Displaying publications 41 - 60 of 1709 in total

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  1. Determination of pesticide residues in leafy vegetables at parts per billion levels by a chemometric study using GC-ECD in Cameron Highlands, Malaysia
    Farina Y, Abdullah MP, Bibi N, Khalik WM
    Food Chem, 2017 Jun 01;224:55-61.
    PMID: 28159293 DOI: 10.1016/j.foodchem.2016.11.113
    A simple and sensitive analytical method has been developed employing gas chromatography coupled with electron capture detector (GC-ECD), and validated for screening and quantification of 15 pesticide residues at trace levels in cabbage, broccoli, cauliflower, lettuce, celery, spinach, and mustard. The method consists of two steps, first, to determine the significance of each factor by Pareto chart followed by optimization of these significant factors using central composite design (CCD). Minitab statistical software was used for these multivariate experiments for the generation of 2(4-1) design and CCD matrices. The method evaluation was done by external standard calibration with linearity range between 0.5 and 3mg/kg, with correlation coefficient 0.99, limit of detection (LOD) ranges between 0.02 and 4.5ng/g, and limit of quantification (LOQ) ranges between 0.2 and 45ng/g. The average recovery was between 60% and 128%, with RSD 0.2-19.8%. The method was applied on real vegetable samples from Cameron Highlands.
    Matched MeSH terms: Chromatography, Gas/methods*
  2. Efficiency of Hollow Fiber Liquid-Phase Microextraction Chromatography Methods in the Separation of Organic Compounds: A Review
    Alsharif AM, Tan GH, Choo YM, Lawal A
    J Chromatogr Sci, 2017 03 01;55(3):378-391.
    PMID: 27903555 DOI: 10.1093/chromsci/bmw188
    Hollow fiber liquid-phase microextraction (HF-LPME) techniques coupled to chromatographic systems have been widely used for extraction and determination of diverse compounds. HF-LPME was able to provide better results in precision, accuracy, selectivity and enrichment factor, in addition to reduction of matrix effect and carry over. It is applicable within a wide pH range and compatible with most analytical instruments which enable the utilization of HF-LPME in a wide variety of applications. This review focused on the modified HF-LPME techniques, efficiency, comparison to other LPME methods and applications.
    Matched MeSH terms: Chromatography, Liquid/methods*
  3. Fulltext Pressurized Liquid Extraction of Polycyclic Aromatic Hydrocarbons from soil samples
    Noorashikin Md Saleh, Sanagi, M. Marsin
    Pertanika Journal of Science & Technology, 2011;19(1):25-32.
    MyJurnal
    A Pressurized Liquid Extraction (PLE) method was developed by using conventional High Performance
    Liquid Chromatography (HPLC). It was found that all of the PAHs have been successfully extracted with dichloromethane-acetone with high percentage recovery. A high temperature of 180°C gave the highest recovery for fluoranthene (94.4%). Meanwhile, fluorene showed the highest recovery at 150 bar, with 94.6% recovery. It is noted that there is no significant day-to-day difference in the efficiency of the developed method, with the R.S.D. values averaging at 0.02. The optimized conditions applied to the soil samples were analysed using the High Temperature High Performance Liquid Chromatography (HT-HPLC) with chromatographic conditions: Octadecylsilyl-silica (ODSsilica) column (100 mm × 4.6 mm I.D.); mobile phase acetonitrile:water 40:60 (v/v); flow rate 2.5 mL/min; temperature 70°C; UV absorbance 254 nm; injection volume 5µL.
    Matched MeSH terms: Chromatography, High Pressure Liquid; Chromatography, Liquid
  4. A simple, selective, and sensitive gas chromatography-mass spectrometry method for the analysis of five process-related impurities in atenolol bulk drug and capsule formulations
    Reddy AVB, Yusop Z, Jaafar J, Bin Aris A, Abdul Majid Z
    J Sep Sci, 2017 Aug;40(15):3086-3093.
