Displaying publications 1 - 20 of 44 in total

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  1. Rahman MM, Ahmad SH, Mohamed MT, Ab Rahman MZ
    ScientificWorldJournal, 2014;2014:635240.
    PMID: 25250382 DOI: 10.1155/2014/635240
    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15 mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  2. Chang ET, Lim BH
    Med J Malaysia, 1989 Jun;44(2):160-6.
    PMID: 2626126
    The abuse of phenylbutazone among rheumatoid arthritis patients has recently become a subject of interest. Unscrupulous manufacturers take advantage of the miraculous analgesic property of phenylbutazone and deliberately add this toxic drug in their preparations without declaring its presence on the label. In a recent survey, many such illicit preparations were seized from Chinese medical halls in Johor and sent to the Department of Chemistry, Johor Bahru for analysis. Here a Gas Chromatograph Mass Selective Detector (GC-MSD) method was developed for the determination of phenylbutazone in illicit traditional preparations.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  3. Moniruzzaman M, Rodríguez I, Ramil M, Cela R, Sulaiman SA, Gan SH
    Talanta, 2014 Nov;129:505-15.
    PMID: 25127626 DOI: 10.1016/j.talanta.2014.06.019
    The performance of gas chromatography (GC) combined with a hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) system for the determination of volatile and semi-volatile compounds in honey samples is evaluated. After headspace (HS) solid-phase microextraction (SPME) of samples, the accurate mass capabilities of the above system were evaluated for compounds identification. Accurate scan electron impact (EI) MS spectra allowed discriminating compounds displaying the same nominal masses, but having different empirical formulae. Moreover, the use of a mass window with a width of 0.005 Da provided highly specific chromatograms for selected ions, avoiding the contribution of interferences to their peak areas. Additional information derived from positive chemical ionization (PCI) MS spectra and ion product scan MS/MS spectra permitted confirming the identity of novel compounds. The above possibilities are illustrated with examples of honey aroma compounds, belonging to different chemical classes and containing different elements in their molecules. Examples of compounds whose structures could not be described are also provided. Overall, 84 compounds, from a total of 89 species, could be identified in 19 honey samples from 3 different geographic areas in the world. The suitability of responses measured for selected ions, corresponding to above species, for authentication purposes is assessed through principal components analysis.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  4. Zakaria A, Shakaff AY, Masnan MJ, Ahmad MN, Adom AH, Jaafar MN, et al.
    Sensors (Basel), 2011;11(8):7799-822.
    PMID: 22164046 DOI: 10.3390/s110807799
    The major compounds in honey are carbohydrates such as monosaccharides and disaccharides. The same compounds are found in cane-sugar concentrates. Unfortunately when sugar concentrate is added to honey, laboratory assessments are found to be ineffective in detecting this adulteration. Unlike tracing heavy metals in honey, sugar adulterated honey is much trickier and harder to detect, and traditionally it has been very challenging to come up with a suitable method to prove the presence of adulterants in honey products. This paper proposes a combination of array sensing and multi-modality sensor fusion that can effectively discriminate the samples not only based on the compounds present in the sample but also mimic the way humans perceive flavours and aromas. Conversely, analytical instruments are based on chemical separations which may alter the properties of the volatiles or flavours of a particular honey. The present work is focused on classifying 18 samples of different honeys, sugar syrups and adulterated samples using data fusion of electronic nose (e-nose) and electronic tongue (e-tongue) measurements. Each group of samples was evaluated separately by the e-nose and e-tongue. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were able to separately discriminate monofloral honey from sugar syrup, and polyfloral honey from sugar and adulterated samples using the e-nose and e-tongue. The e-nose was observed to give better separation compared to e-tongue assessment, particularly when LDA was applied. However, when all samples were combined in one classification analysis, neither PCA nor LDA were able to discriminate between honeys of different floral origins, sugar syrup and adulterated samples. By applying a sensor fusion technique, the classification for the 18 different samples was improved. Significant improvement was observed using PCA, while LDA not only improved the discrimination but also gave better classification. An improvement in performance was also observed using a Probabilistic Neural Network classifier when the e-nose and e-tongue data were fused.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  5. Nagappan T, Ramasamy P, Wahid ME, Segaran TC, Vairappan CS
    Molecules, 2011 Nov 21;16(11):9651-64.
