The developed analytical method was validated with respect to specificity, linearity, precision, accuracy, robustness, selleck compound limit of detection (LOD) and quantification (LOQ). The stability of duloxetine samples was also studied. These studies were performed in accordance with established ICH guidelines. MATERIALS AND METHODS Chemicals and reagents The certified duloxetine hydrochloride, the working standard was supplied by Dr. Reddy’s Laboratories limited, Hyderabad, India. The HPLC grade acetonitrile and analytical grade KH2PO4 and ortho-phosphoric acid were purchased from Merck, Mumbai, India. High purity water was prepared by using Millipore Milli-Q Plus water purification system (Millipore, Milford, MA, USA). Swabs for sampling were purchased from ITW Texwipe (Philippines).

Apparatus The chromatography analysis was performed using a Waters Acquity? UPLC separation module (Waters Corporation, Milford, USA) equipped with a UV/visible detector, binary solvent manager and auto sampler system. The output signal was monitored and processed using Empower 2 software. The pH of the solutions was measured by a pH meter (Mettler-Toledo, Switzerland). In the sample preparation, an ultrasonic instrument was used for sonication. Chromatographic conditions The method was developed using an Acquity UPLC? HSS T3 (100 �� 2.1 mm2) 1.8 ��m column with an isocratic mobile phase containing a mixture of 0.01 M potassium dihydrogen ortho-phosphate, pH adjusted to 3.0 with ortho-phosphoric acid and acetonitrile (60:40 v/v). The mobile phase was filtered through nylon 0.22 ��m membrane filters and degassed.

The flow rate of the mobile phase was 0.4 mL/min. The column temperature was maintained at 40 ��C and the eluted compounds were monitored at the wavelength of 230 nm. The sample injection volume was 5 ��l. Standard solution preparation Milli-Q water and methanol in the ratio of 10:90 v/v was used as diluent. A stock solution containing 0.56 mg/mL duloxetine was prepared by an dissolving appropriate amount of drug in diluent. The final concentration of solution was 0.1 ��g/mL of duloxetine. Appropriate dilutions were made with diluent to obtain solution containing 0.5, 1.0, 5.0, and 50 ��g/mL. Sample preparation (extraction procedure) The selected surfaces (25 �� 25 cm2) of stainless steel, previously cleaned and dried, were sprayed with 1000 ��L of standard solution, for the positive swab control at all concentration levels and the solvent was allowed to evaporate.

The total surface were successively wiped first in horizontal and secondly in a vertical way, starting from outside toward the center, with one or two swabs moistened with extraction solution (water�Cmethanol 10:90, v/v) to remove the residue from the surface. The swabs were placed in the 25 mL screw-cap test tubes containing 10 mL extraction Dacomitinib solution.