bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Thin-Layer Chromatographic Method for the Separation of Cholesterol, Egg Phosphatidylcholine, and Their Degradation Products
Authors: Gabriëls Margriet , Camu Frederik , Plaizier-Vercammen Jacqueline 
Published: February 2020

Abstract
Degradation products of egg phosphatidylcholine (EPC) and cholesterol were analyzed with different normal- and reversed-phase thin-layer chromatography (TLC) systems. The best separation, in terms of the highest number of degradation products from both analytes, was obtained with a reversed-phase system, using butanol–methanol–water–96–98% (v/v) acetic acid (40 + 40 + 20 + 4, v/v/v/v) as the mobile phase after overnight saturation at 25°C. A special development technique was used. After a first development, the plate was dried and a second development was performed in the same direction. This method enabled us to separate lysophosphatidylcholine, several free fatty acids and hydroperoxides, and several undefined degradation products of EPC and cholesterol. All products were visualized after the plate was dipped in a 1% (v/v) solution of 4-methoxybenzaldehyde in 98% sulfuric acid–96–98% (v/v) acetic acid–ethanol– water (2 + 10 + 60 + 30), presenting a blue color or a white spot against a colored background. After activation at 110°C, a stable color for both analytes was reached after 12 min. Precision of &lt;5% was obtained at 2 levels of analysis. Good linearity was obtained in the range of 5–30 μg for EPC (r = 0.991) and 5–40 μg for cholesterol (r = 0.991). These results show that TLC can be an inexpensive and easy alternative for the analysis of EPC and cholesterol.
Immunoaffinity Column as Sample Cleanup Method for Determination of the Beta-Adrenergic Agonist Ractopamine and Its Metabolites
Authors: Shelver Weilin L , Smith David J 
Published: February 2020

Abstract
A monoclonal antibody-based immunoaffinity column (RAC-IAC) was developed as a cleanup method for the determination of ractopamine and ractopamine glucuronides. [14C]Ractopamine (5 μg) and [14C]ractopamine glucuronides (5 μg) were fortified into 10 mL cattle urine, and loaded onto an RAC-IAC (5 mg IgG/mL) column. The column was washed and the bound analytes were eluted. In the initial loading and washing, 22% of the radioactivity was washed off and the subsequent elution step recovered 78%. A blank column prepared from nonspecific IgG retained &lt;10% of the radioactivity. The RAC-IACs were damaged by high methanol concentrations, preventing reuse. Elution of the analytes with 50mM glycine buffer, pH 2.8, prevented damage, and the columns could be reused at least 20 times with no change in performance. They were stored &gt;3 months in phosphate- buffered saline with 0.02% sodium azide at 4°C. The method was used with fortified cattle muscle, liver, and kidney samples with recoveries of 82.1 ± 7.6, 87.8 ± 1.9, and 92.5 ± 0.4%, respectively (n = 3). Similar studies with sheep muscle, liver, and kidney samples gave recoveries of 91.8 ± 0.2, 91.7 ± 0.3, and 92.3 ± 0.3, respectively ( n = 3). Liver and kidney samples were diluted to prevent column plugging, but all of the eluants were suitable for liquid chromatography analysis. This IAC is a selective, efficient, and economical cleanup method in a variety of matrixes for ractopamine determination.
Interlaboratory Comparison of Pesticide Recovery from Water Using Solid-Phase Extraction Disks and Gas Chromatography
Authors: Mersie Wondi , Clegg Chris , Wauchope R Don , Dumas Jose A , Leidy Ross B , Riley Melissa B , Young Roddy W , Mattice John D , Mueller Thomas C , Senseman Scott A 
Published: February 2020

