bluuebunny/crossref_metadata_2025 huggingface dataset:
Interlaboratory Study of a Multiresidue Gas Chromatographic Method for Determination of Organochlorine and Pyrethroid Pesticides and Polychlorobiphenyls in Milk, Fish, Eggs, and Beef Fat
Authors: Bordet François , Inthavong Dary , Fremy Jean-Marc ,   Collaborators:, Aspe D , Durand T , Ducher M , Fontayne N , Grignon E , Herbreteau C , Hulot S , Le Bigot C , Marengue E , Martin V , Ranneaud S , Sartre L , Vouillon B
Published: February 2020

An interlaboratory study was conducted to validate a gas chromatographic (GC) method for determination of 21 organochlorine pesticides, 6 pyrethroid pesticides, and 7 polychlorobiphenyl (PCB) congeners in milk, beef fat, fish, and eggs. The method was performed at low contamination levels, which represent relevant contents in food, and is an extension of the European standard (method NF-EN-1528, Parts 1–4). It enlarges the applicable scope of the reference EN method to pyrethroid pesticides and proposes the use of solid-phase extraction (SPE) as a cleanup procedure. Cryogenic extraction was made, and SPE cleanup was performed with 2 successive SPE cartridges: C18 and Florisil®. After injection of the purified extract onto a GC column, residues were measured by electron capture detection. Food samples (liquid milk, beef fat, mixed fish, and mixed eggs) were prepared, tested for homogeneity, and sent to 17 laboratories in France. Test portions were spiked with 27 pesticides and 7 PCBs at levels from 26 to 45, 4 to 27, 31 to 67, and 19 to 127 ng/g into milk, eggs, fish, and fat, respectively. Based on results for spiked samples, the relative standard deviation for repeatability ranged from 1.5 to 6.8% in milk, 3 to 39% in eggs, 4.5 to 12.2% in fish, and 7 to 13% in fat. The relative standard deviation for reproducibility ranged from 33 to 50% in milk, 29 to 59% in eggs, 31 to 57% in fish, and 30 to 62% in fat. This method showed acceptable intra- and interlaboratory precision data, as corroborated by HORRAT values at low levels of pesticide and PCB contamination. The statistical evaluation of the results was performed according to the International Organization for Standardization (ISO; ISO 3534 standard) and 5725-2 Guideline.
Application of Thermal Desorption to the Development of a Gas Chromatographic/Mass Spectrometric Method for the Determination of Toluene, Chlorinated Aromatic Hydrocarbons, and 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Combustion Emissions
Authors: Donaldson John D , Grimes Susan M , Mehta Lina , Jafari Ahmad J
Published: February 2020

A fast and accurate analytical method, which uses commercially available adsorbents (Tenax TA, Carbotrap B and C, and Carbosieve S-III), was developed for the sampling and determination of aromatic hydrocarbons, chloroaromatic compounds, and 2,3,7,8-tetrachlorodibenzo-p-dioxin. The breakthrough volume data show that Carbotrap C has a good capacity for compounds of high molecular weight, whereas Carbosieve S-III and Tenax TA are efficient for volatile compounds. The organic components are thermally desorbed and transferred to a gas chromatograph/mass spectrometer. Importantly, thermal desorption avoids conventional solvent extraction procedures and also allows reuse of adsorbent tubes. Preliminary results for recovery of analytes from tubes packed with single adsorbent prove that a single-adsorbent bed is not capable of sampling a wide range of compounds. The best method to obtain the desired collection and desorption properties is to use adsorbent tubes containing several different materials. The results of optimization studies are summarized.
Determination of Percentage of RoundUp Ready® Soya in Soya Flour Using Real-Time Polymerase Chain Reaction: Interlaboratory Study
Authors: Hird Heather , Powell Joanne , Johnson Mari-Louise , Oehlschlager Sarah ,   Collaborators:, Anklam E , Buchno M , Bulkmans C , van Duijn G , Foth M , Gachet E , Garrett S , Harris N , Lake R , Moebes A , Moreno C , Popping B , Rentsch J , Sang K , Taesan K , Wiseman G
Published: February 2020

An interlaboratory study was conducted to evaluate a method for determination of the percentage of RoundUp Ready® (RR) soya in soya flour using Taqman® technology. The method included DNA extraction from the test portion with cetyltrimethylammonium bromide buffer followed by chloroform extraction and Wizard® resin cleanup steps. The DNA was then assayed with primer and probe sets specific for lectin as the endogenous control and the RR insert as the target. The percentage of RR soya in the soya fraction of the sample was calculated by using a matrix-matched standard curve. Ten samples of split-level blind duplicates were sent to 22 laboratories in 12 countries worldwide. Test portions contained 0, 0.5, 0.7, 1.6, 2, and 3.9% (w/w) RR soya prepared gravimetrically from commercially available RR standard reference materials. Based on the results for test materials, the relative standard deviation for repeatability (RSDr) for the method ranged from 9.3 to 19.3% and, for reproducibility (RSDR), ranged from 20.3 to 33.7%.
Simultaneous Determination of Zilpaterol and Other Beta Agonists in Calf Eye by Gas Chromatography/Tandem Mass Spectrometry
Authors: Bocca Beatrice , Fiori Maurizio , Cartoni Claudia , Brambilla Gianfranco
Published: February 2020

