Anja Tumpa

Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities

This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm.

Quality by Design in the development of hydrophilic interaction liquid chromatography method with gradient elution for the analysis of olanzapine

HIGHLIGHTSThe first gradient HILIC method developed in accordance with AQbD.For complex HILIC method well defined design space was created.Olanzapine and its seven impurities investigated in HILIC for the first time.Method was fully validated and applied for real sample analysis. ABSTRACT This paper deals with the development of hydrophilic interaction liquid chromatography (HILIC) method with gradient elution, in accordance with Analytical Quality by Design (AQbD) methodology, for the first time. The method is developed for olanzapine and its seven related substances. Following step by step AQbD methodology, firstly as critical process parameters (CPPs) temperature, starting content of aqueous phase and duration of linear gradient are recognized, and as critical quality attributes (CQAs) separation criterion S of critical pairs of substances are investigated. Rechtschaffen design is used for the creation of models that describe the dependence between CPPs and CQAs. The design space that is obtained at the end is used for choosing the optimal conditions (set point). The method is fully validated at the end to verify the adequacy of the chosen optimal conditions and applied to real samples.

Application of Analytical Quality by Design concept for bilastine and its degradation impurities determination by hydrophilic interaction liquid chromatographic method

This paper deals with the development of hydrophilic interaction liquid chromatographic (HILIC) method for the analysis of bilastine and its degradation impurities following Analytical Quality by Design approach. It is the first time that the method for bilastine and its impurities is proposed. The main objective was to identify the conditions where an adequate separation in minimal analysis duration could be achieved within a robust region. Critical process parameters which have the most influence on method performance were defined as acetonitrile content in the mobile phase, pH of the aqueous phase and ammonium acetate concentration in the aqueous phase. Box-Behnken design was applied for establishing a relationship between critical process parameters and critical quality attributes. The defined mathematical models and Monte Carlo simulations were used to identify the design space. Fractional factorial design was applied for experimental robustness testing and the method is validated to verify the adequacy of selected optimal conditions: the analytical column Luna(®) HILIC (100mm×4.6mm, 5μm particle size); mobile phase consisted of acetonitrile-aqueous phase (50mM ammonium acetate, pH adjusted to 5.3 with glacial acetic acid) (90.5:9.5, v/v); column temperature 30°C, mobile phase flow rate 1mLmin(-1), wavelength of detection 275nm.

Hydrophilic interaction liquid chromatography in analysis of granisetron HCl and its related substances. Retention mechanisms and method development

In this paper separation of granisetron and its two related substances in HILIC mode is presented. Separation was done on silica column derivatized with sulfoalkylbetaine groups (ZIC-HILIC). Firstly, retention mechanisms were assessed whereby retention factors of substances were followed in wide range of acetonitrile content (80-97%), at constant concentration of aqueous buffer (10mM) as well as at constant pH value of 3.0. Further, in order to developed optimal HILIC method, Design of Experiments (DoE) methodology was applied. For optimization full factorial design 3(2) was employed. Influence of acetonitrile content and ammonium acetate concentration were investigated while pH of the water phase was kept at 3.3. Adequacy of obtained mathematical models was confirmed by ANOVA. Optimization goals (α>1.15 and minimal run time) were accomplished with 94.7% of acetonitrile in mobile phase and 70 mM of ammonium acetate in water phase. Optimal point was in the middle of defined Design Space. In the next phase, robustness was experimetally tested by Rechtschaffen design. The investigated factors and their levels were: acetonitrile content (±1%), ammonium acetate molarity in water phase (±2 mM), pH value of water phase (±0.2) and column temperature (±4 °C). The validation scope included selectivity, linearity, accuracy and precision as well as determination of limit of detection (LOD) and limit of quantification (LOQ) for the related substances. Additionally, the validation acceptance criteria were met in all cases. Finally, the proposed method could be successfully utilized for estimation of granisetron HCl and its related substances in tablets and parenteral dosage forms, as well as for monitoring degradation under various stress conditions.

Quality by Design Determination of Diclofenac Potassium and its Impurities by High-Performance Liquid Chromatography

ABSTRACT A liquid chromatography method is reported for the determination of diclofenac potassium and its impurities using Quality by Design criteria. Central composite design was used for the investigation of the influence of critical parameters on performance that included the methanol concentration in the mobile phase, the pH of the aqueous phase, and the potassium dihydrogen phosphate concentration in the aqueous phase. Mathematical models enabled theoretical examination of experimental space to achieve maximal separation in minimal analysis time. A Monte Carlo simulation was used to evaluate the risk of uncertainty in model predictions, to adjusting process parameters, and to identify design space. Fractional factorial design was employed for robustness testing and method was fully validated. Optimal conditions were a C18 150 mm × 4.6 mm, 5 µm particle size column; a methanol −68.3 m mol L−1 potassium dihydrogenphosphate (68.7:31.3, v/v) mobile phase at pH 3.0, a flow rate of 1 mL min−1, a column temperature of 25°C, and ultraviolet detection at 254 nm.

