Displaying publications 21 - 40 of 85 in total

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  1. Superior photoelectrocatalytic performance of ternary structural BiVO4/GQD/g-C3N4 heterojunction
    Samsudin MFR, Ullah H, Tahir AA, Li X, Ng YH, Sufian S
    J Colloid Interface Sci, 2021 Mar 15;586:785-796.
    PMID: 33198982 DOI: 10.1016/j.jcis.2020.11.003
    Herein, we performed an encyclopedic analysis on the photoelectrocatalytic hydrogen production of BiVO4/g-C3N4 decorated with reduced graphene oxide (RGO) or graphene quantum dots (GQDs). The differences between RGO and GQDs as an electron mediator was revealed for the first time in the perspective of theoretical DFT analysis and experimental validation. It was found that the incorporation of GQDs as an electron mediator promotes better photoelectrocatalytic hydrogen performance in comparison to the RGO. The addition of GQD can significantly improve the activity by 25.2 and 75.7% in comparison to the BiVO4/RGO/g-C3N4 and binary composite samples, respectively. Correspondingly, the BiVO4/GQD/g-C3N4 attained the highest photocurrent density of 19.2 mA/cm2 with an ABPE of 0.57% without the presence of any sacrificial reagents. This enhancement is stemming from the low photocharge carrier transfer resistance which was further verified via DFT study. The DFT analysis revealed that the BiVO4/GQD/g-C3N4 sample shared their electronic cloud density through orbital hybridization while the BiVO4/RGO/g-C3N4 sample show less mutual sharing. Additionally, the charge redistribution of the GQDs-composite at the heterostructure interface articulates a more stable and stronger heterojunction than the RGO-composite. Notably, this study provides new insights on the effect of different carbonaceous materials (RGO and GQDs) which are often used as an electron mediator to enhance photocatalytic activity.
    Matched MeSH terms: Indicators and Reagents
  2. Azostix: a rapid test for blood urea
    Buttery JE, de Witt GF, Ahmad UO
    Med J Malaya, 1969 Jun;23(4):265-8.
    PMID: 4242173
    Matched MeSH terms: Indicators and Reagents
  3. Fulltext Preliminary forensic assessment of the visualised fingerprints on nonporous substrates immersed in water using the green and optimised novel nanobio-based reagent
    Azman AR, Mahat NA, Abdul Wahab R, Ahmad WA, Ismail D
    Sci Rep, 2022 08 30;12(1):14780.
    PMID: 36042359 DOI: 10.1038/s41598-022-18929-8
    The discovery of forensic evidence (e.g. weapons) during forensic underwater investigations has seen an increasing trend. To date, small particle reagent (SPR) has been one of the routinely used methods for visualising fingerprints on wet, non-porous substrates. However, the long term use of SPR is detrimental to humans and environment due to the use of toxic chemicals. Although previously we have successfully developed and optimised a greener nanobio-based reagent (NBR), its suitable practical use in a more realistic scene (e.g. outdoor pond) was not evaluated. Therefore, this present research is aimed at (1) investigating the performance of NBR against the benchmark SPR in visualising fingerprints immersed in a natural outdoor pond and (2) evaluating the greenness of NBR against the analytical Eco-Scale. Results showed that the performance of the optimised NBR was mostly comparable (University of Canberra (UC) comparative scale: 0) with SPR at visualising fingerprints on three different non-porous substrates immersed in a natural outdoor pond. Observably, the NBR had higher preference towards aged fingerprints (up to 4 weeks of immersion). In addition, its greenness assessment revealed 76 points, indicating 'excellent green analysis'. The findings gathered here further supported the practical use of the NBR in forensic investigations.
    Matched MeSH terms: Indicators and Reagents
  4. Comparative study of various pretreatment reagents on rice husk and structural changes assessment of the optimized pretreated rice husk
    Ang TN, Ngoh GC, Chua AS
    Bioresour Technol, 2013 May;135:116-9.
