Journal of Analytical Methods in Chemistry The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Rapid Screening Method for Detecting Ethinyl Estradiol in Natural Water Employing Voltammetry Wed, 21 Sep 2016 13:28:23 +0000 17α-Ethinyl estradiol (EE2), which is used worldwide in the treatment of some cancers and as a contraceptive, is often found in aquatic systems and is considered a pharmaceutically active compound (PhACs) in the environment. Current methods for the determination of this compound, such as chromatography, are expensive and lengthy and require large amounts of toxic organic solvents. In this work, a voltammetric procedure is developed and validated as a screening tool for detecting EE2 in water samples without prior extraction, clean-up, or derivatization steps. Application of the method we elaborate here to EE2 analysis is unprecedented. EE2 detection was carried out using differential pulse adsorptive cathodic stripping voltammetry (DP AdCSV) with a hanging mercury drop electrode (HMDE) in pH 7.0 Britton-Robinson buffer. The electrochemical process of EE2 reduction was investigated by cyclic voltammetry at different scan rates. Electroreduction of the hormone on a mercury electrode exhibited a peak at − V versus Ag/AgCl. The experimental parameters were as follows: −0.7 V accumulation potential, 150 s accumulation time, and 60 mV s−1 scan rate. The limit of detection was 0.49 μg L−1 for a preconcentration time of 150 s. Relative standard deviations were less than 13%. The method was applied to the detection of EE2 in water samples with recoveries ranging from 93.7 to 102.5%. Chalder Nogueira Nunes, Lucas Ely Pauluk, Maria Lurdes Felsner, Vanessa Egéa dos Anjos, and Sueli Pércio Quináia Copyright © 2016 Chalder Nogueira Nunes et al. All rights reserved. Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants Tue, 20 Sep 2016 16:39:23 +0000 HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from to %, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity () in the range of 2 to 100 ng g−1. The method also proved to be sensitive with low limits of detection (LODs) ranging from to  ng g−1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants. Thamani T. Gondo, Veronica C. Obuseng, Lesego C. Mmualefe, and Harriet Okatch Copyright © 2016 Thamani T. Gondo et al. All rights reserved. Analyses of Total Alkaloid Extract of Corydalis yanhusuo by Comprehensive RP × RP Liquid Chromatography with pH Difference Mon, 19 Sep 2016 06:21:07 +0000 A comprehensive two-dimensional (2D) reverse phase (RP) liquid chromatography (LC) method is developed for alkaloid analysis. This offline comprehensive 2D method is developed using different pH values. With a pH value of 10.5, most alkaloids appear in the form of neutral molecules possessing high retention factors based on their polarity, while the alkaloid polarity order is changed when the pH value decreased to 3.0. The performance of pH modulated 2D LC is demonstrated with 8 alkaloid standards which resulted in orthogonal separation. The developed method is then applied to total alkaloid separation in Corydalis yanhusuo. The first-dimension separation is carried out using methanol and water containing 1.0% ammonium hydroxide and a strong base-resistant RP column, which afforded a peak capacity of 94. The second-dimension analysis is carried out with a surface positive charge column providing a peak capacity of 205 using a mobile phase consisting of acetonitrile and water with 0.15% formic acid. 2D analyses of total alkaloid extract from C. yanhusuo afford a total peak capacity of 9090. Sixteen compounds were tentatively identified based on their ultraviolet spectrum and MS/MS analyses. The proposed method provides an alternative approach to achieve high peak capacity for analysis of alkaloid extract. Xiaodong Wei, Hongling Shen, Lijun Wang, Qingyan Meng, and Wenjie Liu Copyright © 2016 Xiaodong Wei et al. All rights reserved. Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples Thu, 08 Sep 2016 17:36:38 +0000 Polythiophene/chitosan magnetic nanocomposite as an adsorbent of magnetic solid phase extraction was proposed for the isolation of fluoxetine in aqueous and biological samples prior to fluorescence detection at 246 nm. The synthesized nanoparticles, chitosan and polythiophene magnetic nanocomposite, were characterized by scanning electron microscopy, FT-IR, TGA, and EDAX. The separation of the target analyte from the aqueous solution containing the fluoxetine and polythiophene/chitosan magnetic nanocomposite was simply achieved by applying external magnetic field. The main factors affecting the extraction efficiency including desorption conditions, extraction time, ionic strength, and sample solution pH were optimized. The optimum extraction conditions were obtained as 10 min for extraction time, 25 mg for sorbent amount, 50 mL for initial sample volume, methanol as desorption solvent, 1.5 mL for desorption solvent volume, 3 min for desorption time, and being without salt addition. Under the optimum conditions, good linearity was obtained within the range of 15–1000 μg L−1 for fluoxetine, with correlation coefficients 0.9994. Furthermore, the method was successfully applied to the determination of fluoxetine in urine and human blood plasma samples. Compared with other methods, the current method is characterized with highly easy, fast separation and low detection limits. Alireza Feizbakhsh, Amir Hossein