Displaying publications 81 - 100 of 337 in total

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  1. RP-HPLC analytical method development and optimization for quantification of donepezil hydrochloride in orally disintegrating tablet
    Liew KB, Peh KK, Fung Tan YT
    Pak J Pharm Sci, 2013 Sep;26(5):961-6.
    PMID: 24035953
    An easy, fast and validated RV-HPLC method was invented to quantify donepezil hydrochloride in drug solution and orally disintegrating tablet. The separation was carried out using reversed phase C-18 column (Agilent Eclipse Plus C-18) with UV detection at 268 nm. Method optimization was tested using various composition of organic solvent. The mobile phase comprised of phosphate buffer (0.01M), methanol and acetonitrile (50:30:20, v/v) adjusted to pH 2.7 with phosphoric acid (80%) was found as the optimum mobile phase. The method showed intraday precision and accuracy in the range of 0.24% to -1.83% and -1.83% to 1.99% respectively, while interday precision and accuracy ranged between 1.41% to 1.81% and 0.11% to 1.90% respectively. The standard calibration curve was linear from 0.125 μg/mL to 16 μg/mL, with correlation coefficient of 0.9997±0.00016. The drug solution was stable under room temperature at least for 6 hours. System suitability studies were done. The average plate count was > 2000, tailing factor <1, and capacity factor of 3.30. The retention time was 5.6 min. The HPLC method was used to assay donepezil hydrochloride in tablet and dissolution study of in-house manufactured donepezil orally disintegrating tablet and original Aricept.
    Matched MeSH terms: Limit of Detection
  2. Quantitative HPLC analysis of gallic acid in benincasa hispida prepared with different extraction techniques
    Fatariah Z, Zulkhairuazha TT, Wan Rosli W
    Sains Malaysiana, 2014;43:1181-1187.
    Ash gourd (Benincasa hispida, Bh) is traditionally claimed useful in treating asthma, cough, diabetes, haemoptysis and hemorrhages from internal organs, epilepsy, fever and balancing of the body heat. One of the major phenolic acids presented in Benincasa hispida is gallic acid, a phenolic compound which is linked with its ability in reducing Type II diabetes. The aim of the present study was to investigate the effect of different extraction techniques on the concentration of gallic acid in Bh. The Bh extracts were prepared with three different techniques namely; fresh extract (FE), low heating (LH) and drying and heating (DH). The gallic acid has been detected and quantified using high performance liquid chromatography (HPLC) coupled with uv-Vis detector. The amount of gallic acid detected in FE, LH and DH were 0.036, 0.050 and 0 272 mg1100 g, respectively. The limits of detection was 0.75 liglmL while the limit of quantification and recovery were 2.50 liglmL and 95 .53% , respectively. In summary, HPLC technique coupled with vv detector systems able to quantify gallic acid in Bh extracts. The gallic acid were present at higher concentration in Bh extracted using drying and heating, followed by low heating and fresh extract methods.
    Matched MeSH terms: Limit of Detection
  3. Quantitation of methadone and metabolite in patients under maintenance treatment
    Diong SH, Mohd Yusoff NS, Sim MS, Raja Aziddin RE, Chik Z, Rajan P, et al.
    J Anal Toxicol, 2014 Nov-Dec;38(9):660-6.
    PMID: 25106416 DOI: 10.1093/jat/bku096
    Gas chromatography-mass spectrometry quantitative method was developed to monitor concentrations of methadone and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) in plasma and urine of patients. The developed method was simple, accurate and reproducible to quantify methadone and EDDP in plasma and urine samples in the concentration range of 15-1,000 and 50-2,000 ng/mL, respectively. The proposed analytical method was applied to plasma and urine samples obtained from 96 patients undergoing methadone maintenance treatment (MMT) with daily methadone doses of 2-120 mg/day. Urinary methadone excretion was observed to be significantly affected by pH, in which the ratio of methadone to EDDP was two times higher in acidic urine (P = 0.029). The findings of this study further enhance the guidelines for monitoring of methadone treatment among outpatients. Methadone-to-EDDP ratio in urine was found to be consistent at 24 and 4 h, hence suggesting the possibility that outpatients may be monitored with single urine sample in order to check for compliance. This study which provides data on peak concentrations of methadone and EDDP as well as the ratio of both compounds has added to the body of knowledge regarding pharmacokinetic properties of methadone among heroin-dependent patients under MMT.
