Displaying publications 81 - 100 of 114 in total

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  1. Chen, J.X.J., Lim, P.K.C., Wong, S.F., Mak, J.W.
    Malays J Nutr, 2014;20(3):377-391.
    MyJurnal
    Introduction: Heavy metals and other contaminants in food have been a concern to food industries, consumers and governing authorities. The purpose of this study was to determine the levels of heavy metals and other elements in edible bird nests (EBNs). Methods: Raw and processed (commercial) EBNs were used in the study. Raw EBNs were collected directly from five house farms in Peninsular Malaysia - Kuala Sanglang (Kedah), Pantai Remis (Perak), Kluang Gohor), Kota Bharu (Kelantan) and Kajang (Selangor). Processed EBNs were pmchased from five Chinese traditional medicinal shops located in Peninsular Malaysia. The levels of 32 elements were determined by inductively coupled plasma-mass spectrometry and findings of the study were compared to the maximum regulatory limits set by the Standards and Industrial Research Institute of Malaysia (SIRIM) for EBNs. Results: Of the seven elements with maximum regulatory limits (As, Cd, Pb, Hg, Sn, Cu, Fe), one raw EBN was detected with mercury level of 70.180 ppb which was above the SIRIM permissible limit of 50 ppb. All the EBNs had iron levels above the SIRIM permissible limit of 30 ppb. The levels of the other 25 elements with no maximum regulatory limits (Ca, Mg, Na, K, P, Co, Cr, Mn, Mo, Se, Zn, Ag, Ba, Be, Bi, B, Li, Ni, Sb, Sr, Ti, U, V, Al, Zr) were also determined. Conclusion: The data obtained for the 25 elements with no permissible limits can serve as baseline data for further studies to establish their maximum regulatory limits.
    Matched MeSH terms: Mercury
  2. Sun, J., Jiang, Y., Amin, I., Li, Z., Prasad, K.N., Duan, X., et al.
    MyJurnal
    This research was to determine nutritional composition, essential and toxic elemental content, and major phenolic acid with antioxidant activity in Kadsura coccinea fruit. The results indicated that Kadsura coccinea fruit exhibited the high contents of total protein, total fat, ash and essential elements such as calcium (Ca), ferrum (Fe) and phosphorus (P). The levels of four common toxic elements, i.e. cadmium (Cd), mercury (Hg), arsenic (As) and lead (Pb), were lower than legal limits. By high-performance liquid chromatography (HPLC) analysis, gallic acid was identified as major phenolic acid in peel and pulp tissues. Its contents were no significant difference in both tissues. In comparison with two commercial antioxidants, the major phenolic acid extracted from Kadsura coccinea exhibited stronger 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity and reducing power. Kadsura coccinea fruit is a good source of nutrition and natural antioxidant. It is worthwhile to popularize this exotic fruit around the world.
    Matched MeSH terms: Mercury
  3. Rajan, Nithiya Shanmuga, Bhat,Rajeev, Karim, A.A.
    MyJurnal
    Unripe and ripe kundang fruits (Bouea macrophylla Griffith) is either consumed fresh or is cooked in Malaysia. In this study composition of unripe and ripe fruits (proximate, amino acids profile, minerals and heavy metal contents) were evaluated. Results obtained showed unripe kundang fruit to possess higher moisture, ash, crude lipid, crude fiber and crude protein contents than the ripe fruits. With regard to amino acid contents, unripe fruits had higher content of essential amino acids. The unripe and ripe fruits were found to be rich in essential minerals with potassium (K) to be in abundance. Heavy metals such as cadmium, nickel, mercury, lead and arsenic, were detected in trace amounts (< 5.0 mg/kg) in both unripe and ripe fruits. Through this investigation, it is concluded that both unripe and ripe fruits to posses’ adequate amount of nutritionally important compounds beneficial to human health and can be explored for commercial purposes.
