Wan Mohd Afiq Wan Mohd Khalik

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Verified

Wan verified their affiliation via an institutional email.

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• Doctor of Philosophy (Analytical Chemistry)
• Professor (Associate) at University of Malaysia, Terengganu

Efficient preconcentration techniques are crucial for the analysis of calcium channel blocker drugs such as amlodipine and nifedipine, commonly used for hypertension and heart diseases. This study optimized the pre-concentration conditions using CO 2 effervescence powder assisted deep eutectic solvent dispersive liquid-liquid microextraction (EP-DL...

This study demonstrated magnetic effervescent tablet-assisted (META) ionic liquid (IL) dispersive liquid–liquid microextraction (DLLME) as a procedure for extracting pharmaceutical drugs from water samples. An effervescent tablet (ETA) comprising precursors, citric acid and sodium bicarbonate; iron oxide nanoparticles; and IL, 1-butyl-3-methylimida...

Liquid phase microextraction is a state-of-the-art micro-analytical work with numerous advantages documented in the scientific literature. One of the most intriguing subclasses is the CO2-effervescence assisted dispersive liquid−liquid microextraction method. Working theory was based on an acid-based reaction involving a proton donor and a carbon d...

This study discovered the extraction procedure of acetaminophen from water samples using the effervescent tablet-assisted dispersive liquid-liquid microextraction (DLLME) method. The effervescent tablet that is composed of sodium dihydrogen phosphate (proton donor) and sodium carbonate (CO2 source) was formulated using the wet granulation technique...

Amlodipine and nifedipine, both widely used calcium channel blockers (CCBs) for hypertension treatment, have emerged as environmental contaminants in water sources such as lakes, rivers, and oceans due to inadequate effluent treatment. In this study, activated carbon derived from peanut shell waste was utilized in magnetic solid-phase extraction (m...

Sample preparation is important to produce a clean extract to enhance detection sensitivity and minimize instrument maintenance. A micro-solid phase extraction (µ-SPE) technique using magnetic molecularly imprinted polymers (magnetic-MIPs) as the adsorbents combined with micro-high performance liquid chromatography and ultraviolet detection (µ-HPLC...

Microplastics have emerged as a pressing environmental concern, exerting profound impacts on ecosystems, water bodies, terrestrial landscapes, and human food sources. In light of the global plastic waste crisis, innovative strategies are being explored to manage and recycle plastic waste, with an emphasis on microplastics. Research endeavours aimed...

Milk carries significant amounts of essential fats and nutrients such as magnesium, calcium and zinc. Hence, they have always been the significant components consumed by all age groups, especially infants and elderly seniors. However, the lipophilic nature of polycyclic aromatic hydrocarbons (PAHs) increases the likelihood of depositing fats within...

The extensive use and disposal of various petroleum‐derived plastics has become a major cause of environmental pollution. The urgent need for sustainable materials to address plastic waste have resulted in the production of biodegradable plastics. In this study, a biodegradable plastic film is produced by incorporating chitosan with starch from Mal...

The growing attention to microplastics stems from their significant environmental and human impacts. Microplastic accumulation in the environment also contributes to the spread of micropollutants. Daily human activities involving the use of plastics, especially synthetic materials, lead to their eventual presence in wastewater treatment plants (WWT...

The adsorptive performance of mechanochemically synthesized copper (II) isonicotinate metal–organic frameworks ([Cu (INA)2]-MOFs) on ractopamine in water is reported. The MOF characteristic was revealed by Fourier transform infrared (FTIR), showing all the projected functional groups. The X-ray diffraction (XRD) diffractogram shows an excellent cry...

Microplastics (MPs) constitute an emerging class of pollutants that have garnered significant attention due to their omnipresence in marine and freshwater ecosystems. Particles with a diameter of less than 5 mm result from the degradation of larger plastic debris and the production of commercial plastic products. The pervasive occurrence of MPs in...

