bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiresidue Method for Simultaneous Determination of Ten Quinolone Antibacterial Residues in Multimatrix/Multispecies Animal Tissues by Liquid Chromatography with Fluorescence Detection: Single Laboratory Validation Study
Authors: Verdon Eric , Couedor Pierrick , Roudaut Brigitte , Sandérs Pascal
Published: February 2020

Quinolone antibacterials are veterinary drugs authorized for use in food animal production. The analysis of residual amounts of drugs in food from animal origin is important for quality control of products for consumers. For this purpose, Maximum Residue Limits (MRLs) have been set up by a European Union Council Regulation on Veterinary Drug Residues (No. 90/2377/EEC and subsequent), and 8 quinolones received MRLs at concentration levels depending on both the matrix and the animal species of interest. A method was developed for screening and confirming 10 quinolone residues (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, oxolinic acid, sarafloxacin) in a wide variety of matrixes of different animal species. It involves extraction of the residues from the biological tissues/fluids by acidic aqueous solution, centrifugation and filtration prior to injection on a C18 narrow-bore column, and detection through a 3-step-mode fluorescence detector. The method was validated during a 2-week study for a set of 8 species-matrixes (i.e., bovine raw milk, bovine muscle, porcine muscle, porcine kidney, porcine liver, fish flesh and skin, poultry muscle, whole egg). Residues were quantified down to 15 μg/kg with limits of detection and quantitation ranging from 4 to 11 and 13 to 36 μg/kg, respectively, which are sufficient compared to the wide range of MRLs set for these substances (from 30 μg/kg for danofloxacin in milk to 1900 μg/kg for difloxacin in poultry liver). The limit of performance of the method in terms of CCα and CCβ, the critical concentrations stated in the Decision No. 2002/657/EC and the ISO Standard No. 11843, has been calculated for the authorized (MRL) substances but only estimated in the case of the nonauthorized (non-MRL) substances.
Determination of Deoxynivalenol in Cereals and Cereal Products by Immunoaffinity Column Cleanup with Liquid Chromatography: Interlaboratory Study
Authors: MacDonald Susan J , Chan Danny , Brereton Paul , Damant Andrew , Wood Roger ,   Collaborators:, Dao Duy K , Felgueiras I , Feron T , Herry M-P , Ioannou-Kakouri E , Koch P , Krska R , Majerus P , Nesbit J , Reuter M , Stangroom S , Symonds P , Weber R
Published: February 2020

An interlaboratory study was performed on behalf of the UK Food Standards Agency to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatographic (LC) method for the determination of deoxynivalenol in a variety of cereals and cereal products at proposed European regulatory limits. The test portion was extracted with water. The sample extract was filtered and applied to an immunoaffinity column. After being washed with water, the deoxynivalenol was eluted with acetonitrile or methanol. Deoxynivalenol was quantitated by reversed-phase LC with UV determination. Samples of artificially contaminated wheat-flour, rice flour, oat flour, polenta, and a wheat based breakfast cereal, naturally contaminated wheat flour, and blank (very low level) samples of each matrix were sent to 13 collaborators in 7 European countries. Participants were asked to spike test portions of all samples at a range of deoxynivalenol concentrations equivalent to 200–2000 ng/g deoxynivalenol. Average recoveries ranged from 78 to 87%. Based on results for 6 artificially contaminated samples (blind duplicates), the relative standard deviation for repeatability (RSDr) ranged from 3.1 to 14.1%, and the relative standard deviation for reproducibility (RSDR) ranged from 11.5 to 26.3%. The method showed acceptable within-laboratory and between-laboratory precision for all 5 matrixes, as evidenced by HorRat values <1.3.
Preconcentration and Determination of Tellurium in Garlic Samples by Hydride Generation Atomic Absorption Spectrometry
Authors: Kaplan Marcos M , Cerutti Soledad , Salonia José A , Gásquez José A , Martinez Luis D
Published: February 2020

A procedure for the determination of traces of total tellurium (Te) in garlic (Allium sativa) is described that combines hydride generation atomic absorption spectrometry with preconcentration of the analyte by coprecipitation. The samples, each spiked with lanthanum nitrate (20 mg/L), are introduced into an Amberlite XAD-4 resin and mixed with ammonium buffer (pH 9.1). Te is preconcentrated by coprecipitation with the generated lanthanum hydroxide precipitate. The precipitate is quantitatively collected in the resin, eluted with hydrochloric acid, and then transferred into the atomizer device. Considering a sample consumption of 25 mL, an enrichment factor of 10 was obtained. The detection limit (3σ) was 0.03 μg/L, and the precision (relative standard deviation) was 3.5% (n = 10) at the 10 μg/L level. The calibration graph using the preconcentration system for Te was linear with a correlation coefficient of 0.9993. Satisfactory results were obtained for the analysis of Te in garlic samples.
Liquid Chromatographic Determination ofMalachite Green and Leucomalachite Green (LMG) Residues in Salmon with in situ LMG Oxidation
Authors: Andersen Wendy C , Roybal José E , Turnipseed Sherri B
Published: February 2020