    Study site: University Malaya Medical Centre (UMMC), HKL, University Malaya Centre for Addiction Sciences (UMCAS) and Rehabilitation Centre of Al-Rahman Mosque, Kuala Lumpur, Malaysia
    Matched MeSH terms: Limit of Detection
  4. Quantification of nimetazepam and its metabolite in human hair samples using liquid chromatography-tandem mass spectrometry: Case report
    Dai Y, Han L, Wang Y, Zhao K, Gu J, Bai H, et al.
    Leg Med (Tokyo), 2023 Nov;65:102303.
    PMID: 37598646 DOI: 10.1016/j.legalmed.2023.102303
    Nimetazepam (marketed brand names; Erimin and Lavol) is an intermediate acting benzodiazepine derivative, which was widely used mainly in East and Southeast Asian region countries including Japan, Malaysia, Brunei, the Philippines, Thailand, Indonesia, Hong Kong, Singapore and China. Nimetazepam and its metabolite 7-aminonimetazepam were quantified from human hair samples by liquid chromatography tandem-mass spectrometry (LC-MS/MS), under selective reaction monitoring mode. Using diazepam-d5 as an internal standard, the concentration of nimetazepam and its metabolite 7-aminonimetazepam could be determined by matrix matched calibration method. Extraction of the target compounds was performed by using methanol, followed by evaporation and being concentrated with nitrogen. The Limit of quantification concentrations of nimetazepam and its metabolite 7-aminonimetazepam in hair samples were both 25 pg/mg by established method. The concentrations of nimetazepam in hair samples obtained from 2 users were 27.4, and 22.0 pg/mg, respectively; the concentrations of 7-animonimetazepam in hair samples were 54.2 and 29.1 pg/mg, respectively. In our study, the 7-aminonimetazepam concentrations in hair was higher than those of nimetazepam in the authentic hair samples. To our knowledge, this is the first report to establish the detailed procedure for quantificating nimetazepam and 7-aminonimetazepam in human hair by LC-MS/MS.
    Matched MeSH terms: Limit of Detection
  5. Fulltext Quantification of cortisol for the medical diagnosis of multiple pregnancy-related diseases
    Zhang J, Gopinath SCB
    3 Biotech, 2020 Feb;10(2):35.
    PMID: 31988829 DOI: 10.1007/s13205-019-2030-z
    Cortisol is a stress hormone released from the adrenal glands and is responsible for both hyperglycemia and hypertension during pregnancy. These factors make it mandatory to detect the levels of cortisol during pregnancy to identify and treat hypoglycemia and hypertension. In this study, cortisol levels were quantified with an aptamer-conjugated gold nanorod using an electrochemical interdigitated electrode sensor. The surface uniformity was analyzed by high-power microscopy and 3D-nanoprofiler imaging. The detection limit was determined to be 0.01 ng/mL, and a linear regression indicated that the sensitivity range was in the range of 0.01-0.1 ng/mL, based on a 3σ calculation. Moreover, the specificity of the aptamer was determined by a binding analysis against norepinephrine and progesterone, and it was clearly found that the aptamer specifically recognizes only cortisol. Further, the presence of cortisol was detected in the serum in a dose-dependent manner. This method is useful to detect and correlate multiple pregnancy-related diseases by quantifying the levels of cortisol.
    Matched MeSH terms: Limit of Detection
  6. Quality by Design-based RP-HPLC Method for Estimation of Curcumin in Rat Plasma and Fecal Microbiota Extract-based Solid Self-nano Emulsifying Drug Delivery System
    Corrie L, Gulati M, Kaur J, Awasthi A, Vishwas S, Ramanunny AK, et al.
    Curr Drug Res Rev, 2023;15(3):272-285.
    PMID: 36683365 DOI: 10.2174/2589977515666230120140543
    BACKGROUND: Curcumin (CRM) is known to possess various therapeutic properties, such as anti-inflammatory and antidiabetic properties, and is, therefore, considered to be an effective therapeutic.

    OBJECTIVE: A sensitive method for the estimation of CRM in plasma, as well as fecal matter-based solid self-nano emulsifying drug delivery system (S-SNEDDS), has been reported for the first time.

