Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs have been continually studied due of their toxic consequences. Monitoring water quality to assess the presence of MCs is of utmost importance although it is often difficult because CyanoHABs may generate multiple MC variants, and their low concentration in water. To effectively manage and control these toxins and prevent their health risks, sensitive, fast, and reliable methods capable of detecting MCs are required. This paper aims to review the three main analytical methods used to detect MCs ranging from biological (mouse bioassay), biochemical (protein phosphatase inhibition assay and enzyme linked immunosorbent assay), and chemical (high performance liquid chromatography, liquid chromatography-mass spectrometry, high performance capillary electrophoresis, and gas chromatography), as well as the newly emerging biosensor methods. In addition, the current state of these methods regarding their novel development and usage, as well as merits and limitations are presented. Finally, this paper also provides recommendations and future research directions towards method application and improvement.

It is vital to understand the adsorption mechanisms and identify the adsorption kinetics when applying an adsorbent to remove heavy metals from aqueous solution. A Pb(II) imprinted magnetic biosorbent (Pb(II)-IMB) was developed for the removal of Pb²⁺ via lead ion imprinting technology and crosslinking reactions among chitosan (CTS), Serratia marcescens and Fe₃O₄. The effect of different parameters such as solution pH, adsorbent dosage, selectivity sorption and desorption were investigated on the absorption of lead ion by Pb(II)-IMB. The adsorbent was characterized by a Brunauer-Emmett Teller (BET) analysis, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The adsorption kinetics, equilibrium and thermodynamics of Pb(II)-IMB for Pb(II) were studied. The results of the abovementioned analyses showed that the adsorption kinetic process fit well with the second-order equation. The adsorption isotherm process of Pb(II) on the Pb(II)-IMB was closely related to the Langmuir model. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of Pb(II) by Pb(II)-IMB. The adsorption mechanism of Pb(II)-IMB was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the nitrogen in the amino group and the oxygen in the hydroxyl group of Pb(II)-IMB were coordination atoms.