This research article presents a study on the potential use of oil-based ferrofluid for the efficient removal of microplastics from water. The targeted analyte, micro-polystyrene (micro-PS), was chosen along with palm oil as the carrier liquid. Fourier Transform Infrared (FTIR) analysis was conducted to identify the main peaks in the ferrofluid, in...

Polycyclic aromatic hydrocarbons and endocrine-disrupting phenols are both ubiquitous pollutants in the environment. Human activities through urbanisation and rapid industrialisation are at the forefront of global environmental pollution. Therefore, removing pollutants in miscellaneous characteristics is important to eliminate the stage-by-stage re...

Clean water quality is dependent on the absence or complete removal of polar ionic micropollutant molecules and their associated products from the water. Utilizing copper Isonicotinate metal–organic frameworks ([Cu (INA)-MOF) a modified copper-based magnetic composite metal–organic framework ([Cu (INA)2]-MOF@Fe3O4) is mechanically synthesized under...

Fluoroquinolones are used to treat and prevent serious bacterial infections. They are widely applied in the husbandry and veterinary areas as well as in the human medication scope. There is an emerging concern about the residues of fluoroquinolones in the environment. Once in the environment, especially in the water bodies, they will be taken up an...

Microplastics (MPs) with the size of 1 μm-5 mm are pollutants of great concern ubiquitously found in the environment. Existing efforts have found that most of the MPs present in the seas mainly originated from land via riverine inputs. Asian rivers are known to be among the top in microplastic emissions. However, field data are scarce, especially i...

Mechanochemical production of copper (II) isonicotinate Metal-Organic Framework ([Cu (INA)2]-MOF) and its modified magnetic iron composite ([Cu (INA)2]-MOF@Fe3O4]) allowed for the adsorptive removal of Terbutaline from water. A variety of characterization techniques, including Fourier, transform infrared spectroscopy (FTIR), thermogravimetric analy...

Copper-based Metal-organic framework (MOF) namely ([Cu (INA)2]-MOF) is synthesized by ball milling and characterized using scanning electron microscopy(SEM) for the topography, microstructure, and elemental evidence determination, powdered X-ray diffraction (XRD) for the crystallinity measurement, thermogravimetric (TG) analysis was performed to de...

This study investigates the facile and rapid detection of mercury ions using silica–silver core–shell nanoparticles (SiO2–AgNPs) incorporating a paper-based colorimetric sensor strip. A strong surface plasmon resonance peak at λ = 430 nm was observed for the resultant SiO2–AgNPs. The attachment of the AgNPs to the surface of SiO2 and the deposition...

Microplastics (the term for plastics at sizes of <5 mm) might be introduced into the environment from domestic or agricultural activities or from the breakdown of plastic pieces, particles, and debris that are bigger in size. Their presence in the aquatic environment has caused accumulation problems, as microplastics do not easily break down and ca...

agonists are a class of synthetic phenylethanolamine compounds that were originally designed to reduce asthma and chronic obstructive pulmonary disease. They remain widely used but unfortunately, misuse in animal farming and sports activities due to their huge medical and economic benefits. As a result, they have been found in a variety of matrices...

Non-biodegradable plastics are an unresolved issue in solid waste management as recycling them is expensive. This study focused on formulating a biodegradable gellan gum (GG) membrane embedded with multiwalled carbon nanotubes (MWCNTs) as the adsorbent in the micro-solid phase extraction (µ-SPE) of selected polycyclic aromatic hydrocarbons (PAHs),...

In this study, the ingestion of microplastics by the deposit-feeding polychaete Namalycastis sp. in the estuarine area of the Setiu Wetlands, Malaysia was confirmed. Samples were collected from six stations, covering the wetland from the south to the north, bimonthly between November 2016 and November 2017. Microplastics were extracted from polycha...

Purpose of Review Adsorbent-based microextraction is a dynamic and simple sample preparation that allows for simultaneous extraction and enrichment of targeted analytes from a sample matrix. Its versatility, efficiency, and compliance with green analysis have contributed to its popularity against conventional solid-phase extraction. This review foc...

