Displaying publications 1 - 20 of 32 in total

Abstract:
Sort:
  1. Musa Ahmad, Narayanaswamy R
    Optical fibre has been used in this study to guide a light from the light source to the probe. A disposable type probe developed in this study consist of a reagent Chrome Azurol S (CAS) immobilised on a polymeric support (XAD-2) which has been coupled to a fibre end using nylon mesh. This sensor was regenerable using fluoride solution with a limit of detection of 1.0 ´ 10-5 M, high reproducibility (relative error of < 5.0%) and can be used for Al(III) determination in water at concentration range of 1.3 ´ 10-5 M - 7.0 ´ 10-4 M. The results obtained using this sensor is comparable to the well established method such as atomic absorption spectrophotometry using graphite furnace. EDTA, phosphate, oxalate, tartrate, Cu(II), Fe(III), Be(II) and Ca(III) were found to interfere during Al(III) determination in water.
    Gentian optik telah digunakan di dalam kajilidikan ini sebagai pemandu cahaya daripada sumber cahaya kepada prob. Prob jenis bolehbuang yang dibina dalam kajian ini terdiri daripada reagen Chrome Azurol S (CAS) yang telah dipegunkan di atas penyokong polimer (XAD-2) dan dipegang olehjaring nilon. Penderia ini boleh dijanakan semula menggunakan larutan fluorida, mempunyai had pengesaran 1.0 ´ 10-5 M, kebolehulangan yang tinggi (ralat relatif < 5.0%) dan boleh digunakan untuk penentuan Al(III) dalam air pada julat kepekatan 1.3 ´ 10-5 M - 7.0 ´ 10-4 M. Keputusan analisis yang diperolehi menggunakan penderia ini adalah bolehbanding dengan kaedah yang telah diterima umum seperti spektrofotometri serapan atom mertggunakan relau grafit. EDTA, fosfat, oksalat, tartrat, Cu(II), Fe(III), Be(II) dan Ca(III) didapati menganggu semasa penentuan Al(III) di dalam air.
  2. Khor SM, Lee YH, Musa Ahmad
    A study on the design of solid-state ion sensor was carried out. The electrode used was based on Ag/AgCl and two types of Ag/AgCl electrode designs used were rod-shape and screen printed (SPE) Ag/AgCl electrodes. The assessment of the electrode response was based on anion response, especially the response of chloride ions. Apart from that, the solid-state electrodes were also assessed for their response to several cations after a photocured polymer membrane with an immobilised lipophilic salt sensitive to cations was deposited on the electrodes. The results show that the use of a poly(hydroxyl ethyl methacrylate) hydrated with a salt solution is important to replace the inner reference solution of a conventional non solid-state ion­-selective electrode if normal response of an electrode is to be obtained. The sensor response which remains near to Nernstian after undergoing membrane deposition processes by photocuring technique indicate that these solid-state ion sensors can be used for the construction of biosensors that are based on potentiometric transduction.
    Kajian rekabentuk sensor ion jenis keadaan-pepejal telah dilakukan. Elektrod yang digunakan adalah berdasarkan kepada Ag/AgCl. Rekabentuk dua jenis elektrod keadaan pepejal telah dipilih, iaitu berdasarkan elektrod Ag/AgCl jenis rod dan jenis elektrod Ag/AgCl bercetak skrin (screen printed electrode, SPE). Penilaian termasuk kajian responsnya terhadap anion, khasnya ion klorida. Di samping itu, respons elektrod keadaan-pepejal ini terhadap beberapa kation juga dilakukan setelah elektrod rod dan SPE disalutkan dengan beberapa jenis fotopolimer serta pemegunan garam lipofilik yang peka kepada kation. Hasil kajian menunjukkan penggunaan poli(hidroksi etil metakrilat) terhidrat dengan larutan garam untuk menggantikan larutan rujukan dalaman bagi elektrod pemilih ion konvensional yang bukan berbentuk keadaan-pepejal adalah penting demi menghasilkan sensor berbentuk keadaan pepejal yang bersifat normal. Ciri sensor ion yang masih bersifat hampir Nernstian walaupun telah mengalami beberapa proses fabrikasi sistem fotopolimer menunjukkan bahawa sensor keadaan-pepejal ini boleh juga digunakan dalam rekabentuk biosensor potentiometrik selain daripada sensor ion.