    METHODS: A bioanalytical method was optimized using Box-Behnken Design having 13 runs and 3 responses. The optimized method was developed using methanol and water (70:30 v/v) with a flow rate of 1 mL/min. Quercetin was used as an internal standard. A specificity test was also performed for the developed CRM solid self-nano emulsifying drug delivery system.

    RESULTS: The retention time of CRM was found to be 14.18 minutes. The developed method was validated and found to be linear in the range of 50-250 ng/mL with an R2 of 0.999. Accuracy studies indicated that CRM had a percentage recovery of less than 105% and more than 95%, respectively. Precision studies were carried out for inter, intraday, and inter-analyst precision, and the %RSD was found to be less than 2%. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 3.37 ng/mL and 10.23 ng/mL, respectively. Stability studies for shortterm, long term and freeze-thaw cycles showed a %RSD of less than 2%, indicating the stability of CRM in the plasma matrix. Moreover, the blank fecal microbiota extract slurry did not show any peak at the retention time of CRM in a CRM-loaded solid nanoemulsifying drug delivery system containing fecal microbiota extract indicating its specificity.

    CONCLUSION: Hence, the developed method can have clinical implications as it helps estimate CRM in blood samples and also provides a simple and sensitive method for the estimation of plant-based flavonoids along with fecal microbiota extract formulations.

    Matched MeSH terms: Limit of Detection
  7. Pyrazinium thioacetate capped gold nanoparticles as Fe(III) sensor and Fe(III) marked anti-proliferating agent in human neuroblastoma cells
    Anwar A, Minhaz A, Hussain SS, Anwar A, Simjee SU, Ishaq M, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2019 Jan 05;206:135-140.
    PMID: 30096697 DOI: 10.1016/j.saa.2018.07.099
    Gold nanoparticles (AuNPs) stabilized by new cationic 1‑(3‑(acetylthio)propyl)pyrazin‑1‑ium ligand (PPTA) were synthesized. AuNPs stabilized by PPTA (PPTA-AuNPs) were found to be spherical and polydispersed with the average size of 60 nm. Human neuroblastoma (SHSY-5Y) cells permeability of PPTA-AuNPs was found to be a key feature to study the intracellular quenching of Fe(III) proliferative activity. In vitro MTT assay revealed non-cytotoxicity of PPTA and PPTA-AuNPs at 100 μM concentration, while treatment of 100 μM of Fe(III) with SHSY-5Y cells resulted into higher cells viability. Contrary, a mixture of 1:1 Fe(III) with PPTA-AuNPs showed no change in the viability of cells at same concentration which suggests the intracellular complexation and recognition of Fe(III) by PPTA-AuNPs. AFM morphological analysis of SHSY-5Y cells also supported the MTT assay results, and it is safe to conclude that PPTA-AuNPs can be used as Fe(III) probes in living cells. In addition, Fe(III) caused a significant decrease in the absorbance of surface plasmon resonance (SPR) band of PPTA-AuNPs in a wide range of concentration and pH, with limit of detection 4.3 μM. Moreover, the specific response of PPTA-AuNPs towards Fe(III) was unaffected by the interference of other metals and components of real samples of tap water.
    Matched MeSH terms: Limit of Detection
  8. Proline-Modified UIO-66 as Nanocarriers to Enhance Candida rugosa Lipase Catalytic Activity and Stability for Electrochemical Detection of Nitrofen
    Cheng Y, Lai OM, Tan CP, Panpipat W, Cheong LZ, Shen C
    ACS Appl Mater Interfaces, 2021 Jan 27;13(3):4146-4155.
    PMID: 33440928 DOI: 10.1021/acsami.0c17134
    Immobilization can be used to improve the stability of lipases and enhances lipase recovery and reusability, which increases its commercial value and industrial applications. Nevertheless, immobilization frequently causes conformational changes of the lipases, which decrease lipase catalytic activity. in the present work, we synthesized UIO-66 and grafted UIO-66 crystals with proline for immobilization of Candida rugosa lipase (CRL). As indicated by steady-state fluorescence microscopy, grafting of proline onto UIO-66 crystals induced beneficial conformational change in CRL. CRL immobilized on UIO-66/Pro (CRL@UIO-66/Pro) demonstrated higher enzyme activity and better recyclability than that immobilized on UIO-66 (CRL@UIO-66) in both hydrolysis (CRL@UIO-66/Pro: 0.34 U; CRL@UIO-66: 0.15 U) and transesterification (CRL@UIO-66/Pro: 0.93 U; CRL@UIO-66: 0.25 U) reactions. The higher values of kcat and kcat/Km of CRL@UIO-66/Pro also showed that it had better catalytic efficiency as compared to CRL@UIO-66. It is also worth noting that CRL@UIO-66/Pro (0.93 U) demonstrated a much higher transesterification activity as compared to free CRL (0.11 U), indicating that UIO-66/Pro has increased the solvent stability of CRL. Both CRL@UIO-66 and CRL@UIO-66/Pro were also used for the fabrication of biosensors for nitrofen with a wide linear range (0-100 μM), lower limit of detection, and good recovery rate.
