides quantitative results in less than three minutes with a limit of detection in the solid sample of 1.6 μg g-1 of cocaine with a variation coefficient lower than 7%. Results found for seized samples of different natures were compared with those obtained by a reference gas chromatography method and the greenness of the whole proposed procedure was evaluated and compared using the analytical eco-scale, green analytical procedure index (GAPI), and analytical greenness metric (AGREE). The green evaluation of the proposed methodology provided green scores by considering different evaluation criteria.

LIBS and Raman image fusion: An original approach based on the use of chemometric methodologies

Laser-induced breakdown spectroscopy (LIBS) imaging is a powerful and innovative technique with a constant increasing success and interest in many scientific fields. Using LIBS imaging, it is possible to highlight the presence of atoms in complex samples of different nature to achieve important spectral and spatial information. Simple preparation of the sample, an acquisition rate that can reach a speed of 1 kHz, a high spatial resolution (in the order of μm scale) and a sensitivity in the order of ppm are among the assets of this technique. An additional valuable aspect in the current LIBS setups is the possibility to acquire with the same LIBS platform spectroscopic responses resulting from another radiation-matter interaction, such as Raman measurements. The most common data treatment approach to LIBS imaging data is still univariate, i.e., the observation of maps at certain representative LIBS wavelength, but this prevents extracting all the useful information contained in the acquired spectra and obtaining an integral understanding of the correlation between the spatial and spectral information. Chemometrics and multivariate analysis in the framework of spectral unmixing can lead to these outcomes. Therefore, the aim of this work is to show the potential of investigating simultaneously LIBS and Raman imaging spectral data acquired on the same sample with the assistance of the unmixing method Multivariate Curve resolution – Alternating Least Squares (MCR-ALS). To illustrate the value of the thorough interpretation of fused LIBS and Raman images by unmixing analysis and the steps to take place in this kind of study, a real sample of a complex polymetallic mineral formed by several mineral phases incorporating carbonates, silicates and sulphides has been used. In this paper we will show that using a pipeline analysis already validated in another work of our group, it is possible to extract pure chemical contributions of the heterogeneous aforementioned minerals. The data analysis protocol presented is valid for the investigation of LIBS and Raman spectroscopies separately, but becomes much more valuable when the two acquired data sets for the same sample are simultaneously examined, leading to new aspects that would be hindered if not investigated at the same time with a suitable fusion approach.

A rapid, sensitive, and specific assay to measure TF activity based on chromogenic determination of thrombin generation

BackgroundMost tissue factor (TF) activity assays are based on measurement of factor X (FX) activation by TF in the presence of factor VII (FVII)/FVIIa. This requires long incubation, which may result in TF‐independent activity of FX and inaccurate measurement of TF activity. AimTo develop a sensitive and specific TF activity assay, which does not register a non‐specific TF activity, using commercial coagulation factors. MethodsTissue factor activity was measured based on the ability of TF to accelerate the activation of FX by FVIIa in the presence of factor V (FV)/Va, prothrombin, and phospholipids. Following 4 min incubation at 37°C, TF activity was quantified in test samples of different nature by thrombin generation using a chromogenic substrate. ResultsThe TF activity assay proved high sensitivity (low fM range) and specificity, assessed by neutralization of TF activity by anti‐TF antibody and the use of FVIIai. TF activity was detected in extracellular vesicles (EVs) derived from HAP1‐TF+cells, while no activity was measured in EVs from HAP1‐TF/KO cells. The assay was applicable for measurement of TF activity on the surface of live endothelial cells and monocytes activated in vitro, and cell lysates. Infusion of low dose lipopolysaccharide (2 ng/kg bodyweight endotoxin) caused a transient 8‐fold increase (peaked at 4 h) in TF activity in EVs isolated from plasma of healthy volunteers. ConclusionOur assay provides a fast, sensitive, and specific measurement of TF activity. It reliably quantifies TF activity on cell surface, cell lysate, and isolated EVs. The assay can be used for laboratory and clinical research.