    PMID: 22105714 DOI: 10.3390/molecules16119651
    A total of three carbazole alkaloids and essential oil from the leaves of Murraya koenigii (Rutaceae) were obtained and examined for their effects on the growth of five antibiotic resistant pathogenic bacteria and three tumor cell lines (MCF-7, P 388 and Hela). The structures of these carbazoles were elucidated based on spectroscopy data and compared with literature data, hence, were identified as mahanine (1), mahanimbicine (2) and mahanimbine (3). The chemical constituents of the essential oil were identified using Gas Chromatography-Mass Spectroscopy (GCMS). These compounds exhibited potent inhibition against antibiotic resistant bacteria such as Staphylococcus aureus (210P JTU), Psedomonas aeruginosa (ATCC 25619), Klebsiella pneumonia (SR1-TU), Escherchia coli (NI23 JTU) and Streptococcus pneumoniae (SR16677-PRSP) with significant minimum inhibition concentration (MIC) values (25.0-175.0 mg/mL) and minimum bacteriacidal concentrations (MBC) (100.0-500.0 mg/mL). The isolated compounds showed significant antitumor activity against MCF-7, Hela and P388 cell lines. Mahanimbine (3) and essential oil in particular showed potent antibacteria and cytotoxic effect with dose dependent trends (≤5.0 μg/mL). The findings from this investigation are the first report of carbazole alkaloids' potential against antibiotic resistant clinical bacteria, MCF-7 and P388 cell lines.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  6. Ying S, Lasekan O, Naidu KR, Lasekan S
    Molecules, 2012 Nov 22;17(12):13795-812.
    PMID: 23174897 DOI: 10.3390/molecules171213795
    Sensorial analysis of pineapple breads (conventionally baked, Cpb; fully baked frozen, Fpb and partially baked, Ppb) showed no significant differences in terms of aroma and taste. On the contrary, the scores for the overall quality between the partially baked and conventionally baked breads showed significant (p < 0.05) differences. At the same time, headspace analysis using a solid-phase microextraction (SPME) method identified 59 volatile compounds. The results of the aroma extracts dilution analysis (AEDA) revealed 19 most odour-active compounds with FD factors in the range of 32-128 as the key odourants of the pineapple breads. Further analysis of the similarities and differences between the pineapple breads in terms of the key odourants were carried out by the application of PLS-DA and PLS-regression coefficients. Results showed that Ppb exhibited strong positive correlations with most of the volatile- and non-volatile compounds, while the Cpb showed significant positive correlations with hexanal and 4-hydroxy-2,5-dimethyl-3(2H)-furanone, and the Fpb had strong positive correlations with lactic acid, benzoic acid, benzaldehyde and ethyl propanoate.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  7. Abdulhafiz F, Mohammed A, Kayat F, Bhaskar M, Hamzah Z, Podapati SK, et al.
    Molecules, 2020 Jun 08;25(11).
