Displaying publications 41 - 60 of 142 in total

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  1. Fulltext Effects of Flower and Fruit Extracts of Melastoma malabathricum Linn. on Growth of Pathogenic Bacteria: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium
    Che Omar SN, Ong Abdullah J, Khairoji KA, Chin Chin S, Hamid M
    Evid Based Complement Alternat Med, 2013;2013:459089.
    PMID: 23662136 DOI: 10.1155/2013/459089
    Melastoma malabathricum Linn. is a shrub that comes with beautiful pink or purple flowers and has berries-like fruits rich in anthocyanins. This study was carried out with the aim to evaluate the inhibitory activities of different concentrations of the M. malabathricum Linn. flower and fruit crude extracts against Listeria monocytogenes IMR L55, Staphylococcus aureus IMR S244, Escherichia coli IMR E30, and Salmonella typhimurium IMR S100 using the disc diffusion method. The lowest concentrations of the extracts producing inhibition zones against the test microorganisms were used to determine their minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). In addition, the growth of Listeria monocytogenes IMR L55 and Staphylococcus aureus IMR S244 grown in medium supplemented with the respective extracts at different temperatures (4°C, 25°C, and 37°C) and pHs (4, 6, 7, and 8) was determined.
  2. Fulltext Voltammetric determination of palmitic acid by electrode modified with reduced graphene oxide
    Ching CB, Abdullah J, Yusof NA
    J Food Sci Technol, 2022 Mar;59(3):1053-1062.
    PMID: 35153325 DOI: 10.1007/s13197-021-05109-1
    Palm oil is one of the most produced and traded vegetable oils in the world recently. The quality of palm oil is very important to be examined and one of the quality indices is free fatty acid (FFA) content. Thus, in this study, an electrochemical technique for the determination of FFA as alternative to conventional method (titration method) has been explored. The electrochemical method was developed based on electrochemically reduced graphene oxide (rGO) deposited onto screen printed carbon electrode (SPCE) via drop-casting technique. The modified electrode was characterized by physico-chemical and electrochemical methods, respectively. The voltammetric behaviour of 2-methyl-1,4-naphthaquinone (VK3) in the presence of palmitic acid at the modified electrode was investigated in an acetonitrile/water (3:1) mixture containing 2.5 M lithium perchlorate (LiClO4). The electrochemical detection of palmitic acid was based on the voltammetric reduction of VK3 to form corresponding hydroquinone which is proportional to the concentration of palmitic acid. Under optimum condition, the developed method showed a good linear relationship in the concentration ranging from 0.192 mM to 0.833 mM with the detection limit of 0.079 mM. The developed sensor illustrates high sensitivity and rapid detection towards determination of FFA content in palm oil.
  3. Label-free optical spectroscopy for characterizing binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite towards nickel ion
    Daniyal WMEMM, Fen YW, Abdullah J, Sadrolhosseini AR, Saleviter S, Omar NAS
    Spectrochim Acta A Mol Biomol Spectrosc, 2019 Apr 05;212:25-31.
    PMID: 30594850 DOI: 10.1016/j.saa.2018.12.031
    Surface plasmon resonance (SPR) is a label-free optical spectroscopy that is widely used for biomolecular interaction analysis. In this work, SPR was used to characterize the binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite (CTA-NCC/GO) towards nickel ion. The formation of CTA-NCC/GO nanocomposite has been confirmed by FT-IR. The SPR analysis result shows that the CTA-NCC/GO has high binding affinity towards Ni2+ from 0.01 until 0.1 ppm with binding affinity constant of 1.620 × 103 M-1. The sensitivity for the CTA-NCC/GO calculated was 1.509° ppm-1. The full width at half maximum (FWHM), data accuracy (DA), and signal-to-noise ratio (SNR) have also been determined using the obtained SPR curve. For the FWHM, the value was 2.25° at 0.01 until 0.08 ppm and decreases to 2.12° at 0.1 until 10 ppm. The DA for the SPR curves is the highest at 0.01 until 0.08 ppm and lowest at 0.1 until 10 ppm. The SNR curves mirrors the curves of SPR angle shift where the SNR increases with the Ni2+ concentrations. For the selectivity test, the CTA-NCC/GO has the abilities to differentiate Ni2+ in the mixture of metal ions.