Adrenergic drugs for growth promotion have been outlawed in European meat production; however, molecules such as Ractopamine and Zilpaterol are licensed for feeding swine and cattle in the United States, Mexico, and South Africa. Analysis of bovine retinal extracts has recently shown considerable extension in the detection period following withdrawal. Previous studies demonstrated that residual concentrations of Clenbuterol and related substances in retinal tissue were >100 ng/g at day 50 of withdrawal. A method was developed to identify and simultaneously quantify Clenbuterol-like substances with anilinic moieties and drugs with phenolic and catecholic moieties, such as Ractopamine and Zilpaterol, in retinal tissue. The method was validated according to SANCO/1805/2000. After extraction in 0.1N HCl, samples were cleaned up on C18 non-endcapped solid-phase extraction columns and analyzed as trimethylchlorosilane derivatives by gas chromatography/tandem mass spectrometry, electron impact mode. At concentrations of agonists between 62.5 and 250.0 ng/g in bovine retina, mean recoveries ranged from 85.3 to 94.8%, repeatability was <9.6%, and within-laboratory reproducibility was <10.5%. The decision limits (CCα) were within the range of 66.3–70.4 ng/g, and the detection capability (CCβ) varied from 73.9 to 79.8 ng/g. Results are discussed in terms of a multiresidue approach to improve reliability of the monitoring strategy.
Determination of Total Fat in Milk- and Soy-Based Infant Formula Powder by Supercritical Fluid Extraction: PVM 2:2002
Authors: LaCroix Denis E , Wolf Wayne R , LaCroix Denis E , Wolf Wayne R , Myer Leslie J D , Calabraro Ron
Published: February 2020

Commercially available simple benchtop systems using CO2 supercritical fluid extraction (SFE) eliminate expensive organic solvent disposal problems and offer potential to meet a demand for rapid, accurate high-volume gravimetric determinations of total fat content of infant formula powders. A Data Quality Objectives (DQOs) approach was used to evaluate the performance characteristics of instrumental SFE extraction for determination of total gravimetric fat in infant formula. The established DQOs included the following: Accuracy.—Correct values were obtained for a suitable reference material, SRM 1846 Infant Formula [National Institute of Standards and Technology (NIST), Gaithersburg, MD]. Ruggedness.—Variables were defined as (1) extraction time (35 min optimum); (2) ratio of sample size to diatomaceous earth support material (1 g sample/2 g support); (3) ratio of distilled water to alcohol (50% isopropanol optimum for both milk- and soy-based infant formula samples); (4) extraction flow rate was 3–3.5 mL/min optimum. Precision.—Relative standard deviations of multiple determinations fell within the Horwitz limits of acceptability of ≤2.8% at the level of analyte determined (0.34–2.5% obtained). Scope of applicability.—Includes milk- and soy-based infant formula powders. Research data were obtained by use of a commercially available fat analyzer. Samples of the SRM, 2 commercial milk-based and 3 commercial soy-based infant formula products were distributed to 2 additional collaborating laboratories. Very good agreement was obtained among the submitting and collaborating laboratories for these samples. The use of clearly defined DQOs to establish method performance characteristics, along with the commercially available reference material, provided the mechanism for verification and validation of analytical methodology.
Concentration of Sodium Ion as the Determining Factor for the Association of Dansyl Amino Acids with the Teicoplanin Molecule in Reversed-Phase Liquid Chromatography
Authors: Ismaili Lhassane , Truong Tong Than , André Claire , Thomassin Mireille , Mozer Jean-Louis , Robert Jean-Francois , Xicluna Alain , Refouvelet Bernard , Millet Joelle , Nicod Laurence , Guillaume Yves-Claude
Published: February 2020

The mechanism of the binding of D,L dansyl amino acids to teicoplanin was investigated. Na+ was used as an indicator of the interactions between the solutes and teicoplanin. The number (n) of sodium ions, Na+, excluded from the soluteteicoplanin interface when analyte transfer occurred was determined. A thermodynamic study and enthalpy–entropy compensation were performed to further explore the interaction mechanism. From these results, it was shown that teicoplanin was balanced between 2 conformational states characterized by distinct enantioselective properties. This approach indicates that liquid chromatography (LC) is a useful tool to extract physicochemical and molecular information from retention data. Thus, LC can be used as a complementary technique with the conventional techniques of molecular interaction analysis.
Determination of Fleroxacin in Pure and Tablet Forms by Liquid Chromatography and Derivative UV-Spectrophotometry
Authors: Kowalczuk Dorota , Hopkała Hanna
Published: February 2020

Derivative UV-spectrophotometric and liquid chromatographic (LC) methods for fleroxacin determination were validated. In the spectrophotometric assay, first-, second-, third-, and fourth-order measurements were applied with the use of peak–zero and peak–peak techniques. The linear correlation between amplitude of the peak and concentration of the examined drug ranged from 2.0 to 12.0 μg/mL. An isocratic LC analysis was performed on a Purospher ODS column with an acidic mobile phase containing tetrabutylammonium hydroxide. Measurements were made at a wavelength of 285 nm with 4-aminobenzoic acid (PABA) as internal standard. The calibration curve was linear (r = 0.9999) in the studied range of concentration (1.0–10.0 μg/mL). The accuracy (mean recovery, about 100%), precision (relative standard deviation <1%), selectivity, and sensitivity of the elaborated methods were satisfactory.
Modification of Enrichment Protocols for TECRA Listeria Visual Immunoassay Method 995.22: Collaborative Study
Authors: Hughes Denise , Dailianis Angela , Duncan Louise , Briggs Julie , McKintyre Deborah A , Silbernagel Karen ,   Collaborators:, Anderson G , Anderson J , Bannach B , Barratt C , Booyens C , Briggs J , Brooks R , Bryant D , Burnie A , Carver C , Chambers D , Chong J , Clarke D , Coates E , Comontofski G , Deiss K , Destro C , Dillon J , Duncan L , Dundas M , Dymond N , Dziedziczak D , Eglezos S , Gasanov U , Gebler J , Graham T , Haley E , Johnson L , Kurien S , Maczuga J , Matera J , Matthew K , Munyard S , Ramine A , Reed J , Remes A , Subasinghe N , Tan A , Tan J , Tatum M , Taylor M , Torrance H , Twohy C , Vialpando M , Watts K
Published: February 2020