    PMID: 32521624 DOI: 10.3390/molecules25112658
    Alocasia longiloba, locally known as 'Keladi Candik', has been used traditionally to treat wounds, furuncle and joint inflammations. A. longiloba can be a new source of herbal medicine against hyperuricemia by inhibiting the activity of xanthine oxidase enzyme, the enzyme which is responsible for the development of hyperuricemia in human. Existing xanthine oxidase inhibitors (XOI drugs) show several side effects on gout patients. Therefore, an alternative herbal medicine from plants, with high therapeutic property and free of side effects, are greatly needed. This study was conducted to evaluate XO inhibitory activity, chemical composition, antioxidant activity and GC-MS profile of A. longiloba. Our results showed that ethanolic petiole extract exhibited the highest XO inhibitory activity (70.40 ± 0.05%) with IC50 value of 42.71 μg/mL, followed by ethanolic fruit extracts (61.44 ± 1.24%) with the IC50 value of 51.32 μg/mL. In a parallel study, the phytochemical analysis showed the presence of alkaloid, flavonoid, terpenoids, glycoside and saponin in petiole and fruit extracts, as well as higher total phenolic and flavonoid contents and strong scavenging activity on DPPH and ABTS antioxidant assay. The GC-MS analysis of fruit and petiole extracts revealed the presence of various compounds belonging to different chemical nature, among them are limonen-6-ol, α-DGlucopyranoside, paromomycin, aziridine, phenol, Heptatriacotanol, Phen-1,2,3-dimethyl and Betulin found in ethanolic fruit extract, and Phen-1,4-diol,2,3-dimethyl-, 1-Ethynyl-3,trans(1,1-dimethylethyl), Phenol,2,6-dimethoxy-4-(2-propenyl)- and 7-Methyl-Z-tetradecen-1-olacetate found in ethanolic petiole extract. Some compounds were documented as potent anti-inflammatory and arthritis related diseases by other researchers. In this study, the efficiency of solvents to extract bioactives was found to be ethanol > water, methanol > hexane > chloroform. Together, our results suggest the prospective utilization of fruit and petiole of A. longiloba to inhibit the activity of XO enzyme.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  8. Baharum SN, Bunawan H, Ghani MA, Mustapha WA, Noor NM
    Molecules, 2010 Oct 12;15(10):7006-15.
    PMID: 20944520 DOI: 10.3390/molecules15107006
    The essential oil in leaves of Polygonum minus Huds., a local aromatic plant, were identified by a pipeline of gas chromatography (GC) techniques coupled with mass-spectrometry (MS), flame ionization detector (FID) and two dimensional gas chromatography time of flight mass spectrometry (GC x GC-TOF MS). A total of 48 compounds with a good match and high probability values were identified using this technique. Meanwhile, 42 compounds were successfully identified in this study using GC-MS, a significantly larger number than in previous studies. GC-FID was used in determining the retention indices of chemical components in P. minus essential oil. The result also showed the efficiency and reliability were greatly improved when chemometric methods and retention indices were used in identification and quantification of chemical components in plant essential oil.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  9. Nurjuliana M, Che Man YB, Mat Hashim D, Mohamed AK
    Meat Sci, 2011 Aug;88(4):638-44.
    PMID: 21420795 DOI: 10.1016/j.meatsci.2011.02.022
    The volatile compounds of pork, other meats and meat products were studied using an electronic nose and gas chromatography mass spectrometer with headspace analyzer (GCMS-HS) for halal verification. The zNose™ was successfully employed for identification and differentiation of pork and pork sausages from beef, mutton and chicken meats and sausages which were achieved using a visual odor pattern called VaporPrint™, derived from the frequency of the surface acoustic wave (SAW) detector of the electronic nose. GCMS-HS was employed to separate and analyze the headspace gasses from samples into peaks corresponding to individual compounds for the purpose of identification. Principal component analysis (PCA) was applied for data interpretation. Analysis by PCA was able to cluster and discriminate pork from other types of meats and sausages. It was shown that PCA could provide a good separation of the samples with 67% of the total variance accounted by PC1.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  10. Ismail A, Toriman ME, Juahir H, Kassim AM, Zain SM, Ahmad WKW, et al.
    Mar Pollut Bull, 2016 Oct 15;111(1-2):339-346.
