A simple and sensitive spectrophotometric method for the quantitative determination of trace amounts of oxymetazoline hydrochloride (OMZ) was developed .The method based on the reaction of (OMZ) with Fe(III) in acidic medium.The librated Fe(II) coupled with potassium ferricyanide, the reaction needs heating for 25 minutes at 50 o C, to form Prussian blue which is more stable by adding 1ml of 1% ethylendiaminetetraacetic acid. The maximum absorption of the product was measured at 766 nm .Beer ' s law is obeyed in the concentration range 5-125 µg/10ml with a molar absorptivity of 5.07x10 4 l. mol-1 .cm-1 ,with a relative error of +1.74 to +2.34 % and a relative standard deviation (RSD%) of the of ±1.272 to ±1.982 %.The method was applied successfully for the assay of OMZ in pharmaceutical preparation.
A simple, rapid and sensitive spectrophotometric method is proposed for the determination of niclosamide (NIC) in pure form and in its pharmaceutical preparations. The method is based on the reduction of niclosamide by zinc powder in acidic medium followed by the diazotization of reduced niclosamide, then coupling with 2,6dihydroxybenzoic acid to give a yellow colored product which is water-soluble and has a maximum absorption at 456 nm with a molar absorptivity of 2.36×10 4 l.mol-1. cm-1. The color reaction is highly stable and does not show a significant change in absorbance up to 24 hours. Beerُ ُ s law is obeyed in the concentration range of 5-300 µg of niclosamide in a final volume of 10 ml. The method has been successfully applied to the determination of niclosamide in tablets.
The infrared technique is one of the oldest techniques; it deals with the frequencies of bond vibration in a molecule. The main uses of this technique are to identify and determine components in various organic or inorganic compounds. In this technique, a part of the incident infrared radiation is absorbed by the molecules of the sample and the other is transmitted. The favorite method of infrared spectroscopy is FTIR (Fourier transform infrared). There have been many developments in using IR technique in qualitative and quantitative analyses, including the first and second derivatives of the infrared spectrum. IR rays do not damage the exposed skin like other rays such as ultraviolet light. It must be mentioned that the IR technique was used in hyphenated techniques (instead of the detector in chromatographic device), for example, after separation by gas chromatography detected by IR. Also, this chapter contains essential information about Raman spectroscopy. Infrared spectroscopy is a technique that has acceptable accuracy and sensitivity to be one of the most important analytical techniques used in the qualitative analysis, and also, it is used in the quantitative estimation of compounds through measuring the transmitted or absorption intensity of the active groups.
A simple and sensitive indirect spectrophotometric method is developed for the determination of niclosamide in pharmaceutical preparations. The method is based on the oxidation of reduced form of niclosamide with iron ( III ) in acidic medium, then the subsequent reaction of iron ( II ) with 1,10phenanthroline to produce a ferroin complex which is water -soluble , stable (using EDTA solution improve the stability of the complex) , and has a maximum absorption at 510 nm against the reagent blank with a molar absorptivity of 2.19×10 4 l.mol -1 .cm -1 . Beer , s law is valid over the concentration range of 2.5 to 225 µg/10 ml. The relative error is in between -1.80 and +1.50 % and the relative standard deviation from ± 0.89 to ± 2.07 % depending on the concentration of niclosamide . The proposed method has been applied successfully to determine niclosamide in pharmaceutical preparations.
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