scholarly journals An Alternative Approach for the Detection of Ethephon (2-Chlorethylphosphonic acid) Residues in Apples

2006 ◽  
Vol 1 (4) ◽  
pp. 1934578X0600100
Author(s):  
Dietmar Kröpfl ◽  
Klaus Schweiger ◽  
Franz Siegfried Wagner ◽  
Elke Prettner
Keyword(s):  
Internal Standard ◽  
Good Method ◽  
Low Ph ◽  
Measurement Precision ◽  
Direct Extraction ◽  
Selected Ion Monitoring ◽  
Method Performance ◽  
Alternative Approach ◽  
The Matrix ◽  
One Step

A rapid and simple GC/MS method to detect ethephon residues in apples is introduced using an internal standard and direct extraction of the analytes from the matrix at low pH with ethyl acetate. A one step derivatization procedure has been established using N-tert-butyldimethylsilyl-N-methyltrifluoracetamide (MTBSTFA) prior to GC/MS analysis performed in selected ion monitoring mode (SIM). Optimization of the derivatization and GC- parameters led to good method performance and measurement precision. Recovery experiments showed recovery rates ranging from 80.8 to 95.5% in the concentration range were investigated. The presented method provides significant improvements in laboratory safety, sample throughput and instrumentation cost compared with other methods to detect ethephon residues in apples.

Determination of Clenbuterol in Cattle, Sheep, and Swine Tissues by Electron Ionization Gas Chromatography/Mass Spectrometry

1994 ◽  
Vol 77 (4) ◽  
pp. 917-924 ◽  
Author(s):  
Roger T Wilson ◽  
Joseph M Groneck ◽  
Kathleen P Holland ◽  
A Carolyn Henry
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Internal Standard ◽  
Electron Ionization ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Method Performance ◽  
Chromatography Mass Spectrometry ◽  
Coefficients Of Variation

Abstract A gas chromatographic/mass spectrometric procedure is described for the quantitation and confirmation of clenbuterol residues from cattle, sheep, and swine tissues. After liquid–liquid extraction and derivatization with phosgene in an aqueous pH 10.1 buffer, the cyclic oxazolidone derivative is quantitated with a clenbuterol analogue as internal standard (NAB-760 CI). Confirmation is accomplished by comparison of ion ratios with those of a pure synthesized standard of clenbuterol oxazolidin-3-one obtained by selected ion monitoring, electron ionization gas chromatography/mass spectrometry on a benchtop instrument. Statistical information based on a series of standard curves for fortified tissues is included to describe method performance. Ion ratio variations were under 15%, and coefficients of variation for spiked tissue standard curves were above 0.997. Recoveries averaged 87.1 ± 6.6% for liver tissues across all 3 species and 67.1 ± 3.8% for muscle tissue across all 3 species.

Development and Validation of an LC-MS/MS Method for Simultaneous Determination of Canagliflozin and Metformin HCl in Rat Plasma and its Application

2020 ◽  
Vol 16 (6) ◽  
pp. 752-762
Author(s):  
Vivek Nalawade ◽  
Vaibhav A. Dixit ◽  
Amisha Vora ◽  
Himashu Zade
Keyword(s):  
Internal Standard ◽  
Rat Plasma ◽  
Precipitation Method ◽  
Herbal Extracts ◽  
One Step ◽  
Precision And Accuracy ◽  
Development And Validation ◽  
The Impact ◽  
Metformin Hcl