  4. Fulltext X-ray Photoelectron Spectroscopy Analysis of Chitosan-Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications
    Daniyal WMEMM, Fen YW, Saleviter S, Chanlek N, Nakajima H, Abdullah J, et al.
    Polymers (Basel), 2021 Feb 02;13(3).
    PMID: 33540931 DOI: 10.3390/polym13030478
    In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan-graphene oxide (chitosan-GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co2+). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR-chitosan-GO thin film, while for CdS QD-chitosan-GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian-Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan-GO-based thin films were able to detect Co2+ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co2+ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR-chitosan-GO thin film contributed more important role for the reaction with Co2+, as in agreement with the SPR results.
  5. A systematic review of the computerized tools and digital techniques applied to fabricate nasal, auricular, orbital and ocular prostheses for facial defect rehabilitation
    Farook TH, Jamayet NB, Abdullah JY, Rajion ZA, Alam MK
    J Stomatol Oral Maxillofac Surg, 2020 Jun;121(3):268-277.
    PMID: 31610244 DOI: 10.1016/j.jormas.2019.10.003
    A systematic review was conducted in early 2019 to evaluate the articles published that dealt with digital workflow, CAD, rapid prototyping and digital image processing in the rehabilitation by maxillofacial prosthetics. The objective of the review was to primarily identify the recorded cases of orofacial rehabilitation made by maxillofacial prosthetics using computer assisted 3D printing. Secondary objectives were to analyze the methods of data acquisition recorded with challenges and limitations documented with various software in the workflow. Articles were searched from Scopus, PubMed and Google Scholar based on the predetermined eligibility criteria. Thirty-nine selected papers from 1992 to 2019 were then read and categorized according to type of prosthesis described in the papers. For nasal prostheses, Common Methods of data acquisition mentioned were computed tomography, photogrammetry and laser scanners. After image processing, computer aided design (CAD) was used to design and merge the prosthesis to the peripheral healthy tissue. Designing and printing the mold was more preferred. Moisture and muscle movement affected the overall fit especially for prostheses directly designed and printed. For auricular prostheses, laser scanning was most preferred. For unilateral defects, CAD was used to mirror the healthy tissue over to the defect side. Authors emphasized on the need of digital library for prostheses selection, especially for bilateral defects. Printing the mold and conventionally creating the prosthesis was most preferred due to issues of proper fit and color matching. Orbital prostheses follow a similar workflow as auricular prosthesis. 3D photogrammetry and laser scans were more preferred and directly printing the prosthesis was favored in various instance. However, ocular prostheses fabrication was recorded to be a challenge due to difficulties in appropriate volume reconstruction and inability to mirror healthy globe. Only successful cases of digitally designed and printed iris were noted.
  6. Endoscopic neurosurgery: report of the first five cases done in Malaysia using the Caemaert-Abdullah method
    Farouk A, Abdullah J
    Minim Invasive Neurosurg, 1998 Jun;41(2):74-8.
    PMID: 9651914
    The first endoscopic procedure done in Malaysia using the Caemaert-Abdullah method is reported and the followup results showed an excellent neurosurgical outcome. A 16-year-old girl with an aqueduct stenosis was operated on using a free-hand, computer-assisted endoscopic method where a third ventriculostomy was done. This was the first case being carried out in the Hospital Universiti Sains Malaysia. The next two cases were a suprasellar pituitary cyst in an elderly man and a child with an obstructive hydrocephalus who was previously shunted which became infected. Both endoscopic procedures, extirpation of the cyst using a Nd:Yag laser and a third ventriculostomy, respectively, were done under general anaesthesia in the supine position. Follow-up revealed a transient diabetes insipidus in all three cases up to 48 hours after the operation which resolved spontaneously. The fourth case involved an endoscopic removal of retained ventricular catheter after rectal migration of a shunt in an eight-year-old girl with congenital hydrocephalus. The fifth was a free-hand endoscopy with perforation of multiple brain septae in a ten-month-old baby with hydrocephalus secondary to meningitis. The final outcomes for all the cases were favourable hence we conclude that endoscopic neurosurgery is a safe procedure and hope that more neurosurgeons will continue to use this method, especially for the management of intraventricular cyst and hydrocephalus and especially in South East Asia.