A collaborative study was conducted to validate new enrichment methods for the TECRA Listeria Visual Immunoassay (TLVIA). These new methods incorporate a newly formulated medium, TECRA Listeria Enrichment Broth, which does not contain the highly toxic antifungal agent, cycloheximide. The new procedures will provide an alternative to the enrichment procedures described in AOAC Method 995.22. Three food types (raw ground beef, lettuce, and ice cream) were analyzed in the United States, and 2 food types (cooked turkey and cooked fish fillets) were analyzed in Australasia. Thirty collaborators participated in the study, 16 in Australasia and 14 in the United States. With the exception of one batch of ground beef, comparison of the proportion of positive test portions (p ≥ 0.05) showed no significant difference between the TLVIA and the reference method for the 5 foods at 3 inoculation levels. For the one batch of naturally contaminated raw ground beef, the TLVIA gave significantly more confirmed positive results than the reference method.
Determination of Immunoglobulin G in Bovine Colostrum and Milk by Direct Biosensor SPR-Immunoassay
Authors: Indyk Harvey E , Filonzi Enrico L
Published: February 2020

An automated biosensor surface-plasmon resonance-based assay was developed for the determination of immunoglobulin G (IgG) in bovine milk and colostrum with either goat or rabbit antibovine IgG or protein G used as detecting molecule. The method is configured as a direct and nonlabeled immunoassay, with quantitation against an authentic IgG calibrant. Whole colostrum or milk is prepared for analysis by dilution into buffer. Analysis conditions, including ligand immobilization, flowrate, contact time, and regeneration, were optimized, and nonspecific binding was evaluated. Performance parameters included working range of 15–10 000 ng/mL, method detection limit of 0.08 mg/mL, overall instrument response reproducibility relative standard deviation (RSDR) of 0.47%, mean between-run RSDR of 10.5% for colostrum, and surface stability over 200 analyses. The proposed method was compared with independent alternative methods. The technique was applied to the measurement of IgG content during early lactation transition from colostrum to milk, as well as in consumer milk, colostrum, and hyperimmune milk powders.
Comparative Tests To Improve the Gas Chromatographic Analysis of Chlorobornanes in Fish Samples
Authors: Boer Jacob de , Leonards Pim E G , Klungsoyr Jarle , McHugh Brendan , Nixon Eugene , McGovern Evin , Rimkus Gerhard G
Published: February 2020

A comparison was made between electron capture negative ionization quadrupole mass spectrometry (ECNI-MS) and electron capture detection (ECD) with regard to repeatability and reproducibility for the gas chromatographic (GC) analysis of toxaphene congeners [chlorobornanes (CHBs)]. The tests, including standard solutions and several cleaned fish extracts, showed larger relative standard deviations (RSDs) for the repeatability of ECNI-MS but no differences in the reproducibility of the 2 techniques. The sensitivity of the GC-ECNI-MS was considerably better than that of GC/ECD. Four stepwise-designed comparative tests were also conducted on GC analysis, cleanup, and the complete method. The results showed that, according to the current state-of-the-art, coefficients of variation for the between-laboratory performance were not <20% and were usually between 20 and 30%. In spite of separation problems, e.g., for CHB 26, which cannot be separated into a single-component peak, a 95% methyl 5% phenyl polysiloxane (CP Sil 8) column was preferred to more polar columns for the analysis of CHBs 26, 40, 41, 44, 50, and 62. CHB 62 was more difficult to determine than CHB 26 and 50. Addition of the CHBs 40, 41, and 44 to the standard set of 3 chlorobornanes (26, 50, and 62) resulted in more separation problems. A 3-step cleanup method was recommended.
Screening Method for Detecting Cross-Contamination Residues of Tiamulin in Swine Feeds
Authors: Rodríguez-Comesaña Mirian , Cancho-Grande Beatriz , Simal-Gándara Jesús
Published: February 2020

A method was developed for the determination of tiamulin (TML), 14-deoxy-14-[(2-diethylaminoethyl)- mercaptoacetoxy]mutilin hydrogen fumarate, a semisynthetic derivative of the naturally occurring antibiotic pleuromutilin produced by the fungus Pleurotus mutilis. This drug, with high activity against Gram-positive bacteria, some Gram-negative bacteria, and several strains of mycoplasms is administered to animals in food, drinking water, or by injection; however, its chemical structure causes problems in analysis of feeds. Although the molecule is charged below pH 8, at-tempts to analyze TML-containing extracts on ion-exchange columns or other polar stationary phases have failed. Additionally, TML shows no fluorescence activity and only poor UV activity. The present method consists of organic solvent extraction followed by liquid chromatography with UV detection. A low wavelength (208 nm) was used for detection. Limits of detection and quantitation, as well as data for recovery and repeatability obtained during characterization of the method, are described. The applicability of the optimized method was tested by analyzing commercial blank feeds processed after TML-medicated feeds.
Stereo- and Enantioselective Determination of Pesticides in Soil by Using Achiral and Chiral Liquid Chromatography in Combination with Matrix Solid-Phase Dispersion
Authors: Li Zhao-Yang , Zhang Zhi-Chao , Zhou Qi-Lin , Wang Qing-Min , Gao Ru-Yu , Wang Qin-Sun
Published: February 2020

