Potassium permanganate–glyoxal chemiluminescence system for flow injection analysis of cephalosporin antibiotics: cefalexin, cefadroxil, and cefazolin sodium in pharmaceutical preparations Yuanyuan Sun, Yuhai Tang, Hong Yao, Xiaohui Zheng Department of Chemistry, College of Science, Xi’an Jiaotong University, Xi’an 710061, PR China Received 27 October 2003; received in revised form 2 February 2004; accepted 2 February 2004 Abstract
A sensitive flow injection chemiluminescence (FL-CL) method for the determination of cephalosporin antibiotics, was developed. The method was based on that cephalosporin antibiotics could enhance the CL reaction of glyoxal and KMnO4 in sulfuric acid. Method developmentincluded the optimization of reagent concentrations and flow-rate. Under the optimized conditions, three cephalosporin antibiotics: cefalexin,cefadroxil, and cefazolin sodium, were determined. The detection limits of the method are 10 ng ml−1 cefalexin, 2 ng ml−1 cefadroxil, and2 ng ml−1 cefazolin sodium. The method was successfully applied to the determination of three cephalosporin antibiotics in pharmaceuticalpreparations.
2004 Elsevier B.V. All rights reserved.
Keywords: Chemiluminescence; Flow injection; Cephalosporins; Pharmaceutical preparations 1. Introduction
cence reaction of cefadroxil with potassium permanganatein sulphuric acid, sensitized by quinine.
Cephalosporins, a kind of ␤-lactam antibiotics with a The present paper described a new flow injection CL basic structure of 7-aminocephalosporanic acid, are widely method for the determination of three cephalosporin an- used to treat respiratory tract infection, prostatitis, urinary tibiotics: cefalexin, cefadroxil, and cefazolin sodium. The tract infection, skin, and soft tissues infection that often re- method was based upon the enhancing effect of these an- sult from encroachment of sensitive bacteria. Many methods tibiotics on the CL reaction of glyoxal with potassium per- have been reported for the determination of cephalosporins, manganate in acid condition. Compared with the previous reported chemiluminescence methods for cephalosporins the present method shows lower detection limits only few reports on chemiluminescence (CL) methods for and wider calibration ranges. The method was applied to the the determination of cephalosporins. Kubo et al. determination of cefalexin, cefadroxil, and cefazolin sodium ported a flow injection analysis method for the detection in pharmaceutical formulations with satisfactory results.
of cephalothin. It was based on the direct chemilumines-cence reaction of ␤-lactam antibiotics with luminol in thepresence of hexacyanoferrate(III) and hexacyanoferrate(II) 2. Experimental
in alkaline solution. Aly et al. veloped a flow in-jection chemiluminescent (FL-CL) method for the determi- nation of cefadroxil monohydrate with a detection limit of50 ng ml−1. The method is based upon the chemilumines- Analytical reagent grade chemicals and double distilled water were used to prepare all solutions.
∗ Corresponding author. Tel.: +86-29-5275399; fax: +86-29-5275135.
Cefalexin, cefadroxil, and cefazolin sodium samples E-mail address: (Y. Tang).
were purchased from National Institute for the Control of 0039-9140/$ – see front matter 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.talanta.2004.02.012 Y. Sun et al. / Talanta 64 (2004) 156–159 KMnO4–cephalosporins solution. The calibration graphswere prepared by plotting the CL peak height against theconcentration of the cephalosporins.
2.3.2. Procedure for pharmaceutical preparations Cefalexin capsules (250 mg per capsule), cefadroxil tablets (250 mg per capsule) and cefazolin sodium for injec- Fig. 1. Schematic diagram of the flow system for determination of tion (500 mg per bottle), were purchased from local markets.
cephalosporins. (a): Glyoxal solution; (b): KMnO Each sample stock solution was prepared by dissolving a ple solution; (M): Manifold (P): Peristaltic pump; (V): Six-way injection quantity of the mixed content, equivalent to 250 mg of this valve; (F): Flow cell; (PMT): Photomultiplier tube; (HV): High voltage; cephalosporin, from 10 capsules, tablets or bottles with (COM): Computer; (W): Waste solution.
water. Before analysis, the stock solutions were diluted ap-propriately to ensure the concentration of each within the Pharmaceutical and Biological Products (Beijing, China).
KMnO4 was obtained from Xi’an Chemical Reagent Fac-tory (Xi’an, China). Glyoxal was provided by ChemistryDepartment of Xi’an Jiaotong University. Dosage forms 3. Results and discussion
containing cefalexin, cefadroxil, and cefazolin sodium werepurchased from local markets.
