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The quality of pesticide formulations has an impact on the crop safety, environment and human health. Therefore, the development of new analytical methods for the determination of active substances in pesticide formulations in order to control their quality, as well as, their residues in food samples in order to ensure food safety, is always welcome. A new, simple, precise and accurate normal-phase high-performance liquid chromatography (NP-HPLC) method for determination of an active ingredient malathion in the commercial emulsifiable concentrate pesticide product has been developed and validated. The analysis was carried out on a LiChrosorb CN (250 x 4 mm, 5 μm) analytical column using isocratic elution with mobile phase consisted of n-hexane and dichloromethane (80/20, v/v), flow rate of 1 mL/min, constant column temperature at 25 °C and ultraviolet diode-array detection at 220 nm. The obtained values for multiple correlation coefficients (R 2 ≥ 0.9990), relative standard deviation of retention times, peak areas and heights (RSD ≤ 1.14%), recoveries ranged from 98.97 to 101.62%, revealed that the developed method has a satisfactory linearity, precision and accuracy. Also, the developed method was successfully applied for determination of malathion residues in apple juice samples, after preliminary sample preparation using solid-phase extraction. Specificity, selectivity, linearity, matrix effect, precision and accuracy were tested in order to validation of this method. The obtained results were in acceptable ranges and indicated that the developed method is suitable for routine determination of malathion in the pesticide formulation, as well as for determination of malathion residues in apple juice samples. The run time of HPLC analysis was about 6 min.

We calculate the specific heat and susceptibility of rare earth magnetic superconductors in the context of the Ginzburg–Landau theory. The specific heat and susceptibility are calculated at both the coexistence phase of antiferromagnetism and superconductivity and normal phase. Theoretical results are compared with experimental results which agree excellently well.

We investigated the amount of polyphenols present in three types of stone fruits (peaches, plums, and prunes) that were produced in Japan during 2018 and 2019 using reversed-phase high-performance ...

The chromatographic characteristics were investigated for eight aromatic derivatives of 3-chloro-1,4-naphthoquinone under conditions of normal-phase thin-layer chromatography for benzene-based binary mobile phase and such polar solvents as chloroform, acetone, acetonitrile, methanol and propan-2-ol. The slope of linear retention dependencies for the investigated compounds on the concentration of the polar component in the mobile phase satisfactorily correlates with the area occupied by the adsorbed analyte molecule in the stationary phase. The intercept in the Soczewinski equation depends on the polar component of the mobile phase.

The chromatographic analysis of a number of β-blockers on different thin-layer chromatography (TLC) systems was carried out. The analysis was done on three different systems, namely normal phase, p...

An analytical method was developed for the quantitation of the mineral oil aromatic hydrocarbons in cosmetic raw materials separating those of one or two aromatic rings from those of three and more aromatic rings. Normal phase high performance liquid chromatography was used with donor-acceptor complex chromatography. The composition of both fractions and the quantities of respective compounds were determined by comprehensive two dimensional gas chromatography with time of flight mass spectrometry and by liquid chromatography coupled to gas chromatography with flame ionization detection.

This work reports about a screening of four adsorbents with different polarity employed for the separation of the main phytocannabinoids contained in Cannabis sativa L., under normal phase liquid chromatography (NPLC). The effect of polarity and type of interaction mechanisms of the adsorbents (namely Si-, CN-, Diol-, and NH2-based SPs) on retention has been investigated under a variety of conditions either by using different combinations of apolar solvents (heptane or hexane) and alcohols (ethanol or isopropanol). The columns have also been employed for the separation of a real cannabis sample.

The fractality effect of the normal phase clusters' boundaries of a high-temperature superconductor YBa2Cu3O7−x (YBCO) on the magnetic flux creep is investigated. Experimental current-voltage and magnetoresistive characteristics of YBCO at the boiling point of nitrogen are obtained. Based on the model of intergranular clusters with fractal boundaries, an approximation of the experimental data is obtained after geometric-probability analysis of the photomicrographs of the samples. A model of the magnetoresistive state caused by flux creep is proposed for various transport currents, and experimental and empirical dependences of the fractal dimension of the normal YBCO phase cluster boundaries on the constant magnetic field are found. The magnetic field intensity is determined for a given fractal dimension, at which the vortex penetration into the granules begins. It is shown that the state of the samples corresponds to the metastable phase of the vortex glass. The connectivity index of the stall paths of the vortex bundles at the percolation threshold is calculated.