The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose tris-3,5-dimethylphenyl-carbamate as the chiral stationary phase) and a Pirkle-type Chirex 3020 column (urea derivative from the reaction of (R)-1-(α-naphthyl)ethylamine with (S)-tert-leucine, chemically bonded to 3-aminopropylsilanized silica as the chiral stationary phase). The pesticides studied included one organophosphorus insecticide (phenthoate), 3 triazole fungicides (uniconazole, diniconazole, and propiconazole), and 4 pyrethroids (fenpropathrin, β-cypermethrin, β-cyfluthrin, and α-fenvalerate). The enantiomers were separated within 20 min with a resolution of ≥1.5 using a mixture of n-hexane and 2-propanol as the mobile phase for all the pesticides studied except propiconazole, for which only the 2 diastereomers were baseline separated. This method allows determination of the enantiomers or stereoisomers of the above pesticides in soil. The strategy was as follows: (1) First, the total concentration(s) of the enantiomer pair(s) of a chiral pesticide in soil was (were) determined by a newly developed matrix solid-phase dispersion (MSPD) procedure, followed by silica-based LC quantification. The recoveries ranged from 76.5 to 93.6% with relative standard deviations of 6.0%. (2) Second, the enantiomeric ratio(s) (ER(s)) of the chiral pesticide was (were) determined by LC with a chiral stationary phase after fractionation of the MSPD extract by silica-based LC. The determined ERs or stereoisomeric ratio(s) (SR(s); for propiconazole, only the SR of the 2 diastereomers was determined) in soil samples spiked with the above 8 racemic pesticides agreed with those of the corresponding standard solutions. (3) Third, based on the total concentrations and the corresponding ERs, the concentration of each enantiomer in soil was calculated. The proposed method is rapid, precise, and sensitive, and is appropriate for the investigation of the stereo- and enantioselective degradation of pesticides in environmental media.
Determination of Polycyclic Aromatic Hydrocarbons in Honey by Matrix Solid-Phase Dispersion and Gas Chromatography/Mass Spectrometry
Authors: Albero Beatriz , Sánchez-Brunete Consuelo , Tadeo José L
Published: February 2020

A multiresidue method was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in unifloral and multifloral honeys. The analytical procedure is based on the matrix solid-phase dispersion of honey on a mixture of Florisil and anhydrous sodium sulfate in small glass columns and extraction with hexane–ethyl acetate (90 + 10, v/v) with assisted sonication. The PAH residues are determined by gas chromatography with mass spectrometric detection using selected-ion monitoring. Average recoveries for all the PAHs studied were in the range of almost 80 to 101%, with relative standard deviations of 6 to 15%. The limits of detection ranged from 0.04 to 2.9 μg/kg. The simultaneous extraction and cleanup of samples makes this method simple and rapid, with low consumption of organic solvents.
Determination of Sulfathiazole in Type C Medicated Swine Feed by Reversed-Phase Liquid Chromatography with Post-Column Derivatization
Authors: Albert Kendrick , Riter Ken L , Smallidge Robert L
Published: February 2020

A convenient method was developed for determination of sulfathiazole (STZ) in Type C medicated swine feed by reversed-phase liquid chromatography (LC) with post-column derivatization. Addition of extractant solution (0.2N HCl and 1.5% diethylamine in 25% methanol) and an internal standard (IS), sulfamethylthiazole (SMZ), to 5 g sample was followed by mechanical shaking for 1 h. The extract was clarified by chilling, centrifugation, and filtering before injection onto a C18 reversed-phase column. The mobile phase components were 2% acetic acid and 1:1 acetonitrile–methanol (83 + 17%, v/v). Run time was about 20 min. Determination and, largely, the method's selectivity were based on detection at 450 nm of the derivative formed by the post-column reaction of dimethylaminobenzaldehyde with the primary amine of the analyte and IS. The IS, SMZ, differs from STZ by a single substituent methyl group, is stable, and is readily resolved from STZ. Although SMZ is not commercially available, it can be synthesized with relative ease from purchased reagents and will be supplied by the authors to interested laboratories. In single-laboratory validation, linearity was demonstrated over the range of 0.055–550 μg/mL, well beyond the target concentration of 5.5 μg/mL. The estimated limit of detection was 0.04 μg/mL; the calculated limit of quantitation was 0.13 μg/mL (feed concentration of 2.4 g/T or 2.7 mg/kg). Wet-spiking trials with a variety of swine feed matrixes showed recovery to be 100–102% for the intended concentration range, 50–200 g/T, with coefficient of variation (CV) <2%. The method ruggedness was verified with an overall CV of 2.9%.
Validation of Screening Method for Residues of Diethylstilbestrol, Dienestrol, Hexestrol, and Zeranol in Bovine Urine Using Immunoaffinity Chromatography and Gas Chromatography/Mass Spectrometry
Authors: Dickson Leslie C , MacNeil James D , Reid JoAnn , Fesser Adrian C E
Published: February 2020

A method was developed, using commercially available immunoaffinity chromatography cleanup cartridges, followed by detection by gas chromatography/mass spectrometry, to screen for residues of the hormone growth promotants diethylstilbestrol, dienestrol, hexestrol, and zeranol in bovine urine. The single-laboratory, in-house validation included assessment of recoveries, repeatability, linearity of response, detection capability, and specificity (cross-reactivity) with a suite of antibiotics and other hormonal growth promotants. The method was validated for screening at a target concentration of 2.0 μg/L in urine. The detection capabilities for the analytes were diethylstilbestrol, 0.24; dienestrol, 0.15; hexestrol, 0.84; and zeranol, 0.28 μg/L.
Determination of Ephedrine Alkaloids in Human Urine and Plasma by Liquid Chromatography/Tandem Mass Spectrometry: Collaborative Study
Authors: Trujillo William A , Sorenson Wendy R ,   Collaborators:, Gray D , Laurensen J , Luo G , McClanahan R , Perez R , Roper C , Kotello S , Shevchuk C , Suen E , Sullivan D
Published: February 2020