  3. Nur Azlinawati Md. Khlid, Musa Ahmad
    Optical sensing material for detection of pH has been prepared by immobilising phenol red in nafion membrane. Glass slides with dimension 3 in × 1 in were used as a support. The nafion membrane doped with phenol red was characterized by using uv-Visible Spectrophotometer to study the responses at different pH, repeatability and photo stability. The sensing materials were able to be used for the development of an optical pH sensor since the reagent could be successfully immobilised and produced good responses at different pH.
    Bahan sensor untuk pengesanan pH telah disediakan dengan memegunkan reagen fenol merah dalam membran nafion. Slaid kaca yang berukuran 3 in × 1 in telah digunakan sebagai penyokong. Setelah dipegunkan. membran terdop dengan reagen fenol merah dicirikan menggunakan Spektrofotometer uL-Nampak untuk mengkaji kebolehulangan. kestabilan foto dan kesan terhadap pH berbeza. Hasil kajian menunjukkan bahawa bahan ini boleh digunakan sebagai bahan sensor dalam pembinaan sensor optik pH kerana reagen berjaya dipegunkan dan memberikan rangsangan yang baik pada pH yang berbeza.
  4. Musa Ahmad, Lau MY
    This study focused on the development and optimization of a hybrid material formed from sol-gel and chitosan which could be used as a chemical sensing material. It is hoped that this new matrix can overcome certain weaknesses in sol­gel and chitosan materials. Dip-coating technique was used to prepare the film on microscope glass slide which functioned as a solid support. For optimization purposes, thymol blue was chosen as a pH indicator and was entrapped in the film. The film was characterized using uv-Visible Spectrophotometer. Morphology studies of the surface of the film were carried out using Scanning Electron Microscope (SEM). Results indicated that the most suitable solgel: chitosan ratio for hybrid formation was 60:40 after considering the surface morphology of the film, leaching, response time and also the intensities of the spectrum. Besides that, the results also show that the pH indicator could be successfully entrapped inside the hybrid film and would still retain its chemical behavior just as in solution. The sensing material was found to have good repeatability when reacted with buffer solution and showed RSD values of 4.24 % and 5.96 % in buffer solution at pH 2.0 and pH 11.0, respectively. The entrapped indicator also showed good photo stability with RSD of 5.35 % for the duration of 8 hours. However; the reproducibility of the hybrid film was quite low with a RSD value of 18.40 % and 31.22 % at wavelength of 500 nm and 600 nm, respectively due to leaching.
    [Penyelidikan ini difokuskan kepada pembangunan dan pengoptimuman bahan hibrid antara sol-gel dan kitosan untuk membentuk suatu matriks baru bagi penyediaan bahan penderia kimia yang dapat mengatasi kekurangan tertentu dalam bahan sol-gel danjuga kitosan. Teknik penyalutan celup telah digunakan untuk penyediaan filem nipis di atas penyokong slaid kaca mikroskop. Untuk tujuan pengoptimuman, timol biru dipilih sebagai penunjuk pH dan dipegunkan di dalam filem. Filem nipis dicirikan menggunakan Spektrofotometer UL-Nampak. Kajian morfologi ke atas permukaan filem pula dilakukan dengan menggunakan Mikroskop Imbasan Elektron (MIE). Keputusan yang diperolehi menunjukkan bahawa nisbah sol-gel:kitosan yang paling sesuai ialah 60:40 dengan mempertimbangkan dari segi morfologi permukaan filem, kelarutresapan, masa rangsangan dan juga keamatan spektrum. Selain itu, keputusan menunjukkan bahawa penunjuk pH berjaya dipegunkan dalam filem hibrid sol-gel-kitosan dan mampu mengekalkan sifat kimianya sebagaimana dalam larutan. Bahan penderia kimia ini didapati mempunyai kebolehulangan yang baik apabila bertindak dengan larutan penimbal dan menunjukkan nilai RSD yang baik iaitu 4.24% dan 5.96% dalam larutan penimbal pH 2.0 dan pH 11.0, masing-masingnya. Penunjuk pH terpegun turut menunjukkan kestabilan foto yang baik (RSD = 5.35%) untuk tempoh 8 jam. Walau bagaimanapun, kebolehasilan filem agak rendah dengan RSD yang bernilai 18.40% dan 31.22 % pada panjang gelombang 550 nm dan 600 nm masing-masing akibat daripada kelarut resapan].