This study reports the distribution of microplastics (MPs) in surface water and estuarine sediments in South and North Setiu Wetland in the South China Sea. Sampling was conducted bimonthly for one year from November 2016 to November 2017, including the northeast and southwest monsoons. Water surface and sediment samples were collected from six dif...

Sample pre-treatment is often the bottleneck in an analytical process. Due to the drawbacks of conventional sample pre-treatment methods, microextraction utilizing lower amounts of adsorbents and organic solvents are therefore favoured. A micro-solid phase extraction (μ-SPE) technique coupled with gas chromatography-flame ionization detection (GC-F...

The extraction efficiency of stimulant drug, namely caffeine, was investigated using a 2 3 central composite design. The values of optimum extraction condition were set at 468 µL of 1-dodecanol, 1 piece of effervescent tablet, and 22 °C of extraction temperature. An enrichment factor was calculated as 72 for 80 mL water sample. The run time was con...

Microplastic pollutes water, land, air, and groundwater environments not only visually but also ecologically for plants, animals, and humans. Microplastic has been reported to act as vectors by sorbing pollutants and contributing to the bioaccumulation of pollutants, particularly in marine ecosystems, organisms, and subsequently food webs. The inev...

Background and Aim While dietary exposure to microplastics is increasingly recognized, it is unknown if ingested plastics remain within the digestive tract. We aimed to examine human colectomy specimens for microplastics and to report the characteristics as well as polymer composition of the particles. Methods Colectomy samples were obtained from...

Bare silver particles are widely used as the catalyst in the degradation of azo dyes. But, the performance of bare silver particles has been known to have limitations compared to their core-shell nanostructure. Herein, this study aims to reveal the potential of silica-silver core-shell nanoparticles to act as a catalyst in the catalytic degradation...

Scientific documentation on (Microplastics) MPs abundance in Malaysian waters is still limited and not fully understood. In this study, MPs occurrence in Sungai Dungun, Terengganu, Peninsular Malaysia was analysed. Sampling method was based on sieving 200 µm of bulk water to collect surface water samples from five sites in the vicinity of potential...

Tropical mangrove swamps are commonly characterized by dense networks of tidal channels that may show pronounced meandering and dendritic patterns. Channel meanders are sometimes accompanied by cutoffs, and, like classical fluvial meanders, record changes in hydrology and sedimentation over time. Channel meandering can, thus, be an important proces...

This special issue is a compilation of research papers presented during the 2019 Universiti Malaysia Terengganu Annual Symposium (UMTAS2019), held from July 23 to 25, 2019, organized by the Faculty of Science and Marine Environment (previously known as the School of Marine and Environmental Sciences). The issue aims to reflect on the current state...

A rapid and straightforward method based on effervescent-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet (HPLC-UV) detection for preconcentration of ketoprofen in water samples was developed. The extraction efficiency of ketoprofen drug was investigated using 2 3 central composite d...

Contamination of low molecular weights polycyclic aromatic hydrocarbons (PAHs) is common in beverage and water. This could pose a health risk to those beverage lovers when they consume the products. Phenanthrene (PHE) is one of the low molecular weights PAHs that consists of three benzene rings in the molecular structure. In this study, PHE was cho...

The occurrence of caffeine residue in Malaysian waters was successfully studied. The micropollutant abundance was recorded for three selected main rivers namely Terengganu, Ibai and Setiu which are located in Terengganu, Peninsular Malaysia. Surface water samples were taken twice in September and November 2018 from 15 sampling stations. Caffeine re...

Tropical mangrove swamps are commonly characterized by dense networks of tidal channels that may show pronounced meandering and dendritic patterns. Channel meanders are sometimes accompanied by cut offs, and, like classical fluvial meanders, record changes in hydrology and sedimentation over time. Channel meandering can, thus, be an important proce...

Tropical mangrove swamps are commonly characterized by dense networks of tidal channels that may show pronounced meandering and dendritic patterns. Channel meanders are sometimes accompanied by cut offs, and, like classical fluvial meanders, record changes in hydrology and sedimentation over time. Channel meandering can, thus, be an important proce...