Background: Food and herbal extracts rich in Quercetin (QRT) are often self-medicated by diabetics and can potentially alter the pharmacokinetics (PK) of Metformin HCl (MET) and Canagliflozin (CNG) leading to food or herb-drug interactions and reduced therapeutic efficacy. However, the impact of these flavonoids on the pharmacokinetic behaviour of MET and CNG is mostly unknown. Methods: A simple one-step protein precipitation method was developed for the determination of MET and CNG from rat plasma. The mobile phase chosen was MeOH 65% and 35% water containing 0.1% formic acid at a flow rate of 1mL/min. Results: The retention time of MET, internal standard (Valsartan) and CNG was 1.83, 6.2 and 8.2 min, respectively. The method was found to be linear in the range of 200 - 8000 ng/mL for CNG and 100 = 4000 ng/ml for MET. Precision and accuracy of the method were below 20% at LLOQ and below 15% for LQC, MQC, and HQC. Conclusion: The method was successfully applied for the determination of PK of MET and CNG by using 100 μL of rat plasma. QRT co-administration affects the PK parameters of MET and CNG. This alteration in PK parameters might be of significant use for clinicians and patients.

scholarly journals Development and Validation of a Sensitive, Specific and Reproducible UPLC-MS/MS Method for the Quantification of OJT007, A Novel Anti-Leishmanial Agent: Application to a Pharmacokinetic Study

2021 ◽  
Vol 18 (9) ◽  
pp. 4624
Author(s):  
Maria Rincon Nigro ◽  
Jing Ma ◽  
Ololade Tosin Awosemo ◽  
Huan Xie ◽  
Omonike Arike Olaleye ◽  
...  
Keyword(s):  
Formic Acid ◽  
High Performance ◽  
Leishmania Major ◽  
Internal Standard ◽  
Gradient Elution ◽  
Rat Plasma ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Positive Mode ◽  
Acquity Uplc

OJT007 is a methionine aminopeptidase 1 (MetAP1) inhibitor with potent anti-proliferative effects against Leishmania Major. In order to study its pharmacokinetics as a part of the drug development process, a sensitive, specific, and reproducible ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated. Voriconazole was used as the internal standard to generate standard curves ranging from 5 to 1000 ng/mL. The separation was achieved using a UPLC system equipped with an Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm) with 0.1% formic acid in acetonitrile and 0.1% formic acid in water as the mobile phase under gradient elution at a flow rate of 0.4 mL/min. The mass analysis was performed with a 4000 QTRAP® mass spectrometer using multiple-ion reaction monitoring (MRM) in the positive mode, with the transition of m/z 325 → m/z 205 for OJT007 and m/z 350 → m/z 101 for voriconazole. The intra- and inter-day precision and accuracy were within ±15%. The mean extraction recovery and the matrix effect were 95.1% and 7.96%, respectively, suggesting no significant matrix interfering with the quantification of the drug in rat plasma. This study was successfully used for the pharmacokinetic evaluation of OJT007 using the rat as an animal model.

scholarly journals Isotope analysis of highly enriched “silicon-28” by high-resolution inductively coupled plasma mass spectrometry using an internal standard

2021 ◽  
Vol 25 (2) ◽  
pp. 98-109
Author(s):  
P. A. Otopkova ◽  
◽  
A. M. Potapov ◽  
A. I. Suchkov ◽  
A. D. Bulanov ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Matrix Element ◽  
High Resolution ◽  
Inductively Coupled Plasma ◽  
Internal Standard ◽  
Isotopic Analysis ◽  
Random Component ◽  
Inductively Coupled ◽  
The Matrix ◽  
Plasma Mass Spectrometry