Mohsen Sarrafi, and Shokooh Ehteshami Copyright © 2016 Alireza Feizbakhsh et al. All rights reserved. Capitalizing Resolving Power of Density Gradient Ultracentrifugation by Freezing and Precisely Slicing Centrifuged Solution: Enabling Identification of Complex Proteins from Mitochondria by Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Wed, 07 Sep 2016 16:50:12 +0000 Density gradient centrifugation is widely utilized for various high purity sample preparations, and density gradient ultracentrifugation (DGU) is often used for more resolution-demanding purification of organelles and protein complexes. Accurately locating different isopycnic layers and precisely extracting solutions from these layers play a critical role in achieving high-resolution DGU separations. In this technique note, we develop a DGU procedure by freezing the solution rapidly (but gently) after centrifugation to fix the resolved layers and by slicing the frozen solution to fractionate the sample. Because the thickness of each slice can be controlled to be as thin as 10 micrometers, we retain virtually all the resolution produced by DGU. To demonstrate the effectiveness of this method, we fractionate complex V from HeLa mitochondria using a conventional technique and this freezing-slicing (F-S) method. The comparison indicates that our F-S method can reduce complex V layer thicknesses by ~40%. After fractionation, we analyze complex V proteins directly on a matrix assisted laser desorption/ionization, time-of-flight mass spectrometer. Twelve out of fifteen subunits of complex V are positively identified. Our method provides a practical protocol to identify proteins from complexes, which is useful to investigate biomolecular complexes and pathways in various conditions and cell types. Haiqing Yu, Joann J. Lu, Wei Rao, and Shaorong Liu Copyright © 2016 Haiqing Yu et al. All rights reserved. Ripening-Dependent Changes in Antioxidants, Color Attributes, and Antioxidant Activity of Seven Tomato (Solanum lycopersicum L.) Cultivars Wed, 07 Sep 2016 10:09:04 +0000 To evaluate the ripening-dependent changes in phytonutrients, seven commercial cultivars (two general and five cherry) of tomatoes were cultivated under greenhouse conditions. Fruits were harvested at breaker, turning, pink, light red, and red stages of each cultivar, and antioxidant contents, color attributes, and antioxidant activities were measured. During ripening process, lycopene content increased from the breaker to red stage, while lutein displayed the reverse accumulation pattern, with higher values during the breaker stage. In contrast, -carotene showed the highest levels of synthesis in pink and light red stages. Furthermore, flavonoids (quercetin, rutin, naringenin, and luteolin) also showed similar ripening-dependent changes, with higher quantities in pink and light red stages. Ascorbic acid showed continuously increasing patterns throughout ripening until the red stage, while the accumulation of total phenolics was cultivar-dependent. These results indicate that each antioxidant compound has a unique pattern of accumulation and degradation during the ripening process. “Unicon” exhibited highest total carotenoid (110.27 mg/100 g), total phenol (297.88 mg GAE/100 g) and total flavonoid content (273.33 mg/100 g), and consequently highest antioxidant activity (2552.4 μmol TE/100 g) compared to other cultivars. Throughout the ripening processes, total phenolics showed the highest correlation with antioxidant activity, followed by -carotene and total flavonoids. In conclusion, ripening in tomatoes is accompanied by incremental increases in various antioxidant compounds to some extent, as well as by concomitant increases in antioxidant activity. Shiva Ram Bhandari and Jun Gu Lee Copyright © 2016 Shiva Ram Bhandari and Jun Gu Lee. All rights reserved. Direct Comparison of 19F qNMR and 1H qNMR by Characterizing Atorvastatin Calcium Content Thu, 01 Sep 2016 06:45:47 +0000 Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes. Yang Liu, Zhaoxia Liu, Huaxin Yang, and Lan He Copyright © 2016 Yang Liu et al. All rights reserved. Determination of Very Low Level of Free Formaldehyde in Liquid Detergents and Cosmetic Products Using Photoluminescence Method Sun, 21 Aug 2016 14:42:22 +0000 Formaldehyde is commonly used in detergents and cosmetic products as antibacterial agent and preservative. This substance is unfavorable for human health because it is known to be toxic for humans and causes irritation of eyes and skins. The toxicology studies of this compound indicate risk of detergents and cosmetic formulations with a minimum content of 0.05% free formaldehyde. Therefore, determination of formaldehyde as quality control parameter is very important. In this study, a photoluminescence method was achieved by using 2-methyl acetoacetanilide. Also, the Box-Behnken design was applied for optimization of Hantzsch reaction for formaldehyde derivatization. The investigated factors (variables) were temperature, % v/v ethanol, reaction time, ammonium acetate, and 2-methyl acetoacetanilide concentration. The linear range was obtained from 0.33–20 × 10−7 M (1–60 μg·kg−1) and the limit of detection (LOD) was 0.12 μg·kg−1. The proposed method was applied for the analysis of Iranian brands of liquid detergents and cosmetic products. The formaldehyde content of these products was found to be in the range of 0.03–3.88%. Some brands of these products had higher