scholarly journals Concurrent Determination of Four Fluoroquinolones in Catfish, Shrimp, and Salmon by Liquid Chromatography with Fluorescence Detection

2002 ◽  
Vol 85 (6) ◽  
pp. 1293-1301 ◽  
Author(s):  
José E Roybal ◽  
Calvin C Walker ◽  
Allen P Pfenning ◽  
Sherri B Turnipseed ◽  
Joseph M Storey ◽  
...  
Keyword(s):  
Fluorescence Detection ◽  
Solid Phase ◽  
Fish Tissue ◽  
Extraction Column ◽  
Target Level ◽  
Isocratic Elution ◽  
Standard Curve ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method with fluorescence detection was developed for concurrent determination of 4 fluoroquinolones: ciprofloxacin (CIPRO), enrofloxacin (ENRO), sarafloxacin (SARA), and difloxacin (DIFLX) in catfish, shrimp, and salmon. The procedure consists of extraction from fish tissue with acidified ethanol, isolation and retention on a cation exchange solid-phase extraction column, elution with basic methanol, and LC analysis with fluorescence detection. LC is performed by isocratic elution with acetonitrile–2% acetic acid (16 + 84) mobile phase, and a PLRP-S polymer column with fluorescence detection, excitation 278 nm and emission 450 nm. A target level of 20 ppb for each of the 4 fluoroquinolones has been established for this method. Fortified and incurred fish sample results are based on a 5-point standard curve calculation (10–160 ppb). Overall percent recoveries (% relative standard deviation) from fortified catfish were 78 (10), 80 (11), 70 (9.4), and 78 (10); from fortified shrimp, 69 (5.9), 85 (4.9), 79 (5.9), and 90 (4.5); and from fortified salmon, 56 (15), 93 (5.6), 61 (11), and 87 (5.0) for CIPRO, ENRO, SARA, and DIFLX, respectively. Data from the analysis of fluoroquinolone-incurred catfish, shrimp, and salmon are presented.

scholarly journals Determination of Four Fluoroquinolones in Milk by Liquid Chromatography

1997 ◽  
Vol 80 (5) ◽  
pp. 982-987 ◽  
Author(s):  
José E Roybal ◽  
Allen P Pfenning ◽  
Sherri B Turnipseed ◽  
Calvin C Walker ◽  
Jeffrey A Hurlbut
Keyword(s):  
Fluorescence Detection ◽  
Solid Phase ◽  
Raw Milk ◽  
Extraction Column ◽  
Isocratic Elution ◽  
Standard Curve ◽  
Milk Samples ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method with fluorescence detection is presented for the analysis of 4 fluoroquinolones; enrofloxacin (ENRO), ciprofloxacin (CIPRO), sarafloxacin (SARA), and difloxacin (DIFLX) in milk. The procedure consists of extraction of milk with acidified ethanol, isolation and retention on a cation exchange solid-phase extraction column, elution with basic methanol, and LC analysis with fluorescence detection. LC analysis is performed by isocratic elution using an acetonitrile-2% acetic acid (15 + 85) mobile phase and an Inertsil phenyl column with fluorescence detection at excitation and emission wavelengths of 278 and 450 nm, respectively. A target level of 10 ppb for each of the 4 fluoroquinolones has been established for this method. Average recovery from fortified raw milk samples (5-100 ppb each) based on a 5-point standard curve calculation was 70-90%, with relative standard deviations of <15%.

scholarly journals Determination of Residues of Azamethiphos in Salmon Tissue by Liquid Chromatography with Fluorescence Detection

