Matrix Solid-Phase Dispersion (MSPD) Isolation and Liquid Chromatographic Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk

1990 ◽  
Vol 73 (3) ◽  
pp. 379-384 ◽  
Author(s):  
Austin R Long ◽  
Lily C Hsieh ◽  
Marsha S Malbrouh ◽  
Charles R Short ◽  
Steven A Barker
Keyword(s):  
Solid Phase ◽  
Correlation Coefficients ◽  
Chromatographic Determination ◽  
Average Percentage ◽  
Phase Dispersion ◽  
Fortified Milk ◽  
Photodiode Array ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A multlresldue method for the isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycllne (CTC) antibiotics In milk Is presented. Blank and tetracycline (OTC, TC, and CTC) fortified milk samples (0.5 mL) were blended with octadecylsllyl (C18, 40 /an, 18% load, endcapped, 2 g) derivatized silica packing material containing 0.05 g each of oxalic acid and dlsodlum ethylenedlamlnetetraacetlc. A column made from the C18/milk matrix was first washed with hexane (8 mL), following which the tetracyclines were eluted with ethyl acetate-acetonltrlle (1 + 3; v/v). The eluate contained tetracycline analytes that were free from Interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array, 365 nm). Correlation coefficients of standards curves for Individual tetracycline isolated from fortified samples were linear (from 0.982 ± 0.009 to 0.996 ± 0.004) with average percentage recoveries from 63.5 to 93.3 for the concentration range (100,200,400,800,1600, and 3200 ng/ mL) examined. The Inter-assay variability ranged from 8.5 ± 2.4% to 20.7 ± 13.0% with an Intra-assay variability of 1.0- 9.3%.

scholarly journals Liquid Chromatographic Determination of Five Benzoylurea Insecticides in Fruit and Vegetables

1998 ◽  
Vol 81 (5) ◽  
pp. 1037-1042 ◽  
Author(s):  
Miguel Gamón ◽  
Adolfo Saez ◽  
Rosa Pelegrí ◽  
Inmaculada Peris ◽  
Josá G De La Cuadra ◽  
...  
Keyword(s):  
Solid Phase ◽  
Chromatographic Determination ◽  
Photodiode Array Detection ◽  
Photodiode Array ◽  
Array Detection ◽  
Liquid Chromatographic Determination ◽  
Benzoylurea Insecticides ◽  
Vegetables And Fruits ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method was developed to determine 5 benzoyl ureas—diflubenzuron, hexaflumuron, teflubenzuron, flufenozuron, and lufenuron—in peppers, tomatoes, eggplants, cucumbers, and oranges. Preparation of samples involve extraction with acetone and partitioning into dichloromethane-petroleum ether. A portion of this extract is cleaned up with a solid-phase extraction aminopropyl disposable column. With LC analysis using an RP-8-DB microbore column, acetonitrilewater (70 + 30, v/v) as mobile phase, and photodiode array detection at 254 nm, recovery and repeatability data were collected for the 5 benzoylureas on 4 vegetables and citrus in the range 0.04-2.0 mg/kg. Validated limits of detection and quantitation were 0.01 and 0.04 mg/kg, respectively. The method is reliable for routine analysis of vegetables and fruits

Liquid Chromatographic Determination of Methylene Blue and Its Metabolites in Milk

1992 ◽  
Vol 75 (5) ◽  
pp. 796-800 ◽  
Author(s):  
Robert K Munns ◽  
David C Holland ◽  
José E Roybal ◽  
John G Meyer ◽  
Jeffrey A Hurlbut ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Lactating Cows ◽  
Azure B ◽  
Leuco Form ◽  
Fortified Milk ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A method is described for the liquid chromatographic (LC) determination of trace levels of methylene blue (MB) and its metabolites in milk. The cleanup involves protein precipitation with acetonitrile, extraction into chloroform of MB and its metabolites (azure A [AZA], azure B [AZB], and azure C [AZC]), extraction by chloroform of thionin at pH 10, and solid-phase extraction on a disposable carboxylic acid column. LC separation and quantitation are performed with an isocratic acetonitrile-acetate buffer mobile phase on a cyano column. Average recoveries (5-20 ppb levels) of MB, AZA, AZB, and thionin from fortified milk were 83.2,60.0, 84.4, and 22.5%, respectively. Some incurred MB metabolites in milk are bound organically to a fraction of the milk substrate, whereas others are free demethylated forms of MB. Analysis of milk collected 8 h after administration of MB contained the following average levels (n = 6) of free MB and metabolites: MB, 31.0 ppb; AZA, 21.3 ppb; and AZB, 54.1 ppb. Depletion of free MB and metabolites AZA and AZB from milk after administration of MB to lactating cows occurred in less than 40 h. Metabolites of MB that formed complexes with organic compounds were hydrolyzed in part to the free forms. The leuco form of MB cou

Matrix Solid Phase Dispersion Isolation and Liquid Chromatographic Determination of Five Benzimidazole Anthelmintics in Fortified Beef Liver