    PMID: 27397593 DOI: 10.1016/j.marpolbul.2016.06.089
    Extended use of GC-FID and GC-MS in oil spill fingerprinting and matching is significantly important for oil classification from the oil spill sources collected from various areas of Peninsular Malaysia and Sabah (East Malaysia). Oil spill fingerprinting from GC-FID and GC-MS coupled with chemometric techniques (discriminant analysis and principal component analysis) is used as a diagnostic tool to classify the types of oil polluting the water. Clustering and discrimination of oil spill compounds in the water from the actual site of oil spill events are divided into four groups viz. diesel, Heavy Fuel Oil (HFO), Mixture Oil containing Light Fuel Oil (MOLFO) and Waste Oil (WO) according to the similarity of their intrinsic chemical properties. Principal component analysis (PCA) demonstrates that diesel, HFO, MOLFO and WO are types of oil or oil products from complex oil mixtures with a total variance of 85.34% and are identified with various anthropogenic activities related to either intentional releasing of oil or accidental discharge of oil into the environment. Our results show that the use of chemometric techniques is significant in providing independent validation for classifying the types of spilled oil in the investigation of oil spill pollution in Malaysia. This, in consequence would result in cost and time saving in identification of the oil spill sources.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  11. Mokhtar SU, Chin ST, Kee CL, Low MY, Drummer OH, Marriott PJ
    J Pharm Biomed Anal, 2016 Mar 20;121:188-196.
    PMID: 26808068 DOI: 10.1016/j.jpba.2016.01.034
    Application of gas chromatography-triple quadrupole mass spectrometry for identification, confirmation and quantification of 6 phosphodiesterase-5 (PDE-5) inhibitors (sildenafil, dimethylsildenafil, homosildenafil, thiosildenafil, thiodimethylsildenafil and thiohomosildenafil) in dietary supplements was investigated. The MS was operated in multiple reaction monitoring mode, for better sensitivity and selectivity. In this manner, the method is adequate to reduce background noise with less interference from co-eluting compounds in the samples. Two different ionisation techniques, electron ionisation (EI) and chemical ionisation (CI), were studied and compared. The chromatographic separation was performed on a short 10 m non-polar capillary column without any derivatisation step. This permitted fast analysis for all analogues with retention time less than 11 min, for both techniques. Use of backflushing can aid method retention time reduction and improves column maintenance. Evaluation of method validation included limit of detection (LOD), lower limit of quantitation (LLOQ), linearity, precision and recovery were performed for both EI and CI techniques. The LOD obtained varied from 0.03 to 1.50 μg/g and the LLOQ ranged from 0.10 to 5.00 μg/g. Good calibration linearity was obtained for all analogues for both techniques, with correlation coefficients (r(2)) higher than 0.99. Mean recoveries of all analogues using CI show higher values (83.4-108.8%) than that of EI (61.9-91.1%). The intra- and inter-assay precisions were evaluated for all analogues at spiked concentration of 10 μg/g and the relative standard deviation was less than 15% for both methods. These methods were then successfully applied to dietary supplement samples without prior derivatisation, confirming that the samples were adulterated with sildenafil and/or its analogues.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  12. Ahmad Nizar NN, Nazrim Marikkar JM, Hashim DM
    J Oleo Sci, 2013;62(7):459-64.
    PMID: 23823911
    A study was conducted to differentiate lard, chicken fat, beef fat and mutton fat using Gas Chromatography Mass Spectrometry (GC-MS) and Elemental Analyzer-Isotope Ratio Mass Spectrometry (EA-IRMS). The comparison of overall fatty acid data showed that lard and chicken fat share common characteristics by having palmitic, oleic and linoleic acid as major fatty acids while beef and mutton fats shared common characteristics by possessing palmitic, stearic and oleic acid as major fatty acids. The direct comparisons among the fatty acid data, therefore, may not be suitable for discrimination of different animal fats. When the fatty acid distributional data was subjected to Principle Component Analysis (PCA), it was demonstrated that stearic, oleic and linoleic acids as the most discriminating parameters in the clustering of animal fats into four subclasses. The bulk carbon analysis of animal fats using EA-IRMS showed that determination of the carbon isotope ratios (δ¹³C) would be a good indicator for discriminating lard, chicken fat, beef fat and mutton fat. This would lead to a faster and more efficient method to ascertain the source of origin of fats used in food products.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  13. Javadi N, Abas F, Abd Hamid A, Simoh S, Shaari K, Ismail IS, et al.
    J Food Sci, 2014 Jun;79(6):C1130-6.