concentration than the maximum allowed concentration of 0.2%. High recoveries (96.15%–104.82%) for the spiked dishwashing liquid and hair shampoo indicate the proposed method is proper for the assessment of formaldehyde in detergents and cosmetic products. The proposed methodology has some advantages compared with the previous methods such as being rapid, without the necessity of applying separation, low cost, and the fact that the derivatization reaction is carried out at room temperature without any heating system. Ali Gholami, Atefeh Mohsenikia, and Saeed Masoum Copyright © 2016 Ali Gholami et al. All rights reserved. A Study on the Reliability of an On-Site Oral Fluid Drug Test in a Recreational Context Wed, 17 Aug 2016 12:02:12 +0000 The reliability of DrugWipe 5A on site test for principal drugs of abuse (cannabis, amphetamines, cocaine, and opiates) detection in oral fluid was assessed by comparing the on-site results with headspace solid-phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS) analysis on samples extracted by the device collection pad. Oral fluid samples were collected at recreational settings (e.g., discos, pubs, and music bars) of Rome metropolitan area. Eighty-three club goers underwent the on-site drug screening test with one device. Independently from the result obtained, a second device was used just to collect another oral fluid sample subsequently extracted and analyzed in the laboratory following HS-SPME procedure, gas chromatographic separation by a capillary column, and MS detection by electron impact ionization. DrugWipe 5A on-site test showed 54 samples (65.1%) positive to one or more drugs of abuse, whereas 75 samples (90.4%) tested positive for one or more substances following GC-MS assay. Comparing the obtained results, the device showed sensitivity, specificity, and accuracy around 80% for amphetamines class. Sensitivity (67 and 50%) was obtained for cocaine and opiates, while both sensitivity and accuracy were unsuccessful (29 and 53%, resp.) for cannabis, underlying the limitation of the device for this latter drug class. Stefano Gentili, Renata Solimini, Roberta Tittarelli, Giulio Mannocchi, and Francesco Paolo Busardò Copyright © 2016 Stefano Gentili et al. All rights reserved. Isolation and Analysis of Phospholipids in Dairy Foods Wed, 17 Aug 2016 09:50:32 +0000 The lipid fraction of milk is one of the most complex matrixes in foodstuffs due to the presence of a high number of moieties with different physical and chemical properties. Glycerolipids include glycerol and two fatty acids esterified in positions sn-1 and sn-2 with higher concentration of unsaturated fatty acids than in the triglyceride fraction of milk. Sphingolipids consist of a sphingoid base linked to a fatty acid across an amide bond. Their amphiphilic nature makes them suitable to be added into a variety of foods and recent investigations show that phospholipids, mainly phosphatidylserine and sphingomyelin, can exert antimicrobial, antiviral, and anticancer activities as well as positive effects in Alzheimer’s disease, stress, and memory decline. Polar lipids can be found as natural constituents in the membranes of all living organisms with soybean and eggs as the principal industrial sources, yet they have low contents in phosphatidylserine and sphingomyelin. Animal products are rich sources of these compounds but since there are legal restrictions to avoid transmission of prions, milk and dairy products are gaining interest as alternative sources. This review summarizes the analysis of polar lipids in dairy products including sample preparation (extraction and fractionation/isolation) and analysis by GC or HPLC and the latest research works using ELSD, CAD, and MS detectors. Lígia Pimentel, Ana Gomes, Manuela Pintado, and Luis Miguel Rodríguez-Alcalá Copyright © 2016 Lígia Pimentel et al. All rights reserved. Selective and Accurate Determination Method of Propofol in Human Plasma by Mixed-Mode Cation Exchange Cartridge and GC-MS Thu, 11 Aug 2016 14:12:17 +0000 A gas chromatography-mass spectrometry (GC-MS) method for the determination of propofol in human plasma has been developed and validated. Propofol was extracted from human plasma by using mixed-mode cation exchange/reversed-phase (MCX) cartridges. As propofol easily volatilizes during concentration, 100% methanol was injected directly into GC-MS to elute propofol. Despite avoiding concentration process of the eluted solution, lower limit of quantization (LLOQ) of propofol was 25 ng/mL. The validated method exhibited good linearity () with accuracy and precision −5.8%~11.7% and 3.7%~11.6%, respectively. The other validation parameters, recovery and matrix effect, ranged from 96.6% to 99.4% and 95.3% to 101.4%, respectively. Propofol standard was quantified to evaluate possible loss due to the concentration processes, nitrogen gas and centrifugal vacuum. These two concentration processes resulted in notable decrease in the quantity of propofol, signifying avoiding any concentration processes during propofol quantification. Also, to confirm suitability of the developed method, authentic human plasma samples were analyzed. The selective assay method using MCX cartridge and GC-MS facilitated quantification of propofol in plasma sample accurately by preventing any losses due to the concentration processes. Jae Sung Pyo Copyright © 2016 Jae Sung Pyo. All rights reserved. A Confirmatory Method Based on