scholarly journals Offline Selective Extraction Combined with Online Enrichment for Sensitive Analysis of Chondroitin Sulfate by Capillary Electrophoresis

2020 ◽  
Vol 58 (9) ◽  
pp. 868-874
Author(s):  
Jie Gong ◽  
Guanglian Zhou ◽  
Yuanhong Wu ◽  
Siying Zhang ◽  
Xiumei Liu
Keyword(s):  
Capillary Electrophoresis ◽  
Chondroitin Sulfate ◽  
Limit Of Detection ◽  
Background Electrolyte ◽  
Selective Extraction ◽  
Detection Sensitivity ◽  
Calibration Plot ◽  
Sample Stacking ◽  
Relative Standard ◽  
Experimental Parameters

Abstract A capillary electrophoresis (CE) method combined with online and offline enrichment for improving the detection sensitivity of chondroitin sulfate (CS) is established. The online enrichment method is based on the field-amplified sample stacking and large volume electrokinetic injection, and offline enrichment is based on the association between cetyltrimethylammonium chloride and CS. Experimental parameters affecting CE method such as the type and pH of background electrolyte, the injection mode and time and the steps of offline enrichment were optimized. Under optimum conditions, the calibration plot between CS concentration and peak area was linear in the range of 1 ~ 100 μg/mL. The enrichment factor was 130 times and the limit of detection was 50 ng/mL. The average recovery was 103.5% and the relative standard deviation of peak area was <2.0%. The method was successfully applied to the quantitative analysis of CS in drugs.

scholarly journals Solid-Phase Extraction and Large-Volume Sample Stacking-Capillary Electrophoresis for Determination of Tetracycline Residues in Milk

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Gabriela Islas ◽  
Jose A. Rodriguez ◽  
Irma Perez-Silva ◽  
Jose M. Miranda ◽  
Israel S. Ibarra
Keyword(s):  
Capillary Electrophoresis ◽  
Solid Phase Extraction ◽  
Large Volume ◽  
Solid Phase ◽  
Phase Extraction ◽  
Sample Stacking ◽  
Milk Samples ◽  
Relative Standard ◽  
Tetracycline Residues ◽  
Large Volume Sample Stacking

Solid-phase extraction in combination with large-volume sample stacking-capillary electrophoresis (SPE-LVSS-CE) was applied to measure chlortetracycline, doxycycline, oxytetracycline, and tetracycline in milk samples. Under optimal conditions, the proposed method had a linear range of 29 to 200 µg·L−1, with limits of detection ranging from 18.6 to 23.8 µg·L−1 with inter- and intraday repeatabilities < 10% (as a relative standard deviation) in all cases. The enrichment factors obtained were from 50.33 to 70.85 for all the TCs compared with a conventional capillary zone electrophoresis (CZE). This method is adequate to analyze tetracyclines below the most restrictive established maximum residue limits. The proposed method was employed in the analysis of 15 milk samples from different brands. Two of the tested samples were positive for the presence of oxytetracycline with concentrations of 95 and 126 µg·L−1. SPE-LVSS-CE is a robust, easy, and efficient strategy for online preconcentration of tetracycline residues in complex matrices.

scholarly journals Electroanalysis Of Paracetamol By A Carbon Paste Electrode Modified By Zinc: Analytical Application In Human Blood

2021 ◽  
Vol 16 (1) ◽  
pp. 25-31
Author(s):  
Hayat EL Ouafy ◽  
Tarik EL Ouafy ◽  
Mustapha Oubenali ◽  
Mohamed Mbarki ◽  
Malika Echajia ◽  
...  
Keyword(s):  
Human Blood ◽  
Carbon Paste Electrode ◽  
Catalytic Effect ◽  
Limit Of Detection ◽  
Detection Sensitivity ◽  
Modified Carbon Paste Electrode ◽  
Potential Range ◽  
Carbon Paste ◽  
Relative Standard ◽  
Paste Electrode

