scholarly journals Preparation of Isotopically Labelled Standards of Creatinine Via H/D Exchange and Their Application in Quantitative Analysis by LC-MS

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1514
Author(s):  
Remigiusz Bąchor ◽  
Andrzej Konieczny ◽  
Zbigniew Szewczuk
Keyword(s):  
Internal Standard ◽  
Test Method ◽  
Simple Test ◽  
Liquid Chromatography Mass Spectrometry ◽  
Creatinine Concentration ◽  
Back Exchange ◽  
Acidic Conditions ◽  
Facile Preparation ◽  
The Stability ◽  
Neutral Conditions

Kidneys play a crucial role in maintaining metabolic homeostasis in a body. Serum creatinine concentration is a simple test used as an indicator of renal function. One of the known ways of quantifying creatinine concentration is the liquid chromatography-mass spectrometry (LC-MS) method, using an isotopically labeled analog of creatinine as an internal standard. Unfortunately, such isotope-labeled analogs are expensive and their synthesis is complex. Here we demonstrate a facile preparation of deuterated analogues of creatinine, via the H/D exchange of hydrogens located at the α-carbon (α-C) of the N-methylated amino acid part, under basic conditions. The stability of retrieved isotopologues was analyzed under both neutral or acidic conditions, and the results revealed that the introduced deuterons do not undergo back-exchange. In addition, the coelution of deuterated and non-deuterated forms under acidic and neutral conditions was observed. The prepared isotopologues were successfully applied in the quantitative LC-MS analysis of urine samples, and the results demonstrated that the presented strategy is novel and inexpensive, and that the quantification correlates with the commonly used Jaffe test method.

scholarly journals An assessment of methanolysis and other factors used in the analysis of carbohydrate-containing materials

1971 ◽  
Vol 125 (4) ◽  
pp. 1009-1018 ◽  
Author(s):  
R. E. Chambers ◽  
J. R. Clamp
Keyword(s):  
Hydrochloric Acid ◽  
Analytical Procedure ◽  
Internal Standard ◽  
Inorganic Contaminants ◽  
Rotary Evaporation ◽  
Silver Salts ◽  
Methanolic Hydrochloric Acid ◽  
Different Temperatures ◽  
The Stability ◽  
Analytical System

The stability of monosaccharides in methanolic hydrochloric acid of different strengths and at different temperatures was determined. They are generally stable for 24h in methanolic 1m- and 2m-hydrochloric acid at both 85°C and 100°C, but undergo considerable destruction in methanolic 4m- and 6m-hydrochloric acid at 100°C. Analysis of glycopeptides and oligosaccharides of known composition showed that release of carbohydrate was complete within 3h in methanolic 1m-hydrochloric acid at 85°C. Removal of methanolic hydrochloric acid by rotary evaporation resulted in considerable losses of monosaccharides, which could be prevented by prior neutralization. Methanolysis caused extensive de-N-acetylation of acetamidohexoses, so that a re-N-acetylation step is necessary in the analytical procedure. The addition of acetic anhydride for this purpose also prevented loss of internal standard by adsorption on the insoluble silver salts used in neutralization. Several trimethylsilylating agents were studied and suitable conditions are recommended. The effects on the analytical system of water and some common organic and inorganic contaminants are assessed.

scholarly journals Delayed Trilateral Teleoperation of a Mobile Robot

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
D. Santiago ◽  
E. Slawiñski ◽  
V. Mut
Keyword(s):  
Stability Analysis ◽  
Mobile Robot ◽  
Shared Environment ◽  
Time Varying ◽  
Control Parameters ◽  
Simple Test ◽  
Control Loop ◽  
Teleoperation System ◽  
Human Operators ◽  
The Stability

This paper analyzes the stability of a trilateral teleoperation system of a mobile robot. This type of system is nonlinear, time-varying, and delayed and includes a master-slave kinematic dissimilarity. To close the control loop, three P+d controllers are used under a position master/slave velocity strategy. The stability analysis is based on Lyapunov-Krasovskii theory where a functional is proposed and analyzed to get conditions for the control parameters that assure a stable behavior, keeping the synchronism errors bounded. Finally, the theoretical result is verified in practice by means of a simple test, where two human operators both collaboratively and simultaneously drive a 3D simulator of a mobile robot to achieve an established task on a remote shared environment.

scholarly journals Assessment of Micral-Test Microalbuminuria Test Strip in the Laboratory and in Diabetic Outpatients