HPLC-MS/MS for the Detection and Quantification of Residue of Tetracyclines in Nonmedicated Feed Tue, 09 Aug 2016 15:33:23 +0000 The Commission Regulation 574/2011/EC set up maximum levels of coccidiostats and histomonostats in nonmedicated feed as a consequence of carry-over during manufacturing. Carry-over takes place from medicated to nonmedicated feed during feed production. Similar contamination could also occur for other pharmaceuticals such as tetracyclines, a group of antibiotics commonly employed in food production animal. The objective of this work is to present a simple and fast method for the simultaneous detection of four tetracyclines (chlortetracycline, doxycycline, oxytetracycline, and tetracycline) in nontarget feed at a μg/kg level. Validation of the method was performed according to the guideline included in the Commission Decision 2002/657/EC for official method. The validated method was successfully applied to 50 feed samples collected from different milk farms and 25 samples obtained from feed manufacturers. While oxytetracycline was the tetracycline most frequently detected, chlortetracycline was the analyte measured at the highest concentration 15.14 mg/Kg. From 75 nonmedicated feed analysed 15% resulted to be positive for the presence of one tetracycline. Rosa E. Gavilán, Carolina Nebot, Maria Veiga-Gómez, Paula Roca-Saavedra, Beatriz Vazquez Belda, Carlos M. Franco, and Alberto Cepeda Copyright © 2016 Rosa E. Gavilán et al. All rights reserved. Comparative Pharmacokinetics and Bioavailability of Epimedin C in Rat after Intramuscular Administration of Epimedin C, a Combination of Four Flavonoid Glycosides and Purified Herba Epimedii Extract Tue, 09 Aug 2016 07:21:37 +0000 Chuan-Ke-Zhi (CKZ), a purified Herba Epimedii extract, is a potent Chinese medicine preparation whose main bioactive components are a class of flavonoid glycosides such as epimedins A, B, and C and icariin. And epimedin C is far more abundant than other flavones in this extract. This study aims to investigate the pharmacokinetic and bioavailability of epimedin C and what effects, if any, other ingredients in CKZ have on its pharmacokinetics. Epimedin C, CKZ, and a combination of epimedins A, B, and C and icariin were, respectively, administrated to rats, and then the pharmacokinetic parameters of epimedin C in the three groups were calculated and compared. The result indicated that , , and of epimedin C were significantly different among the three groups (), and compared with the epimedin C group, the absorption of epimedin C significantly increased in the CKZ group. Furthermore, in this study the absolute bioavailability of epimedin C was also investigated by comparing intramuscular and intravenous administration of epimedin C. As a result, epimedin C could be quickly absorbed with extremely high absolute bioavailability after intramuscular administration. Shunjun Xu, Jiejing Yu, Liu Yang, Yaling Zhu, Shuai Sun, and Zhengdi Xu Copyright © 2016 Shunjun Xu et al. All rights reserved. Influence of Polyphosphoric Acid on the Consistency and Composition of Formulated Bitumen: Standard Characterization and NMR Insights Mon, 08 Aug 2016 09:45:21 +0000 Over the recent years, bitumen modification with polymers, acids, or mineral fillers has gained relevance to adjust its performance properties. This work reports the use of polyphosphoric acid (PPA) for the modification of formulated bitumen. With this objective, an in-depth literature review on PPA modification was firstly performed. Subsequently, five individual refinery components were selected for the preparation of bitumen blends, namely, asphaltic residue, vacuum residue, and three lube oils extracts. Seven binary/ternary bitumen blends were prepared and then treated with PPA. Afterwards, the five components and the unmodified and PPA-modified bitumen were characterized by standard methods (penetration, softening point, and penetration index), SARA analysis, elemental analysis, and 31P and 1H nuclear magnetic resonance (NMR) spectroscopy. The results evidenced higher asphaltenes and lower saturates/resins contents in PPA-modified bitumen. The NMR data suggest that the paraffinic chains became longer, the content of condensed aromatics increased, more substituted aromatic structures appeared, and -hydrogen in aromatic structures diminished. These findings disclosed the improved consistency and oxidation stability of PPA-modified bitumen blends. Catarina Varanda, Inês Portugal, Jorge Ribeiro, Artur M. S. Silva, and Carlos M. Silva Copyright © 2016 Catarina Varanda et al. All rights reserved. Model Analytical Development for Physical, Chemical, and Biological Characterization of Momordica charantia Vegetable Drug Sun, 07 Aug 2016 06:41:31 +0000 Momordica charantia is a species cultivated throughout the world and widely used in folk medicine, and its medicinal benefits are well documented, especially its pharmacological properties, including antimicrobial activities. Analytical methods have been used to aid in the characterization of compounds derived from plant drug extracts and their products. This paper developed a methodological model to evaluate the integrity of the vegetable drug M. charantia in different particle sizes, using different analytical methods. M. charantia was collected in the semiarid region of Paraíba, Brazil. The herbal medicine raw material derived from the leaves and fruits in different particle sizes was analyzed