QbD approach to HPLC method development and validation of ceftriaxone sodium

Development and Validation of a Robust RP-HPLC Method for the Simultaneous Analysis of Exemestane and Thymoquinone and Its Application to Lipid-Based Nanoformulations

The present study describes the development and validation of a simple and rapid HPLC method for the simultaneous quantification of exemestane and thymoquinone. The separation of both compounds was performed on a 5 μ C-18 column utilizing phase A as water/methanol (45:5 v/v) and phase B as acetonitrile (50 v/v) (total ratio of A/B = 40:60 v/v) in isocratic elution mode as the mobile phase at a flow rate of 0.8 mL/min. Further, the Box-Behnken design was used for optimizing the analytical method. The proposed method was validated for various parameters, and all parameters were found to be within an acceptable range. The simultaneous detection of both drugs was monitored at 243 nm with a retention time of 5.73 and 6.93 min, respectively. Moreover, the forced degradation studies were conducted under various stress conditions, and the relevance of the validated RP-HPLC method was further explored for the estimation of drugs from lipid-based nanoformulation. Taken together, the study construed the development of an efficient and robust method that could be used for the quantification of these agents in various in vitro as well as in vivo models.

A Robust HPLC Approach for Quantitation of Camptothecin in Mesoporous Silica Nanoparticles Matrix and in the Presence of Its Degradation Products

BACKGROUND

Camptothecin is a potent anticancer drug used for the treatment of various cancers.

OBJECTIVE

The goal of this research investigation was to develop and validate a new stability-indicating HPLC technique for the quantitative assessment of camptothecin in in-house developed mesoporous silica nanoparticles, a novel nanoformulation matrix for the treatment of cancer.

METHOD

The Waters Inertsil® HPLC column (C18) was used for the chromatographic separation, with a flow rate of 1 mL/min, a column oven temperature of 40°C, an injection volume of 10 µL, a detection wavelength of 216 nm, and a 10 min runtime overall. An isocratic blend of phosphate buffer (10 mM, pH7.0) and acetonitrile (60:40, v/v) served as the mobile phase. Various stress conditions including acid, alkali, oxidative, photolytic, thermal, and humidity environments were tested for the quantitative estimation of the camptothecin through the proposed method.

RESULTS

The results demonstrated that the proposed method is specific (peak purity ≥0.999), accurate (99.69-100.64% w/w), precise (RSD, % <2.0), and sensitive (LOD-0.17 µg and LOQ-0.56 µg) in accordance with ICH guideline Q2 (R1). Any unidentified degradation products did not interfere with the drug's estimation. Furthermore, the current method of analysis has eliminated any excipient interference from the matrix effect caused by the numerous excipients of the formulation matrix.

CONCLUSIONS

To quantify camptothecin for routine assay purposes, this research work offers a novel and straightforward HPLC methodology with optimized chromatographic parameters, contributing to the research and development community while ensuring an appropriate and efficient use of the drug through a variety of nanoformulation for cancer treatment.

HIGHLIGHTS

The stability-indicating HPLC method was found to be specific and suitable for routine analysis of camptothecin. The absence of any interference from excipients was confirmed by forced degradation studies.

A brief review on application of design of experiment for the analysis of pharmaceuticals using HPLC

The quality pioneer Dr. Joseph M. Juran first proposed the idea of quality by design. According to him, pharmaceutical quality by design is an organised approach to product development that starts with predetermined goals and places an emphasis on product, process understanding, control based on reliable science and quality risk management. The quality of a product or process can typically be affected by a number of input elements. Design of experiments has been employed widely recently to understand the impacts of multidimensional and interactions of input parameters on the output responses of analytical procedures and pharmaceutical goods. Depending on the design of experiments objectives, screening, characterization, or optimization of the process and formulation, a variety of designs, such as factorial or mixture, can be used. The most popular designs used in the stage of screening or factor selection are the 2-Level Factorial and Plackett-Burman designs, both of which have two levels for each factor (k), both economical and effective, and in optimization widely used designs in this step are full factorial at three levels, central composite, Box-Behnken design. The analysis of variance, regression significance, and lack of fit of the regression model were some of the key topics covered in the discussion of the main components of multiple regression model adjustment. Design of experiments is thus the primary element of the formulation and analytical quality by design. The details about design of experiments used for the analysis of pharmaceutical formulation using HPLC.