1999 ◽  
Vol 82 (5) ◽  
pp. 1224-1228 ◽  
Author(s):  
Allen P Pfenning ◽  
José E Roybal ◽  
Sherri B Turnipseed ◽  
Steve A Gonzales ◽  
Jeffrey A Hurlbut
Keyword(s):  
Fluorescence Detection ◽  
Mobile Phase ◽  
Anhydrous Sodium Sulfate ◽  
Solid Phase ◽  
Target Level ◽  
Method Detection Limit ◽  
Standard Curve ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method with fluorescence detection (FLD) is described for determining residues of the pesticide azamethiphos (AZA) in salmon tissue. The sample is extracted with ethyl acetate, centrifuged, dehydrated with anhydrous sodium sulfate, evaporated, reconstituted in water, and defatted with hexane. The aqueous phase is passed through a C18 solid-phase extraction (SPE) column. The SPE column is eluted with methanol, and the eluate is evaporated to dryness and then taken up in 10% acetonitrile (ACN) in water. The analyte is determined by LC using a C18 column, ACN-H2O (32 + 68) mobile phase, and FLD with excitation at 230 nm and emission at 345 nm. Composited salmon tissues were fortified with AZA at 5,10,21, 42, and 83 ng/g or ppb (target level, X = 10 ng/g). Overall recoveries were 86%, with between-day variability of 5.3%. The method detection limit was calculated as 1.2 ppb AZA based on a 5 g sample. The limit of quantitation as determined empirically by this method is the lower limit of the standard curve, approximately 5 ppb.

scholarly journals Determination of Thiabendazole in Orange Juice and Rind by Liquid Chromatography with Fluorescence Detection and Confirmation by Gas Chromatography/Mass Spectrometry After Extraction by Matrix Solid-Phase Dispersion

2004 ◽  
Vol 87 (3) ◽  
pp. 664-670 ◽  
Author(s):  
Beatriz Albero ◽  
Consuelo Sánchez-Brunete ◽  
José L Tadeo
Keyword(s):  
Gas Chromatography ◽  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Orange Juice ◽  
Solid Phase ◽  
Extraction Column ◽  
Matrix Solid Phase Dispersion ◽  
Phase Dispersion ◽  
Relative Standard

Abstract A method was developed for the determination of thiabendazole (TBZ) in orange juice and rind based on matrix solid-phase dispersion (MSPD). TBZ was extracted with ethyl acetate and the extract was subsequently cleaned up on a solid-phase extraction column. Fungicide residues were determined by liquid chromatography with fluorescence detection. Recoveries through the method ranged from 87 to 97% with relative standard deviations ≤11%. The detection and quantitation limits were 0.15 and 0.50 μg/kg, respectively. The confirmation of TBZ residues in positive samples was performed by solid-phase microextraction followed by gas chromatography with mass spectrometric detection using selected ion monitoring. The developed method was applied to determine TBZ levels in commercial orange juices and in juice and rind of fresh oranges. The influence of storage and washing of fruits on TBZ residues was also studied.

scholarly journals Rapid Method for the Determination and Confirmation of Fluoroquinolone Residues in Catfish Using Liquid Chromatography/Fluorescence Detection and Liquid Chromatography-Tandem Mass Spectrometry

2009 ◽  
Vol 92 (4) ◽  
pp. 1233-1240 ◽  
Author(s):  
Sarah E McMullen ◽  
Frank J Schenck ◽  
Victor A Vega
Keyword(s):  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Solid Phase ◽  
Fish Tissue ◽  
Target Level ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Dispersive Spe ◽  
Spe Method

Abstract A simplified method for the extraction and determination of four fluoroquinolone (FQ) residues (ciprofloxacin, enrofloxacin, sarafloxacin, and difloxacin) in catfish is presented. In this method, the FQ residues were extracted with acidified acetonitrile, and the extract was defatted with dispersive C18 solid-phase extraction (SPE) sorbent or hexane. A portion of the extract was evaporated and reconstituted in the mobile phase. The quantitative determination was accomplished with LC-fluorescence detection (FLD), and the confirmation was by LC-MS/MS. Fortifications of catfish tissue were carried out at 0.5x, x, 2x, and 4x, where x = 5 ppb (U.S. Food and Drug Administration current regulatory target level). Recoveries for the LC/FLD determination of five replicates (for both cleanup routes) at each level ranged from 64 to 98, with RSD values <8. The method quantitation limits for all residues were <1 ng/g. The LC-MS/MS analysis of the same extracts confirmed all FQ residues at all levels. This method is an improvement over existing methodologies since additional cleanup steps, such as cation exchange SPE column cleanup, are not utilized. The C18 dispersive SPE method represents a novel cleanup approach for FQs in fish tissue.

scholarly journals Multiresidue Determination of Eleven Quinolones in Milk by Liquid Chromatography with Fluorescence Detection

