Search

Membrane protected extraction is an ongoing innovation for isolation and pre-concentration of analytes from complex samples. The extraction process, clean-up and pre-concentration of analytes occur in a single step. The inclusion of solid sorbents such as molecularly imprinted polymers (MIPs) after membrane extraction ensures that selective double extraction occurs in a single step. The first step involves selective extraction using the membrane and diffused analytes are trapped on the solid sorbent enclosed in the membrane. No further clean-up is required even for very dirty samples like plant extracts and wastewaters samples. Sample clean-up occurs during extraction in the first process and not as additional step since matrix components are prevented from trapping on the sorbent. This can be referred to as prevention is better than cure approach. In this work, the analytical methods that employed membrane protected extraction for various organics such as pesticides, polycyclic aromatic hydrocarbons, and pharmaceuticals are reviewed. The designs of these analytical methods, their applications, advantages and drawbacks are discussed in this review. Literature suggests that the introduction of solid sorbents in membrane creates the much-needed synergy in selectivity. Previous reviews focused on membrane combinations with MIPs while discussing micro-solid-phase extraction. The scope of this review was broadened to include other sample preparation aspects such as membrane protected stir bar solvent extraction and membrane protected solid-phase microextraction. In addition, novel sample preparation methods for solid samples which include Soxhlet membrane protected molecular imprinted solid phase extraction and membrane protected ultra sound assisted extracted are discussed. [ABSTRACT FROM AUTHOR]

Regular monitoring of the chemical status of water bodies remains crucial in countries where data on chemical fingerprints that can assist in environmental policy is still limited. The current study focused on the concentrations of 14 metals and their sources in two important South African rivers that pass through various rural areas and two semi-urban towns in the province of the Eastern Cape. Most of the essential metals were within the South African guidelines for domestic water use except for selenium and iron which reached the concentrations of 131 and 712 µg L−1 that exceed the guideline values of 20 and 200 µg L−1, respectively. Cadmium and lead were above the South African Water Quality Guidelines and World Health Organization limits of 3 and 10 µg L−1, attaining the highest concentrations of 35 and 34 µg L−1, respectively. The impact of the wastewater treatment plant effluent and the municipal dumpsite leachates on metal ion concentrations in the rivers was observed for some metals. The metals source was related to deterioration of galvanized corrugated steel sheets from scrap yards and dwellings made-out of galvanized corrugated sheets, as well as agricultural activities and natural geological processes. An overview of the current water quality status of the two rivers may serve as a basis for sink-oriented pollutant fingerprinting toward sustainable water sources for communities. [ABSTRACT FROM AUTHOR]

Diospyros batokana (Ebenaceae) is used traditionally in Zambia to treat various ailments among degenerative diseases. This study aimed to screen the phytochemicals using chemical tests and LCMS/MS and evaluate the total phenolic and flavonoid contents and antioxidant activity of methanolic leaf extract of Diospyros batokana. Whereas maceration was used to extract phytocompounds for preliminary phytochemical screening, QuEChERS based method was used to extract polyphenolics in methanol for LCMS/MS screening. Total phenolic content was evaluated using the Folin-Ciocalteu method, at 765 nm. Total flavonoid content was estimated by aluminium chloride colorimetric assay at 510 nm. Antioxidant activity was determined using 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) free radical scavenging method, at 517 nm. Preliminary phytochemical screening revealed the presence of antioxidants; phenolic compounds and flavonoids, and various other important secondary metabolites such as alkaloids, terpenoids, and saponins. Total phenolic content was estimated at 50.3780 ± 0.1188 mg GAE/g, whereas total flavonoid content was estimated to be 105.5495 ± 0.4066 mg QE/g. LCMS/ MS polyphenolic screening revealed the presence of several phenolics and flavonoids such as gallic acid, quercetin, Kaempferol-3-O-glucoside, Quercetin 3'-O-glucoside, isoflavonoids, and flavones. The crude extracts displayed high DPPH free radical scavenging activity with a very low IC50 value of 13.08 µg/ mL. The high antioxidant capacity of the leaf extract of Diospyros batokana Ebenaceae might be the response for the use of the plant in traditional medicine in Zambia to manage and treat degenerative diseases. [ABSTRACT FROM AUTHOR]