    Matched MeSH terms: Limit of Detection
  9. Portable electrochemical immunosensor for detection of Mycobacterium tuberculosis secreted protein CFP10-ESAT6 in clinical sputum samples
    Mohd Azmi UZ, Yusof NA, Abdullah J, Alang Ahmad SA, Mohd Faudzi FN, Ahmad Raston NH, et al.
    Mikrochim Acta, 2021 01 06;188(1):20.
    PMID: 33404779 DOI: 10.1007/s00604-020-04669-x
    An early detection of Mycobacterium tuberculosis is very important to reduce the number of fatal cases and allow for fast recovery. However, the interpretation of the result from smear microscopy requires skilled personnel due to the propensity of the method to produce false-negative results. In this work, a portable, rapid, and simple sandwich-type immunosensor reader has been developed that is able to detect the presence of M. tuberculosis in sputum samples. By using sandwich-type immunosensor, an anti-CFP10-ESAT6 antibody was immobilized onto the graphene/polyaniline (GP/PANI)-modified gold screen-printed electrode. After incubation with the target CFP10-ESAT6 antigen, the iron/gold magnetic nanoparticles (Fe3O4/Au MNPs) conjugated with anti-CFP10-ESAT6 antibody were used to complete the sandwich format. Differential pulse voltammetry (DPV) technique was used to detect the CFP10-ESAT6 antigen at the potential range of 0.0-1.0 V. The detection time is less than 2 h. Under optimal condition, CFP10-ESAT6 antigen was detected in a linear range from 10 to 500 ng mL-1 with a limit of detection at 1.5 ng mL-1. The method developed from this process was then integrated into a portable reader. The performance of the sensor was investigated and compared with the standard methods (culture and smear microscopy). It provides a good correlation (100% sensitivity and 91.7% specificity) with both methods of detection for M. tuberculosis in sputum samples henceforth, demonstrating the potential of the device as a more practical screening tool.Graphical abstract.
    Matched MeSH terms: Limit of Detection
  10. Polysilicon nanogap lab-on-chip facilitates multiplex analyses with single analyte
    Balakrishnan SR, Hashim U, Gopinath SC, Poopalan P, Ramayya HR, Veeradasan P, et al.
    Biosens Bioelectron, 2016 Oct 15;84:44-52.
    PMID: 26560969 DOI: 10.1016/j.bios.2015.10.075
    Rationally designed biosensing system supports multiplex analyses is warranted for medical diagnosis to determine the level of analyte interaction. The chemically functionalized novel multi-electrode polysilicon nanogap (PSNG) lab-on-chip is designed in this study, facilitates multiplex analyses for a single analyte. On the fabricated 69nm PSNG, biocompatibility and structural characteristics were verified for the efficient binding of Human Chorionic Gonadotropin (hCG). With the assistance of microfluidics, hCG sample was delivered via single-injection to 3-Aminopropyl(triethoxy)silane (APTES) and Glycidoxypropyl(trimethoxy)silane (GPMS) modified PSNG electrodes and the transduced signal was used to investigate the dielectric mechanisms for multiplex analyses. The results from amperometric response and impedance measurement delivered the scale of interaction between anti-hCG antibody and hCG that exhibited 6.5 times higher sensitivity for the chemical linker, APTES than GPMS. Under optimized experimental conditions, APTES and GPMS modified immunosensor has a limit of detection as 0.56mIU/ml and 2.93mIU/ml (at S/N=3), with dissociation constants (Kd) of 5.65±2.5mIU/ml and 7.28±2.6mIU/ml, respectively. These results suggest that multiplex analysis of single target could enhance the accuracy of detection and reliable for real-time comparative analyses. The designed PSNG is simple, feasible, requires low sample consumption and could be applied for any given multiplex analyses.
