Repeatability Precision Research Articles

Multiple heart-cutting two-dimensional liquid chromatography/charged aerosol detector assay of ginsenosides for quality evaluation of ginseng from diverse Chinese patent medicines

For quality control of Chinese patent medicines (CPMs) containing the same herbal medicine or different herbal medicines that have similar chemical composition, current ″one standard for one species″ research mode leads to poor universality of the analytical approaches unfavorable to discriminate easily confused species. Herein, we were aimed to elaborate a multiple heart-cutting two-dimensional liquid chromatography/charged aerosol detector (MHC-2DLC/CAD) approach to quantitatively assess ginseng from multiple CPMs. Targeting baseline resolution of 16 ginsenosides (noto-R1/Rg1/Re/Rf/Ra2/Rb1/Rc/Ro/Rb2/Rb3/Rd/Rh1/Rg2/Rg3/Rg3(R)/24(R)-p-F11), experiments were conducted to optimize key parameters and validate its performance. A Poroshell 120 EC-C18 column and an XBridge Shield RP18 column were separately utilized in the first-dimensional (1D) and the second-dimensional (2D) chromatography. Eight consecutive cuttings could achieve good separation of 16 ginsenosides within 85 min. The developed MHC-2DLC/CAD method showed good linearity (R2 > 0.999), repeatability (RSD < 6.73%), stability (RSD < 5.63%), inter- and intra-day precision (RSD < 5.57%), recovery (93.76–111.14%), and the limit of detection (LOD) and limit of quantification (LOQ) varied between 0.45–2.37 ng and 0.96–4.71 ng, respectively. We applied it to the content determination of 16 ginsenosides simultaneously from 28 different ginseng-containing CPMs, which unveiled the ginsenoside content difference among the tested CPMs, and gave useful information to discriminate ginseng in the preparation samples, as well. The MHC-2DLC/CAD approach exhibited advantages of high specificity, good separation ability, and relative high analysis efficiency, which also justified the feasibility of our proposed ″Monomethod Characterization of Structure Analogs″ strategy in quality evaluation of diverse CPMs that contained different ginseng.

Simultaneous determination of paracetamol and caffeine by RP-HPLC in soft gelatin capsules

A rapid and stability-indicating RP-HPLC method was developed for simultaneous estimation of paracetamol and caffeine in soft gelatin capsules form especially to get some more advantages over other methods already developed for this combination. The method was validated according to ICH guideline with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity, forced degradation and system suitability. For this, an isocratic condition of mobile phase comprising acetonitrile and phosphate buffer (pH 3.5) in a ratio of 15:85, v/v over YMC C18 column (250 × 4.6 mm, 5 μm) at a flow rate of 1 mL/minute at ambient temperature was maintained. The method showed excellent linear response with correlation coefficient (R2) values of 0.999 and 1.0 for paracetamol and caffeine respectively, which were within the limit of correlation coefficient (R2 &gt; 0.995). The percent recoveries for two drugs were found within the acceptance limit of (98.0–102.0%). % RSD values for repeatability, reproducibility and Intermediate precisions were below 2.0. Forced degradation of the drug product was carried to establishing the stability-indicating property of this method and providing useful information about the degradation pathways, degradation products, and how the quality of a drug substance and drug product changes with time under the influence of various stressing conditions.

Determination of Gingerols and Shogaols Content from Ginger (Zingiber officinale Rosc.) through Microwave-Assisted Extraction

Ginger (Zingiber officinale Rosc.) is a plant recognized for its pungent taste and aromatic qualities, primarily derived from its underground rhizome. Apart from its widespread culinary applications, ginger is valued for its potential health benefits attributed to the presence of gingerols and shogaols. For this reason, this work proposes the development of a microwave-assisted extraction (MAE) method for the extraction of gingerols and shogaols present in ginger rhizomes. The influence of the extraction temperature (50–100 °C), the solvent composition (50–100% ethanol in water), and the sample-to-solvent ratio (0.3–0.7 g sample: 20 mL) on the extraction of these bioactive compounds has been studied. To this end, a Box–Behnken experimental design (BBD) in combination with a response surface methodology (RSM) has been applied. The optimum conditions for the total extraction of gingerols and shogaols were: 87% ethanol in water, 100 °C, and 0.431 g of ginger sample in 20 mL solvent. The developed method required short extraction times (5 min) and demonstrated favorable levels of repeatability and intermediate precision (CV &lt; 5%). Finally, the MAE method was successfully used for the extraction of gingerols and shogaols from a variety of ginger samples.