2005 ◽  
Vol 88 (6) ◽  
pp. 1688-1694 ◽  
Author(s):  
Guixiang Yang ◽  
Baoyin Lin ◽  
Zhenling Zeng ◽  
Zhangliu Chen ◽  
Xianhui Huang
Keyword(s):  
Fluorescence Detection ◽  
Solid Phase ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Phase Gradient ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Multiresidue Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method with fluorescence detection was developed for simultaneous determination of norfloxacin, ofloxacin, ciprofloxacin, pefloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, and flumequine in milk. The samples were extracted with 10% trichloroacetic acid/acetonitrile (9 + 1, v/v) and cleaned by Strata-X reversed-phase solid-phase extraction cartridges. The 11 quinolones were separated on a reversed-phase C18 column (Hypersil BDS-C18) with mobile phase gradient elution and detected with fluorescence by means of a wavelength program. The recoveries for milk fortified with the 11 quinolones at 3 levels were 69–88%, with acceptable relative standard deviations of <9% (intraday) and <14% (interday). The limits of detection were 23 μg/L for enrofloxacin, and 1–9 μg/L for the other 10 quinolones.

scholarly journals Determination of Thiabendazole Residues in Whole Citrus Fruits by Liquid Chromatography with Fluorescence Detection

1996 ◽  
Vol 79 (2) ◽  
pp. 579-582 ◽  
Author(s):  
Rene V Arenas ◽  
Hafizur Rahman ◽  
Nelson A Johnson
Keyword(s):  
Fluorescence Detection ◽  
Solid Phase ◽  
Citrus Fruit ◽  
Extraction Column ◽  
Phase Extraction ◽  
Citrus Fruits ◽  
Average Recovery ◽  
Liquid Chromatographic ◽  
Sensitive Method

Abstract An existing liquid chromatographic (LC) methodfor determination of thiabendazole (TBZ) residues inor on whole green bananas and potatoes was applied to whole, unwashed citrus fruits. The method is applicable for determining TBZ residues in whole oranges,grapefruits, tangerines, and lemons. TBZ is extracted from citrus homogenate with ethyl acetate, and theextract is cleaned up on a cation-exchange, solid-phase extraction column. The purified extract is analyzed by LC with a cation-ex change column and fluorescence detection. Average recovery of TBZ from whole citrus fruits fortified with TBZ at 0.05-20 ppm was 96%. The assay provides a simple, rapid, and sensitive method for monitoring TBZ residues in whole citrus fruit.

scholarly journals Solid-Phase Extraction Cleanup and Liquid Chromatography with Ultraviolet Detection of Ephedrine Alkaloids in Herbal Products

1998 ◽  
Vol 81 (6) ◽  
pp. 1121-1127 ◽  
Author(s):  
Jeffrey A Hurlbut ◽  
Justin R Carr ◽  
Emma R Singleton ◽  
Kent C Faul ◽  
Mark R Madson ◽  
...  
Keyword(s):  
Solid Phase Extraction ◽  
Solid Phase ◽  
Phase Extraction ◽  
Isocratic Elution ◽  
Herbal Products ◽  
Ultraviolet Detection ◽  
Relative Standard ◽  
Triethyl Amine ◽  
Label Claim ◽  
Liquid Chromatographic

Abstract A solid-phase extraction (SPE) cleanup and a liquid chromatographic (LC) method with UV detection is presented for analysis of up to 7 ephedrine alkaloids in herbal products. Alkaloids from herbal products are extracted with acidified buffer, isolated on a propylsulfonic acid SPE column, eluted with a high-ionic-strength buffer, and separated by LC with detection at 255 nm. LC separation is performed by isocratic elution on a YMC phenyl column with 0.1 M sodium acetate-acetic acid (pH = 4.8) containing triethyl-amine and 2% acetonitrile. Ephedrine alkaloids are completely separated in 15 min. Average recovery of 5 common alkaloids from 3 spiked matrixes is 90%, with an average relative standard deviation (RSD) of 4.4% for alkaloid spikes between 0.5 and 16 mg/g. Average quantitation of ephedrine and pseudoephedrine from 6 herbal products is 97% of declared label claims, and average quantitation of synephrine from an herbal dietary product is 85% of label claim (RSD, 3.2%). Recoveries of synephrine, norephedrine, ephedrine, pseudoephedrine, N-methylephedrine, and N-methylpseudoephedrine spiked in 4 herbal products averaged 95%. Results of ruggedness testing and of a second laboratory validation of the procedure are also presented.