A liquid chromatography (LC) method is presented for the quantitative determination of malachite green (MG) in salmon. MG and leucomalachite green (LMG) residues were extracted from salmon tissue with ammonium acetate buffer and acetonitrile, and then isolated by partitioning into dichloromethane. LMG was quantitatively oxidized to the chromic MG by reaction with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Samples were then cleaned up by solid-phase extraction with alumina and propylsulfonic acid phases. Extracts were analyzed for MG by LC with visible detection at 618 nm using isocratic elution and a C18 column. The method was validated in 35 farm-raised salmon (Salmo salar) tissues fortified at 1, 2, 4, and 10 ng/g (ppb) with an average recovery of 95.4% and a relative standard deviation of ±11.1%, and in 5 canned salmon (Oncorhynchus gorbuscha) samples fortified at 10 ng/g with an average recovery of 88.9 ± 2.6%. This study also included the determination of MG and LMG residues in tissues from salmon that had been treated with MG. MG was quantitatively determined at the method detection limit of 1 ng/g.
Determination and Confirmation of Malachite Green and Leucomalachite Green Residues in Salmon Using Liquid Chromatography/Mass Spectrometry with No-Discharge Atmospheric Pressure Chemical Ionization
Authors: Turnipseed Sherri B , Andersen Wendy C , Roybal José E
Published: February 2020

A liquid chromatography/mass spectrometry (LC/MS) method was developed to quantitate and confirm residues of leucomalachite green (LMG) in salmon tissue after their conversion to chromic malachite green (MG) in the extraction process. The method uses no-discharge atmospheric pressure chemical ionization (APCI) in conjunction with an ion-trap instrument to generate product-ion spectra. In the sample preparation procedure, salmon tissue is extracted with acetonitrile/buffer, the LMG residue is partitioned into methylene chloride, the LMG is converted to MG using an organic oxidizing agent, and the MG is isolated on alumina/propylsulfonic acid solid-phase extraction cartridges. The method was validated by fortifying salmon with different levels of LMG, and then detecting the residue as MG. The LC/MS conditions, including a comparison of electrospray and no-discharge APCI, were evaluated and optimized. MG was not confirmed in any of the control tissue extracts, and all fortified samples analyzed during validation met the confirmation criteria as described. In addition to providing confirmatory data, this method can provide an alternative method for quantitation of MG in salmon. The recoveries of LMG, measured as MG by this LC/MS method, at fortification levels of 1–10 ng/g were very high (86–109%), with low relative standard deviation(RSD) values (6.4–13%). The results agreed very closely with those obtained for the same extracts using an LC/VIS procedure, indicating that matrix suppression was not an issue. The presence of LMG in salmon tissue samples fortified at 0.25 ng/g was confirmed by this method, with an average recovery of 70.1% and an RSD of 12.0%. Sample extracts from fish exposed to MG were also analyzed.
Determination of Ionization Constant (pKa) and Octanol–Water Partition Coefficient (Log P) of Cyclopiazonic Acid
Authors: Sobolev Victor S
Published: February 2020

The ionization constant (pKa) and the octanol–water partition coefficient (log P) of the important mycotoxin cyclopiazonic acid (CPA) were determined by means of potentiometric titration, and the lipophilicity profile (log D) was calculated. Under the experimental conditions, pKa of CPA = 2.97 ± 0.09, log P = 3.83 ± 0.10, and log D at pH 7.4 = −0.58.
Determination of Trace Amounts of Cobalt Using 1-(5-Bromo-2-Pyridylazo)-2-Naphthol-6-Sulfonic Acid-Cu(II)-Co(II) Competitive Replacement Complexation
Authors: Gao Hong-Wen
Published: February 2020

The chromophore 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid (BPANS) has been used to sensitively complex Cu(II) and Co(II) in aqueous solution at pH 9.43. The spectral correction technique was applied to characterize the complexes, and results showed that both Cu(BPANS)2 and Co(BPANS)2 were formed. Trace Co2+ replaced the Cu(II) in the Cu-BPANS complex, so the competitive replacement complexation (CRC) was used to improve the analytical selectivity. A novel light-absorption ratio variation approach (LARVA) was described as one of the most sensitive methods. The combination of CRC and LARVAwas applied to the quantitative detection of Co(II) at the ng/mL level. The limit of detection was only 2.0 ng/mL Co, and the analysis of water samples demonstrated satisfactory results.
Multiresidue Determination of Pesticides in Sediment by Ultrasonically Assisted Extraction and Gas Chromatography/Mass Spectrometry
Authors: Kawata Kuniaki , Asada Takashi , Oikawa Kikuo , Tanabe Akiko
Published: February 2020

Agas chromatographic/mass spectrometric (GS/MS) method was developed for the multiple determination of pesticides in sediment. The investigated pesticides included 85 compounds, i.e., 13 fungicides, 43 herbicides, and 29 insecticides. The pesticides were extracted from sediment samples by an ultrasonically assisted procedure. The extract was cleaned up by using reversed-phase column chromatography followed by normal-phase column chromatography. A styrene-divinylbenzene copolymer cartridge and a silica gel cartridge were used as the reversed-phase column and the normal-phase column, respectively. The compounds were determined by GC/MS with 2 internal standard compounds. The overall recoveries were 70–105%, and the relative standard deviations ranged from 1.5 to 18%. The minimum detectable concentrations were 2–10 μg/kg. This method was successfully applied to sediment samples from the Shin River in Niigata, Japan. Twenty-five pesticides (6 fungicides, 11 herbicides, and 8 insecticides) were detected in the sediment samples. The concentrations of the detected pesticides ranged from 3 to 69 μg/kg. Herbicides were found May through July; insecticides and fungicides were found July through August, and during July through September, respectively. The presence of pesticides in the river sediment was correlated with the time of pesticide application in the Shin River basin.
High-Performance Thin-Layer Chromatography with Densitometry for the Determination of Ciprofloxacin and Impurities in Drugs
Authors: Krzek Jan , Hubicka Urszula , Szczepańczyk Justyna
Published: February 2020