The present work describes the catalytic effect of zinc particles for electroanalysis the paracetamol (PAR). The working electrode was prepared by mixing the zinc with the carbon powder. The voltammetric behavior of paracetamol was studied when an anodic peak to appear at 0.35 V in 0.1 M Na2SO4 solution (pH 12). The peak resulting from the irreversible oxidation of paracetamol on the zinc modified carbon paste electrode (Zn/CPE). The catalytic effect was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV). The electrocatalytic behavior of the zinc particles is allotted to its chemical and physical properties. This electrode has a good performance for the electroanalysis of paracetamol. To obtain an electrochemical analysis of paracetamol oxidation at the surface of Zn/CPE, the voltammograms are used in a potential range of - 1.5 V to 1.5 V. More, Zn/CPE can be utilized successfully to ameliorate the electroanalysis of paracetamol at very feeble concentration and with high detection sensitivity. The limit of detection (LD) and quantification (LQ) obtained are respectively 7.52·10-8 mol L-1 and 2.6·10-7 mol L-1. Then the relative standard deviation (RSD) at 2.0·10-5 mol L-1 PAR concentration was 2.88 % for nine repetitions. Afterward, the presented method was used to electroanalysis paracetamol in human blood samples with satisfying results.

scholarly journals Magnetic Ion Imprinted Polymers (MIIPs) for Selective Extraction and Preconcentration of Sb(III) from Environmental Matrices

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 21
Author(s):  
Silindokuhle Jakavula ◽  
Nkositetile Raphael Biata ◽  
Kgogobi M. Dimpe ◽  
Vusumzi Emmanuel Pakade ◽  
Philiswa Nosizo Nomngongo
Keyword(s):  
Environmental Samples ◽  
Limit Of Detection ◽  
Selective Extraction ◽  
Fractional Factorial ◽  
Emission Spectrometry ◽  
Icp Oes ◽  
Aquatic Life ◽  
Relative Standard ◽  
Ion Imprinted ◽  
Ion Imprinted Polymers

Antimony(III) is a rare element whose chemical and toxicological properties bear a resemblance to those of arsenic. As a result, the presence of Sb(III) in water might have adverse effects on human health and aquatic life. However, Sb(III) exists at very ultra-trace levels which may be difficult for direct quantification. Therefore, there is a need to develop efficient and reliable selective extraction and preconcentration of Sb(III) in water systems. Herein, a selective extraction and preconcentration of trace Sb(III) from environmental samples was achieved using ultrasound assisted magnetic solid-phase extraction (UA-MSPE) based on magnetic Sb(III) ion imprinted polymer-Fe3O4@SiO2@CNFs nanocomposite as an adsorbent. The amount of antimony in samples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The UA-MSPE conditions were investigated using fractional factorial design and response surface methodology based on central composite design. The Sb(III)-IIP sorbent displayed excellent selectivity towards Sb(III) as compared to NIIP adsorbent. Under optimised conditions, the enrichment factor, limit of detection (LOD) and limit of quantification (LOQ) of UA-MSPE/ICP-OES for Sb(III) were 71.3, 0.13 µg L−1 and 0.44 µg L−1, respectively. The intra-day and inter-day precision expressed as relative standard deviations (%RSDs, n = 10 and n = 5) were 2.4 and 4.7, respectively. The proposed analytical method was applied in the determination of trace Sb(III) in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95–98.3%.

Determination of Intact Heparin by Capillary Electrophoresis with Contactless Conductivity Detection in Background Electrolytes Containing Hydrophilic Polymers

2008 ◽  
Vol 73 (2) ◽  
pp. 187-200 ◽  
Author(s):  
Petr Tůma ◽  
Eva Samcová ◽  
František Opekar ◽  
Karel Štulík
Keyword(s):  
Capillary Electrophoresis ◽  
Blood Plasma ◽  
Limit Of Detection ◽  
Background Electrolyte ◽  
Inorganic Ions ◽  
Hydroxyethyl Cellulose ◽  
Conductivity Detection ◽  
Contactless Conductivity Detection ◽  
In Blood Plasma