    PMID: 28581679 DOI: 10.1002/jssc.201700252
    An extremely sensitive and simple gas chromatography with mass spectrometry method was developed and completely validated for the analysis of five process-related impurities, viz., 4-hydroxy-l-phenylglycine, 4-hydroxyphenylacetonitrile, 4-hydroxyphenylacetic acid, methyl-4-hydroxyphenylacetate, and 2-[4-{(2RS)-2-hydroxy-3-[(1-methylethyl)amino]propoxy}phenyl]acetonitrile, in atenolol. The separation of impurities was accomplished on a BPX-5 column with dimensions of 50 m × 0.25 mm i.d. and 0.25 μm film thickness. The method validation was performed following International Conference on Harmonisation guidelines in which the method was capable to quantitate 4-hydroxy-l-phenylglycine, 4-hydroxyphenylacetonitrile, and 4-hydroxyphenylacetic acid at 0.3 ppm, and methyl-4-hydroxyphenylacetate and 2-[4-{(2RS)-2-hydroxy-3-[(1-methylethyl)amino]propoxy}phenyl]acetonitrile at 0.35 ppm with respect to 10 mg/mL of atenolol. The method was linear over the concentration range of 0.3-10 ppm for 4-hydroxy-l-phenylglycine, 4-hydroxyphenylacetonitrile, and 4-hydroxyphenylacetic acid, and 0.35-10 ppm for methyl-4-hydroxyphenylacetate and 2-[4-{(2RS)-2-hydroxy-3-[(1-methylethyl)amino]propoxy}phenyl]acetonitrile. The correlation coefficient in each case was found ≥0.998. The repeatability and recovery values were acceptable, and found between 89.38% and 105.60% for all five impurities under optimized operating conditions. The method developed here is simple, selective, and sensitive with apparently better resolution than the reported methods. Hence, the method is a straightforward and good quality control tool for the quantitation of selected impurities at trace concentrations in atenolol.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry*
  5. Improving oil classification quality from oil spill fingerprint beyond six sigma approach
    Juahir H, Ismail A, Mohamed SB, Toriman ME, Kassim AM, Zain SM, et al.
    Mar Pollut Bull, 2017 Jul 15;120(1-2):322-332.
    PMID: 28535957 DOI: 10.1016/j.marpolbul.2017.04.032
    This study involves the use of quality engineering in oil spill classification based on oil spill fingerprinting from GC-FID and GC-MS employing the six-sigma approach. The oil spills are recovered from various water areas of Peninsular Malaysia and Sabah (East Malaysia). The study approach used six sigma methodologies that effectively serve as the problem solving in oil classification extracted from the complex mixtures of oil spilled dataset. The analysis of six sigma link with the quality engineering improved the organizational performance to achieve its objectivity of the environmental forensics. The study reveals that oil spills are discriminated into four groups' viz. diesel, hydrocarbon fuel oil (HFO), mixture oil lubricant and fuel oil (MOLFO) and waste oil (WO) according to the similarity of the intrinsic chemical properties. Through the validation, it confirmed that four discriminant component, diesel, hydrocarbon fuel oil (HFO), mixture oil lubricant and fuel oil (MOLFO) and waste oil (WO) dominate the oil types with a total variance of 99.51% with ANOVA giving Fstat>Fcritical at 95% confidence level and a Chi Square goodness test of 74.87. Results obtained from this study reveals that by employing six-sigma approach in a data-driven problem such as in the case of oil spill classification, good decision making can be expedited.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry*
  6. Fulltext Formulation of chelating agent with surfactant in cloud point extraction of methylphenol in water
    Hazrina HZ, Noorashikin MS, Beh SY, Loh SH, Zain NNM
    R Soc Open Sci, 2018 Jul;5(7):180070.