A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform–methanol–25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO–methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 μg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.
Identification and Quantitation of Polymyxin B, Framycetin, and Dexamethasone in an Ointment by Using Thin-Layer Chromatography with Densitometry
Authors: Krzek Jan , Maślanka Anna , Lipner Pawel
Published: February 2020

A new thin-layer chromatographic-densitometric method has been developed for rapid identification and quantitative determination of polymyxin B, framycetin, and dexamethasone in a dental ointment. Silica gel 60 and F254 silica gel 60 plates were used for separating antibiotics and dexamethasone acetate, respectively. When determining framycetin and polymyxin B, chromatograms were developed by using 2 mobile phases, namely methanol and methanol–n-butanol–ammonia (25%)–chloroform (14 + 4 + 9 + 12, v/v/v/v/). The densitometric measurements were made at 550 nm after detection with 0.3% ninhydrin solution. Dexamethasone was determined by using the mobile phase cyclohexane–ethyl acetate (2 + 3, v/v) and ultraviolet densitometric recording at 245 nm. The results obtained for individual constituents with the chromatographic-densitometric method demonstrate similar accuracy, relative standard deviation values from 1.49 to 2.47%, and relative error values from 0.02 to 0.81% and are comparable to those obtained with the reference methods.
Development and Validation of a Thin-Layer Chromatographic Method for Determination of Chloramphenicol Residues on Pharmaceutical Equipment Surfaces
Authors: Vovk Irena , Simonovska Breda
Published: February 2020

A thin-layer chromatographic (TLC) method with densitometric quantitation using the absorption reflectance mode at 280 nm was developed and validated for the determination of chloramphenicol residues in controlling pharmaceutical equipment cleanliness. Simulated samples at residue levels 0.5, 1, and 1.2 mg/m2 were prepared by spreading the calculated amount of chloramphenicol solution on a 10 dm2 stainless steel surface. After evaporation of the solvent, the residue was removed by 2 methanol-wetted cotton swabs, which were then extracted with methanol. The extract was applied on a high-performance TLC (HPTLC) silica gel F254 plate together with standards ranging from 10 to 60 ng. Plates were developed in a horizontal developing chamber from both sides (36 applications per plate) by using n-hexane–ethyl acetate (35 + 65, v/v) as developing solvent. The mean recovery (n = 6) at 1 mg/m2 was 95.8%, and the coefficient of variation was 5.8%. The absolute detection limit was 3 ng, and the quantitation limit 10 ng. The method detection limit was 0.3 mg/m2 by swabbing 2.5 dm2 and 0.075 mg/m2 by swabbing 10 dm2. Chloramphenicol was stable on the plate 2 h before and 24 h after development. Additionally, it was stable during 7 days storage on the cotton swabs in the solvent at room temperature and in diluted standard solution stored in darkness at 4°C. The method can be applied to routine control of pharmaceutical equipment cleanliness by sampling from the stainless steel surface areas of 2.5 to 10 dm2, and an acceptable residue limit of 1 mg/m2.
Spectrofluorimetric Determination of Acetaminophen with N-Bromosuccinimide
Authors: Abdel-Wadood Hanaa M , Mohamed Niveen A , Mohamed Fardous A
Published: February 2020

A simple, sensitive, and selective method for determination of acetaminophen based on its oxidation using N-bromosuccinimide (NBS) to produce a highly fluorescent product. Optimization of reaction variables was carried out concerning NBS concentration, pH, temperature, reaction time, and stability time. Under optimal analytical conditions, the fluorescent intensity was measured at λemission. 442 nm (excitation at λ 330 nm). The linearity range is 120–800 ng/mL with lower detection limit of 33.6 ng/mL acetaminophen. The method was applied successfully to the determination of the compound in pharmaceutical preparations, with average recovery of 100.3 ± 2%. The method was also applied successfully to the determination of the drug in spiked plasma samples, with an average recovery of 101.2 ± 1%. Interference effects of some compounds, present in combination with acetaminophen, were studied and the tolerance limits of these compounds were determined.
Spectrophotometric Study of Etodolac Complexes with Copper (II) and Iron (III)
Authors: Amer Sawsan M , El-Saharty Yasser S , Metwally Fadia H , Younes Kareem M Younes
Published: February 2020