    PMID: 23138072 DOI: 10.1016/j.biortech.2012.09.045
    The performance of alkalis (NaOH and Ca(OH)2) and acids (H2SO4, HCl, H3PO4, CH3COOH, and HNO3) in the pretreatment of rice husk was screened, and a suitable reagent was assessed for subsequent optimization using response surface methodology. From the assessment, HCl that hydrolysed rice husk well was optimized with three parameters (HCl loading, pretreatment duration, and temperature) using Box-Behnken Design. The optimized condition (0.5% (w/v) HCl loading, 125 °C, 1.5 h) is relatively mild, and resulted in ~22.3mg TRS/ml hydrolysate. The reduced model developed has good predictability, where the predicted and experimental results differ by only 2%. The comprehensive structural characterization studies that involved FT-IR, XRD, SEM, and BET surface area determination showed that the pretreated rice husk consisted mainly of cellulose and lignin. Compared to untreated rice husk, pretreated rice husk possessed increased pore size and pore volume, which are expected to be beneficial for fungal growth during fermentation.
    Matched MeSH terms: Indicators and Reagents/pharmacology
  5. Electrochemical-assisted photodegradation of dye on TiO2 thin films: investigation on the effect of operational parameters
    Zainal Z, Lee CY, Hussein MZ, Kassim A, Yusof NA
    J Hazard Mater, 2005 Feb 14;118(1-3):197-203.
    PMID: 15721544
    Electrochemical-assisted photodegradation of methyl orange has been investigated using TiO2 thin films. The films were prepared by sol-gel dip-coating method. Several operational parameters to achieve optimum efficiency of this electrochemical-assisted photodegradation system have been tested. Photoelectrochemical degradation was studied using different light sources and light intensity. The light sources chosen ranged from ultraviolet to visible light. The effect of agitation of the solution at different speeds has also been studied. Slight improvement of photodegradation rate was observed by applying higher agitation speed. Investigation on the electrode after repeated usages show the electrode can be reused up to 20 times with percentage of deficiency less than 15%. The study on the effect of solution temperature indicated that the activation energy of the methyl orange degradation is 18.63 kJ mol(-1).
    Matched MeSH terms: Indicators and Reagents/chemistry*
  6. Estimation of uncertainty from method validation data: Application to a reverse-phase high-performance liquid chromatography method for the determination of amino acids in gelatin using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate reagent
    Azilawati MI, Dzulkifly MH, Jamilah B, Shuhaimi M, Amin I
    J Pharm Biomed Anal, 2016 Sep 10;129:389-397.
    PMID: 27454091 DOI: 10.1016/j.jpba.2016.07.012
    A detailed procedure for estimating uncertainty according to the Laboratory of Government Chemists/Valid Analytical Measurement (LGC/VAM) protocol for determination of 18 amino acids in gelatin is proposed. The expanded uncertainty was estimated using mainly the method validation data (precision and trueness). Other sources of uncertainties were contributed by components in standard preparation measurements. The method scope covered a single matrix (gelatin) under a wide range of analyte concentrations. The uncertainty of method precision, μ(P) was 0.0237-0.1128pmolμl(-1) in which hydroxyproline and histidine represented the lowest and highest values of uncertainties, respectively. Proline and phenylalanine represented the lowest and highest uncertainties value for method recovery, μ(R) that was estimated within 0.0064-0.0995pmolμl(-1). The uncertainties from other sources, μ(Std) were 0.0325, 0.0428 and 0.0413pmolμl(-1) that were contributed by hydroxyproline, other amino acids and cystine, respectively. Hydroxyproline and phenylalanine represented the lowest and highest values of expanded uncertainty, U(y) that were determined at 0.0949 and 0.2473pmolμl(-1), respectively. The data were accurately defined and fulfill the technical requirements of ISO 17025:2005.
    Matched MeSH terms: Indicators and Reagents/chemistry
  7. Fulltext Differentiation of dental pulp stem cells into neuron-like cells in serum-free medium
    Zainal Ariffin SH, Kermani S, Zainol Abidin IZ, Megat Abdul Wahab R, Yamamoto Z, Senafi S, et al.
    Stem Cells Int, 2013;2013:250740.
