bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Chromatographic Method for Putrescine and Cadaverine in Shrimp
Authors: Rogers Patricia L , Staruszkiewicz Walter F , Benner Ronald A 
Published: February 2020

Abstract
A gas–liquid chromatographic method developed for the determination of putrescine and cadaverine in fishery products was modified for application to the determination of diamines in shrimp. Addition of potassium chloride and hydrochloric acid to the methanol–water extraction solvent resulted in increased recovery of the diamines and minimized gel formation. The recovery of putrescine increased on average from 64 to 98%, and the recovery of cadaverine increased from 85 to 93%. The chromatographic separation of the derivatized diamines was significantly improved with a change from an OV-225 column (cyanopropyl methyl phenyl methyl silicone) to a more polar HP-Innowax column (crosslinked polyethylene glycol). Background levels of putrescine and cadaverine in known high-quality shrimp ranged from 0 to 0.7 ppm. Shrimp that failed sensory examination generally contained putrescine at levels &gt;4.8 ppm and cadaverine at levels &gt;1.3 ppm.
Determination of Pyrethrin and Pyrethroid Pesticides in Urine and Water Matrixes by Liquid Chromatography with Diode Array Detection
Authors: Loper Bobby L , Anderson Kim A 
Published: February 2020

Abstract
The following pyrethrin and pyrethroid pesticides were determined in urine and water matrixes by liquid chromatography with diode array detection (LC–DAD): pyrethrin I, pyrethrin II, tetramethrin, baythroid, bifenthrin, fenvalerate, phenothrin, allethrin, resmethrin, cis-permethrin, and trans-permethrin. In addition, 3-phenoxybenzyl alcohol, a metabolite of various pyrethroids, was also successfully determined by the analytical method. The matrix extraction was simple, inexpensive, and fast, using only sodium chloride and acetonitrile. The acetonitrile extract was filtered and analyzed by LC–DAD. The method detection limits for the pyrethrin pesticides in 5 mL urine were determined to range from 0.002 to 0.04 μg/mL, depending on the individual pyrethrin. Recoveries from spiked tap water ranged from 77 to 96%;recoveries from urine ranged from 80 to 117%. This method is especially well-suited to clinical investigations, in which rapid analysis of forensic samples is often required.
Determination of Ephedrine Alkaloids in Botanicals and Dietary Supplements by HPLC-UV: Collaborative Study
Authors: Roman Mark C ,   Collaborators:, Gray D , Luo G , McClanahan R , Perez R , Roper C , Roscoe V , Shevchuk C , Suen E , Sullivan D , Walther H J 
Published: February 2020

Abstract
An international collaborative study was conducted of a high-performance liquid chromatography (HPLC)-UV method for the determination of the major (ephedrine [EP] and pseudoephedrine [PS]) and minor (norephedrine [NE], norpseudoephedrine [NP], methylephedrine [ME], and methylpseudoephedrine [MP]) alkaloids in selected dietary supplements representative of the commercially available products. Ten collaborating laboratories determined the ephedrine-type alkaloid content in 8 blind replicate samples. Five products contained ephedra ground herb or ephedra extract. These 5 products included ground botanical raw material of Ephedra sinica, a common powdered extract of Ephedra sinica, a finished product containing only Ephedra sinica ground botanical raw material, a complex multicomponent dietary supplement containing Ma Huang, and a high-protein chocolate flavored drink mix containing Ma Huang extract. In addition, collaborating laboratories received a negative control and negative control spiked with ephedrine alkaloids at high and low levels for recovery studies. Test extracts were treated to solid-phase extraction using a strong-cation exchange column to help remove interferences. The HPLC analyses were performed on a polar-embedded phenyl column using UV detection at 210 nm. Repeatability relative standard deviations (RSD r) ranged from 0.64–3.0% for EP and 2.0–6.6% for PS, excluding the high protein drink mix. Reproducibility relative standard deviations (RSD R) ranged from 2.1–6.6% for EP and 9.0–11.4% for PS, excluding the high protein drink mix. Recoveries ranged from 84.7–87.2% for EP and 84.6–98.2% for PS. The data developed for the minor alkaloids are more variable with generally unsatisfactory HORRATS (i.e., &gt;2). However, since these alkaloids generally add little to the total alkaloid content of the products, the method gives satisfactory results in measuring total alkaloid content (RSD r 0.85–3.13%; RSDR 2.03–10.97%, HORRAT 0.69–3.23, exclusive of the results from the high protein drink). On the basis of these results, the method is recommended for Official First Action for determination of EP and PS in dietary supplements exclusive of the high protein drinks.
Development and Single-Laboratory Validation of a Reversed-Phase Liquid Chromatography–Electrospray–Tandem Mass Spectrometry Method for Identification and Determination of Acrylamide in Foods
Authors: Calbiani Francesca , Careri Maria , Elviri Lisa , Mangia Alessandro , Zagnon Ingrid 
Published: February 2020