Development of the RP-HPLC Method for Simultaneous Determination and Quantification of Artemether and Lumefantrine in Fixed-Dose Combination Pharmaceutical Dosage Forms

Developing countries face enormous challenges with substandard and falsified antimalarial drugs. One specific issue is the lack of a simple, cost-effective, and robust HPLC method to simultaneously determine and quantify the active pharmaceutical ingredients (APIs) in fixed-dose artemether-lumefantrine pharmaceutical dosage forms. The current study developed a novel, simple, sensitive, precise, accurate, and cost-effective RP-HPLC method for the simultaneous determination and quantification of artemether and lumefantrine in pharmaceutical dosage forms. The HPLC analysis was carried out on an Agilent 1260 Infinity Series HPLC system equipped with an ODS Intersil-C8 (150 × 4.6 mm) 5.0 µm column, by isocratic elution. The mobile phase composition consisted of acetonitrile and 0.05% orthophosphoric acid buffer of pH 3.5 in the ratio of 70 : 30 v/v. The analysis was performed at a 1 mL/min flow rate and a column temperature of 25°C. The total run time was 6 minutes. The detection was done with a variable wavelength detector (VWD) at an isosbestic point wavelength (λ) of 210 nm. The developed method was validated according to the ICH guidelines concerning system suitability, specificity, linearity, accuracy, precision, and robustness. The system suitability of the developed method revealed satisfactory theoretical plates and symmetry factors. The method proved to be specific, with no interference of mobile phase or excipients. The calibration plot exhibited linearity over the concentration range of 275-1925 μg/mL with R2 = 0.9992 for artemether and a range of 150-1050 μg/mL with R2 = 0.9985 for lumefantrine. The accuracy of the method, determined by the recovery study, was 99.79-100.16% for artemether and 99.04-99.50% for lumefantrine. The % RSD values for intraday precision were 0.175 and 0.203, while interday precision values were 0.340 and 0.554 for artemether and lumefantrine, respectively. The method demonstrated robustness when subjected to slight modifications in the flow rate, column temperature, and mobile phase composition. The developed analytical method proved satisfactory as per ICH guidelines and hence can be used for the determination and quantification of artemether and lumefantrine in bulk drug and pharmaceutical dosage forms.

HSPiP, Computational Modeling, and QbD-Assisted Optimized Method Validation of 5-Fluorouracil for Transdermal Products

This study addressed the simplest and most efficient HPLC (high-performance liquid chromatography) method for the estimation of 5-fluorouracil (5-FU) from rat blood plasma by implementing the Hansen solubility parameters (HSP), computation prediction program, and QbD (quality by design) tool. The mobile phase selection was based on the HSP predictions and experimental data. The Taguchi model identified seven variables (preoptimization) to screen two factors (mobile phase ratio as A and column temperature as B) at three levels as input parameters in "CCD (central composite design)" optimization (retention time as Y1 and peak area as Y2). The stability study (freeze-thaw cycle and short- and long-term stability) was conducted in the rat plasma. Results showed that HSPiP-based HSP values and computational model-based predictions were well simulated with the experimental solubility data. Acetonitrile (ACN) was relatively suitable over methanol as evidenced by the experimental solubility value, HSP predicted parameters (δh of 5-FU - δh of ACN = 8.3-8.3 = 0 as high interactive solvent whereas δh of 5-FU - δh of methanol = 8.3-21.7 = -13.4), and instrumental conditions. CCD-based dependent variables (Y1 and Y2) exhibited the best fit of the model as evidenced by a high value of combined desirability (0.978). The most robust method was adopted at A = 96:4 and B = 40 °C to get earlier Y1 and high Y2 as evidenced by high desirability (D) = 0.978 (quadratic model with p < 0.0023). The estimated values of LLOD and LLOQ were found to be 0.11 and 0.36 μg/mL, respectively with an accuracy range of 94.4-98.7%. Thus, the adopted method was the most robust, reliable, and reproducible methodology for pharmacokinetic parameters after the transdermal application of formulations in the rat.

