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–8 ] or mass spectrometry [ 9 , 10 ], or a combination of HPLC with mass spectrometry [ 5 , 11–13 ] or with electrochemical methods [ 14–16 ]. However, number of articles dealing with the determination of ampicillin is limited. Ampicillin is one of
carbapenems. The penicillin derivatives include, among others, amoxicillin (AMOX), ampicillin (AMP) and cloxacillin (CLOX). They are extensively prescribed for the treatment of potentially life-threatening infections including peritonitis, respiratory tract
Summary
A simple and fast high-performance thin-layer chromatographic method has been developed for the simultaneous determination of ampicillin and amoxicillin. Titanium(IV) silicate (a synthetic inorganic ion-exchanger)-coated thin-layer chromatography (TLC) plates were used to separate them, employing a mixture of K2HPO4 (0.1 M) + KH2PO4 (0.1 M), 1:1 (υ/υ), as mobile phase. The development time was 18 min. The plates were sprayed with fresh 1% solution of ninhydrin in ethanol. The developed method enables highly contrasted chromatograms with red purple spots in white background. Densitometric measurements were made at wavelength 546 nm using Camag TLC Scanner-3. The ampicillin and amoxicillin recovery of the total procedure were equal to 99.99 and 100.43, respectively. The procedure is quantitatively characterized. Linearities were r 2 > 0.9958 and 0.9954 for ampicillin and amoxicillin, respectively, and the relative standard deviations were <0.89 and 0.61, respectively. The limits of detection were 2.9 and 1.5 ng per spot and the limits of quantification were 14.5 and 7.5 ng per spot, respectively. The method is rapid, selective, precise, and accurate and thus can be used for the routine analysis of pharmaceutical preparations in quality control laboratories of the pharmaceutical industry. The method is successfully applied for the determination of ampicillin and amoxicillin in human blood plasma and urine.
Abstract
Ampicillin-cobalt complex has been investigated spectrophotometrically. The effects of pH and molar ratio of ampicillin to cobalt were studied. The stability constants for the complex formed at different pH values were determined. Gamma-radiolysis of ampicillincobalt complex in aqueous solutions was studied at doses from 20 to 100 Gy, using a137Cs source. The variations in UV and IR spectra due to their radiolysis were shown. The results showed an increase in absorbance values with increasing dose and this dependence is linear in the dose range studied. The mechanism of radiation effect on the complex is discussed.
Abstract
The complexation of β-lactam antibiotics, amoxicillin (AMPC), ampicillin (ABPC) and benzylpenicillin (PCG), with 2-hydroxypropyl-β-cyclodextrin (HPCD) was studied at various pH values using microcalorimetry, 1H NMR spectroscopy, and molecular dynamic simulation. In the strong acid solution, two different types of inclusion complex with a 1:1 stoichiometry, Complex I with a phenyl ring of β-lactam antibiotics penetrated into the cavity of HPCD and Complex II with a penam included in the cavity, were formed by hydrophobic interaction, and Complex II was more stable than Complex I. In aqueous solution at pH≥4.5, only Complex I was formed, where the penam of PCG was more deeply penetrated into the cavity to keep it stable than those of AMPC and ABPC. The charged carboxyl-group on the penam was less affinity to form Complex II.