A collaborative study was conducted to evaluate the accuracy and precision of a method for ephedrine-type alkaloids (i.e., norephedrine, norpseudoephedrine, ephedrine, pseudoephedrine, methylephedrine, and methylpseudoephedrine) in human urine and plasma. The amount of ephedrine-type alkaloids present was determined using liquid chromatography (LC) with tandem mass selective detection. The test samples were diluted to reflect a concentration of 5.00–100 ng/mL for each alkaloid. An internal standard was added and the alkaloids were separated using a 5 μm phenyl LC column with an ammonium acetate, glacial acetic acid, acetonitrile, and water mobile phase. Eight blind duplicates of human urine and eight blind duplicates of human plasma were analyzed by 10 collaborators. In addition to negative controls, test portions of urine and plasma were fortified at 3 different levels with each of the 6 ephedrine-type alkaloids at approximately 1, 2, and 5 μg/mL for urine and 100, 200, and 500 ng/mL for plasma. On the basis of the accuracy and precision results for this collaborative study, it is recommended that this method be adopted Official First Action for the determination of 6 different ephedrine-type alkaloids in human urine and plasma.
Determination of Chlorpheniramine Maleate and Tincture Ipecac in Dosage Form by Liquid Chromatography with Ultraviolet Detection
Authors: Eldawy Mohamed A , Mabrouk Mokhtar M , El-Barbary Fawzy A
Published: February 2020

A procedure was developed and validated for measuring chlorpheniramine maleate and tincture ipecac (as emetine hydrochloride) by reversed-phase liquid chromatography with methanol–10mM sodium heptanesulfonate (20 + 30) as the mobile phase; the pH was adjusted to 4 with acetic acid, and the flow rate was at 1.5 mL/min, with ultraviolet detection at 254 nm. Propyl paraben was used as the internal standard. The standard curves were linear (r = 0.998 and 0.9998) for both chlorpheniramine maleate and emetine hydrochlo-ride over the ranges of 5–100 and 0.1–40 μg/mL, respectively. The mean recoveries ± standard deviation were 101.37 ± 2.77% for chlorpheniramine maleate and 98.8 ± 1.47% for emetine hydrochlo-ride. The proposed method was applied to the determination of chlorpheniramine maleate alone in tablet and syrup dosage forms. The method also was applied to the determination of the emetine content of ipecac liquid extract and tincture ipecac; the results were compared with those of the method of the British Pharmacopoeia. The proposed method was applied successfully to the simultaneous determination of chlorpheniramine maleate and tincture ipecac, as emetine hydrochlo-ride, in syrup dosage form. Both drugs and the internal standard were separated from all interfering components in <5 min. The proposed method is simple, specific, and economical, when compared with other published methods that determine each component alone.
Determination of Clopidol Residues in Chicken Tissues by Liquid Chromatography: Collaborative Study
Authors: Pang Guo-Fang , Cao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min , MacNeil James D ,   Collaborators:, Bo H B , Chen J H , Chu X G , Fang X M , Guggisberg D , Gupta R C , Hudecova T , Jia X , Kennedy G , Lin A Q , Lin F , Lin H D , Ling Y C , Ma Z D , Nan Z , One Y , Qin Y , Quiroga M A , Sharman M , Song W B , Soraci A L , Tang F B , Tekel J , Tian M , Uscinas R , Wang F C , Xu H , Zhou L , Zhou W , Zhou X P , Zhu G N
Published: February 2020

Eighteen laboratories participated in a collaborative study on the determination of clopidol residues in chicken muscle tissues by liquid chromatography. Of these, results from 16 laboratories which rigorously followed the method were subjected to statistical analysis. The method performance was assessed by all participants using 14 samples of chicken muscle fortified at concentrations ranging from 0.1 to 5.0 mg/kg. In addition, 9 participants each reported results for 6 clopidol-incurred samples in chicken muscle. Test portions were extracted with acetonitrile, and the extracts were purified with alumina and anion exchange resin solid-phase extraction cartridges in sequence. Clopidol was separated by reversed-phase liquid chromatography and quantified at 270 nm. Average recoveries ranged from 81.8 to 85.4%, reproducibility relative standard deviation (RSDR) ranged from 11.9 to 22.6%, and repeatability relative standard deviation (RSDr) ranged from 9.9 to 15.1%. For clopidol-incurred samples at concentrations of 0.100–0.687 mg/kg, the mean determination value range was 0.099–0.659 mg/kg; RSDR was 12.6–19.8%, RSDr was 3.1–8.5%; and HORRAT values were 0.7–1.1. The accuracy and precision of the method are in conformity with the requirements specified by AOAC INTERNATIONAL. The method was adopted Official First Action in April 2003.
Alternative Liquid Chromatographic Method for Determination of the Methoxyl and 2-Hydroxypropoxyl Content in Cellulose Ether Derivatives
Authors: Rashan Joe , Chen Raymond , Zelesky Todd , Sekulic Sonja
Published: February 2020

An alternative liquid chromatographic (LC) method was developed and validated for the simultaneous determination of methoxyl and 2-hydroxypropoxyl substituents in hypromellose and hypromellose acetate succinate. The method uses the hydriodic acid cleavage reaction, catalyzed by adipic acid, of the substituted methoxyl and 2-hydroxypropoxyl groups, which are quantitatively converted to iodomethane and 2-iodopropane. The iodomethane and 2-iodopropane are extracted into xylene, the extract is diluted with methanol, and the analytes are separated and assayed by gradient elution using a reversed-phase C18 column. The method is selective and sensitive and has good linearity with values of 0.999 for R2 and 0.25% for the y-intercept bias from 1.39 to 5.55 mg/mL for iodomethane, and 0.999 for R2 and 0.52% for the y-intercept bias from 0.184 to 0.735 mg/mL for 2-iodopropane. The relative standard precisions for this LC method were found to be ± 2.3% for determining methoxyl at the 23.1% (w/w) level, and ± 3.5% for determining 2-hydroxypropoxyl at the 6.7% (w/w) level. Compared with the current gas chromatographic (GC) compendial (JPE) method, the LC assay method has equal or better precision. It was found that both the standard and sample solutions have limited stability (8 h) after preparation. This limited stability has not been reported previously in the literature and may have an impact on the reported accuracy/precision of the literature data for the GC method. The LC method was proven to be robust with respect to variation in derivatization time and temperature, flow rate, and column temperature. It is well suited for the quality control needed in today's fast-paced pharmaceutical laboratories.
Receptor Binding Assay for Paralytic Shellfish Poisoning Toxins: Optimization and Interlaboratory Comparison
Authors: Ruberu Shiyamalie R , Liu Yun-Gang , Wong Carolyn T , Perera S Kusum , Langlois Gregg W , Doucette Gregory J , Powell Christine L
Published: February 2020

