Spectrophotometric determination of acrivastine in urine and capsules

Three sensitive and accurate spectrophotometric methods are presented for the determination of the antihistaminic acrivastine (ACR) in capsules and urine. The first method utilizes the reaction of 2-nitrophenylhydrazine hydrochloride in presence of dicyclohexylcarbodiimide and pyridine. The violet colour of the resulting acid hydrazide is measured at 550 nm. The second method is based on alkaline oxidation of the drug with potassium permanganate and subsequent measurement of the formed manganate ion at 608 nm. The third method uses derivative spectrophotometry for the determination of ACR. The last method is extended to the in vitro determination of the drug in urine. All methods gave a relative standard deviation of less than 2%.     

Colorimetric and Spectrofluorimetric Methods for the Determination of Melatonin in Tablets and Serum

Abstract

Two sensitive and accurate colorimetric and spectrofluonmetric methods, are presented for the determination of melatonin in tablets and serum. The first method utilizes the reactions of p-dimethylaminobenzaldehyde in hydrochloric acid (van Urk reagent)-ferric chloride in sulphuric acid (Salkowski reagent) mixture. The blue color of the resulting reaction product is measured at 630 nm. The second method is based on the reaction of melatonin with o-phthalaldehyde in acid medium which yields highly fluorescent condensation product that is measured at 465 nm as emission wavelength, using excitation wavelength at 355 nm. No interference was observed from tableting additives, and the applicability of the methods was examined by analysing tablets containing melatonin (single and combined with pyridoxine). Mean percentage recoveries from tablets were found to be 99.9+0.31 for single and 100.5+0.15 for combined tablets using colorimetric method, while by applying spectrofluorimetric method the recoveries were found to be 100.610.41 for single and 100.2+0.39 for combined tablets. Furthermore, the proposed methods were extended to the in-vitro determination of melatonin in serum. The detection limits are 0.27 ug ml^?1 for colorimetric method and 0.00035 ug ml^?1 for spectrofluorimetric method.     

Spectrophotometric Determination of Ternary Mixtures by the Derivative Ratio Spectrum-Zero Crossing Method

Abstract

A new spectrophotometric method is introduced for the assay of ternary mixtures with overlapping spectra. The method is based on the use of the first derivative of the ratio spectra and measurements of zero-crossing wavelengths. The ratio spectra were obtained by dividing the absorption spectrum of the mixture by that of one of the components. The concentration of the other components are then determined from their respective calibration graphs treated similarly. The method has been applied for the resolution of two ternary mixtures, namely, dipyridamole, aspirin and salicylic acid (I) and dipyridamole, oxazepam and 2-amino-5-chlorobenzophenone (II). Salicylic acid and benzo-phenone derivative are the degradation products of aspirin and oxazepam, respectively. The proposed method was applied for the assay of these combinations in synthetic mixtures and in commercial dosage forms. The results obtained were precise and accurate.     

Mikrotitrationen mit Äthylendiamintetraessigsäure. XIII

Zusammenfassung Es wird über die komplexometrische Bestimmung des Aluminiums berichtet und die Theorie der Titration behandelt. Man mißt einen Komplexonüberschuß mit eingestellter Zinkmaßlösung zurück, wobei ein Redoxsystem aus Ferri-ferrocyanid und 3,3-Dimethylnaphthidin als Indikator verwendet wird. Die Titration wird beiph 5 durchgeführt, wo erhebliche Mengen an Calcium und Magnesium keine Störung verursachen. Auch die Summe von Eisen + Aluminium kann auf diesem Wege bestimmt werden. Die Genauigkeit der Bestimmung beträgt ± 0,02 bis 0,03 ml 0,01-m Maßlösung.

---

Summary A report is given concerning the complexometric determination of aluminum and the theory of the titration is discussed. An excess of complexone is measured by means of standard zinc solution, using as indicator a redox system consisting of ferri-ferrocyanide and 3,3-dimethylnaphthidine. The titration is conducted atph=5, where even considerable amounts of calcium and magnesium do not interfere. The sum of iron + aluminum can also be determined in this way. The accuracy of the determination is±0.02 to 0.03 ml of 0.01 M standard solution.

---

Résumé On fait un rapport sur le titrage complexométrique de l'aluminium et l'on traite de la théorie du titrage. On dose en retour un excès de complexone avec une liqueur titrée de zinc en se servant du système rédox ferri-ferrocyanure et de la diméthyl-3,3 naphtidine comme indicateur. Le dosage s'effectue àph 5 auquel des quantités importantes de calcium et de magnésium ne troublent pas. La somme fer + aluminium peut aussi se déterminer de cette manière. La précision du dosage s'élève à±0,02–0,03 ml pour une solution 0,01 M.