  5. Mohd. Azwani Shah Mat Lazim, Musa Ahmad, Zuriati Zakaria, Mohd. Nasir Taib
    Artificial neural network (ANN) was used in this study to determine water turbidity by using back propagation algorithm. Three wavelengths which represent reflectance intensity for eight standard samples were used as training input. The finding from the study shows that the trained network with number of epochs of 250,000 and learning rate of 0.001 gave the lowest sum of squared error (SSE) of 0.04. ANN was able to predict the turbidity of water based on the pattern recognition of the reflectance spectrum. The architecture of optimized ANN used in this study was 3:25:1. The average prediction error was 0.02.
    [Jaringan neural tiruan (ANN) dengan lagoritma perambatan balik (BP) telah digunakan dalam kajian ini untuk menentukan kekeruhan air. Tiga panjang gelombang yang mewakili serapan bagi lapan sampel telah dipilih sebagai imput latihan. Hasil kajian menunjukkan bagi jaringan terlatih dengan bilangan ulangan latihan 250,000 dan kadar pembelajaran 0.001 telah memberikan nilai SSE yang terendah iaitu 0.04. Dalam kajian ini jaringan ANN didapati boleh menentu dan meramalkan nilai kekeruhan sample air berdasarkan corak serapan pantulan. Arkitektur yang sesuai bagi kajian ini adalah 3:25:1. Purata ralat ramalan adalah 0.02].
  6. Rita Sundari, Musa Ahmad, Lee YH
    Sains Malaysiana, 2006;35:67-73.
    An equation modeling on Sembulan river, Sabah, Malaysia, has been undertaken using a backward stepwise multiple linear regression. A good performance has been obtained using a log transformation on water quality data designated as predictors and dependent variable. The regression model is in accordance with the ANOVA result. The temperature, biochemical oxygen demand (BOD), Echerichia Coli, Pb and nitrate were described as continuous predictors, while the river location (downstream, municipal and upstream) was designated as independent string grouping variable, and the chemical oxygen demand (COD) was set up as the dependent variable. The string grouping variable was converted to its dummy variable, which in turn led to design of a three-equation model with respect to river location. The results show that BOD has a strong effect on COD, while Pb and nitrate show less effect on COD. The temperature gives little negative effect on COD, while other variables such as pH, salinity and Cd are excluded from the river modeling since they induce insignificant effects based on backward criterion probability of F-value ≥ 0.100. Using the general linear model with LSD mode, it is revealed that predictor(s) show a remarkable discriminant effect between upstream and municipal/downstream on the 0.05 level. The most effect came from salinity indicated by the canonical discriminant function based on Wilks’ lambda.
  7. Nurul Izzah Ab Rahman, Musa Ahmad
    Sains Malaysiana, 2006;35:7-10.
    Kajian pemegunan enzim peroksidase dalam membran hibrid sol-gel-kitosan untuk penyediaan transduser optik hidrogen peroksida telah dilakukan dalam pembinaan biosensor. Kajian ini merangkumi pengoptimuman nisbah sol-gel-kitosan, pencirian enzim dalam larutan bebas dan pemegunan enzim dalam hibrid sol-gel-kitosan serta penciriannya. Spektrum serapan bagi setiap pencirian ditentukan menggunakan Spektrofotometer uL-Nampak. Hasil kajian menunjukkan aktiviti enzim tidak berubah selepas pemegunan. Nisbah optimum hibrid sol-gel-kitosan adalah 4:6. Nilai sisihan piawai relatif (RSD) untuk kebolehulangan kaedah ini adalah 2.71% dan 3.76%, masing-masingnya untuk enzim bebas dan enzim terpegun.
