Method For Routine Analysis Research Articles

Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally.

Arsenic (As) accumulation in rice is of global concern for human health and international trade. Rice is typically reported to contain inorganic As (iAs) and dimethylated arsenate (DMA), with current food guidelines limiting toxic iAs but not less-toxic DMA. Here, we show that the highly toxic dimethylated monothioarsenate (DMMTA) is also found in rice worldwide and has been unknowingly determined as less-toxic DMA by previous routine analytical methods. Using enzymatic extraction followed by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) analysis with a C18 column, DMMTA was detected in rice grains (n = 103) from a field survey from China and in polished rice grains (n = 140) from a global market-basket survey. Concentration ranged from <0.20 to 34.8 μg/kg (median 10.3 μg/kg), accounting for 0 to 21% of total As. A strong linear correlation was observed in all rice samples between DMA and DMMTA (being 30 ± 8% of DMA) concentrations. This robust relationship allows an estimation of DMMTA in rice grains from the DMA data reported in previous market-basket surveys, showing a general global geographical pattern with DMMTA concentration increasing from the equator toward high-latitude regions. Based on the global occurrence and potential high toxicity, DMMTA in rice should be considered in health risk assessments and for setting food regulations.

Hydrocarbon Macrocycle Conformer Ensembles and 13C‐NMR Spectra

AbstractNMR as a routine analytical method provides important three‐dimensional structure information of compounds in solution. Here we apply the recently released CRENSO computational workflow for the automated generation of conformer ensembles to the quantum mechanical calculation of 13C‐NMR spectra of a series of flexible cycloalkanes up to C20H40. We evaluate the computed chemical shifts in comparison with corresponding experimental data in chloroform. It is shown that accurate and properly averaged theoretical NMR data can be obtained in about a day of computation time on a standard workstation computer. The excellent agreement between theory and experiment enables one to deduce preferred conformations of large, non‐rigid macrocycles under ambient conditions from our automated procedure.

Hydrocarbon Macrocycle Conformer Ensembles and 13 C-NMR Spectra.

NMR as a routine analytical method provides important three‐dimensional structure information of compounds in solution. Here we apply the recently released CRENSO computational workflow for the automated generation of conformer ensembles to the quantum mechanical calculation of 13C‐NMR spectra of a series of flexible cycloalkanes up to C20H40. We evaluate the computed chemical shifts in comparison with corresponding experimental data in chloroform. It is shown that accurate and properly averaged theoretical NMR data can be obtained in about a day of computation time on a standard workstation computer. The excellent agreement between theory and experiment enables one to deduce preferred conformations of large, non‐rigid macrocycles under ambient conditions from our automated procedure.

C-CorA: A Cluster-Based Method for Correlation Analysis of RNA-Seq Data

Correlation analysis is a routine method of biological data analysis. In the process of RNA-Seq analysis, differentially expressed genes could be identified by calculating the correlation coefficients in the comparison of gene expression vs. phenotype or gene expression vs. gene expression. However, due to the complicated genetic backgrounds of perennial fruit, the correlation coefficients between phenotypes and genes are usually not high in fruit quality studies. In this study, a cluster-based correlation analysis method (C-CorA) is presented for fruit RNA-Seq analysis. C-CorA is composed of two main parts: the clustering analysis and the correlation analysis. The algorithm is described and then integrated into the MATLAB code and the C# WPF project. The C-CorA method was applied to RNA-Seq datasets of loquat (Eriobotrya japonica) fruit stored or ripened under different conditions. Low temperature conditioning or heat treatment of loquat fruit can alleviate the extent of lignification that occurs because of postharvest storage under low temperatures (0 °C). The C-CorA method generated correlation coefficients and identified many candidate genes correlated with lignification, including EjCAD3 and EjCAD4 and transcription factors such as MYB (UN00328). C-CorA is an effective new method for the correlation analysis of various types of data with different dimensions and can be applied to RNA-Seq data for candidate gene detection in fruit quality studies.