Tropical mangrove swamps are commonly characterized by dense networks of tidal channels that may show pronounced meandering and dendritic patterns. Channel meanders are sometimes accompanied by cut offs, and, like classical fluvial meanders, record changes in hydrology and sedimentation over time. Channel meandering can, thus, be an important proce...

An analytical method based on solid-phase extraction (SPE) combined with high performance liquid chromatography-photometric diode array (HPLC-PDA) was developed to determine 4-octylphenol (4-OP) and 4-nonylphenol (4-NP) in river water samples. The optimum SPE working conditions were secured with 200 mL sample loading and eluted with 10 mL of methan...

Bisphenol A (BPA) is a xenoestrogen that widely used in manufacture of plastics. Concern is mounting up when the application of BPA is widespread. A simple sample pre-treatment technique termed membrane-protected liquid phase microextraction (MP-LPME) combined with high performance liquid chromatography (HPLC)-fluorescence detection (FD) was develo...

This study report the optimal condition of an extraction method for caffeine residue analysis in water. C18 was impregnated with cellulose triacetate by using a solution casting method to produce a thin film. Optimization work was performed based on a 23-full factorial central composite design, which was subjected to salt addition, extraction time,...

Bisphenol A (BPA) is a synthetic chemical widely applied as the monomer in the manufacture of polycarbonate plastics and epoxy resins. In this work, a micro-solid phase extraction (μ-SPE) technique using multi-walled carbon nanotubes (MWCNTs)-reinforced agarose film function as an adsorbent coupled with high performance liquid chromatography-fluore...

Silica-silver core-shell nanoparticles have received tremendous interests in various applications compared to the bare silver nanoparticles due to several important features such as exhibit higher surface area, the existence of a synergistic effect between the core and the shell, stabilize silver nanoparticles against aggregation, and easily contro...

Research work that aimed to develop the optimal condition for caffeine residue extraction in water method was successfully carried out. C18 was impregnated with cellulose triacetate (CTA) by using a solution casting method to produce a thin film. Optimisation work was constructed based on a 24 full factorial central composite design that was subjec...

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Spatial distribution of eight heavy metals (Al, Fe, Mn, Zn, Pb, Cu, Co, Cd) in surface sediments of northern Malacca Strait were investigated. Samples were taken from 18 stations in June, 2013. The concentrations of metals ranged between 1.70-5.75% (Al), 1.13-3.19% (Fe), 117.53-323.19 μg/g(Mn), 30.14-79.42 μg/g (Zn), 8.88-29.28 μg/g (Pb), 3.51-16.5...

The main goal of this research work is to measure the concentration levels of organochlorine residue in soil. The potential health risk of this pollutant on human was also determined. 10 samples were taken from a lowland paddy field situated in Kelantan, Malaysia. Physical parameters namely soil pH, organic carbon content, water content and particl...

A total of 50 samples of different parts (roots, stem disks, barks, trunks, twigs, and leaves) from five individuals of 20-year-old Rhizophora apiculata were sampled at Matang Mangrove Forest, Kuala Sepetang, Perak. The aims of this study were to determine the concentration of selected macroelements (K, Mg, Na, and Ca), microelements (Al, Fe, Zn, M...

The first report on the emergence of microplastic in Malaysian marine waters was documented in this study. Water samples were collected from two regions, namely Kuala Nerus and Kuantan port, as the representatives of different anthropogenic activities. Identification of microplastic was performed based on physical characteristics (colour, shape, de...

Organochlorine pesticides contain of halogenated compound, frequently used in Malaysia. It was listed as a POPs under Stockholm Convention. However, the usages still prevalent especially among the farmers which lead towards environment and human health effect. Thus, study was conducted at agriculture area to evaluate the contamination level of orga...

Charcoal powders obtained from commercially available charcoal and the open burning of palm oil, rubber, coconut, and mangrove trees were used to fabricate composite electrodes in this study. A weight portion of charcoal powder, graphite, cobalt, and polyvinyl chloride (C-C G-Co-PVC) were mixed in tetrahydrofuran (THF). The fabricated composite ele...