    PMID: 24348580 DOI: 10.1155/2013/250740
    Dental pulp tissue contains dental pulp stem cells (DPSCs). Dental pulp cells (also known as dental pulp-derived mesenchymal stem cells) are capable of differentiating into multilineage cells including neuron-like cells. The aim of this study was to examine the capability of DPSCs to differentiate into neuron-like cells without using any reagents or growth factors. DPSCs were isolated from teeth extracted from 6- to 8-week-old mice and maintained in complete medium. The cells from the fourth passage were induced to differentiate by culturing in medium without serum or growth factors. RT-PCR molecular analysis showed characteristics of Cd146(+) , Cd166(+) , and Cd31(-) in DPSCs, indicating that these cells are mesenchymal stem cells rather than hematopoietic stem cells. After 5 days of neuronal differentiation, the cells showed neuron-like morphological changes and expressed MAP2 protein. The activation of Nestin was observed at low level prior to differentiation and increased after 5 days of culture in differentiation medium, whereas Tub3 was activated only after 5 days of neuronal differentiation. The proliferation of the differentiated cells decreased in comparison to that of the control cells. Dental pulp stem cells are induced to differentiate into neuron-like cells when cultured in serum- and growth factor-free medium.
    Matched MeSH terms: Indicators and Reagents
  8. Comparison of signal-to-noise, blank determination, and linear regression methods for the estimation of detection and quantification limits for volatile organic compounds by gas chromatography
    Sanagi MM, Ling SL, Nasir Z, Hermawan D, Ibrahim WA, Abu Naim A
    J AOAC Int, 2010 2 20;92(6):1833-8.
    PMID: 20166602
    LOD and LOQ are two important performance characteristics in method validation. This work compares three methods based on the International Conference on Harmonization and EURACHEM guidelines, namely, signal-to-noise, blank determination, and linear regression, to estimate the LOD and LOQ for volatile organic compounds (VOCs) by experimental methodology using GC. Five VOCs, toluene, ethylbenzene, isopropylbenzene, n-propylbenzene, and styrene, were chosen for the experimental study. The results indicated that the estimated LODs and LOQs were not equivalent and could vary by a factor of 5 to 6 for the different methods. It is, therefore, essential to have a clearly described procedure for estimating the LOD and LOQ during method validation to allow interlaboratory comparisons.
    Matched MeSH terms: Indicators and Reagents
  9. On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces
    Yin SH, Kuppuswamy R
    Forensic Sci Int, 2009 Jan 10;183(1-3):50-3.
    PMID: 19041202 DOI: 10.1016/j.forsciint.2008.10.009
    Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces, has been practised quite successfully in forensic science laboratories all over the world. A large number of etchants suitable for particular metal surfaces based on empirical studies is available in the literature. This article reviews the sensitivity and efficacy of some popular etchants for recovering obliterated marks on medium carbon steel (0.31% C with ferrite-pearlite microstructure) used in automobile parts. The experiments involved engraving these carbon steel plates with some alphanumeric characters using a computer controlled machine "Gravograph" and erasing them to several depths below the bottom of their engraving depth. Seven metallographic reagents of which most of them were copper containing compounds were chosen for etching. The erased plates were etched with every one of these etchants using swabbing method. The results have revealed that Fry's reagent comprising cupric chloride 90 g, hydrochloric acid 120 mL and water 100mL provided the necessary contrast and was concluded to be the most sensitive. The same reagent was recommended by earlier workers for revealing strain lines in steel surfaces. Earlier, another reagent containing 5 g copper sulphate, 60 mL water, 30 mL (conc.) ammonium hydroxide, and 60 mL (conc.) hydrochloric acid was proved to be more sensitive to restore erased marks on low carbon steel (0.1% C with ferrite-pearlite structure) [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27-32]. Thus the sensitivity of the etching reagent on steel surfaces appeared to be dependent on the content of carbon in the steel.