3.1. Effect of different acid concentrations The 1 × 10−3 mol l−1 KMnO4 working solution was pre- pared by diluting appropriate 0.1 mol l−1 stock solution in It was observed that the CL signal of KMnO water. The 0.05 mol l−1 working solution was prepared by system was stronger in acid solution than in neutral or ba- diluting appropriate 1 mol l−1 glyoxal solution in water.
sic solution. Four different acids (i.e. HCl, HNO The 1.0 mg ml−1 standard solutions of cefalexin, ce- fadroxil, and cefazolin sodium were daily prepared by 2SO4) of different concentrations, as the mediums for dissolving 0.2500 g of each in water and diluting with water 4, over the range of 0.1–2 mol l−1 were tested. The results showed maximum CL intensity was obtained with to 250 ml. The standard solutions were stored in the refrig- erator and protected from light. The testing solutions were 2SO4. The effect of H2SO4 on the CL reaction prepared by appropriate dilution of these standard solutionswith water before used.
3.2. Effect of KMnO4 concentration The effect of 1 × 10−4–1 × 10−2 mol l−1 KMnO4 on ws the schematic diagram of the flow injection the CL intensity was examined. The CL intensity contin- chemiluminescence system. One peristaltic pump was used ued to increase with increasing KMnO4 concentration up to 1.0×10−3 mol l−1. The experimental results showed that 1× other peristaltic pump was used to pump glyoxal solutions.
10−3 mol l−1 could give rise to the larger CL response and All components were connected with PTFE tubing (0.8 mm lower background signal. Larger concentration of KMnO4 i.d.) in the flow system. Reagent solutions were injected into could lower the CL intensity. Thus, 1×10−3 mol l−1 KMnO4 the flow system by a six-way injection valve. A photomul- tiplier tube was used to detect the CL. The CL signal wasrecorded with IBM-compatible computer, which was em-ployed an IFFL-D model flow-injection CL analysis systemsoftware (Xi’an Ruike Electronic Equipment Corporation,Xi’an, China).
A series of working solutions of three cephalosporin antibiotics with different concentrations were prepared bydiluting respective concentrated standard solutions. KMnO4solution in sulfuric acid was mixed with the cephalosporinssolution in a manifold prior to reaching the six-way injec- Fig. 2. Effect of H2SO4 concentration of KMnO4 on the CL inten- tion valve. Glyoxal solution was injected into the flow cell sity. Conditions: cefalexin, 0.1 ␮g ml−1; glyoxal, 0.05 mol l−1; KMnO4, by the six-way injection valve to combine with the mixed Y. Sun et al. / Talanta 64 (2004) 156–159 eters of the calibration curves and the calculated detectionlimits (S/N = 3).
In order to assess the selectivity of the proposed method, the effect of some common inorganic ions and organiccompounds was studied by preparing solutions containing0.1 ␮g ml−1 of cefalexin. It was considered not to interfereif a foreign material caused a relative error of less than±5% during the determination of 0.1 ␮g ml−1 cefalexin.
The results showed that no interference had been foundwhen including up to a 1000-fold Na+, K+, Mg2+, Ba2+, Fig. 3. Effect of glyoxal concentration on the CL intensity. Conditions: cefalexin, 0.1 ␮g ml−1; KMnO4, 1 × 10−3 mol l−1.
acid, 500-fold carbowax, 100-fold Zn2+, five-fold Al3+,and two-fold CO 2− 3.3. Effect of glyoxal concentration The effect of 0.02–0.15 mol l−1 glyoxal on the CL inten- Following the procedure detailed in the pro- sity was examined. The CL intensity continued to increase posed method was applied to the determination of cefalexin, with increasing glyoxal concentration up to 0.05 mol l−1.
cefadroxil and cefazolin in pharmaceutical formulations.
The experimental results (showed the CL intensity The results were listed in and agreed well with continued to increase with increasing glyoxal concentration up to 0.05 mol l−1. When the glyoxal concentration is be-yond 0.05 mol l−1, the intensity of the CL signal is trending stable. In this work, 0.05 mol l−1 glyoxal was selected.
It was reported that KMnO4 could react with some 3.4. Calibration curves, detection limits, and precisions reductants in the presence of formaldehyde to produce1O 1 g), a complex oxygen molecule of single The method allowed the determination of 0.01–1 ␮g ml−1 state, which could transform into 3O2 (3 g), a triplet state cefalexin, 0.01–1 ␮g ml−1 cefadroxil, and 0.1–5 ␮g ml−1 ce- oxygen. During the transformation, it could produce CL and fazolin sodium. The relative standard deviations for 11 repli- the formaldehyde could accelerate oxidation reaction rate cate measurements of cefalexin, cefadroxil, and cefazolin Thus it was assumed that the cephalosporins could sodium were 1.1, 1.3, and 1.5%, respectively, when their also react with KMnO4 to produce CL and the CL reaction concentrations were at 0.1 ␮g ml−1. the param- Table 1Calibration curves of the studied cephalosporins Regression equation Y = a + b a Y = a + b X where Y is the concentration in 0.1 ␮g ml−1 and X is the CL intensity.
Table 2Determination results of cephalosporins in samples Cefazolin sodium for injection (No.: B02082916) Y. Sun et al. / Talanta 64 (2004) 156–159 Based on the above discussions, the possible reaction References
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4. Conclusion
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This work was financially supported by Xi’an Jiaotong


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