    Matched MeSH terms: Limit of Detection
  11. Polypyrrole-magnetite dispersive micro-solid-phase extraction combined with ultraviolet-visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater
    Kamaruddin AF, Sanagi MM, Wan Ibrahim WA, Md Shukri DS, Abdul Keyon AS
    J Sep Sci, 2017 Nov;40(21):4256-4263.
    PMID: 28851082 DOI: 10.1002/jssc.201700659
    Polypyrrole-magnetite dispersive micro-solid-phase extraction method combined with ultraviolet-visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole-magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro-solid-phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole-magnetite dispersive micro-solid phase-extraction conditions were sample pH 8, 60 mg polypyrrole-magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole-magnetite dispersive micro-solid-phase extraction with ultraviolet-visible method showed good linearity in the range of 0.05-7 mg/L (R2  > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4-111.3%) with relative standard deviations 
    Matched MeSH terms: Limit of Detection
  12. Polychlorinated biphenyl contamination of paints containing polycyclic- and Naphthol AS-type pigments
    Anezaki K, Kannan N, Nakano T
    Environ Sci Pollut Res Int, 2015 Oct;22(19):14478-88.
    PMID: 24809497 DOI: 10.1007/s11356-014-2985-6
    This study reports the concentrations and congener partners of polychlorinated biphenyls (PCBs) in commercially available paints. Polycyclic-type pigments containing dioxazine violet (pigment violet (PV) 23, PV37) and diketopyrrolopyrrole (PR254, PR255) were found to contain PCB-56, PCB-77, PCB-40, PCB-5, and PCB-12, and PCB-6, PCB-13, and PCB-15, respectively, as major congeners. Dioxazine violet is contaminated with by-products during synthesis from o-dichlorobenzene, which is used as a solvent during synthesis, and diketopyrrolopyrrole is contaminated with by-products during synthesis from p-chlorobenzonitrile. The concentration of PCBs in paint containing PV23 or PV37 was 0.050-29 mg/kg, and toxic equivalency (TEQ) values ranged 1.1-160 pg-TEQ/g. The concentration of PCBs in paint containing PR254 or PR255 was 0.0019-2.4 mg/kg. Naphthol AS is an azo-type pigment, and PCB-52 was detected in paint containing pigment red (PR) 9 with 2,5-dichloroaniline as its source. PCB-146, PCB-149, and PCB-153 were identified from paint containing PR112 produced from 2,4,5-trichloroaniline, as major congeners. These congeners have chlorine positions similar to aniline, indicating that these congeners are by-products obtained during the synthesis of pigments. The concentrations of PCBs in paints containing PR9 and PR112 were 0.0042-0.43 and 0.0044-3.8 mg/kg, respectively. The corresponding TEQ for PR112 was 0.0039-8.6 pg-TEQ/g.
    Matched MeSH terms: Limit of Detection
  13. Polyaniline-dicationic ionic liquid coated with magnetic nanoparticles composite for magnetic solid phase extraction of polycyclic aromatic hydrocarbons in environmental samples
    Shahriman MS, Ramachandran MR, Zain NNM, Mohamad S, Manan NSA, Yaman SM
    Talanta, 2018 Feb 01;178:211-221.
    PMID: 29136814 DOI: 10.1016/j.talanta.2017.09.023
    In this present study, magnetic nanoparticles (MNPs) nanocomposites modified with polyaniline (PANI) coated newly synthesised dicationic ionic liquid (DICAT) forming MNP-PANI-DICAT were successfully synthesised as new generation material for magnetic solid phase extraction (MSPE). MNP-PANI-DICAT was characterised by FT-IR NMR, CHN, BET, SEM, TEM, and VSM techniques and the results were compared with MNP-PANI and native MNP. This new material was applied as a magnetic adsorbent for the pre-concentration and separation of polycyclic aromatic hydrocarbons (PAHs) due to the π-π interaction between polyaniline shell and dicationic ionic liquid (DICAT) with PAHs compounds. Under the optimal conditions, the proposed method was evaluated and applied for the analysis of PAHs in environmental samples using gas chromatography-mass spectrometry (GC-MS). The validation method showed good linearity (0.005-500µgL-1) with the coefficient of determination (R2) > 0.999. The limits of detection (LOD) and quantification (LOQ) of the developed method (MNP-PANI-DICAT-MSPE) were in the range of 0.0008-0.2086µgL-1and 0.0024-0.6320µgL-1, respectively. The enrichment factor (EF) of PAHs on MNP-PANI-DICAT-MSPE were in the range of 7.546-29.632. The extraction recoveries of natural water, sludge, and soil samples were ranged from 80.2% to 111.9% with relative standard deviation (RSD) less than 5.6%. The newly synthesised MNP-PANI-DICAT possess good sensitivity, reusability, and fast extraction of PAHs under the MSPE procedure in various environmental samples.