    PMID: 30109066 DOI: 10.1098/rsos.180070
    Cloud point extraction (CPE) is a separation and preconcentration of non-ionic surfactant from one liquid phase to another. In this study, Sylgard 309 and three different types of additives for CPE, namely CPE-Sylgard, CPE-Sylgard-BMIMBr and CPE-Sylgard-GLDA, are investigated to extract methylphenol from water samples. The methylphenols are well separated by reversed-phase high-performance liquid chromatography (HPLC) with isocratic elution of acetonitrile : water; 60 : 40 (v/v) and detection at 260 nm. The optimized parameters for the effect of salt, surfactant, temperature, time of extraction, pH, interference study and the performance of different additives on methylphenol extraction are investigated. CPE-Sylgard-GLDA is chosen because it gives us a high peak and good peak area compared with CPE-Sylgard and CPE-Sylgard-BMIMBr. The recovery extractions of CPE-Sylgard-GLDA are obtained in the range of 80-99% as the percentage of relative standard deviation (RSD) is less than 10. The LOD and LOQ are 0.05 ppm and 0.18 ppm, respectively. The method developed for CPE-Sylgard-GLDA coupled with HPLC is feasible for the determination of methylphenol because it is simple, effective, cheap, and produces a high percentage of recovery.
    Matched MeSH terms: Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase
  7. Screening of nanoemulsion components for asenapine maleate using validated RP-HPLC method
    Kumbhar SA, Kokare CR, Shrivastava B, Gorain B
    Ann Pharm Fr, 2020 May 06.
    PMID: 32387177 DOI: 10.1016/j.pharma.2020.04.005
    A novel, simple reversed-phase high-performance liquid chromatographic (RP-HPLC) analytical method was developed and validated for the quantitative determination of asenapine from various nanoemulsion components during pre-formulation screening. The developed method was validated according to ICH Q2 (R1) guidelines. The developed and validated method was precisely and accurately quantified asenapine in various oils, surfactants and co-surfactants. The separation of asenapine was carried out on Hypersil BDS C18, 250×4.6mm, 5μm particle size column using methanol: acetonitrile (90:10) as mobile phase with a flow rate of 1mL.min-1. Measurement at 270nm for the concentration range of 5 to 50μg.mL-1 of the analyte was found to be linear with the determination coefficient (r2) of 0.999 as calculated by the least square regression method. The validated method was sensitive with LOD of 10.0ng.mL-1 and LOQ of 30.0ng.mL-1. Further, the method was precise and accurate, where the intraday and interday precision values were ranged from 0.70-0.95 and 0.36-0.95, respectively with the corresponding accuracy were ranged from 98.80-100.63 and 98.36-100.63. This developed and validated RP-HPLC method for asenapine was applied in the quantitative determination and screening of various oils, surfactants, and co-surfactants during the development of the asenapine maleate nanoemulsion.
    Matched MeSH terms: Chromatography, High Pressure Liquid; Chromatography, Reverse-Phase
  8. Determination of four lignans in Phyllanthus niruri L. by a simple high-performance liquid chromatography method with fluorescence detection
    Murugaiyah V, Chan KL
    J Chromatogr A, 2007 Jun 22;1154(1-2):198-204.
    PMID: 17418855 DOI: 10.1016/j.chroma.2007.03.079
    A new and simple analytical method using HPLC with fluorescence detection was developed for the simultaneous determination of four lignans (phyllanthin, hypophyllanthin, phyltetralin and niranthin) in Phyllanthus niruri L. plant samples. Optimal separation was achieved with an isocratic mobile phase consisting of acetonitrile-water (55:45 v/v). The method recorded limits of detection (S/N=5) for phyllanthin at 0.61 ng/mL, hypophyllanthin at 6.02 ng/mL, phyltetralin at 0.61 ng/mL and niranthin at 1.22 ng/mL, being 80, 8, 80 and 40 times, respectively, lower when compared with those derived using HPLC-UV detection. The limits of quantification (S/N=12) were 4.88 ng/mL for phyllanthin and phyltetralin, 9.76 ng/mL for niranthin and 24.4 ng/mL for hypophyllanthin showing 40, 8 and 20 times, respectively, lower than those from the UV detection method. The within-day and between-day accuracy for the four lignans were between 98.1% and 102.9% while their precision values were below 2.2%. The mean recovery was between 92.5% and 110.1%. The method was then successfully applied for the quantification of lignans in P. niruri plant samples. The highest amount of lignans was found in the leaves followed by fruits, branches and stem, whilst the roots have the least amount of lignans.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods*
  9. Observation and explanation of two-dimensional interconversion of oximes with multiple heart-cutting using comprehensive multidimensional gas chromatography
    Kulsing C, Nolvachai Y, Wong YF, Glouzman MI, Marriott PJ
    J Chromatogr A, 2018 Apr 20;1546:97-105.