Abstract
A rapid and accurate method using reversed-phase liquid chromatography–tandem mass spectrometry interfaced with electrospray was developed for determination of acrylamide in cooked food samples. A simplified sample treatment procedure using an extraction step with acidified water without cleanup was developed. A C18 column with an aqueous formic acid–methanol mixture as the mobile phase was used under isocratic conditions. The method was validated in-house for robustness, limits of detection (LOD) and quantitation (LOQ), linearity, recovery, and accuracy both on standard and baked-product and potato flour matrixes. Good results in the low ppb level were obtained for LOD (&lt;15 μg/kg) and LOQ (&lt;25 μg/kg) of acrylamide in samples. Excellent linearity (r 2 = 0.999–1.000) was established over 2 orders of magnitude by performing statistical tests. The absence of both constant and proportional systematic errors demonstrated good method accuracy. Excellent results were obtained for intraday repeatability (RSD &lt; 1.5%) and between-day precision (RSD &lt; 5%). Extraction recoveries from food products were calculated in the 97 ± 3–99 ± 2% (n = 6) range with a labeled internal standard (13C3-acrylamide). The applicability of the method to determination of acrylamide in cooked food products was demonstrated.
Liquid Chromatographic Determination of Urea in Water-Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions: Collaborative Study
Authors: Hojjatie Michael M , Abrams Dean E , Parham Thomas M ,   Collaborators:, Balthrop J , Beine R , Dickinson V , Hartshorn J , Herald S , Latimer G , Padmore J , Pleasants S , Riter K , Roser R , Schmunck G , Sensmeier R , Smith V , Taylor L , Volgas G 
Published: February 2020

Abstract
Water soluble urea-formaldehyde (UF) fertilizers, manufactured by complex reaction of urea and form-aldehyde, typically contain varying amounts of unreacted urea. A liquid chromatography method for the analysis of urea in these products, and in aqueous urea solutions, was collaboratively studied. An amine chromatography column was used to separate the unreacted urea from numerous UF reaction products present in these liquid fertilizers. Unreacted urea was determined by using external urea standards with UV detection at 195 nm. The standards and test samples were prepared in the mobile phase of 85% (v/v) acetonitrile in water. Ten laboratories analyzed 5 different UF-based commercial products containing unreacted urea in the range of 6 to 17% by weight, and 5 different concentrations of urea in water equivalent to commercial products of that nature. The aqueous urea solutions contained 2–20% urea (w/w). The range of sR values for the 5 UF-based commercial fertilizers was 0.49–1.02 and the %RSDR was 1.94–6.14. The sR range for the 5 urea solutions was 0.10 to 0.79 and the %RSDR range was 2.54 to 4.88. The average recovery of urea from the aqueous urea solutions was 96–103%. Therefore, this method is capable of monitoring urea nitrogen manufacturers' label claims and total nitrogen claims in those cases where urea is the sole source of plant food nitrogen. Based on the collaborative study data, the authors recommend this method be approved for AOAC Official First Action status.
Simultaneous Determination of Aflatoxins, Ochratoxin A, and Zearalenone in Grains by New Immunoaffinity Column/Liquid Chromatography
Authors: Göbel Roswitha , Lusky Klaus 
Published: February 2020

