Available online on www.ijddt.com International Journal of Drug Delivery Technology 2019; 9(2); 182-192 doi: 10.25258/ijddt.9.2.11 ISSN: 0975 4415 Research Article Spectrophotometric Determination Methyldopa and Salbutamol by Oxidative Coupling, Cloud Point and Flow Injection in Pharmaceutical Formulations Nisreen Kais Abood1*, Mohammed Jasim M Hassan1, Muneer A AL-Da,amy2 1Department of Chemistry, College of Science, Mustansiriyah university Baghdad, Iraq 2Department of Chemistry, College of Education for pure Science, Karbala University, Kerbala Iraq Received: 21st Jan, 19; Revised: 2nd Apr, 19, Accepted: 14th May, 19; Available Online: 25th Jun, 2019 ABSTRACT Three methods study in this research simple, sensitive, an expensive and rapid Oxidative Coupling reaction, Cloud Point Extraction and Flow Injection spectrophotometric methods for determination Methyldopa and Salbutamol, the first method oxidative coupling reaction between the Methyldopa and thiosemicarbazide in presence of ferric nitrate anhydrous to yield dark green colored product that have absorbance at λ max 460 nm. Salbutamol coupling reaction with 4-nitrophenyl hydrazine in presence the potassium Iodide and sodium hydroxide to product the violet colored has absorbance at λ max 530 nm. Beer’s law is obeyed from (1-50) µg/ mL with sandall’s sensitivity (0.039,0.073), correlation coefficient (0.9998) and molar absorptivity (0.536×104,0.327×104) for Methyldopa and Salbutamol respectively. The secondly method to estimation the trace amount of phenolic drugs that product from the oxidative coupling reaction it is cloud point extraction, cloud point extraction enables the drugs to be precisely estimated under the optimal experimental conditions, the maximum absorption at λ max (470,535) nm respectively. The concentration was range (0.25-6) µg/mL, molar absorptivity 0.510×105,0.483×105 and enrichment factor (9.51,14.72) respectively for Methyldopa and Salbutamol .Flow injection analysis is simple method to determination the phenolic is based on the measurement of absorption signal for product resulting from oxidative coupling reaction , study all experimental parameters chemical and physical to development and stability the colored of product .Total flow injection of 1.5mL/min was pumped and active material was detect at λ max (460,530)nm respectively for Methyldopa and Salbutamol . In this the proposed methods were suxciffuly, applied to the determination Methyldopa and Salbutamol in pharmaceutical preparation. Keywords: Oxidative Coupling, Phenolic Drugs, Flow Injection, Cloud Point Extraction, Spectrophotometric. INTRODUCTION spectrophotometric method12. Oxidative Coupling Methyldopa is (β-3,4-dihydroxy phenyl-α-methyl alanine reaction its reaction between two or more from organic MD), It’s a white to yellow-white powder or almost compounds in presence of oxidant agent and the color colorless, soluble in warm distilled water1,2, Methyldopa product can be determining by different methods such as have various pka value depend on the functional group spectrophotometric, polar graphic and 13,14 that found in the structure such as –NH2, -OH and chromatographic , oxidative coupling are applied COOH3,4 the structure fig.1, several methods to successfully in many fields such as pharmaceutical estimation Methyldopa in pharmaceutical preparation agricultural15. Cloud Point Extraction (CPE) it’s titrimetric method, fluorimetry, kinetic measurement, introduced by watanbe and tanaka in 197816,CPE used to potentiometric and flow injection method5,6. Salbutamol estimation various trace metals and drugs, the having Sulfate (SBS) as (rs)-1-(4-hydroxy3- considerable advantages such as simplicity cheapness, hydroxymethylphenyl)-2-(tert-butyl amino) ethanol fast selectivity ,high enrichment factor and low toxicity to sulfate, the salbutamol also known albuterol7 fig. 2. the environment than other extraction method that used Salbutamol is acted as it cardiovascular and the best organic solvents17,18.Flow injection it’s best bronchodilator in fluencies are smaller than it technique characterized as simple, cheap, fast and bronchodilator action drugs which is a common entity in selectivity to estimate the drugs19,20, Flow injection high performance8. Salbutamol is prevalently used by analysis (FIA) system have many interest such as athletes, anti-doping agent9, Salbutamol in increase sample throughput, low reagent consumption, pharmaceutical used in various way to estimation reduce waste production, and inexpensive equipment21,22. oxidative coupling, diazotization and coupling10, intrastation, nitration, charge transfer11, HPLC, EXPERIMENTAL Electrophoresis, Gas chromatography and Instruments *Author for Correspondence: [email protected] Nisreen et al. / Spectrophotometric Determination Methyldopa… Figure 1: Methyldopa Figure 2: Salbutamol SX Thiosemicarbzade pump Ferric nitrate W R.C FC D Figure 3 Figure 4 Figure 3,4: Scheme of employed flow system, P: peristaltic pump, R.C: reaction coil, S: sample injection, W: waste, FC: flow cell Figure 5: Absorption spectrum of oxidative coupling for