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Antimicrobials, particularly antibiotics, are among the most common classes of drugs reported as substandard and falsified (SF) in developing countries. Therefore, it is important to develop simple and affordable analytical methods for the quality control of antimicrobial medicines. In this study, a liquid chromatographic method with ultraviolet detection (LC-UV) was developed and validated for the screening and quantification of 13 antimicrobial medicines and one beta-lactamase inhibitor in pharmaceutical formulations. LC separation was carried out on a Kinetex C18 column (150 mm × 4.6 mm, 2.6 µm) with gradient elution. The mobile phase consisted of mixtures of acetonitrile-water-10 mM phosphate buffer pH 3.5 at ratios of 3:92:5, v/v/v for mobile phase A and 50:45:5, v/v/v for mobile phase B with a flow rate of 0.5 mL/min. The screening method was intended for confirmation of the identity of the actives and validated for specificity and robustness, whereas the quantification method (using only a different detection wavelength) was further validated in terms of linearity, accuracy, sensitivity and precision (repeatability, intermediate precision). For all compounds, the method was found to be linear (r2 > 0.999), precise (%RSD < 1%), accurate (% recovery of 98–102%), sensitive, specific and robust. The developed LC method was successfully applied for the identification and assay of 12 antimicrobial samples from Ethiopia. Among the 12 samples analyzed, one (8.3%) product was confirmed to be falsified. [Display omitted] • Novel LC-UV method for screening and quantification of antimicrobial medicines. • Antimicrobial drugs mostly prone to counterfeiting were included in this study. • Successfully validated according to the ICH guidelines. • Method was applied to analyse suspicious samples. [ABSTRACT FROM AUTHOR]

• Determination of aloins and related anthrones in aloe leaf latex by new LC method. • Monolithic column allows use of conventional LC equipment and fast analysis (7 min). • Simple sample pretreatment. • Aloins A and B are baseline separated. • Aloins, aloinoside and microdontin were characterized by MS. Aloe leaf latex is a commonly used plant preparation in traditional medicine. However, quality control on the content of medicinally important constituents is often limited. Hence, establishing a reliable quality control method to identify and quantify bioactive markers is important to ensure safety and efficacy. In the present study, a novel liquid chromatographic (LC) method was developed and validated for efficient analysis of bioactive markers to evaluate the quality of aloe leaf latex. Quantification of marker compounds was possible in only 7 min on a monolithic column using gradient elution with 0.1 % formic acid in acetonitrile and water as mobile phases. The major compounds (aloins A and B) could be baseline separated together with related compounds within 10 min. The method showed excellent linearity with determination coefficients (r 2) of 0.9999. Detection limits were 0.017 and 0.013 μg/mL, while quantification limits were 0.057 and 0.043 μg/mL for aloin A and aloin B, respectively. Relative standard deviation (RSD) values for intra- and inter-day precision were less than 2% and recoveries for both aloins were close to 100 %. The robustness was evaluated using an experimental design. The method was applied to some aloe leaf latex samples from Ethiopia. Aloin contents varied from 14 to 35 % and two unknown peaks were tentatively identified as aloinoside and microdontin. [ABSTRACT FROM AUTHOR]