bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Determination of Dimethylaminoethanol in Cosmetic Formulations by Nuclear Magnetic Resonance Spectroscopy
Authors: Andradebatista Ivani Aparecida Soares De , Gonçalves Maria Inês De Almeida , Singh Anil Kumar , Hackmann Erika Rosamaria Kedor , Santoro Andmaria Inês Rochamiritello
Published: February 2020

A nuclear magnetic resonance (NMR) spectroscopic method was validated for the quantitative determination of dimethylaminoethanol (DMAE) in cosmetic formulations. The linearity in the range from 0.5000 to 1.5000 g (DMAE salt/mass maleic acid) presents a correlation coefficient >0.99 for all DMAE salts. The repeatability (intraday), expressed as relative standard deviation, ranged from 1.08 to 1.44 for samples and 1.31 to 1.88 for raw materials. The detection limit and quantitation limit were 0.0017 and 0.0051 g for DMAE, 0.0018 and 0.0054 g for DMAE bitartrate, and 0.0023 and 0.0071 g for DMAE acetamidobenzoate, respectively. The proposed method is simple, precise, and accurate and can be used in the quality control of raw materials and cosmetic gels containing these compounds as active substances.
Determination of Norfloxacin and Enrofloxacin by Solid-Phase Microextraction/High-Performance Liquid Chromatography
Authors: Kumar Ashwini , Dhingra Gaurav , Kumar malik Ashok , Tewary Dhananjay K
Published: February 2020

A solid-phase microextraction (SPME) method followed by separation with high-performance liquid chromatography and subsequent UV detection was developed for the determination of norfloxacin and enrofloxacin. The simple and sensitive preconcentration technique uses 280 nm wavelength in mobile phase of citrate buffer (0.01 M), pH 3.8, prepared in water (A) and acetonitrile (B), with composition of the mobile phase A:B, 40:60, at a flow rate of 1.0 mL/min. A C18 reversed-phase analytical column (5 m) was selected as separation medium for the technique. To obtain optimum extraction efficiency, several parameters relating to SPME were investigated. The method was linear over the range of 10100 ng/mL for norfloxacin and enrofloxacin with a correlation coefficient (R2) value of 0.9972 and 0.9980 for norfloxacin and enrofloxacin, respectively. Using the SPME method, the detection limits (signal-to-noise ratio 3) are 0.17 and 0.12 ng/mL for norfloxacin and enrofloxacin, respectively.
Sensitive Mercury Speciation by Reversed-Phase Column High-Performance Liquid Chromatography with UV-Visible Detection After Solid-Phase Extraction Using 6-Mercaptopurine and Dithizone
Authors: Hashemi-Moghaddam Hamid , Saber-Tehrani Mohamad
Published: February 2020

A highly selective and sensitive method was developed for preconcentration of inorganic and organic mercury compounds followed by reversed-phase column high-performance liquid chromatography (RP-HPLC) with UV-visible detection. The method was based on the reaction of mercury with 6-mercaptopurine and solid-phase extraction (SPE) of the complex on an octadecylsilane (C18) cartridge. The complex was then treated with ammoniacal dithizone solution, and the complexes of inorganic and organic mercury with dithizone were eluted by methanol. The speciation analysis of methylmercury (MeHg), phenylmercury (PhHg), and inorganic Hg (II) was carried out by RP-HPLC. Some experimental variables that influence the SPE and derivatization, such as pH, chelating and derivatizing agent concentration, and surfactant addition, were investigated. The calibration graphs of MeHg, PhHg, and Hg (II) were linear [correlation coefficient (r) > 0.999] from the detection limits (0.12, 0.16, and 0.14 ng) to 8.5, 6.0, and 6.7 ng Hg, respectively. By applying the SPE procedure, a 100-fold concentration of the sample was obtained. The procedure was applied to sea water and tuna fish samples. The method's accuracy was investigated by using tuna fish certified reference material BCR 464 and by spiking the samples with different amounts of MeHg, PhHg, and Hg (II). The average recoveries of MeHg, PhHg, and Hg (II) from spiked samples (0.12.0 g/L Hg) were 96 4, 98 3, and 104 4, respectively.
Column High-Performance Liquid Chromatographic Method for the Simultaneous Determination of Rosiglitazone and Metformin in a Pharmaceutical Preparation
Authors: Ali Azzam R , Duraidi Ibrahim I , Saket Munib M , Abu-Nameh Eyad S M
Published: February 2020

An efficient, sensitive, and simple method was developed for the simultaneous determination of rosiglitazone and metformin hydrochloride in a combination tablet dosage form by column high-performance liquid chromatography. The mobile phase used was ammonium dihydrogen phosphate adjusted to pH 5.25 with sodium hydroxide. The limits of detection and quantitation were in the range of 0.51.6 g/mL, respectively, for metformin hydrochloride, and 0.002010.0067 g/mL, respectively, for rosiglitazone. The linearity was studied in the concentration range of 0.120.31 g/mL for rosiglitazone and 30.676.7 g/mL for metformin hydrochloride. The recovered amounts of metformin hydrochloride and rosiglitazone were 100103.8 and 101103.7, respectively.
Refinement and Extension of AOAC Method 2005.06 to Include Additional Toxins in Mussels: Single-Laboratory Validation
Authors: Turner Andrew D , Norton Deirdre M , Hatfield Robert G , Morris Steven , Reese Allan R , Algoet Myriam , Lees David N
Published: February 2020