High sensitivity, low-cost, and disposability: A novel screen-printed electrode developed for direct electrochemical detection of the antibiotic ceftriaxone

This study describes the development of a novel disposable and low-cost electrochemical platform for detecting the antibiotic ceftriaxone. The screen-printed electrode has been modified with a novel hybrid nanostructure containing silicon oxide (SiO2), zirconium oxide (ZrO2), and nitrogen-doped carbon quantum dots (Cdot-N). Different techniques like Fourier-transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy characterized the hybrid nanostructure used in the sensor surface modifier material. The hybrid nanostructure showed an excellent synergistic effect that contributed to the oxidation reaction of ceftriaxone. The screen-printed electrode modified with SiO2/ZrO2/Cdot-N nanostructure presented high sensitivity with a detection limit of 0.2 nmol L-1 in the linear range of 0.0078-40.02 μmol L-1. The measurements have been performed by square wave voltammetry technique. Studies on real samples of synthetic urine, urine, and tap water showed 95%-105% recovery without applying any sample pretreatment. The sensor demonstrated excellent selectivity in the antibiotic ceftriaxone determination in the presence of possible interferences cationic, Na+, K+, Ca2+, Mg2+, Cu2+, Pb2+, Mn2+, Zn2+, Co2+, and biological, glucose, caffeine, uric acid, and ascorbic acid. The developed sensor becomes a selective, sensitive, and applicable tool in determining the antibiotic ceftriaxone.

Discriminative Dissolution Method Development Through an aQbD Approach

Using a one-factor-at-a-time approach for dissolution method and discrimination analysis can be time-consuming and may not yield the optimal and discriminative method. To address this, we have developed a two-stage workflow for the dissolution method development followed by demonstration of discrimination power through an analytical Quality by Design (aQbD) approach. In the first stage, an optimal dissolution method was achieved by determining the method operable design region (MODR) through a design of experiment study of the high-risk method-related parameters. In the second stage, we established a Formulation-Discrimination Correlation Diagram strategy to examine the method discrimination capability, through which one can determine the method discriminative design region (MDDR) and visualize the impact of each formulation parameter and their interactions on dissolution. The application of aQbD principles into a workflow provides a scientific-driven guidance for robust method development and demonstrating discrimination power for dissolution methods.

HSPiP and QbD Program-Based Analytical Method Development and Validation to Quantify Ketoconazole in Dermatokinetic Study

Ketoconazole (KTZ) is the most potential azole anti-mycotic drug. The quantification of KTZ from various layers of the skin after topical application of lipidic nanocarriers is critical. We addressed a sensitive, specific, simple, rapid, reproducible, and economic analytical method to quantify KTZ from the treated skin homogenate using the Hansen solubility parameter (HSP, HSPiP software)-based modeling and experimental design. The software provided various HSP values for KTZ and solvents to compose the mobile phase. The Taguchi model identified the significant sets of factors to develop a robust bioanalytical method with reduced variability. In the optimization, acetonitrile (ACN) concentration (X1 as A) and the pH of mobile phase (X2 as B) were two factors against two responses (Y1: peak area and Y2: retention time). The HPLC (high-performance liquid chromatography) method validation was carried out based on US-FDA guidelines for the developed KTZ formulations (suspension, solid nanoparticles, and commercial product) extracted from the treated rat skin. The experimental solubility of KTZ was found to be maximum in the two solvents (ACN and ethyl acetate), based on HSP values. Surface response methodology (SRM) identified remarkable impact of ACN concentration and the mobile phase pH on the peak area and retention time. Analytical limits (0.17 and 0.50 µg/mL) were established for KTZ-SLNs (extracted from the skin). The method was implemented with high reproducibility, accuracy, and selectivity to quantify KTZ from the treated rat skin.