  8. Azizul Isha, Nor Azah Yusof, Musa Ahmad, Dedy Suhendra, Wan Md. Zin Wan Yunus, Zulkarnain Zainal
    MyJurnal
    An artificial neural network (ANN) was applied for the determination of V(V) based on immobilized fatty hydroxamic acid (FHA) in poly(methyl methacrylate) (PMMA). Spectra obtained from the V(V)-FHA complex at single wavelengths was used as the input data for the ANN. The V(V)-FHA complex shows a limited linear dynamic range of V(V) concentration of 10 - 100 mg/ L. After training with ANN, the linear dynamic range was extended with low calibration error. A three layer feed forward neural network using backpropagation (BP) algorithm was employed in this study. The input layer consisted of single neurons, 30 neurons in hidden a layer and one output neuron was found appropriate for the multivariate calibration used. The network were trained up to 10000 epochs with 0.003 % learning rate. This reagent also provided a good analytical pedormance with reproducibility characters of the method yielding relative standard deviation (RSD) of 9.29% and 7.09% for V(V) at concentrations of 50 mg/ L and 200 mg/ L, respectively. The limit of detection of the method was 8.4 mg/ L.
  9. Nurul Izzaty Hassan, Musa Ahmad
    Sains Malaysiana, 2007;36:189-194.
    Analisis kuantitatif untuk penentuan kepekatan ion Al3+ dalam larutan akueus telah dilakukan menggunakan reagen alizarin red S (ARS) melalui pembentukan kompleks ARS-Al(III) yang dianalisis menggunakan kaedah spektrofotometri UL-Nampak. Kompleks ARS-Al(III) memberikan puncak serapan pada panjang gelombang 484 nm pada pH 5. Kajian kestabilan foto bagi reagen ARS memberikan nilai RSD sebanyak 0.46 %. Analisis kebolehulangan memberikan nilai RSD sebanyak 1.07 % dan 0.67 % masing-masingnya bagi kepekatan Al(III) 0.2 ppm dan 9 ppm. Gangguan kation Cu2+ dan Fe3+ pada nisbah mol 1:10 adalah minimum. Kebanyakan anion penggangu tidak memberikan kesan gangguan kecuali F- pada nisbah mol 1:1 dan 1:10. Sistem ini memberikan julat kepekatan dinamik Al3+ antara 0.1 – 1.0 ppm. Arkitektur ANN dengan bilangan neuron terlindung, bilangan kitaran dan kadar pembelajaran adalah masing-masingnya 23, 40000 dan 0.001 telah berjaya memanjangkan julat dinamik kepekatan Al(III) daripada 0.1 – 8.0 ppm. Reagen ARS berjaya dipegunkan pada permukaan ko-polimer XAD 4 dan mampu memberikan respon optik yang baik terhadap ion Al3+.
  10. Rosmawani Mohammad, Musa Ahmad, Jamaluddin Mohd Daud
    Sains Malaysiana, 2007;36:33-38.
    Potensi larutan reagen fenilfluoron untuk digunakan sebagai bahan reagen bagi pembangunan sensor optik pH dibincangkan dalam kajian ini. Reagen ini dipilih kerana ia belum pernah dilaporkan sebelum ini untuk digunakan sebagai bahan reagen bagi pembangunan sensor optik pH. Berdasarkan kajian larutan yang telah dijalankan, julat rangsangan linear pH bagi reagen fenilfluoron ialah antara pH 4–11. Perubahan warna dapat diperhatikan, iaitu warna kuning dalam asid kuat, warna oren dalam asid lemah serta bes lemah dan warna ungu dalam bes kuat. Perubahan warna yang berlaku adalah lebih kurang 5 saat. Reagen fenilfluoron mempunyai kestabilan foto yang baik dengan nilai RSD 0.33% untuk tempoh kajian selama 95 hari. Nilai RSD bagi kebolehulangan pada pH 2, pH 7 dan pH 12 adalah masing-masingnya sebanyak 2.6%, 0.9% dan 1.4%. Pemerhatian ini menunjukkan fenilfluoron mempunyai potensi yang baik untuk digunakan sebagai bahan reagen bagi pembangunan sensor optik pH.
