Sensitive Spectrophotometric Determinations of Paracetamol and Protriptyline HCl Using 3-Chloro-7-hydroxy-4-methyl-2H-chromen-2-one

A new spectrophotometric method is developed for the determination of Paracetamol (PCT) and protriptyline HCl (PTP) in pure forms and in pharmaceutical formulations. The experiment involves the use of 3-chloro-7-hydroxy-4-methyl-2H-chromen-2-one as a novel chromogenic reagent for the determination of PCT and PTP. The method is based on the formation of charge transfer complex between the drugs and chromogenic reagent. Beer's law is obeyed in the concentration ranges 10.00–60.00？μg？mL？1 for PCT at 545？nm and 40.00–160.00？μg？mL？1 for PTP at 468？nm. The molar absorptivity, Sandell, sensitivity, and limit of detection and quantification are also calculated. The method has been successfully applied for the determination of both PCT and PTP in pharmaceutical samples with acceptable results. 1. Introduction Paracetamol (PCT), N-(4-hydroxyphenyl)ethanamide is one of the most commonly used home medicine to reduce pain and fever [1] (Figure 1). These actions are known, respectively, as analgesic and antipyretic [2]. PCT is also used to treat headache, muscle ache, arthritis, backache, toothache, cold, and fever. An overdose of PCT may cause some toxic effects such as fulminating hepatic necrosis, which causes about 450 deaths in the USA every year [3]. Thus, the development of simple methods for the determination of PCT is obviously significant in pharmaceuticals. Figure 1: Paracetamol. Protriptyline HCl (PTP) is one of the tricyclic antidepressant [4], chemically known as N-methyl-5H-dibenzo[a,d]-cycloheptene-5-propanamine hydrochloride (Figure 2). It works by blocking the transporters responsible for reuptake of neurotransmitters like norepinephrine and serotonin [5]. This medication is primarily used to treat the anxiety, depression, bipolar disorder, and obsessive-compulsive disorder [6]. They are also known as effective analgesic used for the treatment of chronic pain especially neuropathic or neuralgic pain [7]. Figure 2: Protriptyline HCL. A number of methods are available in the literature for the determination of PCT, such as high-performance liquid chromatography [8–10], Chemiluminescence [11], Fluorescence [12], pulse perturbation technique [13], Spectrofluorimetric [14], and several others. A very few methods are reported in the literature for the determination of PTP in pharmaceutical formulations which include high performance liquid chromatography [15–17], Liquid chromatography [18], and flow injection technique [19]. Above mentioned techniques are not widely used in the basic clinical laboratories, because they require more expensive equipments