scholarly journals Boosting basic-peptide separation through dynamic electrostatic-repulsion reversed-phase (d-ERRP) liquid chromatography

RSC Advances ◽  
2020 ◽  
Vol 10 (21) ◽  
pp. 12604-12610
Author(s):  
Giulia Mazzoccanti ◽  
Simone Manetto ◽  
Michele Bassan ◽  
Alberto Foschini ◽  
Andrea Orlandin ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Method ◽  
Reversed Phase ◽  
Electrostatic Repulsion ◽  
Peptide Separation ◽  
Basic Peptide ◽  
Related Impurities

A simple and effective chromatographic method has allowed unprecedented resolution of basic peptide and their related impurities, including the very challenging epimeric isobaric ones.

Determination of Cymiazole Residues in Honey by Liquid Chromatography

1993 ◽  
Vol 76 (1) ◽  
pp. 92-94 ◽  
Author(s):  
Paolo Cabras ◽  
Marinella Melis ◽  
Lorenzo Spanedda
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Analysis ◽  
Mobile Phase ◽  
Chromatographic Method ◽  
Reversed Phase ◽  
Limit Of Determination ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic ◽  
Control Samples

Abstract A liquid chromatographic method is described for the determination of cymiazole residues in honey. This acaricide is determined on a reversed-phase (C18) column, with a CH3CN-O.OOIN HCI-NaCI mixture (950 mL + 50 mL + 0.3 g/L) as the mobile phase, and UV detection at 265 nm. Cymiazole is extracted with n-hexane from aqueous alkalinized (pH 9) honey solutions. No further cleanup of the honey extract was required before chromatographic analysis. Recoveries on control samples fortified with 0.01,0.10, and 1.00 ppm cymiazole ranged from 92 to 102%. The limit of determination was 0.01 ppm.

scholarly journals  Simple, selective, and sensitive measurement of urea in body fluids of mammals by reversed-phase ultra-fast liquid chromatography

2012 ◽  
Vol 57 (No. 1) ◽  
pp. 19-27 ◽  
Author(s):  
M. Czauderna ◽  
J. Kowalczyk
Keyword(s):  
Liquid Chromatography ◽  
Biological Samples ◽  
Chromatographic Method ◽  
Rapid Determination ◽  
Reference Sample ◽  
Reversed Phase ◽  
Body Fluids ◽  
Farm Animals ◽  
Array Detector ◽  
Fast Liquid Chromatography

Ultra-fast liquid chromatography with a photodiode array detector for simple and rapid determination of urea in body fluids of farm animals is described. Blood plasma, milk, and urine samples are treated with trichloroacetic acid and then centrifuged. Supernatants are derivatized at room temperature using p-dimethylaminobenzaldehyde. Samples are separated using a ternary gradient of methanol in buffer and water. Derivatized urea in standards and biological samples is analyzed using a Phenomenex C<sub>18</sub>-column (Synergi 2.5 &micro;m, Hydro-RP, 100&Aring;, 100 &times; 2 mm). The photodiode detector is set to 370 and/or 254 nm for detection. Temperature is maintained at 27&deg;C by a column heater. Clear separation of derivatized urea from the endogenous species present in assayed biological samples was achieved in less than 6 min. The urea adduct peak eluted at 4.36 &plusmn; 0.05 min. Average recoveries of the urea standards added to assayed biological materials were satisfactory (i.e. 100.2 &plusmn; 4.1%). Our chromatographic method with photodiode detection at 370 nm and at 254 nm, in particular, offers low detection (L<sub>D</sub>) and quantification limits (L<sub>Q</sub>) (<sup>370nm</sup>L<sub>D</sub> = 0.47&nbsp;ng, <sup>254nm</sup>L<sub>D</sub> = 0.027 ng and <sup>370nm</sup>L<sub>Q</sub> = 1.41 ng, <sup>254nm</sup>L<sub>Q</sub> = 0.080 ng, respectively). Our liquid chromato-graphy based on detection at 370 nm is the most versatile analytical tool that assures sensitive, accurate, and precise analysis of urea in urine, milk, and plasma samples, and selected diets for mammals. The presented chromatographic procedure is especially suitable for preparation of reference sample sets, very accurate and precise research purposes or rapid clinical diagnostic with smaller sample sets. Urea in urine can be also determined using our liquid chromatography with detection at 254 nm. Detection of urine urea at 254 nm is more sensitive and precise compared with monitoring at 370 nm. Our chromatographic method based on photodiode detection at 370 nm and especially at 254 nm is suitable for the non-invasive analysis of urea in only urine of humans and animals. &nbsp; &nbsp;