A single-laboratory validation study was undertaken for the analysis of paralytic shellfish poisoning (PSP) toxins in common mussels, extending AOAC Official Method 2005.06 to include the additional toxins dcNEO and dcGTX2,3. The method was refined to improve toxin oxidation product stability, analytical sensitivity of N-hydroxylated toxins, and throughput. Validation was performed to characterize the method for selectivity, sensitivity, linearity, precision, repeatability, recovery, ruggedness, and uncertainty. Parallel testing of naturally contaminated mussels enabled comparison of sample toxicities obtained using mouse bioassay (MBA) and high-performance liquid chromatographic (HPLC) methodologies. Performance characteristics of the method are reported for all commercially available certified reference toxins. Results from the MBA and HPLC methods were well correlated, and the analytical method has been instigated as the sole monitoring tool for UK official control surveillance of PSP toxins in common mussels.
Determination of Nine Intense Sweeteners in Foodstuffs by High-Performance Liquid Chromatography and Evaporative Light-Scattering Detection: Interlaboratory Study
Authors: Buchgraber Manuela , Wasik Andrzej ,   Collaborators:, Casal S , Dubois A , Gutsche B , Hanewinkel-Meshkini S , Martin D , Naas D
Published: February 2020

An interlaboratory trial was conducted to validate an analytical method based on high-performance liquid chromatographic analysis with evaporative light-scattering detection for the simultaneous determination of 9 intense sweeteners, i.e., acesulfame-K, alitame, aspartame, cyclamic acid, dulcin, neotame, neohesperidine dihydrochalcone, saccharin, and sucralose in carbonated and noncarbonated soft drinks and canned or bottled fruits. Seven laboratories participated in the validation study. The majority of the samples fortified with levels close to the limit of quantification had relative standard deviation for reproducibility (RSDR) values <15. In most cases, the recovery rates ranged between 90 and 105, demonstrating satisfactory performance of the method. For samples fortified at levels comparable to the prescribed legal limits stipulated in the current European Union legislation, the method produces acceptably accurate, repeatable, and reproducible results. Trueness, expressed in terms of recovery rates, was demonstrated in most cases by values ranging from 90 to 108. Comparability of results obtained by individual testing laboratories was good (RSDR values <10) for the majority of results. Moreover, HorRat values of <1.1 suggested good performance of the method for all sweeteners and matrixes tested.
Development of a Carbon Paste Electrode Containing Benzo-15-Crown-5 for Trace Determination of the Uranyl Ion by Using a Voltammetric Technique
Authors: Agrahari Sunil K , Kumar Sangita D , Srivastava Ashwini K
Published: February 2020

The interaction of macrocyclic compounds like crown ethers and UO22+ has been studied by electrochemical methods. A modified carbon paste electrode incorporating benzo-15-crown-5 (B15C5) was used to evaluate the electron transfer reaction of UO22+ by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Electrochemical impedance studies showed that charge transfer resistance was less for the B15C5-modified electrode than for the plain carbon paste electrode (PCPE). On the basis of these observations, a UO22+-sensitive crown ether chemically modified electrode (CME) for trace analysis was fabricated and investigated in aqueous solutions. It was found that a 5 B15C5CME for UO22+ showed a better voltammetric response than did the PCPE. UO22+ could be quantified at sub-μg/mL levels by differential pulse voltammetry with a detection limit of 0.03 μg/mL. By differential pulse adsorptive stripping voltammetry, UO22+ could be quantified in the working range of 0.002-0.2 μg/mL, with a detection limit of 1.1 μg/L. Simultaneous determination of UO22+, Pb2+, and Cd2+ was possible. The method was successfully applied to the determination of UO22+ in synthetic, as well as real, samples; the results were found to be comparable to those obtained by inductively coupled plasma-atomic emission spectroscopy.
Determination of Low-Level Acrylamide in Drinking Water by Liquid Chromatography/Tandem Mass Spectrometry
Authors: Lucentini Luca , Ferretti Emanuele , Veschetti Enrico , Achene Laura , Turrio-Baldassarri Luigi , Ottaviani Massimo , Bogialli Sara
Published: February 2020

A simple and sensitive liquid chromatographic-tandem mass spectrometric (LC/MS/MS) method has been developed and validated to confirm and quantify acrylamide monomer (AA) in drinking water using [13C3] acrylamide as internal standard (IS). After a preconcentration by solid-phase extraction with spherical activated carbon, analytes were chromatographed on IonPac ICE-AS1 column (9 250 mm) under isocratic conditions using acetonitrilewater0.1 M formic acid (43 + 52 + 5, v/v/v) as the mobile phase. Analysis was achieved using a triple-quadrupole mass analyzer equipped with a turbo ion spray interface. For confirmation and quantification of the analytes, MS data acquisition was performed in the multireaction monitoring mode, selecting 2 precursor ion to product ion transitions for both AA and IS. The method was validated for linearity, sensitivity, accuracy, precision, extraction efficiency, and matrix effect. Linearity in tap water was observed over the concentration range 0.12.0 g/L. Limits of detection and quantification were 0.02 and 0.1 g/L, respectively. Interday and intraday assays were performed across 3 validation levels (0.1, 0.5, and 1.5 g/L). Accuracy (as mean recovery) ranged from 89.3 to 96.2 with relative standard deviation <7.98. Performance characteristics of this LC/MS/MS method make it suitable for regulatory confirmatory analysis of AA in drinking water in compliance with European Union and U.S. Environmental Protection Agency standards.
Development of a Partial Least-Squares Calibration Model for Simultaneous Determination of Elements by Inductively Coupled Plasma-Atomic Emission Spectrometry
Authors: Chaloosi Marzieh , Asadollahi Seyed Azadeh , Khanchi Ali Reza , FirozZare Mahmoud , Mahani Mohamad Khayatzadeh
Published: February 2020