    Matched MeSH terms: Mercury
  4. Lai WH, Loo SS, Rahmat N, Shaharuddin S, Daud F, Zamri Z, et al.
    MyJurnal
    Tiger’s Milk mushroom has been used for medicinal purposes by local aborigines to treat asthma, breast cancer, cough, fever and food poisoning. Molecular phylogenetic analysis utilizing RNA polymerase II, second largest subunit (RPB2) gene, identified the wild Tiger’s Milk mushrooms collected from the state of Pahang in Malaysia for this study as Lignosus rhinocerus in the order Polyporales. The tuber, stipe and pileus of this mushroom were analyzed for their basic nutritional composition (fat, protein, and carbohydrate) and toxic metal content profile (Cadmium, Lead and Mercury). The moisture content of these mushroom parts varied from 32.22% (pileus) – 46.31% (stipe). The dry matter of the mushrooms contained 2.76% (stipe) – 6.60% (pileus) proteins, 0.21% (pileus) – 0.30% (tuber) fat, 1.76% (stipe) – 4.38% (tuber) ash and 38.47% (stipe) – 56.30% (pileus) carbohydrates. The toxic metal content of the mushroom samples ranged from 0.03–0.12 mg/kg for Cd, 0.80–1.94 mg/kg for Pb and 0.05–0.10 mg/kg for Hg. The present study demonstrated that L. rhinocerus is a potential source of food due to its high carbohydrate content. In addition, the trace levels of toxic metals in this mushroom are within the safe level for consumption.
    Matched MeSH terms: Mercury
  5. Assi MA, Hezmee MN, Haron AW, Sabri MY, Rajion MA
    Vet World, 2016 Jun;9(6):660-71.
    PMID: 27397992 DOI: 10.14202/vetworld.2016.660-671
    Lead, a chemical element in the carbon group with symbol Pb (from Latin: Plumbum, meaning "the liquid silver") and has an atomic number 82 in the periodic table. It was the first element that was characterized by its kind of toxicity. In animal systems, lead (Pb) has been incriminated in a wide spectrum of toxic effects and it is considered one of the persistent ubiquitous heavy metals. Being exposed to this metal could lead to the change of testicular functions in human beings as well as in the wildlife. The lead poising is a real threat to the public health, especially in the developing countries. Accordingly, great efforts on the part of the occupational and public health have been taken to curb the dangers of this metal. Hematopoietic, renal, reproductive, and central nervous system are among the parts of the human body and systems that are vulnerable toward the dangers following exposure to high level of Pb. In this review, we discussed the massive harmful impact that leads acetate toxicity has on the animals and the worrying fact that this harmful toxicant can be found quite easily in the environment and abundance. Highlighting its (Pb) effects on various organs in the biological systems, its economic, as well as scientific importance, with the view to educate the public/professionals who work in this area. In this study, we focus on the current studies and research related to lead toxicity in animals and also to a certain extent toward human as well.
    Matched MeSH terms: Mercury
  6. Shafie, O., Sanimah, A.R.
    MyJurnal
    The status ofhve l1eavy metals: cadmium, lead copper, zinc and mercury were determined in seafood and its products imported_ti·om Thailand via Bukit Kayu Hiram, Kedah, Flame Atomic Absorption Spectrophotometer was used to determine the level of these heary metals except for mercury, where the cold vapor technique was used, Randomized sampling was done according to a predetermined sampling plan based on the previous years consignments. Data collected were compared with the maximum permitted level of -metal contaminants in fish and fish products- ofthe Fourteenth Schedule (Regulation 38) of Food Act I983 and Food Regulations I 985 to ascertain compliance. lt was noted form this study, that the level of metals detected in seafood and its products had a very wide range, The levels detected for cadmium was at a range of 0. 00] - 3.9/2, 0.07 — 0.29, 0,04 - 4,4 mg/kg in fish, shellfish and cuttlefish respectivelv. In general, cadmium level in some samples was notably higher particularly in shellfish. All samples had lead level less than the permitted value except for fish where the highest value detected was 3.28 mg/kg. The level of copper and zinc was higher than the permitted value in octopus, prawn and crab, Mercury level in all samples analvzed was found to be below the detection level. As for fish samples, zinc level was found to be higher whereas copper was within the limit. However, it was also noted that the level of all the heavy metals in jiozen jish was within the permitted limit.