Intact heparin was characterized and determined in model samples, in infusion solutions and in blood plasma by capillary electrophoresis (CE) with contactless conductivity detection. The CE separation of polydisperse heparin took place in open silica capillaries, in electrolytes containing a polymer (hydroxyethyl)cellulose, poly(ethylene glycol) or dextran. The best separation of heparin from excess inorganic ions present in real samples was attained in a background electrolyte consisting of 0.8 M acetic acid and 1% (w/v) dextran (100 kDa). The limit of detection (LOD) was 1.3 μmol l-1. This electrolyte was used in determination of heparin in blood plasma and in infusion solutions.

scholarly journals Analytical Study of Comprehensive and Targeted Multidimensional Gas Chromatography Incorporating Modulated Cryogenic Trapping

2001 ◽  
Vol 84 (2) ◽  
pp. 323-336 ◽  
Author(s):  
Thy T Truong ◽  
Philip J Marriott ◽  
Nichola A Porter
Keyword(s):  
Gas Chromatography ◽  
Normal Mode ◽  
Analytical Study ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Complete Separation ◽  
Pollution Monitoring ◽  
Detection Sensitivity ◽  
Constant Frequency ◽  
Relative Standard

Abstract This paper reports the results of an analytical study comparing capillary gas chromatography (GC) operated in the normal mode with 2 new GC techniques, comprehensive GC (GC × GC) and targeted (or selective) multidimensional GC, which use a longitudinally modulated cryogenic system (LMCS), recently developed in our laboratory. A high-temperature application of derivatized sterols, of interest in fecal pollution monitoring, was chosen for this work. A directly connected coupled-column ensemble was used, comprising a nonpolar column and a moderately polar column. With LMCS, effluent from the first column is zone-compressed in a cryogenic trap and then pulsed to a short second column, producing narrower peaks with sharp, tall peak responses at the detector. The modulator is operated at a constant frequency, e.g., 0.25 s−1, to produce the GC × GC result, or is moved in a predefined manner so that whole peaks are selectively trapped and subsequently pulsed through to the second column in the targeted mode. Standard solutions containing a mixture of 7 sterols and 5-α-cholestane internal standard were used. Detection sensitivity is increased by a factor of ≥25 with the use of LMCS. The estimated limit of detection was about 0.1 μg/mL when normal GC with flame ionization detection (GC/FID) and a 1.0 μL splitless injection volume were used, compared with 0.02 and 0.004 μg/mL for the LMCS operated in GC × GC and selective modes, respectively. Calibration curves for GC/FID were linear over the 0.1–2.0 μg/mL range tested. Reproducibilities for the GC × GC and normal GC modes were comparable; generally, relative standard deviations (RSD) were on the order of 3–4%, based on raw peak responses. Improved reproducibility was found for selective LMCS operation, at an RSD of around 2%; with internal standardization, better results were achieved. The coupled-column arrangement allowed complete separation of sterol peaks from overlapping impurity peaks in a number of instances with LMCS modes, and its use should improve data quality over that of normal GC operation, in which the overlapping peaks interfere with measurement of peak response in the normal mode.

A Selective and Sensitive Method Development and Validation of 1,1-Dimethyl-3-Hydroxy-Pyrrolidinium Bromide Impurity in Glycopyrrolate Oral Solution by Liquid Chromatography–Tandem Mass Spectroscopy

2021 ◽  
Author(s):  
Rajesh Kumar Chawla ◽  
G S N Koteswara Rao ◽  
Umasankar Kulandaivelu ◽  
Siva Prasad Panda ◽  
Rajasekhar Reddy Alavala
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Method Development ◽  
Limit Of Detection ◽  
Oral Solution ◽  
Calibration Plot ◽  
Tandem Mass ◽  
Relative Standard ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass

Abstract Objective A selective and sensitive liquid chromatography–tandem mass spectrometer (LC–MS/MS) method has been developed for the quantification of 1,1-dimethyl-3-hydroxy-pyrrolidinium bromide impurity in glycopyrrolate oral solution. Materials and method The LC–MS/MS analysis was done on X Bridge HILIC (100 × 4.6 mm, 5 μm) analytical column, and the mobile phase used was10 mM ammonium formate with 0.2% formic acid as mobile phase-A and acetonitrile as mobile phase-B with a gradient programme of 5.0 min. The flow rate used was 1.2 mL/min. Triple quadrupole mass detector coupled to positive electrospray ionization operated in multiple reactions monitoring mode was used for the quantification at m/z 116.10 ± 0.5. Results Retention time of impurity was found ~3.2 min. The method was validated in terms of specificity, linearity, accuracy, precision, range, limit of detection, limit of quantitation (LOQ) and robustness. Relative standard deviation (RSD) for system suitability was found 1.3%. Calibration plot was linear over the range of 0.050–2.000 μg/mL. Limit of detection and limit of quantification were found 0.017 and 0.051 μg/mL, respectively. The intra- and inter-day precision RSD was 2.3% and the obtained recovery at LOQ to 200% was in between 86.7 and 107.4%. Conclusion The low RSD values and high recoveries of the method confirm the suitability of the method.

scholarly journals Determination of Chondroitin Sulfate Content in Raw Materials and Dietary Supplements by High-Performance Liquid Chromatography with Ultraviolet Detection After Enzymatic Hydrolysis: Single-Laboratory Validation

2007 ◽  
Vol 90 (3) ◽  
pp. 659-669 ◽  
Author(s):  
David Ji ◽  
Mark Roman ◽  
Joseph Zhou ◽  
Jana Hildreth
Keyword(s):  
Liquid Chromatography ◽  
Chondroitin Sulfate ◽  
Dietary Supplements ◽  
Limit Of Detection ◽  
Raw Materials ◽  
Negative Control ◽  
Sulfate Content ◽  
Ultraviolet Detection ◽  
Relative Standard ◽  
Single Laboratory

Abstract A method to quantify chondroitin sulfate in raw materials and dietary supplements at a range of about 5 to 100% (w/w) chondroitin sulfate has been developed and validated. The chondroitin sulfate is first selectively hydrolyzed by chondroitinase ACII enzyme to form un-, mono-, di-, and trisulfated unsaturated disaccharides; the resulting disaccharides are then quantified by ion-pairing liquid chromatography with ultraviolet detection. The amounts of the individual disaccharides are summed to yield the total amount of chondroitin sulfate in the material. Single-laboratory validation has been performed to determine the repeatability, accuracy, selectivity, limit of detection, limit of quantification, ruggedness, and linearity of the method. Repeatability precision for total chondroitin sulfate content was between 1.60 and 4.72% relative standard deviation, with HorRat values between 0.79 and 2.25. Chondroitin sulfate recovery from raw material negative control was between 101 and 102%, and recovery from finished product negative control was between 105 and 106%.

scholarly journals Determination of Diazepam in Cream Biscuits by Liquid Chromatography

2004 ◽  
Vol 87 (3) ◽  
pp. 569-572 ◽  
Author(s):  
Priyankar Ghosh ◽  
Mudiam Mohanakrishna Reddy ◽  
Beedu Sashidhar Rao ◽  
Rajendra Kumar Sarin
Keyword(s):  
Retention Time ◽  
Mobile Phase ◽  
Limit Of Detection ◽  
Linear Regression Analysis ◽  
Internal Standard ◽  
Reversed Phase ◽  
Calibration Plot ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract An analytical procedure was developed for the detection and quantitation of diazepam in cream biscuits, which were used to commit crime. The method involves the extraction of diazepam with ethanol at room temperature, and the extract is filtered, evaporated to dryness, and redissolved in the mobile phase, methanol–acetonitrile–tetrahydrofuran–water (15 + 55 + 4 + 26, v/v). The separation is achieved on a C18 reversed-phase column with the mobile phase and diode array detection (λmax) at 230 nm. Medazepam is used as the internal standard is for quantification. The calibration plot for the determination of diazepam is based on linear regression analysis (y = 0.6687x + 0.0372; r2 = 0.995). The limit of detection for diazepam in the biscuit samples was estimated as 600 ng/mL. The limit of quantitation for diazepam was estimated as 1.75 μg/mL. The diazepam detected per piece of biscuit was found to be in the range of 0.27–0.45 mg. Pure diazepam was added to biscuit samples at 3 levels (100 and 500 μg/g, and 1 mg/g), and the recoveries were found to be 95%. The mean retention time of diazepam was 2.7 min and that of medazepam (IS) was 4 min. The relative standard deviations of the diazepam level in the biscuit samples were estimated to be 0.4% for retention time and 1.02% for peak area in intraday analysis, whereas the corresponding values were and 0.61 and 2.34% in interday analysis. The method is rapid and reliable for qualitative and quantitative analysis of cream biscuits laced with diazepam, and it can be used by law enforcement laboratories for routine analysis.

