Displaying all 9 publications

  1. Muhamad H, Zainol M, Sahid I, Abu Seman I
    Drug Test Anal, 2012 Aug;4 Suppl 1:112-7.
    PMID: 22851367 DOI: 10.1002/dta.1351
    In oil palm plantations, the fungicide hexaconazole is used to control Ganoderma infection that threatens to destroy or compromisethe palm. The application of hexaconazole is usually through soil drenching, trunk injection, or a combination of these two methods. It is therefore important to have a method to determine the residual amount of hexaconazole in the field such as in samples of water, soil, and leaf to monitor the use and fate of the fungicide in oil palm plantations. This study on the behaviour of hexaconazole in oil palm agro-environment was carried out at the UKM-MPOB Research Station, Bangi Lama, Selangor. Three experimental plots in this estate with 7-year-old Dura x Pisifera (DxP) palms were selected for the field trial. One plot was sprayed with hexaconazole at the manufacturer's recommended dosage, one at double the recommended dosage, and the third plot was untreated control. Hexaconazole residues in the soil, leaf, and water were determined before and after fungicide treatment. Soil samples were randomly collected from three locations at different depths (0-50 cm) and soil collected fromthe same depth were bulked together. Soil, water, and palm leaf were collected at -1 (day before treatment), 0 (day of treatment), 1, 3, 7, 14, 21, 70, 90, and 120 days after treatment. Hexaconazole was detected in soil and oil palm leaf, but was not detected in water from the nearby stream.
  2. Jaafar SN, Coelho AV, Sheehan D
    Drug Test Anal, 2015 Oct;7(10):957-66.
    PMID: 25833337 DOI: 10.1002/dta.1786
    Veterinary and human pharmaceuticals are an emerging category of chemical pollutants with potential to cause serious toxicity to non-target organisms. Filter-feeding aquatic organisms such as mussels are especially threatened. In this study, the blue mussel, Mytilus edulis, was exposed to two doses (0.2 mg/L and 1 mg/L) of the anti-inflammatory diclofenac. Effects on the gill, the principal feeding organ of mussels, were investigated. It was noted that, while no effect was evident on gill glutathione transferase or catalase activities, there was a tissue-specific increase in glutathione reductase activity and reduction in total protein thiol groups. Two dimensional electrophoresis was performed and some affected proteins identified by in-gel tryptic digestion and peptide mass fingerprinting. Of these, four unique proteins (caspase 3/7-4, heat-shock cognate protein 70, a predicted enolase-like protein, arginine kinase) were found to be oxidized whilst eight unique proteins (β-tubulin, actin, isocitrate dehydrogenase, arginine kinase, heavy metal-binding HIP, cytosolic malate dehydrogenase, proteasome subunit alpha type 2, Mg: bb02e05 (glyceraldehyde-3-phosphate dehydrogenase) and superoxide dismutase) were found to have altered abundance. In addition, bioinformatic analysis suggested putative identities for six hypothetical proteins which either were oxidized or decreased in abundance. These were; 78 kDa glucose-regulated protein precursor, α-enolase, calreticulin, mitochondrial H + -ATPase, palmitoyl protein thioesterase 1 and initiation factor 5a. It is concluded that diclofenac causes significant oxidative stress to gills and that this affects key structural, metabolic and stress-response proteins.
  3. Zeng Y, Xu Y, Kee CL, Low MY, Ge X
    Drug Test Anal, 2016 Mar;8(3-4):351-6.