    Matched MeSH terms: Mercury
  7. Lam, H.H., Ng, E.K., Ooi, A.L., Ooi, P.Y., Sellymiah, A., Siti Fareeda, A., et al.
    MyJurnal
    Objectives: To study relationship of depressive symptoms to hypertension. Methods: A cross sectional study was carried out on respondents from Kampung Awal. Hypertension was defined as self-reported or by measurement using a mercury sphymomanometer and depressive symptoms were evaluated by CES-D scale. Results: A total 103 respondents were studied. The male:female ratio was 1:1.5 with mean age of 41.8 years. Majority had formal education up to secondary school. 45% were government servant and over 95% subjects had income of RM1000 or less per each family member per month. 21.4% (n=22) self-reported to have hypertension and 7.8%(n=91) met the criteria for incident hypertension. 7.8% met the criteria for both. Mean score based on CES-D was 13.08. 32.0% subjects had depression. 54 subjects reported never experienced any strain for past 6 months and 24 reported to have 2 or more .61 subjects were overweight with mean value of BMI=26.19 kg/m2. Self-reported hypertension and incident hypertension were strongly associated with age but only selfreported hypertension was strongly associated with overweight. However, there was no significant association between hypertension with chronic strains and depressive symptoms. Conclusions: Depressive symptomatology was not associated with hypertension in this survey. Women had a significant risk in having depressive symptoms. Age =45 years & overweight were significant risks for hypertension. A prospective study will be more useful in the future to find out the association between depression and hypertension.
    Matched MeSH terms: Mercury
  8. Zaini Hamzah, Marlinda Musa, Ahmad Saat
    MyJurnal
    There are many essential and non-essential elements including metals and radionuclides present in vegetables. Howeve r, the accumulation of the several metals and radionuclides might cause the contamination to vegetables itself. Green m ustard (Brasissca rapa var. Parachinesis L.) was selected to represent the vegetable in this study. Objectives of this stud y are to determine the concentration of metals and radionuclides in the samples and to calculate the enrichment factor ( EF) and also to estimate the uptake, base on biological accumulation coefficient (BAC), for the various parts of selecte d vegetables. Three farmlands in the Cameron Highlands were studied namely Bharat, Kg Raja and Bertam area. The g reen mustard and soil samples were collected during the harvest season. Samples were dried, ground and sieved prior t o analysis. Analyses for both samples were done by using X-rays Fluorescence Spectroscopy (XRF) to measure the conc entration of Fe, Zn, Hg, U and Th. The concentration of all elements in the soils is lower than their concentration in the control soil, except for Zn, U and Th. The concentration of all elements in Green Mustard is lower than their concentrat ion in the soil where it was grown. The EF values in the Brasissca rapa var. Parachinesis L are lower than 2 except for U and Th, indicating some degree of contamination due to anthropogenic activities or naturally origin. The BAC values show that Zn and Hg were accumulated in the green mustard, depending on where the plant grows.
    Matched MeSH terms: Mercury
  9. Quek MC, Chin NL, Yusof YA, Law CL, Tan SW
    Food Res Int, 2018 07;109:35-43.