The concentration levels of organochlorine and organophosphorus pesticide residues in agriculture soils from paddy field were successfully investigated. Residues were isolated using the Soxhlet extraction method, following a clean-up process (SPE Florosil) and a final determination of targeted compounds performed by using a gas chromatography elect...

The concentration levels of organochlorine and organophosphorus pesticide residues in agriculture soils from paddy field were successfully investigated. Residues were isolated using the Soxhlet extraction method, following a clean-up process (SPE Florosil) and a final determination of targeted compounds performed by using a gas chromatography elect...

A (PDMS)-coated stir bar was prepared for a glass jacket-free stir bar sorptive extraction (SBSE) configuration by adhesion technique for the extraction of triazine herbicides prior to quantification using a gas chromatography-flame ionization detector (GC-FID). A central composite design (CCD) was used in the optimization of extraction and desorpt...

Chitosan and its derivatives namely oleoyl chitosan, oleoyl methylene phosphonic chitosan and methylene phosphonic chitosan as potential sorbents to clean up the residual oil were successfully evaluated. Batch experiment technique was employed to identify the best sorbent. The main factors affecting the sorption namely the initial concentration of...

In this study, a charcoal base metallic composite electrode which is low in cost and effective to treat wastewater from landfill leachate by electrochemical oxidation technique has been fabricated. The charcoal base metallic composite electrode was prepared by mixing together a weighed portion of charcoal, graphite and metals powder in different co...

The presence of microplastics (<1 mm) in wild and cage-cultured Asian sea bass (Lates calcarifer) was successfully studied. Fish samples were collected from Setiu Wetlands in October 2016. Microplastics were isolated from fish samples using the alkaline solution method (10 M of NaOH solution). Microplastics were sorted visually according to their s...

The presence of microplastics (<1 mm) in wild and cage-cultured Asian sea bass (Lates calcarifer) was successfully studied. Fish samples were collected from Setiu Wetlands in October 2016. Microplastics were isolated from fish samples using the alkaline solution method (10 M of NaOH solution). Microplastics were sorted visually according to their s...

This paper discusses an analytical method namely solid phase extraction that is used to separate caffeine residue present in water samples. The developed method reported is in the aspect of sample extraction, mode operation, and selection of detector, figure of merit on method performance and analysis of real samples. Sorbents namely C18 and hydrop...

Pesticides have been used extensively by the farmers in Malaysia during the last few decades.As Organochlorine (OCPs) and organophosphorus (OPPs) pesticides have been used commonly in the agriculture field, a straightforward and efficient method of extraction for pesticides using solid phase extraction (SPE) have been developedfordetection of OCPs...

A new analytical method development based on solid phase extraction (SPE) combined with high performance liquid chromatography (HPLC) was carried out. The optimum working conditions were obtained based on selection of 250 mL sample loading, 0.25 μL methanol as reconstitution solvent, 100% methanol as mobile phase and 270 nm as the optimum wavelengt...

Soil contamination is one of the sensitive issue in agricultural region of Cameron Highlands, Malaysia, which is a largest vegetable producer. Organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs) and pyrethroids pesticides (PYRs) concentrations were measured in 35 soil samples of selected crops. Among OCPs, the average concentration...

The extraction procedure for determination of low level mercury using solid phase microextraction was successfully carried out. Design of experimental works using factorial design and central composite design were applied to screen and predict the optimum condition for extraction step. In this study, variables namely concentration level (5 % m/v) a...

Hydrochemistry variation in water quality of Cempaka Lake was successfully evaluated. Data sets were tested subject to multivariate statistical analysis. Seven sampling points were selected and monitoring work was conducted monthly (May 2013–May 2014). The physicochemical parameters, namely temperature, pH, conductivity, dissolved oxygen, suspended...

A simple and sensitive analytical method has been developed employing gas chromatography coupled with electron capture detector (GC–ECD), and validated for screening and quantification of 15 pesticide residues at trace levels in cabbage, broccoli, cauliflower, lettuce, celery, spinach, and mustard. The method consists of two steps, first, to determ...