Abstract
The simultaneous determination of mycotoxins was performed in 3 steps: extraction, cleanup, and detection. For extraction, a mixture of acetonitrile–water (60 + 40, v/v) was proved appropriate. For cleanup, a new Afla-Ochra-Zea immunoaffinity column was used. After derivatization with trifluoroacetic acid, the mycotoxins aflatoxins, ochratoxin A (OTA), and zearalenone (ZEA) were determined simultaneously by liquid chromatography with fluorescence detection. The detection limits in different matrixes after cleanup with the new immunoaffinity column were very low: aflatoxins, 0.002–0.7 μg/kg; OTA, 0.07–0.25 μg/kg; ZEA, 1–3 μg/kg. The limits of determination were: aflatoxins, 0.25 μg/kg; OTA, 0.5 μg/kg; ZEA, 5 μg/kg. The recovery rates for aflatoxins, OTA, and ZEA for rye and rice were between 86 and 93% when a 0.5 g sample matter per immunoaffinity column was used.
Artifactual Oxidation of Cholesterol During the Analysis of Cholesterol Oxidation Products: Protective Effect of Antioxidants
Authors: Guardiola Francesc , Garcia-Cruset Sandra , Bou Ricard , Codony Rafael 
Published: February 2020

Abstract
To study the influence of the addition of various antioxidants and their combinations on the artifactual oxidation of cholesterol during analysis, 2 factorial experiments were performed in duplicate. In the first experiment, 2 amounts of the following antioxidants were assayed: ethylene-diaminetetraacetic acid (EDTA) disodium salt (0 and 1 mg), pyrogallol (0 and 600 μg), and butylated hydroxytoluene (BHT; 0 and 600 μg); in the second, EDTA disodium salt (0 and 1 mg), ascorbyl palmitate (0 and 600 μg), and BHT (0 and 600 μg). Under low oxidative conditions of dim light, evaporation of solvents at low temperatures, and cold saponification in darkness under nitrogen atmosphere, the addition of antioxidants showed no further protective effect. Furthermore, the presence of ascorbyl palmitate significantly increased the formation of cholesterol- 5β,6β-epoxide, and 7β-hydroxycholesterol.
Physiological Aspects of Resistant Starch and in vivo Measurements
Authors: Champ Martine M-J 
Published: February 2020

Abstract
Resistant starch (RS) is the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals. There are a number of RS with different characteristics which may have a different fate in the colon. As a consequence, all RS should not be considered equivalent as far as physiological properties are concerned; indeed, they may have a different impact on colonic health. This statement may explain part of the apparent contradictions in the literature on RS and cancer or inflammatory disease prevention. RS is fermented in the large intestine into short-chain fatty acids and, among those, butyrate, which is recognized as the main nutrient of the colonocyte. This fermentation pattern seems to be responsible for most of the effects of RS on colonic health. Another important property is linked to its ability to lower colonic pH, which is usually considered as beneficial for mineral biovailability in the colon or cancer prevention. Due to their fate in the digestive tract, RS materials do not seem to have any significant impact on glucose absorption or metabolism. On the contrary, they may have a hypocholesterolemic effect, but available information is contradictory.
Resistant Starch and Colorectal Neoplasia
Authors: Young Graeme P , Le Leu Richard K 
Published: February 2020

Abstract
There are several approaches to examining the relationship between resistant starch (RS) and development of colorectal cancer (CRC). These include examination of epidemiological relationships, objective testing of effects of RS given to humans on biological events of relevance to CRC, and studies in animal models where protection and mechanisms of protection can be directly tested. Nine epidemiological studies have examined the relationship between starch and CRC and/or adenomas. Most show a significant protective effect. However, epidemiological tools for measuring consumption of RS are poorly developed and so a benefit for RS can only be inferred. On balance, the magnitude of protection by starch appears to be in the order of 25–50%. Human intervention studies have examined the effect of various types and amounts of RS consumption on colonic biology. To generalize from these studies, RS softens stools and increases stool bulk, decreases pH, increases short-chain fatty acids (SCFAs) including butyrate, reduces products of protein fermentation, and decreases bile salts in fecal water. Such changes seem to be achieved within about 4 weeks of commencing consumption. The greatest effects are seen with the highest doses where increased fecal starch recovery is observed. A modest number of animal studies have been undertaken. Those examining effects of RS on colonic biology and biomarkers for CRC confirm and extend the results in humans. RS modifies the lumenal environment, largely through altered fermentation of polysaccharides and proteins. RS also affects epithelial biology in that it increases apoptotic deletion of genetically damaged cells. More work is needed to define what types and combinations of RS, perhaps with probiotics, exert the greatest effects on colonic environment and epithelial biology, and then to test these in the cancer models for their protective effect. A few studies have examined effect of RS on cancer as an end point in several rodent models, but the results are not clear cut. In conclusion, consumption of RS dramatically affects the colonic lumenal environment and facilitates apoptotic deletion of genetically damaged cells in the colon, several of which are considered to be biomarkers associated with risk for CRC. These effects can be interpreted as reflecting improved colonic health, which might be of benefit in protection against CRC. Direct evidence for protection is still not available.
New Liquid Chromatographic Method for Determination of Rabeprazole Sodium in Coated Tablets
Authors: Garcia Cássia V , Paim Clésio S , Steppe Martin 
Published: February 2020