  11. Loh KS, Lee YH, Musa A, Salmah AA, Zamri I
    Sensors (Basel), 2008 Sep 18;8(9):5775-5791.
    PMID: 27873839
    Magnetic nanoparticles of Fe₃O₄ were synthesized and characterized using transmission electron microscopy and X-ray diffraction. The Fe₃O₄ nanoparticles were found to have an average diameter of 5.48 ±1.37 nm. An electrochemical biosensor based on immobilized alkaline phosphatase (ALP) and Fe₃O₄ nanoparticles was studied. The amperometric biosensor was based on the reaction of ALP with the substrate ascorbic acid 2-phosphate (AA2P). The incorporation of the Fe₃O₄ nanoparticles together with ALP into a sol gel/chitosan biosensor membrane has led to the enhancement of the biosensor response, with an improved linear response range to the substrate AA2P (5-120 μM) and increased sensitivity. Using the inhibition property of the ALP, the biosensor was applied to the determination of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). The use of Fe₃O₄ nanoparticles gives a two-fold improvement in the sensitivity towards 2,4-D, with a linear response range of 0.5-30 μgL-1. Exposure of the biosensor to other toxicants such as heavy metals demonstrated only slight interference from metals such as Hg2+, Cu2+, Ag2+ and Pb2+. The biosensor was shown to be useful for the determination of the herbicide 2, 4-D because good recovery of 95-100 percent was obtained, even though the analysis was performed in water samples with a complex matrix. Furthermore, the results from the analysis of 2,4-D in water samples using the biosensor correlated well with a HPLC method.
  12. Sharina AH, Lee YH, Musa A
    Sensors (Basel), 2008 Oct 16;8(10):6407-6416.
    PMID: 27873876
    The role of incorporation of gold nanoparticles (50-130 nm in diameter) into a series of photocurable methacrylic-acrylic based biosensor membranes containing tyrosinase on the response for phenol detection was investigated. Membranes with different hydrophilicities were prepared from 2-hydroxyethyl methacrylate and n-butyl acrylate via direct photocuring. A range of gold nanoparticles concentrations from 0.01 to 0.5 % (w/w) was incorporated into these membranes during the photocuring process. The addition of gold nanoparticles to the biosensor membrane led to improvement in the response time by a reduction of approximately 5 folds to give response times of 5-10 s. The linear response range of the phenol biosensor was also extended from 24 to 90 mM of phenol. The hydrophilicities of the membrane matrices demonstrated strong influence on the biosensor response and appeared to control the effect of the gold nanoparticles. For less hydrophilic methacrylic-acrylic membranes, the addition of gold nanoparticles led to a poorer sensitivity and detection limit of the biosensor towards phenol. Therefore, for the application of gold nanoparticles in the enhancement of a phenol biosensor response, the nanoparticles should be immobilized in a hydrophilic matrix rather than a hydrophobic material.
  13. Tan LL, Musa Ahmad
    Analisis kuantitatif telah dilakukan untuk menentukan kepekatan ion aluminium (Al3+) dalam larutan dengan menggunakan kaedah spektrofotometri UL-Nampak dan jaringan neural tiruan (ANN). Reagen morin telah digunakan untuk membentuk kompleks morin-Al(III). Pencirian terhadap reagen dalam larutan termasuk analisis kestabilan foto reagen, kesan pH, kesan kepekatan, masa rangsangan, julat kepekatan dinamik dan kebolehulangan telah dilakukan. Penggunaan ANN telah berupaya memanjangkan julat kepekatan dinamik ion Al3+ sehingga julat kepekatan 1-13 ppm.
