bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiresidue Method for the Determination of Organophosphorus Pesticides in Cereal Matrixes
Authors: Mariani Maurizio Boccacci , D'aiuto Virginia , Giannetti Vanessa
Published: February 2020

Our research was focused on a preliminary comparison of three cleanup procedures for the determination of 26 organophosphorus (OP) pesticide residues in cereal matrixes. The aim of the study was to reduce the analytical problems associated with the presence of high-molecular-weight compounds in these matrixes in order to improve the efficiency of the chromatographic separation. The method was based on the extraction of OP pesticides from the samples with the use of petroleum ether, acetone, and dichloromethane, and on three different cleanup procedures, followed by GC identification. The first procedure was carried out with a multicartridge system; the second procedure consisted of a low-temperature lipid precipitation; for the third procedure, acid and neutral alumina were used for cleanup of the extract. The use of deactivated acidic alumina as the adsorbent medium and the use of n-hexanedichloromethaneethyl acetate (6 + 3 + 1, v/v/v) as the eluting system were preferred. After purification, the residue was injected into a gas chromatograph for separation followed by nitrogen-phosphorus detection; the identities of the OP pesticides in positive samples were confirmed by GC/MS. The proposed method could be extended to the determination of other OP pesticides in various food matrixes in routine analysis.
Simple and Rapid RP-HPLC Method for Simultaneous Determination of Acyclovir and Zidovudine in Human Plasma
Authors: Sharma Megha , Nautiyal Pragya , Jain Surendra , Jain Deepti
Published: February 2020

Combination therapy with acyclovir and zidovudine is used for the treatment of herpes-infected immunocompromised patients. In the view of the optimal drug concentrations (minimum effective concentrations) for viral suppression and avoidance of drug toxicity, monitoring of drug levels has been considered essential to determine drug concentrations in plasma after administration of a dose of acyclovir and zidovudine. A simple, precise, and rapid RP-HPLC method has been developed for this purpose. Chromatographic separation was performed using methanolwater (50 + 50, v/v), pH 2.5 adjusted with orthophosphoric acid, as an isocratic mobile phase at a flow rate of 0.8 mL/min with an Inertsil ODS (C18) column (5 µm particle size, 250 ⨯ 4.60 mm id). Detection was carried out using a UV photo diode array detector at 258 nm. The plasma samples were prepared by a protein precipitation method. The retention time for acyclovir and zidovudine was 3.5 ± 0.2 and 6.2 ± 0.3 min, respectively. The method was linear in the range of 2001800 and 4003600 ng/mL with LOQ of 200 ng (SD = ±1.4) and 400 ng (SD = ±0.9) for zidovudine and acyclovir, respectively, in plasma. The mean accuracy was 98.0 and 96.4, with average extraction recovery of 64.8 ± 2.1 and 77.5 ± 1.7 for lower nominal concentrations of acyclovir and zidovudine, respectively.
Single-Laboratory Validation of a Refined AOAC HPLC Method 2005.06 for Oysters, Cockles, and Clams in UK Shellfish
Authors: Turner Andrew D , Hatfield Robert G , Rapkova-Dhanji Monika , Norton Deirdre M , Algoet Myriam , Lees David N
Published: February 2020

In 2009, a refined HPLC method based on AOAC Official MethodSM 2005.06 was developed and validated for the determination of paralytic shellfish poisoning (PSP) in mussels. A single-laboratory validation study of this method was undertaken here for the analysis of PSP toxins in oysters, cockles, clams, and razor clams. The method was characterized for selectivity, sensitivity, linearity, precision, repeatability, recovery, ruggedness, and uncertainty of measurement. Validation data were utilized to determine method performance characteristics for non-mussel bivalves for all commercially available certified reference toxins, extending the method to dcNEO and dcGTX2,3, where available. A period of parallel testing of oysters, cockles, and clams enabled a comparison of sample toxicities obtained using mouse bioassay (MBA) and HPLC methodologies, although only a very low number of PSP-positive samples were obtained through the United Kingdom official control monitoring program. Results from the MBA and HPLC methods were well-correlated for PSP-negative samples, but the low number of naturally contaminated PSP-positive samples has prevented any comparative statistical assessment of method performance for non-mussels between the two official methods. However, some evidence for potentially significant differences in total saxitoxin equivalents obtained by the two methods in some species has highlighted the need for further comparative testing in non-mussel samples to be conducted prior to implementation of the HPLC method in routine official control monitoring programs.
Simultaneous Determination of Eight Synthetic Permitted and Five Commonly Encountered Nonpermitted Food Colors in Various Food Matrixes by High-Performance Liquid Chromatography
Authors: Dixit Sumita , Khanna Subhash K , Das Mukul
Published: February 2020

A simple and sensitive HPLC method has been developed for the simultaneous determination of eight permitted food colors and five commonly encountered nonpermitted colors in various food commodities, including sugar-, fat-, and starch-based food matrixes. The method uses a specific food category-based cleanup/treatment procedure before color extraction to avoid the interference of food matrixes, and to obtain the optimal color extraction. Analysis was performed on a reversed-phase C18 -Bondapak column with ammonium acetate and acetonitrile gradient elution as the mobile phase; a programmable max-specific visible detection was used to monitor colors to obtain the higher sensitivity and expanded scope needed for multicolor blends having diverse absorption maxima. All colors showed good linearity, with regression coefficients of 0.99740.9999. The LOD and LOQ values ranged from 0.01 to 0.12 mg/L, and from 0.04 to 0.83 mg/L or mg/kg, respectively. The intraday and interday precision tests produced good RSD values, and the recoveries from different food matrixes ranged from 82 to 104%. The method offers high sensitivity for analysis of a wide variety of food matrixes containing a broad scope of multicolor blends. Two nonpermitted colors, orange II and metanil yellow, were found. Also, a number of samples contained permitted colors at levels two-to seven-fold higher than those prescribed.
New Anion-Exchange Solid-Phase Extraction Support Used for Preconcentration and Determination of Lead in Water Samples by Flame Atomic Absorption Spectrometry
Authors: Panahi Homayon Ahmad , Feizbakhsh Ali Reza , Tafazoli Zahra , Moniri Elham , Nezhati Mahshid Nikpour , Moghaddam Hamid Hashemi , Kelahrodi Somayeh Rangbar
Published: February 2020