    PMID: 29548566 DOI: 10.1016/j.chroma.2018.02.035
    Real-time interconversion processes produce unconventional peak broadening in gas chromatography (GC), and can be used to generate kinetic and thermodynamic data. In this study, an unusual separation situation in comprehensive two dimensional GC where two dimensional interconversion (i.e. a raised plateau in both first and second dimension, 1D and 2D) was observed in analysis of oxime isomers. This resulted in a characteristic and unusual rectangular peak shape in the two dimensional result. A related theoretical approach was introduced to explain the peak shape supported by simulation results which can be varied depending on concentration profiles and kinetics of the process. The simulated results were supported by experimental results obtained by a comprehensive heart-cut multidimensional GC (H/C MDGC) approach which was developed to clearly investigate isomerisation of E/Z oxime molecules in both 1D and 2D separations under different isothermal conditions. The carrier gas flow and oven temperature were selected according to initial results for 1D interconversion on a poly(ethyleneglycol) stationary phase, which was further used in both 1D and 2D separations to result in broad zones of oxime interconversion in both dimensions. The method involved repetitive injections of oxime sample, then sampling contiguous fractions of sample into a long 2D column which is intended to promote considerable interconversion. Comprehensiveness arises from the fact that the whole sample is sampled from the 1D to the 2D column, with the long 2D column replacing the short 2D column used in classical comprehensive two-dimensional gas chromatography, where the latter will not promote sufficient interconversion. Data processing and presentation permits a 'rectangular' distribution corresponding to the separated compounds, characteristic of this experiment.
    Matched MeSH terms: Chromatography, Gas/methods*
  10. Fulltext A highly sensitive LC-MS/MS method for quantitative determination of 7 vitamin D metabolites in mouse brain tissue
    Stephenson AJ, Hunter B, Shaw PN, Kassim NSA, Trengove R, Takechi R, et al.
    Anal Bioanal Chem, 2023 Mar;415(7):1357-1369.
    PMID: 36705732 DOI: 10.1007/s00216-023-04527-8
    Despite its critical role in neurodevelopment and brain function, vitamin D (vit-D) homeostasis, metabolism, and kinetics within the central nervous system remain largely undetermined. Thus, it is of critical importance to establish an accurate, highly sensitive, and reproducible method to quantitate vit-D in brain tissue. Here, we present a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method and for the first time, demonstrate detection of seven major vit-D metabolites in brain tissues of C57BL/6J wild-type mice, namely 1,25(OH)2D3, 3-epi-1,25(OH)2D3, 1,25(OH)2D2, 25(OH)D3, 25(OH)D2, 24,25(OH)2D3, and 24,25(OH)2D2. Chromatographic separation was achieved on a pentaflurophenyl column with 3 mM ammonium formate water/methanol [A] and 3 mM ammonium formate methanol/isopropanol [B] mobile phase components. Detection was by positive ion electrospray tandem mass spectrometry with the EVOQ elite triple quadrupole mass spectrometer with an Advance ultra-high-performance liquid chromatograph and online extraction system. Calibration standards of each metabolite prepared in brain matrices were used to validate the detection range, precision, accuracy, and recovery. Isotopically labelled analogues, 1,25(OH)2D3-d3, 25(OH)D3-c5, and 24,25(OH)2D3-d6, served as the internal standards for the closest molecular-related metabolite in all measurements. Standards between 1 fg/mL and 10 ng/mL were injected with a resulting linear range between 0.001 and 1 ng, with an LLOD and LLOQ of 1 pg/mL and 12.5 pg/mL, respectively. The intra-/inter-day precision and accuracy for measuring brain vit-D metabolites ranged between 0.12-11.53% and 0.28-9.11%, respectively. Recovery in acetonitrile ranged between 99.09 and 106.92% for all metabolites. Collectively, the sensitivity and efficiency of our method supersedes previously reported protocols used to measure vit-D and to our knowledge, the first protocol to reveal the abundance of 25(OH)D2, 1,25(OH)D2, and 24,25(OH)2D2, in brain tissue of any species. This technique may be important in supporting the future advancement of pre-clinical research into the function of vit-D in neurophysiological and neuropsychiatric disorders, and neurodegeneration.
