Abstract
M.Sc. (Nanoscience)
Climate change and other environmental factors play a role in the extensive growth of
cyanotoxins and aflatoxins in natural water and agricultural commodities respectively. This
poses serious concern due to their effect on food availability and safe drinking water supply
more especially in human health. Therefore, the aim of the study was to apply nano-adsorbent
(silica@multiwalled carbon nanotubes and activated carbon@iron oxide@manganese oxide)
for the extraction and preconcetration of these toxins. The subsequent paragraphs discuss the
summary of results obtained when each composite was applied for preconcentration of
toxins.
A simple, rapid and effective method based on dispersive solid phase microextraction
(DSPME) and UV-Vis spectrophotometer was developed for the preconcetration and
determination of microcystin-LR (MC-LR) in environmental matrices. An activated carbon@
iron oxide@manganese oxide composite was used as solid phase material. The composite
was characterized by scanning electron microscope/energy dispersive X-ray spectroscopy
(SEM/EDS), transmission electron microscope (TEM), X-ray powder diffraction (XRD),
nitrogen adsorption and FTIR. The factors affecting the DSPME were optimised using
multivariate strategy. Under optimised condition, the LOD, LOQ, repeatability (n=10),
reproducibility (n = 5) and preconcentration factor were 0.5 μg L−1, 1.7 μg L−1, 3.1, 4.5% and
50, respectively. The percentage recovery of MC-LR in spiked water samples was found to
be 98.5%. The developed method DSPME/UV method was simple, rapid, cost-effective and
can be used for the detection of MC-LR in real samples without any expensive or challenging
equipment.
The reliable, simple, rapid and cost-effective extraction method based on an
(Ultrasonic-Assisted dispersive solid phase microextraction) UA-DSPME method using
silica@multiwalled carbon nanotubes hybrid nanostructures combined with
spectrophotometric detection was applied for the first time for preconcentration and
determination of aflatoxin B1 (AFB1) in liquid milk samples. Two level factorial design and
central composite design in combination with response surface methodology was used to
evaluate the factors affecting extraction and preconcentration procedure. The influence of
different variables including mass of adsorbent, extraction time, eluent volume and sample
volume was investigated in the optimization study. Under the optimal conditions, a dynamic
linear range of 0.3–250 μg L−1 with limits of detection of 0.1 μg L−1 was obtained. The...