  7. Fulltext Biosensor Based on Tyrosinase Immobilized on Graphene-Decorated Gold Nanoparticle/Chitosan for Phenolic Detection in Aqueous
    Fartas FM, Abdullah J, Yusof NA, Sulaiman Y, Saiman MI
    Sensors (Basel), 2017 May 16;17(5).
    PMID: 28509848 DOI: 10.3390/s17051132
    In this research work, electrochemical biosensor was fabricated based on immobilization of tyrosinase onto graphene-decorated gold nanoparticle/chitosan (Gr-Au-Chit/Tyr) nanocomposite-modified screen-printed carbon electrode (SPCE) for the detection of phenolic compounds. The nanocomposite film was constructed via solution casting method. The electrocatalytic activity of the proposed biosensor for phenol detection was studied using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Experimental parameters such as pH buffer, enzyme concentration, ratio of Gr-Au-Chit, accumulation time and potential were optimized. The biosensor shows linearity towards phenol in the concentration range from 0.05 to 15 μM with sensitivity of 0.624 μA/μM and the limit of detection (LOD) of 0.016 μM (S/N = 3). The proposed sensor also depicts good reproducibility, selectivity and stability for at least one month. The biosensor was compared with high-performance liquid chromatography (HPLC) method for the detection of phenol spiked in real water samples and the result is in good agreement and comparable.
  8. Uniaxial and Multiaxial Fatigue Life Prediction of the Trabecular Bone Based on Physiological Loading: A Comparative Study
    Fatihhi SJ, Harun MN, Abdul Kadir MR, Abdullah J, Kamarul T, Öchsner A, et al.
    Ann Biomed Eng, 2015 Oct;43(10):2487-502.
    PMID: 25828397 DOI: 10.1007/s10439-015-1305-8
    Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p 
  9. Fulltext Advances in Aptamer-Based Biosensors and Cell-Internalizing SELEX Technology for Diagnostic and Therapeutic Application
    Gan Z, Roslan MAM, Abd Shukor MY, Halim M, Yasid NA, Abdullah J, et al.
    Biosensors (Basel), 2022 Oct 25;12(11).
    PMID: 36354431 DOI: 10.3390/bios12110922
    Aptamers are a group of synthetic single-stranded nucleic acids. They are generated from a random library of single-stranded DNA or RNA by a technology named systematic evolution of ligands by exponential enrichment (SELEX). SELEX is a repetitive process to select and identify suitable aptamers that show high affinity and specificity towards target cells. Great strides have been achieved in the design, construction, and use of aptamers up to this point. However, only a small number of aptamer-based applications have achieved widespread commercial and clinical acceptance. Additionally, finding more effective ways to acquire aptamers with high affinity remains a challenge. Therefore, it is crucial to thoroughly examine the existing dearth and advancement in aptamer-related technologies. This review focuses on aptamers that are generated by SELEX to detect pathogenic microorganisms and mammalian cells, as well as in cell-internalizing SELEX for diagnostic and therapeutic purposes. The development of novel aptamer-based biosensors using optical and electrical methods for microbial detection is reported. The applications and limitations of aptamers are also discussed.
  10. Fulltext Neonatal posterior fossa haemorrhage associated with vacuum extractor
    Ghani AR, Prakash RG, Abdullah J
    Med J Malaysia, 2006 Mar;61(1):100-2.
    PMID: 16708744 MyJurnal
    We report one case of posterior fossa intracranial haemorrhage in a full-term Malay baby boy following vacuum assisted delivery. The patient, a term baby boy was delivered by a vacuum extraction and later developed signs of increased intracranial pressure 72 hours after birth. Computed tomography (CT) of the brain showed a posterior fossa intracranial haemorrhage with acute obstructive hydrocephalus. He was initially treated with isolated ventricular shunting which later caused an upward cerebellar herniation. An immediate suboccipital craniectomy for evacuation of cerebellar haematoma was performed which resulted in a gradual recovery.
  11. Giant nerve sheath tumour: report of six cases
    Ghani AR, Ariff AR, Romzi AR, Sayuthi S, Hasnan J, Kaur G, et al.
    Clin Neurol Neurosurg, 2005 Jun;107(4):318-24.
    PMID: 15885392
    Giant nerve sheath tumour is a rare tumour originating from the nerve sheath. It differs from the conventional nerve sheath tumour only by the size these tumours can reach. There are two main type of tumours that occur in the nerve sheath which include neurofibroma and schwannoma. The current views are that schwannomas arise from the progenitor of the schwann cell. Whereas the neurofibroma series probably arise from a mesenchymal origin closer to a fibroblast. We report on six cases of nerve sheath tumour that occur in the spinal and paraspinal region that presented to us over a 5 year period.
