Degradation of amoxicillin in aqueous solution using sulphate radicals under ultrasound irradiation

Degradation of the antibiotics amoxicillin in aqueous solution using sulphate radicals under ultrasound irradiation was investigated. The preliminary studies of optimal degradation methodology were conducted with only oxone (2KHSO₅·KHSO₄·K₂SO₄), cobalt activated oxone (oxone/Co²⁺), oxone + ultrasonication (oxone/US) and cobalt activated oxone + ultrasonication (oxone/Co²⁺/US). The chemical oxygen demand (COD) removal efficiency were in the order of oxone < oxone/Co²⁺ < oxone/US < oxone/Co²⁺/US for the amoxicillin solution. The variables considered for the effect of degradation were the temperature, the power of ultrasound, the concentration of oxone, as well as catalyst and the initial amoxicillin concentration. More than 98% of COD removal was achieved within 60 min under optimum operational conditions. Comparative analysis revealed that the sulfate radicals had the high oxidation potential and the use of ultrasound irradiation reduced the energy barrier of the reaction and increased the COD removal efficiency of organic pollutants. The degradation of amoxicillin follows the first-order kinetics.     

Electrospray ionization tandem mass spectrometric studies to probe the interaction of Cu(II) with amoxicillin简

This study describes the application of electrospray ionization mass spectrometry(ESI-MS) to investigate copper ion interaction with amoxicillin. ESI mass spectra of Cu–amoxicillin complexes show complex ions at m/z 828, 792, 753, 731, 428, 388 and 366 corresponding to [63Cu+(2A-H)+2H2 O]+, [63Cu+(2A-H)]+, [2A+Na]+, [2A+H]+, [63Cu+(A-H)]+, [A+Na]+and [A+H]+(where A = amoxicillin). Based on the observed m/z values of Cu–amoxicillin complex ions, it is found that the Cu–amoxicillin ratios are 1:1 and 1:2, and the copper ions exhibited three feasible coordination numbers(2, 4 and 6) with amoxicillin complexes. The structures and coordination numbers of copper–amoxicillin complex ions were probed from their collisionally activated dissociation(CAD) spectra. Based on these results, it is confirmed that the copper ions could form stable tetrahedral and octahedral complexes with amoxicillin. This study validates the applicability of ESI-MS for probing copper–amoxicillin complex ions.     

Fabrication of Micron Level Particles of Amoxicillin by Rapid Expansion of Supercritical Solution

In this study, the rapid expansion of supercritical solution (RESS) process was used to precipitate fine solid particles of amoxiccilin where supercritical carbon dioxide was used as a solvent. The process has been done by changing the RESS parameters, including extraction pressure (150–210 bar), extraction temperature (313–333 K), nozzle length (2–15 mm), effective nozzle diameter (450–1700 µm), and spraying distance (1–10 cm), to investigate the effect of these parameters on the size and morphology of the precipitated amoxicillin particles. The characterization (size and morphology) of the particles was examined using scanning electron microscopy (SEM). Based on the different experimental conditions, the mean particle size of the fabricated particles were between 1.08 and 5.72 µm, while the intact particles of amoxicillin were about 41.46 µm. Also, no regular changes in the morphology of the processed particles were observed.     

Comparison of Single Layer and Bilayer Biosensors Based on Crosslinking of Penicillinase for Potentiometric Detection of Penicillin in Milk and Antibiotics

The use of bilayers for fabrication of biosensors is advantageous for increasing enzyme loading. Substantial improvement in sensitivity is often achieved through immobilisation of the enzyme in both layers. In particular, the use of cross linking agents such as glutaraldehyde (GLA), bovine serum albumin (BSA) and polyvinyl alcohol (PVA) are beneficial for enhancing enzyme stability and, hence, for fabricating stable biosensors. The successful fabrication of a single layer BSA‐GLA‐P’nase biosensor for potentiometric detection of penicillin is described. Subsequently, the three crosslinking agents were employed with two polymers, polypyrrole (PPy) and polytyramine (PTy), together with penicillinase (P’nase) for fabrication of PPy‐NO₃‐P’nase/BSA‐PVA‐P’nase and PTy‐NO₃‐P’nase/BSA‐GLA‐P’nase bilayer biosensors. The analytical performances of the bilayer biosensors were then compared with the single layer BSA‐GLA‐P’nase biosensor for the determination of penicillin in milk and amoxycillin tablets. While the determination of penicillin in milk was somewhat problematic, its determination in amoxicillin tablets proved to be successful, with recoveries of 102±15 % obtained with the PPy‐NO₃‐P’nase/BSA‐PVA‐P’nase biosensor, 100±19 % with PTy‐NO₃‐P’nase/BSA‐GLA‐P’nase biosensor and 103±5 % with BSA‐GLA‐P’nase biosensor. Notably, the results of the latter agreed favourably with those obtained through a reference titrimetric method.     

