Validated Capillary Zone Electrophoresis Method for Impurity Profiling and Determination of NiII(3-OMe-Salophene)

Sami El Deeb,Adel Ehab Ibrahim,Ahmed Al-Harrasi,Ronald Gust,Gerhard Wolber

doi:10.3390/separations9020025

Abstract

A capillary zone electrophoresis method was developed for the determination of NiII(3-OMe-salophene), a substance with anticancer activity in vitro. A fused silica capillary (56 cm × 100 µm) was used for this purpose. The method was optimized in terms of parameters affecting the electrophoretic conditions in order to optimize separation efficiency and total time of migration. The analysis was best performed using an operating buffer of 50 mM borate, adjusted to pH 9.3, mixed with acetonitrile (50%, v/v) as organic modifier. Injections were performed hydrodynamically by applying a pressure of 50 mbar for 8 s, and a 30 kV separation voltage was selected at 25 °C. Detection was carried out at 250 nm using diode array detector (DAD). The method allowed the separation of NiII(3-OMe-salophene) from four other structurally related impurities in a total migration time (tm) of 8 min. Peak identification was achieved using the standard reference of individual impurities. The purity of the migrated NiII(3-OMe-salophene) was confirmed by Ultra-violet (UV) scan overlay depending on DAD. The linear ranges for the determination of NiII(3-OMe-salophene) was 400–20,000 ng mL−1 with limit of detection (LOD) of 120 ng mL−1. Acceptable intra-day and inter-day precisions were achieved (%relative standard deviation (RSD) results were less than 0.76% and 0.30%, respectively). The proposed method was assessed for greenness and compared to reported methodologies to prove superiority.

Highlights

A capillary zone electrophoresis method was developed for the determination of NiII(3-OMe-salophene), a substance with anticancer activity in vitro
The linear ranges for the determination of NiII(3-OMe-salophene) was 400–20,000 ng mL−1 with limit of detection (LOD) of 120 ng mL−1
Three quality control (QC) standards were prepared at low (QCL), medium (QCM) and high (QCH) concentration levels within the linearity range at concentrations of 400, 2000, and 20,000 ng mL−1

Summary

Introduction

Cancer remains the most seriously undefeated illness of recent decades. Despite the eager efforts of clinical researchers to find new therapies, cancer morbidity and mortality rates remain worrying. In 2009, Hille et al developed a metal chelating ligand known as salophene (N,N -bis(salicylidene)-1,2-phenylenediamine), which can form metal complexes with transition metals such as (FeII&III, CoII, NiII, MnII&III, and CuII) [1]. Such complexes exhibited dose dependent anti-proliferative activity against breast cancer cell line MCF-7, where its cytotoxicity depended on the complexed metal [1]. EMealteecrtiraolsphoresis (CZE) method for the determination of the target antitumor drug, NiII(3-OMe-salophene), in the presence of the aforementioned structurally related PRIs. The lSitoedraituumre hreyvdireowxirdeeveaanleddbtohraitcoancliydowneerpeuabnliacalytitoicnalhagdrardeepsoratnedd ownetrheeodbettaeirnmedinafrtoiomn oSifgNmiIaI-(A3-lOdMriceh-s(aSlotepihnehneeim) u, sGinegrmataonmyi)c. All separations were carried out on a bare fused silica capillary (56 cm length × 100 μm internal diameter), which was purchased from Polymicro Technologies (Phoenix, AZ, USA). All acquired data were analyzed using Microsoft EXCEL® (Microsoft Corporation, Redmond, WA, USA, version 2010)

CZE Separation Conditions

Preparation of Standard and Stock

Method Development

Method Validation

Result

Evaluation of the Proposed Method