Longitudinal magneto-optical Kerr effect in subwavelength thick ferromagnetic films investigated by Mueller matrix ellipsometry

Accurately characterizing the magneto-optical (MO) Kerr and optical responses of subwavelength thick ferromagnetic films is of great significance in the field of MO devices. In this paper, an in-situ characterization method based on the Mueller-matrix ellipsometry in a longitudinal MOKE configuration has been proposed, with which the longitudinal MO Kerr effects phenomenon occurring in the sub-wavelength thick ferromagnetic films can be thoroughly investigated. We establish an analytical representation of the MO Kerr responses by simplifying the transfer-matrix model using a more appropriate constraint about the film thickness. By virtue of the high repeatability precision of the measured Mueller matrix better than 0.0002, the MO Kerr response signal of the ferromagnetic films with thicknesses far from the ultra-thin limit 2π|N|∙d/λ<<1 can be reliably captured, despite the well-known weak signal amplitudes. The MO coupling constant, the Kerr ellipticities and rotations can be further determined from the measured Mueller matrix. Experimental results on the Ni and NiFe2O4 films with thicknesses less than 100 nm demonstrate the proposed characterization approach based on the Mueller matrix ellipsometry as a practical and precise technique. As the film thickness increases to larger than the ultrathin film threshold, the proposed method can provide more reasonable characterization results, and the influence of film thickness on the MO responses can be more accurately evaluated.

Development of a solid-phase dispersive extraction method for molecularly imprinted polymers and LC-MS/MS for analysis of clenbuterol residues in swine livers and kidneys.

Clenbuterol (CLB) is approved as a veterinary drug because of its tracheal smooth muscle and uterine relaxant effects. However, if improperly administered for the purpose of fattening livestock, CLB can remain in the organs, which may pose a health hazard to humans. We aimed to examine the combination of molecularly imprinted polymer (MIP) and solid-phase dispersive extraction (SPDE) as a pretreatment method for swine liver and kidney, which contain more coexisting impurities than muscle tissue, and attempted to construct an analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Swine livers and kidneys were homogenized and extracted using liquid-liquid partitioning with an ethyl acetate/n-hexane mixture (1:1), followed by SPDE using an MIP gel, and measured using LC-MS/MS. For LC-MS/MS, either an absolute calibration method or isotope dilution mass spectrometry (IDMS) was used. For method validation, a recovery test (additive concentrations: 0.05 and 0.5 ng/g) was conducted, and the data were analyzed using one-way analysis of variance (ANOVA). The recoveries (trueness), repeatability, and intermediate precision obtained using absolute calibration were similar to those obtained using IDMS. Using MIP-SPDE as a pretreatment method for CLB in swine liver and kidney samples yielded comparable results for absolute calibration and IDMS in LC-MS/MS analysis. MIP-SPDE can be used as a pretreatment method to analyze CLB in swine organs with high accuracy.

Salting-Out-Assisted Liquid-Liquid Extraction Method for the Determination of Nicotine from Oral Traditional and Innovative Tobacco Products Using UPLC-MS/MS.

In this study, we developed and validated a novel method that allows for the extraction and quantitation of nicotine from a variety of commercially available oral tobacco products including loose and pouched traditional moist smokeless tobacco products, and oral tobacco-derived nicotine (OTDN) lozenges, gums, and pouches. The method employed an extraction technique consisting of salting-out assisted liquid-liquid extraction using sodium hydroxide and acetonitrile in conjunction with ultra-high pressure liquid chromatography coupled to mass spectrometry. Accurate quantitation was obtained using nicotine methyl-d3 isotopically labeled internal standard. Chromatographic separation of nicotine and nicotine methyl-d3 internal standard was achieved using a Waters Acquity C18 column (50 mm × 2.1 mm i.d., 2.5 μm) with 10 mM ammonium acetate buffer (pH = 10) and acetonitrile as mobile phase A and B, respectively. Using a gradient elution and a flow rate of 0.4 mL/min for 5 min runtime, nicotine eluted at 1.74 min. The method was validated according to ICH guidelines for all the sample types with an accuracy for nicotine within 89-109%. Repeatability and intermediate precision were both estimated to be ≤7% relative standard deviation (% RSD). This method is applicable for a wide range of traditional moist smokeless and OTDN tobacco products.