A new chelating resin was prepared by coupling Amberlite XAD-2 with Brilliant Green through an azo spacer. The resulting resin has been characterized by FTIR spectrometry, elemental analysis, and thermogravimetric analysis and studied for the preconcentration and determination of trace Pb(II) ions from solution samples. The anionic complex of Pb(II) and iodide was retained on the resin by the formation of an ion associate with Brilliant Green on Amberlite XAD-2 in weak acidic medium. The optimum pH value for sorption of the metal ion was 5.5. The sorption capacity of the functionalized resin is 53.8 mg/g. The chelating resin can be reused for 20 cycles of sorptiondesorption without any significant change in sorption capacity. A recovery of 103% was obtained for the metal ion with 0.1 M EDTA as the eluting agent. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The resin was subjected to evaluation through batch binding and column chromatography of Pb(II). The equilibrium adsorption data of Pb(II) on modified resin were analyzed by Langmuir, Freundlich, and Temkin models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined to be 0.192, 13.189, and 3.418 at pH 5.5 and 25C. The method was applied for lead ion determination in tap water samples.
Separation of Four Mixtures of Pesticides by Pressurized Planar Electrochromatography (PPEC)
Authors: Tuzimski Tomasz
Published: February 2020

Examples of separations of four mixtures of pesticides by pressurized planar electrochromatography (PPEC) under different operating conditions are presented. The samples were separated on a prewetted RP-18W chromatographic plate in a system with acetonitrilebuffer as the mobile phase. A potential of 2.3 kV was applied to a 10 cm long plate to create the electric field. Reproducible retention of pesticides was obtained during PPEC in the closed system when the sorbent layer of the plate was prewetted and equilibrated with the mobile phase. The reported separations of pesticides by PPEC are over 10 times faster than the corresponding separations by TLC.
LC/MS/MS Study for Identification of Entacapone Degradation Product Obtained by Photodegradation Kinetics
Authors: Paim Clés S , Palma Eduardo C , Malesuik Marcelo D , Steppe Martin
Published: February 2020

Entacapone is indicated for clinical use as an adjunct to levodopa/carbidopa to treat patients with idiopathic Parkinson's Disease who experience the signs and symptoms of end-of-dose wearing-off. The aim of this study was to determine the photodegradation kinetics and to elucidate the structure of the main degradation product. The stability of entacapone was studied in order to investigate the degradation kinetics of this drug using LC as a stability indicator. Entacapone was subjected to accelerated photodegradation. This study was carried out with methanolic solutions, prepared from coated tablets, in quartz cells under UV light at 254 nm. The degradation process of entacapone in solutions can be described by second-order kinetics under the experimental conditions used in this study. The LC/MS/MS determinations revealed that in the above conditions the photodegraded product formed the geometric isomer of entacapone (Z-entacapone). The obtained results show the importance of appropriate light protection during the drug development process, storage, and handling.
Classification of Wines from Five Spanish Origin Denominations by Aromatic Compound Analysis
Authors: Sáenz Cecilia , Cedráenzn Trinidad , Cabredo Susana
Published: February 2020

Wine is a complex matrix in which aroma compounds play an important role in the characterization of the flavor pattern of a given wine. Twelve volatile compounds were determined in 244 samples of Spanish red wines from different denominations of origin: Rioja, Navarra, Valdepeas, La Mancha, and Cariena. The samples were analyzed by GC using headspace solid-phase microextraction. The concentration (mg/mL) intervals obtained were 3-methyl-butyl acetate (3.9 to 116), 3-methyl-1-butanol (93 to 724), ethyl hexanoate (0.8 to 39), 1-hexanol (0.3 to 6.7), ethyl octanoate (1.4 to 41), diethyl succinate (0.2 to 13), 2-phenyl ethyl acetate (0 to 5.3), hexanoic acid (0 to 8.3), geraniol (0 to 3.0), 2-phenylethanol (1.5 to 56), octanoic acid (0 to 20), and decanoic acid (0 to 3.3). Wines were classified by multivariate statistical methods: principal component analysis, and lineal discriminant analysis. A correct differentiation among wines according to their origin was obtained by lineal discriminant analysis.
Theoretical and Experimental Aspects of Microbicidal Activities of Hard Surface Disinfectants: Are Their Label Claims Based on Testing Under Field Conditions?
Authors: Omidbakhsh Navid
Published: February 2020

