scholarly journals Towards adaptive method for peak migration time correction: discretization period in electropherograms

Chemija ◽  
2020 ◽  
Vol 31 (3) ◽  
Author(s):  
Tomas Drevinskas ◽  
Audrius Maruška ◽  
Gintarė Naujokaitytė ◽  
Laimutis Telksnys ◽  
Mihkel Kaljurand ◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Adaptive Method ◽  
Reference Points ◽  
Migration Time ◽  
Time Shift ◽  
Internal Standards ◽  
Relative Standard ◽  
Adaptive Peak ◽  
Time Correction ◽  
Computationally Intensive

Capillary electrophoresis often causes unrepeatable peak migration times in the electropherogram due to changes of electroosmosis, yet in some cases this separation technique does not have a replacement alternative. Some attempts to overcome this issue have been performed introducing internal standards into the sample and compensating peak shifting in time. However, existing vector calculation-based methods are computationally intensive for portable instrumentation and usually limited to post-processing applications with 1 or 2 markers. In this work, an original approach of compensating peak migration time shift via signal discretization period correction is proposed. Using the proposed method, the number of reference points or markers that are used for compensation is extended. This method is effective in compensating migration time of peaks in real samples, where high sample injection volumes are used. Using 4 reference peaks in compensation, the method was capable of reducing the relative standard deviation of migration time of the peaks in the electropherograms more than 15 times. Corrected signal discretization periods indicated very high correlations with recorded separation currents, what can be perspective developing an adaptive peak migration time compensation method in capillary electrophoresis.

scholarly journals The Development and Validation of a Novel Designer Benzodiazepines Panel by LC–MS-MS

2021 ◽  
Author(s):  
Rebecca A Mastrovito ◽  
Donna M Papsun ◽  
Barry K Logan
Keyword(s):  
Illicit Drug ◽  
Liquid Extraction ◽  
Electrospray Tandem Mass Spectrometry ◽  
Method Performance ◽  
Internal Standards ◽  
Liquid Liquid Extraction ◽  
Relative Standard ◽  
Development And Validation ◽  
Positive Ion ◽  
Designer Benzodiazepines

Abstract Novel illicit benzodiazepines are among the most active areas of new illicit drug manufacture and use. We describe a method for the detection and quantification of etizolam and its metabolite α-hydroxyetizolam, flubromazolam, clonazolam, diclazepam, delorazepam, bromazepam, flubromazepam, phenazepam, flualprazolam, flunitrazolam, and nitrazolam in human whole blood. After addition of internal standards, samples are buffered and extracted using a liquid–liquid extraction. Analysis is performed using positive-ion electrospray tandem mass spectrometry for detection and quantitation. Calibration ranges were established based on the method performance and differed from compound to compound. Replicates at the lowest calibration point for each compound performed within 5% of CV (Coefficient of Variation). The correlation coefficient was >0.990 for all compounds. Relative standard deviation for all compounds was ≤10% of CV and accuracy was  ±10% for both within- and between-run experiments. The maximum average intra- and inter-run imprecision were 5.7%. The maximum average intra- and inter-run imprecision was −8.7%. As part of evaluating the scope for relevancy, samples testing positive in immunoassay but confirmed to be negative in traditional benzodiazepine confirmation method were re-analyzed using this method. The presence of at least one novel benzodiazepine was identified in 70% of these samples. The appearance of these novel “designer” benzodiazepines demonstrates the challenge for toxicology testing and the need for continually updated confirmation methods.

Detection of 20 Phthalate Esters in Different Kinds of Food Packaging Materials by GC-MS/MS with Five Internal Standards

2019 ◽  
Vol 102 (1) ◽  
pp. 255-261 ◽  
Author(s):  
Ji-cai Fan ◽  
Quan Jin ◽  
Hua-li He ◽  
Ren Ren ◽  
Shu-ting Wang
Keyword(s):  
Food Packaging ◽  
Large Scale ◽  
Phthalate Esters ◽  
Correlation Coefficients ◽  
Packaging Materials ◽  
Purification Step ◽  
Internal Standards ◽  
Extraction Solvent ◽  
Food Packaging Materials ◽  
Relative Standard

Abstract Background: Phthalate esters (PAEs) are a group of chemical compounds widely used as plasticizers to increase the flexibility of plastics that are used in the manufacturing of kitchen utensils and food containers. Objective: In this study, a simple, rapid, and sensitive method for the determination of 20 PAEs in different kinds of food packaging materials has been developed. Methods: Samples injected with five internal standards were extracted with acetonitrile saturated with n-hexane and then detected by GC-MS/MS without a purification step. Results: The standard calibration curves were linear for all analytes over the concentration range of 5–500 μg/L, and the correlation coefficients ranged from 0.9913 to 0.9999. The LODs and LOQs were in the ranges of 1.7–62.5 and 5.5–208.3 μg/kg, respectively. The accuracy of this method was evaluated by measuring the recovery from spiked samples. The recoveries of all 20 phthalates from samples spiked at three different concentrations were measured, and the recovery was in the range of 82.1–110.8% and the relative standard deviation range of recovery result (n = 6) was 0.3–9.7%. Conclusions: The method presented here is simple, rapid, and sensitive and can be applied to large-scale detection of PAEs in plastic materials. Highlights: Instead of only one solvent, acetonitrile saturated with n-hexane was used as the extraction solvent. Samples were pretreated without a purification step. Five internal standards were used for quantitative determination.