    Matched MeSH terms: Indicators and Reagents
  10. Bromophenol blue binding as a probe to study urea and guanidine hydrochloride denaturation of bovine serum albumin
    Halim AA, Kadir HA, Tayyab S
    J. Biochem., 2008 Jul;144(1):33-8.
    PMID: 18344543 DOI: 10.1093/jb/mvn036
    Urea and guanidine hydrochloride (GdnHCl) denaturation of bovine serum albumin (BSA) were investigated using bromophenol blue (BPB) binding as a probe. Addition of BPB to BSA produced an absorption difference spectrum in the wavelength range, 525-675 nm with a minimum at 587 nm and a maximum at 619 nm. The magnitude of absorption difference (DeltaAbs.) at 619 nm decreased on increasing urea/GdnHCl concentration and followed the denaturation curve. The denaturation was found to be a two-state, single-step transition. The transitions started at 1.75 and 0.875 M and completed at 6.5 and 3.25 M with the mid point occurring around 4.0 and 1.5 M urea and GdnHCl concentrations, respectively. The value of free energy of stabilization, DeltaGDH2O as determined from urea and GdnHCl denaturation curves was found to be 4041 and 4602 cal/mol, respectively. Taken together, these results suggest that BPB binding can be used as a probe to study urea and GdnHCl denaturation of BSA.
    Matched MeSH terms: Indicators and Reagents
  11. Restoration of engraved marks on steel surfaces by etching technique
    Zaili MA, Kuppuswamy R, Harun H
    Forensic Sci Int, 2007 Aug 24;171(1):27-32.
    PMID: 17088038
    It is known that restoration of erased engraved identification marks on the engine and the chassis of a car or on a firearm has low success rate. Unlike stamping, engraving on a metal surface leaves no pronounced, permanent subsurface deformation in the crystalline structure, also called dislocation that can be revealed by suitable methods. Hence, the current research work investigated whether metallographic reagents used in the restoration of stamp (compression) marks could be applied to recover engraved marks on steel surfaces and also to establish the sensitivity and effectiveness of some of these reagents for the restoration of the marks. Experiments were conducted by mechanically engraving alphanumeric characters on several steel plates using a computer controlled engraving machine called Gravograph. The markings were later erased from the above steel plates by removing the metal in stages of 0.01 mm through 0.04 mm below the bottom of the engraving. Several plates were thus prepared wherein each one had been abraded to a specific depth. Then eight metallographic reagents were tested on each one of the above erased plates using a swabbing technique. The results had shown that while most of the reagents were able to restore marks up to certain levels of erasure, the reagent 5 g copper sulphate, 60 ml water, 30 ml concentrated ammonium hydroxide and 60 ml concentrated hydrochloric acid restored marks erased to a depth of 0.04 mm below the engraving depth, thus presenting itself the most sensitive reagent. Quite significantly, the above reagent was also able to decipher successfully the original engraved marks that had been erased and engraved with a new number, or obliterated by centre punching. The results of this research work should benefit the forensic practitioners engaged in the serial number recovery on vehicles, firearms and other objects.
    Matched MeSH terms: Indicators and Reagents
  12. Application of the artificial neural network in quantitative structure-gradient elution retention relationship of phenylthiocarbamyl amino acids derivatives
    Tham SY, Agatonovic-Kustrin S
    J Pharm Biomed Anal, 2002 May 15;28(3-4):581-90.
    PMID: 12008137
    Quantitative structure-retention relationship(QSRR) method was used to model reversed-phase high-performance liquid chromatography (RP-HPLC) separation of 18 selected amino acids. Retention data for phenylthiocarbamyl (PTC) amino acids derivatives were obtained using gradient elution on ODS column with mobile phase of varying acetonitrile, acetate buffer and containing 0.5 ml/l of triethylamine (TEA). Molecular structure of each amino acid was encoded with 36 calculated molecular descriptors. The correlation between the molecular descriptors and the retention time of the compounds in the calibration set was established using the genetic neural network method. A genetic algorithm (GA) was used to select important molecular descriptors and supervised artificial neural network (ANN) was used to correlate mobile phase composition and selected descriptors with the experimentally derived retention times. Retention time values were used as the network's output and calculated molecular descriptors and mobile phase composition as the inputs. The best model with five input descriptors was chosen, and the significance of the selected descriptors for amino acid separation was examined. Results confirmed the dominant role of the organic modifier in such chromatographic systems in addition to lipophilicity (log P) and molecular size and shape (topological indices) of investigated solutes.