  12. Fulltext Recurrent paediatric supratentorial extraventricular ependymoma associated with genetic mutation at exon 4 of p53 gene
    Ghani AR, Abdullah JM, Ghazali M, Ahmad F, Ahmad KA, Madhavan M
    Singapore Med J, 2008 Jul;49(7):e192-4.
    PMID: 18695856
    Recurrent supratentorial extraventricular ependymoma in a four-year-old Malay boy treated twice surgically in combination with cranial radiotherapy is reported. He presented with symptoms of raised intracranial pressure and a history of focal seizure. Computed tomography of the brain showed a left supratentorial extraventricular cystic lesion causing a mass effect. The tumour histology was ependymoma (WHO grade II). The clinical course, radiological characteristics and management of this tumour are discussed. Molecular genetic analysis of p53 and p27 genes revealed substitution of nucleotide G to C at location nucleotide 12139, exon 4 of gene p53. No alteration was detected at exon 5-6 and 8 of p53 gene and exon 1 and 2 of p27 gene.
  13. The use of magnetic resonance phase-contrast cine in Chiari malformation with syringomyelia
    Goh CH, Hamzah MR, Kandasamy R, Ghani ARI, Wong SH, Idris Z, et al.
    Med J Malaysia, 2020 11;75(6):666-671.
    PMID: 33219175
    INTRODUCTION: Chiari malformation (CM) is a disorder of mesodermal origin and is commonly associated with syringomyelia. Foramen magnum decompression is the first-line of standard treatment in symptomatic patients with a confirmed radiographic diagnosis. Magnetic resonance (MR) cine allows accurate evaluation of cerebrospinal fluid (CSF) physiology at the craniovertebral junction but often this is under-utilised in Malaysia.

    METHODS: In this series, we looked into nine cases of CM with syringomyelia from clinical and radiological perspective before and after surgery. The radiological parameters were herniated tonsillar length, syrinx: cord ratio, syrinx length and diameter. Flow velocity and morphologic changes in Chiari were illustrated.

    RESULTS: Seven patients showed either reduction in syrinx length, syrinx: cord ratio or both postoperatively. Clinical recovery somewhat varied in motor and sensory symptoms. Four patients gained better functional grade in modified Rankin scale (MRS) while the rest remained similar. The study highlighted the advantage of CSF flow dynamics information over MR anatomical radiographic improvement in addressing the neurologic and functional recovery. We also discussed the practicality of cine sequence in preoperative patient selection, syrinx analysis and postoperative flow evaluation in anticipation of clinical outcome.

    CONCLUSION: Phase-contrast cine MRI is a useful tool dictated by resource availability. We recommend its routine use in preoperative analysis and subsequent observational follow-up after surgery.

  14. Acute toxicity study of the standardized methanolic extract of Mitragyna speciosa Korth in rodent
    Harizal SN, Mansor SM, Hasnan J, Tharakan JK, Abdullah J
    J Ethnopharmacol, 2010 Sep 15;131(2):404-9.
    PMID: 20643198 DOI: 10.1016/j.jep.2010.07.013
    ETHNOPHARMACOLOGICAL RELEVANCE: Mitragyna speciosa Korth (ketum) is widely used in Malaysia as a medicinal agent for treating diarrhea, worm infestations and also acts as an analgesic and antipyretic.
    AIM: The aim of the study is to determine the acute toxicity of Mitragyna speciosa Korth standardized methanol extract in vivo in 4-weeks-old Sprague-Dawley rats.
    METHODOLOGY: Rats were orally administrated single dose of 100, 500 and 1000 mg/kg Mitragyna speciosa Korth standardized methanol extract and the control group received 430 mg/kg of morphine orally. There were 10 rats in each group. All animals were sacrificed after 14 days of treatment. Eight parameters were tested: cage side observation, body weight measurement, food and water consumption, blood pressure, absolute and relative organ weight, hematology, biochemical analysis and histopathology, to look for evidence of toxicity.