Analysis of Synthetic Antioxidant in Food by Capillary Electrophoresis

2011 ◽  
Vol 361-363 ◽  
pp. 1855-1858 ◽  
Author(s):  
Qian Xiang ◽  
Ying Gao
Keyword(s):  
Capillary Electrophoresis ◽  
Amperometric Detection ◽  
Peak Height ◽  
Butylated Hydroxyanisole ◽  
Applied Potential ◽  
Synthetic Antioxidant ◽  
Separation Potential ◽  
Relative Standard ◽  
Capillary Electrophoretic

A capillary electrophoretic assay for determining synthetic antioxidant butylated hydroxyanisole in food has been developed. The extraction with 70% (v/v) methanol quantitatively extracted synthetic antioxidant. The separation was carried out by CZE using phosphate at a separation potential of 18 kV. Amperometric detection was achieved with an applied potential of 0.60 V. A linear relationship between the peak height and the concentration of the analyte was found in the range 1.8-180 µg/mL for BHA, with correlation coefficient of 0.994. The relative standard deviations of migration time and peak height were 0.19 and 5.3 %, respectively. The method developed was successfully applied for the determination of synthetic antioxidant butylated hydroxyanisole in food. Recovery of butylated hydroxyanisole was 93%.

Molecular sieving polymer for DNA/RNA separation in capillary electrophoresis

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744094 ◽  
Author(s):  
Chenchen Liu ◽  
Yoshinori Yamaguchi ◽  
Xiaoming Dou
Keyword(s):  
Capillary Electrophoresis ◽  
Small Rna ◽  
Polymer Concentration ◽  
Migration Time ◽  
Migration Behavior ◽  
Molecular Weights ◽  
Rna Fragments ◽  
Molecular Sieving

In capillary polymer electrophoresis, the property of polymer sieving matrix dominates the migration behavior of DNA/RNA. We investigated the capillary electrophoresis of RNA ranging from 100 nt to 10,000 nt in polyacrylamide (PA) solutions with different molecular weights (Mw) and different concentrations. We observed that the resolution length (RSL) of RNA fragments was improved and the migration time was prolonged, when polymer concentration was increased. The resolution for small RNA fragments ([Formula: see text]1000 nt) was improved with the increase of polymer concentration, whereas the large ones ([Formula: see text]3000 nt) became inseparable. In addition, we estimated the smallest resolvable nucleotide length (Ls) by the plot of RSL against RNA size.

Capillary electrophoresis of wheat gliadin proteins and its potential for wheat varietal identification using pattern matching software

2001 ◽  
Vol 52 (8) ◽  
pp. 839 ◽  
Author(s):  
S. Siriamornpun ◽  
M. Wootton ◽  
J. M. Cox ◽  
F. Bekes ◽  
C. W. Wrigley
Keyword(s):  
Capillary Electrophoresis ◽  
Pattern Matching ◽  
Processing Parameters ◽  
Peak Height ◽  
Fused Silica ◽  
Constant Current ◽  
Good Resolution ◽  
Relative Mobility ◽  
Window Width ◽  
Relative Standard

Gliadins from 11 wheat flours were extracted with 30% ethanol and fractionated by capillary electrophoresis on a 20-µm i.d. untreated fused silica capillary using 0.1 M phosphate buffer (pH 2.5) containing polymer modifier. Capillary electrophoresis conducted at a constant current provided very good resolution and reproducibility (relative standard deviation <0.5) in mp;lt;15 min. Pattern matching of the profiles was performed with the PatMatch program to provide quantitative comparisons, using the relative mobility and intensity data for each gliadin protein. Data processing parameters, including the integration of the electrophoregram, were optimised for separation of gliadins extracted from either whole-grain or flour samples. The reproducibility and repeatability were compared using peak height and/or area percentages. The optimal window width for identifying matching gliadin peaks was 0.80–1.20% relative mobility units. Using these conditions, it was concluded that unknown varieties could be identified with a confidence level of 90–95%.

scholarly journals Determination of the Cross-Reactivities for -Zearalenol, -Zearalenol, Zearalanone, -Zearalanol, and -Zearalanol on Three Commercial Immunoaffinity Columns Targeting Zearalenone

2007 ◽  
Vol 90 (4) ◽  
pp. 1197-1202 ◽  
Author(s):  
Marianne Erbs ◽  
Nccolo Hartmann ◽  
Thomas D Bucheli
Keyword(s):  
Internal Standards ◽  
River Water Samples ◽  
Chromatography Tandem Mass Spectrometry ◽  
Relative Standard ◽  
Competition Effects ◽  
Liquid Chromatography Tandem Mass ◽  
Mycotoxin Analysis ◽  
Immunoaffinity Columns ◽  
Antibody Specificities