A rapid, simple, and selective method was developed for the determination of etodolac. The method depends on complexation of etodolac with copper (II) acetate and iron (III) chloride followed by extraction of complexes with dichloromethane and then measuring the extracted complexes spectrophotometrically at 684 and 385 nm in case of Cu (II) or Fe (III), respectively. Different factors affecting the reaction, such as pH, reagent concentration, and time, were studied. By use of Job's method of continuous variation, the molar ratio method, and elemental analysis, the stoichiometry of the reaction was found to be in the ratio of 1:2 and 1:3, metal:drug in the case of Cu (II) and Fe (III), respectively. The method obeys Beer's law in a concentration range of 2.00–9.00 and 0.50–2.00 mg/mL in case of Cu (II) and Fe (III), respectively. The stability of the complexes formed was also studied, and the reaction products were isolated for further investigation. The complexes have apparent molar absorptivities of about 32.14 ± 0.97 and 168.32 ± 1.12 for Cu (II) and Fe (III), respectively. The suggested procedures were successfully applied to the analysis of pure etodolac and its pharmaceutical formulations. The validity of the procedures was further ascertained by the method of standard additions, and the results were compared with other reported spectrophotometric methods and showed no significant difference in accuracy and precision.
Residue Analysis for Halofuginone in Sturgeon Muscle by Immunoaffinity Cleanup and Liquid Chromatography
Authors: Ding Shuangyang , Hou Yali , Wu Ningpeng , Shen Jiangzhong
Published: February 2020

A high-performance liquid chromatography (LC) method was developed for the determination of halofuginone (HFG) in sturgeon muscle. The extracted samples were cleaned up by an immunoaffinity chromatography column that was prepared by covalently coupling polyclonal antibodies against HFG to cyanogen bromide (CNBr) activated Sepharose 4B. The eluate was evaporated to dryness, and residues were determined by LC with absorbance detection at 243 nm. Recoveries of HFG from samples fortified at 20–200 μg/kg levels ranged 74.6–81.1%, with coefficients of variation of 0.7–8.6%. The detection limit was estimated to be 10 μg/kg in a 2 g sample.
Simultaneous Determination of Chlorpheniramine Maleate and Dexamethasone in a Tablet Dosage Form by Liquid Chromatography
Authors: Moyano María A , Rosasco María A , Pizzorno María T , Segall Adriana I
Published: February 2020

An accurate, simple, reproducible, and sensible liquid chromatographic method was developed and validated for the determination of chlorpheniramine maleate and dexamethasone in a tablet formulation. The analysis was performed at room temperature on a reversed-phase C18 column with UV detection at 254 nm. The mobile phase consisted of 7.5 mM monobasic potassium phosphate in methanol–water (62.5 + 37.5) at a constant flow rate of 1 mL/min. The method was validated in terms of linearity, precision, accuracy, and specificity by forced decomposition of chlorpheniramine maleate and dexamethasone initiated by using acid, base, water, hydrogen peroxide, heat, and light. The response was linear in the ranges of 0.04–0.12 and 0.006–0.016 mg/mL for chlorpheniramine maleate (r2 = 0.9999) and dexamethasone (r2 = 0.9994), respectively. The relative standard deviation values for intra- and interday precision studies were 2.39 and 2.02, respectively, for chlorpheniramine maleate and 2.39 and 1.25, respectively, for dexamethasone. Recoveries ranged from 95.07 to 101.95% for chlorpheniramine maleate and from 97.75 to 102.10% for dexamethasone.
Improved Method for the Determination of Anatoxin-a and Two of Its Metabolites in Blue-Green Algae Using Liquid Chromatography with Fluorescence Detection
Authors: Rawn Dorothea F K , Lau Benjamin P-Y , Niedzwiadek Barbara , Lawrence James F
Published: February 2020

Anatoxin-a, a neurotoxin produced by blue-green algae (BGA) species, can cause death to exposed organisms. In North America, BGA are harvested and sold as food supplements, some of which contain elevated levels of other algal toxins, such as microcystins. Concern that elevated levels of anatoxin-a also may be present in BGA food supplements has led to the development of a simple method to determine the presence of anatoxin-a in BGA. Some researchers have successfully analyzed this compound using liquid chromatography with fluorescence detection by forming a fluorescent derivative with 4-fluoro-7-nitrobenzofurazan (NBD-F) in water and phytoplankton extracts. With this method, the background noise is high in BGA extracts due to the presence of co-extractives. Addition of o-phthaldialdehyde (OPA) and mercaptoethanol to the extract before addition of the NBD-F resulted in the successful removal of primary amines from the background noise when the NBD-F derivatives were detected with fluorescence. Improved chromatograms were obtained when extracts were cleaned up in this manner, leading to a lower detection limit (approximately 50 μg/kg) for anatoxin-a. The detection limits obtained for the 2 degradation products dihydroanatoxin-a and epoxyanatoxin-a in BGA extracts were similarly low (55 and 65 μg/kg, respectively).
Determination of Fludioxonil and Famoxadone in Processed Fruits and Vegetables by Liquid Chromatography/Electrospray Tandem Mass Spectrometry
Authors: Sannino Anna , Bandini Mirella
Published: February 2020

The feasibility of using liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) for determining 2 fungicides (fludioxonil and famoxadone) in tomato pulp, pear purée, and concentrated lemon juice has been evaluated. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents was used. The extracts (5 μL) were analyzed by LC/ESI-MS/MS without previous cleanup. Chromatographic determination was performed using a C18 column with isocratic elution. Four MS/MS transitions of precursor ions were monitored simultaneously (2 for each pesticide) by means of negative ESI. Mean recoveries from samples at fortification levels of 0.002–0.020 mg/kg (fludioxonil) and 0.010–0.100 mg/kg (famoxadone) ranged from 77.1 to 96.5%, with associated relative standard deviations between 4.2 and 11.5%.
Species Identification of Crassostrea and Ostrea Oysters by Polymerase Chain Reaction Amplification of the 5S rRNA Gene
Authors: Cross Ismael , Rebordinos Laureana , Diaz Edgardo
Published: February 2020