The increased use and applicability of Cannabis and Cannabis-derived products has skyrocketed over the last 5 years. With more and more governing bodies moving toward medical and recreational legalization, the need for robust and reliable analytical testing methods is also growing. While many stationary phases and methods have been developed for this sort of analysis, chiral stationary phases (CSPs) are unique in this area; not only can they serve their traditional chiral separation role, but they can also be used to perform achiral separations. Given that mixtures of cannabinoids routinely contain enantiomers, diastereomers, and structural isomers, this offers an advantage over the strictly achiral-only analyses. This work presents the separation of a 10-cannabinoid mixture on several polysaccharide-based sub-2 µm CSPs with both normal-phase and reversed-phase ultra-high-performance liquid chromatography (UHPLC) conditions. Along with the separation of the mixture, appropriate single-peak identification was performed to determine the elution order and reported where applicable.

The rapid, highly-sensitive and ecologically greener reversed-phase (RP)/normal-phase (NP) high-performance thin-layer chromatography (HPTLC) densitometric technique has been developed and validated for the determination of trans-resveratrol (TRV). The reversed-phase HPTLC-based analysis of TRV was performed using ethanol–water (65:35, v v−1) combination as the greener mobile phase, while, the normal-phase HPTLC-based estimation of TRV was performed using chloroform–methanol (85:15, v v−1) combination as the routine mobile phase. The TRV detection was carried out at 302 nm for RP/NP densitometric assay. The linearity was recorded as 10–1200 and 30–400 ng band−1 for RP and NP HPTLC techniques, respectively. The RP densitometric assay was observed as highly-sensitive, accurate, precise and robust for TRV detection in comparison with the NP densitometric assay. The contents of TRV in commercial formulation were recorded as 101.21% utilizing the RP densitometric assay, while, the contents of TRV in commercial formulation were found to be 91.64% utilizing the NP densitometric assay. The greener profile of RP/NP technique was obtained using the analytical GREEnness (AGREE) approach. The AGREE scales for RP and NP densitometric assays were estimated 0.75 and 0.48, respectively. The recorded AGREE scale for the RP densitometric assay indicated that this technique was highly green/the ecologically greener compared to the NP densitometric assay. After successful optimization of analytical conditions, validation parameters, AGREE scale and chromatography performance, the RP densitometric assay with univariate calibration was found to be better than the NP densitometric assay for the analysis of TRV.

Aims: A chiral HPLC–MS/MS method for quantitation of an active metabolite (M2) of abrocitinib was validated in human plasma. Methods: Protein precipitation extraction and normal phase LC with baseline separation of five analytes (abrocitinib; isomeric metabolites M1, M2, M3 and M4) were achieved followed by mass spectrometric quantitation of M2 using positive-mode APCI. Results: With a 5–5000 ng/ml assay range using 100 μl K2EDTA aliquot, the assay provided short (17-min) runtime and robust separation up to approximately 330 injections on one column. Interday and intraday accuracy ranged from ‐6.80% to 13.4%; between-day and within-day precision was ≤10.4%. Conclusion: The method was used in multiple clinical studies, with excellent run passing rate and incurred sample reproducibility.

Understanding the relation between chemical characteristics and properties of synthetic polymers is one of the challenges faced by analytical chemists in industry. This is a complex task, as polymers are not synthesized as single molecule, but are populations of chemically similar compounds with distributions over several properties. The latter include, for example, molecular weight, nature of end-groups (functionality), and chemical composition. In this paper, comprehensive two-dimensional liquid chromatography was used to determine the combined functionality-type and molecular-weight distributions of hydroxy-functionalized propoxylates. Propoxylates derived from different initiators (one up to eight terminal hydroxyl groups) were separated in the first dimension using a gradient normal-phase LC separation (NPLC). In the second dimension ultra-high pressure size-exclusion chromatography separation (UHPSEC), further speciating distributions based on molecular size. The developed NPLC x SEC method with evaporative light-scattering detection can be used for the fast screening (< 30 min) of mutually dependent functionality-type and molecular weight distributions of unknown propoxylates. (C) 2021 The Authors. Published by Elsevier B.V.