Quantification and Stability Indicating Method Development and Validation of Vismodegib in Bulk and Pharmaceutical Dosage Form by Ultra Performance Liquid Chromatography

Background: Vismodegib (VMD) is a drug of choice for the treatment of basal-cell carcinoma. Present studies carried out to estimate VMD by RP-UPLC technique and to develop a simple, précised, accurate method for routine analysis.&#x0D; Methods: For this purpose Chromatographic conditions used were stationary phase STD BEH C18 column (100 mm x 2.1 mm, 1.8m), a mixture of Methanol:KH2PO4 taken in the ratio 50:50%v/v as a mobile phase with a pH 7.4 and flow rate was maintained at 0.3ml/min, detection wave length was Acquity TUV 254nm, column temperature was set to 30oC and diluent was mobile phase, Conditions were finalized as optimized method.&#x0D; Results: System suitability parameters were studied by injecting the standard six times. Linearity study was carried out between 25% to150% (37.5-225µg/ml) levels, R2 value was found to be as 0.9992. Precision was found to be 0.6 for repeatability and 0.4 for intermediate precision. LOD and LOQ are 0.33 µg/ml and 0.99 µg/ml respectively and results were well under the acceptance criteria.&#x0D; Conclusion: By using above method assay of marketed formulation was carried out and was found 100.12%. Degradation studies of VMD were done, in all conditions purity threshold was more than purity angle and within the acceptable range. The developed method was simple and can be used for routine analysis.

Optical fiber mercury biosensor based on immobilized urease and bromothymol blue onto the alginate-chitosan membrane in the flow-system

An optical fiber biosensor has been developed for the detection of mercury ion based on inhibition of urease immobilized onto alginate–chitosan membrane, coupled with bromothymol blue (BTB) in the flow system. To get a good performance of the biosensor toward Hg(II) ion detection, the experimental parameters of the biosensor were optimized. Here, the maximum wavelength was detected at 580 nm, with the optimum response at pH of 6. The calibration curve had a dynamic working range at 10 to 500 μg/L of Hg(II) ion with a detection limit of 12.1 μg/L biosensor has been performed by the addition of 1 mM ethylenediaminetetraacetic acid (EDTA) solution, in which five-time cycles have been achieved with the inhibition decrease to 9.94% from the original biosensor response. Applying the biosensor to the real samples showed conformity of results with the reference method, cold vapor atomic absorption spectrometry (CV-AAS). Therefore, this biosensor can be used as a method for routine analysis in the determination of Hg(II) concentration in an aqueous sample.

A new LC\u2013MS/MS method for multiple residues/contaminants in bovine meat

A multi-class and multi-residue/contaminant method for the determination of veterinary drug and pesticide residues and mycotoxins in bovine meat has been developed and validated. The veterinary drug residues/contaminants included antimicrobials, anabolic hormones, lactones, β-agonists, mycotoxins, and pesticides. Isotopic labeled internal standards were included to compensate residual matrix effects. The calibrators used in the method demonstrated linearity with the R2 > 0.98. The decision limit (CCα) values were in the range from 0.067 to 2103.84 μg/kg, while the range for detection capability (CCβ) was from 0.083 to 2482.13 μg/kg. The limit of detection (LOD) and limit of quantification (LOQ) were in the range from 0.059 to 291.36 μg/kg, and 0.081 to 328.13 μg/kg, respectively. The recovery of analytes ranged from 61.28% to 116.20%. The intra-day coefficient of variation (CV) was from 0.97 to 25.93% and the inter-day CV was 2.30–34.04%. The method has been used for the determination of 49 residues/contaminants in bovine meat. Application of the method in routine analysis in bovine samples, revealed in limited samples the presences of enrofloxacin, oxytetracycline and sulfadiazine at the concentration of 35.22 µg/kg, 27.35 µg/kg, and 36.20 µg/kg, respectively.

Problem and Solution of UV–Vis Time-Based Measurements of a Chemical System Involving Gas Product: Application to the Bray–Liebhafsky Oscillatory Reaction

Ultraviolet (UV)–visible (Vis) spectroscopy is widely used in all modern laboratories as a routine method of analysis. The monitoring of chemical reactions in an aqueous solution involving a gas pr...

Identification of Mammalian and Poultry Species in Food and Pet Food Samples Using 16S rDNA Metabarcoding

The substitution of more appreciated animal species by animal species of lower commercial value is a common type of meat product adulteration. DNA metabarcoding, the combination of DNA barcoding with next-generation sequencing (NGS), plays an increasing role in food authentication. In the present study, we investigated the applicability of a DNA metabarcoding method for routine analysis of mammalian and poultry species in food and pet food products. We analyzed a total of 104 samples (25 reference samples, 56 food products and 23 pet food products) by DNA metabarcoding and by using a commercial DNA array and/or by real-time PCR. The qualitative and quantitative results obtained by the DNA metabarcoding method were in line with those obtained by PCR. Results from the independent analysis of a subset of seven reference samples in two laboratories demonstrate the robustness and reproducibility of the DNA metabarcoding method. DNA metabarcoding is particularly suitable for detecting unexpected species ignored by targeted methods such as real-time PCR and can also be an attractive alternative with respect to the expenses as indicated by current data from the cost accounting of the AGES laboratory. Our results for the commercial samples show that in addition to food products, DNA metabarcoding is particularly applicable to pet food products, which frequently contain multiple animal species and are also highly prone to adulteration as indicated by the high portion of analyzed pet food products containing undeclared species.