using thermoanalytical techniques as thermogravimetry (TG) and differential thermal analysis (DTA), pyrolysis coupled to gas chromatography/mass spectrometry (PYR-GC/MS), and nuclear magnetic resonance (1H NMR), in addition to the determination of antimicrobial activity. The different particle surface area among the samples was differentiated by the techniques. DTA and TG were used for assessing thermal and kinetic parameters and PYR-GC/MS was used for degradation products chromatographic identification through the pyrograms. The infusions obtained from the fruit and leaves of Momordica charantia presented antimicrobial activity. Deysiane Oliveira Brandão, Geovani Pereira Guimarães, Ravely Lucena Santos, Fernando José de Lima Ramos Júnior, Karla Monik Alves da Silva, Fabio Santos de Souza, and Rui Oliveira Macêdo Copyright © 2016 Deysiane Oliveira Brandão et al. All rights reserved. Extraction Efficiency of Different Solvents and LC-UV Determination of Biogenic Amines in Tea Leaves and Infusions Sun, 31 Jul 2016 16:53:13 +0000 Biogenic amines (BAs), that is, spermine, spermidine, putrescine, histamine, tyramine, β-phenylethylamine, cadaverine, and serotonin, have been determined in several samples of tea leaves, tea infusions, and tea drinks by LC-UV method after derivatization with dansyl chloride. Different extraction solvents have been tested and TCA 5% showed better analytical performances in terms of linearity, recovery percentages, LOD, LOQ, and repeatability than HCl 0.1 M and HClO4 0.1 M and was finally exploited for the quantitative determination of BAs in all samples. In tea leaves total BAs concentration ranged from 2.23 μg g−1 to 11.24 μg g−1 and PUT (1.05–2.25 μg g−1) and SPD (1.01–1.95 μg g−1) were always present, while SER (nd–1.56 μg g−1), HIS (nd–2.44 μg g−1), and SPM (nd–1.64 μg g−1) were detected more rarely. CAD and PHE were determined in few samples at much lower concentrations while none of the samples contained TYR. Tea infusions showed the same trend with total BAs concentrations never exceeding 80.7 μg L−1. Black teas showed higher amounts of BAs than green teas and organic and decaffeinated samples always contained much lower BAs levels than their conventional counterparts. U. Gianfranco Spizzirri, Nevio Picci, and Donatella Restuccia Copyright © 2016 U. Gianfranco Spizzirri et al. All rights reserved. Authentication of Coffea arabica according to Triacylglycerol Stereospecific Composition Thu, 28 Jul 2016 12:50:04 +0000 Stereospecific analysis is an important tool for the characterization of lipid fraction of food products. In the present research, an approach to characterize arabica and robusta varieties by structural analysis of the triacylglycerol (TAG) fraction is reported. The lipids were Soxhlet extracted from ground roasted coffee beans with petroleum ether, and the fatty acids (FA) were determined as their corresponding methyl esters. The results of a chemical-enzymatic-chromatographic method were elaborated by a chemometric procedure, Linear Discriminant Analysis (LDA). According to the total and intrapositional FA composition of TAG fraction, the obtained results were able to characterize roasted pure coffee samples and coffee mixtures with 10% robusta coffee added to arabica coffee. Totally correct classified samples were obtained when the TAG stereospecific results of the considered coffee mixture (90 : 10 arabica/robusta) were elaborated by LDA procedure. L. Cossignani, D. Montesano, M. S. Simonetti, and F. Blasi Copyright © 2016 L. Cossignani et al. All rights reserved. Analysis of Flavonoid in Medicinal Plant Extract Using Infrared Spectroscopy and Chemometrics Tue, 26 Jul 2016 14:17:54 +0000 Infrared (IR) spectroscopy combined with chemometrics has been developed for simple analysis of flavonoid in the medicinal plant extract. Flavonoid was extracted from medicinal plant leaves by ultrasonication and maceration. IR spectra of selected medicinal plant extract were correlated with flavonoid content using chemometrics. The chemometric method used for calibration analysis was Partial Last Square (PLS) and the methods used for classification analysis were Linear Discriminant Analysis (LDA), Soft Independent Modelling of Class Analogies (SIMCA), and Support Vector Machines (SVM). In this study, the calibration of NIR model that showed best calibration with and RMSEC value was 0.9916499 and 2.1521897, respectively, while the accuracy of all classification models (LDA, SIMCA, and SVM) was 100%. and RMSEC of calibration of FTIR model were 0.8653689 and 8.8958149, respectively, while the accuracy of LDA, SIMCA, and SVM was 86.0%, 91.2%, and 77.3%, respectively. PLS and LDA of NIR models were further used to predict unknown flavonoid content in commercial samples. Using these models, the significance of flavonoid content that has been measured by NIR and UV-Vis spectrophotometry was evaluated with paired samples -test. The flavonoid content that has been measured with both methods gave no significant difference. Lestyo Wulandari, Yuni Retnaningtyas, Nuri, and Hilmia Lukman Copyright © 2016 Lestyo Wulandari et al. All rights reserved. Rapid Quantification of Melamine in Different Brands/Types of Milk Powders Using Standard Addition Net Analyte Signal and Near-Infrared Spectroscopy Wed, 20 Jul 2016 07:17:20 +0000 Multivariate calibration (MVC) and near-infrared (NIR) spectroscopy have demonstrated potential for rapid analysis of melamine in