High-touch environmental surfaces are important in the spread of many nosocomial pathogens. Although such surfaces are routinely disinfected, the testing and label claims of many common disinfectants do not reflect the realities of field use. A study was conducted to determine the influence of several crucial factors on the action of disinfectants in general, and to assess the killing efficiency of selected chemistries against Staphylococcus aureus and Pseudomonas aeruginosa, related to their drying times (i.e., after one application) and label-specified contact times using a quantitative carrier test. The products were also tested for their ability to wet a hydrophobic (epoxy resin) surface. The hard-surface disinfectants (in-use concentration in ppm) tested were: (a) chlorine bleach (500); (b) quaternary ammonium compounds (quat; 600) alone; (c) quat (3000) with 17 isopropanol (v/v); (d) quat (3000) with 60 ethanol (v/v); (e) phenolic (800) alone; (f) quat (2000), phenolic (3000) with 70 ethanol (v/v); and (g) accelerated hydrogen peroxide (AHP; 5000 of H2O2). The arbitrarily set criterion of bactericidal activity was 6 log10 reduction in the viability of both species tested. All surfaces tested with all products dried in <5 min, with alcohol-based surfaces drying significantly faster. Even though the alcohol-free quat and phenolic claim a contact time of 10 min, they dried in <4 min after a single application and failed to meet the performance criterion. Bleach (500 ppm) dried in about 3 min and was effective. AHP also dried in about 3 min and met its label claim even at 1 min of contact. Quat (3000) with 17 isopropanol dried at 1 min and was effective. Quat (3000) with 60 ethanol and quat (2000), phenolic (3000) with 70 ethanol dried in <1 min, and were ineffective. AHP, alcohol-containing quats, and quat-phenolic-alcohol gave acceptable wettability, while quat and phenolic alone, as well as bleach, covered the treated surface unevenly. The findings show that label claims, especially those for contact times, fail to reflect the way many hard-surface disinfectants are used in the field.
Studies on Phytoestrogenic and Nonphytoestrogenic Compounds in Trifolium incarnatum L. and Other Clover Species Using Pressurized Liquid Extraction and High Performance Column Liquid Chromatography with Photodiode-Array and Fluorescence Detection
Authors: Zgórka Grażyna
Published: February 2020

HPLC coupled with photodiode array (PDA) and fluorescence (FL) detectors has been used for the identification and determination of phytoestrogenic (isoflavones and coumestrol) and nonphytoestrogenic (flavones) compounds in hydrolyzed and nonhydrolyzed extracts obtained from aerial parts of Trifolium incarnatum L. and related clover species. The effective isolation technique of pressurized liquid extraction (PLE) was used. Various types of extraction solvents, i.e., ethanol, n-propanol, n-butanol, and water solutions (75%, v/v) of methanol or ethanol at changeable or constant temperatures were tested, taking into account the chemical character of isolated compounds. Higher PLE efficiency in relation to isoflavone aglycones was found for ethanol. Predominant isoflavone glycosides determined in clover samples were sissotrin and ononin, reaching levels above 1.4% dry weight (wt) in T. medium. The presence of flavone compounds (apigenin and luteolin) in aerial parts of T. incarnatum, occurring in amounts exceeding 0.4% dry wt, documented chemotaxonomic distinction of this species from other clovers examined. Additionally, within the group of phytoestrogenic isoflavones, only biochanin A and formononetin derivatives were identified in above-ground parts of T. incarnatum . The application of simultaneous PDA and FL detection enabled unambiguous confirmation of the lack of a strong phytoestrogen, coumestrol, in all hydrolyzed and nonhydrolyzed clover extracts.
Simultaneous Determination of Some Components in Detergent Washing Powder by Mid-Infrared Spectrometry and Artificial Neural Network
Authors: Khanmohammadi Mohammadreza , Garmarudi Amir Bagheri , Rouchi Mohammad Babaei , Khoddami Nafiseh
Published: February 2020

A method has been established for simultaneous determination of sodium sulfate, sodium carbonate, and sodium tripolyphosphate in detergent washing powder samples based on attenuated total reflectance Fourier transform IR spectrometry in the mid-IR spectral region (800–1550 cm−1). Genetic algorithm (GA) wavelength selection followed by feed forward back-propagation artificial neural network (BP-ANN) was the chemometric approach. Root mean square error of prediction for BP-ANN and GA-BP-ANN was 0.0051 and 0.0048, respectively. The proposed method is simple, with no tedious pretreatment step, for simultaneous determination of the above-mentioned components in commercial washing powder samples.
Determination of Operating Characteristic, Retesting, and Testing Amount Probabilities Associated with Testing for the Presence of Salmonella in Foods
Authors: McClure Foster D , Lee Jung K
Published: February 2020

The relatively small perceived probability associated with retesting a food for the presence of Salmonella at low levels is often considered as one of the reasons that a confirmatory or check-analysis tends to disagree in practice with the results of an original test. Given a retesting process where a retest is only performed to confirm an original positive Salmonella test, the probability that both the original and retest will test positive for Salmonella has been traditionally determined by some as the product of the probabilities of a positive Salmonella test for the original and retest samples. When examining the probabilities associated with the retesting process, we found that our results disagreed with those based on intuitions apparently held by others concerning how these probabilities should be calculated. For Salmonella testing, operating characteristic values were computed to demonstrate the protections afforded by the Salmonella sampling plans presented in the U.S. Food and Drug Administration's Bacteriological Analytical Manual and to obtain the probability of a positive Salmonella test. The geometric distribution was examined for possible utility in determining the probabilities associated with testing amounts, i.e., the number of Salmonella tests needed to obtain a positive test.
Gas Chromatographic Determination of Bifenthrin in Technical and Selected Formulated Products: Collaborative Study
Authors: Kikta Edward J ,   Collaborators:, Bennett O O , Bradbury L , Coco P , Henley K , Hernandez A , Larson R , Lew C , Pandey S Y , Podhorniak L , Rains D , Ritland C , Nelson R , Wan P
Published: February 2020