Validation of an Innovative Chromatographic Method for Hypericin Quantification in Nanostructured Lipid Carriers

BACKGROUND

Hypericin (HYP) is a natural compound widely used as a food supplement. The encapsulation of HYP into nanosystems, such as nanostructured lipid carriers (NLC), is a promising strategy for delivering this lipophilic molecule and protecting it from degradation.

OBJECTIVE

This study aims to develop and validate an analytical method to quantify the encapsulation efficiency of HYP in NLC.

METHOD

A reverse-phase high-performance liquid chromatography (HPLC) method was developed and validated according to the International Conference on Harmonization (ICH) guide Q2 (R1). NLC was prepared through the ultrasonication method, and HYP encapsulation efficiency was evaluated using the validated method.

RESULTS

Separation was achieved using an isocratic mobile phase composed of acetonitrile, methanol, and ammonium acetate buffer (10 mM, pH 5.0) (54:36:10, v/v/v) and a reverse stationary phase. The specificity, linearity, precision, accuracy, and robustness of the method were assessed and confirmed during the validation. Furthermore, the validated method was able to determine the encapsulation efficiency of HYP in NLC.

CONCLUSIONS

The HPLC method was validated, and the results indicated the ability of NLC to deliver HYP compounds for further application as a food supplement.

HIGHLIGHTS

HYP is used as a food supplement and for photodynamic therapy (PDT). The developed method was specific, linear, precise, accurate, and robust. NLCs showed a high ability to encapsulate HYP.

Facile synthesis and eco-friendly analytical methods for concurrent estimation of selected pharmaceutical drugs in their solutions: application to quality by design, lean six sigma, and stability studies

Economical, highly robust, selective, precise, and eco-friendly RP-UPLC and spectrophotometric methods were developed and validated for the concurrent estimation of selected pharmaceutical drugs represented in ceftazidime (CFZ) and pyridine (PYD) in their solutions using Agilent Zorbax SB-C18 RRHD (50 × 2.1 mm, 1.8 μm) column at flow rate 0.3 mL/min with wavelength 254 nm. Box-Behnken design (BBD) established Response surface methodology (RSM) to achieve the optimum chromatographic condition with minimal trials conducted. Three independent variables specifically acetonitrile ratio 60-70%, pH 3-7, and temperature 25-35 °C were implemented to evaluate the influences of these variables on the responses as resolution and retention time. Desirability and overlay plots were carried out to adjust the optimal condition that achieved the shortest retention time of less than 2 min and desired resolution of more than 1.5 using a mobile phase consisting of acetonitrile: purified water (70:30, v/v) at pH 5.0 adjusted by 0.1% orthophosphoric acid with the column oven temperature 30 °C and column void volume 0.46 mL. Mean centering of ratio spectra (MCR) and ratio subtraction (RS) methods were effectively applied to resolve drugs' spectral superposition at 220 nm, 255.4 nm, 260.3 nm, and 254.6 nm for CFZ and PYD, respectively. Linearity range was accomplished for UPLC, MCR, and RS methods over the concentration range of 2-100, 1-50,3-30 and 5-30 µg/mL for CFZ and PYD, respectively with correlation coefficient > 0.999 and good recovery results within 98-102%. Six Sigma methodology was achieved using the process capability index (Cpk) to compare the suggested and USP methods showing that both are highly capable with Cpk > 1.33. The proposed method was successfully validated depending on ICH guidelines and ANOVA results and applied for the accelerated stability study.