    RESULT: No mortality was noted after 14 days of treatment. In general, behavior, food and water consumption, hematological studies and organ weights showed no significant changes. The standardized methanol extraction of Mitragyna speciosa Korth increased rat blood pressure (systolic: 147.4+/-1.01, 131.64+/-4.94 and 137.8+/-4.46) after an hour of 100, 500 and 1000 mg/kg doses, respectively. Biochemical studies showed significant elevation of ALT, AST, albumin, triglycerides, cholesterol and albumin (p>0.05), at all levels of doses. But, nephrotoxicity evidenced by elevated creatinine was seen only at a dose of 1000 mg/kg. Histological examination showed congestion of sinusoids, hemorrhage hepatocytes, fatty change, centrilobular necrosis and increased number of Kuppfer cells in the liver of all Mitragyna speciosa Korth standardized methanol extract treated groups.
    CONCLUSION: Oral administration of standardized methanolic extraction of Mitragyna speciosa Korth resulted in increasing rat blood pressure after an hour of drug administration. The highest dose of extract also induced acute severe hepatotoxicity and mild nephrotoxicity. However, Mitragyna speciosa Korth shows no effects on body weight, food and water consumption, absolute and relative organ weight and also hematology parameters.
  15. Fulltext Appraisal of clinical profile and management of juvenile nasopharyngeal angiofibroma in malaysia
    Hassan S, Abdullah J, Abdullah B, Jihan Wd S, Jaafar H, Abdullah S
    Malays J Med Sci, 2007 Jan;14(1):18-22.
    PMID: 22593647 MyJurnal
    Juvenile nasopharyngeal angiofibroma (JNA) is a benign but locally invasive tumour. Patients are usually in their adolescent age and present with epistaxis and nasal blockage. Diagnosis is based on clinical evaluation and the C.T. scan findings. Pre-operative superselective embolisation (SSE) and surgical excision is the treatment of choice. The out patient clinic of ORL-HNS hospital of University Science Malaysia received 25 referrals, all male, majority between 9-13 years of age and few adolescents. Clinically the patients were consistent with symptoms of recurrent epistaxis and nasal blockage. They reported from October 1998 to October 2001 from with in the state of Kelantan and the nearby states of Pahang, Kedah and Terenganu. Diagnosis was mostly made on typical radiological findings and the tumours were classified accordingly into four stages. SSE and surgical excision was carried out in all cases. Regular follow-up helped us to identify early recurrences which were treated with salvage surgery or radiotherapy in one case with extensive intracranial extension. A retrospective review of presenting features, diagnostic difficulties, surgical approaches and its outcome is presented. Maxillary swing procedure performed in three cases as a new surgical option in the management of JNA is also discussed.
    Study site: ENT clinic, Hospital Universiti Sains Malaysia (HUSM), Kelantan, Malaysia
  16. Fulltext Identification and analysis of expressed sequence tags present in xylem tissues of kelampayan (Neolamarckia cadamba (Roxb.) Bosser)
    Ho WS, Pang SL, Abdullah J
    Physiol Mol Biol Plants, 2014 Jul;20(3):393-7.
    PMID: 25049467 DOI: 10.1007/s12298-014-0230-x
    The large-scale genomic resource for kelampayan was generated from a developing xylem cDNA library. A total of 6,622 high quality expressed sequence tags (ESTs) were generated through high-throughput 5' EST sequencing of cDNA clones. The ESTs were analyzed and assembled to generate 4,728 xylogenesis unigenes distributed in 2,100 contigs and 2,628 singletons. About 59.3 % of the ESTs were assigned with putative identifications whereas 40.7 % of the sequences showed no significant similarity to any sequences in GenBank. Interestingly, most genes involved in lignin biosynthesis and several other cell wall biosynthesis genes were identified in the kelampayan EST database. The identified genes in this study will be candidates for functional genomics and association genetic studies in kelampayan aiming at the production of high value forests.
  17. Neuronavigation-guided endoscopic management of a pineal region tumour with obscured floor of the third ventricle: case report
    Idris Z, Ghani AR, Idris B, Muzaimi M, Awang S, Pal HK, et al.
    Minim Invasive Neurosurg, 2011 Jun;54(3):125-7.
    PMID: 21863520 DOI: 10.1055/s-0031-1277198
    Shunt surgery is frequently chosen to manage periventricular metastasis of pineal region tumours which obscured the floor of the third ventricle. However, this procedure falls short due to distant metastasis. Neuronavigation-guided endoscopic surgery offers a viable alternative.