A GC method for the analysis of technical and formulated bifenthrin samples was evaluated in a collaborative study. Bifenthrin is determined by using a 50 (trifluoropropyl)-methylpolysiloxane wide-bore capillary column and flame ionization detector. Ten samples, consisting of four formulations and a technical material were analyzed by 12 collaborators using Youden pairs. The four formulation types included in this study were microemulsion (ME), wettable powder (WP), suspension concentrate (SC), and emulsifiable concentrate (EC). Variability in the analysis of two of the formulation types, SC and EC, was later found to be due to the noncommercial containers used to hold the test samples. Because of this, valid data could not be obtained for the EC and SC. For the two formulations for which valid data could be obtained, ME and WP, and the technical chemical, accuracy and variability results are typical of large data sets. For the technical chemical and the two formulations for which valid data were obtained, Official First Action is recommended.
Determination of Anthocyanins in Cranberry Fruit and Cranberry Fruit Products by High-Performance Liquid Chromatography with Ultraviolet Detection: Single-Laboratory Validation
Authors: Brown Paula N , Shipley Paul R
Published: February 2020

A single-laboratory validation study was conducted on an HPLC method for the detection and quantification of cyanidin-3-O-galactoside (C3Ga), cyanidin-3-O-glucoside (C3Gl), cyanidin-3-O-arabinoside (C3Ar), peonidin-3-O-galactoside (P3Ga), and peonidin-3-O-arabinoside (P3Ar) in cranberry fruit (Vaccinium macrocarpon Aiton) raw material and finished products. An extraction procedure using a combination of sonication and shaking with acidified methanol was optimized for all five anthocyanins in freeze-dried cranberry fruit and finished products (commercial extract powder, juice, and juice cocktail). Final extract solutions were analyzed by HPLC using a C18 RP column. Calibration curves for all anthocyanin concentrations had correlation coefficients (r2) of 99.8. The method detection limits for C3Ga, C3Gl, C3Ar, P3Ga, and P3Ar were estimated to be 0.018, 0.016, 0.006, 0.013, and 0.011 g/mL, respectively. Separation was achieved with a chromatographic run time of 35 min using a binary mobile phase with gradient elution. Quantitative determination performed in triplicate on four test materials on each of 3 days (n 12) resulted in RSDr from 1.77 to 3.31. Analytical range, as defined by the calibration curves, was 0.5736.53 0000000g/mL for C3Ga, 0.159.83 g/mL for C3Gl, 0.2817.67 g/mL for C3Ar, 1.0164.71 g/mL for P3Ga, and 0.4227.14 g/mL for P3Ar. For solid materials prepared by the described method, this translates to 0.063.65 mg/g for C3Ga, 0.020.98 mg/g for C3Gl, 0.031.77 mg/g for C3Ar, 0.106.47 mg/g for P3Ga, and 0.042.71 mg/g for P3Ar.
Monitoring Disopyramide, Lidocaine, and Quinidine by Micellar Liquid Chromatography
Authors: Ochoa-Aranda Enrique , Esteve-Romero Josep , Rambla-Alegre Maria , Martinavarro-Domnguez Adri , Marcos-Toms Jos V , Bose Devasish
Published: February 2020

A micellar liquid chromatography (MLC) method using a C18 column was developed to determine three antiarrhythmic drugsdisopyramide, lidocaine, and quinidinethat are most usually monitored in serum samples. After the application of an interpretative strategy for optimization of sodium dodecyl sulfate (SDS) and modifier concentrations in order to ensure the minimum analysis time, maximum sensitivity, and good resolution, the optimum chromatographic conditions for the determination of the three antiarrhythmics were flow rate, 1 mL/min; injection volume, 20 L; separation temperature, 25C; mobile phase, 150 mmol/L SDS-7 (v/v) butanolphosphate buffer, 10 mmol/L, pH 70.9 (w/v) NaCl; and detection at 214 nm. The calibration curves for the drugs were linear (r2 > 0.999). The intraday and interday precisions were lower than 3.9 (CV). Recoveries were 100 0.6 when the method was applied to both serum samples spiked with the antiarrhythmics (n 10) and real serum samples. In all cases, the results were similar to those obtained using the reference method (fluorescence polarization immunoassay) usually used in the Spanish hospital. The proposed method is useful for hospital monitoring of the antiarrhythmics by direct injection into the chromatograph.
Validated Stability-Indicating HPLC Method for Paricalcitol in Pharmaceutical Dosage Form According to ICH Guidelines: Application to Stability Studies
Authors: Ortega Raquel , Navas Natalia , Salmerón Antonio , Cabeza José , Capitán-Vallvey Luís F
Published: February 2020

A stability-indicating HPLC method with diode array detection for the determination of paricalcitol, a synthetic vitamin D2 analog, was developed. Analytical parameters were studied according to International Conference on Harmonization guidelines. A C18 column (250 4.6 mm, 5 m particle size) maintained at 25C was used as the stationary phase, and acetonitrilewater (70 30, v/v) as the mobile phase. Chromatograms were recorded at 250 nm. In forced degradation studies, the effects of acid, base, oxidation, temperature, and UV light were investigated and showed no interference with the drug peak. The method was found to be linear (r 0.9989) at concentrations ranging from 0.6 to 10.0 mg/L paricalcitol, precise (repeatability and intermediate precision estimated as RSD less than 3.5), accurate (recoveries higher than 95), specific, and robust. The LOD and LOQ were 0.6 and 0.2 mg/L, respectively. The validated method was used for paricalcitol determination in a formal stability study of its pharmaceutical dosage form in preloaded syringes. The stability of a diluted solution of its pharmaceutical form in Viaflo bags was also tested. The results showed that paricalcitol was stable in preloaded syringes during a period of 30 days from preparation in the different storage conditions tested (room temperature without protection from daylight and 4.4C with protection from daylight). On the contrary, paricalcitol was quickly lost when stored in Viaflo bags by adsorption onto the walls of the container.
Determination of Pesticide Residues in Honey by Single-Drop Microextraction and Gas Chromatography
Authors: Tsiropoulos Nikolaos G , Amvrazi Elpiniki G
Published: February 2020