A partial least-squares (PLS) calibration model was developed for simultaneous multicomponent elemental analysis with inductively coupled plasma-atomic emission spectrometry (ICP-AES) in the presence of spectral interference. The best calibration model was obtained using a PLS2 algorithm. Validation was performed with an artificial test set. Multivariate calibration models were constructed using 2 series of synthetic mixtures (Zn, Cu, Fe, and U, V). Accuracy of the method was evaluated with unknown synthetic and real samples.
Conclusions on Measurement Uncertainty in Microbiology
Authors: Forster Lynne I
Published: February 2020

Since its first issue in 1999, testing laboratories wishing to comply with all the requirements of ISO/IEC 17025 have been collecting data for estimating uncertainty of measurement for quantitative determinations. In the microbiological field of testing, some debate has arisen as to whether uncertainty needs to be estimated for each method performed in the laboratory for each type of sample matrix tested. Queries also arise concerning the estimation of uncertainty when plate/membrane filter colony counts are below recommended method counting range limits. A selection of water samples (with low to high contamination) was tested in replicate with the associated uncertainty of measurement being estimated from the analytical results obtained. The analyses performed on the water samples included total coliforms, fecal coliforms, fecal streptococci by membrane filtration, and heterotrophic plate counts by the pour plate technique. For those samples where plate/membrane filter colony counts were 20, uncertainty estimates at a 95 confidence level were very similar for the methods, being estimated as 0.13, 0.14, 0.14, and 0.12, respectively. For those samples where plate/membrane filter colony counts were <20, estimated uncertainty values for each sample showed close agreement with published confidence limits established using a Poisson distribution approach.
On Using a Normal Approximation for the Noncentral t-Distribution in Determining Upper Limits for Future Sample Relative Repeatability and Reproducibility Standard Deviations
Authors: McClure Foster D , Lee Jung K
Published: February 2020

Formulas, based on a normal approximation for the noncentral t-distribution, were developed to compute 100p one-tailed upper limits for future sample relative repeatability and relative reproducibility standard deviations (RSDr, and RSDR,) collaboratively obtained under a completely randomized model. The accuracy of the formulas for obtaining a one-tailed upper limit for the future sample RSDr, was assessed by comparing the computed noncentral t-distribution-based upper limits with the one-tailed upper limits based on a normal approximation for the noncentral t-distribution. The accuracy of the normal approximation formula for obtaining a one-tailed upper limit for a future sample RSDR, was assessed by comparing the formula-based one-tailed upper limits with those obtained in a Monte Carlo simulation study.
Determination of Macrocyclic Lactone Drug Residues in Animal Muscle by Liquid Chromatography/Tandem Mass Spectrometry
Authors: He Limin , Zhao Donghao , Su Yijuan , Liu Yahong , Nie Jianrong , Lian Jin
Published: February 2020

A robust, credible, and practical multiresidue method based on liquid chromatography/tandem/mass spectrometry (LC/MS/MS) was developed for the simultaneous determination of 9 macrocyclic lactone drugs (abamectin B1a, doramectin, erythromycin, ivermectin B1a, josamycin, kitasamycin, roxithromycin, tilmicosin, and tylosin A) in bovine, porcine, chicken, and sheep muscles. The drugs were extracted with acetonitrile, and the extracts were defatted with n-hexane and further cleaned up on a C18 solid-phase extraction cartridge. LC/MS/MS data acquisition was achieved by using the multiple-reaction monitoring (MRM) mode, i.e., 2 transitions, to provide a high degree of sensitivity and repeatability. Matrix-matched standard calibration curves were used to achieve the best accuracy of the method by compensating for the matrix effect. The calibration graphs were linear (r >0.998) from 10 to 1000 ng/mL for erythromycin, josamycin, kitasamycin, roxithromycin, tilmicosin, and tylosin, and from 5 to 250 ng/mL for abamectin, doramectin, and ivermectin. The average recoveries of the 9 drugs were between 64.5 and 105, calculated by using matrix-matched calibration, with relative standard deviation values ranging from 1.6 to 14. The limits of detection were 0.1 g/kg for erythromycin, josamycin, roxithromycin, and tylosin; 0.2 g/kg for tilmicosin and kitasamycin; and 0.5 g/kg for abamectin, doramectin, and ivermectin. For confirmation, the MRM ratios for the 9 drug residues in the samples and the solvent were evaluated and found to be within the ratio criteria set by the guidelines of the European Union.
Gravimetric Determination of Acid Detergent Fiber and Lignin in Feed: Interlaboratory Study
Authors: Möller Jürgen ,   Collaborators:, Arananant J , Boonnayanont K , Danier J , Egert M , Fütö K , Horst H , Hüther L , Janjira; S , Kongchuensin R , Korol W , Kühl J , Losittisak P , Marth-Schill J , Moreira O , Petrova J , Plos S , Prinze; K , Rungrojpanich V , Schönherr J , Siourai R , Skomial J , Titya S
Published: February 2020