Abstract
The formation of inclusion complexes between amoxicillin (AMPC) and 2-hydroxypropyl-β-cyclodextrin (HPCD) was investigated by isothermal microcalorimetry and molecular dynamics simulation to evaluate the inhibitory effects on the degradation of AMPC in aqueous solutions at various pH. The process depended significantly on the ionic species of AMPC in the solution. In a strong acid solution, cationic AMPC and HPCD formed two different types of inclusion complexes with a 1:1 stoichiometry: the first-type had a high association constant K 1 of 4.0-8.0103 M-1 and included the penam ring of AMPC in the HPCD cavity (Mode I), while the second-type with a K 2 of 1.0103 M-1 contained the phenyl group of AMPC (Mode II). Furthermore, a complex with a 1:2 (AMPC:HPCD) stoichiometry was realized in a two-step reaction and was characterized by a smaller K 1:2of 4.0102 M-1 and larger negative enthalpy and entropy changes than the complexes with a 1:1 stoichiometry. Since the β-lactam ring of AMPC could be protected by inclusion with HPCD in the 1:2 complex and Mode I of 1:1 complexes, the degradation of AMPC in the presence of HPCD was approximately four times slower than in its absence at pH 1.2 and 37C. In weak acid and neutral solutions, zwitterionic AMPC and HPCD formed only one type of inclusion complex with a 1:1 stoichiometry, where the phenyl group was included (Mode II). AMPC was very stable in these solutions (t 1/2=226 h at pH=6.0) and there is little significant difference in the degradation rate between complexed AMPC and uncomplexed AMPC. Thus, the results indicated that the inclusion complex of AMPC with HPCD, effectively increasing the stability of AMPC in a strong acidic solution like that the stomach, would be useful for eradicating Helicobacter pylori infection and as a drug delivery system.
Abstract
This paper reports results of the study on the influence of β-irradiation on the physical and chemical properties of selected salts of β-lactam antibiotics in solid state (sodium salt: ampicillin, azlocillin, benzylpenicillin, carbenicillin and piperacillin; potassium salt of benzylpenicillin, ampicillin anhydricum, ampicillin trihydricum, amoxicillin trihydricum and bacampicillin hydrochloride). The source of irradiation was a linear accelerator of electrons, and the irradiation effects were checked on the basis of the following: determination of mass, melting point and water contrent, and spectrophotometric (UV, IR) chromatographic and thermal (DTG, DSC) studies.
Penicillins and cephalosporins (subclasses of β-lactam antibiotics) are widely used against Gram-positive and Gram-negative bacteria. Use of HPLC, TLC-bioautography, and thin silica gel layers precoated with fluorescent material has been reported in literature for the analysis of these compounds. This manuscript deals with a straightforward and sensitive method for rapid separation and detection of selected β-lactams. Bulk impregnation of homemade silica gel G layers and impregnation of ready made silica gel 60 layers with 0.2% ammonium chloride was carried out and various mobile phases have been established for UV detection of the compounds. Separation of penicillins (benzylpenicillin, ampicillin, and amoxicillin) and cephalosporins (cephalexin, cefoperazone, ceftriaxone, cefixime, and cefadroxil) was achieved by use of propanol-acetic acid 4:1 ( v/v ) and butanol-acetic acid-water 4:1:2 ( v/v ) respectively, as mobile phases.
Excessive use of antibiotics leads to their occurrence into the environment. In spite of their benefit properties and desired effects during the therapeutic applications, the same properties can be disadvantageous for the environment having negative influences over the plants and microorganisms and the potential risks for human health. Regarding the monitoring of antibiotics and their subsequent elimination from environment, it is necessary to develop analytical procedures for their determination. In the present study, the quantitative determination of seven antibiotics belonging to three different classes is reported: tetracyclines (tetracycline and doxycycline), cephalosporins (ceftazidime and ceftriaxone), and penicillins (amoxicillin, ampicillin, and penicillin G) from surface waters. The proposed procedure consists of the solid phase extraction (SPE) of studied antibiotics from river water samples, their separation by high-perfomance thin-layer chromatography (HPTLC), and quantification by UV densitometry. The antibiotics were extracted from water matrices using hydrophilic-lipophilic-balanced Oasis HLB cartridges. The cartridge efficiency of the SPE method was checked by recovery experiments and evaluated by HPTLC. The chromatographic separation was performed on pre-coated Alugram SIL G/UV254 plates with ethyl acetate-methanol-acetone-water 5:2.5: 2.5:1.5 (v/v) mobile phase. The bands were detected and quantified at 254 nm by densitometry. For method validation, studies of selectivity, linearity, limits of detection and quantification, and precision and accuracy were achieved. The proposed procedure was applied to the determination of studied antibiotics on surface water samples collected from Someoul Mic River (Romania).