various dairy products. However, the practical application of ordinary MVC can be largely restricted because the prediction of a new sample from an uncalibrated batch would be subject to a significant bias due to matrix effect. In this study, the feasibility of using NIR spectroscopy and the standard addition (SA) net analyte signal (NAS) method (SANAS) for rapid quantification of melamine in different brands/types of milk powders was investigated. In SANAS, the NAS vector of melamine in an unknown sample as well as in a series of samples added with melamine standards was calculated and then the Euclidean norms of series standards were used to build a straightforward univariate regression model. The analysis results of 10 different brands/types of milk powders with melamine levels 0~0.12% (w/w) indicate that SANAS obtained accurate results with the root mean squared error of prediction (RMSEP) values ranging from 0.0012 to 0.0029. An additional advantage of NAS is to visualize and control the possible unwanted variations during standard addition. The proposed method will provide a practically useful tool for rapid and nondestructive quantification of melamine in different brands/types of milk powders. Bang-Cheng Tang, Chen-Bo Cai, Wei Shi, and Lu Xu Copyright © 2016 Bang-Cheng Tang et al. All rights reserved. The Determination of Protonation Constants of Peptidomimetic Cyclophanes in Binary Methanol-Water Mixtures Mon, 18 Jul 2016 15:50:35 +0000 The protonation constants of new group of peptidomimetic cyclophanes with valine or phenylalanine moieties incorporated into the macrocyclic skeleton as well as their linear analogues were determined by potentiometric measurements in solutions of methanol-water mixtures at 25°C and constant ionic strength. The influence of cavity size, location of protonation sites, and attached substituents of the macrocyclic ligands on the protonation constants were discussed on the basis of potentiometric measurement as well as H1-NMR results. Piotr Seliger, Danuta Tomczyk, Grzegorz Andrijewski, and Ewa Tomal Copyright © 2016 Piotr Seliger et al. All rights reserved. Classification of Coffee Beans by GC-C-IRMS, GC-MS, and 1H-NMR Mon, 18 Jul 2016 09:35:53 +0000 In a previous work using 1H-NMR we reported encouraging steps towards the construction of a robust expert system for the discrimination of coffees from Colombia versus nearby countries (Brazil and Peru), to assist the recent protected geographical indication granted to Colombian coffee in 2007. This system relies on fingerprints acquired on a 400 MHz magnet and is thus well suited for small scale random screening of samples obtained at resellers or coffee shops. However, this approach cannot easily be implemented at harbour’s installations, due to the elevated operational costs of cryogenic magnets. This limitation implies shipping the samples to the NMR laboratory, making the overall approach slower and thereby more expensive and less attractive for large scale screening at harbours. In this work, we report on our attempt to obtain comparable classification results using alternative techniques that have been reported promising as an alternative to NMR: GC-MS and GC-C-IRMS. Although statistically significant information could be obtained by all three methods, the results show that the quality of the classifiers depends mainly on the number of variables included in the analysis; hence NMR provides an advantage since more molecules are detected to obtain a model with better predictions. Victoria Andrea Arana, Jessica Medina, Pierre Esseiva, Diego Pazos, and Julien Wist Copyright © 2016 Victoria Andrea Arana et al. All rights reserved. A New Local Modelling Approach Based on Predicted Errors for Near-Infrared Spectral Analysis Thu, 30 Jun 2016 12:34:17 +0000 Over the last decade, near-infrared spectroscopy, together with the use of chemometrics models, has been widely employed as an analytical tool in several industries. However, most chemical processes or analytes are multivariate and nonlinear in nature. To solve this problem, local errors regression method is presented in order to build an accurate calibration model in this paper, where a calibration subset is selected by a new similarity criterion which takes the full information of spectra, chemical property, and predicted errors. After the selection of calibration subset, the partial least squares regression is applied to build calibration model. The performance of the proposed method is demonstrated through a near-infrared spectroscopy dataset of pharmaceutical tablets. Compared with other local strategies with different similarity criterions, it has been shown that the proposed local errors regression can result in a significant improvement in terms of both prediction ability and calculation speed. Haitao Chang, Lianqing Zhu, Xiaoping Lou, Xiaochen Meng, Yangkuan Guo, and Zhongyu Wang Copyright © 2016 Haitao Chang et al. All rights reserved. Analysis of E. rutaecarpa Alkaloids Constituents In Vitro and In Vivo by UPLC-Q-TOF-MS Combined with Diagnostic Fragment Thu, 30 Jun 2016 11:19:27 +0000 Evodia rutaecarpa (Juss.) Benth. (Rutaceae) dried ripe fruit is used for dispelling colds, soothing liver, and analgesia. Pharmacological research has proved that alkaloids are the main active ingredients of E. rutaecarpa. This study aimed to rapidly classify and identify the alkaloids constituents of E. rutaecarpa by using UPLC-Q-TOF-MS coupled