On the basis of AOAC Official Method 973.18, a collaborative study was performed to determine fractions of acid detergent fiber (ADF) and lignin (ADL) in animal feed. The study used 6 animal feed and forage samples as blind duplicates and involved 22 participants from 7 countries. The samples analyzed covered a range from 3.5 to 70 ADF and from <1 to 20 ADL. Repeatability standard deviations ranged from 0.27 to 0.95 for ADF and from 0.08 to 0.59 for ADL. The reproducibility standard deviations ranged from 0.56 to 2.44 for ADF and from 0.52 to 2.09 for ADL. Analyzed samples comprised clover and grass silages, soy meal, cattle feed, wheat, and sawdust. The studied method has been published as the EN ISO 13906:2008 standard.
Application of a Stability-Indicating Thin-Layer Chromatographic Method to the Determination of Tenatoprazole in Pharmaceutical Dosage Forms
Authors: Dhaneshwar Sunil R , Bhusari Vidhya K , Mahadik Mahadeo V , Santakumari B
Published: February 2020

A sensitive, selective, precise, and stability-indicating thin-layer chromatographic (TLC) method was developed and validated for the determination of tenatoprazole both as a bulk drug and in formulation. The method uses TLC aluminum plates precoated with Silica Gel 60F-254 as the stationary phase and the solvent system tolueneethyl acetatemethanol (6 4 1, v/v/v). This system gave compact spots for tenatoprazole (Rf value of 0.34 0.02). Tenatoprazole was subjected to acid and alkali hydrolysis, oxidation, and photodegradation. The peaks of the degradation products were well-resolved from that of the pure drug and had significantly different Rf values. Densitometric analysis of tenatoprazole was performed in the absorbance mode at 306 nm. The linear regression analysis data for the calibration plots showed a good linear relationship over the concentration range of 1001500 ng/spot. The mean values of the correlation coefficient, slope, and intercept were 0.9989 1.42, 10.27 0.965, and 4894.2 1.24, respectively. The method was validated for precision, robustness, and recovery. The limit of detection and limit of quantitation were 50 and 100 ng/spot, respectively. Statistical analysis showed that the method is repeatable and selective for estimation of tenatoprazole. Because the method can separate the drug from its degradation products, it can be used to monitor stability.
Synthesis and Characterization of Mercapturic Acid (N-acetyl-L-cysteine)-Aflatoxin B1 Adduct and Its Quantitation in Rat Urine by an Enzyme Immunoassay
Authors: Nayak Sujatha , Tanuja Penmatsa , Sashidhar Rao Beedu
Published: February 2020

A simple and sensitive indirect noncompetitive enzyme immunoassay to quantitate mercapturic acid-aflatoxin B1 (AFB1) adduct in rat urine is reported. A novel procedure was developed for in vitro synthesis of an immunogen, bovine serum albumen-glutathione-aflatoxin B1 (BSA-GSH-AFB1) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride. Sulphydryl group's analysis confirmed the conjugation of SH groups to AFB1. Thin-layer chromatography and spectral analysis (absorption, fluorescence, and Fourier transform infrared) of the conjugates further confirmed the formation of the adducts. Polyclonal antibodies specific to mercapturic acid-AFB1 adduct were produced against BSA-GSH-AFB1. The assay was found to be linear in the range of 100 pg100 ng of the analyte (y ab x). A 50 displacement of BSA-GSH-AFB1 antibodies was achieved at an inhibitory concentration (IC50)of 11.9 ng GSH-AFB1 (r2 0.98) and 1.22 ng N-acetyl-L-cysteine (NAC)-AFB1 (r2 0.98). Spiking 5 g/mL of reference standard to the control rat urine showed a recovery of 98 2. The immunoassay was validated in a rodent model exposed to a single oral dose of 1 mg/kg body mass of pure AFB1. The excretion of NAC-AFB1 adduct was quantitated at the end of 24 h. The concentration of the NAC-AFB1 adduct excreted in urine as determined by the immunoassay was found to be in the range of 3.225.97 g/mg creatinine. The present method may find wide application as a biochemical tool in molecular epidemiological and intervention studies with respect to human exposure to dietary aflatoxins.
Validation of an Alternative Method for Counting Enterobacteriaceae in Foods Based on Accuracy Profile
Authors: Feinberg Max , Sohier Daniele , David Jean-Francois
Published: February 2020

Several years ago, microbiologists developed a harmonized standard for the validation of alternative methods against the reference method, namely International Organization for Standardization (ISO) 16140:2003. Since then a new and better statistical approach known as the accuracy profile concept has been proposed for interpretation of data collected during a validation study. This approach defines acceptability limits that are used to verify that an alternative analytical method can produce results acceptable for a defined analytical objective. This paper demonstrates how the accuracy profile approach can be efficiently applied to any data set collected according to ISO guidelines and how to interpret the final calculations to decide if a method is valid or not. The procedure was applied to data obtained in the validation of a commercial kit for the enumeration of Enterobacteriaceae in foods. A comparison of several statistical outputs derived from application of the accuracy profile demonstrated that this simple numerical method can be applied despite the non-normal distribution of bacterial colony counts.
Chromatographic Fingerprint Analysis of Pycnogenol® Dietary Supplements
Authors: Chen Pei , Song Fenhong , Lin Long-Ze
Published: February 2020

The bark of maritime pine (Pinus pinaster Aiton) has been widely used as a remedy for various degenerative diseases. A standard high-performance liquid chromatographic (HPLC) procedure for Pycnogenol® analysis is a method specified in the United States Pharmacopeia (USP) monograph, which requires measurement of peak areas and identification of four components of the extract: caffeic acid, catechin, ferulic acid, and taxifolin. In this study, a fingerprint analysis using an HPLC method based on the USP monograph has been developed to provide additional qualitative information for the analysis of Pycnogenol-containing dietary supplements (PDS). Twelve commercially available PDS samples were purchased and analyzed along with a standard Pycnogenol extract. Their chromatographic fingerprints were analyzed using principal component analysis. The results showed that two of the samples were not consistent with the standard reference Pycnogenol extract. One contained other active ingredients in addition to Pycnogenol, and the other may have resulted from a quality control issue in manufacturing.
A Rapid Resolution Liquid Chromatographic Method for Fingerprint Analysis of Raw and Processed Caowu (Aconitum kusnezoffii)
Authors: Qiao Yan-Ling , Zhang Ying-Hao , Zhang Wei , Zhang Jin-Lan
Published: February 2020