    PMID: 29803459 DOI: 10.1016/j.foodres.2018.03.078
    Edible bird's nest (EBN) is a precious food made from the solidified saliva of swiftlets. EBN from three types of origin, namely production, swiftlet species and geographical were characterised based on its nutritional composition, physicochemical properties and antioxidant properties. Proximate composition, total phenolic content (TPC) and antioxidant activities were determined following official methods, while mineral and heavy metal contents were obtained by respective atomic adsorption spectrometry (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS). Amino acids profile and sialic acid were determined using high performance liquid chromatography (HPLC). Calcium and sodium were the major elements in EBN samples at averages of 17,267 mg/kg and 13,681 mg/kg, respectively. Despite protein contents were not significantly different; interestingly the total amino acids in A. fuciphagus EBN, 64.57 g/100 g was found to be 23% higher than in A. maximus EBN. EBN from house, A. fuciphagus and Peninsular Malaysia had greater antioxidant activities, 2.33-3.49 mg AAE/g and higher sialic acid, 13.57 g/100 g while those from cave, A. maximus and East Malaysia contained more minerals like calcium and magnesium. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric ion reducing antioxidant power (FRAP) of house, A. fuciphagus and Peninsular Malaysia EBNs were approximately 2 times greater than the others. All samples were complied with the Malaysian Standard MS 2334:2011, except for mercury and nitrite. The overall findings suggest that the quality of EBN was varied following the production, species and geographical origins.
    Matched MeSH terms: Mercury
  10. Othman, A.R., Rahman, M.F., Shukor, M.Y., Abu Zeid, I.M., Ariffin, F.
    MyJurnal
    Chemical toxins and organic contaminants such as hydrocarbons and dyes are major global
    contaminants with countless tones of those chemicals are created yearly with a significant
    amount release to the environment. In this work we screen the ability of a molybdenum-reducing
    bacterium isolated from contaminated soil to decolorize various azo and triphenyl methane dyes
    independent of molybdenum reduction. Biochemical analysis resulted in a tentative identification
    of the bacterium as Enterobacter sp. strain Zeid-6. The bacterium was able to decolorize the azo
    dye Orange G. The bacterium reduces molybdate to Mo-blue optimally at pH between 5.5 and
    8.0 and temperatures of between 30 and 37 oC. Other requirements include a phosphate
    concentration of 5 mM and a molybdate concentration of 20 mM. The absorption spectrum of the
    Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a
    reduced phosphomolybdate. Molybdenum reduction was inhibited by copper, lead, mercury and
    silver which showed 36.8, 16.9, 64.9 and 67.6% inhibition to Mo-reducing activity of
    Enterobacter sp. strain Zeid-6, respectively. The resultant molybdenum blue spectrum closely
    resembles the spectrum of molybdenum blue from the phosphate determination method. The
    ability of this bacterium to detoxify molybdenum and decolorize azo dye makes this bacterium
    an important tool for bioremediation.
    Matched MeSH terms: Mercury
  11. Abo-Shakeer, L.K.A., Rahman, M.F.A., Yakasai, H., Syed, M.A., Shukor M.Y., Bakar, N.A., et al.
    MyJurnal
    Bacterial based remediation of environmental toxicants is a promising innovative technology
    for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
    from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
    It is important that the constants from newer enzyme sources be characterized so that a
    comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
    previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
    activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
    NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
    mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
    pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
    cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
    with copper being the most potent with an almost complete inhibition of enzyme activity
    observed.
    Matched MeSH terms: Mercury
  12. Tengku Nur Alia TKA, Hing LS, Sim SF, Pradit S, Ahmad A, Ong MC
    Mar Pollut Bull, 2020 Apr;153:111009.