1992 ◽  
Vol 29 (1) ◽  
pp. 96-100 ◽  
Author(s):  
Denis R Jury ◽  
Donald J Mikkelsen ◽  
Deborah Glen ◽  
Peter J. Dunn
Keyword(s):  
Screening Method ◽  
Urine Osmolality ◽  
Test Strip ◽  
Albumin Concentration ◽  
Creatinine Concentration ◽  
Urine Albumin ◽  
Low Concentrations ◽  
Colour Development ◽  
The Stability ◽  
Sodium And Potassium

We have evaluated a semi-quantitative dry immunochemical screening method (Micral-Test) for the detection of low concentrations of albumin in urine. The stability of Micral-Test strips on storage was good, especially with regard to temperature, light and humidity. Changes in urine osmolality (urea and creatinine concentration), pH and sodium and potassium concentration did not have a significant analytical effect on the Micral-Test measurement; extremes of temperature altered the rate of colour development. The depth of dipping the strip into the sample and the timing of reading colour development were critical. We measured the albumin concentration in 184 urine samples from diabetic outpatients by the Micral-Test and by our in-house immunoturbidimetric method; a Micral-Test result of 20 mg/L had a sensitivity of 91% and specificity of 97% to predict a discriminating urine albumin concentration > 30 mg/L by the in house method. The Micral-Test is suitable for use by non-laboratory personnel and is capable of producing analytically acceptable results for use in diabetes clinics and by general practitioners.

scholarly journals LABORATORY TESTING OF LEICA AT401 LASER TRACKER

2016 ◽  
Vol 56 (2) ◽  
pp. 88 ◽  
Author(s):  
Filip Dvořáček
Keyword(s):  
Laboratory Testing ◽  
Laboratory Tests ◽  
Angle Measurement ◽  
Distance Measurement ◽  
Additive Constant ◽  
Laser Tracker ◽  
Simple Test ◽  
Absolute Distance ◽  
Warm Up ◽  
The Stability

<p>This paper describes laboratory tests on a Leica AT401laser tracker. As the newer Leica AT402 model also uses the same firmware package, most of the results should also be valid for this device. First, we present the instrument’s firmware errors and the software used for testing. The ASME B89.4.19-2006 standard for testing laser trackers is briefly presented. The warm-up effect of the instrument is inspected with respect to both angle measurement and distance measurement. The absolute distance meter (ADM) is compared with a laboratory interferometer on a 30-meter long rail and also on a bench with automated movement of the carriage of the reflector. A time series of measurements for determining the additive constant is evaluated. A simple test of the stability of the distance measurement in field conditions is introduced. Most of the tests were carried out at the Research Institute of Geodesy, Topography and Cartography (RIGTC) and at the Faculty of Civil Engineering (FCE) of the Czech Technical University in Prague (CTU).</p>

scholarly journals NEW METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF FEBUXOSTAT IN HUMAN PLASMA BY LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY

2016 ◽  
Vol 8 (9) ◽  
pp. 61 ◽  
Author(s):  
Narottam Pal ◽  
Avanapu Srinivasa Rao ◽  
Pigilli Ravikumar
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Plasma ◽  
Method Development ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
New Method ◽  
Liquid Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry

<p><strong>Objective</strong>:<strong> </strong>To develop a new method and validate the same for the determination of Febuxostat (FBS) in human plasma by liquid chromatography–mass spectrometry (LCMS).</p><p><strong>Methods</strong>:<strong> </strong>The present method utilized reversed-phase high-performance liquid chromatography with tandem mass spectroscopy. Febuxostat D9 (FBS D9) was used as internal standard (IS). The analyte and internal standard were separated from human plasma by using solid phase extraction method. Zorbax Eclipse XDB, C<sub>8</sub>, 100 mm x 4.6 mm, 3.5 µm column was used and HPLC grade acetonitrile, 5 millimolar (mM) ammonium format (80: 20, v/v) as mobile phase, detected by mass spectrometry operating in positive ion and multiple reaction monitoring modes.</p><p><strong>Results</strong>:<strong> </strong>The parent and production transitions for FBS and internal standard were at m/z 317.1→261.0 and 326.1→262.0 respectively. The method was validated for system suitability, specificity, carryover effect, linearity, precision, accuracy, matrix effect, sensitivity and stability. The linearity range was from 20.131 ng/ml to10015. 534 ng/ml with a correlation coefficient of 0.999. Precision results (%CV) across six quality control samples were within the limit. The percentage recovery of FBS and internal standard from matrix samples was found to be 76.57% and 75.03% respectively.</p><p><strong>Conclusion</strong>:<strong> </strong>Present study describes new LC-MS method for the quantification of FBS in a pharmaceutical formulation. According to validation results, it was found to be a simple, sensitive, accurate and precise method and also free from any kind of interference. Therefore the proposed analytical method can be used for routine analysis for the estimation of FBS in its formulation.</p>