A sensitive and reliable rapid resolution liquid chromatographic (RRLC) method coupled with diode array detection has been developed for the fingerprint analysis of raw and processed caowu (Aconitum kusnezoffii). The RRLC fingerprints were established with a Zorbax Extend C18 analytical column (4.6 50 mm, 1.8 m) and gradient elution. Analysis run time was <10 min. The method displayed good precision, stability, and repeatability in fingerprint analysis. Characteristic RRLC fingerprints of caowu were generated and used to assess the consistency and differences in the products. Raw and processed caowu from different sources were analyzed under the developed RRLC conditions, yielding contrasting RRLC fingerprints. Comparison of the RRLC fingerprints of processed and raw caowu indicated that the major constituents changed during processing. Meanwhile, a peak area ratio analysis method was applied to assess their chromatographic fingerprints. In characterizing the constituents of caowu, 11 major chromatographic peaks were identified by mass spectrometry and compared with reference standards and reference data. In summary, RRLC fingerprinting is a rapid and useful way to evaluate the quality of raw and processed caowu.
Determination of Dialkyl Phosphates as Breakdown Products of Organophosphorus Insecticides in Fruit Juices by HPTLC with Fluorescence Detection
Authors: Schwack Wolfgang , Zeisler Tatjana , Stiefel Constanze
Published: February 2020

Dialkyl phosphates (DAP) are common degradation products of organophosphorus pesticides that are used as urinary biomarkers for human exposure. An HPTLC method was developed for the quantitative determination of DAP in fruit juices, i.e., dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), diethyl phosphate (DEP), and diethyl thiophosphate (DETP). Dibutyl phosphate (DBP) was used as an internal standard. The method was based on precipitation of fruit acids in the presence of barium chloride and acetonitrile and liquidliquid extraction with acetonitrilediethyl ether. Extracted DAP were derivatized with 1-(bromoacetyl)pyrene (BAP), and the BAP derivatives separated on HPTLC amino plates with dichloromethane as the mobile phase. Densitometry was performed by measurement of fluorescence at 366/>400 nm. The limit of quantification (LOQ) values were between 0.8 and 1.4 ng/zone. Fluorescence enhancement was achieved by dipping the plate into a paraffin oil solution, increasing the sensitivity and resulting in an LOQ of 0.50.6 ng/zone. Repeatabilities with relative standard deviations of 3.5 (n = 5, at 1520 ng/zone) and coefficients of correlation of 0.9999 were highly satisfactory for rapid trace analysis of DAP in the fruit juices by HPTLC. The mean recoveries from apple juice spiked at 0.5 mg/L were 74, 83, 70, and 57 for DMP, DEP, DMTP, and DETP, respectively. If an application volume of 5 L of apple juice extract was applied, the LOQ in apple juice was 300 g/L. However, this can be lowered by application of higher volumes (up to 50 L) or a more concentrated derivatization batch.
Determination of Available Lysine by Planar Chromatography: A Useful Tool for Protein Quality Evaluation in Fish Feed
Authors: Vega Mario , Aranda Mario
Published: February 2020

Due to the essentiality of lysine for fish, its availability is commonly used as a predictor of the protein nutritional quality of fish feed. The objective of this work was to establish a high-throughput analytical method for protein quality control in fish feed through the measurement of available lysine by planar chromatography. Sample was first incubated with 1-fluoro-2,4-dinitrobenzene to obtain the dinitrophenyl-lysine derivative and then hydrolyzed with hydrochloric acid in order to release the derivative from proteins. Chromatography was performed on silica gel 60 F254 HPTLC plates using n-propanol25 ammonia (7 + 3, v/v) as mobile phase. Quantitative analysis was performed by densitometry in the absorbance mode at 360 nm. Calibration showed a polynomial relationship with an R2 of 0.9991 in the range of 25 to 125.0 ng/band. Repeatability relative standard deviation (RSD) and intermediate precision (RSD) in matrix were 0.8 and 3.6, respectively. Recoveries of spiked samples at two levels ranged from 72 to 85 with RSD from 3 to 8. This method provides the salmon feed industry with a reliable, high-throughput, and low-cost means for routine quality control of available lysine.
Improvement in Botanical Standardization of Commercial Freeze-Dried Herbal Extracts by Using the Combination of Antioxidant Capacity and Constituent Marker Concentrations
Authors: Ninfali Paolino , Gennari Lorenzo , Biagiotti Enrica , Cangi Francesca , Mattoli Luisa , Maidecchi Anna
Published: February 2020