Abstract
An interlaboratory study was conducted to assess the suitability of C18 solid-phase extraction disks to retain and ship different pesticides from water samples. Surface and deionized water samples were fortified with various pesticides and extracted using C18 disks. Pesticides were eluted from disks and analyzed in-house, or disks were sent to another laboratory where they were eluted and analyzed. Along with the disks, a standard pesticide solution in methanol was also shipped to be used for fortification, extraction, and analysis. The highest recovery from deionized or surface water using shipped disks was obtained for cyanazine (&gt;97%), followed by metalaxyl (&gt;96%), and atrazine (&gt;92%). Although &lt;40% of the bifenthrin, chlorpyrifos, and chlorothalonil fortified in surface water was recovered from shipped disks, recoveries from deionized water were &gt;70%. From in-house eluted disks, bifenthrin and chlorpyrifos were recovered at 118 and 105%, whereas chlorothalonil showed 71% recovery, indicating that poor recovery from surface water was due to loss during shipping rather than low retention by the C18 disks. There was no consistent relationship between recovery from C18 disk and physicochemical properties for the pesticides included in this study. For most of the 13 pesticides tested, there were no differences in recovery between in-house extracted disks and shipped disks, indicating the suitability of disks to concentrate and transport pesticides extracted from water samples.
Determination of St. John's Wort Components in Dietary Supplements and Functional Foods by Liquid Chromatography
Authors: Ang Catharina Y W , Cui Yanyan , Chang Hebron C , Luo Wenhong , Heinze Thomas M , Lin Lawrence J , Mattia Antonia 
Published: February 2020

Abstract
St. John's wort ( Hypericum perforatum L.) preparations, a top-selling botanical dietary supplement used primarily as an antidepressant, has recently been used as an ingredient in some food products sold as functional foods. A rapid extraction technique followed by a liquid chromatographic (LC) method was developed to determine 4 characteristic bioactive compounds (pseudohypericin, hypericin, hyperforin, and adhyperforin) from St. John's wort in dietary supplements and functional foods to which it was added. Solid samples, including including dried leaf/flower mixture, dietary supplement capsules, tea bags, puff and snack bar, were extracted with methanol by sonication.Noncarbonated, fruit-flavored drinks were centrifuged and mixed with methanol. Compounds were then determined by isocratic, reversed-phase LC with UV detection at 2 wavelengths and further identified or confirmed by photodiode array spectra and LC/mass spectrometry. Within-laboratory method variations (% RSD) were satisfactory. Very low amounts, if any, of the 4 components were found in drink and puff samples, and none was found in the snack bar. The methods developed provide a useful means for the determination of St. John's wort components in dietary supplements and functional foods.
Stability of Sulfonamides, Nitrofurans, and Chloramphenicol Residues in Preserved Raw Milk Samples Measured by Liquid Chromatography
Authors: Noa Mario , Perez Norma , Gutierrez Rey , Escobar Irma , Diaz Gilberto , Vega Salvador , Prado Guadalupe , Urban Georgina 
Published: February 2020

Abstract
A stability study was made of 10 antimicrobials: 6 sulfonamides, 3 nitrofurans, and chloramphenicol residues in raw milk samples preserved with 0.1% potassium dichromate (K2Cr2O7) and 0.05% mercuric bichloride (HgCl2) during cold storage for 7 days. Preserved milk samples fortified with 50 ppb of each antimicrobial were analyzed by liquid chromatography (modified AOAC Method 993.32). Drugs were extracted with chloroform–acetone after solvent evaporation residues were dissolved with aqueous sodium acetate buffer solution (0.02M, pH 4.8), and fat was removed with hexane. Sulfonamides and chloramphenicol were detected at 275 nm (UV) by using a gradient system of sodium acetate buffer solution–acetonitrile starting at 95 + 5 (v/v) and finishing at 80 + 20 (v/v). Nitrofurans were detected at 375 nm (UV) isocratically with sodium acetate buffer solution–acetonitrile (80 + 20, v/v). Residues stability was measured through recovery data. Sulfamethoxazole, sulfachloropyridazine, nitrofurazone, furazolidone, and furaltadone residues remained stable in the presence of either preservative for 7 days. Sulfamethazine and chloramphenicol were not affected by K2Cr2O7, but had significant losses ( p &lt;0.05) when HgCl2 was used: 26.2 and 13.4%, respectively. Average recoveries of sulfamonomethoxine, sulfamerazine, and sulfathiazole significantly decreased by Day 7, with losses of 17.1, 17.2, and 23.2% for K2Cr2O7, and 23.3, 20.7, and 48.0% for HgCl2, respectively. During 5 days of cold storage all antimicrobials tested, except sulfathiazole, remained stable in milk samples preserved with 0.1% K2Cr2O7 or 0.05% HgCl2.
Determination of Active Ingredient in Synthetic Pyrethroid Formulations by High-Performance Thin-Layer Chromatography/Densitometry
Authors: Sharma Krishan K 
Published: February 2020