A specific multiplex polymerase chain reaction (PCR) was developed for the identification of Crassostrea angulata, C. gigas, Ostrea edulis, and O. stentina oyster species. Universal primers were used for the amplification of complete repetition units of 5S rDNA in each of the 4 species. The alignment of the obtained sequences was the basis for the specific design of species-specific primers (ED1, ED2, ST1, ST2, CR1, and CR2) located in the nontranscribed spacer regions. The different sizes of the species-specific amplicons, separated by agarose gel electrophoresis, allowed identification of Crassostrea and Ostrea species. A multiplex PCR with a set of the 6 designed primers showed that they did not interfere with each other and bound specifically to the DNA target. This genetic marker can be very useful for traceability of the species, application in the management of oyster cultures, and conservation of the genetic resources of the species.
Determination of Acrylamide Formed in Asparagine/d-Glucose Maillard Model Systems by Using Gas Chromatography with Headspace Solid-Phase Microextraction
Authors: El-Ghorab Ahmed H , Fujioka Kazutoshi , Shibamoto Takayuki
Published: February 2020

A gas chromatographic method, along with a headspace solid-phase microextraction (HS-SPME), was developed for the determination of acrylamide formed in Maillard reaction model systems. The developed method was validated by liquid chromatography/mass spectrometry. A headspace sample was collected from an aqueous acrylamide solution (100 μg/mL) by SPME and directly injected into a gas chromatograph equipped with a nitrogen-phosphorus detector. The recovery of acrylamide from an aqueous solution was satisfactory, i.e, >93% under the conditions used. Acrylamide formed in an asparagine/d-glucose (molar ratio, 1/2) Maillard reaction model system heated at 150 and 170C for 20 min was collected and analyzed by the newly developed method using gas chromatography with nitrogen-phosphorus detection and HS-SPME. The amounts of acrylamide were 318 33 μg/g asparagine from a sample heated at 150C and 3329 176 g/g asparagine from a sample heated at 170C. Addition of cysteamine or glutathione to the above model system reduced acrylamide formation. Acrylamide formation was not observed when cysteamine or glutathione was added to asparagine in the above model systems to obtain equimolar concentrations of both compounds. This newly developed method is simple and sensitive, and requires no solvent extraction.
A Method for the Analysis of Ginsenosides, Malonyl Ginsenosides, and Hydrolyzed Ginsenosides Using High-Performance Liquid Chromatography with Ultraviolet and PositiveMode Electrospray IonizationMass Spectrometric Detection
Authors: Sloley Brian Duff , Lin Yi-Chan James , Ridgway Douglas , Semple Hugh Alexander , Tam Yun Kau , Coutts Ronald Thomson , Löbenberg Raimar , Tam-Zaman Nuzhat
Published: February 2020

A high-performance liquid chromatographic separation coupled to diode array absorbance and positive mode electrospraymass spectrometric detection has been developed for the analysis of ginsenosides, malonyl ginsenosides, and hydrolyzed ginsenosides in extracts of Asian ginseng (Panax ginseng) and American ginseng (P. quinquefolius). The method is capable of separating, identifying, and quantifying the predominant ginsenosides found in heated alcoholic extracts of Asian and American ginseng roots routinely sold as nutraceuticals. It also separates and identifies the malonyl ginsenosides often found in cold alcoholic extracts of ginseng root and has the potential to quantify these compounds if pure standards are available. Furthermore, it can separate and identify ginsenoside hydrolysis products such as those readily produced in situations mimicking gastric situations, including those used for dissolution studies (i.e., 0.1 N HCl, 37C).
Determination of Campesterol, Stigmasterol, and beta-Sitosterol in Saw Palmetto RawMaterials and Dietary Supplements by Gas Chromatography: Single-Laboratory Validation
Authors: Sorenson Wendy R , Sullivan Darryl
Published: February 2020

In conjunction with an AOAC Presidential Task Force on Dietary Supplements, a method was validated for measurement of 3 plant sterols (phytosterols) in saw palmetto raw materials, extracts, and dietary supplements. AOAC Official Method 994.10, Cholesterol in Foods, was modified for purposes of this validation. Test samples were saponified at high temperature with ethanolic potassium hydroxide solution. The unsaponifiable fraction containing phytosterols (campesterol, stigmasterol, and beta-sitosterol) was extracted with toluene. Phytosterols were derivatized to trimethylsilyl ethers and then quantified by gas chromatography with a hydrogen flame ionization detector. The presence of the phytosterols was detected at concentrations greater than or equal to 1.00 mg100 g based on 23 g of sample. The standard curve range for this assay was 0.00250 to 0.200 mgmL. The calibration curves for all phytosterols had correlation coefficients greater than or equal to 0.995. Precision studies produced relative standard deviation values of 1.52 to 7.27% for campesterol, 1.62 to 6.48% for stigmasterol, and 1.39 to 10.5% for beta-sitosterol. Recoveries for samples fortified at 100% of the inherent values averaged 98.5 to 105% for campesterol, 95.0 to 108% for stigmasterol, and 85.0 to 103% for beta-sitosterol.
Scoring in Genetically Modified Organism Proficiency Tests Based on Log-Transformed Results
Authors: Thompson Michael , Ellison Stephen L R , Owen Linda , Mathieson Kenneth , Powell Joanne , Key Pauline , Wood Roger , Damant Andrew P
Published: February 2020