Development and Validation of Novel RP-HPLC Method for the Simultaneous Estimation of Capecitabine and Thymoquinone in the Biodegradable Nanoparticles using Full Factorial Design

An innovative RP-HPLC technique was devised to simultaneously quantify thymoquinone (TQ) and capecitabine (CAP) in newly designed polymeric nanoparticles. A unique chromatographic approach was created, optimized and validated using Design-Expert® (design of experiment) in compliance with ICH requirements. A 24 factorial design examined the influence of variables on method responses. The method found linear between 0.25 and 16 μg/mL, with an R2 value of 0.999. The detection and quantification limits for CAP were 0.05 and 0.16 μg/mL, respectively, and 0.12 and 0.38 μg/mL for TQ, respectively, and 97-100% recovery in plain drug solution and 100-102% in nanoformulation were achieved. A purposeful modification examined by analysis of variance revealed that the experimental model was significant (P = 0.0001). The total drug content in nanoformulation was 8.68 mg, and the entrapment efficiency was 84.79%. Based on the findings, it is possible to infer that the use of the Quality by Design methodology resulted in the development of a more accurate technique capable of producing consistent, dependable, high-quality data and precise in quantifying CAP and TQ in bulk and nanoparticulate systems.

Hansen Solubility Parameters and QbD-Oriented HPLC Method Development and Validation for Dermatokinetic Study of a Miconazole-Loaded Cationic Nanoemulsion in Rat Model

Miconazole (MCZ) is a potential antifungal drug to treat skin infections caused by Candida, Tinea pedis (athlete's foot fungal infection), Tinea cruris (jock itching in the groin and buttocks), and Tinea corporis (red scaly rash on the skin). The current study focused on Hansen parameter-based solvent selection (HSPiP software) and method development optimization using an experimental design tool for sensitive, accurate, reproducible, economic, rapid, robust, and precise methodology to quantify MCZ in rat plasma. Moreover, a Taguchi design was used for screening two independent factors (flow rate and ACN content). Quality by design (QbD) was employed to optimize and identify the right ratio of mobile phase composition and its impact on the peak and retention time. The elution of MCZ was achieved using methanol and acetonitrile (15:85 v/v ratio) at a retention time of 6 min and optimal flow rate (1 mL/min). Finally, the method was validated based on accuracy, precision, linearity, selectiveness, and high recovery at varied concentrations as per the International Council for Harmonization (ICH) guidelines. The method was linear (r2 = 0.999) over the explored concentration range (250-2000 ng/mL) at 270 nm detection wavelength. The optimized method was used to quantify in vivo pharmacokinetic (PK) study after transdermal application of MCZ-loaded formulations (MCNE11, MNE11, MCZ-Sol, and MCZ-MKT). HSP-oriented solvent selection and quality by design-based optimized process variables and composition in the optimized analytical methodology were quite convincing and have been a cutting-edge MCZ analysis method so far. The validated method was robust, economic, and rapid with high specificity and selectivity.

Fabrication of a Dual-Targeted Liposome-Coated Mesoporous Silica Core-Shell Nanoassembly for Targeted Cancer Therapy

Nanoparticles have been suggested as drug-delivery systems for chemotherapeutic drugs to allow for controlled drug release profiles and selectivity to target cancer cells. In addition, nanoparticles can be used for the in situ generation and amplification of reactive oxygen species (ROS), which have been shown to be a promising strategy for cancer treatment. Thus, a targeted nanoscale drug-delivery platform could be used to synergistically improve cancer treatment by the action of chemotherapeutic drugs and ROS generation. Herein, we propose a promising chemotherapy strategy where the drug-loaded nanoparticles generate high doses of ROS together with the loaded ROS-generating chemotherapeutic drugs, which can damage the mitochondria and activate cell death, potentiating the therapeutic outcome in cancer therapy. In the present study, we have developed a dual-targeted drug-delivery nanoassembly consisting of a mesoporous silica core loaded with the chemotherapeutic, ROS-generating drug, paclitaxel (Px), and coated with a liposome layer for controlled drug release. Two different lung cancer-targeting ligands, folic acid and peptide GE11, were used to target the overexpressed nonsmall lung cancer receptors to create the final nanoassembly (MSN@Px) L-GF. Upon endocytosis by the cancer cells, the liposome layer was degraded by the intracellular lipases, and the drug was rapidly released at a rate of 65% within the first 20 h. In vitro studies confirmed that this nanoassembly was 8-fold more effective in cancer therapy compared to the free drug Px.