    PMID: 32275555 DOI: 10.1016/j.marpolbul.2020.111009
    Metallic contamination in seafood, especially fish, has been of increasing concern to human health. Moreover, with increasing dependency on farmed fish for fish resources, the metallic contamination in them is still questionable. This study aimed to investigate the effects of cooking (steaming) on heavy metal concentration in farmed fish and to estimate its potential human health risk. Farmed sea basses (Lates calcarifer) from Setiu Lagoon were used to study the difference in metal uptake through human consumption of raw and cooked (steamed) fish samples. Selected heavy metals, namely copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb), were measured using ICP-MS following Teflon bomb closed digestion of the fish samples. Cooking of the fish muscle by steaming was applied to investigate if cooking changes the concentration of heavy metals. Mercury and As were found accumulated more notably in the fish muscle, though only Hg was found to show significant (p > 0.05) increase when L. calcarifer is cooked. The amount of As in the fish muscle throughout its growth can be potentially harmful to humans, with the highest averaged concentration at 3.29 ± 0.65 mg/kg dw. above the standard set by the Malaysian Food Regulation (1985) of >1 mg/kg. All the other heavy metals were at relatively safe concentrations well below the standard set by both national and international guidelines. The PTWI per individual of L. calcarifer for As was at 0.84 mg/kg bw., which indicated that the amount of this fish safe for consumption without any adverse effect is 170 g/week. Therefore, long-term intake of these fish may pose a risk to human health due to the relatively higher Hg and As concentration found in these fishes.
    Matched MeSH terms: Mercury
  13. Wolswijk G, Satyanarayana B, Le QD, Siau YF, Ali ANB, Saliu IS, et al.
    Data Brief, 2020 Apr;29:105134.
    PMID: 32016142 DOI: 10.1016/j.dib.2020.105134
    This paper presents the results of mercury analysis on 786 abiotic (surface sediments) and biotic (plant and animal tissues) samples collected from 10 sites at Matang Mangrove Forest Reserve in Peninsular Malaysia. Sediment samples were collected at the surface level from both river bank and forest understory. Whereas plant tissues obtained from Rhizophora apiculata Blume and Rhizophora mucronata L. consisted of leaves (in four stages namely young, mature, senescent and decomposing), bark and roots (divided into xylem, cortex and epidermis), the animal samples were represented by muscle tissue of the gastropod Cassidula aurisfelis Bruguière and the cockle Tegillarca granosa L. The mercury concentration measurements were obtained through a cold vapor atomic absorption spectrometer. The core data have been analysed and interpreted in the paper "Distribution of mercury in sediments, plant and animal tissues in Matang Mangrove Forest Reserve, Malaysia" [1].
    Matched MeSH terms: Mercury
  14. Lee WH, Lai CW, Hamid SBA
    Materials (Basel), 2015 Aug 28;8(9):5702-5714.
    PMID: 28793530 DOI: 10.3390/ma8095270
    WO₃-decorated TiO₂ nanotube arrays were successfully synthesized using an in situ anodization method in ethylene glycol electrolyte with dissolved H₂O₂ and ammonium fluoride in amounts ranging from 0 to 0.5 wt %. Anodization was carried out at a voltage of 40 V for a duration of 60 min. By using the less stable tungsten as the cathode material instead of the conventionally used platinum electrode, tungsten will form dissolved ions (W(6+)) in the electrolyte which will then move toward the titanium foil and form a coherent deposit on the titanium foil. The fluoride ion content was controlled to determine the optimum chemical dissolution rate of TiO₂ during anodization to produce a uniform nanotubular structure of TiO₂ film. Nanotube arrays were then characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the FESEM images obtained, nanotube arrays with an average pore diameter of up to 65 nm and a length of 1.8 µm were produced. The tungsten element in the samples was confirmed by EDAX results which showed varying tungsten content from 0.22 to 2.30 at%. XRD and Raman results showed the anatase phase of TiO₂ after calcination at 400 °C for 4 h in air atmosphere. The mercury removal efficiency of the nanotube arrays was investigated by photoirradiating samples dipped in mercury chloride solution with TUV (Tube ultraviolet) 96W UV-B Germicidal light. The nanotubes with the highest aspect ratio (15.9) and geometric surface area factor (92.0) exhibited the best mercury removal performance due to a larger active surface area, which enables more Hg(2+) to adsorb onto the catalyst surface to undergo reduction to Hg⁰. The incorporation of WO₃ species onto TiO₂ nanotubes also improved the mercury removal performance due to improved charge separation and decreased charge carrier recombination because of the charge transfer from the conduction band of TiO₂ to the conduction band of WO₃.