Abstract
A new, simple, precise, and rapid high-performance thin-layer chromatography (HPTLC) method was developed for the analysis of commercial emulsifiable concentrate (EC) formulations of cypermethrin, α-cypermethrin, and λ-cyhalothrin. A known amount of reference grade synthetic pyrethroid and its EC formulation was subjected to TLC, and the amount of pesticide present in the active ingredient spot was estimated by densitometry in a single beam, single wavelength reflectance mode. Calibration curves of the synthetic pyrethroid was linear in the range of 8–24 μg, and the correlation coefficient for the calibration equation ranged between 0.97 and 0.99. Recoveries from laboratory-prepared test samples of the EC formulation were in the range of 95–99%. Pesticide formulations were further analyzed by gas liquid chromatography using flame ionization detector, and results were comparable. The proposed HPTLC method has application for quality control and determination of the shelf life of EC formulations.
Rapid Determination of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Water Samples by Using Solid-Phase Microextraction Followed by Gas Chromatography with Tandem Mass Spectrometry
Authors: Landín Pedro , Llompart María , Lourido Mercedes , García-Jares Carmen , Carro Nieves , Cela Rafael 
Published: February 2020

Abstract
A rapid and simple method of using solid-phase microextraction was developed for determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in water samples. In this method, the target analyte is extracted from the sample into the polymeric coating of the fused-silica fiber. After exposure, the fiber is thermally desorbed in the heated injection port of the gas chromatograph, and a chromatographic analysis is performed by using low-resolution tandem mass spectrometry. Parameters that may affect the extension of the microextraction process, such as sampling mode, sample volume, temperature, agitation, and sampling time, were studied. Extraction efficiencies for 3 coating fibers were investigated: 100 μm poly(dimethylsiloxane) (PDMS), 65 μm PDMS-divinylbenzene, and 75 μm carboxen-PDMS. Linearity was evaluated (R = 0.999) for a 250-fold concentration range from the fg/mL to the pg/mL level. The 2,3,7,8-TCDD was detected at the fg/mL level when the headspace over the water sample was sampled for 60 min; the limit of detection obtained was better than that of Method 8280B of the U.S. Environmental Protection Agency. The proposed method performed well when applied to the analysis of tap water, lake water, and seawater samples.
Determination of Deoxynivalenol and Nivalenol in Corn and Wheat by Liquid Chromatography with Electrospray Mass Spectrometry
Authors: Plattner Ronald D , Maragos Chris M 
Published: February 2020

Abstract
The fungus Fusarium graminearum is a pathogen of both wheat and corn. Strains of the fungus from the United States produce a toxin, deoxynivalenol (DON); strains of the fungus from Asia and Europe produce DON or a related toxin, nivalenol. These toxins can cause disease in livestock, and their potential presence in feed and foods is a concern for animal and human health. A method was developed to detect both toxins in corn and wheat by liquid chromatography/mass spectrometry of an extract of ground grain. The method requires no sample cleanup and can detect the toxins at 0.05 μg/g.
Analytical Pervaporation: A Key Technique in the Enological Laboratory
Authors: Luque de Castro Maria D , Luque-García Jose L , Mataix Eva 
Published: February 2020

Abstract
This paper reviews the use of analytical pervaporation (defined as the integration of 2 different analytical separation principles, evaporation and gas diffusion, in a single micromodule) coupled to flow-injection manifolds for the determination of analytes of interest in enology; the review discusses the advantages that these techniques can provide in wine analytical laboratories. Special attention is given to methods that enable the determination of either of 2 volatile analytes, or of one volatile analyte and one nonvolatile analyte by taking advantage of the versatility of the designed approaches. In a comparison of these methods with the official and/or standard methods, the results showed good agreement. In addition, the new methods offer improvements in linear determination range, quantitation limit, precision, rapidity, and potential for full automation. Thus, this review demonstrates that although the old technologies used in wine analytical laboratories may be supported by official and standard methods, they should be replaced by properly validated, new, and automated technologies.
Determination of Nitroimidazoles and Their Metabolites in Swine Tissues by Liquid Chromatography
Authors: Shen Jianzhong , Yhang Yue , Zhang Suxia , Ding Shuangyang , Xiang Xinhua 
Published: February 2020