methyldopa with the reagent against the reagent blank under optimum conditions. Figure 6: Absorption spectrum of oxidative coupling for Salbutamol with the reagent against the reagent blank under optimum conditions. All spectral and absorbance measurement were carried in 7110 and Electronic Balance Mettle AE 200. The Flow signal beam UV Visible spectrophotometer 160. injection configuration A three channel manifold Fig.3 Equipped with 1cm and 0.5 cm quarts’ cell. An for Methyldopa and Fig.4 for Salbutamol was employed Ultrasonic and thermostatic water bath from Elma Hans for (FIA). Peristaltic pump (ALITEA, C4, made in Schmidbauer Gmbh and Co.KG used coupled with Sweden) with polyvinyl chloride tube (0.8) mm internal Extraction of samples. A centrifuge (Shanghai surgical diameter was used for the peristaltic pump and Reaction instrument factory,80-2, Shanghai, Germany) that use to Coil complete the separation of CPE, PH meter, type inoLap Reagents IJDDT, April 2019 – June 2019, Volume 9, Issue 2 Page 183 Nisreen et al. / Spectrophotometric Determination Methyldopa… Table 1: Effect order addition. No. order Order addition of Absorbance of Order addition of Absorbance of Methyldopa Methyldopa salbutamol Salbutamol 1 O+R+D 0.067 R+O+D+B 0.089 2 O+D+R 0.084 R+O+B+D 0.090 3 R+D+O 0.133 R+D+O+B 0.512 4 D+R+O 0.879 D+R+O+B 0.322 5 R+O+D 0.341 D+O+R+B 0.311 D=Drug, R=Reagent, O=Oxidant, B=Base Table 2: Characteristic parameter for the regression The best method was developed to prepared oxidative equation of the proposed oxidative coupling method coupling reaction of Methyldopa by adding 1mL ,1000 for methyldopa and salbutamol. μg/mL Methyldopa,1mL ,1000 μg/mL thiosemicarbazide Parameter Methyldopa Salbutamol and 1mL (0.1) M Fe(NO3)3.9H2O, that gave the dark λ max(nm) 460 530 green colored at λ max (460) nm. Salbutamol (1ml,1000 color Green Violet μg/mL coupling with 1 mL ,0.2 M 4-nitrophenyl linearity range μg/mL 1-50 1-50 hydrazine, 1 mL, 0.1 M KIO3 in presence 0.5ml ,1M 4 4 Molar absorptivity 0.536×10 0.327×10 NaOH that gave violet colored at λ max (530) nm, finally (L.mol-1.cm-1) placed in 20 mL flask complete with distilled water. The Sandell’s sensitivity 0.039 0.073 oxidative coupling formed absorbance dark green, violet 2 (μg/cm ) colored at λ max (460.530) nm for Methyldopa and Correlation coefficient 0.9998 0.9998 Salbutamol respectively. ® General Procedure of Cloud Point Extraction for Regression equation Y=0.0254x Y=0.0137x- Phenolic Drugs - 0.0223 0.0065 The various concentration (0.25-6) μg/mL from the dye of Slope(b) 0.0254 0.0137 oxidative coupling reaction result transfer 1mL from this Intercept(a) -0.0223 -0.0065 product into 15mL of centrifuge tubes ,10% v/v Triton X- Analytical sensitivity 0.065 0.064 114 1 mL add, 2 mL of 0.01 M of surfactant (CTBA) , 2 -1 (μg.ml ) mL from 5% Na2SO4 respectively, after that complete the Limit of detection 0.118 0.218 volume 12.5 mL with distilled water. Test tube put into (μg/mL) ultrasonic thermostatic water bath let it 2 mint to mix the Limit quantification 0.389 0.729 mixture and water bath 40,50ºC for 50 min. Formation μg/mL Cloudy and it is separation into two phase after that C.L. for the 0.0254±0.0 0.0137±0.00 transfer to centrifuge to complete separation two-layer slope(b±tsb)at 95% 00968 05472 organic phase and aqueous phase, decant the aqueous and C.L. for the - - add 0.5 mL ethanol to organic phase to dissolve the dye. intercept(a±tsa) at 95% 0.0223±0.0 0.0065±0.01 1cm cell was used to determination the dye, prepared the 1984 124 blank under in the same way. Standard error for 0.005612 0.00318 General Procedure of Flow Injection regression line (S y/x) A Methyldopa and Salbutamol solution was prepared by different concentration 1-150 μg/mL from the standard All Chemicals were analytical grade. stock solutions working solution 1000 μg/mL. A 100µL portion (1000 μg/mL) Methyldopa and Salbutamol were prepared Methyldopa was injected into stream of 0.2 M by dissolving 0.1 gm of Methyldopa and Salbutamol in thiosemicarbazide the mixture reacted with stream -2 distilled water and dilution to the mark in 100mL (1.5×10 ) M Fe(NO3)3.9H2O, the reaction is carryout via volumetric flask. Stock solution of thiosemicarbzide mixed well in 50 cm reaction coil Figure3. Salbutamol (1000 μg/mL) were prepared by dissolving 0.1 g of 100µL was injected into carrier stream which product thiosemicarbazide in distilled water and dilution to the from mixing three channel the first channel carrier (0.2) mark in 100mL volumetric flask. M 4-nitrophenyl hydrazine the mixed react with oxidative -preparation 1 M NaOH was prepared by dissolving 10 g agent 0.1 M KIO3, then the mixture reacts with third of NaOH in 250 mL distilled water, 4-nitro phenyl channel stream 2 M NaOH the product carryout via hydrazine 0.2M was prepared by dissolving 3.06g in 2mL mixed well 50 cm reaction coil Figure4, the resulting of of concentrated Sulfuric acid in 100mL distilled water, Methyldopa and Salbutamol dark green and violet at λ max 0.1 M KIO3 was prepared by dissolving 2.14 g of KIO3 in (460 ,530) nm respectively.