    Matched MeSH terms: Mercury
  15. Sadrolhosseini AR, Noor AS, Bahrami A, Lim HN, Talib ZA, Mahdi MA
    PLoS One, 2014;9(4):e93962.
    PMID: 24733263 DOI: 10.1371/journal.pone.0093962
    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.
    Matched MeSH terms: Mercury/analysis
  16. Hajeb P, Jinap S
    J Agric Food Chem, 2012 Jun 13;60(23):6069-76.
    PMID: 22515475 DOI: 10.1021/jf300582j
    An acidic solution containing mercury chelating agents to eliminate mercury in raw fish (mackerel) fillet was developed. The solution contained hydrochloric acid, sodium hydroxide, cysteine, EDTA, and NaCl. The optimum conditions for mercury reduction were achieved using response surface methodology (RSM) at cysteine concentration of 1.25%, EDTA of 275 mg/L, NaCl of 0.5%, pH of 3.75, and exposure time of 18 min. The optimized conditions produced a solution which can remove up to 91% mercury from raw fish fillet. Cysteine and EDTA were identified as potential chelating agents with the greatest potential for use. The solution can be employed in fish industries to reduce mercury in highly contaminated fish.
    Matched MeSH terms: Mercury/isolation & purification*
  17. Amir Sultan MM, Goh CT, Wan Puteh SE, Mokhtar M
    Int J Health Care Qual Assur, 2019 Feb 11;32(1):34-44.
    PMID: 30859864 DOI: 10.1108/IJHCQA-08-2017-0161
    PURPOSE: Mercury is widely used in medical and healthcare facilities as dental amalgam, mercury-added medical devices, thiomersal-containing vaccines, laboratory analysis and for other general applications despite the hazards. Various agencies consistently promote mercury-free medical facilities through mercury-free alternatives and better management practices, which are in line with the Minamata Convention on Mercury that aims to protect human health and environment from anthropogenic mercury release. The paper aims to discuss these issues.

    DESIGN/METHODOLOGY/APPROACH: The authors conducted a gap analysis on recommended practices gathered from the literature and current practices gathered through semi-structured interviews with Malaysian medical personnel. A life cycle approach was adopted covering mercury use: input, storage, handling, accident, waste disposal and governance phases.

    FINDINGS: The authors found that there are significant gaps between recommended and current mercury management practices. Analysis indicates improper mercury management as the main contributor to these gaps. The authors found from recommended practices that core components needing improvement include: mercury management action plan, mercury use identification team, purchasing policy, proper guidelines and monitoring systems.

    PRACTICAL IMPLICATIONS: This study helps us to understand mercury management practices and suggests essential steps to establish a mercury-free medical facility.

    ORIGINALITY/VALUE: This study explored the gaps between recommended and current mercury management practices in a medical facility and contributes to the Minamata Convention on Mercury aspirations.

    Matched MeSH terms: Mercury/adverse effects*
  18. Ang HH, Lee KL
    Int J Toxicol, 2007 Sep-Oct;26(5):433-9.
    PMID: 17963130 DOI: 10.1080/10915810701583036
    The DCA (Drug Control Authority) of Malaysia implemented phase 3 registration of traditional medicines in January 1992 with special emphasis on the quality, efficacy, and safety of all dosage forms of these medicines. For this reason, a total of 100 herbal products containing Smilax myosotiflora were purchased in the Malaysian market and analyzed for mercury content, as mercury is a recognized reproductive toxicant. The products were analyzed using cold vapor atomic absorption spectrophotometry. It was found that 89% of the above products do not exceed 0.5 ppm of mercury. Heavy metal poisoning such as mercury has been associated with traditional medicines. Therefore, it is important that doctors and health care practitioners are aware of these risks and finding ways to minimize them, including questions pertaining to the use of these remedies during the routine taking of a patient's history.
    Matched MeSH terms: Mercury/analysis*
  19. Jamadon NK, Busairi N, Syahir A
    Protein Pept Lett, 2018;25(1):90-95.