Development and validation of capillary electrophoresis sodium dodecyl sulfate (CE-SDS) method for purity analysis of pertussis toxin, filamentous haemagglutinin and pertactin antigens

We report here the development and validation of CE-SDS method for purity analysis of Acellular Pertussis vaccine components viz. purified Pertussis toxin (PTx), purified Filamentous haemagglutinin (FHA), and Pertactinantigen (PRN). The method was found to be specific and showed excellent linearity at a concentration range of 15.62 µg/mL−1000 µg/mL for purified PTx, 31.25 µg/mL−1000 µg/mL for purified FHA, and 3.9 µg/mL−1000 µg/mL for PRN antigen. Method reported limit of quantification (LOQ) 31.25 µg/mL, 62.5 µg/mL, and 7.8 µg/mL for purified PTx, FHA, and PRN respectively. Method precision (repeatability and intermediate precision) for purity and molecular weight determination in product matrix was below 10% for all three proteins. Method comparability studies were performed with SDS-PAGE. CE-SDS demonstrated corroborating results with SDS-PAGE for the estimation of purity and molecular weight analysis. However, CE-SDS method exhibited better resolution capabilities for resolving all the sub-unit peaks of PTx and isoforms of purified FHA. CE-SDS method also demonstrated stability indicating potential and thus fits its intended purpose as an effective analytical tool for quality control of acellular pertussis-based vaccines.

Validasi Metode Penetapan Bahan Aktif Permethrin dalam Insektisida dengan High Performance Liquid Chromatography (HPLC)

Insecticides are substances or chemicals that are used to kill or eradicate insects. One of the active ingredients contained in insecticide products is permethrin. One of the tests carried out was testing the levels of the active ingredient such as permethrin in insecticides. This testing was carried out by High Performance Liquid Chromatography (HPLC). This method is a new method that will be used for routine analysis testing laboratory at Laboratory. The method that is used refers to the journal Validated High Performance Liquid Chromatography (HPLC) Method for Quantifying Permethrin in Pharmaceutical Formulations. Therefore, it is necessary to validate this method regarding elements that can cause variations in the test results and identify factors that can affect the performance of the method and determine the magnitude of the effect. Based on the test results, it can be concluded that all the validation parameters of the testing method for determining the active ingredient permethrin by high performance liquid chromatography gave the results of specificity, linearity, instrument detection limit (LDI), quantitation limit (LQ), repeatability precision, intermediate precision, accuracy, and the rigidity of the method meets the CIPAC 3807 requirements. Keywords: Insecticide, Permethrin, CIPAC 3807&#x0D; &#x0D; Keywords: Insecticide, Permethrin, CIPAC 3807

Development and Validation of a SPE-HPLC Method for Quantification of Rhein, Emodin, Chrysophanol and Physcion in Rhamnus petiolaris Boiss. & Balansa.

Anthraquinones exhibit a significant group of natural and synthetic quinone derivatives because of their biological activities and industrial applications. Rhamnaceae is one of the families known to contain different kinds of anthraquinones. In this study, it was aimed to quantify rhein, emodin, chrysophanol and physcion in fruits of Rhamnus petiolaris Boiss. & Balansa belonging to Rhamnaceae by solid phase extraction and high performance liquid chromatography with ultraviolet detection. The anthraquinones were separated using a C18 analytical column. Gradient elution was performed using a mobile phase consisted of 0.1% o-phosphoric acid solution and methanol. Analytes were detected at 254nm. Calibration curves were prepared in the range of 0.25-5.00μg/mL for rhein, chrysophanol, physcion, 1.00-50.00μg/mL for emodin. Limits of detection and quantification were between 0.07-0.11 and 0.20-0.34μg/mL, respectively. Relative standard deviations were ≤ 5.78% in repeatability and intermediate precision studies. Accuracy was determined as relative mean error (8.17-12.06%). Extraction was achieved by maceration with acetone and ethanol, followed by hydrophilic-lipophilic balance solid phase extraction. Recoveries were between 96.2 and 109.6%. The developed and validated method was successfully performed to quantify rhein, emodin, chrysophanol and physcion in R. petiolaris fruit extracts. Only physcion was not detected above limit of detection.