QbD-Engineered Development and Validation of a RP-HPLC Method for Simultaneous Estimation of Rutin and Ciprofloxacin HCl in Bilosomal Nanoformulation

In the given study, a new reverse-phase high-performance liquid chromatography (RP-HPLC) method has been reported for the simultaneous estimation of ciprofloxacin hydrochloride (CPX) and rutin (RUT) using quality by design (QbD) approach. The analysis was carried out by applying the Box-Behnken design having fewer design points and less experimental runs. It relates between factors and responses and gives statistically significant values, along with enhancing the quality of the analysis. CPX and RUT were separated on the Kromasil C₁₈ column (4.6 × 150 mm, 5 μm) using an isocratic mobile phase combination of phosphoric acid buffer (pH 3.0) and acetonitrile with the ratio of 87:13% v/v at a flow rate of 1.0 mL/min. CPX and RUT were detected at their respective wavelengths of 278 and 368 nm using a photodiode array detector. The developed method was validated according to guideline ICH Q2 R (1). The validation parameters taken were linearity, system suitability, accuracy, precision, robustness, sensitivity, and solution stability which were in the acceptable range. The findings suggest that the developed RP-HPLC method can be successfully applied to analyze novel CPX-RUT-loaded bilosomal nanoformulation prepared by thin-film hydration technique.

Analytical quality by design-based RP-HPLC method for quantification of pioglitazone and candesartan cilexetil in bilayer tablet and its forced degradation studies

Aim: The current project involves developing an RP-HPLC method for simultaneous quantification of Candesartan Cilexetil and Pioglitazone based on analytical quality by design (AQbD).

Materials and methods: When analysed in the Design Expert application, the critical method parameters were systematically refined using Central Composite Design and contours were derived for significant variables. A contour plot has been used to discover the technique operable design region that governs response variation, which is then empirically tested.

Results: Successful chromatographic separation of title analytes was achieved on kromasil C18 (150 × 4.6 mm, 5 µm) column at 30 °C with mobile phase comprising 60% 20 Mm Potassium dihydrogen orthophosphate and 40% acetonitrile (v/v), isocratic elution pattern, 0.9 mL/min flow rate, and UV detection at 220 nm. The linear model for Candesartan Cilexetil was from 4 to 24 µg/ mL and Pioglitazone at 7.5–45 µg/ mL, respectively.

Conclusion: The method met all the ICH Q2 (R1) validation criteria. The current approach aided for analysing simultaneous drugs can be expanded into quantifying drugs in biological matrix predominance with maximum recovery.

Quality by Design (QbD) Based Method for Estimation of Xanthohumol in Bulk and Solid Lipid Nanoparticles and Validation

The analytical quality by design (AQbD) approach is utilized for developing and validating the simple, sensitive, cost-effective reverse-phase high performance liquid chromatographic method for the estimation of xanthohumol (XH) in bulk and nanoformulations. The Box-Behnken design (BBD) is applied for method optimization. The mobile phase ratio, pH and flow rate were selected as independent variables, whereas retention time, peak area, peak height, tailing factor, and theoretical plates were selected as dependent variables. The chromatogram of XH obtained under optimized conditions has given optimum conditions such as retention time (5.392 min), peak area (1,226,737 mAU), peak height (90,121 AU), tailing factor (0.991) and theoretical plates (4446.667), which are contoured in the predicted values shown by BBD. Validation of the method has been performed according to ICH Q2(R1) recommendations, using optimized conditions for linearity, limit of detection (LOD) and limit of quantification (LOQ), accuracy, precision, robustness and system suitability. All the values of validation parameters lie within the acceptable limits prescribed by ICH. Therefore, the developed and validated method of XH by the AQbD approach can be applied for the estimation of XH in bulk and various nanoformulations.