Validation of the Developed Zero-Order Infrared Spectrophotometry Method for Qualitative and Quantitative Analyses of Tranexamic Acid in Marketed Tablets.

(1) Background: The functional groups present in tranexamic acid allow direct infrared detection analysis. This study aimed to develop, apply, and validate an infrared spectrophotometry method used for qualitative and quantitative analyses of tranexamic acid in marketed tablets. (2) Methods: This was a descriptive observational study that consisted of several stages: determining the specific wavenumber for analysis, obtaining a simple linear regression equation, analyzing tranexamic acid both qualitatively and quantitatively, and validating the developed method for routine analysis. (3) Results: The peak analysis obtained a range of baseline wavenumbers from 1679.17 to 1295.25 cm−1. The regression equation obtained was Y = 310.8527 × X + 0.9718, and the coefficient of determination (R2) obtained was 0.9994. The tranexamic acids in marketed tablets overall have a similarity index value of more than 0.90 and overall have levels ranging between 97.0% and 103.0%. The infrared spectrophotometry method that was successfully developed, applied, and validated for qualitative and quantitative analyses of tranexamic acid in marketed tablets meets the requirements both qualitatively and quantitatively of the tablet monograph. (4) Conclusions: The infrared spectrophotometry method has been validated and meets the requirements for accuracy, precision, detection limit, quantitation limit, linearity, range, and specificity.

The Ability of Near Infrared (NIR) Spectroscopy to Predict Functional Properties in Foods: Challenges and Opportunities.

Near infrared (NIR) spectroscopy is considered one of the main routine analytical methods used by the food industry. This technique is utilised to determine proximate chemical compositions (e.g., protein, dry matter, fat and fibre) of a wide range of food ingredients and products. Novel algorithms and new instrumentation are allowing the development of new applications of NIR spectroscopy in the field of food science and technology. Specifically, several studies have reported the use of NIR spectroscopy to evaluate or measure functional properties in both food ingredients and products in addition to their chemical composition. This mini-review highlights and discussed the applications, challenges and opportunities that NIR spectroscopy offers to target the quantification and measurement of food functionality in dairy and cereals.

Unsymmetrical Coumarin based dimeric liquid crystals: Synthesis, Characterization, Mesomorphic investigation, Photoluminescence and Thermal conductivity

ABSTRACT In this paper a synthesis, liquid crystal behaviours, photoluminescence and thermal conductivity have been described for new sets of unsymmetrical dimeric molecules with coumarin unit at one end connected to chalcones alky substitution by diether. Chemical proposed structure was confirmed by routine analytical methods using FT-IR, 1D NMR and 2D NMR spectroscopy and CHN elemental analysistechniques. The compounds were investigated for liquid crystalline properties using differential scanning calorimetry and polarising optical microscopy with heating assembly. Most of the compounds are showing nematic mesophases with moderate transition ranges. Photoluminescence of compounds was examined and the results indicated that the emission in the blue region reveals that material has blue light emission properties. Moreover, thermal conductivity of the prepared compounds was measured, result indicated that slight change in the structure increased the thermal conductivity.

A fast, low-cost and eco-friendly method for routine determination of Bisphenol-A in landfill leachate employing vortex assisted liquid-liquid extraction

Landfills are sites designed to receive and final disposal of a broad variety of urban solid wastes (USW). The decomposition and biodegradation processes generate a leachate of high complexity and toxicity, containing persistent and recalcitrant contaminants that are not usually monitored. Bisphenol-A (BPA) is a synthetic compound applied mostly on the production of polycarbonate plastics, epoxy resins, and is an endocrine disruptor. The presence of BPA in USW urges the development of feasible analytical methods to support the effluent treatment plants and reduce the risks of contamination. The main goal of this work was to develop an efficient, eco-friendly, fast and simple method for routine analysis of BPA in the leachate from landfill. A vortex assisted liquid-liquid extraction (VALLME) using 1-octanol as solvent was performed. BPA recoveries at spiking levels of 2.5, 6.5 and 12.5 µg L-1 were between 60 to 104% with relative standard deviation (RSD) lower than 26%. The linearity of the method was evaluated and the correlation coefficient was (r) 0.9985. The limit of quantification (LOQ) was 2.5 µg L-1 with a pre-concentration factor of 20. The method has advantages such as low consumption of extraction solvent (150 µL), low cost, easy and fast determination.