    Matched MeSH terms: Limit of Detection
  14. Poly-(MMA-IL) filter paper: A new class of paper-based analytical device for thin-film microextraction of multi-class antibiotics in environmental water samples using LC-MS/MS analysis
    Shahriman MS, Mohamad S, Mohamad Zain NN, Raoov M
    Talanta, 2023 Mar 01;254:124188.
    PMID: 36521327 DOI: 10.1016/j.talanta.2022.124188
    A paper-based polymeric ionic liquid (p-Poly-(MMA-IL)) was successfully developed by grafting the polymeric ionic liquid on the surface of commercial filter paper (FP) by using the dipping method, presenting a new cost-effective film. The newly developed p-Poly-(MMA-IL) FP was then applied as a paper-based thin-film microextraction (p-TFME) analytical device to extract 14 compounds as representative of five groups of antibiotic drugs, which were sulfonamides, tetracyclines, fluoroquinolones, penicillin and macrolides in environmental water samples. Besides, p-Poly-(MMA-IL) FP, p-Poly-(MMA) FP, and unmodified filter paper were successfully characterised by FTIR, NMR, FESEM, TGA, and XRD techniques. They underwent significant parameters optimisation, which affected the extraction efficiency. Under optimal conditions, the proposed (p-Poly-(MMA-IL) FP-TFME) device method was evaluated and applied to analyse multi-class antibiotic drugs in environmental water samples by using a liquid chromatography-mass spectrometry (LC-MS). The validation method showed that a good linearity (0.1 μg L-1 - 500 μg L-1) was noted (R2 > 0.993, n = 3). Detection and quantification limits were within 0.05 μg L-1 - 4.52 μg L-1 and 0.15 μg L-1 - 13.6 μg L-1, respectively. The relative standard deviation (RSD) values ranged at 1.4%-12.2% (intra-day, n = 15) and 4.4%-11.0% (inter-day, n = 10). The extraction recoveries of environmental water samples ranged from 79.1% to 126.8%, with an RSD of less than 15.4% (n = 3). The newly developed paper-based polymeric ionic liquid (p-Poly-(MMA-IL) FP) for analysis of multi-class antibiotic drugs under the p-TFME analytical device procedure was successfully achieved with limited sample volume and organic solvent, fast extraction, and feasible in daily analysis. The detection concentration and relative RSD of multi-class antibiotics determined in various environmental water samples by the proposed method (n = 5) were within 0.44 μg L-1 - 54.41 μg L-1 and 0.69%-15.56%, respectively. These results signified the potential of the p-Poly-(MMA-IL) FP-TFME device as an efficient, sensitive and environmentally friendly approach for analysing antibiotics.
    Matched MeSH terms: Limit of Detection
  15. Poly(cyclodextrin-ionic liquid) based ferrofluid: A new class of magnetic colloid for dispersive liquid phase microextraction of polycyclic aromatic hydrocarbons from food samples prior to GC-FID analysis
    Yih Hui B, Mohamad Zain NN, Mohamad S, Varanusupakul P, Osman H, Raoov M
    Food Chem, 2020 Jun 01;314:126214.