Seasonal variation of abscisic acid in the dormant shoots of Douglas-fir

1979 ◽  
Vol 57 (5) ◽  
pp. 534-538 ◽  
Author(s):  
Joe E. Webber ◽  
Murray L. Laver ◽  
Joe B. Zaerr ◽  
Denis P. Lavender
Keyword(s):  
Abscisic Acid ◽  
Liquid Chromatography ◽  
Seasonal Variation ◽  
Internal Standard ◽  
Close Correlation ◽  
Douglas Fir ◽  
Gas Liquid Chromatography ◽  
Bud Burst ◽  
Liquid Chromatography Mass Spectrometry ◽  
Layer Chromatography

The occurrence of abscisic acid (ABA) in the dormant shoots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was confirmed by bioassay, thin-layer chromatography, gas–liquid chromatography, and gas–liquid chromatography – mass spectrometry. Seasonal variation of ABA in the buds, leaves, and stems was then determined using 2-trans-ABA as an internal standard. Concentrations of ABA were highest in the autumn for buds (2.1 μg/g) and needles (0.79 μg/g) and highest in January for stems (0.34 μg/g). The lowest concentrations for all tissues were in February and March, before bud burst. Close correlation of levels of ABA with previously measured physiological evidence of growth and metabolic activity suggests a possible role in the dormancy cycle of Douglas-fir.

scholarly journals Multi-sensor data fusion based on consistency test and sliding window variance weighted algorithm in sensor networks

2013 ◽  
Vol 10 (1) ◽  
pp. 197-214 ◽  
Author(s):  
Jian Shu ◽  
Ming Hong ◽  
Wei Zheng ◽  
Li-Min Sun ◽  
Xu Ge
Keyword(s):  
Sensor Networks ◽  
Internal Noise ◽  
Sliding Window ◽  
Test Method ◽  
Sensor Data ◽  
Data Simulation ◽  
Consistency Test ◽  
Multi Sensor Data Fusion ◽  
Weighted Algorithm ◽  
The Stability

In order to solve the problem that the accuracy of sensor data is reducing due to zero offset and the stability is decreasing in wireless sensor networks, a novel algorithm is proposed based on consistency test and sliding-windowed variance weighted. The internal noise is considered to be the main factor of the problem in this paper. And we can use consistency test method to diagnose whether the mean of sensor data is offset. So the abnormal data is amended or removed. Then, the result of fused data can be calculated by using sliding window variance weighted algorithm according to normal and amended data. Simulation results show that the misdiagnosis rate of the abnormal data can be reduced to 3% by using improved consistency test with the threshold set to [0.05, 0.15], so the abnormal sensor data can be diagnosed more accurately and the stability can be increased. The accuracy of the fused data can be improved effectively when the window length is set to 2. Under the condition that the abnormal sensor data has been amended or removed, the proposed algorithm has better performances on precision compared with other existing algorithms.

Liquid-chromatographic measurement of nitrazepam in plasma.

1982 ◽  
Vol 28 (7) ◽  
pp. 1478-1481 ◽  
Author(s):  
H Kelly ◽  
A Huggett ◽  
S Dawling
Keyword(s):  
Complete Resolution ◽  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Small Sample ◽  
Ultraviolet Detector ◽  
Liquid Chromatographic Method ◽  
Chromatographic Measurement ◽  
The Stability ◽  
Liquid Chromatographic

Abstract In this simple and rapid "high-performance" liquid-chromatographic method for determining nitrazepam in plasma, serum, or whole blood, the sample at pH 7.4 is extracted into diethyl ether with an internal standard (prazepam), chromatographed, and detected at 280 nm with a fixed-wavelength ultraviolet detector. A specimen, together with standards and a quality control, can be analyzed in duplicate within 90 min. The limit of sensitivity is 5 micrograms/L (nitrazepam and 7-acetamidonitrazepam) and 50 micrograms/L (7-aminonitrazepam), and no interferents have been found. This method has the advantages of a small sample requirement and complete resolution of nitrazepam and the above-mentioned major metabolites. We have used this method for analysis of therapeutic and overdose concentrations of nitrazepam, and to investigate the stability of the drug in blood.

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