The big challenge for the detection of pharmaceutical residues in water samples is the type of ionization mode in terms of positive or negative ionization which plays an important role to identify and quantify the analytes using liquid chromatography/mass spectrometry. An analytical method was applied to analysis of gliclazide (diabetic drug) in...

An experimental design methodology was performed in the optimization of removal of malachite green dye by multi-walled carbon nanotubes. A Central Composite Design (25) was chosen to develop a mathematical model and determine the optimum condition for adsorption of malachite green by carbon nanotubes. Five experimental factors, namely initial dye c...

Extraction procedure for determination of caffeine in water with aided experimental design was successfully optimized. Three variables, namely pH sample, flow rate and elution volume were tested during this study using 23 full factorial of central composite design. An optimum working condition was suggested at pH sample (6.4), flow rate (1.2 ml/min...

A sensitive direct immersion solid phase microextraction technique coupled with gas chromatography-mass spectrometry (SPME-GC-MS) was optimized and validated for analysis of triazines in drinking water. Preliminary evaluation of fibre materials indicated that carbowax-divinylbenzene was better than poly-dimethyl siloxane-divinylbenzene thus it was...

The small tributaries to upstream Langat of Peninsular Malaysia play an important role to water quality in downstream. This study was carried out to investigate the indicator pollution and identify the potential sources of pollutants using multivariate chemometric techniques. Sampling campaign was conducted on monthly basis from January-June, 2015,...

Characterization of hydrochemistry changes in Johor Straits within 5years of monitoring works was successfully carried out. Water quality data sets (27 stations and 19 parameters) collected in this area were interpreted subject to multivariate statistical analysis. Cluster analysis grouped all the stations into four clusters ((Dlink/Dmax)×100<90) a...

An assessment of hydrological conditions on freshwater resource in Langkawi Islands was successfully carried out. Twenty six stations were chosen during scientific expedition involving six main zones namely Lubuk Semilang, Biro Tata Negara Camp, Durian Perangin, Kisap River, Gunung Raya and selected rivers in downstream. Surface water samples were...

A comparison of derivatization step influence on the method extraction of mercury species has been carried out. Experimental design generated by using central composite design was used to optimize the extraction parameters. Signal response of targeted analytes, which accounts as sum of peak areas has shown maximum response (y = 276920, in-matrix de...

This study aimed to assess the environmental situation of 18 organochlorine pesticides (OCPs), of which some are members of Persistent Organic Pollutants (POPs) in the sediment of an intensive agriculture area as well as popular tourism destination of Cameron Highlands, Malaysia. A total of 56 surface sediment samples were collected at eight select...

In this study, determination of mercury species in water by headspace solid-phase microextraction (HS-SPME) has been developed. The extraction procedure consisted of screened using factorial design and followed by optimization using two level central composite designs. An optimum working condition was obtained at 22.5 °C after 20 min, pH 4 and stir...

Comparative study of trace level of extracted mercury in different types of water was successfully carried out. Data sets of batch samples were grouped in two clusters (C I; 4, C II; 4) to represent similarity of data structure under optimized and direct extraction procedure respectively. Similarity level for inter batch samples (optimized procedur...

The present work reports the occurrence and monitoring of 11 pharmaceuticals (i.e., caffeine, prazosin, enalapril, carbamazepine, nifedipine, gliclazide, levonorgestrel, simvastatin, hydrochlorothiazide, diclofenac-Na and mefenamic acid) in surface water and in the influent and effluent of sewage treatment plants (STPs) and hospitals (HSPs). A tota...

The present work reports the occurrence and monitoring of 11 pharmaceuticals (i.e., caffeine, prazosin, enalapril, carbamazepine, nifedipine, gliclazide, levonorgestrel, simvastatin, hydrochlorothiazide, diclofenac-Na and mefenamic acid) in surface water and in the influent and effluent of sewage treatment plants (STPs) and hospitals (HSPs). A tota...