Separation Differences Among Phenyl Hydride, Udc Cholesterol, and Bidentate C8 Stationary Phases for Stability Indicating Methods of Tetracyclines

Abstract

Formulation extracts of tetracycline hydrochloride (HCl), minocycline hydrochloride (HCl), and doxycycline hyclate were degraded by strong acidic conditions and heating. Subsequently, components of the extracts were separated by Bidentate C8, Phenyl Hydride and Cholesterol (UDC) HPLC columns operating in the reverse phase mode. The Phenyl Hydride column was able to baseline separate minocycline from the observed degradant, while partial or total co-elution was observed with the other two columns using otherwise identical method conditions. For both the degraded tetracycline HCl and doxycycline hyclate extracts, the UDC column gave the best resolution for the critical pair. The findings suggest that the postulated secondary retention mechanisms of π–π interactions from the Phenyl Hydride and shape selectivity from the UDC can provide superior resolution for structurally similar analytes compared to hydrophobic interactions alone.

Transcriptomic Analysis of the Underground Renewal Buds during Dormancy Transition and Release in ‘Hangbaishao’ Peony (Paeonia lactiflora)

“…The steamed and dried root of ‘Hangbaishao’ and some other medicinal cultivars of P . lactiflora is white, so the root is often referred to as “Bai-shao”[ 34 ], “Radix Paeoniae Alba”[ 34 ] or “White peony root”[ 35 ] in some literatures, and has always been used as herbal supplement. Therefore, ‘Hangbaishao’ is an ideal and valuable material with strong local adaptability, relatively low chilling requirements and multiple uses to study the dormancy mechanism of herbaceous peonies in the winter in warm temperate or subtropical areas, such as Zhejiang Province.…”

Evaluation of stationary phases based on silica hydride for the analysis of drugs of abuse

“…Therefore, another stationary phase, a silica hydride based phenyl material, was selected for evaluation on the assumption that π–π interactions may provide the discrimination to resolve the two pairs of compounds having the same m / z . The hydride‐based phenyl phase has been shown to be an effective separation medium for tetracylines . These compounds all have aromatic rings so that the π–π mechanism could provide the additional type of interaction necessary to be able to separate each pair of compounds.…”

A Comparative Evaluation of Polystyrene Divinylbenzene Copolymer HPLC Columns on the Chromatographic Performance of the Compendial Method for Doxycycline Hyclate Capsules: Implications for Method Implementation of a Medical Countermeasure Medication

“…The mobile phase plays an important role in the chromatographic performance of the respective columns. As per our observations, using an alkali mobile phase has several disadvantages when applied to this compendial method: 1) alkali pH of the mobile phase could trigger the formation of isomeric analogues [25]; 2) chelating agents, such as EDTA, are needed in the mobile phase to increase column efficiency because support surface of tetracyclines is fully activated at alkali pH [21]; tetrabutylammonium hydrogen sulfate, an ion-pair agent, is used to reduce peak tailing due to ionized nature of the analytes at higher pH, which may cause a less robust method, longer equilibration and run times along with shorter column life [6] [19]. However, more acidic conditions could result in significantly increased retention times due to the possible hydrophobic interactions between the column and the analytes.…”

“…Ion-pair reagents are a standard approach for modifying the mobile phase, generally to reduce tailing and enhance resolution. It is thought that they are electrostatically adsorbed onto the surface of the column and the retention of the analytes is probably based on the interaction with the hydrophobic parts of the ion-pair agent [19] [20]. The method provides an accurate and reproducible determination of doxycycline hyclate and their impurities in pharmaceutical samples.…”