    PMID: 31972404 DOI: 10.1016/j.foodchem.2020.126214
    Poly(β-cyclodextrin-ionic liquid) grafted magnetic nanoparticles combined with 1-octanol as supramolecular solvents (SUPRASs) presenting new ferrofluid was developed and successfully applied in the dispersive liquid-phase microextraction of seven representative polycyclic aromatic hydrocarbons. One variable at-a-time (OVAT) analysis and response surface methodology (RSM) were used for efficient optimization of the main variables. The calibration curves were found to be linear in the range of 0.1-150 ng mL-1 with correlation of determinations (R2) ranging from 0.9944 to 0.9986. Detection limits ranged at 0.02-0.07 ng mL-1 for all studied PAHs. The intra and inter-day precision values (RSD %) were in the range of 1.80%-7.56% and 2.97%-8.23%, respectively. The ferrofluid showed a satisfactory reproducibility between 1.72% and 5.90%, and acceptable recovery values at 84%-110% were obtained for the real samples analysis. The optimized method was successfully applied to access the content safety of the PAHs studied in a variety of commercial food and beverages available in Malaysia.
    Matched MeSH terms: Limit of Detection
  16. Fulltext Peptide Cross-Linked Poly (Ethylene Glycol) Hydrogel Films as Biosensor Coatings for the Detection of Collagenase
    Ahmad N, Colak B, Zhang DW, Gibbs MJ, Watkinson M, Becer CR, et al.
    Sensors (Basel), 2019 Apr 08;19(7).
    PMID: 30965649 DOI: 10.3390/s19071677
    Peptide cross-linked poly(ethylene glycol) hydrogel has been widely used for drug delivery and tissue engineering. However, the use of this material as a biosensor for the detection of collagenase has not been explored. Proteases play a key role in the pathology of diseases such as rheumatoid arthritis and osteoarthritis. The detection of this class of enzyme using the degradable hydrogel film format is promising as a point-of-care device for disease monitoring. In this study, a protease biosensor was developed based on the degradation of a peptide cross-linked poly(ethylene glycol) hydrogel film and demonstrated for the detection of collagenase. The hydrogel was deposited on gold-coated quartz crystals, and their degradation in the presence of collagenase was monitored using a quartz crystal microbalance (QCM). The biosensor was shown to respond to concentrations between 2 and 2000 nM in less than 10 min with a lower detection limit of 2 nM.
    Matched MeSH terms: Limit of Detection
  17. PVDF-ErGO-GRC electrode: A single setup electrochemical system for separation, pre-concentration and detection of lead ions in complex aqueous samples
    Hamsawahini K, Sathishkumar P, Ahamad R, Yusoff AR
    Talanta, 2016 Feb 1;148:101-7.
    PMID: 26653429 DOI: 10.1016/j.talanta.2015.10.044
    An effective electrode was developed based on electromembrane extraction (EME) and square wave voltammetry (SWV) for simultaneous separation, pre-concentration and determination of lead (II) (Pb(II)) ions in complex aqueous samples. Electrochemically reduced graphene oxide-graphite reinforced carbon (ErGO-GRC) was utilized in conjunction with the SWV. Pb(II) ions were extracted from an aqueous sample solution into an acidic acceptor phase (1M HCl) in the lumen of the polyvinylidene fluoride (PVDF) membrane bag by the application of voltage of maximum 6 V across the supported liquid membrane (SLM), consisting of organic solvent and di-(2-ethylhexyl)phosphoric acid (D2EHPA). The parameters affecting the EME were optimized for Pb(II) ions. The optimum EME conditions were found to be 20% D2EHPA in 1-octanol impregnated in the wall of PVDF membrane (PVDF17) as the SLM, extraction time of 20 min, pH of sample solution of 8 and a voltage of 5 V. The PVDF-ErGO-GRC electrode system attained enrichment factors of 40 times and 80% of extraction with relative standard deviations (n=5) of 8.3%. Good linearity ranging from 0.25 to 2 nM with coefficients correlation of 0.999 was obtained. The Pb(II) ions detection limit of PVDF-ErGO-GRC electrode was found to be 0.09 nM. The newly developed single setup electrochemical system was applied to complex aqueous samples such as tap, river and sea water to evaluate the feasibility of the method for applications.
    Matched MeSH terms: Limit of Detection
  18. Organophosphorus Pesticide Multiresidues in Commercialized Asian Rice
    Azlan NSM, Wee SY, Ismail NAH, Nasir HM, Aris AZ
    Environ Toxicol Chem, 2020 10;39(10):1908-1917.