The study considers data from 2 UK-based proficiency schemes and includes data from a total of 29 rounds and 43 test materials over a period of 3 years. The results from the 2 schemes are similar and reinforce each other. The amplification process used in quantitative polymerase chain reaction determinations predicts a mixture of normal, binomial, and lognormal distributions dominated by the latter 2. As predicted, the study results consistently follow a positively skewed distribution. Log-transformation prior to calculating z-scores is effective in establishing near-symmetric distributions that are sufficiently close to normal to justify interpretation on the basis of the normal distribution.
Generic Nonextractive Spectrophotometric Method for Determination of 4-Quino-Naphthollone Antibiotics by Formation of Ion-Pair Complexes with -Naphthol
Authors: Darwish Ibrahim A , Refaat Ibrahim H , Askal Hassan F , Marzouq Mostafa A
Published: February 2020

This paper describes the development of a generic spontaneous nonextractive spectrophotometric method for determination of 13 pharmaceutically important 4-quinolone antibiotics. The method was based on the formation of yellow-colored water-soluble ion-pair complexes between 2% (w/v) -naphthol reagent and each of the studied drugs in sulfuric acid medium at room temperature. The formed ion-pair chromogens have maximum absorption peaks in the range of 365391 nm. The concentrations of the reagents and the experimental conditions affecting the reaction were optimized. Under the optimum conditions, linear relationships with good linear coefficients (0.99870.9995) were found between the absorbance and concentration of the investigated drugs in the range of 10350 g/mL. The assay limits of detection and quantitation were 19.9 and 3.432.9 g/mL, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. The proposed method was successfully applied to the analysis of the investigated drugs in pure and pharmaceutical dosage forms with good accuracy and precision; the percentages of label claim ranged from 97.8102.8 0.351.60%. The results obtained by the proposed spectrophotometric method were comparable with those obtained by the official or reported methods. The proposed method is superior to all the previously reported ion-pair formation-based methods in terms of simplicity because it did not involve extraction procedures for the ion-pair complex. Therefore, this method might be recommended for routine use in quality control laboratories for analysis of the investigated 4-quinolone antibiotics in their pure forms, as well as in pharmaceutical dosage forms.
Reversed-Phase High-Performance Liquid Chromatography Determination of Selected Phenolic Acids in Propolis Concentrates in Terms of Standardization For Drug Manufacturing Purposes
Authors: Krzek Jan , Kaleta Jolanta , Hubicka Urszula , Niedzwiedz Aneta
Published: February 2020

A reversed-phase high-performance liquid chromatography method with gradient elution was developed for the determination of the caffeic, p-coumaric, and ferulic acids in propolis concentrates. Solid-phase extraction on an RP18 column was applied for preliminary purification, and chromatographic separation was performed on 100 RP18e Lichrospher column of particle size 5 m. The mobile phase was obtained by mixing in appropriate ratios 0.03 mM NaH2PO4, acidified with H3PO4 up to pH 3.0, with acetonitrile to obtain a gradient in the elution process. Spectrophotometric detection was conducted at 320 nm. Under the established conditions, the method featured high sensitivity, good precision, and comparability of results, as proven by method validation and statistical analysis of the obtained results. The limits of detection were 0.315, 0.325, and 0.695 g/mL for caffeic, p-coumaric, and ferulic acids, respectively. The corresponding recovery values were 98.14, 101.05, and 99.42 and the linearity ranges from 1.31 to 99.18 g/mL, 1.52 to 119.16 g/mL, and 2.42 to 184.14 g/mL. The precision of the method was expresed by relative standard deviation values that did not exceed 3. It was also shown that the propolis concentrates under examination had similar antibacterial activity against Staphylococcus aureus ranging from 119.8 to 124.3 g/mL, contrary to model mixtures that showed no antibacterial activity.
SubcriticalWater Extraction and Determination of Nifedipine in Pharmaceutical Formulations
Authors: Richter Pablo , Toral Maria Ines , Toledo Carla
Published: February 2020

A rapid and simple continuous method for the extraction of nifedipine from tablets was developed by using pressurized hot water at 150C. This is the first time that subcritical water was applied to the extraction of low-polarity compounds in pharmaceutical analysis. The method is based on the increment in solubility of nifedipine in subcritical water. Extraction temperature and static and dynamic extraction time were optimized in order to reach quantitative extraction of the drug from the tablets. After extraction, the drug was determined by spectrophotometry by measuring absorbance at 338 nm. Accuracy and precision of themethodwere determined by analysis of 10 synthetic samples of pharmaceutical formulations preparedwith common tablet excipients. Recoverywas found to be 99.2with a relative standard deviation of 1.9, which indicates that the excipients of the formulation do not interfere in the determination. The method was applied to the determination of the drug content uniformity in tablets.
Singlepathr® Salmonella: Performance-Tested MethodSM 060401
Authors: Thompson Lisa , Lindhardt Charlotte , Odumeru Joseph , Eifert Joseph D
Published: February 2020