  18. Distribution of prosaposin mRNA in the central nervous system of the pigeon (Columba livia)
    Islam MR, Abdullah JM, Atoji Y
    Anat Histol Embryol, 2013 Aug;42(4):257-65.
    PMID: 22994540 DOI: 10.1111/ahe.12009
    Bioassay and immunohistochemical studies have detected the presence of prosaposin in the central nervous system (CNS) of mammals. Here, first time, we have determined the partial cDNA sequence of pigeon prosaposin and mapped the distribution of its mRNA in the pigeon CNS. The predicted amino acid sequence of pigeon prosaposin showed 93 and 60% identity to chicken and human prosaposin, respectively. In situ hybridization, autoradiograms showed that the prosaposin mRNA expression was found in the olfactory bulb, prepiriform cortex, Wulst, mesopallium, nidopallium, hippocampal formation, thalamus, tuberis nucleus, pre-tectal nucleus, nucleus mesencephalicus lateralis, pars dorsalis, nucleus isthmi, pars parvocellularis and magnocellularis, Edinger-Westphal nucleus, optic tectum, cerebellar cortex and nuclei, vestibular nuclei and gray matter of the spinal cord. These results suggest that the cDNA sequence of pigeon prosaposin is comparable to other vertebrates, and the general distribution pattern of prosaposin mRNA resembles those are found in mammals.
  19. Fulltext Electrochemical Detection of Arsenite Using a Silica Nanoparticles-Modified Screen-Printed Carbon Electrode
    Ismail S, Yusof NA, Abdullah J, Abd Rahman SF
    Materials (Basel), 2020 Jul 16;13(14).
    PMID: 32708531 DOI: 10.3390/ma13143168
    Arsenic poisoning in the environment can cause severe effects on human health, hence detection is crucial. An electrochemical-based portable assessment of arsenic contamination is the ability to identify arsenite (As(III)). To achieve this, a low-cost electroanalytical assay for the detection of As(III) utilizing a silica nanoparticles (SiNPs)-modified screen-printed carbon electrode (SPCE) was developed. The morphological and elemental analysis of functionalized SiNPs and a SiNPs/SPCE-modified sensor was studied using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The electrochemical responses towards arsenic detection were measured using the cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) techniques. Under optimized conditions, the anodic peak current was proportional to the As(III) concentration over a wide linear range of 5 to 30 µg/L, with a detection limit of 6.2 µg/L. The suggested approach was effectively valid for the testing of As(III) found within the real water samples with good reproducibility and stability.
  20. Voltammetric determination of iodide in iodized table salt using cetyltrimethylammonium bromide as ion-pairing
    Jamilan MA, Abdullah J, Alang Ahmad SA, Md Noh MF
    J Food Sci Technol, 2019 Aug;56(8):3846-3853.
    PMID: 31413410 DOI: 10.1007/s13197-019-03855-x
    In this work, voltammetric study based on cetyltrimethylammonium bromide (CTAB) as an ion-pairing agent for the determination of iodine level in iodized table salt has been explored. CTAB was used as an intermediate compound between iodide (I-) and the electrode due to its ability to dissociate to produce cetyltrimethylammonium ions ([CTA]+). The [CTA]+ with a long hydrophobic alkyl chain can be directly adsorbed onto the surface of the working electrode, and this in turns coated the electrode with cationic charge and enhance the electrode ability to bind to iodide (I-) and other molecular iodine ions. A mixture of iodide and CTAB ([CTA]+I-) was prepared and potential of 1.0 V for 60.0 s was applied to pre-concentrate the solution on the working electrode causing the [CTA]+I- to oxidize to iodine (I2). The produced I2 immediately react with chloride ion (Cl-) from the electrolyte of hydrochloric acid (HCl) to produce I2Cl- and form ion-pair with CTA+ as [CTA]+I2Cl-. The linear calibration curve of the developed method towards iodide was in the concentration range of 0.5-4.0 mg/L with sensitivity of - 1.383 µA mg/L-1 cm-2 (R2 = 0.9950), limit of detection (LOD) of 0.3 mg/L and limit of quantification (LOQ) of 1.0 mg/L, respectively. The proposed method indicates good agreement with the standard method for iodine determination with recovery range from 95.0 to 104.3%. The developed method provided potential application as a portable on-site iodine detector.
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