Antibiotics are certainly miracle drugs and have comprehensive usages in humans and livestock for the treatment of various bacterial diseases. However, inappropriate or misuse of antibiotics can lead to the development of antimicrobial-resistant bacteria. Antibiotic resistance happens when bacteria change in responding to the usage of these medicines. These bacteria can also be disposed of from animals to humans via contact between humans and animals directly, or through the food chain and the environment. Antibiotic resistance is a great threat to global humanity as it can prolong treatment in hospitals, increase medical costs, increase mortality, and burden the family. Residual antibiotics above the maximum residue limit (MRL) are harmful to human health and animals and need to be monitored. By increasing national policies, international declarations, agreements for enough chemical and analytical instrumental facilities, and above all, creating awareness about the harmful effect of resistance, the situation of antibiotics resistance can be improved.

A total of forty-five pharmaceutical tablets containing 500 mg azithromycin from 9 (nine) different companies were collected from local pharmacies and evaluated the quality of the antibiotics with standard azithromycin by physical, chromatographic (HPLC), Fourier Transform Infrared (FT-IR), and 1H & 13C Nuclear Magnetic Resonance (NMR) spectroscopic studies. Weight variation of all tested tablets were within 0.1-1.8% which is in the allowed variation of 5%. Two prominent absorption bands were observed at 1723 and 1187 cm−1 in the FT-IR spectrum of all samples and standard for the presence of >C=O and -C-O groups, respectively due to the macrocyclic lactone ring. HPLC coupled with PDA detector (at 210 and 215 nm) gave reproducible results at retention time of 10.5 min for standard and samples. The 1H and 13C NMR spectral data of the standard azithromycin and test samples were found to be identical which led to the conclusion that 1H- and 13C-NMR experiments are feasible tools for qualitative determination of azithromycin in tablets. All the described methods determined the quality of analyzed tablets well. Bangladesh Pharmaceutical Journal 24(1): 37-44, 2021

The objective of the study was to quantify tetracycline (TCs) i.e., oxytetracycline (OTC), tetracycline (TC) and chlortetracycline (CTC) residues in thirty poultry meat samples (n = 30) collected from the local market and super shop around the Dhaka University campus during May 2019 to January 2020. Three samples were collected from each of ten locations. All samples were extracted by Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method. Samples were analyzed by reversed-phase High-Performance Liquid Chromatograph equipped with Photo Diode Array Detector (LC-PDA) and a reported method was validated with good linear correlation coefficients of standards and matrix-matched calibration curves with r2=1.00, 0.99, 0.99 and r2= 0.99, 0.99,0.99 in the linearity range of 0-10 µg/kg for OTC, TC and CTC, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for OTC, TC, and CTC were 1.05, 1.17, and 1.09 μg/kg and 3.15, 3.51 and 3.27 μg/kg, respectively. Accuracy that is expressed by the recovery percentages were calculated at two different concentrations (2.5 and 5 μg/kg) were 91 and 100%, 102 and 100%, and 106 and 100% for OTC, TC, and CTC, respectively. Intra-day (n=3) and inter-day (n=9, 3 days) precision data were under 10% for all sample matrixes. Standard deviations were calculated ±0.06, ±0.11 and ±0.03 and precision (expressed by RSD%) were found 5.57, 9.14 and 2.35%, respectively for OTC, TC and CTC. The HPLC-PDA method is affordable for screening of large number meat samples for residual antibiotics in biological matrices by any laboratories. The method is also cheaper in comparison with LC-MSMS. Analysis of real 30 poultry meat samples showed that the tetracyclines residues were below the quantification limit in all samples.

Bangladesh has a vast natural water resources. In order to determine the water quality parameters such as pH, EC, DO, BOD, TOC, ionsi.e., NO3-, SO42-, PO43- and heavy metals, thirty surface water samples were collected from the southern part of Bangladesh includingthe coastal regions of Patuakhali district and Kuakata sea beach area during the dry season. The pH of water samples was ranged from7.58 to 8.77 with an average of 8.15. The average conductivity value was 8.83±2 mS/cm. The average DO was 8.33±1.82 mg/L andBOD was 0.31±0.03 mg/L. TOC was found between 0.78 and 1.78 mg/L with an average of 1.24 mg/L. The concentration of NO3-,SO42-, PO43- was determined by ion chromatography and only sulphate ion was detected in a very low concentration. Water samplesfrom different sources were analysed for five metals by AAS and the concentrations of Pb, Cd, Mn, Hg and As were below 0.2, 0.01,0.22, 0.001 and 0.005 mg/L, respectively. Dhaka Univ. J. Sci. 70(1): 49-57, 2022 (January)