NovADEC: Novel Approach for Determination of the Elemental Content of organic matter

ABSTRACT Organic matter (OM) significantly influences the physico-chemico-biological properties of geomaterials (viz., soils, sediments, municipal solid waste) and hence its accurate determination has profuse applications in agriculture, environmental and geotechnical engineering fields. OM mainly consists of carbon, hydrogen, nitrogen, and oxygen, collectively known as elemental content (EC), and these elements can be determined to estimate OM and its variation in several processes, including decomposition under the actions of thermal and biological activities. Usually, EC is determined by employing an elemental analyser, wherein the sample is exposed to an elevated temperature for the conversion of the elements to their respective gases (viz., CO2, H2O, N2, and NyOx) followed by detection of these gases to quantify the percentage of C, H, N, and O. However, this technique has limitations, including time-consuming process, expertise required for instrument operation, issues related to sample preparation and analysis of heterogeneous materials and the destruction of the analysed specimen. These provided the impetus for the development and validation of a Novel Approach for Determination of the Elemental Content, NovADEC, which employs Fourier-transform infrared (FTIR) spectroscopy and multiple regression analysis (viz., partial least-squares regression), as presented in the present manuscript. To develop NovADEC, five samples of different natures, including geomaterials and two standard materials (viz., cellulose and its derivative), with volatile solids ranging between 13% and 85% have been considered. Further, to create a wide range in ECs, sub-samples were thermally treated at furnace temperatures ranging between 150°C and 700°C. These sub-samples were subsequently analysed by employing elemental analyser and FTIR-spectroscopy techniques. A critical synthesis of the results demonstrates that the NovADEC predictive model facilitates a quick determination of the OM of geomaterials.

Profiling of Organic Compounds in Bioethanol Samples of Different Nature and the Related Fractions.

Forty-one bioethanol real samples and related fractions, together with a biobutanol sample, have been analyzed with gas chromatography coupled to either mass spectrometry (GC–MS) or flame ionization detection (GC–FID). Bioethanol with different water contents, samples originated from several sources of biomass, first- as well as second-generation specimens, distillation fractions, samples stocked in containers made of four different materials, and, finally, a biobutanol sample have been analyzed. The number of the compounds found through GC–MS has been 130, including alcohols, aldehydes, ketones, esters, ethers, nitrogen compounds, organic acids, furane derivates as well as other species (e.g., limonene). Afterward, a quantitative determination of major components of bioethanol has been carried out. The achieved results have revealed that, besides ethanol and, in some cases, water, species such as acetaldehyde, methanol, and higher alcohols, as well as 1,1-diethoxyethane, may be present at concentrations above 500 mg L–1. While the source of bioethanol (nature of the raw material, ethanol generation, or water content) has a direct impact on its volatile organic compound (VOC) profile, the material of the container where the biofuel has been stored does not play a significant role. Finally, the results have demonstrated that, for a given production process, different distillation fractions contain unequal VOC profiles.

Development of a sensitive method for determining traces of prohibited acrylamide in cosmetic products based on dispersive liquid-liquid microextraction followed by liquid chromatography-ultraviolet detection

According to the European Regulation on cosmetic products, the presence of acrylamide in these consumer products is not allowed due to its mutagenic and potentially carcinogenic effects. Despite this ban, acrylamide might be present in those cosmetic products containing acrylamide-based polymers. However, there is no analytical method for its determination in this type of matrices. Based on this, the development of analytical methods for the determination of acrylamide in cosmetic products is required to guarantee consumer safety. In this work, an analytical method for determining traces of prohibited acrylamide in cosmetic products is presented for the first time. The method is based on dispersive liquid-liquid microextraction (DLLME), followed by liquid chromatography–ultraviolet (LC-UV) detection. A previous derivatization of acrylamide with 2-naphthalenethiol was performed to obtain a more lipophilic compound, and therefore, more extractable in the DLLME step, in addition to the bathochromic displacement of the measurement wavelength. The main variables involved in both derivatization and DLLME step were studied to provide the best enrichment factors. Under the optimized conditions, 6.5 mL of aqueous sample solution was cleaned-up from lipophilic matrix components by liquid-liquid extraction (LLE) using 3.5 mL of hexane. Then, 5 mL were taken and subjected to microwave derivatization with a mixture of 250 μL of 2-naphthalenethiol (0.5 mg mL−1) and 250 μL of di-sodium tetraborate (4 mg mL−1). Afterwards, it was subjected to DLLME by injecting a mixture of 250 µL of acetone (as disperser solvent) and 80 µL of chloroform (as extraction solvent). The extracts were evaporated to dryness, reconstituted in mobile phase and injected into the LC-UV system. The method was successfully validated showing good linearity (from 10 ng mL−1 to 20 µg mL−1), an enrichment factor of 103 ± 2, instrumental limits of detection and quantification of 3.0 and 9.8 ng mL−1, which, according to sample treatment, correspond to 0.7 and 2.4 µg kg−1 in the sample, respectively, and a good repeatability (RSD < 14%). Finally, the proposed analytical method was applied to the determination of acrylamide in commercial cosmetic samples of different nature with good relative recovery values (85 – 112%), which shows that the matrix effect is negligible. This method could help the cosmetic industry to control the cosmetic products containing potential acrylamide-releasing ingredients.