The greenness evaluation of literature analytical methods for pterostilbene (PT) analysis was not performed. Accordingly, the rapid, sensitive, and green/sustainable reversed-phase high-performance thin-layer chromatography (RP-HPTLC) method was developed and compared to the normal-phase (NP)-HPTLC (NP-HPTLC) for the estimation of PT with a classical univariate calibration. The RP quantification of PT was performed using green solvent systems, however, the NP analysis of PT was performed using routine solvent systems. The PT was detected at 302 nm for both of the methods. The greenness scores for the current analytical assays were evaluated by the analytical GREEnness (AGREE) metric approach. The classical univariate calibration for RP and NP methods indicated the linearity range as 10–1600 and 30–400 ng band−1, respectively. The RP method was more reliable for PT analysis compared to the NP method. The PT contents in commercial capsule dosage form were found to be 100.84% using the RP method, however, the PT contents in commercial capsule dosage form were determined as 92.59% using the NP method. The AGREE scores for RP and NP methods were 0.78 and 0.46, respectively. The sustainable RP-HPTLC assay was able to detect PT in the presence of its degradation products, and hence it can be considered as a selective and stability-indicating method. Accordingly, the RP-HPTLC method with univariate calibration has been considered as a superior method over the NP-HPTLC method for PT analysis.

We in this paper investigate the spin squeezing in relation with the phase transition from the normal to superradiant phases for two atoms in an optical cavity. The squeezing vanishes in the normal phase and jumps sharply to the maximum bound above the critical point of phase transition. In the high atom-field coupling regime, the squeezing vanishes again when the atom-field coupling reaches a threshold value. The squeezing alternates between two spin components in the intermediate region of atom-field coupling. An interesting observation is that the two spin components are squeezed alternately with the variation of phase angle of the cavity field. The squeezing factor indeed can be used to probe the phase transition and coherent-field properties as well.

Phytochemical investigation of the aerial parts of Perovskia abrotanoides (Lamiaceae) by normal phase column chromatography resulted in the isolation of perovskanol (1), a novel sesquiterpenoid possessing a 5/7/5 fused carbon ring skeleton. The structure of 1 was established by comprehensive spectroscopic data analysis including 1 D and 2 D NMR and HRESIMS. The antiprotozoal activity of compound 1 was evaluated against Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani, Plasmodium falciparum and no promising activities were shown against all parasite tested.

Evaluating lumefantrine enantioselectivity and properly quantifying its enantiomers is essential for a deeper understanding of the impact of the enantioselectivity in the pharmacodynamic and pharmacokinetic properties of the drug. For this, a chiral chromatographic method was developed and validated for the separation of lumefantrine enantiomers. The method developed employed a Chiralpack AD-H column (150 × 4.6 mm, 5 μm), with amylose tris-3,5-dimethylphenylcarbamate stationary phase, at 25 °C, mobile phase composed of hexane and isopropanol (97:3), flow rate of 1.0 mL/min and detection at 335 nm. The method showed adequate resolution for lumefantrine enantiomers and was validated for linearity (48–72 µg/ml for each enantiomer), precision, accuracy, selectivity and robustness. The proposed method was successfully applied for determination of lumefantrine enantiomers in tablet formulations and may be useful to future researchers for chiral evaluation of lumefantrine.

A method using normal phase high performance liquid chromatography for the analysis of olefins and diolefins in cracked petroleum samples is proposed and validated in this work. A silver-impregnate...

Normal phase high-performance liquid chromatographic enantiomeric separation of chiral amines as naphthaldimine derivatives was performed on amylose...

Supercritical fluid chromatography (SFC) is known since the early 1960's and it has gone through several ups and downs during the past 50 years. The most remarkable rebirth came at the beginning of the millennium, when SFC gained its popularity in many laboratories due to the significant improvements in instrumentation resulting in high reliability and robustness. New developments in SFC column chemistries and possibility of mixing CO2 with organic solvents allowed the analysis of various compounds differing in polarities, acid-base properties, and molecular weight. Hyphenation of advanced SFC platforms with mass spectrometry (MS) provides benefits similar to liquid chromatography (LC) hyphenated with MS, i.e. sensitivity and selectivity. SFC is complementary to the most widely used reversed phase LC due to the similar polarity profile to normal phase LC. This orthogonality and different separation mechanism can effectively solve the presence of matrix effects or challenging separations. In addition, SFC can be beneficial in analysis of chiral or unstable compounds difficult to analyze in LC or GC. Current SFC-MS is mostly used as a fast and green approach in a variety of research fields including bioanalysis, omics sciences, plant, food, and environmental analyses.