Botanical extracts are standardized to 1 marker compounds (MCs). This standardization provides a certain level of quality control, but not complete quality assurance. Thus, industries are looking for other satisfactory systems to improve standardization. This study focuses on the standardization of herbal medicines by combining 2 parameters: the concentration of the MC and antioxidant capacity. Antioxidant capacity was determined with the oxygen radical absorbance capacity (ORAC) method and the concentrations of the MCs, by high-performance liquid chromatography. Total phenols were also determined by the Folin-Ciocolteau method. The ORAC values, expressed as mol Trolox equivalents/100 g (ORAC ), of 12 commercial herbal extracts were related to the ORAC values of the respective pure MCs at the concentrations at which the MCs occur in products (ORAC-MC ). The ORAC values of 11 extracts were higher than those of the respective MCs and the ratios ORAC-MC /ORAC ranged from 0.007 to 0.7, whereas in the case of Olea europaea leaves, the same ratio was 1.36. The ORAC parameters and their ratios, as well as the linear relationship between ORAC-MC and ORAC , are described and discussed as tools for improving the standardization of herbal products and detecting modifications due to herb processing and storage.
Rapid and Selective UV Spectrophotometric Method for the Analysis of Ceftazidime
Authors: de Haro Moreno Andréia , Salgado Hérida Regina Nunes
Published: February 2020

A new UV spectrophotometric method was developed for quantitative evaluation of ceftazidime preparations. The UV detector was set at 255 nm. Beer's law is obeyed in the concentration range of 7.014.0 g/mL. The method was found to be selective, linear, accurate, and precise in the specified ranges. Intra- and interday variability for the method were <2 relative standard deviation. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method. This method was successfully used for quantification of ceftazidime in pure form and in pharmaceutical preparations.
Validation of an HPLC Method for Determination of Pentoxifylline in Human Plasma and Its Application to Pharmacokinetic Study
Authors: Sripalakit Pattana , Saraphanchotiwitthaya Aurasorn
Published: February 2020

An HPLC method suitable for routine determination of pentoxifylline in human plasma has been adapted and validated. Sample preparation was done by solid-phase extraction. Chloramphenicol was used as the internal standard. The linear range was from 15400 ng/mL (r2 = 0.9994), with a limit of quantitation of 15 ng/mL. The limit of detection was found to be 5 ng/mL. The intra- and interday accuracy ranged from 98.0 to 110.2 and the coefficient of variation was not more than 8.8 for both intra- and interday precision. The absolute recoveries of pentoxifylline and chloramphenicol from human plasma were >97. The method was validated with excellent specificity, accuracy, precision, recovery, and stability. The pharmacokinetic study of a generic pentoxifylline 400 mg tablet in healthy Thai male volunteers after a single dose administration was determined by this developed assay.
Development and Validation of a Liquid Chromatographic Method for the Simultaneous Determination of Estradiol, Estriol, Estrone, and Progesterone in Pharmaceutical Preparations
Authors: Wilson Phyllis
Published: February 2020

Progesterone and estrogens are hormones produced in the human body that are essential for regulating many vital functions. The three major estrogens produced by women are estriol, estradiol, and estrone. Progesterone is a naturally occurring hormone in both men and women. Pharmaceuticals containing estrogens alone or estrogens in combination with progesterone are commonly used in therapy. Patients requiring unique combinations of the drugs rely on pharmacies to compound the ingredients. In order to assess the potency of drugs containing combinations of estrogens and progesterone, a method was developed to determine all four ingredients simultaneously. The liquid chromatographic method utilized a Bondapak C18 column with an isocratic mobile phase of acetonitrilewater (50 + 50, v/v) at a flow rate of 1.0 mL/min and temperature of 30C. Under these conditions, the order of elution was estriol, estradiol, and estrone, followed by progesterone. UV detection was at 205 nm to monitor elution of the estrogens, then switched to 270 nm to monitor progesterone. The method was applied to the analysis of pharmacy-compounded drugs containing combinations of the hormones. Validation studies demonstrated that the method is accurate and precise.
Identification of Volatile Compounds in Chrysanthemum morifolium by Microwave Distillation Solid-Phase Microextraction Coupled with GC/MS
Authors: Zhou Tao , Yang Bei , Zhang Haiying , Yu Yingjia , Chen Bin , Chen Yile , Duan Gengli
Published: February 2020

Microwave distillation with concomitant solid-phase microextraction (MD-SPME) coupled with GC/MS was developed for identifying volatile compounds in the dried flowers of Chrysanthemum morifolium (CM). Different experimental parameters, including SPME fiber coating, microwave power, irradiation time, and water volume were optimized. The best results were obtained using carboxen/polydimethylsiloxane fiber with microwave irradiation at 400 W for 3 min and the addition of 1 mL water into 1.0 g sample. The proposed method allowed the isolation, extraction, and concentration of volatile compounds to be completed in a single step. This MD-SPME-GC/MS method has also been compared to the conventional steam distillation method followed by GC/MS for this identification. Thirty-two volatile compounds were identified using the newly developed MD-SPME-GC/MS process. Relative standard deviation values of <9.8 demonstrate good repeatability. In comparison, 27 compounds were identified by traditional steam distillation-GC/MS. Therefore, the proposed MD-SPME-GC/MS method is simple, rapid, and efficient for identifying volatile compounds in CM.
Determination of Organophosphorous Pesticide Phosphamidon in Environmental Water with Luminol Chemiluminescence Detection
Authors: Li Aifang , Liu Xiaoyu , Kong Juan , Hu Haoyu , Sun Linghui , Qian Zhen
Published: February 2020

A novel chemiluminescence method has been developed for the determination of the organophosphorous pesticide phosphamidon in environmental water samples, based on the reaction of phosphamidon with luminolH2O2 in an alkaline medium using sodium dodecyl benzene sulfonate as the enhancer. Under optimum conditions, the increased chemiluminescence intensity was proportional to the concentration of phosphamidon in the range of 0.011.0 g/mL and the detection limit was 0.0038 g/mL (3). The relative standard deviation was <2 for 0.5 g/mL phosphamidon (n = 11). The proposed method was applied to the determination of phosphamidon residue in an environmental water sample with satisfactory results. Further study was focused on the mechanism of phosphamidon, and a possible mechanism was proposed.
Determination of Erythromycin and Tylosin Residues in Honey by LC/MS/MS
Authors: Granja Rodrigo , Nio Alfredo Montes , Zucchetti Roberto , Nio Rosario Montes , Patel Raj , Salerno Alessandro Gonzalez
Published: February 2020