Macro-classification of meteorites by portable energy dispersive X-ray fluorescence spectroscopy (pED-XRF), principal component analysis (PCA) and machine learning algorithms

The research on meteorites from hot and cold deserts is gaining advantages from the recent improvements of portable technologies such as X-ray fluorescence spectroscopy (XRF). The main advantages of portable instruments include the fast recognition of meteorites through their classification in macro-groups and discrimination from materials such as industrial slags, desert varnish covered rocks and iron oxides, named “meteor-wrongs”. In this study, 18 meteorite samples of different nature and origin were discriminated and preliminarily classified into characteristic macro-groups: iron meteorites, stony meteorites and meteor-wrongs, combining a portable energy dispersive XRF instrument (pED-XRF), principal component analysis (PCA) and some machine learning algorithms applied to the XRF spectra. The results showed that 100% accuracy in sample classification was obtained by applying the cubic support vector machine (CSVM), fine kernel nearest neighbor (FKNN), subspace discriminant-ensemble classifiers (SD-EC) and subspace discriminant KNN-EC (SKNN-EC) algorithms on standardized spectra.

A revised solid-state NMR method to assess the crystallinity of cellulose

The crystallinity of cellulose has a strong impact on various material properties. Over the years, many methods have become available to estimate the crystallinity. The purpose of this work was to revise existing NMR-based methods and to introduce a complementary NMR method related to the 13C T1 relaxation time. The 13C T1 differs by an order of magnitude for amorphous and crystalline polymers among them cellulose. We have utilized the signal boost of 1H–13C cross polarization and the difference in 13C T1 as a filter to calculate the degree of crystallinity. The evaluation of the method is based on the difference in peak integrals, which is fed into a simple equation. The method was applied to five cellulosic samples of different nature and compared the obtained degree of crystallinity with the degree estimated from deconvoluted X-ray scattering patterns. Furthermore, an attempt has been made to give a basic understanding on the origin of CP enhancement in order to validate various proposed NMR methods. With the recent progress of NMR equipment, the presented method can be automatized and applied to a series of samples using a sample changer.

Rapid Identification and Determination of N-Nitrosamines in Food Products by Ultra-High-Performance Liquid Chromatography–High Resolution Quadrupole-Time-of-Flight Mass Spectrometry by Exact Masses of Protonated Molecules

A method is proposed for the rapid identification and determination of seven N-nitrosamines in food products by ultra-high-performance liquid chromatography in combination with high-resolution quadrupole-time-of-flight mass spectrometry. The ranges of detectable concentrations of N-nitrosamines are from 0.001–5 to 2–100 ng/mL for liquid (water, beer) and from 2–50 to 4–100 ng/g for solid (meat, fish, mussels, malt, grain, sausage, wieners, and bockwursts) products. The limits of detection are 0.0005–2 ng/mL, 2–5 ng/g for liquid and solid products, respectively. The recovery of analytes is from 62 to 105%. The matrix effect was estimated in determining N-nitrosamines in samples of different nature. The matrix effect is negligible (≤20%) in the determination of N-nitrosamines in water and is significant for beer, meat products, grain, malt, and fish (>20%). A procedure is proposed for the rapid identification and determination of N-nitrosamines by the standard addition method and using matrix calibration. The relative standard deviation of the results of analysis does not exceed 17%. The duration of sample identification is 40 min; the determination of the detected analytes takes 1–1.5 h.