Analysis of amoxicillin in human urine by photo-activated generation of fluorescence excitation-emission matrices and artificial neural networks combined with residual bilinearization

Fluorescence excitation-emission data recorded for amoxicillin after photo-activated reaction with periodate have been processed by a novel second-order multivariate method based on the combination of artificial neural networks and residual bilinearization (ANN/RBL), since the signals bear a strong non-linear relation with the analyte concentration. The selected chemometric methodology is employed for the first time to evaluate experimental non-linear second-order spectral information. Due to severe overlapping between the emission profiles for the analyte reaction product and for the urine background, calibration was done using different spiked urine samples. This allowed for the determination of amoxicillin in test spiked urines, other than those employed for calibration. When new urine samples containing a fluorescent anti-inflammatory were analyzed, accurate prediction in the presence of unexpected components required the achievement of the second-order advantage, which is provided by the post-training RBL procedure. Amoxicillin was also determined by ANN/RBL in a series of real urine samples, which allowed one to perform a comparison study with the reference high-performance liquid chromatographic technique.     

Identification of dimer impurities in ampicillin and amoxicillin by capillary LC and tandem mass spectrometry

A micro-scale liquid chromatography electrospray ionization tandem mass spectrometric method was developed for the identification of polymerized impurities in ampicillin and amoxicillin in aqueous solution. Ampicillin and amoxicillin are broad-spectrum antibiotics and widely used for the treatment of human and animal infections. In this study ampicillin, amoxicillin, and their dimers were trapped in a 5-cm capillary column containing C18 sorbents. The analytes were separated on a reversed-phase column and introduced into the mass spectrometer via a nanospray ion source. An isocratic mobile phase consisting of 1% formic acid-acetonitrile (50:50, v/v) was used. For identification, the fragment ions of the analytes were monitored. The aim of the present study was to develop an optimized quality control method for the analysis of high molecular weight impurities of ampicillin and amoxicillin.     

Simultaneous determination of β-lactamic antibiotics by a new high-performance low-pressure chromatographic system using a multisyringe burette coupled to a monolithic column (MSC)

A technique based on multisyringe chromatography (MSC) was developed to determine three beta-lactamic antibiotics. Amoxicillin (AMOXI), ampicillin (AMPI) and cephalexin (CEPHA) were analyzed using a system with a very simple design and very low-cost equipment consisting of a multisyringe module, three low-pressure solenoid valves, a monolithic Chromolith Flash RP-18e column and a diode array spectrophotometric detector monitoring at 250 nm. Mobile phases containing methanol:acetic acid (0.1 M)-sodium acetate (0.1 M), pH 6.2, were tested for various ratios of methanol:acetic acid-sodium acetate, but a ratio of 10:90 gave optimum results with a flow rate of 2 ml min(-1). Validation parameters were evaluated for amoxicillin. The response to amoxicillin was linear over the range 0.04-0.4 mg/mL, with a correlation coefficient of 0.9996; precisions, evaluated as the repeatability for 0.04, 0.16 and 0.4 mg/mL amoxicillin, were 0.6%, 0.1% and 0.6%, respectively. Recovery from a generic formulation of amoxicillin was evaluated. The method showed selectivity in the presence of excipients commonly used in capsules, and satisfactory specificity was observed for amoxicillin and hydrolytic degradation products. The linearity was also evaluated for cephalexin and ampicillin. The conditions selected for MSC separation were compared with those for a HPLC system, and similar results were obtained in terms of chromatographic parameters but a difference in retention times was observed.     

A kinetic study of synthesis of amoxicillin using penicillin G acylase immobilized on agarose

We presenta kinetic model for the synthesis of amoxicillin from p-hydroxyphenylglycine methyl ester and 6-aminopenicillanic acid, catalyzed by penicillin G acylase immobilized on agarose, at 25°C. Michaelis-Menten kinetic parameters (with and without inhibition) were obtained from initial velocity data (pH 7.5 and 6.5). Amoxicillin synthesis reactions were used to validate the kinetic model after checking mass transport effects. A reasonable representation of this system was achieved under some operational conditions, but the model failed under others. Nevertheless, it will be useful whenever a simplified model is required, e.g., in model-based control algorithms for the enzymatic reactor.     

毛细管电泳-电化学发光法研究阿莫西林在人尿中的药代动力学

建立了毛细管电泳一电化学发光(CE-ECL)法测定人尿中阿莫西林的新方法,并将该方法用于人尿中阿莫西林药代动力学的研究.结果表明:阿莫西林在尿液中平均回收率为95.35%,该方法的线性范围为0.001～5.0μg/mL,检出限(3σ)为0.32ng/mL,对1.0μg/mL阿莫西林连续测定6次,其相对标准偏差小于2.0%.给药后6 h内的排泄率为44.54%,人尿中阿莫西林最大药物浓度出现时间为1.0～1.5 h.本方法用于人尿中阿莫西林药代动力学的研究具有快速、简便、灵敏、样品用量少等特点.     

HPLC测定阿莫西林胶囊中的有效成分

建立了HPLC测定市售阿莫西林胶囊中有效成分的方法.采用Agilent C18柱（250mm×4.6mm,5μm）,以十八烷基键合硅胶为固定相,0.05mol·L^-1磷酸二氢钾溶液（用2mol·L^-1氢氧化钾溶液调节pH值至5.0）（A）-乙氰（B）（97.5∶2.5,V/V）为流动相.流速为1.0mL·min^-1,柱温为25℃,检测波长为254nm,进样量为10μL.实验结果表明：回归方程为y=5.27x＋2.83,r=0.9995（n=6）,线性范围20-500μg ·mL^-1,RSD为3.97％,样品中阿莫西林含量为821.3mg/g.此方法具有简单方便、灵敏度高、快速、准确性和重现性好等特点,可用于阿莫西林原料药及其制剂有效成分的质量控制.