A novel, simple, and rapid single-drop microextraction (SDME) procedure combined with GC has been developed, validated, and applied for the determination of multiclass pesticide residues in honey samples. The SDME was optimized using a Plackett-Burman screening design considering all parameters that may influence an SDME procedure and a consequent central composite design to control the parameters that were found to significantly influence the pesticide determination. The developed analytical method required minimal volumes of organic solvents and exhibited good analytical characteristics with enrichment factors ranging from 3 for -endosulfan to 10 for lindane, procymidone, and captan and method quantification limits ranging from 0.03 g/kg for phosalone to 10.6 g/kg for diazinon. The relative recoveries obtained ranged from 70.8 for captan to 120 for fenarimol, and the precision (RSD) ranged from 3 to 15. The proposed SDME procedure followed by GC with an electron capture detector for quantification and GC/MS for identification was applied with success to the analysis of 17 honey samples. Monitoring results indicated a low level of honey contamination by diazinon, chlorpyrifosethyl, procymidone, bromopropylate, and endosulfan (-, -, and endosulfan sulfate) residues that were far below the maximum residue limit values specified by the European Union for endosulfan (10 g/kg) and bromopropylate (100 g/kg) in honey samples.
Determination of Lead and Manganese in Biological Samples and Sediment Using Slurry Sampling and Flame Atomic Absorption Spectrometry
Authors: Vieira Daniel Rodrigues , Castro Jacira Teixeira , Lemos Valfredo Azevedo
Published: February 2020

A procedure was developed for the determination of lead (Pb) and manganese (Mn) using slurry sampling. The two elements were detected using flame atomic absorption spectrometry with a slotted tube atom trap. Slurries were prepared by adding nitric acid solution (0.30, w/v) to a powdered sample (0.10 g). After homogenization by ultrasonic bath for 15 min, the slurries were introduced directly into the detection equipment. Some conditions of the procedure were evaluated, such as acid concentration, presence of surfactants, and sonication time. Under optimized conditions, the LODs and LOQs achieved were 0.8 and 2.6 g/g for Pb and 0.5 and 1.6 g/g for Mn, respectively. The precision obtained varied between 3.1 and 5.8 (Mn), and 2.6 and 5.4 (Pb) for slurries of shrimp and sediment. The analytical curves were established using aqueous standards in nitric acid solutions. The accuracy of the method was assessed through the determination of Pb and Mn in the following certified reference materials: ERM-CE 278 (mussel tissue), CRM 397 (human hair), and SRM 1646a (estuarine sediment). The proposed procedure was successfully applied to the determination of Pb and Mn in six samples of shrimp powder, seasoning, and river sediment. The levels of Mn detected varied from 2.2 to 71.3 g/g; Pb was detected in only one sediment sample (4.3 g/g).
Study and Development of Reversed-Phase HPLC Systems for the Determination of 2-Imidazolines in the Presence of Preservatives in Pharmaceutical Preparations
Authors: Antoniou Constantinos G , Markopoulou Catherine K , Kouskoura Maria G , Koundourellis John E
Published: February 2020

Different HPLC chromatographic systems were investigated on a C18ACE 5 μm, 150 × 4.6 mm id column for the determination of tymazoline, tramazoline, and antazoline, with either naphazoline or xylometazoline, in commercial preparations. For the development and optimization of the systems, a Response Surface Method (r = 0.925–0.980) was used to illustrate the changes in k as a function of pH values and different salt concentrations. The simultaneous separation of 2-imidazolines was accomplished at 40°C with 0.01 M ammonium acetate–methanol (50 + 50, v/v, pH 6.0) mobile phase at a flow rate of 1.2 mL/min. In order to deal with the usual coexistence of 2-imidazolines with benzethonium and benzalkonium chloride preservatives, it was necessary to use another chromatographic system, 0.01 M ammonium acetate–methanol (50 + 50, v/v) mobile phase on a cyano ACE 5 μm, 150 × 4.6 mm id column. As part of a more thorough theoretical investigation, a partial least-squares (PLS) technique was used for modeling the RP-HPLC retention data. The model was based on molecular structure descriptors of the analytes' X variables and on their retention time (Log K) Y. The goodness of fit was estimated by the PLS correlation coefficient (r2) and root mean square error of estimation values, which were 0.994 and 0.0479, respectively.
Liquid Chromatographic Method for the Simultaneous Determination of Eprosartan and Hydrochlorothiazide in Tablets and Human Plasma
Authors: Belal Fathalla , El-Brashy Amina M , El-Enany Nahed , Tolba Manar M
Published: February 2020

