Flow Injection Spectrophotometric Determination of Tetracycline in a Pharmaceutical Preparation by Complexation with Aluminium(III)

Abstract

Tetracycline is one of the broad-spectrum antibiotics 1,2 having a fused, partially aromatic, 4-ring structure with a wide variety of functional groups that form complexes with various metal ions in aqueous solution. This ability is responsible for its antibacteria action. 3,4 Numerous methods have been reported for determining tetracycline in many matrices, for example: microbiological, 5,6 electrochemical, [7][8][9][10][11] chromatographic, 12-17 capillary electrophoresis, 18,19 spectrophotometric, 20-23 fluorometric, 24,25 and chemiluminescence [26][27][28][29] procedures. The microbiological assay is sensitive, but requires a long period of incubation and lacks precision and specificity. Some spectrophotometric methods are rather insensitive and subject to interference from other materials. The fluorometric method is less sensitive than the microbiological method, but is specific for tetracycline. Other methods require elaborate instrumentation or have a low sampling frequency.Most spectrophotometric and fluorometric methods, 30-34 including chromatographic methods with spectrophotometric and fluorometric detections 35,36 for the determination of tetracyclines, are based on their abilities to bind with metals, such as iron(III), 30,31 copper(II), 32 magnesium(II) 33,34 and some lanthanide ions, especially those of europium, samarium and terbium. 34 Since the conventional spectrophotometric methods for tetracycline determinations are tedious and time consuming, flow injection analysis (FIA) methods with chemiluminescence [26][27][28][29] and spectrophotometric 32,37 detection have been employed instead. The FI method is suitable for rapid quality control in drug industries where these drugs are manufactured because of its high sample throughput, which enables a large number of samples to be determined with cost effectiveness. This paper describes a rapid, sensitive, and reproducible flow injection (FI) method for the quantitation of tetracycline based on the spectrophotometric detection of the colored product formed by the reaction between this drug and aluminum(III) in a Tris-buffer pH 7 medium. The resulting Al(III)-tetracycline complex is measured at 376 nm. Experimental Reagents and solutionAll chemicals were of analytical reagent grade and were used without further purification. Deionized distilled water was used throughout the whole experiment. A standard stock solution of tetracycline (100 mg l -1 ) was prepared by dissolving tetracycline (0.10 g obtained from Fluka Switzerland) in 1 L water. Futher dilutions with water were made for appropriate concentrations. A 0.0100 mol l -1 aluminum(III) chloride hexahydrate (BDH Chemical Poole, England) was prepared in 1 L of water. A rapid flow injection (FI) spectrophotometric procedure for tetracycline determination is described. It is based on the injection of a 100 µl sample solution containing tetracycline into merged streams of aluminium(III) chloride (0.01 mol l -1 ) and Tris-buffer in the presence of KCl (0.06 mol l -1 ), pH 7.0, with the same optimum f...

Using 9-Chloroacridine as A Chromogenic Reagent for The Detection of Tetracycline

“…This has been changed with tetracycline semisynthetic compounds such as doxycycline and minocycline [3]. Many approaches have been described for the detection of TCs, in bulk material and pharmaceutical formulation including spectrophotometry[5-9], voltammetry[10-13], HPLC methods[14, 15], LC-MS methods [16][17][18], chemiluminescence [19,20] and flow injection analysis methods [21][22][23][24]. Conversely; most of these approaches are either inadequately sensitive, time-consuming, tedious, suffered from interference compounds, used an organic solvent and required an extraction step [25] or limit linear range [26].…”

Determination of tetracycline hydrochloride in some pharmaceutical products using flow injection spectrophotometric technique

“…These compounds are particularly useful in several types of both common and rare infections including atypical pneumonias, rickettsial infections, chlamydial infections, Lyme disease and ehrlichiosis [1,5,6,7,8]. A number of spectrophotometric and flow injection analysis methods have already been used successfully for the determination of tetracycline hydrochloride [9,10,11,12,13,14]. Several liquid chromatographic methods have been described [15,16,17], a polarographic technique [18], chemiluminescence [19] and fluorimetric [20] have been used for determination tetracycline hydrochloride.…”

Flow-injection spectrophotometric determination of tetracycline and doxycycline in pharmaceutical formulations using chloramine-T as oxidizing agent

“…Since the conventional spectrophotometric methods for tetracyclines determinations are tedious and time consuming, flow injection analysis (FIA) methods with chemiluminescence, [24][25][26][27] amperometric [28][29][30] and spectrophotometric [31][32][33][34] detection have been employed instead. The automated flow injection analysis systems with spectrophotometric detection present as main disadvantages the relatively high cost of reagents, 32 very low sampling rate 34 and low selectivity.…”

“…The automated flow injection analysis systems with spectrophotometric detection present as main disadvantages the relatively high cost of reagents, 32 very low sampling rate 34 and low selectivity. 31,33 The methodologies that employ flow systems with amperometric [28][29][30] and chemiluminescence detection, [24][25][26][27] despite their high analytical sensitivity, present the disadvantages of relative high cost [28][29][30] as well as the use of oxidizing reagents which are expensive 25 or highly toxic. 26,27 Visible absorption spectrophotometry was applied in pioneering works on flow injection analysis.…”