Singlepath® Salmonella is an immunochromatographic (lateral flow) assay for the presumptive qualitative detection of Salmonella spp. in food. The AOAC Performance-Tested MethodSM study evaluated Singlepath Salmonella as an effective method for the detection of Salmonella spp. in the following selected foods: dried skimmed milk, black pepper, dried pet food, desiccated coconut, cooked peeled frozen prawns, raw ground beef, and raw ground turkey. When the foods were inoculated with Salmonella spp. at levels ranging from low 0.23–1.08 colony forming units (CFU)/25 g to high (2.3–6.0 CFU/25 g), a Chi-square value of 0.9 indicated that there was no significant difference between Singlepath Salmonella and the ISO 6579:2002 reference method. Singlepath Salmonella gave a false-positive rate of 7.3% and a false-negative rate of 2.5%. For the inclusivity study, all 105 Salmonella serovars reacted with Singlepath Salmonella. For the exclusivity study, 58 non-Salmonella spp. were tested. There were no cross-reactions with Singlepath Salmonella from these strains.
Influence of White Reference Measurement and Background on the Color Specification of Orange Juices by Means of Diffuse Reflectance Spectrophotometry
Authors: Melndez-Martnez Antonio J , Vicario Isabel M , Heredia Francisco J
Published: February 2020

The color of citrus beverages, in general, is related to the consumers' perception of flavor, sweetness, and other characteristics related to the quality of these products, so it is important to develop suitable methods for accurately assessing this attribute. In this study, the color of 2 different kinds of orange juices (ultrafrozen orange juices and orange juices from concentrate) were measured using different white references in order to demonstrate the influence of white reference measurement on the color parameters obtained. The results of this work indicated that the election of a wrong white reference measurement can affect dramatically the accuracy of the objective specification of orange juice color. Thus, the application of analysis of variance ( = 0.01) revealed that, in most cases, the parameters obtained were significantly different. In terms of color differences, the change of the background for the same white reference affected the measurements less than the changes of white references for the same background. On the other hand, important chromatic differences between the 2 types of orange juices studied were found.
Vitamin and Pseudovitamin Analysis with Biosensors in Food ProductsA Review
Authors: Kalman Andras , Caelen Isabelle , Svorc Jozef
Published: February 2020

Biosensors are becoming increasingly important in the food industry for application in safety and quality control among routinely used techniques such as microbiology, chromatography, or specific enzymatic methods. Biosensors offer advantages as alternatives to conventional methods because of their inherent specificity, simplicity, and rapid response. This article presents a short review of vitamin and pseudovitamin analysis techniques using biosensor technology as applied in the food industries, with particular attention to immobilization techniques of biorecognition elements, transducers, an overview of vitamin biosensors, and some future trends.
Rapid Analysis of Coumarins Using Surface Plasmon Resonance
Authors: Lacy Aoife , Dunne Lynsey , Fitzpatrick Brian , Daly Stephen , Keating Gary , Baxter Andrew , Hearty Stephen , O’kennedy Richard
Published: February 2020

Coumarin molecules are ubiquitous in nature. Several have come to prominence as potential clinical therapeutic candidates. The principal example is warfarin, which is a very widely prescribed anticoagulant. Other coumarin derivatives, such as aflatoxin B1, are insidious contaminants in crop-derived foodstuffs. Extreme potency is a common feature of all biochemically active coumarins and, thus reliable methods for their rapid and sensitive detection are of paramount importance. Accordingly, this review examines the current methods used in the analysis of these molecules and compares them with immunoassay-based strategies. As a case study, we report on our experiences with using coumarin-specific polyclonal, monoclonal, and recombinant antibodies in conjunction with a surface plasmon resonance-based biosensor for analysis of coumarins. We chart the assay development process and demonstrate high sensitivity and reproducibility that compares favorably with established methodologies.
Detection of Cashew Nut DNA in Spiked Baked Goods Using a Real-Time Polymerase Chain Reaction Method
Authors: Brzezinski Jennifer L
Published: February 2020

The detection of potentially allergenic foods, such as tree nuts, in food products is a major concern for the food processing industry. A real-time polymerase chain reaction (PCR) method was designed to determine the presence of cashew DNA in food products. The PCR amplifies a 67 bp fragment of the cashew 2S albumin gene, which is detected with a cashew-specific, dual-labeled TaqMan probe. This reaction will not amplify DNA derived from other tree nut species, such as almond, Brazil nut, hazelnut, and walnut, as well as 4 varieties of peanut. This assay was sensitive enough to detect 5 pg purified cashew DNA as well as cashew DNA in a spiked chocolate cookie sample containing 0.01% (100 mg/kg) cashew.
Assessing Exposure to Lignans and Their Metabolites in Humans
Authors: Lampe Johanna W , Atkinson Charlotte , Hullar Meredith A J
Published: February 2020

Phytoestrogens occur naturally in plants and are structurally similar to mammalian estrogens. The lignans are a class of phytoestrogen and can be metabolized to the biologically active enterolignans, enterodiol, and enterolactone by a consortium of intestinal bacteria. Secoisolariciresinol diglucoside (SDG), a plant lignan, is metabolized to enterodiol and, subsequently, enterolactone. Matairesinol, another plant lignan, is metabolized to enterolactone. Other dietary enterolignan precursors include lariciresinol, pinoresinol, syringaresinol, arctigenin, and sesamin. Enterolignan exposure is determined in part by intake of these precursors, gut bacterial activity, and host conjugating enzyme activity. A single SDG dose results in enterolignan appearance in plasma 810 h latera timeframe associated with colonic bacterial metabolism and absorption. Conjugation of enterolignans with sulfate and glucuronic acid occurs in the intestinal wall and liver, with the predominant conjugates wall and liver, with the predominant conjugates have demonstrated dose-dependent urinary lignan excretion in response to flaxseed consumption (a source of SDG); however, even in the context of controlled studies, there is substantial interindividual variation in plasma concentrations and urinary excretion of enterolignans. The complex interaction between colonic environment and external and internal factors that modulate it likely contribute to this variation. Knowledge of this field, to date, indicates that understanding the sources of variation and measuring the relevant panel of compounds are important in order to use these measures effectively in evaluating the impact of lignans on human health.
AReview of the Animal Models Used to Investigate the Health Benefits of Soy Isoflavones
Authors: Cooke Gerard M
Published: February 2020