  14. Nurul Huda Abd. Karim, Musa Ahmad, Mohammad Osman, Herman, Ahmad Mahir Mokhtar
    Kajian ini menilai potensi ekstrak pewarna kaliks Hibiscus Sabdariffa L. (rosel) sebagai bahan sensor. Dalam kajian ini, sensor pH dibangunkan menggunakan ekstrak warna kemerahan semulajadi dalam kelopak rosel, delfinidin-3-sambubiosida yang dipegunkan dalam kertas turas gentian kaca. Dalam larutan bebas, ekstrak rosel dicirikan menggunakan spektrofotometer UL-nampak untuk mengkaji kesan pH, kepekatan ekstrak, masa ransangan keadaan mantap, analisis kebolehulangan dan analisis kestabilan foto. Ekstrak rosel terpegun dicirikan dengan menggunakan spektrofotometer pantulan untuk mengkaji kesan pH, masa ransangan keadaan mantap, analisis kebolehulangan, analisis kestabilan foto dan kajian histerisis. Hasil kajian menunjukkan bahawa ekstrak bahan semulajadi boleh digunakan sebagai bahan sensor dalam pembinaan sensor optik pH.
  15. Norlaili Abu Bakar, Musa Ahmad, Rusli Daik
    Sains Malaysiana, 2008;37:233-237.
    Molecularly imprinted polymer (MIP) based on acrylate monomer was prepared at 80°C for 5 hours using p-xylene and ethylene glycol dimethacrylate (EGDMA) as a template and crosslinking agent respectively. The polymer obtained was washed with a mixture of acetic acid and methanol (1:4) and dried in the vacuum oven at 80°C. FTIR spectrum showed that all the templates were leached out from polymer during excessive washing and drying stage. The rebinding test result showed that the MIP was bonded with the analyte in the presence of organic solvents as shown by FTIR spectroscopy. The SEM micrograph showed that non-imprinted polymer (NIP) had no cavity as compared to MIP.
  16. Rosmawani Mohammad, Musa Ahmad, Jamaluddin Mohd Daud
    Sensor optik pH berasaskan reagen kurkumin terpegun dalam matriks hibrid sol-gel/kitosan melamin telah dibangunkan dalam kajian ini. Sensor optik pH ini memberikan rangsangan linear pada julat pH 9-13 (R2 = 0.9846). Seterusnya, nilai RSD kebolehulangan adalah 7.38% - 9.65%, manakala nilai RSD kebolehasilan pula adalah 2.18% - 4.72%. Kestabilanfoto yang baik bagi reagen kurkumin terpegun diperolehi apabila filem disimpan dalam persekitaran gelap dengan nilai RSD 3.69% untuk tempoh kajian 3 minggu. Tiada kesan histerisis diperhatikan apabila sensor digunakan untuk mengukur pH dalam kitaran pH 2-12-2. Masa rangsangan sensor adalah 10-20 saat. Penentuan nilai pH bagi beberapa sampel sebenar menggunakan sensor pH yang dihasilkan dalam kajian ini menunjukkan tiada perbezaan secara signifikan pada nilai pH yang diperolehi apabila dibandingkan dengan keputusan yang diperolehi menggunakan meter pH.
  17. Tan LL, Musa A, Lee YH
    Sensors (Basel), 2011;11(10):9344-60.
    PMID: 22163699 DOI: 10.3390/s111009344
    The use of the enzyme alanine dehydrogenase (AlaDH) for the determination of ammonium ion (NH(4)(+)) usually requires the addition of pyruvate substrate and reduced nicotinamide adenine dinucleotide (NADH) simultaneously to effect the reaction. This addition of reagents is inconvenient when an enzyme biosensor based on AlaDH is used. To resolve the problem, a novel reagentless amperometric biosensor using a stacked methacrylic membrane system coated onto a screen-printed carbon paste electrode (SPE) for NH(4)(+) ion determination is described. A mixture of pyruvate and NADH was immobilized in low molecular weight poly(2-hydroxyethyl methacrylate) (pHEMA) membrane, which was then deposited over a photocured pHEMA membrane (photoHEMA) containing alanine dehydrogenase (AlaDH) enzyme. Due to the enzymatic reaction of AlaDH and the pyruvate substrate, NH(4)(+) was consumed in the process and thus the signal from the electrocatalytic oxidation of NADH at an applied potential of +0.55 V was proportional to the NH(4)(+) ion concentration under optimal conditions. The stacked methacrylate membranes responded rapidly and linearly to changes in NH(4)(+) ion concentrations between 10-100 mM, with a detection limit of 0.18 mM NH(4)(+) ion. The reproducibility of the amperometrical NH(4)(+) biosensor yielded low relative standard deviations between 1.4-4.9%. The stacked membrane biosensor has been successfully applied to the determination of NH(4)(+) ion in spiked river water samples without pretreatment. A good correlation was found between the analytical results for NH(4)(+) obtained from the biosensor and the Nessler spectrophotometric method.