    Matched MeSH terms: Chromatography, Liquid/methods
  11. Fulltext Fast and Sensitive HPLC-ESI-MS/MS Method for Etoricoxib Quantification in Human Plasma and Application to Bioequivalence Study
    Loh GOK, Wong EYL, Tan YTF, Heng SC, Saaid M, Cheah KY, et al.
    Molecules, 2022 Sep 04;27(17).
    PMID: 36080473 DOI: 10.3390/molecules27175706
    Etoricoxib is a non-steroidal anti-inflammatory drug (NSAID) used to treat pain and inflammation. The objective of the current study was to develop a sensitive, fast and high-throughput HPLC-ESI-MS/MS method to measure etoricoxib levels in human plasma using a one-step methanol protein precipitation technique. A tandem mass spectrometer equipped with an electrospray ionization (ESI) source operated in a positive mode and multiple reaction monitoring (MRM) were used for data collection. The quantitative MRM transition ions were m/z 359.15 > 279.10 and m/z 363.10 > 282.10 for etoricoxib and IS. The linear range was from 10.00 to 4000.39 ng/mL and the validation parameters were within the acceptance limits of the European Medicine Agency (EMA) and Food and Drug Analysis (FDA) guidelines. The present method was sensitive (10.00 ng/mL with S/N > 40), simple, selective (K prime > 2), and fast (short run time of 2 min), with negligible matrix effect and consistent recovery, suitable for high throughput analysis. The method was used to quantitate etoricoxib plasma concentrations in a bioequivalence study of two 120 mg etoricoxib formulations. Incurred sample reanalysis results further supported that the method was robust and reproducible.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  12. Supercritical fluid extraction of four aromatic herbs and assessment of the volatile compositions, bioactive compounds, antibacterial, and anti-biofilm activity
    Al-Maqtari QA, Al-Ansi W, Mahdi AA, Al-Gheethi AAS, Mushtaq BS, Al-Adeeb A, et al.
    Environ Sci Pollut Res Int, 2021 May;28(20):25479-25492.
    PMID: 33462691 DOI: 10.1007/s11356-021-12346-6
    Artemisia arborescens, Artemisia abyssinica, Pulicaria jaubertii, and Pulicaria petiolaris are fragrant herbs traditionally used in medication and as a food seasoning. To date, there are no studies on the use of supercritical fluids extraction with carbon dioxide (SFE-CO2) on these plants. This study evaluates and compares total phenolic content (TPC), antioxidant activity by DPPH• and ABTS•+, antibacterial, and anti-biofilm activities of SFE-CO2 extracts. Extraction was done by SFE-CO2 with 10% ethanol as a co-solvent. A. abyssinica extract had the highest extraction yield (8.9% ± 0.41). The GC/MS analysis of volatile compounds identified 307, 265, 213, and 201compounds in A. abyssinica, A. arborescens, P. jaubertii, and P. petiolaris, respectively. The P. jaubertii extract had the highest TPC (662.46 ± 50.93 mg gallic acid equivalent/g dry extract), antioxidant activity (58.98% ± 0.20), and antioxidant capacity (71.78 ± 1.84 mg Trolox equivalent/g dry extract). The A. abyssinica and P. jaubertii extracts had significantly higher antimicrobial activity and were more effective against Gram-positive bacteria. B. subtilis was the most sensitive bacterium. P. aeruginosa was the most resistant bacterium. P. jaubertii extract had the optimum MIC and MBC (0.4 mg/ml) against B. subtilis. All SFE-CO2 extracts were effective as an anti-biofilm formation for all tested bacteria at 1/2 MIC. Meanwhile, P. jaubertii and P. petiolaris extracts were effective anti-biofilm for most tested bacteria at 1/16 MIC. Overall, the results indicated that the SFE-CO2 extracts of these plants are good sources of TPC, antioxidants, and antibacterial, and they have promising applications in the industrial fields.