scholarly journals Liquid Chromatographic Determination of Acriflavine and Proflavine Residues in Channel Catfish Muscle

1997 ◽  
Vol 80 (3) ◽  
pp. 486-490
Author(s):  
Steven M Plakas ◽  
Kathleen R El Said ◽  
Edward L E Jester ◽  
F Aladar Bencsath ◽  
William L Hayton
Keyword(s):  
Channel Catfish ◽  
Solid Phase ◽  
Water Concentration ◽  
Chromatographic Determination ◽  
Relative Standard ◽  
Waterborne Exposure ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Poor Absorption

Abstract A liquid chromatographic (LC) method was developed for determination of acriflavine (ACR) and proflavine (PRO) residues in channel catfish muscle. Residues were extracted with acidified methanol solution, and extracts were cleaned up with Ci& solid-phase extraction columns. Residue concentrations were determined on an LC cyano column, with spectrophotometric detection at 454 nm. Catfish muscle was individually fortified with ACR (purified from commercial product) and PRO at concentrations of 5,10,20, 40, and 80 ppb (5 replicates per level). Mean recoveries from fortified muscle at each level ranged from 86 to 95%, with relative standard deviations (RSDs) of 2.5 to 5.7%. The method was applied to incurred residues of ACR and PRO in muscle after waterborne exposure of channel catfish to commercial acriflavine (10 ppm total dye for 4 h). RSDs for incurred residues of ACR and PRO were in the same range as those for fortified muscle. Low residue concentrations (<1 % of exposure water concentration) suggested poor absorption of ACR and PRO in catfish.

Determination of Total Taurine in Pet Foods by Liquid Chromatography of the Dansyl Derivative: Collaborative Study

2000 ◽  
Vol 83 (4) ◽  
pp. 784-788 ◽  
Author(s):  
Kieran McCarthy ◽  
Claudia Hischenhuber ◽  
Neil Joyce ◽  
G Cherix ◽  
C Hischenhuber ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Collaborative Study ◽  
Gradient Elution ◽  
Taurine Concentration ◽  
Dansyl Derivative ◽  
Relative Standard ◽  
Standard Deviations ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method for the determination of total taurine in pet foods was evaluated in a collaborative study. Ten laboratories assayed 6 blind duplicate pairs of wet and dry pet foods. The taurine in the 6 sample pairs ranged from low (170 mg/kg) to high (2250 mg/kg) concentrations as is. Collaborators also assayed a sample of known taurine concentration for familiarization purposes. Samples were hydrolyzed to release bound taurine, which was subsequently converted to the dansyl derivative and quantitated by gradient-elution LC with fluorescence detection. Repeatability relative standard deviations, RSDr, ranged from 3.2 to 10.0%; reproducibility relative standard deviations, RSDR, ranged from 6.1 to 16.1%. The method has been adopted Official First Action status by AOAC INTERNATIONAL.

Liquid Chromatographic Determination of Zearalenone and a- and 0-Zearalenols in Milk

1988 ◽  
Vol 71 (6) ◽  
pp. 1176-1179 ◽  
Author(s):  
Peter M Scott ◽  
Guillaume A Lawrence
Keyword(s):  
Methylene Chloride ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Extraction Column ◽  
Hydrophilic Matrix ◽  
Unknown Factor ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract Previous research has demonstrated transmission of zearalenone and α- and β-zearalenols into the milk of cows and other animals. Since human intake of zearalenone and its metabolites via milk is an unknown factor in risk assessment of zearalenone and because appropriate methodology for their determination in milk is not available, a rapid and sensitive analytical method has been developed. Essentially, the method includes extraction with basic acetonitrile, acidification, partition into methylene chloride on a hydrophilic matrix, cleanup on an aminopropyl solid phase extraction column, and reverse- phase liquid chromatography with fluorescence detection. Recoveries from milk averaged 84% for zearalenone, 93% for α-zearalenol, and 90% for β-zearalenol at spiking levels of 0.5 to 20 ng/ mL. As little as 0.2 ng/mL of zearalenone and a-zearalenol and 2 ng/mL of 0-zearalenol can be detected in milk. These 3 compounds are stable in refrigerated milk for at least 2 weeks and in milk brought to boiling. Enzymes (β-glucuronidase and aryl sulfatase) may be added to milk prior to extraction to hydrolyze any conjugates

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