A receptor binding assay (RBA) for detection of paralytic shellfish poisoning (PSP) toxins was formatted for use in a high throughput detection system using microplate scintillation counting. The RBA technology was transferred from the National Ocean Service, which uses a Wallac TriLux 1450 MicroBeta microplate scintillation counter, to the California Department of Health Services, which uses a Packard TopCount scintillation counter. Due to differences in the detector arrangement between these 2 counters, markedly different counting efficiencies were exhibited, requiring optimization of the RBA protocol for the TopCount instrument. Precision, accuracy, and sensitivity [limit of detection = 0.2 μg saxitoxin (STX) equiv/100 g shellfish tissue] of the modified protocol were equivalent to those of the original protocol. The RBA robustness and adaptability were demonstrated by an interlaboratory study, in which STX concentrations in shellfish generated by the TopCount were consistent with MicroBeta-derived values. Comparison of STX reference standards obtained from the U.S. Food and Drug Administration and the National Research Council, Canada, showed no observable differences. This study confirms the RBA's value as a rapid, high throughput screen prior to testing by the conventional mouse bioassay (MBA) and its suitability for providing an early warning of increasing PSP toxicity when toxin levels are below the MBA limit of detection.
Determination of Fat, Protein, Casein, Total Solids, and Somatic Cell Count in Goat's Milk by Near-Infrared Reflectance Spectroscopy
Authors: Albanell Elena , Caja Gerardo , Such Xavier , Rovai Maristela , Salama Ahmed A K , Casals Ramón
Published: February 2020

Analysis using near-infrared reflectance spectroscopy (NIRS) was investigated as a means of predicting quality parameters of goat's milk. Calibration equations were developed with samples from individual goats of Malagueña and Murciano-Granadina dairy breeds at different stages of lactation to obtain a wide range of variation in milk composition. Prediction equations for milk fat, protein, casein, total solids, and somatic cell count (SCC) were developed with 2 sample presentations, liquid drawer (homogenized milk) and aluminium cup (unhomogenized milk), to measure absorbance values, and accuracy of measurements was compared. The multiple correlation coefficient (R) values for homogenized milk were 0.98, 0.96, 0.91, 0.94, and 0.79 and for unhomogenized milk were 0.98, 0.95, 0.92, 0.95, and 0.74 for fat, protein, casein, total solid, and SCC, respectively. To validate the calibrations, an independent set of samples was used. The best simple correlation coefficient (r) values were 0.97, 0.95, 0.91, 0.93, and 0.72 for homogenized milk and 0.97, 0.95, 0.92, 0.95, and 0.79 for unhomogenized milk. The study showed that NIRS is a useful technique for the prediction of fat, protein, casein, total solids, and SCC in unhomogenized goat's milk.
Salmonella in Foods: New Enrichment Procedure for TECRA Salmonella Visual Immunoassay Using a Single RV(R10) Only, TT Only, or Dual RV(R10) and TT Selective Enrichment Broths (AOAC Official Method 998.09): Collaborative Study
Authors: Hughes Denise , Dailianis Angela E , Hill Louise , Curiale Michael S , Gangar Vidhya ,   Collaborators:, Arnold D , Barrat C , Baxter T , Bell J , Brooks R , Bryant D , Burke K , Burnie A , Cliffard D , Danisavich T , Daniels K , Deiss K , D’Onorio A , Faucher K , Finkenbiner D , Gasanov U , Gebler J , Gerry A , Graham D , Graham T , Harris P , Hetrick S , Jurgens J , Keating K J , Klokman R , Le C , Matrozza M , McCarthy R , McCawley C , Munyard S , Pye V , Rajkowski K , Ristov K , Rosinko J , Schneider K , Schubert M J , Sloan E , Souter  , Wilson M , Zuroski K
Published: February 2020

A collaborative study was conducted to compare a new enrichment procedure for the TECRA® Salmonella Visual Immunoassay (TSVIA) with the reference method given in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (7th Ed.). Three food types (milk powder, pepper, and soy flour) were analyzed in Australia and 3 food types (milk chocolate, dried egg, and raw turkey) were analyzed in the United States. Thirty-eight collaborators participated in the study. The TECRA method was evaluated using both Rappaport-Vassiliadis R10 (RV(R10)) and tetrathionate (TT) broths for selective enrichment. M broth cultures arising from each of the 2 selective enrichment broths were tested in the TSVIA using 2 individual wells, one for each selective broth, and a single well to test the pooled selective enrichment broths. The results for the pooled enrichment broths were reported elsewhere. This study presents the results for the use of single enrichment broths, i.e., RV(R10) only or TT only, with the TSVIA. No significant differences (p > 0.05) were observed for the pairwise comparison of the proportion of positive samples for either RV(R10) or TT used as a single enrichment broth for the TSVIA with that for the reference method.
Amnesic Shellfish Poisoning Toxins in Shellfish: Estimation of Uncertainty of Measurement for a Liquid Chromatography/Tandem Mass Spectrometry Method
Authors: Holland Patrick T , McNabb Paul , Selwood Andrew I , Neil Tracey
Published: February 2020