A new, specific, and sensitive RP-HPLC method was developed for the simultaneous determination of eprosartan (EPR) and hydrochlorothiazide (HCT). Good chromatographic separation was achieved using a 250 × 4.6 mm id, 5 μm particle size Symmetry® C18 column. The mobile phase acetonitrile–0.1 M phosphate buffer (35 + 65, v/v), pH 4.5, was pumped at a flow rate of 1 mL/min, with UV detection at 275 nm. The method showed good linearity in the ranges of 0.5–50 and 0.1–10 μg/mL, with LOD of 0.06 and 0.02 μg/mL and LOQ of 0.20 and 0.08 μg/mL for EPR and HCT, respectively. The proposed method was successfully applied for the analysis of the studied drugs in their synthetic mixture and co-formulated tablets. The method was further extended to the in vitro and in vivo determination of the two drugs in spiked and real human plasma. Interference likely to be encountered from the co-administered drugs was studied.
DuPont Qualicon BAX® System Assay for Genus Listeria 24E
Authors: Wallace F Morgan , Fallon Dawn , DeMarco Daniel , Varkey Stephen
Published: February 2020

The new BAX® System PCR Assay for Genus Listeria 24E was evaluated for detecting Listeria spp. in frankfurters, spinach, cooked shrimp, queso fresco cheese, and on stainless steel surfaces with a single-stage enrichment in BAX System 24 Listeria Enrichment Broth (24 LEB). Method comparison studies performed on samples with low-level inoculates showed that the BAX System demonstrates a sensitivity equivalent or superior to the U.S. Food and Drug Administration's Bacteriological Analytical Manual and the U.S. Department of Agriculture-Food Safety and Inspection Service culture methods, but with a significantly shorter time to result. Tests to evaluate inclusivity and exclusivity returned no false-negative and no false-positive results on a diverse panel of isolates, and tests for lot-to-lot variability and tablet stability demonstrated consistent performance. Ruggedness studies determined that none of the factors examined, within the range of deviations from specified parameters examined, affect the performance of the assay.
Flame Atomic Absorption Determination of Trace Amounts of Cadmium After Preconcentration Using a Thiol-Containing Task-Specific Ionic Liquid
Authors: Mohamadi Maryam , Mostafavi Ali
Published: February 2020

Dispersive liquid–liquid microextraction (DLLME) based on a task-specific ionic liquid (TSIL) was developed for the extraction and preconcentration of trace amounts of cadmium from aqueous samples, followed by flame atomic absorption spectrometry (FAAS) determination. In the proposed approach, cadmium ions are extracted from aqueous samples using small volumes of trioctylmethylammonium thiosalicylate (TOMATS) dissolved in acetone. TOMATS is a thiol-containing TSIL that can form metal thiolate complexes due to the chelating effect of the ortho-positioned carboxylate group relative to the thiol functionality. The main parameters affecting the performance of DLLME based on TSIL, such as pH, amount of TOMATS, extraction time, injection volume, salt addition, and centrifugation time, were optimized. Under optimum conditions, an LOD of 1.16 ng/mL and a good RSD of 1.8% at 60.0 ng/mL were obtained (n = 7). The proposed method was applied to tap water, wastewater, well water, and milk samples. The results showed that DLLME based on TSIL combined with FAAS is a rapid, simple, sensitive, selective, low cost, volatile organic solvent-free, and efficient analytical method for the separation and determination of trace amounts of cadmium ions.
Development and Validation of an HPLC Method for Mefloquine Hydrochloride Determination in Tablet Dosage Form
Authors: Nogueira Fernando Henrique Andrade , Goulart Letícia De Paula Lana , César Isabela Da Costa , De Campos Lígia Maria Moreira , Pianetti Gérson Antônios
Published: February 2020

A simple HPLC method for determination of meﬂoquine hydrochloride in tablets was developed and validated. The separation was carried out on an Xterra RP18 (250 × 4.6 mm id, 5 µm particle size) analytical column. The mobile phase was 0.05 M monobasic potassium phosphate buffer (pH 3.5)–methanol (40 + 60, v/v). The ﬂow rate and wavelength were set to 1 mL/min and 283 nm, respectively. The method was specifc for meﬂoquine hydrochloride in the presence of hydrolytic, oxidative, and photolytic degradation products. It was also linear, precise, accurate, and robust, being suitable for routine QC analyses and stability studies. The developed HPLC method was compared to a previously described spectrophotometric method.
Evaluation of Applied Biosystems MicroSEQ® Real-Time PCR System for Detection of Salmonella spp. in Food
Authors: Balachandran Priya , Cao Yanxiang , Wong Lily , Furtado Manohar R , Petrauskene Olga V , Tebbs Robert S
Published: February 2020

Real-time PCR methods for detecting foodborne pathogens offer the advantages of simplicity and quick time-to-results compared to traditional culture methods. In this study, the MicroSEQ® real-time PCR system was evaluated for detection of Salmonella spp. in 10 different food matrixes following the AOAC Research Institute's Performance Tested MethodSM validation program. In addition, the performance of the MicroSEQ system was evaluated for the detection of Salmonella in peanut butter as a part of the Emergency Response Validation Program sponsored by the AOAC Research Institute. The system was compared to the ISO 6579 reference method using a paired-study design for detecting Salmonella spp. in raw ground beef, raw chicken, raw shrimp, Brie cheese, shell eggs, cantaloupe, chocolate, black pepper, dry infant formula, and dry pet food. For the peanut butter study, the system was compared to the U.S. Food and Drug Administration's Bacteriological Analytical Manual procedures using an unpaired-study design. No significant difference in performance was observed between the MicroSEQ Salmonella spp. detection system and the corresponding reference methods for all 11 food matrixes. The MicroSEQ system detected all Salmonella strains tested, while showing good discrimination against detection of an exclusivity panel of 30 strains, with high accuracy.
DuPont Qualicon BAX® System Real-Time PCR Assay for Escherichia coli O157:H7
Authors: Burns Frank , Fleck Lois , Andaloro Bridget , Davis Eugene , Rohrbeck Jeff , Tice George , Wallace Morgan
Published: February 2020