    Matched MeSH terms: Chromatography, Supercritical Fluid*
  13. Glutathione conjugation of nitrogen mustards: In vitro study
    Hamzah N, Kjellberg M, Vanninen P
    Rapid Commun Mass Spectrom, 2023 May 15;37(9):e9495.
    PMID: 36799074 DOI: 10.1002/rcm.9495
    RATIONALE: This paper describes an in vitro study designed to identify metabolic biomarkers resulting from the conjugation of nitrogen mustards (NMs) with glutathione (GSH). The method developed is essential in providing evidence in the event of NM exposure in biomedical samples.

    METHODS: The mass spectral characterization of the proposed NMs-GSH conjugates was performed with liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). The final reaction mixtures were analysed in positive electrospray ionisation (ESI) at different incubation times.

    RESULTS: This study identified three types of conjugates in addition to ethanolamines, the hydrolysis products of NMs. Monoglutathionyl, diglutathionyl and phosphorylated conjugates were produced for each of the NMs, bis(2-chloroethyl)ethylamine (HN1), bis(2-chloroethyl)methylamine (HN2) and tris(2-chloroethyl)amine (HN3). The monoglutathionyl conjugates consisted of HN1-GSH, HN2-GSH and HN3-GSH. The spontaneous and primary conjugates of diglutathionyl were HN1-GSH2, HN2-GSH2 and HN3-GSH2. These included phosphorylated conjugates, namely HN1-GSH-PO4 , HN2-GSH-PO4 and HN3-GSH-PO4 , as might have formed due to hydrolysis in phosphate buffer.

    CONCLUSIONS: The mass spectral data of all conjugates formed in the presence of all NMs and GSH are reported in this study. These GSH metabolites can be used to confirm NMs toxicity in biological samples such as urine.

    Matched MeSH terms: Chromatography, Liquid/methods
  14. LC-MS profiling-based non-targeted secondary metabolite screening for deciphering cosmeceutical potential of Malaysian algae
    Lim MW, Yow YY, Gew LT
    J Cosmet Dermatol, 2023 Oct;22(10):2810-2815.
    PMID: 37313630 DOI: 10.1111/jocd.15794
    BACKGROUND: Application of natural resources from the marine environment in the cosmeceutical industry is gaining great attention.

    AIM: This study pursues to discover the cosmeceutical potential of two Malaysian algae, Sargassum sp. and Kappaphycus sp. by determining their antioxidant capacity and assessing the presence of their secondary metabolites with cosmeceutical potential using non-targeted metabolite profiling.

    METHODS: Metabolite profiling using Quadrupole Time-of-Flight (Q-TOF) liquid chromatography-mass spectrometry (LC-MS) in the Electrospray Ionization (ESI) mode resulted in 110 putative metabolites in Sargassum sp. and 47 putative metabolites in Kappaphycus sp. and were grouped according to their functions. To the best of our knowledge, the bioactive compounds of both algae have not been studied in any great detail. This is the first report to explore their cosmeceutical potential.

    RESULTS: Six antioxidants were detected in Sargassum sp., including fucoxanthin, (3S, 4R, 3'R)-4-Hydroxyalloxanthin, enzacamene N-stearoyl valine, 2-hydroxy-hexadecanoic acid, and metalloporphyrins. Meanwhile, three antioxidants detected in Kappahycus sp., namely Tanacetol A, 2-fluoro palmitic acid and idebenone metabolites. Three antioxidants are found in both algae species, namely, 3-tert-Butyl-5-methylcatechol, (-)-isoamijiol, and (6S)-dehydrovomifoliol. Anti-inflammatory metabolites such as 5(R)-HETE, protoverine, phytosphingosine, 4,5-Leukotriene-A4, and 5Z-octadecenoic acid were also found in both species. Sargassum sp. possesses higher antioxidant capacity as compared to Kappahycus sp. which may be linked to its number of antioxidant compounds found through LC-MS.