Abstract
Rabeprazole sodium is a proton pump inhibitor that covalently binds and inactivates the gastric parietal cell proton pump (H+/K+ ATPase). Little has been published about the quantitative determination of this drug. The aim of this research was to develop a new liquid chromatographic method for quantitative determination of rabeprazole in coated tablets. The system consisted of a Hypersil Keystone Betabasic C8 column (250 × 4.6 mm, 5 μm particle size), an isocratic acetonitrile–water (35 + 65) mobile phase at a flow rate of 1.0 mL/min, and a diode array detector set at 282 nm. The following validation parameters were evaluated: linearity, precision, accuracy, specificity, detection and quantitation limits, and robustness. The method showed good linearity in the concentration range of 10–70 μg/mL. The quantitation limit was 2.43 μg/mL, and the detection limit was 0.80 μg/mL. The intra- and interday precision data showed that the method has good reproducibility (relative standard deviation = 1.03). Accuracy and robustness were also evaluated, and the results were satisfactory. The mean recovery was 101.61%. The analysis of a placebo mixture demonstrated the method is also specific.
A Sensitive Extracto-Photometric Method for Determination of Residual Chlorine in Greywater
Authors: March Juan G , Gual Mateu , Simonet Bartolomé M 
Published: February 2020

Abstract
A new photometric method for chlorine determination based on the oxidative transformation of iodide to iodine and subsequent extraction in ethyl acetate has been developed. The effects of several chemical variables (pH, ionic strength, and iodide concentration) have been studied. Characteristics of the method were linear range 0–0.6 mg Cl2/L, limit of detection 5 μg Cl2/L, and coefficient of variation 0.6%. The method has been applied to greywater without previous sample treatment.
Purity Assessment of Commercially Available Crystalline Deoxynivalenol
Authors: Krska Rudolf , Szente Elisabeth , Freudenschuss Martin , Hametner Christian , Zöllner Peter 
Published: February 2020

Abstract
Deoxynivalenol (DON) obtained from 2 commercial sources was characterized, and its purity was determined. The structural identity of DON was confirmed by 1 Hand 13C-nuclear magnetic resonance (NMR) spectroscopy, gas chromatography with mass spectrometric (GC/MS) detection, and infrared/attenuated total reflectance (IR/ATR) spectroscopy. NMR spectra showed shifts that varied from previously published data. However, we established a complete, unambiguous assignment for all signals. Chromatograms obtained by GC/MS were almost identical for both investigated samples and confirmed the structure of DON. Likewise, IR/ATR spectra verified the identity of DON. The degree of purity was determined by liquid chromatography (LC) with a variable wavelength detector, LC/MS/MS, GC with electron-capture detection (GC-ECD), and ultraviolet (UV) spectrophotometry. The purity check using LC showed a single peak in both chromatograms. With LC/MS/MS measurements, we could detect small amounts of impurities in the crystalline DON from both sources. In data obtained by GC-ECD, no differences in purity were observed. The UV measurements showed an absorption maximum at 217 nm. The mean εm of the extinction coefficients was calculated as 6727 (L/cm/mol) for DON (Sigma) and 6825 (L/cm/mol) for DON (Biopure). Finally, the purity of DON from the 2 commercial sources was calculated as &gt;96 and &gt;98%, respectively. Although the DON produced by both providers can be considered sufficiently pure for routine analysis of trichothecenes in food and feed, this work again demonstrated that the impurity of the solid mycotoxin constitutes the greatest contribution to the overall uncertainty of a mycotoxin calibrant.
Automatic Flow Procedure for the Determination of Ethanol in Wine Exploiting Multicommutation and Enzymatic Reaction with Detection by Chemiluminescence
Authors: Fernandes Elizabeth N , Reis Boaventura F 
Published: February 2020