Antibiotics are used in apiculture to protect bees against a variety of brood diseases. As a result of the development of resistance to oxytetracycline, erythromycin and tylosin are increasingly used for the prevention and treatment of these diseases. Therefore, Brazilian authorities have added these antibiotics to the National Regulatory Monitoring Program for the control of residues in honey. An analytical method has been developed for the determination of residues of erythromycin and tylosin in honey. The procedure involves solid-phase extraction of diluted honey samples with Bond Elut cartridges, followed by LC/MS with electrospray positive ionization in the multiple reaction monitoring mode. Two characteristic transitions were monitored for both drugs. Average analyte recoveries of erythromycin and tylosin ranged from 99 to 109 from sets of replicate honey samples fortified with drug concentrations of 5, 10, 15, and 20 g/kg. The method decision limits were determined to be 1.27 and 0.59 g/kg for erythromycin and tylosin, respectively. The detection capabilities were 5 and 5.2 g/kg for erythromycin and tylosin, respectively.
In-House Validation Study of the DuPont Qualicon BAX System Q7 Instrument with the BAX System PCR Assay for Salmonella (Modification of AOAC Official MethodSM 2003.09 and AOAC Research Institute Performance-Tested MethodSM 100201)
Authors: Tice George , Andaloro Bridget , White H Kirk , Bolton Lance , Wang Siqun , Davis Eugene , Wallace Morgan
Published: February 2020

In 2006, DuPont Qualicon introduced the BAX system Q7 instrument for use with its assays. To demonstrate the equivalence of the new and old instruments, a validation study was conducted using the BAX system PCR Assay for Salmonella, AOAC Official MethodSM 2003.09, on three food types. The foods were simultaneously analyzed with the BAX system Q7 instrument and either the U.S. Food and Drug Administration Bacteriological Analytical Manual or the U.S. Department of AgricultureFood Safety and Inspection Service Microbiology Laboratory Guidebook reference method for detecting Salmonella. Comparable performance between the BAX system and the reference methods was observed. Of the 75 paired samples analyzed, 39 samples were positive by both the BAX system and reference methods, and 36 samples were negative by both the BAX system and reference methods, demonstrating 100 correlation. Inclusivity and exclusivity for the BAX system Q7 instrument were also established by testing 50 Salmonella strains and 20 non-Salmonella isolates. All Salmonella strains returned positive results, and all non-Salmonella isolates returned a negative response.
High-Throughput LC/MS/MS Analysis of Ruscogenin and Neoruscogenin in Ruscus aculeatus L.
Authors: Vlase Laurian , Kiss Béla , Balica Georgeta , Tas Mircea , Crisan Gianina , Leucuta Sorin E
Published: February 2020

A new, sensitive LC/MS/MS method was developed for the quantification of ruscogenin and neoruscogenin in hydrolyzed extracts from Ruscus aculeatus L. (Liliaceae). The two sapogenins were separated on a Zorbax SB-C18 column under isocratic conditions. The detection was performed in the multiple reaction monitoring mode using an ion trap mass spectrometer with an electrospray ionization source operated in positive ionization mode. For the quantification of the ruscogenin and neoruscogenin, calibration curves were constructed over the range of 21000 ng/mL. This is the first reported LC/MS/MS method for the simultaneous analysis of ruscogenin and neoruscogenin, and it showed superior sensitivity when compared with other assays described in the literature. The method has been successfully applied to quantify the two sapogenins in aerial (phylloclades) and underground parts (rhizomes, roots) of Ruscus aculeatus L.
Development of a New HPLC Method for the Simultaneous Determination of Ticarcillin and Clavulanic Acid in Pharmaceutical Formulations
Authors: Tsou Tai-Li , Lee Chiu-Wey , Wang Hsian-Jenn , Cheng Ya-Chung , Liu Yu-Tien , Chen Su-Hwei
Published: February 2020

A new HPLC method has been developed and validated for the simultaneous determination of ticarcillin (TIC) and clavulanic acid (CA) in pharmaceutical formulations. The HPLC separation was achieved on a -cyclodextrin column (Cyclobond I, 250 4.6 mm, 5 mm) with methanol16 mM pH 6.0 ammonium acetate buffer (50 + 50, v/v) mobile phase at a flow rate of 0.8 mL/min. Detection was at 220 nm. Validation of the method was performed by evaluating specificity, robustness, accuracy, and precision. The calibration curves were linear in the range of 1100 g/mL for CA and 2200 g/mL for TIC. The LOQs based on the standard regression lines were 0.42 and 1.42 g/mL for CA and TIC, respectively, and the LOD were 0.14 and 0.47 g/mL, respectively. Total recoveries of synthetic mixtures (CA:TIC = 1:10, 1:15, and 1:30) were 99.25100.99 for CA and 99.54100.82 for TIC. Compared with the U.S. Pharmacopeia method, the proposed method has the advantage of a relatively low flow rate and short analysis time. The proposed method was successfully applied for the simultaneous determination of these two drugs in sterilized H2O and 5 dextrose injection solutions.
Validation of iQ-Check E. coli O157:H7 Real-Time PCR Test Kit for Detection of Escherichia coli O157:H7 in Selected Foods
Authors: Lauer Wendy F , Tymciu Sylvie , Sidi Caroline D , Sonigo Pierre
Published: February 2020

