Investigation of an amoxicillin oxidative degradation product formed under controlled environmental conditions

Abstract

Environmental context.Although amoxicillin is a widely used antibiotic, it is yet to be detected in the aquatic environment. This study traces the production of the amoxicillin-S-oxide degradation product, and shows that it is consistently obtained only under sunlight irradiation. This is the first study to demonstrate the formation, under controlled environmental conditions, of this chemically stable product of amoxicillin. Abstract.Amoxicillin (AMX) is a widely used penicillin-type antibiotic, and its presence in the environment has been widely investigated. The formation and structure of an oxidised degradation product (DP) of AMX are described in the present work. The experiments were carried out in buffer solution (pH 7.5) containing AMX at a concentration of 100 μg mL–1, with and without acid and in field secondary effluent. The DP, AMX-S-oxide (sulfoxide), was consistently obtained only under sunlight irradiation and was significantly augmented by the addition of humic acid (5 mg L–1) and mainly in field secondary effluent, which acts as a natural photo-sensitiser. The structure of the AMX-S-oxide DP was determined by an LC-MS technique using a mobile phase of deuterated and non-deuterated solvents. A 1H NMR spectrum was obtained for the pure compound isolated by preparative HPLC. Further confirmation of the AMX-S-oxide structure was achieved by comparison of its UV spectrum with those of the two oxidation products, AMX-S-oxide and hydroxylated AMX, obtained by the ozonolysis of AMX.

Amoxicillin in the Aquatic Environment, Its Fate and Environmental Risk

“…It is worth noting that the presence of this compound in aquatic environments is of great concern, because the AMX-S-oxide β-lactam ring is still active and may lead to the development of resistant bacteria and even cause other possible health hazards to human and wild and domestic animals [93].…”

“…To sum up, it is important to remark that these degradation products are suspected of being more resistant to degradation, and potentially more toxic, than the parent compound [36,66,70,93].…”

Mechanism of Ampicillin Degradation by Non-Thermal Plasma Treatment with FE-DBD

“…This was attributed to oxidation of the sulfur, as this modification places one of the CH 3 groups into a cis position with the oxygen and results in a trans-positioning with the other CH 3 group. The methyl group in the cis-position is in closer proximity to the oxygen, which causes deshielding and a shift downfield [53]. A visible shift in H-4, and even splitting of the H-2 and H-6 peaks were caused by this oxidation, as well [54].…”

Adsorption and photooxidation of pharmaceuticals and personal care products on clay minerals

“…[9][10][11]. Because many PPCPs are inherently biologically active and designed to resist biodegradation, drug residue degradation caused by microorganisms is not an essentially important elimination process in surface waters [11,12].…”