Colorimetric Determination of Phenylephrine hydrochloride Drug by Diazotization Reaction

By diazotization coupling reaction is one of the most frequently employed technique in pharmaceutical analysis. It involves measuring the amount of ultraviolet or visible radiation absorbed by a substance in solution as a method for estimation drug of Phenylephrine hydrochloride by reliant on azo-coupling reaction between (PHE)HCl and Clonazepam as a reagent. To reach to the aim of obtaining the colored product with a maximum absorbance 466nm. The linearity range for Phenylephrine hydrochloride was (0.5_9μg\ml) while the detections limit 0.006 and quantification limit 0.02μg\ml The Molar Absorptivity 2.5457 ×104L/mol.cm with Sandal’s sensitivity 0.01μg\cm2. Eventually these methods were successfully completed to determination of PHE.HCl in pure and commercial form.

Spectroscopic analysis is commonly carried out in solutions but solids and gases may also be studied. The development of the instrumental analysis had an important effect to improve the methods of analyzing drug compounds, as well as in the standards used by the manufacturers of drugs. The most important of these methods are [5] include: Chromatography[6] which is most frequently used in pharmaceutical analysis by its ability to achieve high-resolution separation and it is include: chromatography [7],Column Ion-excchromatographyhange Gel-permeation (molecular sieve) chromatography [8]Affinity chromatography [9],Paper chromatography [10], Thin-layer chromatography [11], Gas chromatography (GS) [12], Dye-ligand chromatography [13], Hydrophobic interaction chromatography [14] ,Pseudo affinity chromatography [15],High-pressure liquid chromatography (HPLC) [16] .These methods required to use very accurate concentrations and high purity, In other hand the application of electrochemical techniques [17] in the analysis of drugs and pharmaceuticals has increased greatly over the last few years .An azo coupling [4] is an organic reaction between a diazonium compounds and another aromatic compound that produces an azo compound. In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the electrophile and the activated arene is a nucleophile. In most cases, including the examples below, the diazonium compound is also aromatic. The process of conversion of primary aromatic amines into its diazonium salt is called Diazotization [18]. Diazonium salts are important synthetic intermediates that can undergo coupling reaction to form azo dyes and electrophilic substitution reaction to introduce functional groups. .Phenylephrine hydrochloride (PHP), [(R)1-(3hydroxyphenyl).2-(methylamino) ethanol hydrochloride], is a white crystalline powder, and belongs to the group of medicines called sympathomimetics [19,20]. It acts stimulating the alpha receptors in certain areas of the body. It is used locally, as decongestant, for nonspecific and allergic conjunctivitis, sinusitis and nasopharyngitis [21]. PHP nasal drops [22] are used for treating symptoms such as runny nose, sneezing, itching of the nose and throat. Phenylephrine Hydrochloride has molecular weight equal to 203.66 g/mol shown in figure (1)   Hydrochloric acid 1M: it was provided by from (GCC) at 98% prepared by diluting appropriate concentration hydrochloric acid at 25ml distilled water.

Procedure:
In the series of calibrated flask of 10ml aliquots 0.2ml from HCl (1M) with 0.6ml of (0.1M) Sodium Nitrite, add 1ml from Clonazepam drug (0.001)M as a reagent and then add 0.6ml from Sodium Nitrate. Wait for (10min) in order to complete the (azocoupling) reaction successively after that 1.2ml from ammomiumhydroxide (4M) and 0.5ml from PHE.HCl and complete with distilled water to the mark of calibrated flask. The obtained solutions can be sitting stable for (60 min) at room temperature and absorbance 466nm was measured versus blank reagent.

Procedure for Pharmaceutical Preparations
Nasal drop (Nasophrine): Take 4ml from Nasophrine contain 10ml with concentration (0.25g/100ml) and dilute volume in volumetric flask 100ml to the volume mark.

RESULTS AND DISCUSSION
In the procedure, effects of different parameters on color characteristics for azo dye by gain optimum conditions reaction.

Effect of Acid Volume
To be sure through experiment of existence effect acid on the absorbance product, using hydrochloric1M with series different volumes (0.1-1ml).0.2ml from acid give the perfect absorbance. Figure (

Effect of Sodium Nitrite Volume
Series of different volume (0.2-1.2 ml) from Sodium Nitrite (0.1M) and found that the perfect absorbance obtain at 0.6ml of Sodium Nitrite while the best time (5min) that enough the result colored intenseness have been for complete diazotization of PHE.HCl.

Effect of Reaction Time
To be sure effect on the stable intense colored prepared phenylephrine hydrochloride with Clonazepam under the perfect conditions and measured at different intervals time approachat 60 min the result obtain refer to that the color intensity improve and stay constant at least 60 min [24].as shown in Fig (6)

Absorption Spectra
The reaction of Phenylephrine hydrochloride with Clonazepam under optimum conditions give orange intense color as product at maximum wave length 466nm while solution blank colorless absorption as shown in Fig (7) 1st

Application
The suggested method is applying for determination Phenylrphrine hydrochloride in Nasophrine (Nasal drop) the results explain in Table (1) show values of a good recovery obtainable, The proposed method scored more successfully and effectively for the standard method as appear in Table(3).

CONCLUSION
A precise, simple and accurate spectrophotometric method have been improved investigation of trace an amount of PHE. HCl adopted on (diazotization -coupling) reaction with Clonazepam with present of sodium nitrate (0.01M) ,(1M) HCl and Ammonium hydroxide in pure and doses forms.