A liquid chromatography/mass spectrometry (LC/MS) method for amnesic shellfish poisoning toxins in shellfish was developed and validated. Tissue homogenate (4 g) was extracted with 16 mL methanol–water (1 + 1, v/v). Dilution into acetonitrile–water (1 + 9, v/v) was followed by C18 solid-phase extraction cleanup. Domoic acid (DA) and epi-domoic acid were determined by LC/MS/MS with electrospray ionization and multiple reaction monitoring. External calibration was performed with dilutions of a certified reference standard. Advantages of this method include speed, lower detection limits, and a very high degree of specificity. The LC/MS response was highly linear, and there were no significant interferences to the determination of DA. Formal method validation was performed on 4 shellfish species. Fortification studies gave recoveries (mean ± SD; n = 24) of 93 ± 14% at 1 mg/kg, and 93.3 ± 7.6% at 20 mg/kg over all the species. Analysis of a mussel certified reference material showed the bias as <5%. The limits of detection and quantitation were 0.15 and 0.5 mg/kg, respectively. Routine application of the method over 4 months gave a recovery for the QC sample (1 mg/kg fortified blank mussel homogenate) run with each batch of 88.9 ± 5.5% (mean ± SD; n = 37). The total uncertainty of measurement results were estimated as 0.12 (12%) at 0.25–5 mg/kg and 0.079 (7.9%) at 5–50 mg/kg. The major contribution to the uncertainty was the repeatability of the LC/MS determination, probably arising from subtle matrix effects.
Thermoluminescence Detection of Irradiated Fruits and Vegetables: International Interlaboratory Trial
Authors: Sanderson David C W , Carmichael Lorna A , Fisk Saffron ,   Collaborators:, Christensen P , Delincée H , Hammerton K , Nootenboom H , Pfordt J , Pinnioja S , Schreiber G A , Toyoda M
Published: February 2020

An international interlaboratory trial was conducted to validate thermoluminescence methods for detecting irradiated fruits and vegetables. Five products were used in this study. This paper presents the results from prestudy material, homogeneity testing, details of sample preparation, and participants' results. Prestudy results provided a basis for cross comparison of instruments in different laboratories. A wide range of sensitivities, reproducibilities, and signal-to-background ratios were observed. Homogeneity testing showed that the method can distinguish between nonirradiated and irradiated products, including those bleached with 100 J/cm2 artificial daylight, provided that sensitivity rejection criteria are rigorously applied. Blind results were returned by 9 participants in the form of first and second glow integrals and glow ratios for all samples and a qualitative classification for each product. Of the 387 results reported, 327 valid results were obtained from participants. Where valid data were obtained, correct qualitative identifications were made by participants in all cases. Participants' results and homogeneity testing both confirm the validity of the thermoluminescence method for detecting irradiated fruits and vegetables.
Thermoluminescence Detection of Irradiated Shellfish: International Interlaboratory Trial
Authors: Sanderson David C W , Carmichael Lorna A , Fisk Saffron ,   Collaborators:, Christensen P , Delincée H , Nootenboom H , Pfordt J , Pinnioja S , Schreiber G A , Wagner U
Published: February 2020

An international interlaboratory trial was conducted using thermoluminescence for the detection of irradiated shellfish, aimed at validating the method for routine use. Nephrops norvegicus, mussels, brown shrimps, black tiger prawns, and king scallops were presented as nonirradiated and irradiated to 0.5 and 2.5 kGy. The protocol called for the use of 3 preparation methods: extraction of silicates from whole shellfish by acid hydrolysis and physical separation, and of carbonates from powdered shells. Homogeneity was tested on each product and each treatment. Results verified that all methods were able to distinguish between nonirradiated and irradiated samples regardless of dose. Silicate methods produced better discrimination than powdered shell, and acid hydrolysis showed some evidence of better separation between the 2 doses than the physical method. Participants received each product in each treatment category for blind analysis. Six participants returned results for acid hydrolysis, 7 for physical separation, and 5 for the powdered shell method. Their results confirmed the homogeneity testing. Qualitative results gave 100% correct classification for both silicate methods and 85.3% for powdered shell. Silicate methods are therefore preferable unless only shell is available. Overall, the results confirmed the case for validation.
Rapid Impedance Method for Predicting the Potential Shelf Life of Packaged Pasteurized Milk
Authors: Zhiyong Li , Minying Yi , Jianting Gao
Published: February 2020

The potential shelf life of packaged pasteurized milk was studied using a rapid impedance method. The results showed a high correlation between the shelf life of Fengxing and Xiang Man-lou pasteurized milks and between the detection time and the logarithm of colony-forming units per milliliter. The impedance detection time was measured after preliminary incubation at 30°C for 6 h for 100 and 200 μL milk samples, or at 37°C for 6 h for 100–400 μL milk samples for Fengxing pasteurized milk, and after 6 h preliminary incubation at 30°C for 300 and 400 μL milk samples or6hat37°C for 100–400 μL milk samples for Xiang Man-lou pasteurized milk. Regressive equations were then constructed to predict the potential shelf life. Compared with the traditional method, the impedance method plus pre-incubation of milk at elevated temperatures (30 and 37°C) was rapid, accurate, and convenient. The entire estimation process was completed within 11–14 and 14–20 h for Fengxing and Xiang Man-lou pasteurized milks, respectively.
Evaluation of the BAX® System for Detection of Salmonella in Selected Foods: Collaborative Study
Authors: Silbernagel Karen , Jechorek Robert , Carver Charles , Barbour W Mark , Mrozinski Peter ,   Collaborators:, Albert A , Andaloro B , Anderson G , Beacorn F , Brooks R , Carson M , Crossfield D , Eliasberg S , Farmer D , Frantzeskakis C , Gasses T , Gatesy T , Hall G , Hanson P , Heddaeus K , Hermann K , Hutchins J , Jenkins J , Johnson F , Johnson J , Kawalek M , Kelly L , Koschmann C , Lannon P , Lester D , Manner K , Martin J , Maselli M , McGovern B , Mohnke F , Moon B , Murray L , Pace R , Richards J , Robeson S , Rodgers D , Rosario G , Saunders C , Shaw C , Dana Shell J , Sloan E , Thompson S , Vialpando M , Voermans R , Watts K , Wieczorek K , Wilson K , Yeh H , Zamora D
Published: February 2020