Abstract Immunoaffinity extraction has become increasingly important as a sample preparation and cleanup method in mycotoxin analysis. In this study, the antibody specificities of 3 commercial immunoaffinity columns (IACs) targeting zearalenone (ZON) were compared for -zearalenol, -zearalenol, zearalanone, -zearalanol, and -zearalanol. The recoveries of ZON and its 5 analogs were determined in triplicate when extracted from 10 mL circumneutral river water samples spiked with 20 ng analyte individually or in a mixture. The analytes were analyzed by means of electrospray ionization liquid chromatography/tandem mass spectrometry using deuterated internal standards for quantitation. Recoveries ranged from 69 to 115% for all analytes with relative standard deviations of 139%. Cross-reactivities for the analogs were &gt;80% when applied both individually and in a mixture. No significant competition effects were observed when the compounds were applied as a multianalyte mixture well below the stated IAC capacities. The results obtained here demonstrate that all IACs tested are highly cross-reactive towards the 5 ZON derivatives and may be applied for their simultaneous extraction or cleanup.

scholarly journals Development of a Capillary Electrophoresis Method for the Enantioselective Estimation of Primaquine in Pharmaceutical Formulations

2008 ◽  
Vol 91 (3) ◽  
pp. 536-541 ◽  
Author(s):  
Abdalla A Elbashir ◽  
Bahruddin Saad ◽  
Abdussalam Salhin Mohamed Ali ◽  
Muhammad Idiris Saleh
Keyword(s):  
Capillary Electrophoresis ◽  
Applied Voltage ◽  
Pharmaceutical Formulations ◽  
Fused Silica ◽  
Chiral Selector ◽  
Effective Length ◽  
Racemic Mixture ◽  
Injection Time ◽  
Relative Standard ◽  
Capillary Temperature

Abstract A capillary electrophoresis (CE) method has been developed that allows the separation and estimation of primaquine enantiomers using hydroxypropyl--cyclodextrin (HP--CD) as a chiral selector. The influence of chemical and instrumental parameters on the separation, such as type and concentration of CD, buffer concentration, buffer pH, applied voltage, capillary temperature, and injection time, were investigated. Good separation of the racemic mixture of primaquine was achieved using a fused-silica capillary (52.5 cm effective length 50 m id) and a background electrolyte composed of tris-phosphate buffer solution (50 mM, pH 2.5) containing 15 mM HP--CD as a chiral selector. The recommended applied voltage, capillary temperature, and injection time were 15 kV, 25C, and 6 s, respectively. Within-day and interday reproducibility of peak area and migration time gave relative standard deviation values ranging from 1.053.30. Good recoveries (range of 96.8104.9) were obtained from the determination of placebos that were spiked with 0.251.00 mg/L primaquine. The proposed CE method was successfully applied to the assay of primaquine diphosphate in pharmaceutical formulations (tablets).

scholarly journals Profiling of Amino Acids in Urine Samples of Patients Suffering from Inflammatory Bowel Disease by Capillary Electrophoresis-Mass Spectrometry

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3345 ◽  
Author(s):  
Juraj Piestansky ◽  
Dominika Olesova ◽  
Jaroslav Galba ◽  
Katarina Marakova ◽  
Vojtech Parrak ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Inflammatory Bowel Disease ◽  
Capillary Electrophoresis ◽  
Amino Acid ◽  
Bowel Disease ◽  
Urine Samples ◽  
Simultaneous Action ◽  
Relative Standard ◽  
Inflammatory Bowel

Urine represents a convenient biofluid for metabolomic studies due to its noninvasive collection and richness in metabolites. Here, amino acids are valuable biomarkers for their ability to reflect imbalances of different biochemical pathways. An impact of amino acids on pathology, prognosis and therapy of various diseases, including inflammatory bowel disease (IBD), is therefore the subject of current clinical research. This work is aimed to develop a capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the quantification of the 20 proteinogenic amino acids in human urine samples obtained from patients suffering from IBD and treated with thiopurines. The optimized CE-MS/MS method, with minimum sample preparation (just “dilute and shoot”), exhibited excellent linearity for all the analytes (coefficients of determination were higher than 0.99), with inter-day and intra-day precision yielding relative standard deviations in the range of 0.91–15.12% and with accuracy yielding relative errors in the range of 85.47–112.46%. Total analysis time, an important parameter for the sample throughput demanded in routine practice, was shorter in ca. 17% when compared to established CE-MS methods. Favorable performance of the proposed CE-MS/MS method was also confirmed by the comparison with corresponding ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) method. Consistent data for the investigated amino acid metabolome were obtained using both methods. For the first time, the amino acid profiling by CE-MS approach was applied on the clinical IBD samples. Here, significant differences observed in the concentration levels of some amino acids between IBD patients undergoing thiopurine treatment and healthy volunteers could result from the simultaneous action of the disease and the corresponding therapy. These findings indicate that amino acids analysis could be a valuable tool for the study of mechanism of the IBD treatment by thiopurines.

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