Sensitive Analytical Liquid Chromatography-Tandem Mass Spectroscopy Method for the Estimation of Dexlansoprazole in Pharmaceutical Formulations

© 2018 Rinchi Bora et al. This is an open access article distributed under the terms of the Creative Commons Attribution License -NonCommercial-ShareAlikeUnported License (http://creativecommons.org/licenses/by-nc-sa/3.0/). *Corresponding Author S.N. Meyyanathan, Department of Pharmaceutical Analysis, JSS College of Pharmacy, Ootacamund, (JSS Academy of Higher Education and Research, Mysuru)-643 001, India. E-mail: snmeyyanathan @ jssuni.edu.in Sensitive Analytical Liquid Chromatography-Tandem Mass Spectroscopy Method for the Estimation of Dexlansoprazole in Pharmaceutical Formulations

The literature survey revealed a stability method and an analytical method for Dexlansoprazole (DLP) was estimated by HPLC (Hotha et al., 2012;Sriharshaet al., 2015;Yanamadala et al., 2013) and to best of our knowledge, liquid chromatographytandem mass spectroscopy has been previously reported in human plasma.
The aim of the current study was to develop a highly sensitive method for the estimation of Dexlansoprazole bulk and formulations and validate as per ICH guidelines (ICH, 1996).

Materials
Working standard of Dexlansoprazole was provided as a gift sample from Indian Pharmacopoeia Commission, New Delhi, India and internal standard Omeprazole was purchased from Drugs testing laboratory, JSS College of Pharmacy, Ooty, India.Acetonitrile of LC-MS/MS grade by Sigma Aldrich, Ammonium Acetate by Rankem Fine Chemical Limited and Water of LC-MS/ MS grade from Milli-Q RO system (Millipore, Bedford, USA) were used.

Equipment and chromatographic conditions
LC system coupled with tandem quadrupole mass spectrometry (Shimadzu 8030, Tokyo Japan) equipped with electrospray ionization (ESI) interface, LC-20AD pump, SPD-M20 PDA detector, CTO-20AC column oven, CBM-20 alite controller and SIL-20AC autosampler was used.The data were recorded using Lab solution data station software.Isocratic separation was achieved using Zorbax SB C 18 column (4.6 × 50 mm, 3 µm) as a stationary phase and the mobile phase consists of (0.5 mM) Ammonium acetate (pH 3.5): acetonitrile (30:70 V/V) with a flow of 0.5-mL/min and injection volume of 10 µl was employed.

Selection of a mass range
A 1000 ng/mL of Dexlansoprazole and Omeprazole was infused into the mass spectrometer directly and the conditions for the operation were optimized.Obtained transitions were 255→237.1 and 195→138.1 m/z was used to monitor Dexlansoprazole and Omeprazole (IS) (Figure 2b).

Preparation of working standard solution
Dexlansoprazole was dissolving in 10 mL of acetonitrile to produce a concentration of 1 mg/mL.The stock solution was refrigerated at 2-8°C and stored.Further, the working solutions were obtained by diluting the stock solution with diluent acetonitrile.

Preparation of working omeprazole solution (IS)
Omeprazole solution was dissolving in 10 mL of acetonitrile to produce a stock solution of 1 mg/mL.The stock solution was refrigerated at 2-8°C and stored.Further, working solutions were obtained by diluting the stock solution with diluent acetonitrile.

Preparation of sample solution
Dexlansoprazole equivalent to 0.10 g was taken in a volumetric flask and dissolved in methanol and marked up with acetonitrile to get 10 µg/mL.Further dilution of the above solution with the diluent acetonitrile to produce the concentration of 15, 750, 2500 ng/mL (LQC, MQC, and HQC).

Method validation
Validation of the method for specificity, linearity, accuracy, precision, range, quantitation limit, and detection limit, robustness, and system suitability as per the ICH guidelines (ICH, 1996).

Specificity
The analyte response measurement in the presence of other drugs, excipients, and their potential impurities can be termed as specificity.

Linearity
The average of six determinations at ten concentration levels covering the range of 0.5-3000 ng/mL for DLP, the evaluation of linearity was performed.Calculation of the coefficient correlation, slope and intercept values was done by using calibration curve for linearity evaluation.

Accuracy
The accuracy of the method was determined by recovery studies according to ICH guidelines.The pre-analyzed samples were spiked with standard drug DLP.

Precision
Evaluation of precision was carried out by inter-day and intra-day precision.Study samples consisted of three concentration levels (six replicates) of low (LQC), medium (MQC) and high (HQC) quality controls, i.e. 15, 750, 2500 ng/mL, respectively.The report used for precision was from the regressed concentration of the percent relative standard deviation (%RSD).

Limit of detection (LOD) and limit of quantification (LOQ)
Determination of LOD and LOQ was by the signal-tonoise ratio.LOD ratio was 3:1 whereas LOQ, the drug could be quantified with minimum peak area in the ratio of 10:1.

Robustness
The alteration in the condition of the experiment like operators, the source of reagents, similar type column and optimized conditions like pH, mobile phase ratio, and flow rate were studied for the robustness of the method.

System suitability
For method development, the test for system suitability is an integral part.Three replicates injections of the sample solution were evaluated for retention time (RT), a number of theoretical plates (N) and Tailing factor (T).

Specificity
To determine that the excipients used are not interfering with the main compound peak, test for specificity needs to be done.No peaks were eluted along with the retention time of DLP (Figure 2a).Hence, the developed method results showed that it was selective for determination of DLP in the formulation.

Calibration curve
The evaluation of the method to be linear was by six determinations at ten concentration levels with a range of 0.5-3000 ng/mL for DLP and the standard deviation (SD) were found to be within the limits.A calibration curve was found to be linear with a mean regression of equation (Y = 15.944x+ 538.34, r 2 = 0.99942, S.D. = 0.68) respectively, where the analyte peak area ratio to the IS (Omeprazole) is the Y and the analyte concentration in ng/mL is the X (Figure 3).

Accuracy
The accuracy of the method was carried out for three quality control (LQC, MQC, and HQC) samples by standard addition method, and the accuracy was found to be 96.00 to 99.83%.Application of the developed method for the estimation of a commercial formulation of DLP (Table 1).

Precision
The precision of the method was determined by the intraday and inter-day precision studies at three different concentrations and they were found to be within the limits (Table 1).

Fig. 2 :
Fig. 2: (a) Typical HPLC chromatogram of dexlansoprazole in the formulation and (b) Typical LC-MS/MS chromatogram of dexlansoprazole in the formulation.

Table 1 :
Accuracy and precision studies for the determination of Dexlansoprazole.

Table 2 :
Recovery studies for formulation.