scholarly journals Capillary Electrophoresis–Mass Spectrometry with Multisegment Injection and In-Capillary Preconcentration for High-Throughput and Sensitive Determination of Therapeutic Decapeptide Triptorelin in Pharmaceutical and Biological Matrices

Biomedicines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1488
Author(s):  
Juraj Piešťanský ◽  
Ivana Čižmárová ◽  
Ondrej Štefánik ◽  
Michaela Matušková ◽  
Andrea Horniaková ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Capillary Electrophoresis ◽  
Separation Efficiency ◽  
Limit Of Detection ◽  
Analytical Signal ◽  
Clinical Analysis ◽  
Performance Parameters ◽  
Biological Matrices ◽  
Relative Standard

A capillary electrophoresis–tandem mass spectrometry method with a multisegment injection and an in-capillary field-enhanced sample stacking for determination of therapeutic peptide triptorelin in pharmaceutical and biological matrices was developed. The CE separation conditions were optimized in order to obtain maximal separation efficiency, analytical signal intensity and stability, and minimal adsorption of the analyzed peptide onto the capillary wall (1 M formic acid – HFo, pH 1.88). The implementation of the field-enhanced sample injection into CE improved the value of limit of detection 50 times while the multisegment injection increased the sample throughput three times in comparison to a conventional CE approach. The proposed method was characterized by favorable performance parameters, such as linearity (r2 ≥ 0.99), limit of detection (5 ng mL−1 in water matrix, 25 ng mL−1 in plasma matrix), precision (relative standard deviation, 1.5–9.4% for intraday and 2.3–11.9% for interday reproducibility), or accuracy (relative errors in the range of 80–109%). The FDA-validated method was successfully applied to the analysis of triptorelin in the commercial drug Diphereline® 0.1 mg (powder for injection) and in spiked human plasma samples. Favorable performance parameters along with proven application potentialities indicate the usefulness of the proposed method for its routine use in drug quality control laboratories and for clinical analysis, such as determination of triptorelin levels in plasma (for pharmacokinetic study).

scholarly journals Determination of hexachlorophene in cosmetics by capillary electrophoresis compared with high performance liquid chromatography

2020 ◽  
pp. 1-7
Author(s):  
Xiaobin Li ◽  
Fangfang Gao ◽  
Huitao Liu ◽  
Yuan Gao
Keyword(s):  
High Performance Liquid Chromatography ◽  
Capillary Electrophoresis ◽  
Liquid Chromatography ◽  
High Performance ◽  
Limit Of Detection ◽  
Electrophoretic Analysis ◽  
Uv Detection ◽  
National Standards ◽  
Relative Standard

Abstract A simple capillary electrophoresis (CE) method with ultraviolet (UV) detection was developed for the determination of hexachlorophene (HCP) in cosmetics. Separation conditions were obtained in 20 mM Na2B4O7, 10% MeOH (pH 9.20), with 25 kV applied voltage and UV detection at 208 nm. Under the selected conditions, electrophoretic analysis was completed in about 4 min, with limit of detection (LOD) of 0.06 µg·mL−1 for HCP. The method was successfully applied to determine HCP in three kinds of cosmetics with relative standard deviations (RSD) of 0.52–3.02% and recoveries from 90.0 to 96.4% for the spiked samples. The results indicated that the proposed method was reliable. Comparative experiments were also carried out with high-performance liquid chromatography (HPLC)-UV method described in National Standards of People's Republic of China. The validation results of the two methods are comparable, but the proposed CE method is simple, rapid, which makes separation and analyte quantification in shorter time with much less reagent consumption.

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