iQ-Check E. coli O157:H7 (Bio-Rad Laboratories, Hercules, CA) is a real-time PCR kit for detection of E. coli O157:H7 from selected foods. Specific fluorescent oligonucleotide probes are used to detect target DNA during the amplification, by hybridizing to the amplicons. These fluorescent probes are linked to a fluorophore which fluoresces only when hybridized to the target sequence. Three foods (ground beef, apple cider, fresh spinach) were selected to compare the performance of iQ-Check E. coli O157:H7 to the U.S. Department of Agriculture-Food Safety and Inspection Service Microbiology Laboratory Guidebook (MLG) reference method for ground beef and the U.S. Food and Drug Administration/Bacteriological Analytical Manual reference method for apple cider and fresh spinach. Three protocols were tested in this study: a shortened 8 h primary enrichment in buffered peptone water (BPW), a 24 h enrichment in BPW, and an enrichment in appropriate reference method enrichment broth. The iQ-Check E. coli O157:H7 method was able to identify more true/confirmed positive samples than the reference method. Inclusivity and exclusivity rates of the method were 100. iQ-Check E. coli O157:H7 performed as expected when minor procedural variations were introduced, validating the ruggedness of the method. There was no significant difference observed in performance over the shelf life of the kit.
Effects of DNA Extraction and Purification Methods on Real-Time Quantitative PCR Analysis of Roundup Ready Soybean
Authors: Demeke Tigst , Ratnayaka Indira , Phan Anh
Published: February 2020

The quality of DNA affects the accuracy and repeatability of quantitative PCR results. Different DNA extraction and purification methods were compared for quantification of Roundup Ready (RR) soybean (event 40-3-2) by real-time PCR. DNA was extracted using cetylmethylammonium bromide (CTAB), DNeasy Plant Mini Kit, and Wizard Magnetic DNA purification system for food. CTAB-extracted DNA was also purified using the Zymo (DNA Clean & Concentrator 25 kit), Qtip 100 (Qiagen Genomic-Tip 100/G), and QIAEX II Gel Extraction Kit. The CTAB extraction method provided the largest amount of DNA, and the Zymo purification kit resulted in the highest percentage of DNA recovery. The Abs260/280 and Abs260/230 ratios were less than the expected values for some of the DNA extraction and purification methods used, indicating the presence of substances that could inhibit PCR reactions. Real-time quantitative PCR results were affected by the DNA extraction and purification methods used. Further purification or dilution of the CTAB DNA was required for successful quantification of RR soybean. Less variability of quantitative PCR results was observed among experiments and replications for DNA extracted and/or purified by CTAB, CTAB+Zymo, CTAB+Qtip 100, and DNeasy methods. Correct and repeatable results for real-time PCR quantification of RR soybean were achieved using CTAB DNA purified with Zymo and Qtip 100 methods.
Determination of Six Pesticides in the Medicinal Herb Cordia salicifolia by Matrix Solid-Phase Dispersion and Gas Chromatography/Mass Spectrometry
Authors: De Carvalho Pedro Henrique Viana , De Menezes Prata Vanessa , Alves Pricles Barreto , Navickiene Sandro
Published: February 2020

A simple and effective extraction method based on matrix solid-phase dispersion was developed for acephate, chlorpropham, pyrimicarb, bifenthrin, tetradifon, and phosalone in leaves of the medicinal plant Cordia salicifolia, whose extracts are commercialized in Brazil as diuretic, appetite suppressant, and weight loss products. The determination method was GC/MS with selectedion monitoring. Different parameters of the method were evaluated, such as type of solid phase (C18, alumina, silica gel, and Florisil) and the amount of solid phase and eluent (dichloromethane, ethyl acetate, chloroform, and cyclohexane). The best results were obtained using 0.5 g herb sample, 0.5 g neutral alumina as the dispersant sorbent, 0.5 g C18 as the cleanup sorbent, and cyclohexanedichloromethane (3 + 1, v/v) as the eluting solvent. The method was validated using herb samples fortified with pesticides at different concentration levels (0.3, 0.5, and 1.0 mg/kg). Average recoveries (seven replicates) ranged from 67.7 to 129.9, with relative standard deviations between 6.3 and 26. Detection and quantitation limits for the herb ranged from 0.10 to 0.15 and 0.15 to 0.25 mg/kg, respectively.
Flame Atomic Absorption Spectrometry Determination of Trace Amount of Cobalt (II) After Preconcentration Using Modified Analcime Zeolite Loaded with bis(2-Hydroxy-1-Naphthaldimine)N-diethylene-triamine
Authors: Shamspur Tayebeh , Mostafavi Ali
Published: February 2020

A simple and sensitive flame atomic absorption spectrometry technique was developed for the determination of trace amounts of cobalt (Co) in various samples after adsorption on modified analcime using a recently synthesized tetradentate Schiff base ligand, bis(2-hydroxy-1-naphthaldimine)N-diethylene-triamine, by a column method in the pH range of 5 to 7, with a flow rate of 1 mL/min. The influence of flow rates of the stripping and sample solution, the amount of ligand, types of stripping, and the least amount of eluent required for elution of the Co ion from the column were investigated. The effects of interfering ions on the recovery of Co were studied. The method was successfully applied for determination of Co in water and plant samples. The maximum capacity of the modified sorbent was found to be 0.58 mg/g of Co(II); the preconcentration factor was 250. Linearity was maintained at 0.240 g/L in the original solution. The LOD was 1.44 102 g/L in the original solution.