    PMID: 24888400 DOI: 10.1111/1750-3841.12491
    Cosmos caudatus, which is known as "Ulam Raja," is an herbal plant used in Malaysia to enhance vitality. This study focused on the evaluation of the α-glucosidase inhibitory activity of different ethanolic extracts of C. caudatus. Six series of samples extracted with water, 20%, 40%, 60%, 80%, and 100% ethanol (EtOH) were employed. Gas chromatography-mass spectrometry (GC-MS) and orthogonal partial least-squares (OPLS) analysis was used to correlate bioactivity of different extracts to different metabolite profiles of C. caudatus. The obtained OPLS scores indicated a distinct and remarkable separation into 6 clusters, which were indicative of the 6 different ethanol concentrations. GC-MS can be integrated with multivariate data analysis to identify compounds that inhibit α-glucosidase activity. In addition, catechin, α-linolenic acid, α-D-glucopyranoside, and vitamin E compounds were identified and indicate the potential α-glucosidase inhibitory activity of this herb.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  14. Manickavasagam G, Saaid M, Lim V
    J Food Sci, 2024 Feb;89(2):1058-1072.
    PMID: 38221804 DOI: 10.1111/1750-3841.16903
    Volatile organic compounds in honey are known for their considerable impact on the organoleptic properties of honey, such as aroma, flavor, taste, and texture. The type and composition of volatile organic compounds are influenced by entomological, geographical, and botanical origins; thus, these compounds have the potential to be chemical markers. Sixty-two volatile compounds were identified using gas chromatography-mass spectrometry from 30 Heterotrigona itama (H. itama) honey samples from 3 different geographical origins. Hydrocarbons and benzene derivatives were the dominant classes of volatile organic compounds in the samples. Both clustering and discriminant analyses demonstrated a clear separation between samples from distant origins (Kedah and Perak), and the volcano plot supported it. The reliability and predictability of the partial least squares-discriminant analysis model from the discriminant analysis were validated using cross-validation (R2 : 0.93; Q2 : 0.83; accuracy: 0.97) and the permutation test (p  1.0) and the Kruskal-Wallis test (p 
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods
  15. Firus Khan AY, Ahmed QU, Nippun TS, Hilles A, Jalal TK, Teh LK, et al.
    J Ethnopharmacol, 2020 Nov 15;262:113138.
    PMID: 32726681 DOI: 10.1016/j.jep.2020.113138
    ETHNOPHARMACOLOGICAL RELEVANCE: Porcupine bezoar (PB) is used as folk medicine for various medical conditions including cancer treatment in Malaysia. However, its toxicity profile has never been thoroughly ascertained to confirm its safe nature as an efficacious traditional medicine in the treatment of cancer as well as other ailments.

    AIM OF THE STUDY: This study was aimed to reveal three different PBs' aqueous extracts(viz. PB-A, PB-B, PB-C) chemical constituent's profile using GC-MS analysis, anticancer property on A375, HeLa and MCF7 cancer cells, toxicity profile on zebrafish embryo morphology, EC50, LC50 and teratogenicity index.

    MATERIALS AND METHODS: PBs' extracts characterization was performed through GC-MS analysis, in vitro anticancer effect was carried out on A375, HeLa and MCF7 cancer cell lines and finally and toxicity properties on three different PBs aqueous extracts (viz. PB-A, PB-B, PB-C) were determined using zebrafish embryo model.

    RESULTS: The GC-MS analysis revealed 10 similar compounds in all PBs' extracts. Dilauryl thiodipropionate was found to be a major compound in all PBs' extracts followed by tetradecanoic acid. An in vitro anticancer study revealed PB extracts exerted median inhibition concentration (IC50) <50 μg/mL, on cancer cells viz. A375, HeLa and MCF7 with no significant toxicity on normal cells viz. NHDF cells. In vivo toxicity of PBs extracts found affecting tail detachment, hatching, craniofacial, brain morphology, soft tissues, edema, spinal, somites, notochord and cardiovascular system (brachycardia, disruption of blood circulation) deformities. The LC50 and EC50 demonstrated PB extracts effect as dose and time dependent with median concentration <150.0 μg/mL. Additionally, teratogenicity index (TI) viz. >1.0 revealed teratogenic property for PB extracts.