1990 ◽  
Vol 73 (6) ◽  
pp. 860-863 ◽  
Author(s):  
Austin R Long ◽  
Marsha S Malbrough ◽  
Lily C Hsieh ◽  
Charles R Short ◽  
Steven A Barker
Keyword(s):  
Solid Phase ◽  
Correlation Coefficients ◽  
Chromatographic Determination ◽  
Activated Alumina ◽  
Beef Liver ◽  
Liquid Chromatographic Determination ◽  
Internal Standardization ◽  
Liquid Chromatographic ◽  
Benzimidazole Anthelmintics

Abstract A multlresidue method for Isolation and liquid chromatographic determination of 5 benzimidazole anthelmintics (thiabendazole, oxfendazole, mebendazole, albendazole, and fenbendazole) in beef liver tissue is presented. Blank or benzlmldazole-fortlfled liver samples (0.5 g) were blended with octadecylsilyl derlvatlzed silica packing material (C18, 18% load, endcapped, 2 g). A column made from the C18/ liver matrix was first washed with hexane (8 ml_), following which the benzlmldazoles were eluted with acetonltrile. The acetonltrlle extract was then passed through an activated alumina column. The eluate contained benzimidazole analytes that were free from Interfering compounds as determined by UV detection (photodlode array, 290 nm). Correlation coefficients of standard curves for Individual benzlmldazoles Isolated from fortified samples, using internal standardization, were linear (0.996 ± 0.002 to 0.999 ± 0.001) with average relative percentage recoveries from 62.0 ± 6.7 to 86.8 ± 8.6% for the concentration range (100- 3200 ng/g) examined. The interassay variability was 7.0 ± 4.1 to 12.9 ± 10.2% with an Intra-assay variability from 2.2 to 4.0%.

Solid-Phase Extraction and Liquid Chromatographic Determination of Monophthalates and Phthalide ExtractedFrom Solution Administration Sets

1993 ◽  
Vol 76 (3) ◽  
pp. 531-534 ◽  
Author(s):  
Robert P Snell
Keyword(s):  
Solid Phase ◽  
Correlation Coefficients ◽  
Chromatographic Determination ◽  
Relative Standard ◽  
Chromatographic Procedure ◽  
Monobutyl Phthalate ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Ethylhexyl Phthalate

Abstract A liquid chromatographic procedure is described for the determination of phthalide, monobutyl phthalate, and mono-2-ethylhexyl phthalate leached by water from solution administration sets. Recoveries varied from 88.8% for phthalide at 1 (μg/50 mL to 113% for monobutyl phthalate at 6 μg/50 mL. Relative standard deviations at 1 μg/50 mL were 2.59% for phthalide, 3.54% for monobutyl phthalate, and 11.6% for mono-2- ethylhexyl phthalate. At 6 μg/50 mL, the relative standard deviation for mono-2-ethylhexyl phthalate decreased to 3.88%. Reproducibilities for 5 standard injections were 1.40% for phthalide, 1.84% for monobutyl phthalate, and 1.95% for mono-2- ethylhexyl phthalate. Correlation coefficients were 1.00 for the 3 compounds. Five sets from 2 manufacturers were examined. No phthalide or monobutyl phthalate was found. One manufacturer’s sets contained 37.6-44.4 μg/L mono-2- ethylhexyl phthalate. The sample matrix had some interference if phthalide or monobutyl phthalate was present.

Multiresidue Method for Isolation and Liquid Chromatographic Determination of Seven Benzimidazole Anthelmintics in Milk

1989 ◽  
Vol 72 (5) ◽  
pp. 739-741 ◽  
Author(s):  
Austin R Long ◽  
Lily C Hsieh ◽  
Marsha S Malbrough ◽  
Charles R Short ◽  
Steven A Barker
Keyword(s):  
Methylene Chloride ◽  
Correlation Coefficients ◽  
Chromatographic Determination ◽  
Multiresidue Method ◽  
Milk Samples ◽  
Photodiode Array ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Benzimidazole Anthelmintics

Abstract A multiresidue method for the isolation and liquid chromatographic determination of 7 benzimidazole anthelmintics (thiabendazole, oxfendazole, para-hydroxyfenbendazole, fenbendazole sulfone, mebendazole, albendazole, and fenbendazole) in milk is presented. Blank or benzimidazole-spiked milk samples (0.5 mL) were blended with octadecylsilyl (C-18, 18% load, end-capped) derivatized silica packing material. A column made from the C-18/milk matrix was first washed with hexane (8 mL), and then the benzimidazoles were eluted with methylene chloride-ethyl acetate (1 + 2, v/v; 8 mL). The eluate contained benzimidazole analytes which were free from interfering compounds as determined by UV detection (photodiode array, 290 nm). Correlation coefficients of standard curves for individual benzimidazoles isolated from spiked samples were linear (0.989 ± 0.003 to 0.998 ± 0.001) with recoveries ranging from 70 ± 9% to 107 ± 2% for the concentration range (62.5-2000 ng/mL) examined. The inter- assay variabilities ranged from 4 ± 1% to 9 ± 7% with intra-assay variabilities of 3-6%.

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