    PMID: 29237368 DOI: 10.2174/0929866525666171214111503
    BACKGROUND: Mercury (II) ion, Hg2+ is among the most common pollutants with the ability to affect the environment. The implications of their elevation in the environment are mainly due to the industrialization and urbanization process. Current methods of Hg2+ detection primarily depend on sophisticated and expensive instruments. Hence, an alternative and practical way of detecting Hg2+ ions is needed to go beyond these limitations. Here, we report a detection method that was developed using an inhibitive enzymatic reaction that can be monitored through a smartphone. Horseradish peroxidase (HRP) converted 4-aminoantipyrene (4-AAP) into a red colored product which visible with naked eye. A colorless product, on the other hand, was produced indicating the presence of Hg2+ that inhibit the reaction.

    OBJECTIVES: The aim of this study is to develop a colorimetric sensor to detect Hg2+ in water sources using HRP inhibitive assay. The system can be incorporated with a mobile app to make it practical for a prompt in-situ analysis.

    METHODS: HRP enzyme was pre-incubated with different concentration of Hg2+ at 37°C for 1 hour prior to the addition of chromogen. The mix of PBS buffer, 4-AAP and phenol which act as a chromogen was then added to the HRP enzyme and was incubated for 20 minutes. Alcohol was added to stop the enzymatic reaction, and the change of colour were observed and analyse using UV-Vis spectrophotometer at 520 nm wavelength. The results were then analysed using GraphPad PRISM 4 for a non-linear regression analysis, and using Mathematica (Wolfram) 10.0 software for a hierarchical cluster analysis. The samples from spectroscopy measurement were directly used for dynamic light scattering (DLS) evaluation to evaluate the changes in HRP size due to Hg2+ malfunctionation. Finally, molecular dynamic simulations comparing normal and malfunctioned HRP were carried out to investigate structural changes of the HRP using YASARA software.

    RESULTS: Naked eye detection and data from UV-Vis spectroscopy showed good selectivity of Hg2+ over other metal ions as a distinctive color of Hg2+ is observed at 0.5 ppm with the IC50 of 0.290 ppm. The mechanism of Hg2+ inhibition towards HRP was further validated using a dynamic light scattering (DLS) and molecular dynamics (MD) simulation to ensure that there is a conformational change in HRP size due to the presence of Hg2+ ions. The naked eye detection can be quantitatively determined using a smartphone app namely ColorAssist, suggesting that the detection signal does not require expensive instruments to be quantified.

    CONCLUSION: A naked-eye colorimetric sensor for mercury ions detection was developed. The colour change due to the presence of Hg2+ can be easily distinguished using an app via a smartphone. Thus, without resorting to any expensive instruments that are mostly laboratory bound, Hg2+ can be easily detected at IC50 value of 0.29 ppm. This is a promising alternative and practical method to detect Hg2+ in the environment.

    Matched MeSH terms: Mercury/analysis*
  20. Mahat NA, Muktar NK, Ismail R, Abdul Razak FI, Abdul Wahab R, Abdul Keyon AS
    Environ Sci Pollut Res Int, 2018 Oct;25(30):30224-30235.
    PMID: 30155632 DOI: 10.1007/s11356-018-3033-8
    Contamination of toxic metals in P. viridis mussels has been prevalently reported; hence, health risk assessment for consuming this aquaculture product as well as the surrounding surface seawater at its harvesting sites appears relevant. Since Kampung Pasir Puteh, Pasir Gudang is the major harvesting site in Malaysia, and because the last heavy metal assessment was done in 2009, its current status remains unclear. Herein, flame atomic absorption spectrometry and flow injection mercury/hydride system were used to determine the concentrations of Pb, Cd, Cu and total Hg in P. viridis mussels and surface seawater (January-March 2015), respectively. Significantly higher concentrations of these metals were found in P. viridis mussels (p 
    Matched MeSH terms: Mercury/analysis
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