An eco-friendly sample preparation procedure based on air-assisted liquid-liquid microextraction for the rapid determination of phthalate metabolites in urine samples by liquid chromatography-tandem mass spectrometry

Urinary phthalate metabolite (mPAEs) analysis is a reliable tool for assessing human exposure to phthalates. With growing interest in urinary biomonitoring of these metabolites, there is a need for fast and sensitive analytical methods. Therefore, a simple, rapid procedure for simultaneous determination of fifteen phthalate metabolites in human urine samples by liquid chromatography-tandem mass spectrometry was developed. The novelty of the present procedure is based on the use of diethyl carbonate as a green biobased extraction solvent and air-assisted liquid-liquid microextraction (AALLME) as a sample preparation step. A Plackett-Burman design was used for screening the factors that influence the AALLME extraction efficiency of mPAEs. The effective factors were then optimized by response surface methodology using a central composite rotatable design. Under the optimized conditions, good linearity can be achieved in a concentration range of 1.0–20.0 ng mL-1 with correlation coefficients higher than 0.99. The repeatability and reproducibility precision were in the range of 2–12% and 1–10% respectively. Recoveries ranging from 90% to 110%. This, and the low limits of detection, ranging from 0.01 to 0.05 ng mL-1, make the proposed procedure sensitive and suitable for human biomonitoring of phthalate exposures. For proof-of-principle, the new method was used to measure the urinary concentrations of mPAEs in 20 urine samples from Brazilian women. The high frequency of detections and in part high concentrations of mPAEs indicate to widespread exposure to several phthalates among Brazilian women.

A Novel Method for Filled/Unfilled Grain Classification Based on Structured Light Imaging and Improved PointNet+.

China is the largest producer and consumer of rice, and the classification of filled/unfilled rice grains is of great significance for rice breeding and genetic analysis. The traditional method for filled/unfilled rice grain identification was generally manual, which had the disadvantages of low efficiency, poor repeatability, and low precision. In this study, we have proposed a novel method for filled/unfilled grain classification based on structured light imaging and Improved PointNet++. Firstly, the 3D point cloud data of rice grains were obtained by structured light imaging. And then the specified processing algorithms were developed for the single grain segmentation, and data enhancement with normal vector. Finally, the PointNet++ network was improved by adding an additional Set Abstraction layer and combining the maximum pooling of normal vectors to realize filled/unfilled rice grain point cloud classification. To verify the model performance, the Improved PointNet++ was compared with six machine learning methods, PointNet and PointConv. The results showed that the optimal machine learning model is XGboost, with a classification accuracy of 91.99%, while the classification accuracy of Improved PointNet++ was 98.50% outperforming the PointNet 93.75% and PointConv 92.25%. In conclusion, this study has demonstrated a novel and effective method for filled/unfilled grain recognition.

Green and fast ultrasound-assisted extraction procedures for Fe, Mn, Mg and Ca analysis in cane syrups by FAAS

New methodologies for the analysis of Fe, Mn, Mg, and Ca content in cane syrups using FAAS combined with ultrasound-assisted extraction (UAE) were developed and validated. For multivariate optimization of UAE, a simplex-centroid mixture design and individual desirability functions were applied to achieve the best composition of extraction solvents (HNO3, HCl, and water). Under optimal conditions of ultrasound-assisted extraction (100 W, 37 kHz, 10 min, 5.0 mL of extraction solvent (ultrapure water for Fe and Mn and HNO3:H2O (75:25%, v/v), corresponding to a 1.19 mol L−1 HNO3 solution for Mg and Ca)), method validation showed good linearity, confirmed by regression analysis, and low LOD and LOQ values of 0.266–0.284 μg g−1 and 0.114–0.861 μg g−1. Estimates of repeatability and mean precision (RSD = 0.44–2.11%), Horrat values (0.07–0.26), and assessment of trueness by comparing sample preparation methods using a paired t-test demonstrated the excellent precision and trueness of the developed methods. The methods were applied to twenty-five cane syrup samples, and the results of the multivariate analysis showed that the metal ions can be used as indicators of geographical origin or contamination during manufacturing or processing, thus helping to ensure the food quality and safety of this sweetener.