with diagnostic fragments. Furthermore, the effects of the material base of E. rutaecarpa bioactive ingredients in vivo were examined such that the transitional components in the blood of rats intragastrically given E. rutaecarpa were analyzed and identified. In this study, the type of alcohol extraction of E. rutaecarpa and the corresponding blood sample were used for the analysis by UPLC-Q-TOF-MS in positive ion mode. After reviewing much of the literature and collected information on the fragments, we obtained some diagnostic fragments of the alkaloids. Combining the diagnostic fragments with the technology of UPLC-Q-TOF-MS, we identified the compounds of E. rutaecarpa and blood samples and compared the ion fragment information with that of the alkaloids in E. rutaecarpa. A total of 17 alkaloids components and 6 blood components were identified. The proposed method was rapid, accurate, and sensitive. Therefore, this technique can reliably and practically analyze the chemical constituents in traditional Chinese medicine (TCM). Shenshen Yang, Meng Tian, Lei Yuan, Haoyue Deng, Lei Wang, Aizhu Li, Zhiguo Hou, Yubo Li, and Yanjun Zhang Copyright © 2016 Shenshen Yang et al. All rights reserved. The Verification of the Usefulness of Electronic Nose Based on Ultra-Fast Gas Chromatography and Four Different Chemometric Methods for Rapid Analysis of Spirit Beverages Wed, 29 Jun 2016 15:12:19 +0000 Spirit beverages are a diverse group of foodstuffs. They are very often counterfeited which cause the appearance of low quality products or wrongly labelled products on the market. It is important to find a proper quality control and botanical origin method enabling the same time preliminary check of the composition of investigated samples, which was the main goal of this work. For this purpose, the usefulness of electronic nose based on ultra-fast gas chromatography (fast GC e-nose) was verified. A set of 24 samples of raw spirits, 33 samples of vodkas, and 8 samples of whisky were analysed by fast GC e-nose. Four data analysis methods were used. The PCA was applied for the visualization of dataset, observation of the variation inside groups of samples, and selection of variables for the other three statistical methods. The SQC method was utilized to compare the quality of the samples. Both the DFA and SIMCA data analysis methods were used for discrimination of vodka, whisky, and spirits samples. The fast GC e-nose combined with four statistical methods can be used for rapid discrimination of raw spirits, vodkas, and whisky and in the same for preliminary determination of the composition of investigated samples. Paulina Wiśniewska, Magdalena Śliwińska, Jacek Namieśnik, Waldemar Wardencki, and Tomasz Dymerski Copyright © 2016 Paulina Wiśniewska et al. All rights reserved. Quality Evaluation of Polar and Active Components in Crude and Processed Fructus Corni by Quantitative Analysis of Multicomponents with Single Marker Wed, 29 Jun 2016 14:57:02 +0000 Objective. To develop a quantitative analysis of multicomponents by single-marker (QAMS) method for the simultaneous determination of polar active components in Fructus Corni. Methods. Loganin was selected as the internal reference, and the relative correction factors (RCFs) of gallic acid, 5-hydroxymethyl-2-furfural, morroniside, sweroside, cornin, 7α-O-methylmorroniside, 7β-O-methylmorroniside, 7α-O-ethylmorroniside, 7β-O-ethylmorroniside, and cornuside were established. The contents of multicomponents were then calculated based on their RCFs, respectively. Contents of the 11 components were also calculated by external standard method and compared with those of the QAMS method. Results. The contents of the 11 components in 21 crude and 10 processed Fructus Corni products were measured. No significant difference was found in the quantitative results of the QAMS and external standard methods. Conclusion. QAMS could serve as an accurate and convenient method in determining the polar and active components in Fructus Corni and its processed products. Yuhong Jiang, Hui Chen, Liling Wang, Jing Zou, Xiao Zheng, and Zhihui Liu Copyright © 2016 Yuhong Jiang et al. All rights reserved. Determination of Total Apigenin in Herbs by Micellar Electrokinetic Chromatography with UV Detection Wed, 29 Jun 2016 13:37:20 +0000 Apigenin is a naturally occurring plant flavone that exhibits strong antioxidant, anti-inflammatory, and antitumor properties. A MEKC-UV based method was developed for the determination of total apigenin in selected herbs. Application of pseudostationary phase in the form of SDS micelles resulted in great repeatability of retention times and peak areas. A buffer solution consisting of 30 mmol/L sodium borate (pH 10.2), 10% acetonitrile, and 10 mmol/L sodium dodecyl sulfate was found to be the most suitable BGE for the separation. The method was validated and calibrated for total apigenin in the range of 1.0–100 μmol/L (). The limits of detection and quantification were 0.48 μmol/L and 0.92 μmol/L, respectively. This precise and robust method was successfully applied to the analysis of plant samples for total apigenin content. Rafał Głowacki, Paulina Furmaniak, Paweł Kubalczyk, and Kamila Borowczyk Copyright © 2016 Rafał Głowacki et al. All rights reserved. Magnetic Solid-Phase Extraction Based on β-Cyclodextrins/Acrylic Acid Modified Magnetic Gelatin for Determination of Moxidectin in Milk Samples Wed, 29 Jun 2016 09:47:45 +0000 