    Matched MeSH terms: Indicators and Reagents
  13. Comparison of solvent extraction and solid-phase extraction for the determination of organochlorine pesticide residues in water
    Tan GH
    Analyst, 1992 Jul;117(7):1129-32.
    PMID: 1524230
    Solid-phase extraction (SPE) of organochlorine pesticide residues from environmental water samples was evaluated using octadecyl (C18)-bonded porous silica. The efficiency of SPE of these pesticide residues from reagent water samples at 1-5 micrograms dm-3 levels was compared with those obtained by solvent extraction with hexane and Freon TF (trichlorotrifluoroethane). Average recoveries exceeding 80% for these organochlorine pesticides were obtained via the SPE method using small cartridges containing 100 mg of 40 microns C18-bonded porous silica. The average recovery by solvent extraction with hexane and Freon TF exceeded 90% in both instances. It was concluded that the recoveries and precision for the SPE of organochlorine pesticides were poorer than those for the solvent extraction method. Organochlorine pesticide residue levels in environmental water samples from two major rivers flowing through predominantly rice-growing areas were monitored by gas chromatography using the solvent extraction method with hexane. Exceptionally high levels of organochlorine pesticide residues such as BHC, DDT, heptachlor, endosulfan and dieldrin were found in these water samples.
    Matched MeSH terms: Indicators and Reagents
  14. Synthesis and characterization of potential tumor scintigraphic agents
    Awaluddin AB, Jacobs JJ, Bourne DW, Maddalena DJ, Wilson JG, Boyd RE
    Int J Rad Appl Instrum A, 1987;38(8):671-4.
    PMID: 2822626
    Potential tumor imaging radiopharmaceutical agents have been prepared by attaching a cisplatin derivative to a ligand capable of forming a stable complex with 99mTc. Three new organometallic compounds, with iminodiacetic acid as the 99mTc chelating group and 2,3-diaminopropionamide as the platinum complexing group, have been prepared and characterized. Preliminary biodistribution studies in tumor bearing mice support the utility of this approach.
    Matched MeSH terms: Indicators and Reagents
  15. Fulltext Phytochemical screening and enzymatic and antioxidant activities of Erythrina suberosa (Roxb) bark
    Ahmed Z, Aziz S, Hanif M, Mohiuddin SG, Ali Khan SH, Ahmed R, et al.
    J Pharm Bioallied Sci, 2020 04 10;12(2):192-200.
    PMID: 32742119 DOI: 10.4103/jpbs.JPBS_222_19
    Background: This study aimed to evaluate the phytochemicals screening of Erythrina suberosa (Roxb) bark and to analyze the enzymatic activities of its various organic fractions.

    Materials and Methods: Crude methanolic fraction of E. suberosa (Roxb) bark and its respective fractions were screened for the presence of different phytochemicals with different reagents. On the basis of increasing order of polarity, different organic solvents were used to obtain different fractions. Enzymatic studies were performed on crude methanolic extract of the plant. All the assays were performed under standard in vitro conditions.

    Results: The phytochemical analysis shows the presence of alkaloids, phenols, triterpenoids, phytosterols, and flavonoids. Phenolic compounds and flavonoids are the major constituents of the plant. In anticholinesterase assay, the percent inhibition of standard drug (eserine) was 91.27 ± 1.17 and the half maximal inhibitory concentration (IC50) was 0.04 ± 0.0001. For α-glucosidase inhibition, the IC50 value for Dichloromethane fraction was 8.45 ± 0.13, for Methanol fraction it was 64.24 ± 0.15, and for aqueous fraction it was 42.62 ± 0.17 as compared with standard IC50 that is 37.42 (acarbose). Furthermore, results show that all fractions have potential against anti-urease enzyme, but DCM fraction of crude aqueous extract has significant IC50 value (45.26 ± 0.13) than other fractions.