Abstract
An automatic procedure for the determination of ethanol in wines using a flow system based on multicommutation and enzymatic reaction is described. Alcohol oxidase was immobilized on aminopropyl glass beads and packed in an acrylic column. The peroxide due to enzymatic reaction with ethanol reacted with luminol and generated the chemiluminescence radiation that was monitored by using a laboratory-made detector based on photodiodes. The system manifold comprised a set of 3-way solenoid valves controlled by a microcomputer furnished with electronic interfaces, which ran on software written in Quick BASIC 4.5 to provide facilities to perform on-line sample dilution, reagent addition, and data acquisition. After system parameters optimization, ethanol samples were processed without prior pretreatment. The following suitable features were achieved: linear response ranging from 2.5 to 25% (v/v) ethanol, relative standard deviation of 1.8% (n = 10), detection limit of 0.3% (v/v) ethanol, sampling rate of 23 determinations per hour, and low reagent consumption of 0.23 mg luminol and 7 mg hexacyanoferrate (III) per determination. When the results were compared with those obtained using the AOAC Official Method, no significant difference at the 90% confidence level was observed.
Liquid Chromatographic Determination of St. John's Wort Components in Functional Foods
Authors: Jager Lowri S De , Perfetti Gracia A , Diachenko Gregory W 
Published: February 2020

Abstract
A method was developed for determination of St. John's wort marker compounds hypericin, pseudohypericin, hyperforin, and adhyperforin in functional foods. Solid-phase extraction provided analyte extraction and significant sample cleanup prior to analysis using liquid chromatography (LC) with UV and fluorescence detection. In addition to quantification using LC-UV, confirmation was made with electrospray ionization LC mass spectrometry (LC/MS). Several commercially available tea and drink products claiming to contain St. John's wort were tested. Recoveries ranged from 51 to 98% for the liquid samples. Comparison of the concentrations in 4 St. John's wort teas showed a variation in analyte concentration (1044–10 ng/mL marker compounds in brewed tea) and composition. No marker compounds were found in the beverages, indicating possible decomposition of the marker compounds caused by low pH and/or exposure to light. A solvent extraction procedure was developed for analysis of the marker compounds from solid samples. Analytes were detected at low. parts per million, with an average recovery of 75% No St. John's wort components were found in the 2 solid functional food samples analyzed.
Simultaneous Quantification of Some Pharmaceutical Catharanthus roseus Leaf and Root Terpenoid Indole Alkaloids and Their Precursors in Single Runs by Reversed-Phase Liquid Chromatography
Authors: Digvijay Singh , Shashi Pandey-Rai , Suchi Srivastava , Kumar Rai Sanjay , Raghavendra Mishra , Sushil Kumar 
Published: February 2020

Abstract
A new, rapid, sensitive, and reproducible reversed-phase liquid chromatographic (LC) method with photodiode array detection is described. It allows, in a single run of 30 min, simultaneous separation of 6 pharmaceutically and biologically important Catharanthus roseus leaf and root terpenoid indole alkaloids (TIAs) and 3 of their precursors: TIA precursors tryptophan, tryptamine, and loganine; and TIAs serpentine, catharanthine, ajmalicine, vincristine, vinblastine, and vindoline. The method involves the use of a Phenomenex Luna 5 μm, C18 column (250 mm × 4.6 mm id) and a linear binary gradient mobile phase profile. Detection is performed at 220 and 254 nm, which provided good absorptivity for all of the roseus compounds listed above and gave a minimum detection limit of 0.02 μg/mL. The extraction efficiency, peak purity, and homogeneity parameters of the profiles could be validated using a photodiode array detector. The method was successfully used to quantify major components of leaf and root extracts of C. roseus accessions. The new method thus provides a reliable tool for rapid screening of C. roseus samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments and for monitoring the reaction products, in the in vitro/in vivo conversions of precursors into products, and vice versa.