    CONCLUSIONS: The findings revealed that all three PBs aqueous extracts possessed anticancer activity and exhibited significant toxicological effects on zebrafish embryos with high teratogenicity index. Hence, its use as an anticancer agent requires further investigation and medical attentions to determine its safe dose.

    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  16. Halimah M, Tan YA, Aini K, Ismail BS
    J Environ Sci Health B, 2003 Jul;38(4):429-40.
    PMID: 12856925
    Improved methods for extraction and clean up of fluroxypyr residue in water have been established. Two methods of fluroxypyr extraction were used, namely, Direct Measurement of fluroxypyr and Concentration of fluroxypyr onto A Solid Phase Extraction (SPE) Adsorbent, followed by elution with solvent before determination of fluroxypyr. The recovery for Direct Measurement of fluroxypyr in water containing 8-100 microg L(-1), ranged from 86 to 110% with relative standard deviation of 0.7 to 2.15%. For the second method, three types of SPE were used, viz. C18, C18 end-capped and polyvinyl dibenzene (ISOLUTE ENV+). The procedure involved concentrating the analyte from fluroxypyr-spiked water at pH 3, followed by elution of the analyte with 4 mL of acentonitrile. The recovery of fluroxypyr from the spiked sample at 1 to 50 microg L(-1) after eluting through either C18 or C18 end-capped ranged from 40-64% (with relative standard deviation of 0.7 to 2.15) and 41-65% (with standard deviation of 1.52 to 11.9). The use of ISOLUTE ENV+, gave better results than the C18, C18 end-capped or the Direct Measurement Methods. The recovery and standard deviation of fluroxypyr from spiked water using ISOLUTE ENV+ ranged from 91-102% and 2.5 to 5.3, respectively.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  17. Man CN, Gam LH, Ismail S, Lajis R, Awang R
    PMID: 16908224
    Nicotine is a major addictive compound in cigarette. Its smoke is rapidly and extensively metabolized to several metabolites in human. Cotinine as a major metabolite of nicotine is commonly used as a biomarker to determine active and passive smokers. Cotinine has a longer half-life ( approximately 20 h) compared to nicotine ( approximately 2h). A simple, sensitive, rapid and high throughput GC-MS method was developed for simultaneous quantification of urinary nicotine and cotinine in passive and active smokers. In the sample preparation method, the analytes and internal standard were first basified and followed by liquid-liquid extraction. Upon completion, anhydrous sodium sulphate was added to the solvent mixture to trap moistures. The clear extract obtained was directly injected into GC-MS, operating under selective ion monitoring (SIM) mode. Calibration curves in the range of 0.5-5000 ng/mL of the analytes in urine matrix were established with linear correlation coefficients (r(2)) greater than 0.997. The limit of detection for both nicotine and cotinine were 0.20 ng/mL. The mean recoveries for nicotine and cotinine were 93.0 and 100.4%, respectively. The within- and between-assay accuracies were between 2.1 and 7.9% for nicotine and between 0.7 and 11.1% for cotinine. Within- and between-assay precisions of 3.3-9.5% for nicotine and 3.4-9.8% for cotinine were also achieved. The method can be used in routine assessment and monitoring of active smoking and exposure to environmental tobacco smoke. The applicability of the assay was demonstrated in a small-scale comparison study between smokers and non-smokers.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  18. Wan Raihana WA, Gan SH, Tan SC
    PMID: 21147046 DOI: 10.1016/j.jchromb.2010.10.037
    Amphetamine-type stimulants (ATS) are a group of chiral amine drugs which are commonly abused for their sympathomimetic and stimulant properties. ATS are extensively metabolised by hepatic cytochrome P450 enzymes. As metabolism of ATS has been shown to be highly stereospecific, stereoselective analytical methods are essential for the quantitative determination of ATS concentrations for both in vivo and in vitro studies of ATS metabolism. This paper describes a new stereoselective method for the simultaneous determination of amphetamine (AM), methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 4-hydroxy-3-methoxymethamphetamine (HMMA), 4-hydroxy-3-methoxyamphetamine (HMA), 3,4-hydroxymethamphetamine (HHMA) and 3,4-hydroxyamphetamine (HHA) in