  18. Nur Ellina Azmi, Jaafar Abdullah, Musa Ahmad, Lee YH, Hamidah Sidek, Samsulida Abd Rahman
    Sains Malaysiana, 2011;40:1263-1269.
    Bioanalisis bagi pengesanan ammonium berdasarkan penggunaan sistem dua enzim Glutamat dehidrogenase-Diaporase (GLDH-Dph) dan reagen tiazolil biru tetrazolium bromida (MTT) diterangkan. Dalam kajian ini, GLDH memangkinkan tindak balas penukaran asid α-ketoglutarik membentuk L-glutamat dan kofaktor β-nikotinamida adenina dinukleotida (NADH) akan dioksidakan kepada NAD+ dengan kehadiran ammonium. Seterusnya, baki NADH yang tidak digunakan dioksidakan kepada NAD+ oleh Dph dan MTT dan diturunkan kepada formazan yang berwarna ungu. Keamatan formazan yang terbentuk dicerap menggunakan spektrofotometer pada panjang gelombang 563 nm. Bioanalisis ini memberikan rangsangan yang optimum bagi pengesanan ammonium pada pH larutan penimbal fosfat bersamaan 8, kepekatan GLDH, Dph dan reagen MTT pada 13.2 unit/mL, 1.17 unit/mL dan 0.2 mM, masing-masing. Bioanalisis ini memberikan rangsangan linear terhadap ammonium dalam julat kepekatan 3 - 50 μM dengan had pengesanan 1 μM.
  19. Tan LL, Musa Ahmad, Lee YH
    Sains Malaysiana, 2011;40:1105-1113.
    A quantitative analysis has been conducted to determine the concentration of ammonium (NH4+) ion in solution by using Ultraviolet-visible spectrophotometry method and artificial neural network (ANN). Riegler’s reagent was used to form Riegler-NH4+ complex. The characterisations of Riegler’s reagent in solution such as photostability, pH effect, reagent concentration, dynamic range and reproducibility were conducted. The colour change of the Riegler’s reagent after reaction with NH4+ was yellow to red. The Riegler’s reagent responds linearly to NH4+ ion concentration in the range of 1-7 ppm with optimum response at pH7. Satisfactory reproducibility (2.0-2.8%) were obtained with this reagent. The effect of interfering ions that may contain in the leachate on the determination of NH4+ ion was also studied. The application of ANN enabled the extension of the useful dynamic concentration range of NH4+ ion to 1–24 ppm. The best ANN architecture for Riegler-NH4+ complex was built from 29 hidden neurons, 21,389 epochs number and 0.001% learning rate which produced sum square error (SSE) value of 0.0483 with an average calibration error of 1.4136.
  20. Musa AS
    J Transcult Nurs, 2016 Mar;27(2):117-25.
    PMID: 24867886 DOI: 10.1177/1043659614537305
    This study reported the differences in factor structure of the Spiritual Well-Being Scale (SWBS) among Jordanian Arab and Malaysian Muslim participants and further examined its validity and reliability. A convenience sample of 553 Jordanian Arab and 183 Malaysian Malay Muslim university students was recruited from governmental universities in northern Jordan. The findings of this study revealed that this scale consists of two factors for the Jordanian Arab group, representing the "Religious Well-Being" and the "Existential Well-Being" subscales, and consists of three factors for the Malaysian group, representing the "Affiliation/Meaning and Purpose," "Positive Existential Well-Being/God Caring and Love," and "Alienation/Despair" subscales. In conclusion, the factor structure of the SWBS for both groups in this study was psychometrically sound with evidence of acceptable to good validity and reliability. Furthermore, this study supported the multidimensional nature of the SWBS and the earlier notion that ethnicity shapes responses to this scale.
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links