In order to study the isotopic effects in semiconductor materials, single crystals of high chemical and isotopic purity are required. The reliability of the obtained data on the magnitude and the direction of isotopic shifts depends on the accuracy of determining the concentration of all stable isotopes. In the isotopic analysis of enriched “silicon-28” with a high degree of enrichment (> 99.99%), it is necessary to determine the impurities of 29Si and 30Si isotopes at the level of 10-3 ¸ 10-5 at. %. At this concentration level, these isotopes can be considered as impurities. It is difficult to achieve high measurement accuracy with simultaneous registration of the main and “impurity” isotopes in such a wide range of concentrations. The registration of analytical signals of silicon isotopes must be carried out in the solutions with different matrix concentrations. The use of the solutions with the high concentration of the matrix element requires the introduction of corrections for matrix noise and the drift of the instrument sensitivity during the measurement. It is possible to reduce the influence of the irreversible non-spectral interference and sensitivity drift by using the method of internal standardization. The inconsistency of the literature data on the selection criteria for the internal standard required studying the behavior of the signals of the “candidates for the internal standard” for the ELEMENT 2 single-collector high-resolution inductively coupled plasma mass spectrometer on the matrix element concentration and the nature of the solvent, as well as on the solution nebulizing time. Accounting for the irreversible non-spectral matrix noise and instrumental drift in isotopic analysis of enriched “silicon-28” and initial 28SiF4 by inductively coupled plasma mass spectrometry had allowed us to reduce by 3-5 times the random component and by more than an order of magnitude the systematic component of the measurement error in comparison with the external standard method. This made it possible to carry out, with sufficient accuracy, the operational control of the isotopic composition of enriched “silicon-28”, both in the form of silicon tetrafluoride and polycrystalline silicon obtained from it, using a single serial device in the range of isotopic concentrations 0.0001–99.999%.

scholarly journals The absorption features of glycyrrhizic acid in composition of drug "phosphogliv"

2012 ◽  
Vol 58 (5) ◽  
pp. 564-572 ◽  
Author(s):  
A.A. Voskresenskaya ◽  
N.V. Medvedeva ◽  
V.N. Prozorovskiy ◽  
N.E. Moskaleva ◽  
O.M. Ipatova
Keyword(s):  
Sodium Salt ◽  
Glycyrrhizic Acid ◽  
Internal Standard ◽  
Absorption Efficiency ◽  
Drug Formulation ◽  
Peroral Administration ◽  
Glycyrrhetic Acid ◽  
Selected Ion Monitoring ◽  
Limit Of Quantification ◽  
Phospholipid Nanoparticles

Glycyrrhizic acid (GL) - one of the active components of the Russian drug formulation "Phosphogliv" possesses extremely low bioavailability. A sensitive method for GL determination in blood using high performance liquid chromatography coupled with mass-spectrometry (HPLC-MS) has been developed in order to investigate absorption characteristics of glycyrrhizic acid after peroral administration of "Phosphogliv" and GL sodium salt. Separation of blood components was achieved on the analytical reverse-phase column C18 "EcoNova" ProntoSIL, using a gradient mode. Detection of GL and an internal standard (IS) (glycyrrhetic acid) was performed using electrospray ionization with the selected ion monitoring in negative mode (SIM) using target ions at m/z 821.3 for GL and 469.3 for IS. The calibration curve was linear over the range of 50-5000 ng/ml (the correlation coefficient was 0.995). The detection limit for GL in blood was 25 ng/ml and the lower limit of quantification was 50 ng/ml.The developed method has been applied to compare absorption efficiency of glycyrrhizic acid as the component of "Phosphogliv" composition and solution of GL sodium salt during first two hours after their single peroral administration to rats at the dose of 8.5 mg/kg. It was shown that GL absorption occurs several minutes after peroral administration. Moreover, GL bioavailability after administration of drug "Phosphogliv" was higher than after administration of GL sodium salt. This difference may be attributed to incorporation of glycyrrhizic acid in the phospholipid nanoparticles structure.

Simultaneous Electrochemical Detection of Multiple Heavy-Metal Ions Based on Furfural/Reduced Graphene Oxide Composites

2021 ◽  
Author(s):  
Xiaoyun Xu ◽  
Xiaoyi Lv ◽  
Fei Tan ◽  
Yanping Li ◽  
Chao Geng ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Graphene Oxide ◽  
Metal Ions ◽  
Reduced Graphene Oxide ◽  
Heavy Metal Ions ◽  
Simultaneous Detection ◽  
Reduced Graphene ◽  
The Matrix ◽  
One Step ◽  
Oxide Composites

