Determination of Dephosphate Bromofenofos in Milk by Liquid Chromatography with Electrochemical Detection

1994 ◽  
Vol 77 (4) ◽  
pp. 904-908 ◽  
Author(s):  
Kazue Takeba ◽  
Takeshi Itoh ◽  
Masao Matsumoto ◽  
Hiroyuki Nakazawa
Keyword(s):  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
Potassium Dihydrogen Phosphate ◽  
Reversed Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Dihydrogen Phosphate ◽  
Specific Method ◽  
Coefficients Of Variation ◽  
The Matrix

Abstract A sensitive, specific method for the determination of dephosphate bromofenofos (DBFF) in milk by liquid chromatography (LC) with electrochemical detection is described. DBFF, the only metabolite of bromofenofos (BFF, a fasciolicide), was extracted from milk by liquid–liquid partition with acetone, acetonitrile, and dichloromethane and purified by using a C18 cartridge. The compound was separated from the matrix peaks by reversed-phase LC and detected by dual-electrode coulometric detection on a Kaseisorb LC ODS-300-5 (250 × 4.6 mm id, 5 μm) column. The mobile phase was acetonitrile–0.05M potassium dihydrogen phosphate (55 + 45, v/v) at pH 3.0. The flow rate was 1 mL/min at 40°C. The applied potentials of detectors 1 and 2 were maintained at 0.30 and 0.45 V, respectively. Average recoveries (n = 5) of DBFF from milk spiked at 1 and 10 ng/mL were 73.1 and 82.7%, respectively; and coefficients of variation were 8.4 and 2.8%, respectively. The detection limit of DBFF in milk was 0.2 ng/mL. Fifty-nine raw and 181 commercial milks were analyzed. DBFF was detected in 4 raw milks (0.2–1.5 ng/mL; average, 0.6 ng/mL) and in 3 normal liquid commercial milks (0.3–0.7 ng/mL; average, 0.5 ng/mL). The identity of DBFF from milk was confirmed by gas chromatography/mass spectrometry.

scholarly journals Simultaneous Determination of Five Fasciolicides in Milk by Liquid Chromatography with Electrochemical Detection

1996 ◽  
Vol 79 (4) ◽  
pp. 848-852 ◽  
Author(s):  
Kazue Takeba ◽  
Takeshi Itoh ◽  
Masao Matsumoto ◽  
Hlroyuki Nakazawa ◽  
Shinzo Tanabe
Keyword(s):  
Liquid Chromatography ◽  
Potassium Dihydrogen Phosphate ◽  
Reversed Phase ◽  
Dihydrogen Phosphate ◽  
Specific Method ◽  
Hydrogen Carbonate ◽  
The Matrix ◽  
Phase Liquid ◽  
Liver Flukes

Abstract A sensitive and specific method is described for determination of 5 fasciolicides in milk. The drugs are used to control liver flukes in cattle. The milk sample was homogenized with acetone and acetonitrile, sonicated, and centrifuged. The supernatant was extracted with dichloromethane. The extract was evaporated to dryness, dissolved in 1 % sodium hydrogen carbonate, and purified on a C18 cartridge. The 5 drugs were separated from the matrix by reversed-phase liquid chromatography (LC) and determined by dual-electrode coulometric detection on a Kaseisorb LC ODS-300-5 column. The mobile phase was acetonitrile-0.05M potassium dihydrogen phosphate (55 + 45) at pH 3.0. The flow rate was 1 mL/min at 40°C. The applied potentials of detectors 1 and 2 were set at 0.20 and 0.55 V, respectively. The average recovery of the drugs added to milk at 0.01 and 0.1 µ g/mL was 89.6%, and the coefficient of variation was 4.7%. The detection limits of the drugs in milk were 4-20 ng/mL. The method is used to monitor commercial milk samples and to determine the residual levels of these drugs in milk from cows treated with a fasciolicide.

Separation and Determination of Tetrahydrofolylpolyglutamates and their 5-Methyl Derivatives by Reversed-phase High-performance Liquid Chromatography with Electrochemical Detection

Pteridines ◽  
1989 ◽  
Vol 1 (2) ◽  
pp. 99-102
Author(s):  
Masahiro Kohashi ◽  
Asako Takahashi ◽  
Kazuo Iwai
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Potassium Dihydrogen Phosphate ◽  
Reversed Phase ◽  
Dihydrogen Phosphate ◽  
Electrochemical Detector ◽  
Methyl Derivatives