This review covers literature investigating methods for enantioselective chromatography using supercritical fluids as mobile phase constituents (SFC) in the field of bioanalysis. It provides an overview on method development and screening approaches published in scientific literature 2014-2018. Chiral stationary phases are used to create a chiral environment that allows for discrimination of enantiomers. Especially polysaccharide-based stationary phases are used in methods of recent investigations. In comparison to HPLC chiral SFC separation provides more selective cavity effects of inclusion-type chiral separation phases. Modifier and additive choices as well as further operating conditions like backpressure, temperature and flow rate are summarized and critically discussed. Further on, observed sample pretreatment and possible detection techniques are presented. SFC hyphenated to mass detection was found of major relevance and is therefore further discussed. Coupling of SFC with different detectors allows for straightforward use in bioanalysis. Interfacing MS detectors is generally performed including a make-up pump. Thus, applied make-up conditions were also reviewed. While most of the chiral separations in HPLC are performed in normal phase mode, and thus, challenge MS hyphenation, SFC-MS hyphenation can be easily achieved. This allows for convenient application in chiral trace analyses, often required in bioanalysis. Even worse in enantioseparation than in achiral chromatography, method development in SFC suffers from a lack of knowledge in separation mechanisms and thus approaches are often quite unique and most often achieved by screening using a One-Factor-at-a-Time (OFAT) design. Broad screening experiments with methodical approaches still appear as method of choice for now.

Green and sustainable processes to develop and manufacture pharmaceuticals using eco-friendly and environmentally responsible means have been underway for over 25 years. These include the major analytical chemistry techniques used for pharmaceutical characterization. The pharmaceutical industry as a whole needs to responsibly transition away from traditional chromatographic methodologies that include the use of longer columns, extended run times, toxic non-polar solvents (e.g. heptanes and hexanes for normal phase liquid chromatography) and their accompanying large solvent volume consumption - toward more efficient, greener solutions. Over the last decade, high pressure liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) techniques have undergone substantial improvements to instrumentation (e.g. UHPLC and UHPSFC) and column particle technologies, all of which lead to faster and more efficient separations while reducing development and validation time for both chiral and achiral analyses. However, many of these advances have yet to be globally adopted in later stage drug development and manufacturing where chromatographic process usage requires multiple analyses for every method transfer, validation, and clinical supply campaign. In order to emphasize greener method alternatives, we introduce a new approach to definitively establish the impact of method design and instrument selection choices. Our aim is to provide awareness and guidance to the global industry with a single unified, straightforward metric that clearly shows the benefit of selecting more modernized, safer and more environmentally-friendly methods and techniques without compromising separation performance.

Normal-phase high-performance liquid chromatography (HPLC) is widely used in combination with evaporative light scattering detection (ELSD) for separating and detecting lipids in various food samples. ELSD responses of different lipids were evaluated to elucidate the possibilities and challenges associated with quantification by means of HPLC-ELSD. Not only the number and type of polar functional groups but also the chain length and degree of unsaturation of (free or esterified) fatty acids (FAs) had a significant effect on ELSD responses. Tripalmitin and trilinolein yielded notably different ELSD responses, even if their constituting free FAs produced identical responses. How FA structure impacts ELSD responses of free FAs is thus not predictive for those of triacylglycerols and presumably other lipids containing esterified FAs. Because ELSD responses of lipids depend on the identity of the (esterified) FA(s) which they contain, fully accurate lipid quantification with HPLC-ELSD is challenging and time-consuming. Nonetheless, HPLC-ELSD is a good and fast technique to semi-quantitatively compare the levels of different lipid classes between samples of comparable FA composition. In this way, lipid profiles of different flours from near-isogenic wheat lines could be compared. ispartof: Foods vol:2021 issue:10 ispartof: location:Switzerland status: published