Optimization of an Ultrasound-Assisted Extraction Method for the Extraction of Gingerols and Shogaols from Ginger (Zingiber officinale)

The goal of this study is to optimize a UAE method for the extraction of the main bioactive compounds present in the ginger rhizome (gingerols and shogaols). Ginger rhizome (Zingiber officinale) has a considerable content of bioactive compounds, in particular gingerols and shogaols, with interesting pharmacological activities such as anti-inflammatory, antioxidant, anti-cancer, and antimicrobial properties, among others. The isolation of these compounds requires an efficient extraction process with short extraction times and the employment of specific non-toxic solvents for humans. In this work, the optimization of an ultrasound-assisted extraction (UAE) method for the extraction of the main pungent compounds in the ginger rhizome, i.e., gingerols and shogaols, has been carried out. For this purpose, a Box–Behnken design (BBD) has been used to optimize the experimental design through a response surface methodology (RSM). The percentage of ethanol in the extraction solvent, the temperature, the amplitude, and the cycle of the ultrasounds, as well as the sample-to-solvent ratio, were the variables to be studied. Thus, the percentage of ethanol in the extraction solvent was identified as the most influential factor. Once the compounds were extracted, the identification of gingerols and shogaols was performed by ultra-high-performance liquid chromatography (UHPLC) coupled to a quadrupole-time-of-flight mass spectrometer (Q-ToF-MS), and the quantification by UHPLC coupled to a diode array detector (DAD) detector. Finally, the optimized UAE method required only 10 min of extraction time, presenting good repeatability and intermediate precision levels (&lt;5%). The method was applied to extract gingerols and shogaols from diverse sources, thereby demonstrating its applicability and highlighting the potential variations in compound concentrations across different samples based on factors such as origin, and growing conditions, among others.

Development and Validation of UV-Vis Spectrophotometric Method for Estimation of Amphotericin B from Hydrogel Nanoparticle

Abstract: Amphotericin B (AmB) is a polyene macrolide antibiotic that has antifungal action against the broadest range of fungal diseases as well as in some protozoan infections. There are currently no significant issues with resistance to AmB, and it is still in use today. The development of many innovative AmB formulations as lipid formulations and polymeric nanoparticles utilising UV-VIS spectrophotometry and HPLC technique has been discussed in the literature, however specifics of peak characteristics and validation data are not provided. The goal of this study was to provide an effective approach for validating AmB and to gather reliable, accurate, and consistent data on linearity, detection limit, quantification limit, accuracy, and precision using a UV-VIS spectrophotometer. The method gives a good linearity with regression of y = 0.1471x + 0.0489 (R2 = 0.9989) at 408 nm. The repeatability (inter-day) and intermediate precision (intra-day) precision studies revealed that the method is precise and reliable where all the RSD values were ˂2%. Method accuracy showed % accuracy value for all the three concentration levels ranged from 91.144 % to 101.994 % that a small change in the concentration of the drug could be accurately determined with high accuracy. Limit of detection and limit of quantification were 0.0295 (μg/ml) and 0.0895 (μg/ml) respectively. The suggested approach is straightforward and may be considered a strategy that is routinely practicable for estimating AmB.