Evaluations were conducted to test the performance of the BAX® System Real-Time PCR assay, which was certified as Performance Tested MethodSM 031002 for screening E. coli O157:H7 in ground beef, beef trim, spinach, and lettuce. Method comparison studies performed on samples with low-level inoculates showed that the BAX System demonstrates a sensitivity equivalent or superior to the FDA-BAM and the USDA-FSIS culture methods, but with a significantly shorter time to result. Tests to evaluate inclusivity and exclusivity returned no false-negative and no false-positive results on a diverse panel of isolates, and tests for lot-to-lot variability and tablet stability demonstrated consistent performance. Ruggedness studies determined that none of the factors examined affect the performance of the assay. An accelerated shelf life study determined an initial 36 month shelf life for the test kit.
Development and Validation of an HPLC Stability-Indicating Method for Identification and Assay of Elemental Iron(II) in Pharmaceutical Drug Products Using Reversed-Phase HPLC
Authors: Dias Neil C , Rustum Abu M
Published: February 2020

Ferrous sulfate tablets are a supplementary iron source for people who suffer from iron defciency anemia. A simple, fast, and QCfriendly HPLC method was developed and validated to determine elemental iron in ferrous sulfate drug products. A TSK-GEL Super octadecylsilyl column (50 × 4.6 mm id, 2 µm particle size) with a mobile phase consisting of 0.06 M methanesulfonic acid in water–acetonitrile (40 + 60, v/v) and UV detection at 282 nm were used for this method. Separation of the elemental iron peak from the matrix was achieved within 5 min. This method was successfully validated according to International Conference on Harmonization guidelines, and shown to be stability-indicating for the shelf-life samples of ferrous sulfate tablets, as well as selective for the analyte of interest.
Uncertainty Component Evaluation in Conventional Microbiological Qualitative Measurements
Authors: Tak Ka Charlotte Chan
Published: February 2020

To couple method performance and QA in microbiological testing, uncertainty profles have been developed according to relevant LODs and their confdence intervals. Percentage probability of failure is proposed to express this uncertainty. Analysis variance is divided into four categories: uncertainty originating from the sample, uncertainty originating from variations in procedure, uncertainty originating from the measurement system, and uncertainty originating in repeatability/reproducibility.
Determination of Residual Fluoroquinolones in Honey by Liquid Chromatography Using Metal Chelate Affinity Chromatography
Authors: Yatsukawa Yoh-Ichi , Ito Hironobu , Matsuda Takahiro , Nakamura Munetomo , Watai Masatoshi , Fujita Kazuhiro
Published: February 2020

A new analytical method for the simultaneous determination of seven ﬂuoroquinolones, namely, norﬂoxacin, ciproﬂoxacin, danoﬂoxacin, enroﬂoxacin, orbiﬂoxacin, saraﬂoxacin, and diﬂoxacin, especially in dark-colored honey, has been developed. Fluoroquinolone antibiotics were extracted from samples with MacIlvaine buffer solution (pH 4.0) containing EDTA disodium salt dihydrate. The extracts were treated with both a polymeric cartridge and a metal chelate affnity column preloaded with ferric ion (Fe3+). LC separation with ﬂuorescence detection was performed at 40°C using an Inertsil ODS-4 analytical column (150 × 4.6 mm, 3 µm). The mobile phase was composed of 20 mM/L citrate buffer solution (pH 3.1)–acetonitrile mixture (70 + 30, v/v) containing 1 mM/L sodium dodecyl sulfate. Lomeﬂoxacin was used as an internal standard. The developed method was validated according to the criteria of European Commission Decision 2002/657/EC. Decision limits and detection capabilities were below 2.9 and 4.4 μg/kg, respectively.
Quantitative Determination of Pregnanes from Aerial Parts of Caralluma Species Using HPLC-UV and Identification by LC-ESI-TOF
Authors: Avula Bharathi , Shukla Yatin J , Wang Yan-Hong , Khan Ikhlas A
Published: February 2020

An HPLC method was developed for the quantitative determination of five pregnane derivatives from aerial parts of Caralluma species and dietary supplements. The method was validated for linearity, repeatability, LOD, and LOQ. The LOD and LOQ of five pregnane compounds were found to be in the range of 1–5 and 3–15 μg/mL, respectively, by HPLC using photodiode array detection. This method was applied to the identification of three plant materials of Caralluma species (C. fimbriata, C. umbellate, and C. attentuata) and seven dietary supplements claiming to contain C. fimbriata. An LC/MS coupled with electrospray ionization interface method was used for the identification of compounds and involved the use of [M+Na]+ ions in the positive ion mode with extracted ion chromatogram.
Determination of Major Phenolic Compounds in Echinacea spp. Raw Materials and Finished Products by High-Performance Liquid Chromatography with Ultraviolet Detection: Single-Laboratory Validation Matrix Extension
Authors: Brown Paula N , Chan Michael , Paley Lori , Betz Joseph M
Published: February 2020