    CONCLUSIONS: Hence, our results conclude that Malaysian Sargassum sp. and Kappaphycus sp. are potential natural cosmeceutical ingredients as we aim to produce algae cosmeceutical products using native algae.

    Matched MeSH terms: Chromatography, Liquid/methods
  15. Development and validation of a gradient HPLC-UV method for mitragynine following in vitro skin permeation studies
    Sim YS, Chong ZY, Azizi J, Goh CF
    J Chromatogr B Analyt Technol Biomed Life Sci, 2022 Jul 15;1204:123316.
    PMID: 35700649 DOI: 10.1016/j.jchromb.2022.123316
    Mitragynine is a promising candidate for pain relief and opiate replacement but the investigations for drug delivery are lacking. This study aims to investigate the potential of mitragynine to be delivered through the skin with an emphasis on developing and validating a gradient HPLC-UV analytical method to determine mitragynine in the samples collected during in vitro skin permeation studies. The optimised method involves a gradient elution using a C18 column with a mobile phase comprising acetonitrile and 0.1 %v/v of formic acid (0-1 min: 30:70 to 70:30 (v/v) and hold up to 4 min; 4-6 min: return to 30:70 (v/v) and hold up to 10 min) at a flow rate of 1.2 mL/min. This method was validated based on the standards set by the International Council on Harmonisation guidelines. The method showed mitragynine elution at ∼ 4 min with adequate linearity (R2 ≥ 0.999 for concentration ranges of 0.5-10 and 10-175 μg/mL) and acceptable limits of detection and quantification at 0.47 and 1.43 μg/mL, respectively. The analytical performance is robust with excellent precision and accuracy. This method was used to evaluate the in vitro skin permeation of mitragynine (5 %w/v) from simple solvent systems over 48 hr. The results showed a cumulative amount of mitragynine permeated at ∼ 11 μg/cm2 for dimethyl sulfoxide and ∼ 4 μg/cm2 for propylene glycol. The study not only addressed the issues of the currently available HPLC-UV methods that limit the direct application but also affirmed the potential of mitragynine to be delivered through the skin.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods
  16. Fulltext The Effects of Different Extraction Methods on Antioxidant Properties, Chemical Composition, and Thermal Behavior of Black Seed (Nigella sativa L.) Oil
    Mohammed NK, Abd Manap MY, Tan CP, Muhialdin BJ, Alhelli AM, Meor Hussin AS
    Evid Based Complement Alternat Med, 2016;2016:6273817.
    PMID: 27642353 DOI: 10.1155/2016/6273817
    The Nigella sativa L. popularly referred to as black seeds are widely used as a form of traditional nutrition and medicine. N. sativa seeds were used for the extraction of their oil by way of supercritical fluid extraction (SFE) and cold press (CP) to determine the physicochemical properties, antioxidant activity, and thermal behavior. The GC-MS results showed the primary constituents in the Nigella sativa oil (NSO) were Caryophyllene (17.47%) followed by thymoquinone (TQ) (11.80%), 1,4-Cyclohexadiene (7.17%), longifolene (3.5%), and carvacrol (1.82%). The concentration of TQ was found to be 6.63 mg/mL for oil extracted using SFE and 1.56 mg/mL for oil extracted by CP method. The antioxidant activity measured by DPPH and the IC50 was 1.58 mg/mL and 2.30 mg/mL for SFE oil and cold pressed oil, respectively. The ferric reducing/antioxidant power (FRAP) activity for SFE oil and CP oil was 538.67 mmol/100 mL and 329.00 mmol/100 mL, respectively. The total phenolic content (TPC) of SFE oil was 160.51 mg/100 mL and 94.40 mg/100 mL for CP oil presented as gallic acid equivalents (GAE). This research showed that a high level of natural antioxidants could be derived from NSO extracted by SFE.