     

Spectrofluorimetric Determination of Fluvoxamine in Dosage Forms and Plasma Via Derivatization with 4-Chloro-7-Nitrobenzo-2-Oxa-1,3-Diazole

A highly sensitive and simple spectrofluorimetric method has been developed and validated for the determination of the antidepressant fluvoxamine (FXM) in its dosage forms and plasma. The method was based on nucleophilic substitution reaction of FXM with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in an alkaline medium (pH 8) to form a highly fluorescent derivative that was measured at 535 nm after excitation at 470 nm. The factors affecting the reaction was carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was presented. Under the optimized conditions, linear relationship with good correlation coefficient (0.9995) was found between the fluorescence intensity and FXM concentration in the range of 65–800 ng ml⁻¹. The limits of detection and quantitation for the method were 21 and 64 ng ml⁻¹, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2.17%. The proposed method was successfully applied to the determination of FXM in its pharmaceutical tablets with good accuracy; the recovery values were 97.8–101.4 ± 1.08–2.75%. The results obtained by the proposed method were comparable with those obtained by the official method. The high sensitivity of the method allowed its successful application to the analysis of FXM in spiked human plasma. The proposed method is superior to the previously reported spectrofluorimetric method for determination of FXM in terms of its simplicity. The proposed method is practical and valuable for its routine application in quality control and clinical laboratories for analysis of FXM.     

Polarographic behaviour and determination of acrivastine in capsules and human urine

Dibenzo-18-crown-6 (DB18C6) is used for the liquid-liquid extraction, and recovery of titanium from paints, pigment, paper and pulp industries. The extraction mechanism of titanium(IV) from pH 4 medium with DB18C6 in dichloromethane was investigated. The DB18C6 concentration in organic phase, the concentration of titanium, the effect of pH and interference ions such as Mo(6+), V(5+), Nb(5+), Ta(5+), Zr(4+), Fe(3+), etc. in the aqueous phase and the temperature on the distribution coefficient for the Ti(IV) have been examined. The titanium was determined by spectrophotometric and inductively coupled plasma atomic emission spectroscopic (ICP-AES) method. Titanium forms a colourless complex with DB18C6 at pH 4.0 which is extracted with dichloromethane having molar absorptivity 1.53x10(4) lmol(-1)cm(-1) at 285 nm. It obeys Beer's law in the range of 0.16-3.84 ppm of titanium. The colour was developed with thiocyanate which has molar absorptivity 1.50x10(3) lmol(-1)cm(-1) at 425 nm. The extract is directly inserted in the plasma for ICP-AES measurement, which enhance the sensitivity several folds and the limits for estimation are 0.5-30 ngml(-1). The overall formation (logbeta(2)K'e) and extraction (K(ex)) constants calculated are 18.61+/-0.02 and 1.03+/-0.03x10(-10), respectively. The transportation of titanium has been discussed. The titanium is preconcentrated and determined in standard and environmental samples.     

Spectrophotometric and Spectrofluorimetric Methods for the Determination of Terazosin in Dosage Forms

Five simple and accurate methods are presented for the determination of terazosin (TZ) in tablets. These methods are based on: the direct measurements of the first and second derivative spectra of samples (A), the reaction of TZ with chloranil (CH) in aqueous solution of pH 9 to give an intense yellow color measured at 340 nm (B), the reaction of the drug with mercurochrome (MER) in aqueous alkaline medium to give an intense red color measured at 543 nm (C), the formation of an ion-pair salt between the drug and bromocresol purple (BCP) with subsequent absorbance measurements at 412 nm (D), and a sensitive fluorimetric method (E). The latter method was extended to determine TZ in presence of its degradation products.     

Spectrophotometric and Fluorimetric Methods for the Determination of Methoxamine Hc1 in Bulk Drugs and in Ampoules

Abstract

Three simple and sensitive methods for the determination of methoxamine HCl in bulk drugs and in ampoules were proposed. The methods are based on the oxidation of methoxamine HCl by sodium periodate, potassium permanganate and cerium(IV)sulphate. The first two reactions are followed spectrophotometrically by measuring the absorbance at 352 &; 608 nm for the periodate and permanganate methods, respectively. The third method is based on measuring the relative fluorescence intensity of Ce(III)arising from Ce(IV) at 348 nm with excitation wavelength at 257 nm. The different experimental parameters were carefully studied. Under the described conditions the proposed methods were applicable over the concentration ranges 10.0 - 40.0, 2.0-10.0 and 0.05-0.30 μg ml^?1 for the three methods, respectively.