Abstract
A liquid chromatographic method was developed for determination of metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), and 2-hydroxymethyl-1-methyl-5-nitroimidazole (DMZOH) in swine tissue. After extraction with ethyl acetate and evaporation, the nitroimidazoles were redissolved in hydrochloric acid. Hexane was used in the liquid–liquid extraction to remove fat. An Oasis® HLB solid-phase extraction was performed after neutralization of the acidic extract. The limits of detection were 1.0–2.0 μg/kg for DMZOH, MNZ, RNZ, and DMZ in muscle and liver. Average recoveries ranged from 80.1 to 83.9% in muscle fortified at 10, 20, and 50 μg/kg; average re-coveries in liver ranged from 78.9 to 82.3%. The procedure provides a simple and sensitive method for monitoring DMZOH, MNZ, RNZ, and DMZ residues in swine tissues.
Simultaneous Determination of Residues of Chloramphenicol, Thiamphenicol, Florfenicol, and Florfenicol Amine in Farmed Aquatic Species by Liquid Chromatography/Mass Spectrometry
Authors: van de Riet Jeffery M , Potter Ross A , Christie-Fougere Melissa , Burns B Garth 
Published: February 2020

Abstract
A liquid chromatographic (LC)/mass spectrometric (MS) method was developed for determining the residues of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in a number of aquatic species. The phenicols are extracted with acetone, the extracts are partitioned with dichloromethane, the aqueous layer is removed, and the organic layer is evaporated to dryness. The residue is dissolved in dilute acid and defatted with hexane, and the aqueous layer is prepared for analysis by LC. The phenicols are determined by reversed-phase LC by using a Hypersil C18-BD column with a water–acetonitrile gradient and MS detection using selectedion recording. Calibration curves were linear for all analytes between 0.015 and 0.425 ng injected. The relative standard deviations for measurements by the proposed method were &lt;10% for all of the analytes studied, with re-coveries ranging from 71% for florfenicol amine to 107% for florfenicol in salmon tissue spiked at the 2 ng/g level. Detection limits of 0.1 ng/g for florfenicol and chloramphenicol, 0.3 ng/g for thiamphenicol, and 1.0 ng/g for florfenicol amine are easily obtainable. The operational errors, interferences, and recoveries for spiked samples compare favorably with those obtained by established LC methodology. The proposed method is simple, rapid, and specific for monitoring residues of chloramphenicol, thiamphenicol, florfenicol, and florfenicol amine in a number of aquatic species.
Detection of Paralytic Shellfish Poison by Rapid Cell Bioassay: Antagonism of Voltage-Gated Sodium Channel Active Toxins in vitro
Authors: Manger Ronald L , Leja Linda S , Lee Sue Y , Hungerford James M , Kirkpatrick Mary Ann , Yasumoto Takeshi , Wekell Marleen M 
Published: February 2020

Abstract
Although cytotoxicity assays provide several advantages over mouse bioassays, sodium channel-blocking marine toxins, such as those associated with paralytic shellfish poison (PSP), require prolonged incubation periods of 24–48 h. This is in marked contrast to in vitro detection of sodium channel-enhancing marine toxins such as ciguatoxins or brevetoxins which can be accomplished in as few as 4–6 h. We developed a modified PSP cell bioassay that is as rapid as in vitro methods for sodium channel-enhancing toxins. The cell bioassay is based on a saxitoxin-dependent antagonism of the rapid in vitro effects of brevetoxin or ciguatoxin. Comparative analysis of naturally incurred PSP residues by both antagonism cell bioassay and the mouse bioassay demonstrated significant correlation. The simplicity, sensitivity, and enhanced kinetics of the new antagonism cell bioassay format provide the basis for development of a practical alternative to conventional mouse testing for PSP.
Rapid Determination of Fosetyl-Aluminum Residues in Lettuce by Liquid Chromatography/Electrospray Tandem Mass Spectrometry
Authors: Hernández Félix , Sancho Juan V , Pozo Óscar J , Villaplana Carme , Ibáñez María , Grimalt Susana 
Published: February 2020