β-Cyclodextrins/acrylic acid modified magnetic gelatin was prepared and then employed as the magnetic solid-phase extraction (MSPE) sorbent for extraction of moxidectin in milk samples. Due to the rigidity of hydrophobic cavity of β-cyclodextrins and carboxyl groups of acrylic acid, magnetic composites are prepared to form a complex with target molecules through various kinds of chemical reactions and then showed excellent extraction performance. This method exhibits the advantages of simplicity of implementation, short extraction time (5 min), low solvent consumption, and high extraction efficiency. A rapid, simple, and effective method for the analysis of moxidectin in milk samples was established by MSPE coupled with liquid chromatography-fluorescence detection. The limit of detection was 0.1 ng·mL−1 and the recoveries from milk samples were in the range of 93.8%–112.5%. The relative standard deviation was not higher than 6.4%. In conclusion, magnetic solid-phase extraction is a simple and robust preconcentration technique that can be coupled to other analytical methods for the quantitative determination of target molecules in complex samples. Yinzhu Shang, Jing Luo, Peng Wang, Xiaoya Zhao, Cheng Ye, and Shaofei Guo Copyright © 2016 Yinzhu Shang et al. All rights reserved. Application of Hydrophilic Interaction Liquid Chromatography for the Quantification of Flavonoids in Genista tinctoria Extract Tue, 28 Jun 2016 15:06:58 +0000 Hydrophilic interaction chromatography (HILIC) was employed to investigate chromatographic behavior of selected flavonoids from their different subgroups differing in polarity. Chromatographic measurements were performed on two different HILIC columns: unmodified silica (Atlantis-HILIC) and zwitterionic sulfoalkylbetaine (SeQuant ZIC-HILIC). Separation parameters such as content and type of organic modifier were studied. On ZIC column retention factors were observed to be inversely proportional to the buffer content in the mobile phase, which is the typical partitioning mechanism. In the case of bare silica column more or less apparent dual retention mechanism was observed, depending on the water component content in the mobile phase. ZIC-HILIC showed better selectivity (in comparison to silica column) with the detection limit of 0.01 mg/L (only for rutin was 0.05 mg/L). Finally, this chromatographic procedure was validated and applied for the determination of some flavonoids in Genista tinctoria L. extract. Aleksandra Sentkowska, Magdalena Biesaga, and Krystyna Pyrzynska Copyright © 2016 Aleksandra Sentkowska et al. All rights reserved. Spectroscopic Characteristics of Dissolved Organic Matter in Afforestation Forest Soil of Miyun District, Beijing Tue, 28 Jun 2016 15:03:23 +0000 In this study, soil samples collected from different plain afforestation time (1 year, 4 years, 10 years, 15 years, and 20 years) in Miyun were characterized, including total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), available K (K+), microbial biomass carbon (MBC), and dissolved organic carbon (DOC). The DOM in the soil samples with different afforestation time was further characterized via DOC, UV-Visible spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy, and 1H NMR spectroscopy. The results suggested that the texture of soil sample was sandy. The extracted DOM from soil consisted mainly of aliphatic chains and only a minor aromatic component. It can be included that afforestation can improve the soil quality to some extent, which can be partly reflected from the indexes like TOC, TN, TP, K+, MBC, and DOC. And the characterization of DOM implied that UV humic-like substances were the major fluorophores components in the DOM of the soil samples, which consisted of aliphatic chains and aromatic components with carbonyl, carboxyl, and hydroxyl groups. Shi-Jie Gao, Chen Zhao, Zong-Hai Shi, Jun Zhong, Jian-Guo Liu, and Jun-Qing Li Copyright © 2016 Shi-Jie Gao et al. All rights reserved. Simultaneous Determination of Catalpol, Aucubin, and Geniposidic Acid in Different Developmental Stages of Rehmannia glutinosa Leaves by High Performance Liquid Chromatography Sun, 26 Jun 2016 12:12:15 +0000 Although R. glutinosa roots are currently the only organ source in clinics, its leaves are a potential supplement for the roots especially in extraction of some important bioactive compounds. Our early work found that the contents of catalpol and total iridoid glycosides varied among different developmental stages of R. glutinosa leaves. Aucubin and geniposidic acid, the abundant major bioactive compounds in Eucommia ulmoides and Gardenia jasminoides, respectively, were found present in R. glutinosa roots, however, and have not been analyzed in its leaves. In this paper, we aimed to determine contents of these three iridoid glycosides in different developmental stages of R. glutinosa leaves using the optimized HPLC-UV conditions. Our results showed that aucubin and GPA in R. glutinosa leaves were much lower than catalpol and showed the increasing trend with the leaf development, which was different from catalpol. This work provided the important information for future exploitation of R. glutinosa leaves as a potential supplement for its roots in extraction of some important bioactive compounds and studying the relationship of aucubin and catalpol metabolism. Yanjie Wang, Dengqun Liao, Minjian Qin, and Xian’en Li Copyright © 2016 Yanjie Wang et al. All rights reserved.