Abstract An efficient and sensitive electrochemical sensor for simultaneous detection of heavy metal ions was developed based on furfural/reduced graphene oxide composites (FF/RGO). The preparation of FF/RGO were performed through a one-step high-pressure assisted hydrothermal treatment, which is recommended as a green, convenient, and efficient way for the reduction of graphene oxide and the production of FF/RGO composites. RGO not only serves as the skeleton for furfural loading but also improves the conductivity of the composites in the matrix. FF/RGO with large specific surface area and abundant oxygen-containing functional groups was used to provide more binding sites for the effificient adsorption of heavy-metal ions due to the interaction between hydrophilic groups (-COOH, -OH, and -CHO) and metal cations. The developed sensor showed identifiable electrochemical response toward the heavy metal ions separately and simultaneously, exhibiting superior stability, outstanding sensitivity, selectivity and excellent analytical performance. Impressively, the sensor developed in this experiment has been successfully applied to the simultaneous determination of various heavy metal ions in actual samples, which has definitely exhibited a promising prospect in practical application.

scholarly journals Determination of Fumonisins B1 and B2 in Corn by LC/MS with Immunoaffinity Column Cleanup: Interlaboratory Study

2010 ◽  
Vol 93 (2) ◽  
pp. 611-621 ◽  
Author(s):  
Hamide Z Senyuva ◽  
John Gilbert ◽  
Joerg Stroka ◽  
S Biselli ◽  
A De Girolamo ◽  
...  
Keyword(s):  
Fine Powder ◽  
Immunoaffinity Column ◽  
Selected Ion Monitoring ◽  
Test Portion ◽  
Method Performance ◽  
Three Samples ◽  
Interlaboratory Validation ◽  
Cleanup Procedure ◽  
Phosphate Buffered Saline

Abstract An interlaboratory validation study was conducted to establish the method performance characteristics of an immunoaffinity column (IAC) cleanup procedure followed by LC/MS for the determination of fumonisins B1 (FB1) and B2 (FB2) and combined FB1 + FB2 in corn. The test portion is extracted with acetonitrilemethanolwater (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an IAC. FB1 and FB2 are removed with methanol, followed by water, then directly determined by RPLC with MS detection using selected-ion monitoring of two characteristic ions in each case. Naturally contaminated corn samples were milled to a fine powder and mixed to produce three samples with target levels of combined FB1 + FB2 ranging from 350 to 4000 g/kg. Of 15 initially participating laboratories, two failed to report results and another did not follow the prescribed method. Thus, valid results were obtained from 12 participants located in 11 countries. Statistical analysis of the results produced RSDr values of 4.611.9, 1.912.6, and 1.411.5 for FB1, FB2, and combined FB1 + FB2, respectively; the corresponding RSDR values were 19.823.8, 18.225.5, and 18.823.2. The three concentration levels of combined FB1 + FB2 were 534, 1194, and 1954 g/kg. HorRat values for r and R were all <2.0, indicating that the method is suitable as a regulatory method for the enforcement of European Union limits for fumonisins in corn.

Immunoadsorption to improve gas chromatography/high-resolution mass spectrometry of estradiol-17 beta in plasma.

1983 ◽  
Vol 29 (4) ◽  
pp. 677-680 ◽  
Author(s):  
S J Gaskell ◽  
B G Brownsey
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
High Resolution ◽  
High Resolution Mass Spectrometry ◽  
Trimethylsilyl Ether ◽  
Internal Standard ◽  
Selected Ion Monitoring ◽  
High Resolution Mass ◽  
Precise Quantification ◽  
Resolution Mass

Abstract We describe a new, highly selective procedure for the determination of estradiol-17 beta in plasma. Samples are extracted with a micro-cellulose-coupled antiserum to estradiol-17 beta. Conversion of the extracted steroid to the bis(trimethylsilyl) ether is followed by gas chromatography/high-resolution mass spectrometry with selected ion monitoring. Precise quantification is achieved through the use of [2H3]estradiol-17 beta as internal standard.

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