Rapidly, sensitive quantitative assessment of thiopental via forced stability indicating validated RP-HPLC method and its in-use stability activities

Thiopental sodium (Tho) is an intravenous anesthetic. The current study aimed to find a rapid RP-HPLC method of Tho analysis with high linearity, repeatability, sensitivity, selectivity, and inexpensive. In our developed method, there is no need to use special chemical reagents, a high percentage of organic solvent, a high flow rate, or a further guard column. The chromatographic system consists of an ODS column (150 mm × 4.6 mm × 5 μm). The mobile phase was prepared by mixing KH2PO4 solution: methanol (40:60) with a flow rate of 1.2 mL/min at a detection wavelength of 230 nm, at room temperature using an injection volume of 10 μL. The method manifested a satisfied linearity regression R2 (0.9997) with a good repeatability precision range (0.16–0.47%) with LOD and LOQ; 14.4 μg/mL and 43.6 μg/mL respectively. Additionally, the method proved its efficiency via system suitability achievement in robustness and ruggedness, according to the validation guidelines. The shorter analysis time makes the method very valuable in quality control to quantify the commercial Tho in pharmaceutical preparations. This improved HPLC method has been successfully applied for Tho analysis for Thiopental UP Pharma 500 mg vials and Thiopental Eipico 1.0 g vials in our routine finished and stability studies testing laboratories. Additionally, the detection limit of Tho has been tested in our quality control lab to detect the smallest amount of traces that may be present after the cleaning process of the production machines for cephalosporins preparations. The method has shown positive results for Tho in low-level raw materials and pharmaceutical formulations.

Speedy Gonzales analysis method in one drop of beverage, for crimes committed with drugs from three different groups.

Sertraline, zolpidem and fentanyl, are drugs with potential to be used in cases of rape, property theft and organ theft. In this study, a 15min dilute-and-shoot analysis method was developed for the simultaneous confirmation and quantification of these drugs, using liquid chromatography tandem mass spectrometry (LC-MS/MS), in the residues of fruit juice types (mixed fruit juice, cherry juice and apricot juice), frequently consumed soft drinks. A C18phenomenex column (3µm × 100mm × 3mm) was used in LC-MS/MS analysis. Validation parameters were determined by means of linearity, linear range, LOD, LOQ, repeatability and intermediate precision studies. The linearity of the method was shown up to 2.0 μgmL-1 concentration and r2 was ≥ 0.99, for each analyte. LOD and LOQ values were found in the ranges of 4.9-10.2 and 13.0-57.5 ngmL-1 for all the analytes. Accuracies were between 74 and 126%. HorRat values calculated (between 0.57 and 0.97), revealed that the inter-day precisions (RSD% ≤ 15.5%) are acceptable. The simultaneous extraction and determination of these analytes in beverage residues in very low amounts as 100 µL is challenging because of the difficulty arising from the different chemical properties, the complexity of mixed fruit juice matrix. The method is important for hospitals (especially in emergency-toxicology cases), criminal and special laboratories from the point of determining the combined or single use of these drugs in drug facilitated crimes (DFC) and finding out the reasons of deaths related to these drugs.

Enzyme-catalyzed high-performing reaction with in-situ amplified photocurrent on carbon-functionalized inorganic photoanode for immunosensing

An enzyme-catalyzed high-performing reaction with in-situ amplified photocurrent was innovatively designed for the quantitative screening of carcinoembryonic antigen (CEA) in biological fluids by coupling with carbon-functionalized inorganic photoanode. A split-type photoelectrochemical (PEC) immunoassay was initially executed with horseradish peroxidase (HRP)-labeled secondary antibody on the capture antibody-coated microtiter. Then, the photocurrent of carbon-functionalized inorganic photoanode were improved through enzymatic insoluble product. Experimental results revealed that introduction of the outer carbon layer on the inorganic photoactive materials caused the amplifying photocurrent because of the improving light harvesting and separation of photo-generated e-/h+ pairs. Under optimum conditions, the split-type photoelectrochemical immunosensing platform displayed good photocurrent responses within the dynamic range of 0.01 – 80 ng mL-1 CEA, and allowed the detection of CEA as low as a concentration of 3.6 pg mL-1 at the 3Sblank level. The strong attachment of antibodies onto nano label and high-performing photoanode resulted in a good repeatability and intermediate precision down to 9.83%. No significant differences at the 0.05 significance level were encountered in the analysis of six human serum specimens between the developed PEC immunoassay and the commercially available CEA ELISA kits.