Detection of adulterations in a valuable Brazilian honey by using spectrofluorimetry and multiway classification

Spectrofluorimetry combined with multiway chemometric tools were applied to discriminate pure Aroeira honey samples from samples adulterated with corn syrup, sugar cane molasses and polyfloral honey. Excitation emission spectra were acquired for 232 honey samples by recording excitation from 250 to 500 nm and emission from 270 to 640 nm. Parallel factor analysis (PARAFAC), partial least squares discriminant analysis (PLS-DA), unfolded PLS-DA (UPLS-DA) and multilinear PLS-DA (NPLS-DA) methods were used to decompose the spectral data and build classification models. PLS-DA models presented poor classification rates, demonstrating the limitation of the traditional two-way methods for this dataset, and leading to the development of three-way classification models. Overall, UPLS-DA provided the best classification results with misclassification rates of 4% and 8% for the training and test sets, respectively. These results showed the potential of the proposed method for routine laboratory analysis as a simple, reliable, and affordable tool.

Method development for optimizing analysis of ignitable liquid residues using flow-modulated comprehensive two-dimensional gas chromatography

The abundance and composition of matrix compounds in fire debris samples undergoing ignitable liquid residue analysis frequently leads to inconclusive results, which can be diminished by applying comprehensive two-dimensional gas chromatography (GC × GC). Method development must be undertaken to fully utilize the potential of GC × GC by maximizing separation space and resolution.. The three main areas to consider for method development are column selection, modulator settings and parameter optimization. Seven column combinations with different stationary phase chemistry, column dimensions and orthogonality were assessed for suitability based on target compound selectivity, retention, resolution, and peak shapes, as well as overall peak capacity and area use. Using Box-Behnken design of experimentation (DoE), the effect of modulator settings such as flow ratio and loop fill capacity were evaluated using carbon loading potential, dilution effect, as well as target peak amplitude and skewing effect. The run parameters explored for parameter optimization were oven programming, inlet pressure (column flow rate), and modulation period. Comparing DoE approaches, Box-Behnken and Doehlert designs assessed sensitivity, selectivity, peak capacity, and wraparound; alongside target peak retention, resolution, and shape evaluation. Certified reference standards and simulated wildfire debris were used for method development and verification, and wildfire debris case samples scrutinized for method validation. The final method employed a low polarity column (5% diphenyl) coupled to a semi-polar column (50% diphenyl) and resulted in an average Separation Number (SN) exceeding 1 in both dimensions after optimization. Separation Numbers of 18.16 for first and 1.46 for second dimension without wraparound for compounds with at least four aromatic rings signified successful separation of all target compounds from varied matrix compositions and allowed for easy visual comparison of extracted ion profiles. Mass spectrometry (MS) was required during validation to differentiate ions where no baseline separation between target compounds and extraneous matrix compounds was possible. The resulting method was evaluated against ASTM E1618 and found to be an ideal routine analysis method providing great resolution of target compounds from interferences and excellent potential for ILR classification within a complex sample matrix.

GC-MS – Still standing for clinical and forensic analysis: validation of a multidrug method to detect and quantify illicit drugs

ABSTRACT An SPE-GC-MS analytical method using whole blood samples has been developed and validated to detect and quantify nineteen compounds belonging to the Drugs of Abuse (DA) groups of cocaine and metabolites, opiates and new psychoactive substances (NPS). The method detailed here is necessary because the recreational consumption of these DA has increased considerably in recent years and poly-drug-consumption is now very common. The method developed was both specific and selective. Three different working ranges have been defined due to the differences between therapeutic, toxic and lethal concentrations of DA. Linearity was confirmed for the defined working ranges of all DA, except pseudoephedrine, ephedrine, norephedrine, and TFMPP. Since the remaining nineteen substances showed heteroscedasticity, six ponderation factors were studied to find the best fit for each compound. Limits of Detection and Lower Limits of Quantification have been studied and defined. No carryover was noted, with acceptable extraction recoveries. The achievement of all validation criteria according to international guidelines allows the application of the proposed method in routine forensic analysis. Using this method can also significantly reduce response times and GC-MS analysis costs.

Development and Validation of a Stability-Indicating Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) Method for Identification, Assay, and Estimation of Related Substances of Ivermectin Drug Substance.