SummaryA highly sensitive method for the separation and quantitation of tetrahydrofolylpolyglutamates (H4PteGlun ) and their 5-methyl derivatives (CH3H4PteGlun) of different chain lengths by a reversed phase high-performance liquid chromatography with electrochemical detection is described. These compounds have been separated using a cosmosil 5-Ph column eluted with 50 mM potassium dihydrogen phosphate, pH 2.2, containing 0.05 M disodium EDTA and 1 % methanol at a tlow-rate of 1.5 ml/min, and an electrochemical detector (at a potential of + 350 mV versus the Ag/AgCI electrode). Good separation has been obtained on both H4PteGlun and CH3H4PteGIun derivatives containing up to 6 glutamyl residues. The detection limits at a signal-to-noise ratio of 3 for H4PteGlun and CH3H4PteGIun series (n = 1 - 6) were 1 -10 and 10 -15 pmol, respectivel y.

scholarly journals Development and validation of a reversed-phase HPLC method for determination of assay content of Teriflunomide by the aid of BOMD simulations

2021 ◽  
pp. 281-294 ◽  
Author(s):  
Abolghasem Beheshti ◽  
Zahra Kamalzadeha ◽  
Monireh Haj-Maleka ◽  
Meghdad Payaba ◽  
Mohammad Amin Rezvanfar ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Potassium Dihydrogen Phosphate ◽  
Active Pharmaceutical Ingredient ◽  
Reversed Phase ◽  
Hplc Method ◽  
Dihydrogen Phosphate ◽  
Td Dft ◽  
High Level ◽  
Development And Validation

Due to the new hopes for treatment of multiple sclerosis (MS) diseases by Teriflunomide (TFN), in this project, a cheap, robust, and fully validated method has been developed both for determination of assay content in API (active pharmaceutical ingredient), and for related impurities analysis (RIA). To operate the method, a common C18, end-capped (250 × 4.6) mm, 5µm liquid chromatography column, was applied. The mobile phase A was prepared by dissolving 2.74 g (20mM) of PDP (potassium dihydrogen phosphate) and 3.72 g (50mM) of PC (potassium chloride) in water (1000 mL). Then, pH was adjusted to 3.0 by adding OPA (ortho-phosphoric acid) 85%; while, the mobile phase B was acetonitrile (ACN) (100%). In order to confirm the experimental data about the λmax of TFN, we have used the Born-Oppenheimer molecular dynamics (BOMD) simulations, quantum mechanics (QM), and TD-DFT calculations. According to the results, the method showed a high level of suitability, specificity, linearity, accuracy, precision, repeatability, robustness, and reliable detection limit.

Determination of urinary normetanephrine and metanephrine by radial-compression liquid chromatography and electrochemical detection.

1983 ◽  
Vol 29 (2) ◽  
pp. 305-309 ◽  
Author(s):  
P J Orsulak ◽  
P Kizuka ◽  
E Grab ◽  
J J Schildkraut
Keyword(s):  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
Depressive Disorders ◽  
Internal Standard ◽  
Normal Subjects ◽  
Reversed Phase ◽  
Radial Compression ◽  
Ion Pair Chromatography ◽  
Catecholamine Metabolites

Abstract A procedure has been developed for determining the O-methylated catecholamine metabolites, normetanephrine and metanephrine, in urine by use of radial-compression liquid chromatography followed by electrochemical detection. Normetanephrine and metanephrine are isolated from hydrolyzed urine by ion-exchange on small, commercially available, disposable columns and preconcentrated by solvent extraction. They are then separated by reversed-phase ion-pair chromatography, with use of a radial compression cartridge and radial compression module, and quantified with 3-methoxy-4-hydroxybenzylamine as internal standard. Normetanephrine, metanephrine, and the internal standard are separated from interfering peaks in about 15 min. The method is applicable to the relatively low amounts of normetanephrine (100-600 micrograms/24 h) and metanephrine (50-400 micrograms/24 h) found in normal subjects and patients with depressive disorders or hypertension. Within-day CVs ranged from 1.1 to 2.2% for normetanephrine and 1.2 to 6.9% for metanephrine; the corresponding between-day CVs were 4.9 and 5.7% over these ranges.

Determination of nifedipine in serum or plasma by reversed-phase liquid chromatography.

1983 ◽  
Vol 29 (7) ◽  
pp. 1344-1348 ◽  
Author(s):  
P R Bach
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Extraction Column ◽  
Phase Extraction ◽  
Reversed Phase Liquid Chromatography ◽  
Ultraviolet Absorbance ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Phase Liquid

Abstract Therapeutic concentrations of nifedipine in serum or plasma were measured by reversed-phase liquid chromatography, with detection by ultraviolet absorbance at 235 nm. In the procedure a disposable reversed-phase extraction column is used. A 1-mL sample is required. The method is sensitive to 3 micrograms of nifedipine per liter and the standard curve is linear to at least 400 micrograms/L. Coefficients of variation at 100 micrograms/L were 2.2% within-run, 2.8% between-run. The method has been used to determine nifedipine in patients involved in a test of its efficacy in treating muscular dystrophy.

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