Development and Validation of a Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) Method for Identification, Assay and Estimation of Related Substances of Ivermectin in Bulk Drug Batches of Ivermectin Drug Substance

2021 ◽  
Author(s):  
Daoli Zhao ◽  
Rasangi M Wimalasinghe ◽  
Lin Wang ◽  
Abu M Rustum
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Degradation Products ◽  
Reversed Phase ◽  
Hplc Method ◽  
Drug Substance ◽  
Related Impurities ◽  
Rp Hplc ◽  
Bulk Drug

Abstract A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for the identification and assay of Ivermectin, including the identification and estimation of its process-related impurities and degradation products in bulk drug substance of Ivermectin. Analytes were separated on a HALO C18 column (100 mm × 4.6 mm I.D., 2.7 μm particle size) maintained at 40 °C (column temperature) with gradient elution. All analytes of interests were adequately separated within 25 min. All degradation products, process-related impurities and assay were monitored by ultraviolet detection at 254 nm. The new HPLC method described here successfully separated an isomer peak of the active pharmaceutical ingredient (API) from the major API peak. This newly separated isomer peak is around 1.2 to 1.5% (peak area) in typical API samples, and coelutes with the major API peak by all current HPLC methods. Quantitation limit of the HPLC method is 0.1% of target analytical concentration (~1.0 μg/mL). This method has been demonstrated to be accurate, robust, significantly higher degree of selectivity compared to the HPLC methods of Ivermectin drug substance reported in the literature and in the compendial HPLC methods prescribed in the current USA and European Pharmacopeia.

scholarly journals Quantification of residual AEBSF-related impurities by reversed-phase liquid chromatography

2019 ◽  
Vol 1116 ◽  
pp. 19-23 ◽  
Author(s):  
Cindy X. Cai ◽  
Nicole A. Schneck ◽  
Doug Harris ◽  
Daniel Blackstock ◽  
Vera B. Ivleva ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Related Impurities ◽  
Phase Liquid

Simultaneous determination of catecholamines and serotonin by liquid chromatography, after treatment with boric acid gel.

1988 ◽  
Vol 34 (3) ◽  
pp. 528-530 ◽  
Author(s):  
Y Imai ◽  
S Ito ◽  
K Maruta ◽  
K Fujita
Keyword(s):  
Liquid Chromatography ◽  
Boric Acid ◽  
Chromatographic Method ◽  
Reversed Phase ◽  
Internal Standards ◽  
Column Temperature ◽  
Liquid Chromatographic Method ◽  
Acid Gel ◽  
Liquid Chromatographic

Abstract We describe a liquid-chromatographic method for simultaneously determining norepinephrine, epinephrine, dopamine, and serotonin in 0.5 mL of human plasma. These analytes are purified on boric acid gel from Aldrich, separated on a reversed-phase C18 column, and detected electrochemically at +600 mV. Absolute recoveries of internal standards were 84% for 3,4-dihydroxybenzylamine and 57% for N-methylserotonin. Reproducibility was good to excellent, depending on the concentration of the analytes. A chromatographic run is complete in 40 min, but this can be shortened by about half when the determination of only serotonin is required, by increasing the column temperature from 40 degrees C to 60 degrees C.

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