Ivermectin is a potent semi-synthetic antiparasitic drug used in veterinary medicine. It is widely used for the treatment of parasites. This study aimed to develop a stability-indicating reversed-phase HPLC (RP-HPLC) method for assay and identification of ivermectin including identification and estimation of its related substances in bulk drug substance batches of ivermectin. Ivermectin and its related substances were separated on an Ascentis Express C18 column (100 mm × 4.6 mm id, 2.7 µm particle size) maintained at 45°C (column temperature) on an HPLC system with gradient elution. The mobile phase was composed of water - acetonitrile (ACN; 50 + 50, v/v) as mobile phase A, and isopropanol - ACN (15 + 85, v/v) as mobile phase B. Analytes were detected with a detection wavelength of 252 nm and quantitated against an external reference standard of ivermectin with a quantitation limit of 0.1% of the target (analytical) concentration. The HPLC method was able to separate all analytes of interest by gradient elution within 25 min. The method was validated according to the guidelines described in the International Conference on Harmonization guideline Q2(R1). The HPLC method for assay of ivermectin and estimation of its related substances was successfully developed, validated, and demonstrated to be accurate, robust, specific, and stability indicating. The performance of the HPLC method is significantly faster and possesses a higher degree of selectivity. Implementation of this method for routine analysis in QC laboratories would save significant time, resources and solvents.

FORCED DEGRADATION STUDIES OF TIZANIDINE HYDROCHLORIDE AND DEVELOPMENT OF VALIDATED STABILITY-INDICATING RP-HPLC METHOD

Simple and precise stability indicating RP-HPLC method for the quantitative determination of tizanidinehydrochloride (TZN) in pharmaceutical dosage form was developed and validated. The separation was achieved using Atlantis C18 column (250 x 4.6 mm, 5µm) at 25 °C using a mobile phase containing 20mM KH2 PO4 (pH 3.5):methanol in the ratio of 30:70 V/V at 0.8 mL/min flow rate and 315nm detection wavelength. The retention time for TZN was 3.7 min and showed linearity in the 5-40µg/mL range with R2 &gt;0.99. The drug was subjected to acid/ base hydrolysis, oxidative and thermal degradation to establish stability indicating method. The method was validated as per ICHQ2 (R1) guidelines. The method was accurate, precise, and specific for TZN estimation. In stress studies, the drug was found to be stable to acid/alkaline hydrolysis, oxidation, and thermal degradation conditions. Thus, the reported method can be used as a stability-indicating method for quality control and routine analysis of TZN.

Expediting Disulfiram Assays through a Systematic Analytical Quality by Design Approach

An Analytical Quality by Design (AQbD) approach is presented, aiming at the development and validation of an HPLC method for the quantification of disulfiram and copper diethyldithiocarbamate in lipid nanoparticles. Following the definition of the analytical target profile (ATP), encompassing the critical analytical attributes (CAA), a two-level risk assessment strategy (Ishikawa diagram—failure mode and effect analysis (FMEA)) was employed to identify the critical method parameters (CMPs) with an extensive impact on method performance. The behavior of the CMPs (flow rate and mobile phase composition) was further characterized by experimental design, resorting to a face-centered central composite design (FcCCD). Statistical modeling, response surface analysis, and Monte Carlo simulations led to the definition of the Method Operable Design Region (MODR), associated with a negligible risk of failing the predefined CAA specifications. The optimal method was validated according to international regulatory recommendations. Apart from guaranteeing linearity, accuracy, precision, specificity, robustness, and stability, these conditions were found to be suitable for analysis using a different HPLC column and equipment. In a nutshell, the development and optimization strategies, under the comprehensive framework of AQbD, provided an effective, simple, rapid, reliable, and flexible method for routine analysis of the compounds in research or industrial environments.

Determination of ethanol in foods and beverages by magnetic stirring-assisted aqueous extraction coupled with GC-FID: A validated method for halal verification

An in-house method, employing magnetic stirring-assisted aqueous extraction combined with gas chromatography-flame ionization detector, for determination of ethanol in different foods and beverages was validated according to the ISO/IEC 17025 standard. Validation parameters, including selectivity, method limits of detection (approx. 0.006 mg/g) and quantification (approx. 0.02 mg/g), linearity (R2 of >0.999), trueness (relative biases of <3%), accuracy (recoveries of 96–105%), and precision (relative standard deviations of <5%), were satisfactory. The proposed method was as accurate and precise as and more sensitive than the AOAC method 2016.12, with estimated relative expanded uncertainties of around 8% for all samples. The validated method was successfully applied for determination of ethanol in 108 commercially processed foods and beverages, and it could be used for halal verification. Accordingly, this study provided a reliable method for routine quantitative analysis of ethanol in processed foods and beverages to ensure their halal integrity prior to halal certification.