    PMID: 26305055 DOI: 10.1002/dta.1846
    In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) with scheduled multiple reaction monitoring (MRM) enhanced product ion (EPI) method was developed for simultaneous determination of 40 compounds with weight loss effect, including bisacodyl, phenolphthalein, and sibutramine and its metabolites, etc. They might be adulterated in health supplements to get prominent weight loss effect. The samples were analyzed using a Q-Trap 5500 coupled with high performance liquid chromatography (HPLC) and a CORTECS ultra performance liquid chromatography (UPLC) C18 column (100 mm x 2.1 mm x1.6 µm). Scheduled MRM was used as survey scan, MS2 spectra acquired in the EPI mode were used to perform library searching to increase the confidence of detection. Limits of detection were less than 10 ng/g for the majority of the analytes. A total of 447 weight loss products were tested in our laboratory in the past three years. Among these samples, 119 samples were found to be adulterated with one or more weight loss compounds, including sibutramine, its metabolites benzyl sibutramine and desmethyl sibutramine; phenolphthalein; bisacodyl; furosemide; liothyronine (T3); and thyroxine (T4). Copyright © 2015 John Wiley & Sons, Ltd.
  4. Singh GK, Jimenez M, Newman R, Handelsman DJ
    Drug Test Anal, 2014 Apr;6(4):336-41.
    PMID: 23606665 DOI: 10.1002/dta.1481
    Urine provides a convenient non-invasive alternative to blood sampling for measurement of certain hormones. Urinary luteinizing hormone (LH) measurements have been used for endocrinology research and anti-doping testing. However, the commercially available LH immunoassays are developed and validated for human blood samples but not urine so that LH assays intended for use with urine samples need thorough validation. Therefore, the present study evaluated the measurement of urinary LH immunoreactivity using previously validated immunofluorometric (IF) and immunochemiluminometric (ICL) LH assays after prolonged frozen storage. LH was measured in serial urine samples following administration of a single injection of one of two doses of recombinant human chorionic hormone (rhCG) with assays run at the end of study (2008) and again after four years of frozen (-20 °C) storage where samples were stored without adding preservatives. The ICL assay showed quantitatively reproducible LH measurements after prolonged -20 °C storage. However, the IF immunoassay gave consistently lower LH levels relative to ICL (2008) with a further proportionate reduction after four years of sample storage (2012). Yet, both the assays displayed similar patterns of the time-course of urine LH measurement both before and after four years of frozen storage. In conclusion, we found that both immunoassays are suitable for urinary LH measurements with ICL assay being more robust for quantitative urinary LH measurement such as for anti-doping purposes, whereas the IF could be applicable for research studies where urine LH levels are compared within-study but not in absolute terms.
  5. Sulaiman M, Kunalan V, Yap ATW, Lim WJL, Ng JJY, Loh SWX, et al.
    Drug Test Anal, 2018 Jan;10(1):109-119.
    PMID: 28670869 DOI: 10.1002/dta.2238
    Clandestine heroin laboratories have been a feature of the Malaysian illicit drug scene since soon after the abuse of heroin emerged in 1972. The first few clandestine heroin laboratories which synthesised heroin via the acetylation of imported morphine were uncovered in 1973 and 1977. By the mid-1980s, this type of laboratory was replaced by heroin-cutting laboratories whereby imported high-grade heroin was cut to street heroin. This was to meet the rising demand for the drug owing to the rapid escalation of the number of drug users. Over the years, the most significant change in the composition of the street heroin is the decrease in its purity from 30%-50% to 3%-5%. Caffeine has remained the major adulterant and chloroquine is detected in virtually all recent seizures.
  6. Lim WJ, Yap AT, Mangudi M, Hu CY, Yeo CY, Eyo ZW, et al.
    Drug Test Anal, 2017 Mar;9(3):491-499.
    PMID: 27367276 DOI: 10.1002/dta.2034
  7. Sharma A, Kamble SH, León F, Chear NJ, King TI, Berthold EC, et al.
    Drug Test Anal, 2019 Aug;11(8):1162-1171.