Miniaturized Matrix Solid-Phase Dispersion for the Analysis of Ultraviolet Filters and Other Cosmetic Ingredients in Personal Care Products

A method based on micro-matrix solid-phase dispersion (μ-MSPD) followed by gas-chromatography tandem mass spectrometry (GC–MS/MS) was developed to analyze UV filters in personal care products. It is the first time that MSPD is employed to extract UV filters from cosmetics samples. This technique provides efficient and low-cost extractions, and allows performing extraction and clean-up in one step, which is one of their main advantages. The amount of sample employed was only 0.1 g and the extraction procedure was performed preparing the sample-sorbent column in a glass Pasteur pipette instead of the classic plastic columns in order to avoid plastizicer contamination. Factors affecting the process such as type of sorbent, and amount and type of elution solvent were studied by a factorial design. The method was validated and extended to other families of cosmetic ingredients such as fragrance allergens, preservatives, plasticizers and synthetic musks, including a total of 78 target analytes. Recovery studies in real sample at several concentration levels were also performed. Finally, the green extraction methodology was applied to the analysis of real cosmetic samples of different nature.

Capabilities of a Two-Jet Arc Plasma for Direct Analysis of Samples of Different Nature

The capabilities of a two-jet arc plasma for solving analytical tasks that are difficult to do by other spectral methods have been shown. We have proposed procedures, both direct and after heat treatment of the sample, for the atomic emission spectroscopic analysis of brown coal and protein complexes of low weight using graphite-powder-based reference samples and simple sample preparation (dilution of the sample with spectroscopic buffer). Owing to the ability of the ATOM program to record the spectra of each base exposure, a method for detecting inclusion elements in diamond particles weighing less than 1 mg has been proposed. The advantages of this method over other spectral methods in solving specific analytical tasks are discussed. All the techniques described in the work have been performed using a new design plasmatron developed by VMK-Optoelektronika.

On-line competitive host-guest interactions in a turn-on fluorometric method to amantadine determination in human serum and pharmaceutical formulations

A competitive assay between the antiviral Amantadine and the dye Thionine for the Cucurbit[8]uril cavity was carried out in a flow injection analysis system for the indirect fluorescence detection of Amantadine. Both, Cucurbit[7]uril and Cucurbit[8]uril Thionine complexes were evaluated for the competitive assay. The use of a 12-port injection valve allows the on-line reaction in the flow system. Once optimized all the experimental variables, the methodology developed allows the detection of Amantadine at the 0.16µM level with excellent accuracy (Er ≤ 8.2%) and reproducibility (RSD ≤ 6.3%) for all the concentration range assayed. This one-step turn-on fluorescence methodology allows reaching sampling frequencies of 68 samples per hour. The selectivity of the method was evaluated against different antiviral drugs. Moreover, the performance of the methodology proposed was tested by the Amantadine determination in human serum and pharmaceutical formulations samples. The results demonstrated that the method can be applied to Amantadine determination in real samples of different nature with excellent recoveries, ranging from 83% to 98% depending on the matrix assayed.

Classification of Human Milks Based on Their Trans 18:1 Fatty Acid Profile and Effect of Maternal Diet.

The diet of breastfeeding women influences the trans fatty acid (TFA) composition of the milk excreted. However, the effects associated to TFA are isomer-dependent and diverse TFA profiles may have different nutritional implications. The aim of this research was to evaluate whether certain TFA patterns in human milk fat can be used as indicators of TFA intake from different sources. Milk fat from 60 women were examined and classified based on their TFA profile and conjugated linoleic acid (CLA) contents by principal component analysis (PCA). The PCA of the data allowed the classification of the women into 3 groups depending on milk TFA content and profile. From the 60 subjects, 19 presented a TFA profile characteristic of ruminant products intake, 10 a typical TFA profile of industrial trans fats consumption and 31 a negligible trans content. Superimposed on this, 21 women presented high amounts of docosahexaenoic acid (22:6 n-3) which was related to fish intake. The present research overcome problems associated to heterogeneous groups in nutritional experiments by a statistical classification of lactating subjects based on the TFA composition of their milk. This classification could be extrapolated to other nutritional studies dealing with TFA analysis and samples of different nature as biological samples or foodstuffs.