human urine samples validated according to the United States Food and Drug Administration guidelines. In this method, analytes are simultaneously extracted and derivatized with R-(-)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride (R-MTPCl) as the chiral derivatization reagent. Following this, the analytes were subjected to a second derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) which targets the hydroxyl groups present in HMMA, HMA, HHMA and HHA. The derivatized analytes were separated and quantified using gas chromatography-mass spectrometry (GC-MS). The method was evaluated according to the established guidelines for specificity, linearity, precision, accuracy, recovery and stability using a five-day protocol. Intra-day precision ranged from 0.89 to 11.23% RSD whereas inter-day precision was between 1.03 and 12.95% RSD. Accuracy values for the analytes ranged from -5.29% to 13.75%. Limits of quantitation were 10 μg/L for AM, MA, MDMA, HMA and HMMA and 2μg/L for MDA, HMA and HHA. Recoveries and stability values were also within accepted values. The method was applied to authentic ATS-positive samples.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  19. Moniruzzaman M, Rodríguez I, Rodríguez-Cabo T, Cela R, Sulaiman SA, Gan SH
    J Chromatogr A, 2014 Nov 14;1368:26-36.
    PMID: 25441341 DOI: 10.1016/j.chroma.2014.09.057
    The suitability of the dispersive liquid-liquid microextraction (DLLME) technique for gas chromatography (GC) characterization of minor organic compounds in honey samples is evaluated. Under optimized conditions, samples were pre-treated by liquid-liquid extraction with acetonitrile followed by DLLME using carbon tetrachloride (CCl4, 0.075 mL) as extractant. The yielded settled phase was analyzed by GC using high resolution time-of-flight (TOF) mass spectrometry (MS). The whole sample preparation process is completed in approximately 10 min, with a total consumption of organic solvents below 4 mL, relative standard deviations lower than 12% and with more than 70 organic compounds, displaying linear retention index in the range from 990 to 2900, identified in the obtained extracts. In comparison with HS SPME extraction, higher peak intensities were attained for most volatile and semi-volatile compounds amenable to both extraction techniques. Furthermore, other species such as highly polar and water soluble benzene acids, long chain fatty acids, esters and flavonoids, which are difficult to concentrate by HS SPME, could be identified in DLLME extracts. Some of the compounds identified in DLLME extracts have been proposed as useful for samples classification and/or they are recognized as markers of honeys from certain geographic areas.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
  20. Sanagi MM, Loh SH, Wan Ibrahim WA, Hasan MN
    J Chromatogr A, 2012 Nov 2;1262:43-8.
    PMID: 23021646 DOI: 10.1016/j.chroma.2012.09.007
    Agarose film liquid phase microextraction (AF-LPME) procedure for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) in water has been investigated. Agarose film was used for the first time as an interface between donor and acceptor phases in liquid phase microextraction which allowed for selective extraction of the analytes prior to gas chromatography-mass spectrometry. Using 1-octanol as acceptor phase, high enrichment factors in the range of 57-106 for the targeted analytes (fluorene, phenanthrene, fluoranthene and pyrene) were achieved. Under the optimum extraction conditions, the method showed good linearity in the range of 0.1-200 μgL(-1), good correlation coefficients in the range of 0.9963-0.9999, acceptable reproducibility (RSD 6.1-9.2%, n=3), low limits of detection (0.01-0.04 μgL(-1)) and satisfactory relative recoveries (92.9-104.7%). As the AF-LPME device was non-expensive, reuse or recycle of the film was not required, thus eliminating the possibility of analytes carry-over between runs. The AF-LPME technique is environment-friendly and compatible with the green chemistry concept as agarose is biodegradable polysaccharide extracted from seaweed and the procedure requires small volume of organic solvent and generates little waste. The validated method was successfully applied to the analysis of the four analytes in river water samples.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry/methods*
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