    PMID: 32621623 DOI: 10.1002/etc.4813
    The organophosphorus pesticides (OPPs) commonly used in agricultural practices can pose a risk of potential exposure to humans via food consumption. We describe an analytical method for solid-phase extraction coupled with high-performance liquid chromatography-diode array detector (SPE-HPLC-DAD) for the detection of OPPs (quinalphos, diazinon, and chlorpyrifos) in rice grains. The isolation of targeted residues was initiated with double extraction before SPE-HPLC-DAD, crucially reducing matrix interferences and detecting a wide range of multiple residues in rice grains. Coefficients of 0.9968 to 0.9991 showed a strong linearity, with limits of detection and quantification ranging from 0.36 to 0.68 µg/kg and from 1.20 to 2.28 µg/kg, respectively. High recoveries (80.4-110.3%) were observed at 3 spiking levels (50, 100, and 200 µg/kg), indicating good accuracy. The relative standard deviations of all residues (0.19-8.66%) validated the method precision. Sample analysis of 10 rice grain types (n = 30) available in the Asian market revealed that quinalphos, diazinon, and chlorpyrifos at concentrations of 1.08, 1.11, and 1.79 µg/kg, respectively, remained far below the maximum residue limits (0.01-0.5 mg/kg). However, regular monitoring is necessary to confirm that multiresidue occurrence remains below permissible limits while controlling pests. Environ Toxicol Chem 2020;39:1908-1917. © 2020 SETAC.
    Matched MeSH terms: Limit of Detection
  19. Optimizing conditions for methylmercury extraction from fish samples for GC analysis using response surface methodology
    Hajeb P, Jinap S, Abu Bakar F, Bakar J
    Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 2009 Jun;26(6):829-38.
    PMID: 19680957 DOI: 10.1080/02652030902751704
    Response surface methodology (RSM) was used to determine the optimum experimental conditions to extract methylmercury from fish samples for GC analysis. The influence of four variables - acid concentration (3-12 M), cysteine concentration (0.5-2% w/v), solvent volume (3-9 ml) and extraction time (10-30 min) - on recovery of methylmercury was evaluated. The detection limit for methylmercury analysis using a microelectron capture detector was 7 ng g(-1) in fish samples. The mean recovery under optimum conditions was 94%. Experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (r(2)) of 0.977. The four variables had a significant effect (p < 0.05) on the recovery of methylmercury from a reference material (BCR-463). Optimum conditions for methylmercury extraction were found using an acid concentration of 12.2 M, cysteine concentration of 2.4%, solvent volume of 1.5 ml and extraction time of 35 min. The validation of the developed method to analyze methylmercury in fish samples exhibited good agreement with mercury content in the samples.
    Matched MeSH terms: Limit of Detection
  20. Optimized fabrication of newly cholesterol biosensor based on nanocellulose
    Abdi MM, Razalli RL, Tahir PM, Chaibakhsh N, Hassani M, Mir M
    Int J Biol Macromol, 2019 Apr 01;126:1213-1222.
    PMID: 30611809 DOI: 10.1016/j.ijbiomac.2019.01.001
    A novel and sensitive electrochemical cholesterol biosensor was developed based on immobilization cholesterol oxidase (ChOx) on the polyaniline/crystalline nanocellulose/ionic liquid modified Screen-Printed Electrode (PANi/CNC/IL/SPE). A thin layer of ionic liquid (IL) was spin coated on the modified electrode to enhance the electron transferring. Crystalline nanocellulose was prepared from Semantan bamboo (Gigantochloa scortechinii) via acid hydrolysis and it was used to synthesize a nanocomposite of PANi/CNC via in situ oxidative polymerization process. FESEM and TEM images showed high porosity of the nanostructure with no phase separation, revealing the homogenous polymerization of the monomer on the surface of the crystalline cellulose. Research surface methodology (RSM) was carried out to optimize the parameters and conditions leading to maximize the performance and sensitivity of biosensors. The PANi/CNC/IL/GLU/ChOx-modified electrode showed a high sensitivity value of 35.19 μA mM/cm-2 at optimized conditions. The proposed biosensor exhibited a dynamic linear range of 1 μM to 12 mM (R2 = 0.99083) with the low Limit of Detection of 0.48 μM for cholesterol determination. An acceptable reproducibility (RSDs ≤3.76%) and repeatability (RSDs ≤3.31%) with the minimal interference from the coexisting electroactive compounds such as ascorbic acid, uric acid and glucose was observed for proposed biosensor.
    Matched MeSH terms: Limit of Detection
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