A specific method for the determination of polar allyl compounds

1962 ◽  
Vol 189 (4) ◽  
pp. 309-320 ◽  
Author(s):  
Koloman Bencze
Keyword(s):  
Specific Method ◽  
Allyl Compounds

Micro-Determination of p-Hydroxybenzoic Esters in Pharmaceuticals and Cosmetics

1977 ◽  
Vol 60 (1) ◽  
pp. 56-59 ◽  
Author(s):  
Emil Weisenberg ◽  
Baruch Gershon ◽  
Judith Schoenberg
Keyword(s):  
Liquid Chromatography ◽  
Phosphate Ester ◽  
Specific Method ◽  
Gas Liquid Chromatography ◽  
Direct Extraction ◽  
Flame Photometric Detector ◽  
Phenol Derivatives ◽  
Margin Of Error ◽  
Diethyl Phosphate

Abstract A rapid and specific method is described for the determination of microamounts of methyl, propyl, and butyl p-hydroxybenzoic esters (parabens) in pharmaceuticals and cosmetics. The method involves the direct extraction of parabens into benzene or chloroform followed by derivatization with phosphorochloridate. The diethyl phosphate ester derivatives are cleaned up on a Florisil minicolumn and finally measured by gas-liquid chromatography on 5% OV-210 on Gas-Chrom Q. A flame photometric detector or a KCl thermionic detector may be used. The concentration response was linear up to 40 ng parabens. The reproducibility and margin of error were tested with fortified samples. This method may be applied to the estimation of other phenol derivatives.

Hapticity of asymmetric rhodium-allyl compounds in the light of real-space bonding indicators

2018 ◽  
Vol 233 (9-10) ◽  
pp. 615-626
Author(s):  
Stefan Mebs ◽  
Sabrina Imke Kalläne ◽  
Thomas Braun
Keyword(s):  
Real Space ◽  
Molecular Structures ◽  
Dft Study ◽  
Interaction Patterns ◽  
Ligand Interaction ◽  
Complex Metal ◽  
Allyl Compounds ◽  
Back Donation ◽  
Metal Ligand

Abstract Rhodium boryl complexes are valuable catalysts for hydro- or diboration reactions of alkenes, but can also react with ketones (R2C=O) and imines (R2C=NR′) giving rise to insertion products having formally Rh–R2C–O/NR′–B linkages. The resulting molecular structures, however, may show complex metal–ligand and ligand–ligand interaction patterns with often unclear metal–ligand connectivities (hapticities, ηn). In order to assign the correct hapticity in a set of asymmetric rhodium-allyl compounds with molecular structures indicating η1−5 bonding, a comprehensive DFT study was conducted. The study comprises determination of a variety of real-space bonding indicators derived from computed electron and pair densities according to the AIM, ELI-D, NCI, and DORI topological and surface approaches, which uncover the metal–ligand connectivties and suggest an asymmetric ligand–metal donation/metal–ligand back-donation framework according to the Dewar–Chatt–Duncanson model.

scholarly journals Isocratic High-Performance Liquid Chromatographic Method with Ultraviolet Detection for Simultaneous Determination of Levels of Voriconazole and Itraconazole and Its Hydroxy Metabolite in Human Serum

2005 ◽  
Vol 49 (8) ◽  
pp. 3569-3571 ◽  
Author(s):  
GholamAli Khoschsorur ◽  
Franz Fruehwirth ◽  
Sieglinde Zelzer
Keyword(s):  
Human Serum ◽  
Simultaneous Determination ◽  
High Performance ◽  
High Performance Liquid Chromatographic ◽  
Specific Method ◽  
Minimum Detectable Concentration ◽  
Detectable Concentration ◽  
One Step ◽  
Liquid Chromatographic

ABSTRACT A simple, specific method is presented for simultaneous determination of voriconazole and itraconazole and its metabolite, hydroxyitraconazole, in human serum using one-step liquid-liquid extraction and high-performance liquid chromatography. Linearity tests ranged from 0.1 to 8.0 μg/ml; the minimum detectable concentration was 0.03 μg/ml.

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 Spectrofluorimetric Determination of Vigabatrin and Gabapentin in Dosage Forms and Spiked Plasma Samples Through Derivatization with 4-Chloro-7-Nitrobenzo-2-Oxa-1,3-Diazole

2001 ◽  
Vol 84 (4) ◽  
pp. 1017-1024 ◽  
Author(s):  
Ekram M Hassan ◽  
Fathalla Belal ◽  
Omar A Al-Deeb ◽  
Nasr Y Khalil
Keyword(s):  
Reaction Pathway ◽  
Dosage Forms ◽  
Specific Method ◽  
Plasma Samples ◽  
Spiked Plasma ◽  
Highly Sensitive ◽  
Percent Recovery ◽  
Spectrofluorimetric Determination ◽  
Label Claim