    Conclusion: Keeping in view all the results, it is evident that the plant can be used in future for formulating effective drugs against many ailments. Secondary metabolites and their derivatives possess different biological activities, for example, .g. flavonoids in cancer, asthma, and Alzheimer. Furthermore, the extracts of this plant can be used in their crude form, which is an addition to the complementary and alternative treatment strategies.

    Matched MeSH terms: Indicators and Reagents
  16. Fulltext Arene diazonium saccharin intermediates: a greener and cost-effective alternative method for the preparation of aryl iodide
    Zaharani L, Ghaffari Khaligh N, Shahnavaz Z, Rafie Johan M
    Turk J Chem, 2020;44(3):535-542.
    PMID: 33488175 DOI: 10.3906/kim-2002-26
    In the current protocol, the arene diazonium saccharin derivatives were initially produced from various substituted aromatic amines; subsequently, these intermediates were treated with a greener organic iodide for the preparation of the aryl iodide. We tried to choose low-cost, commercially available, biodegradable, recoverable, ecofriendly, and safe reagents and solvents. The arene diazonium saccharin intermediates could be stored in the liquid phase into a refrigerator for a long time with no significant loss activity. The outstanding merits of the current protocol (a) included the partial recovering of saccharin and tetraethylammonium salt, (b) reduce the use of solvents and the reaction steps due to eliminating separation and purification of intermediates, (c) good yield of the sterically hindered substrates, and (d) avoid the generation of heavy metal or corrosive waste.
    Matched MeSH terms: Indicators and Reagents
  17. Fulltext DETERMINATION OF REACTIVE BLACK 5 (RB5) BY DIFFERENTIAL PULSE ANODIC STRIPPING VOLTAMMETRIC TECHNIQUE
    Nur Syamimi Zainudin, Nur Aqilah Abdul Rahman
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2021;9(1):73-79.
    MyJurnal
    Dyes are aromatic organic compound which have an affinity towards the substrate to which they are being applied to. The presence of dyes in wastewater samples is not safe for human even at low level. The presence of dyes in wastewater which are discharged from textile industry must be analysed. Hence, a precise, fast, accurate, simple and inexpensive analytical method with low detection limit is needed for the determination of dyes in wastewaters. The differential pulse anodic stripping voltammetric (DPASV) technique using bare glassy carbon electrode (GCE) as a working electrode and phosphate buffer at pH 4.2 as a supporting electrolyte has been proposed for Reactive Black 5 (RB5) determination. Several experimental voltammetric parameters were being optimized for obtaining a maximum response before analytical validation of the proposed technique being carried out. The optimum parameters were initial potential (Ei) = +0.3 V, end potential (Ef) = +1.0 V, scan rate (v) = 0.04 V/s, accumulation time (tacc) = 50 s, accumulation potential (Eacc) = 0.4 V and pulse amplitude = 0.075 V. The well-defined anodic peak appeared at 0.77972 V. The response was linear from 0.5 to 1.25 mg/L (R2=0.9986) with LOD of 0.050 mg/L. The relative standard deviation (RSD) achieved were 0.08 %, 0.62 % and 0.50 %, respectively for three consecutive days. The % recovery range achieved was from 89.71 % to 111.15 %. It can be concluded that the proposed technique is precise, accurate, inexpensive, fast and has a potential to be an alternative analytical technique for RB5 analysis. The proposed method will in the future be tested for the amount of RB5 in the wastewater samples from textile industry.
    Matched MeSH terms: Indicators and Reagents
  18. Fulltext A CONVENIENT SYNTHESIS OF 5-ARYLIDENE MELDRUM'S ACID DERIVATIVES VIA KNOEVENAGEL CONDENSATION
    Adryana Izzati Adnan, noorhidayah977@uitm.edu.my, Nur Ain Nabilah Ash’ari
    Journal of Academia Universiti Teknologi MARA Negeri Sembilan, 2021;9(1):80-84.