Abstract
This paper describes a new method for the sensitive and selective determination of fosetyl-aluminum (Al) residues in vegetable samples. The method involves extraction with water by using a high-speed blender and subsequent injection of the 5-fold diluted extract into the liquid chromatograph. Fosetyl-Al is determined by liquid chromatography with electrospray tandem mass spectrometry after the addition of tetrabutylammonium acetate as the ion-pairing re-agent. The method has been used to assay lettuce samples spiked at 2 and 0.2 mg/kg. Recoveries were satisfactory, with mean values of 98 and 106%, respectively, and relative standard deviations were &lt;10%. The limit of quantitation was 0.2 mg/kg, and the limit of detection was as low as 0.05 mg/kg. Matrix-matched calibration was used for quantitation, and the addition of an internal standard improved repeatability. The developed method allows the accurate and rapid determination of low levels of fosetyl-Al residues in lettuce with very little sample handling and good sensitivity; it was shown to be robust by the analysis of almost 100 samples.
Improved Liquid Chromatographic Method for Determination of Organic Acids in Leaves, Pulp, Fruits, and Rinds of Garcinia
Authors: Jayaprakasha Guddadarangavvanahally K , Jena Bhabani S , Sakariah Kunnumpurath K 
Published: February 2020

Abstract
An improved liquid chromatographic (LC) method was developed for determination of organic acids in leaves, pulp, fruits, and rinds of Garcinia. At present, the commonly used LC method for analysis of organic acids in Garcinia extracts uses direct application of the extracts on the column. This practice gradually reduces efficiency of the column and shortens its life. In the improved method, the interfering substances such as pigments and xanthones were effectively removed by passing the aqueous extract through an ODS cartridge. With subsequent injection on a C18 reversed-phase column, using 6.0mM phosphoric acid as the mobile phase with a flow rate of 1.0 mL/min and UV detection at 210 nm, the organic acids were determined in the extracts. The major organic acid was (–)-hydroxycitric acid at the level of 2.5, 0.8, 3.0, and 20.1% in leaf, pulp, fresh fruit, and dried rinds, respectively. Minor quantities of hydroxycitric acid lactone, oxalic acid, and citric acid were also identified. Limits of detection and recoveries were 0.9–1.5 μg and 93.9–99.8%, respectively. This is the first report on the composition of organic acids from Garcinia pedunculata.
APLAC Interpretation and Guidance on the Estimation of Uncertainty of Measurement in Testing
Authors: Robertson Max , Chan Terence S S 
Published: February 2020

Abstract
The Asia Pacific Laboratory Accreditation Cooperation (APLAC) is the organization representing the community of bodies that accredit testing and calibration laboratories throughout the Asia Pacific region, including China and North America. APLAC members assess the competence of laboratories and grant them accreditation. They also provide mutual recognition of the equivalence of their accreditations, which facilitates international trade and acceptance by regulators. Harmonization of accreditation requirements is therefore vital to maintaining Mutual Recognition Arrangements. APLAC establishes management and technical criteria for accreditation and publishes guidance documents for accreditation bodies and laboratories.
Validation of Standardized High-Performance Thin-Layer Chromatographic Methods for Quality Control and Stability Testing of Herbals
Authors: Koll Kathrin , Reich Eike , Blatter Anne , Veit Markus 
Published: February 2020

Abstract
In herbal medicinal products the entire herbal drug or an herbal drug preparation is regarded as the active pharmaceutical ingredient, regardless of whether constituents with defined therapeutic activity are known. In quality control and stability testing of herbal medicinal products, fingerprint chromatograms are used as powerful tools to evaluate and compare the composition of compounds in such products. To fulfill the International Conference on Harmonization and Good Manufacturing Practice-based regulatory requirements in pharmaceutical quality control, chromatographic fingerprint analysis needs to be validated. Based on a standardized methodology, this paper provides a comprehensive concept for evaluating validation parameters for planar chromatographic fingerprinting by considering the stationary phase, sample application, developing solvent, chromatogram development, plate labeling, derivatization, documentation, and chromatographic equipment. Validation parameters addressed include stability of the analyte, selectivity, robustness testing, and method reproducibility.