Abstract A highly sensitive and specific method is proposed for the determination of vigabatrin (I) and gabapentin (II) in their dosage forms and spiked human plasma. The method is based on coupling the drugs with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in borate buffer at pH 7.1 and measuring the resulting fluorescence at 532 nm after excitation at 465 nm. The fluorescence intensity was a linear function of the concentration of the drugs over the ranges of 1.3–6.5 and 1.7–8.5 μg/mL for I and II, respectively. Minimum detectability values were 0.54 μg/mL (4.2 × 10−6M) and 0.97 μg/mL (5.7 × 10−6M) for I and II, respectively, under the described conditions. The proposed method was successfully applied to the determination of the 2 drugs in their dosage forms, and the percent recoveries ± standard deviation (SD) were 104.53 ± 1.2 and 100.00 ± 1.32 of the label claim for I and II, respectively. The method was further applied to the determination of vigabatrin in spiked plasma samples. The percent recovery ± SD was 101.58 ± 2.68. Interference from endogenous α-amino acids was overcome through selective complexation with freshly prepared Cu(OH)2. The interference likely to be encountered from co-administered drugs, such as carbamazepine, cimetidine, clonazepam, clopazam, phenobarbital, valproic acid, and lamotrigine, was also studied. A reaction pathway is suggested.

Collaborative Study of the Microanalytical Determination of Iodine by Oxygen Flask Combustion

1973 ◽  
Vol 56 (4) ◽  
pp. 888-891
Author(s):  
Roger A Lalancette ◽  
Al Steyermark ◽  
Donna M Lukaszewski ◽  
Patti L Kostrzewski
Keyword(s):  
Organic Compounds ◽  
Statistical Evaluation ◽  
Collaborative Study ◽  
Specific Method ◽  
Iodobenzoic Acid

Abstract Twenty-two collaborators participated in the study of a specific method using oxygen flask combustion followed by mercurimetric titration of the resulting iodide. With the exception of 2 collaborators, all obtained acceptable results on m-iodobenzoic acid. Statistical evaluation of the data from all collaborators gave: x̿ = 51.07%, x̿ – theory = –0.10%, s̄ = 0.28, and sm = 0.94. When the results of 2 collaborators are omitted, the corresponding values are: 51.07%, –0.10%, 0.15, and 0.19, respectively. Similar results were obtained on p-nitroiodobenzene. The results from all collaborators gave: x̿ = 50.82%, x̿ – theory = – 0.14%, s̄ = 0.19, and sm = 0.43. When the results of 3 collaborators are omitted, the values are: 50.87%, –0.09%, 0.14, and 0.23, respectively. The method has been adopted as official first action, as an alternative to the Carius method, for the determination of iodine in organic compounds.

scholarly journals Development of a Sensitive and Reliable UHPLC-MS/MS Method for the Determination of Multiple Urinary Biomarkers of Mycotoxin Exposure

Toxins ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 193 ◽  
Author(s):  
Zhezhe Liu ◽  
Xiaoxue Zhao ◽  
Libiao Wu ◽  
Shuang Zhou ◽  
Zhiyong Gong ◽  
...  
Keyword(s):  
Human Urine ◽  
Solid Phase ◽  
Accurate Determination ◽  
Fumonisin B1 ◽  
High Sensitivity ◽  
Human Biomonitoring ◽  
Urine Samples ◽  
Specific Method ◽  
Alternariol Monomethyl Ether

A variety of mycotoxins from different sources frequently contaminate farm products, presenting a potential toxicological concern for animals and human. Mycotoxin exposure has been the focus of attention for governments around the world. To date, biomarkers are used to monitor mycotoxin exposure and promote new understanding of their role in chronic diseases. The goal of this research was to develop and validate a sensitive UHPLC-MS/MS method using isotopically-labeled internal standards suitable for accurate determination of 18 mycotoxin biomarkers, including fumonisins, ochratoxins, Alternaria and emerging Fusarium mycotoxins (fumonisin B1, B2, and B3, hydrolyzed fumonisin B1 and B2, ochratoxin A, B, and alpha, alternariol, alternariol monomethyl ether, altenuene, tentoxin, tenuazonic acid, beauvericin, enniatin A, A1, B, and B1) in human urine. After enzymatic digestion with β-glucuronidase, human urine samples were cleaned up using HLB solid phase extraction cartridges prior to instrument analysis. The multi-mycotoxin and analyte-specific method was validated in-house, providing satisfactory results. The method provided good linearity in the tested concentration range (from LOQ up to 25–500 ng/mL for different analytes), with R2 from 0.997 to 0.999. The limits of quantitation varied from 0.0002 to 0.5 ng/mL for all analytes in urine. The recoveries for spiked samples were between 74.0% and 133%, with intra-day precision of 0.5%–8.7% and inter-day precision of 2.4%–13.4%. This method was applied to 60 urine samples collected from healthy volunteers in Beijing, and 10 biomarkers were found. At least one biomarker was found in all but one of the samples. The high sensitivity and accuracy of this method make it practical for human biomonitoring and mycotoxin exposure assessment.

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