    MyJurnal
    A series of ten 5-arylidene Meldrum’s acid derivatives had been synthesised in excellent yield via Knoevenagel condensation. This method does not require catalyst, or any further purification. Isopropylidene malonate (2,2-dimethyl-1,3-dioxane-4,6-dione), also known as Meldrum’s acid, is utilised as a core skeleton for various kind of reactions. Meldrum’s acid has features of a peculiar ring- opening sequences based on nucleophile-sensitive carbonyl functional groups at C-4 and C-6, which has made it possible for useful synthetic transformations, as well as its high acidity of methylene hydrogen at carbon position C-5. Hence, it allows the compound to be a flexible reagent for further reaction to prepare other derivatives. Therefore, Meldrum’s acid derivatives showed high potential of biological functions, such as antibacterial, antimalarial and antioxidant activities due to the olefinic linkage which played an important role in the enhancement of antimalarial activity. Furthermore, when arylidene Meldrum’s acid transformed to epoxide, the compound showed losses of antimalarial behaviour. Additionally, this compound has unique molecules due to the high acidity of methylene hydrogen at the carbon-5 position to initiate various reactions with different functional groups. In this research, Meldrum’s acid, 3 and ten its 5-arylidene derivatives (4a-e) and (5a-e) were synthesised by using two short and efficient reaction steps. The first step involved the condensation of malonic acid, 1 with acetone, 2 in acetic anhydride and acid via one-pot reaction to give Meldrum’s acid, 3 in 50% overall yield. Having Meldrum’s acid in hand, the reaction was proceeded with the Knoevenagel condensation reaction by using various functional groups, such as aryl aldehydes and aryl amines. All the synthesised compounds were characterised by using 1H and 13C spectroscopy.
    Matched MeSH terms: Indicators and Reagents
  19. Flow-through chloroquine sensor and its applications in pharmaceutical analysis
    Saad B, Zin ZM, Jab MS, Rahman IA, Saleh MI, Mahsufi S
    Anal Sci, 2005 May;21(5):521-4.
    PMID: 15913140
    Poly (vinyl chloride) membrane electrodes that responded selectively towards the antimalarial drug chloroquine are described. The electrodes were based on the use of the lipophilic potassium tetrakis(4-chlorophenyl)borate as ion-exchanger and bis(2-ethylhexyl)adipate (BEHA), or trioctylphosphate (TOP) or dioctylphenylphosphonate (DOPP) as plasticizing solvent mediator. All electrodes produced good quality characteristics such as Nernstian- and rapid responses, and are minimally interfered with by the alkali and alkaline earth metal ions tested. The membranes were next applied to a flow-through device, enabling it to function as flow-injection analysis (FIA) detector. The performance of the sensor after undergoing the FIA optimization was further evaluated for its selectivity characteristics and lifetime. Results for the determination of chloroquine in synthetic samples that contained common tablet excipients such as glucose, starch, and cellulose, and other foreign species such as cations, citric acid or lactic acid were generally satisfactory. The sensor was also successfully used for the determination of the active ingredients in mock tablets, synthetic fluids and biological fluids. The sensor was applied for the determination of active ingredients and the dissolution profile of commercial tablets was also established.
    Matched MeSH terms: Indicators and Reagents
  20. Fulltext Detection of malachite green and leuco-malachite green in fishery industry
    Hidayah, N., Abu Bakar, F., Mahyudin, N.A., Faridah, S., Nur-Azura, M.S., Zaman, M.Z.
    International Food Research Journal, 2013;20(4):1511-1519.
    MyJurnal
    This article summarises the current methods for total malachite green (MG) detection which is known as a sum of MG and leuco-malachite green (LMG) that has been used extensively in aquaculture as fungicide, dye color in textile and other purposes in food industries. LMG is a reducing form of MG, where the MG is easily reduced due to the photo-oxidative de-methylation process. Nevertheless, the use of MG had become an issue due to its toxicity effects. Many analytical instruments such as HPLC, LC—MS/MS, GC—MS, and spectrometry have been widely used for detection of MG. However, these methods require long time sample preparation and analysis, expensive, use hazardous reagents and indirect measurements. Hence, other analytical methods which are more sensitive, safe, rapid, inexpensive and portable are required. Alternatively, biosensors promise a more sensitive and rapid detection method for MG and LMG.
    Matched MeSH terms: Indicators and Reagents
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