    PMID: 30997725 DOI: 10.1002/dta.2604
    Kratom (Mitragyna speciosa) is a psychoactive plant popular in the United States for the self-treatment of pain and opioid addiction. For standardization and quality control of raw and commercial kratom products, an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantification of ten key alkaloids, namely: corynantheidine, corynoxine, corynoxine B, 7-hydroxymitragynine, isocorynantheidine, mitragynine, mitraphylline, paynantheine, speciociliatine, and speciogynine. Chromatographic separation of diastereomers, or alkaloids sharing same ion transitions, was achieved on an Acquity BEH C18 column with a gradient elution using a mobile phase containing acetonitrile and aqueous ammonium acetate buffer (10mM, pH 3.5). The developed method was linear over a concentration range of 1-200 ng/mL for each alkaloid. The total analysis time per sample was 22.5 minutes. The analytical method was validated for accuracy, precision, robustness, and stability. After successful validation, the method was applied for the quantification of kratom alkaloids in alkaloid-rich fractions, ethanolic extracts, lyophilized teas, and commercial products. Mitragynine (0.7%-38.7% w/w), paynantheine (0.3%-12.8% w/w), speciociliatine (0.4%-12.3% w/w), and speciogynine (0.1%-5.3% w/w) were the major alkaloids in the analyzed kratom products/extracts. Minor kratom alkaloids (corynantheidine, corynoxine, corynoxine B, 7-hydroxymitragynine, isocorynantheidine) were also quantified (0.01%-2.8% w/w) in the analyzed products; however mitraphylline was below the lower limit of quantification in all analyses.
  8. Mohd Yusop AY, Xiao L, Fu S
    Drug Test Anal, 2020 May 22.
    PMID: 32441056 DOI: 10.1002/dta.2861
    The lucrative market of herbal remedies spurs rampant adulteration, particularly with pharmaceutical drugs and their unapproved analogues. A comprehensive screening strategy is, therefore, warranted to detect these adulterants and, accordingly, to safeguard public health. This study uses the data-dependent acquisition of liquid chromatography-quadrupole time-of-flight-mass spectrometry (LC-QTOF-MS) to screen phosphodiesterase 5 (PDE5) inhibitors in herbal remedies using suspected-target and non-targeted strategies. For the suspected-target screening, we used a library comprising 95 PDE5 inhibitors. For the non-targeted screening, we adopted top-down and bottom-up approaches to flag novel PDE5 inhibitor analogues based on common fragmentation patterns. LC-QTOF-MS was optimised and validated for capsule and tablet dosage forms using 23 target analytes, selected to represent different groups of PDE5 inhibitors. The method exhibited excellent specificity and linearity with limit of detection and limit of quantification of <40 and 80 ng/mL, respectively. The accuracy ranged from 79.0% to 124.7% with a precision of <14.9% relative standard deviation. The modified, quick, easy, cheap, effective, rugged, and safe extraction provided insignificant matrix effect within -9.1%-8.0% and satisfactory extraction recovery of 71.5%-105.8%. These strategies were used to screen 52 herbal remedy samples that claimed to enhance male sexual performance. The suspected-target screening resulted in 33 positive samples, revealing 10 target analytes and 2 suspected analytes. Systematic MS and tandem MS interrogations using the non-targeted screening returned insignificant signals, indicating the absence of potentially novel analogues. The target analytes were quantified from 0.03 to 121.31 mg per dose of each sample. The proposed strategies ensure that all PDE5 inhibitors are comprehensively screened, providing a useful tool to curb the widespread adulteration of herbal remedies.
  9. Sulaiman N, Chee Beng Y, Ahmad Bustamam FK, Khairuddin NSK, Muhamad H
    Drug Test Anal, 2020 Apr;12(4):504-513.
    PMID: 31898859 DOI: 10.1002/dta.2760
    Cypermethrin is a pyrethroid insecticide commonly used to control bagworm infestation in oil palm plantations. It is applied through spraying onto the leaves where the bagworms reside. This article reports the fate of cypermethrin used in a Malaysian oil palm plantation during a typical dry season through the analysis of cypermethrin residue in environmental and palm oil samples collected from a supervised field trial. Residues of cypermethrin were not detected in the soil samples collected at different depths, water samples collected at different points in the experimental plots, and oil samples extracted from fresh fruit bunches (FFB) harvested from each plot for both single and double dosages of treatment throughout the study interval. Analysis of leaf samples, however, revealed that cypermethrin residue was detected for both pesticide treatments up to day 2 after cypermethrin application.
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