Objective: Simple, sensitive, precise, reproducible, and validated visible spectrophotometric methods have been developed for the determination of leukotriene receptor antagonist drug, namely, montelukast (MNT) sodium in bulk and pharmaceutical preparations. Methods: Three spectrophotometric methods are based on the formation of yellow-colored ion-pair complexes between MNT sodium and three dyes, bromocresol green, bromophenol blue, and methyl orange with absorption maxima at 420, 416, and 426 nm, respectively. Results: The stoichiometric ratio of the formed ion-pair complexes was found to be 1:1 (drug:reagent) for all methods, as deduced by Job’s method of continuous variation. Several parameters such as pH, buffer type and volume, reagent volume, sequence of addition, and effect of extracting solvent were optimized to achieve high sensitivity, stability, low blank reading, and reproducible results. Under the optimum conditions, linear relationships with good correlation coefficients (0.9993–0.9999) were found over the concentration ranges of 1.0–10, 1.0–12, and 1.0–16 μg/mL with a limit of detection of 0.30, 0.29, and 0.27 μg/mL for bromocresol green, bromophenol blue, and methyl orange methods, respectively. Conclusion: The proposed methods were validated in accordance with ICH guidelines and successfully applied to the analysis of MNT sodium in pharmaceutical formulations. Statistical comparison of the results obtained by applying the proposed methods with those of the reference method revealed good agreement and proved that there was no significant difference in the accuracy and precision between the results.

Green, rapid and modified surface-active ionic liquid assisted cloud point extraction method (SAIL-CPE) was developed to preconcentrate trace levels of nickel Ni(II) ions in environmental samples perior to its detection by FAAS. The proposed method based on utilizing a mixture of a nonionic surfactant (Triton X-114) and a surface-active ionic liquid, 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl), as an extracting phase for Ni(II) ions after the complexation with sunset yellow FCF at pH 6.5. The impact of different analytical parameters on improving the extraction efficiency was invistigated. In the range of 2.0-600 µg L−1, the calibration graph was linear with correlation coefficient of 0.9998. Limit of detection and preconcentration factor were 0.6 and 100. The reliability and precision of the proposed SAIL-CPE system as the relative standard deviation (RSD %) in the presence and absence of SAIL were examined by applying ten replicate determinations of 300 µg L-1 of Ni(II), and RSD % of the recoveries were found to be 1.40 and 2.9%, respectively. The validation of the proposed procedure was verified by test of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SRM spinach leaves 1570A) applying the standard addition method. Finally, the proposed SAIL-CPE method was developed and applied to preconcentrate and determine of trace levels of Ni(II) ions in real water, food and tobacco samples with satisfactory results.

Background: Cadmium (Cd2+) and lead (Pb2+) have acute and chronic effects on humans and other living organisms. In the present work, new, green and accurate dispersive micro solid-phase extraction (DμSPE) method for the separation and preconcentration of trace amounts of cadmium (Cd2+) and lead (Pb2+) ions in various food, water and tobacco samples collected from Saudi Arabia prior to its Flame Atomic Absorption Spectrometric (FAAS) determinations was developed. Methods: The proposed method was based on a combination of oxidized multiwalled carbon nanotubes (O-MWCNTs) with a new chelating agent 5-benzyl-4-[4-methoxybenzylideneamino)-4H- 1,2,4-triazole-3-thiol (BMBATT) to enrich and separate trace levels of Cd2+ and Pb2+. The effect of separation parameters was investigated. The validation of the proposed preconcentration procedure was performed using certified reference materials. Results: Analyte recovery values ranged from 95-102%, indicating that the method is highly accurate. Furthermore, precision was demonstrated by the relative standard deviation (RSD < 3.0%). The limits of detection were 0.08 and 0.1 μg L−1 for Cd2+ and Pb2+ ions, respectively. The preconcentration factor was 200. Conclusion: The proposed method was used for the estimation of Cd2+ and Pb2+ ion content in various real samples, and satisfactory results were obtained. The proposed method has high adsorption capacity, rapid adsorption equilibrium, extremely low LODs, high preconcentration factors and shortens the time of sample preparation in comparison to classical SPE.