Determination of N-nitrosodiethanolamine in cosmetic products by reversed-phase dispersive liquid-liquid microextraction followed by liquid chromatography

A new analytical method for the determination of N-nitrosodiethanolamine (NDELA), a very harmful compound not allowed in cosmetic products, is presented. The method is based on a new approach of dispersive liquid–liquid microextraction (DLLME) useful for extraction of highly polar compounds, called reversed-phase DLLME (RP-DLLME), followed by liquid chromatography–ultraviolet/visible (LC-UV/Vis) determination. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the optimized conditions, a mixture of 750µL of acetone (disperser solvent) and 125µL of water (extraction solvent) was rapidly injected into 5mL of toluene sample solution. The extracts were injected into the LC-UV/Vis system using ammonium acetate 0.02M as mobile phase. After chromatographic separation, the eluate passed throughout a photolysis unit in order to convert NDELA to nitrite, and then it was merged with a flow stream of Griess Reagent and passed throughout a post-column reactor at 50°C to derivatize nitrite into an azo-dye, which was finally measured spectrophotometrically at 540nm. The method was successfully validated showing good linearity, an enrichment factor of 31.5±0.9, limits of detection and quantification of 1.1 and 3.6ngmL−1, respectively, and a good repeatability (RSD <8%). Finally, the proposed analytical method was applied to the determination of NDELA in commercial cosmetic samples of different nature, specifically three lipophilic creams and a hydrophilic shower gel, with good relative recovery values (87 – 117%) thus showing that matrix effects are negligible. These results were compared with those obtained by applying the ISO 10130 official method, which uses the same detection approach. It was concluded that a great improvement in the sensitivity was achieved, whereas the use of organochlorine solvents is avoided and therefore it can be considered as a greener approach.

Assessment of the Capabilities of Using a Two-Jet Arc Plasma for Direct Analysis of the Samples of Different Nature

An expediency of application of two-jet arc plasma to analytical problems, which are not easily solved by other spectral, is shown. Atomic emission techniques for analysis of brown coal and protein complex compounds of small weight, both direct and after thermal treatment of the sample, are suggested using reference samples based on graphite powder and simple sample preparation procedure of dilution of the sample by a spectroscopic buffer. Owing to “ATOM” software which provides spectrum registration of each basic exposure, a procedure of qualitative determination of the element inclusions in diamond particles (weight less than 1 mg) is developed. Advantages of this method compared to other spectral methods used for solving specific analytical tasks are discussed. All the techniques described here are performed using the new plasmatron developed at the “VMK-Optoelektronika” Company.

X-ray fluorescent analysis using synchrotron radiation: Subjects of research

The brief review has been presented about the application of X-ray fluorescent analysis using synchrotron radiation (storage ring VEPP-3, BINP SB RAS) for determination of elemental composition of the samples of different nature–biological and geological samples, objects of environment, archeological objects, and new materials. The feature of the presented research is the employment of the unique properties of synchrotron radiation, which allow analyzing samples of small mass (of the order of several milligrams), and also scanning core of bottom sediments with high resolution (less than 1 mm) that is not practical to realize by traditional analysis methods.

A set of analytical methods for the estimation of elemental and grain-size composition of volcanic ash

A combined approach to the analysis of volcanic ash (VA) was proposed. Ash particles were separated by size using a combination of vibration sieving on sieves (140, 70, 40 μm) and field-flow fractionation in a rotating coiled column (for separation of nano- and submicron particles). Initial samples and obtained fractions were characterized using scanning electron microscopy and static light scattering. Their elemental composition was determined using ICP-MS and ICP-AES methods. The radionuclide composition of the VA was studied by the low-background gamma spectrometry. The studies were carried out by the example of ashes from Puyehue volcano, the Puyehue Cordon Caulle volcanic group, Andes (Santiago, eruption on June, 2011), which were taken immediately after eruption and after first rain. It was shown that up to 15% of major elements (such as P, Ca, and К) and trace elements (such as Be, Hg, Tl, As, Sb, and Bi) could be extracted from the ash by rain and migrate into environment. It was also found that the content of radionuclides (U235, Th234, Pb214, Bi214, Be7) after rain decreases by 30–40%. Of special interest are ash nanoparticles (up to 200 nm), in which the contents of Cu, Pb, Tl, Bi, Sn, As, and Sb are over an order of magnitude higher than the bulk contents of these elements in the ash. This regularity was found in samples taken both prior to and after rain. The proposed methodology of fractionation, study, and analysis of ash particles may be applied for a wide range of soil, ash, and dust samples of different nature.