An analytical quality by design approach towards a simple and novel HPLC-UV method for quantification of the antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline

N-acetyl-seryl-aspartyl-lysyl proline (Ac-SDKP) is a tetrapeptide possessing anti-fibrotic, angiogenic, anti-inflammatory, anti-apoptotic, and immunomodulatory properties. Currently, the main method to quantify the peptide is liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA), both of which are labour intensive and require expensive equipment and consumables. Furthermore, these techniques are generally utilised to detect very low or trace concentrations, such as in biological samples. The use of high concentrations of analyte might overload the extraction column or the separation column in LC-MS/MS or the ELISA plates, so the response could be a non-linear relationship at high analyte concentrations. Thus, they are not ideal for formulation development where detection of dose-equivalent concentrations is typically required. Therefore, a cost-effective, simple, and accurate quantification method for the peptide at a higher concentration needs to be developed. In this study, a simple and novel HPLC-UV method is proposed and validated using an Analytical Quality by Design (AQbD) approach. The method is first screened and optimised using chromatographic responses including capacity factor, resolution, tailing factor, and theoretical plate counts, fulfilling the International Council for Harmonisation (ICH) Q2 (R1) guidelines. The resultant optimised chromatography conditions utilised 10 mM phosphate buffer at pH 2.5 and acetonitrile as mobile phases, starting at 3% (v/v) acetonitrile and 97% (v/v) buffer and increasing to 9.7% (v/v) acetonitrile and 90.3% (v/v) buffer over 15 minutes at a flow rate of 1 mL/min at the column temperature of 25 °C. The injection volume is set at 10 μL and the VWD detector wavelength is 220 nm. The method established is suitable for detecting the peptide at a relatively high concentration, with a quantifiable range from 7.8 μg/mL to 2.0 mg/mL. In addition, the use of a relatively simple HPLC-UV approach could significantly reduce costs and allow easier access to quantify the peptide concentration. A limitation of this method is lower sensitivity compared with using LC-MS/MS and ELISA methods but running costs are lower and the methodology is simpler. The method is capable to quantify the peptide in various tested matrix solutions, with successful quantitation of the peptide in samples obtained from in vitro drug release study in PBS and from a chitosan-TPP nanogels formulation. Therefore, the method developed here offers a complementary approach to the existing quantification methods, quantifying this peptide at increased concentrations in simple to intermediately complex matrix solutions, such as HBSS, DMEM and FluoroBrite cell culture media.

Box-Behnken Design (BBD) Application for Optimization of Chromatographic Conditions in RP-HPLC Method Development for the Estimation of Thymoquinone in Nigella sativa Seed Powder

Thymoquinone (THY) is a bioactive compound present in the seed powder of Nigella sativa (NS). This research aims to precisely and accurately estimate THY using high-performance liquid chromatography (HPLC) with a Quality by Design (QbD) application. Box-Behnken design (BBD) was employed to optimize the chromatographic conditions for HPLC method development, taking mobile phase flow rate, pH of the buffer, and λmax as independent variables and retention time and tailing factor as the measured responses. The mobile phase composition was methanol: acetonitrile: buffer (2.2 mM ammonium formate) at the ratio of 35:50:15 v/v/v on a Symmetry® C18 (5 μm, 3.9 × 150 mm) column. In isocratic mode, it had a flow rate 0.9 mL min−1 and eluted analyte was detected at 249 nm. Validation parameters followed the International Council for Harmonization (ICH) guidelines for the new HPLC method. The method was linear over the range 6.25–100 µg mL−1 with a coefficient of determination (r2) of 0.9957. The limit of detection (LOD) and limit of quantification (LOQ) were 2.05 and 6.25 µg mL−1, respectively. The %RSD of system suitability for retention time was 1.42% and for the tailing factor it was 0.695%. In addition, the developed method was precise, accurate, and robust according to ICH criteria. The developed HPLC method is simple, accurate, quick, and robust, and it could be used for the routine analysis of THY in different kinds of formulations.