    Matched MeSH terms: Gas Chromatography-Mass Spectrometry; Chromatography, Supercritical Fluid
  17. Investigation of interaction studies of cefpirome with ACE-inhibitors in various buffers
    Nawaz M, Arayne MS, Sultana N, Abbas HF
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Feb 25;137:1050-4.
    PMID: 25300038 DOI: 10.1016/j.saa.2014.08.152
    This work describes a RP-HPLC method for the determination and interaction studies of cefpirome with ACE-inhibitors (captopril, enalapril and lisinopril) in various buffers. The separation and interaction of cefpirome with ACE-inhibitors was achieved on a Purospher Star, C18 (5 μm, 250×4.6 mm) column. Mobile phase consisted of methanol: water (80:20, v/v, pH 3.3); however, for the separation of lisinopril, it was modified to methanol-water (40:60, v/v, pH 3.3) and pumped at a flow rate of 1 mL min(-1). In all cases, UV detection was performed at 225 nm. Interactions were carried out in physiological pH i.e., pH 1 (simulated gastric juice), 4 (simulated full stomach), 7.4 (blood pH) and 9 (simulated GI), drug contents were analyzed by reverse phase high performance liquid chromatography. Method was found linear in the concentration range of 1.0-50.0 μg mL(-1) with correlation coefficient (r(2)) of 0.999. Precision (RSD%) was less than 2.0%, indicating good precision of the method and accuracy was 98.0-100.0%. Furthermore, cefpirome-ACE-inhibitors' complexes were also synthesized and results were elucidated on the basis of FT-IR, and (1)H NMR. The interaction results show that these interactions are pH dependent and for the co-administration of cefpirome and ACE-inhibitors, a proper interval should be given.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods; Chromatography, Reverse-Phase/methods
  18. Validation of a reverse-phase high-performance liquid chromatography method for the determination of amino acids in gelatins by application of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate reagent
    Azilawati MI, Hashim DM, Jamilah B, Amin I
    J Chromatogr A, 2014 Aug 1;1353:49-56.
    PMID: 24797394 DOI: 10.1016/j.chroma.2014.04.050
    In-house method validation was conducted to determine amino acid composition in gelatin by a pre-column derivatization procedure with the 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate reagent. The analytical parameters revealed that the validated method was capable of selectively performing a good chromatographic separation for 18 amino acids in less than 40 min; the overall detection and quantitation limit for amino acids fell into ranges of 5.68-12.48 and 36.0-39.0 pmol/μl, respectively; the matrix effect was not observed, and the linearity range was 37.5-1000 pmol/μl. The accuracy (precision and recovery) analyses of the method were conducted under repeatable conditions on different days in random order. Method precision revealed by HorRat values was significantly less than 2, except for histidine with a precision of 2.19, and the method recoveries had a range of 80-115% except for alanine which was recovered at 79.4%. The findings were reproducible and accurately defined, and the method was found to be suited to routine analysis of amino acid composition in gelatin-based ingredients.
    Matched MeSH terms: Chromatography, High Pressure Liquid/methods*; Chromatography, Reverse-Phase/methods*
  19. Application of supercritical fluid chromatography in the quantitative analysis of minor components (carotenes, vitamin E, sterols, and squalene) from palm oil
    Choo YM, Ng MH, Ma AN, Chuah CH, Hashim MA
    Lipids, 2005 Apr;40(4):429-32.
    PMID: 16028723
    The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in palm oil were also isolated into their respective components, alpha-tocopherol, alpha-tocotrienol, gamma-tocopherol, gamma-tocotrienol, and delta-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was carried out and was found to be comparable to those analyzed by other established analytical methods.
    Matched MeSH terms: Chromatography, Gas; Chromatography, High Pressure Liquid; Chromatography, Supercritical Fluid*
  20. A new oxolane from Enterobacter cloacae
    Yap AC, Chan KG, Sim KS, Choo YM
    Nat Prod Res, 2016 Apr;30(7):783-8.
    PMID: 26252083 DOI: 10.1080/14786419.2015.1065492
    Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.
    Matched MeSH terms: Chromatography
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