Enhancing the quantification accuracy for selected endocrine disruptors in different tea samples by GC–MS using matrix matching calibration strategy

This study was focused on enhancing the accuracy of quantifying twelve endocrine disruptors in green and black tea samples. The analytes included seven pesticides, two hormones, and three phenolic compounds. An optimized dispersive liquid–liquid microextraction method was used to preconcentrate the analytes from the tea samples for determination by gas chromatography-mass spectrometry. The matrix of the tea samples caused an enhancement effect on the extraction method and this yielded percent recoveries higher than 180% when calculated using the external calibration method. Matrix dilution and matrix matching calibration were used to prevent the formation of tea particle layers and enhance quantification accuracy, respectively. Similar tea matrices were used to prepare calibration standards and these were used to quantify the spiked analytes. The percent recovery results calculated for the analytes using matrix matching ranged between 92 and 105%. Both repeatability and reproducibility precision tests produced percent relative standard deviations below 10%.

Rapid method for determination of biogas composition by gas chromatography coupled to a thermal conductivity detector (GC-TCD)

ABSTRACT The search for alternative fuel sources to replace non-renewable energy is a highly relevant topic in current research studies. Both biomethane and biohydrogen can be obtained from several anaerobic biological processes, which have some advantages over traditional energy supply chains, especially due to the ability to use various wastes and/or wastewaters as feedstock for the biogas production, which is considered a renewable fuel. These features combined with low energy inputs support the potential of these processes to play a key role in replacing fossil energy sources in the coming decades, as well as helping to avoid climate changes. Thus, it is essential to accurately determine the composition of the biogas generated in different biological processes, regardless of the application: from lab-scale studies to industrial plants. In this work, a gas chromatography set consisting of a Shimadzu/TCD GC-2030 equipped with a Supelco Carboxen 1010PLOT column was used to determine hydrogen (H2), nitrogen (N2), methane (CH4) and dioxide carbon (CO2) by a low-cost manual injection procedure”. Two analytical curves (low and high ranges) were obtained for each target, which enables analysing biogas containing low and high concentrations of the targets. The validation parameters evaluated, namely, [i] linearity, working range, linear working range and sensitivity; [ii] limit of detection (LOD); [iii] limit of quantification (LOQ); and [iv] precision, expressed through repeatability and intermediate precision attested the reliability of the method for numerous applications.

Determination of Pinoresinol 4-O-beta-D-glucopyranoside and Vladinol F as Markers in Pandanus tonkinensis Fruits by High Performance Liquid Chromatography

According to the traditional know-how, the Northern wild pineapple (Pandanus tonkinensis) has been used efficiently as a major component of oriental remedies for liver protection. Based on the experimentally found chemical composition of Pandanus tonkinensis and their obtained biological activities in terms of the hepatoprotection purpose, two structure-elucidated compounds pinoresinol 4-O-beta-D-glucopyranoside and vladinol F were selected as potential markers for this medical plant. This paper is aiming to present the validation of proposed HPLC method for simultaneous quantification of the both pinoresinol 4-O-beta-D-glucopyranoside and vladinol F in the fruits of Pandanus tonkinensis with the following conditions: using RP-C18 (250 mm × 4.6 mm; 5 μm) column, detection wavelength measured at 228 nm, the mobile phases consisting of acetonitrile and 0.1% acetic acid in gradient mode with a flow rate of 1mL/min and injection volume was 10 mL. Method validation showed a high specificity, linear calibration ranging from 25.5 to 76.4 mg/ml (r= 0.9991) and from 26.0 to 77.9 mg/ml (r= 0.9987) for two markers, respectively. Besides, a good repeatability and intermediate precisions (RSD &lt; 2%), a reliable accuracy (recovery efficiency between 99.4 and 101.5%, RSD &lt; 1.73%) as well as the obtained limits of quantification in values of 2.55 m/g and 2.60 mg/g for the two mentioned markers were received. Using the above validated method, the content of two markers - pinoresinol 4-O-beta-D-glucopyranoside and vladinol F in Pandanus tonkinensis fruits collected from different locations (Thanh Hoa, Hoa Binh, Thai Nguyen) had been determined falling in the range of 0.0250 - 0.0435 mg/g and 0.0243 - 0.0371 mg/g, respectively.&#x0D; Keywords: pinoresinol 4-O-beta-D-glucopyranoside, vladinol F, markers, Pandanus tonkinensis, HPLC