This review considers the recent literature in which animal models were used to investigate the purported health benefits of soy isoflavones. The main conclusions are that our animal models demonstrate minimal effects in breast, prostate, and colon cancer prevention, and that, while some cancers may respond to isoflavones, it would appear that isoflavones do not prevent further development once cancer has become established. Regarding cardiovascular health, the lipid-lowering effects of isoflavones have been established, but their efficacy may be less than original research purported. However, it may be considered a bonus of habitual soy consumption that blood cholesterol levels would be reduced somewhat. With respect to osteoporosis and menopausal symptoms, animal models do not show any consistent benefit of isoflavones in preventing osteoporosis, and calcium fortification or the use of prescribed medications are likely much better approaches to combat bone loss. However, our animal models of osteoporosis and menopausal symptoms may not be entirely representative of the human situation. Perhaps the benefit of isoflavones in cognitive skills and in delaying Alzheimer's disease is an area where they can be of some advantage. However, this field is very recent and requires much more research in both humans and animal models before any definitive benefit can be propounded. On the other hand, isoflavones in moderation are probably not dangerous, as few studies have indicated adverse effects. However, large doses have been shown to increase apoptosis and cell degeneration, and in some cancer regimes, once the cancer has progressed beyond the hormone-dependent stage, high doses of isoflavones may be contraindicated. The prospect of mega-dosing from isoflavone supplements opens a new chapter in the risk assessment of isoflavone consumption.
Determination of Aristolochic Acid in Botanicals and Dietary Supplements by Liquid Chromatography with Ultraviolet Detection and by Liquid Chromatography/Mass Spectrometry: Single Laboratory Validation Confirmation
Authors: Trujillo William A , Sorenson Wendy R , Luzerne Paul La , Austad John W , Sullivan Darryl
Published: February 2020

The presence of aristolochic acid in some dietary supplements is a concern to regulators and consumers. A method has been developed, by initially using a reference method as a guide, during single laboratory validation (SLV) for the determination of aristolochic acid I, also known as aristolochic acid A, in botanical species and dietary supplements at concentrations of approximately 2 to 32 μg/g. Higher levels were determined by dilution to fit the standard curve. Through the SLV, the method was optimized for quantification by liquid chromatography with ultraviolet detection (LC-UV) and LC/mass spectrometry (MS) confirmation. The test samples were extracted with organic solvent and water, then injected on a reverse phase LC column. Quantification was achieved with linear regression using a laboratory automation system. The SLV study included systematically optimizing the LC-UV method with regard to test sample size, fine grinding of solids, and solvent extraction efficiency. These parameters were varied in increments (and in separate optimization studies), in order to ensure that each parameter was individually studied; the test results include corresponding tables of parameter variations. In addition, the chromatographic conditions were optimized with respect to injection volume and detection wavelength. Precision studies produced overall relative standard deviation values from 2.44 up to 8.26% for aristolochic acid I. Mean recoveries were between 100 and 103% at the 2 μg/g level, between 102 and 103% at the 10 μg/g level, and 104% at the 30 μg/g level.
Spectrophotometric, Difference Spectroscopic, and High-Performance Liquid Chromatographic Methods for the Determination of Cefixime in Pharmaceutical Formulations
Authors: Shah Paresh B , Pundarikakshudu Kilambi
Published: February 2020

Three simple and sensitive spectrophotometric, difference spectroscopic, and liquid chromatographic (LC) methods are described for the determination of cefixime. The first method is based on the oxidative coupling reaction of cefixime with 3-methyl-2-benzothiazolinon hydrazone HCl in presence of ferric chloride. The absorbance of reaction product was measured at the maximum absorbance wavelength (max), 630 nm. The difference spectroscopic method is based on the measurement of absorbance of cefixime at the absorbance maximum, 268 nm, and minimum, 237 nm. The measured value was the amplitude of maxima and minima between 2 equimolar solutions of the analyte in different chemical forms, which exhibited different spectral characteristics. The conditions were optimized, and Beer's law was obeyed for cefixime at 1 to 16 μg/mL and 10 to 50 μg/mL, respectively. The third method, high-performance LC, was developed for the determination of cefixime using 50 mM potassium dihydrogen phosphate (pH 3.0)methanol (78 + 22, v/v) as the mobile phase and measuring the response at λmax 286 nm. The analysis was performed on a Lichrospher RPC18 column. The calibration curve was obtained for cefixime at 5 to 250 μg/mL, and the mean recovery was 99.71 ± 0.01%. The methods were validated according to the guidelines of the U.S. Pharmacopoeia and also assessed by applying the standard addition technique. The results obtained in the analysis of dosage forms agreed well with the contents stated on the labels.