A method previously validated to determine caftaric acid, chlorogenic acid, cynarin, echinacoside, and cichoric acid in echinacea raw materials has been successfully applied to dry extract and liquid tincture products in response to North American consumer needs. Single-laboratory validation was used to assess the repeatability, accuracy, selectivity, LOD, LOQ, analyte stability (ruggedness), and linearity of the method, with emphasis on finished products. Repeatability precision for each phenolic compound was between 1.04 and 5.65% RSD, with HorRat values between 0.30 and 1.39 for raw and dry extract finished products. HorRat values for tinctures were between 0.09 and 1.10. Accuracy of the method was determined through spike recovery studies. Recovery of each compound from raw material negative control (ginseng) was between 90 and 114%, while recovery from the finished product negative control (maltodextrin and magnesium stearate) was between 97 and 103%. A study was conducted to determine if cichoric acid, a major phenolic component of Echinacea purpurea (L.) Moench and E. angustifolia DC, degrades during sample preparation (extraction) and HPLC analysis. No significant degradation was observed over an extended testing period using the validated method.
Development and Validation of a Reversed-Phase Column Liquid Chromatographic Method for the Determination of Five Cephalosporins in Pharmaceutical Preparations
Authors: Elkady Ehab F , Abbas Samah S
Published: February 2020

A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters μBondapak® C18 column (250 × 4.6 mm id, 10 μm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)–acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30–300, 3–30, and 15–120 μg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.
Aflatoxin Plate Kit
Authors: Trombley Arthur , Fan Titan , LaBudde Robert
Published: February 2020

The level of total aflatoxin contamination was analyzed in naturally contaminated and spiked samples of corn and peanut using the Aflatoxin Plate Kit. This kit is an enzyme-linked immunosorbent assay (ELISA) suitable for rapid testing of grains and peanuts. The assay was evaluated for ruggedness and linearity of the standard curve. The test kit results were then statistically evaluated for accuracy, precision, and correlation to a validated HPLC method (AOAC 994.08). The results were verified by an independent laboratory.
Enzyme-Linked Immunosorbent Assay for Okadaic Acid: Investigation of Analytical Conditions and Sample Matrix on Assay Performance
Authors: Wang Li , Sang Ya-Xin , Wang Xiang-Hong
Published: February 2020

Okadaic acid (OA) is a lipophilic marine biotoxin. In this study, OA was coupled with the carrier proteins keyhole limpet hemocyanin and bovine serum albumin as immunity and detection antigens by an active ester method. The polyclonal antibody against OA was prepared successfully, an indirect competitive ELISA (ciELISA) developed for the detection of OA in shellfish, and the reactive conditions of ciELISA optimized. The LOD (15% inhibition concentration) for the microwell plates was 1.28±0.38 ng/mL, corresponding to 12.8±3.8 ng/g. Two extraction methods were used to remove shellfish matrix interference with high recovery of spiked samples, and the methanol extraction of shellfish mussel was analyzed after dilution in phosphate-buffered saline. For validation of the optimized ciELISA, spiked and natural samples were analyzed by ciELISA, and HPLC with fluorescence detection. The correlation of linear regression equation was y=1.0064x–10.234, and the correlation coefficient was 0.9347. From the results of the comparative study, the established ciELISA assay using polyclonal antibody against OA could be used in preliminary screening of suspicious shellfish samples.
Diarrhea may be underestimated: a missing link in 2019 novel coronavirus
Authors: Liang Weicheng , Feng Zhijie , Rao Shitao , Xiao Cuicui , Lin Ze-Xiao , Zhang Qi , Wei Qi
Published: February 2020

The outbreak of pneumonia caused by the 2019 Novel Coronavirus (2019-nCoV) was reported in Wuhan City, China. However, the clinical symptoms varied in different reports. Based on results of inter-group difference test, we found that the incidence of diarrhea differed in three recent reports. As 2019-nCoV utilizes the same cell entry receptor ACE2 as severe acute respiratory syndrome coronavirus (SARS-CoV) and ACE2 tightly controls intestinal inflammation, to trace the route of infection mediated by 2019-nCoV, we used the single-cell RNA sequencing data for analysis. We found that the ACE2 mRNA was highly expressed in the healthy human small intestine rather than the lung. Besides, single-cell RNA sequencing data showed that ACE2 was significantly elevated in the proximal and distal enterocytes, where the small intestinal epithelium is exposed to the foreign pathogen. Thus, we suspect that ACE2-expressing small intestinal epithelium cells might be vulnerable to 2019-nCoV infection when people eat infected wild animals and diarrhea may serve as an indicator for infection, suggesting that clinicians should pay more attention to patients with diarrhea during the outbreak of pneumonia.
Tracing Evolutionary Ages of Cancer-Driving Sites by Cancer Somatic Mutations
Authors: Gu Xun , Zou Zhan , Yang Jingwen
Published: February 2020

Evolutionary understanding of cancer genes may provide insights on the nature and evolution of complex life and the origin of multicellularity. In this study, we focus on the evolutionary ages of cancer-driving sites, and try to explore to what extent the amino acids of cancer-driving sites can be traced back to the most recent common ancestor (MRCA) of the gene. According to gene phylostraigraphy analysis, we use the definition of gene age (tg) by the most ancient phylogenetic position that can be traced back, in most cases based on the large-scale homology search of protein sequences. Our results are shown that the site-age profile of cancer-driving sites of TP53 is correlated with the number of cancer types the somatic mutations may affect. In general, those amino acid sites mutated in most cancer types are much ancient. These sites frequently mutated in cancerous cells are possibly responsible for carcinogenesis; some may be very important for basic growth of single-cell organisms, and others may contribute to complex cell regulation of multicellular organisms. The further cancer genomics analysis also indicates that ages of cancer-driving sites are ancient but may have a broad range in early stages of metazoans.