A multilaboratory study was conducted to compare the automated BAX® System to the standard cultural methods for detection of Salmonella in selected foods. Five food types—frankfurters, raw ground beef, mozzarella cheese, raw frozen tilapia fish, and orange juice—at 3 inoculation levels, were analyzed by each method. A sixth food type, raw ground chicken, was tested using 3 naturally contaminated lots. A total of 16 laboratories representing government and industry participated. In this study, 1386 samples were analyzed, of which 1188 were paired samples and 198 were unpaired samples. Of the 1188 paired samples, 461 were positive by both methods and 404 were negative by both methods. Thirty-seven samples were positive by the BAX System but negative by the standard reference method, and 11 samples were positive by standard cultural method and negative by the BAX System. Of the 198 unpaired samples, 106 were positive by the BAX System and 60 were positive by the standard cultural method. A Chi square analysis of each of the 6 food types, at the 3 inoculation levels tested, was performed. For all foods, the BAX System demonstrated results comparable to those of the standard reference methods based on the Chi square results.
Determination of Orotic Acid, Uric Acid, and Creatinine in Milk by Liquid Chromatography
Authors: Indy Harvey E , Woollar David C
Published: February 2020

A simultaneous determination of orotic acid, uric acid, and creatinine in milk is described. Following deproteinization, the sample was analyzed by reversed-phase liquid chromatography, using a highly aqueous cationic ion-pair eluent and photodiode array UV detection. In view of their potential dietary significance, the validated method was applied to survey the influence of species, season, and lactation on their contribution to the nonprotein nitrogen pool in milk. Mature bovine milk contained orotic acid, uric acid, and creatinine in the range of 30–70, 9–24, and 6–12 μg/mL, respectively. Although uric acid and creatinine were present in all milks, orotic acid was essentially absent in nonruminant milks. In contrast to urate and creatinine, expression of orotic acid in bovine milk was strongly dependent on stage of early lactation. The co-existence in mammalian milks of related nucleoside and nucleotide components was also determined.
Direct Determination of Free Methionine in Soy-Based Infant Formula
Authors: Johns Paul , Phillips Rosalyn , Dowlat Lobat
Published: February 2020

A method was developed for the direct determination of free methionine in soy-based infant formula, with analyte separation and quantitation by reversed-phase liquid chromatography (LC), and UV absorbance at 214 nm, respectively. Sample preparation required only dilution with mobile phase and syringe filtration. Using a 0.02M KH 2 PO 4 mobile phase (pH adjusted to 2.9 with 85% o-phosphoric acid) and 0.7 mL/min flow rate, methionine eluted at approximately 8 min, and total run time was 14 min after column regeneration with acetonitrile–water. System linearity was demonstrated as peak area versus analyte concentration, ranging from 80 to 120% of the formula specification for free methionine (r > 0.999, and all residuals <0.45%). Intermediate precision relative standard deviation values were <1.5% for ready-to-feed and reconstituted powder samples, and recoveries ranged from 98.0 to 103.5% for inter-method comparison with an amino acid analyzer method. The limit of quantitation was 3 mg methionine/L in the “as fed” infant formula. Despite the relatively weak UV absorptivity of methionine, the 214 nm signal was sufficiently intense in the 30–65 mg/L (201–436 μM) range to afford quantitation by peak area proportionation versus a 2-point external standard calibration. This direct UV detection after reversed-phase LC separation provides a simple and accurate method for determining free methionine without derivatization.
Determination of Clenbuterol, Salbutamol, and Cimaterol in Bovine Retina by Electrospray Ionization–Liquid Chromatography–Tandem Mass Spectrometry
Authors: Lau Joseph H W , Khoo Cheang S , Murby John E
Published: February 2020

An electrospray ionization–liquid chromatography–tandem mass spectrometry (ESI/LC/MS/MS) method was developed for the simultaneous determination of the β-agonists clenbuterol, salbutamol, and cimaterol in bovine retina. The tissue was homogenized in alkaline buffer and spiked to give 10, 15, and 20 ng/g each of the 3 analytes together with the internal standards d6-salbutamol and d6-clenbuterol. The mixture was incubated with protease enzyme to release any protein-bound analytes and then made alkaline before extraction with isobutanol. The extract was dissolved in water and transferred to a clenbuterol immunoaffinity column. After washing, the analytes were eluted and analyzed by ESI/LC/MS/MS using a C18 column with acetic acid–methanol as mobile phase. No interferences were observed from the spiked retina extract at the various single-reaction monitoring modes. Average recoveries for clenbuterol, salbutamol, and cimaterol were 94, 85, and 87% with coefficients of variation (CVs) of 9.4, 9.9, and 8.6%, respectively. A correlation coefficient of r2 = 0.9999 was obtained for all analytes. The limits of detection for clenbuterol, salbutamol, and cimaterol, determined from 3 times the standard deviation of 7 replicates of the lowest spike, were 2.5, 3.5, and 2.0 ng/g with CVs of 8.9, 11.6, and 7.2%, respectively.