Optimization of Chromatographic Separation of Acetylsalicylic Acid, Amlodipine, Impurity A of Amlodipine, and Atenolol in Hydrophilic Interaction Liquid Chromatography Employing DoE Methodology

The retention behavior of substances in hydrophilic interaction liquid chromatography (HILIC) is difficult to predict. Mixture investigated in this paper consists of acetylsalicylic acid, amlodipine, impurity A of amlodipine, and atenolol, a very often used combination in treatment of some cardiovascular diseases. Retention behavior dependence on the most influential chromatographic factors is described by mathematical models, with the special emphasis on pH of the mobile phase. D-optimal design is applied to generate more complex models and to obtain more accurate results. Comparison of Predicted R2 values of quadratic and cubic model for pH dependence (0.847 and 0.934, respectively) shows that the cubic model has significantly better prediction ability than quadratic in the investigated system. After describing retention behavior, chemometrical tools (indirect modeling of complex chromatographic responses and grid point search optimization) are used to locate the optimal conditions for analyzed mixture in terms of satisfactory separation and minimal analysis duration. The optimal conditions are Column: Kinetex HILIC 100 A (100 mm × 4.5 mm, 2.6 µm particle size); injection volume: 5 μL; flow rate: 1 mL min−1; column temperature: 30°C; detection wavelength: 254 nm; mobile phase: acetonitrile–water phase (75 mM ammonium acetate, pH 5.3) (91:9 V/V).

Theoretical Models and QSRR in Retention Modeling of Eight Aminopyridines.

In this article, retention modeling of eight aminopyridines (synthesized and characterized at the Faculty of Pharmacy) in reversed-phase high performance liquid chromatography (RP-HPLC) was performed. No data related to their retention in the RP-HPLC system were found. Knowing that, it was recognized as very important to describe their retention behavior. The influences of pH of the mobile phase and the organic modifier content on the retention factors were investigated. Two theoretical models for the dependence of retention factor of organic modifier content were tested. Then, the most reliable and accurate prediction of log k was created, testing multiple linear regression model-quantitative structure-retention relationships (MLR-QSRR) and support vector regression machine-quantitative structure-retention relationships (SVM-QSRR). Initially, 400 descriptors were calculated, but four of them (POM, log D, M-SZX/RZX and m-RPCG) were included in the models. SVM-QSRR performed significantly better than the MLR model. Apart from aminopyridines, four structurally similar substances (indapamide, gliclazide, sulfamethoxazole and furosemide) were followed in the same chromatographic system. They were used as external validation set for the QSRR model (it performed well within its applicability domain, which was defined using a bounding box approach). After having described retention of eight aminopyridines with both theoretical and QSRR models, further investigations in this field can be conducted.

Modeling of HILIC retention behavior with theoretical models and new spline interpolation technique

When it is taken into account that hydrophilic interaction liquid chromatography (HILIC) as an analytical method is relatively young compared with the other techniques, retention modeling could still bring scientifically valuable data to the field. Therefore, in this paper, olanzapine and its 8 impurities were selected as a test mixture, considering that they have never been analyzed in HILIC before. Their investigation on 4 different HILIC columns (bare silica, cyanopropyl, diol and zwitterionic) has been performed. The mixture of 9 structurally similar substances allows the examination of complex HILIC retention behavior depending on the chemical properties of the analytes, as well as of the stationary phase. To describe the nature of the relationship between the retention and the stronger eluent content in the mobile phase, we fitted experimentally obtained data to several theoretical (localized adsorption, nonlocalized partition, quadratic, and mixed) models. Results show that the best fit is the quadratic model with the highest R2 and cross‐validated coefficient of determination (Q2) values, but its usage has some drawbacks. With the aim to improve the possibility to predict retention behavior in HILIC, a new empirical model was proposed. For that purpose, a spline interpolation technique was performed, by dividing the experimental range into several subdivisions. This type of interpolation was performed for the first time in the chromatographic field. The estimation of the polynomial equations was performed using Q2 values. Obtained Q2 values pointed out the goodness of fit of the model, as well as its good predictive capabilities. In the end, the prediction capabilities were experimentally verified, under randomly chosen conditions from the experimental range. The errors in prediction were all under 10%, which is satisfying for HILIC.