scholarly journals HPLC Estimation of New Impurity Methyl Ezetimibe in Ezetimibe Drug

2020 ◽  
Vol 32 (6) ◽  
pp. 1309-1313
Author(s):  
Duggirala Parvatha Venkata Vardhani Devi ◽  
Kapavarapu Maruthi Venkata Narayanarao ◽  
Pulipaka Shyamala ◽  
Rallabhandi Murali Krishna ◽  
Komali Siva Prasad
Keyword(s):  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Gradient Elution ◽  
Hplc Method ◽  
The Novel ◽  
Signal To Noise ◽  
Drug Substances ◽  
Chromatographic Detection ◽  
Noise Ratio ◽  
Gradient Elution Mode

A new gradient elution mode HPLC method was developed and validated to detect and monitor the novel impurity namely methyl ezitimibe in ezetimibe drug substances. Chromatographic detection and analysis of methyl ezetimibe was performed on XBridge C18 column with mobile phase consisting of 0.02 M phosphate buffer (pH 5) and acetonitrile with 1 mL/min flow rate in gradient elution mode. Methyl ezetimibe was detected and monitored at 248 nm. The calibration curve was linear over range of 0.015 to 0.219% concentration. The limit of detection and quantification were computed as 0.005% (signal to noise ratio 3.60) and 0.015% (signal to noise ratio 15.96), respectively. The precision was 0.97% (%RSD) and accuracy was 93.2 to 98.2% (recovery). The developed method was proved suitable to detect and monitor methyl ezetimibe impurity in ezetimibe drug substances.

scholarly journals Development, Validation, and Application of HPLC Method for Quantification of Antihyperuricemic Compounds from Lippia nodiflora in Rat Plasma

2019 ◽  
Vol 6 (01) ◽  
pp. e28-e35
Author(s):  
Lee-Chuen Cheng ◽  
Vikneswaran Murugaiyah ◽  
Kit-Lam Chan
Keyword(s):  
Limit Of Detection ◽  
Peak Plasma ◽  
Signal To Noise Ratio ◽  
Rat Plasma ◽  
Hplc Method ◽  
The Body ◽  
The Other ◽  
Aqueous Acetic Acid ◽  
Signal To Noise ◽  
Noise Ratio

AbstractAn HPLC method for simultaneous determination of arenarioside (1 ), verbascoside (2), 6-hydroxyluteolin (3), 6-hydroxyluteolin-7-O-glycoside (4), and nodifloretin (5) from Lippia nodiflora in rat plasma was developed and validated. The optimal chromatographic separation was achieved with a gradient mobile phase comprising 0.1% aqueous acetic acid and acetonitrile. The limit of detection was 78.1 ng/mL for 3 and 39.1 ng/mL for the other compounds (signal-to-noise ratio=3), whereas the limit of quantification was 312.5 ng/mL for 3 and 156.3 ng/mL for the other compounds (signal-to-noise ratio=12). The recovery values of compounds 1–5 ranged from 89.37–100.92%. Their accuracy values were between 96.48 and 105.81%, while their corresponding precision values were in the range of 0.75–9.06% for both intraday and inter-day analysis. The method was then applied in the first pharmacokinetic study of 1–5. Following intravenous administration, 1–5 were eliminated slowly from the body with a mean clearance value of 0.11, 0.13, 0.30, 0.09, and 0.23 L/kg h, respectively. Meanwhile, their peak plasma concentration upon oral administration was 8.97, 1.07, 1.06, 0.65, and 0.38 µg/mL, respectively. Compound 3 (5.97%) exhibited the highest absolute oral bioavailability value, followed by 1 (5.22%), 4 (3.13%), 2 (2.10%), and 5 (0.93%).

scholarly journals Eddy-covariance data with low signal-to-noise ratio: time-lag determination, uncertainties and limit of detection

2015 ◽  
Vol 8 (3) ◽  
pp. 2913-2955 ◽  
Author(s):  
B. Langford ◽  
W. Acton ◽  
C. Ammann ◽  
A. Valach ◽  
E. Nemitz
Keyword(s):  
Eddy Covariance ◽  
Random Error ◽  
Limit Of Detection ◽  
Sampling Error ◽  
Signal To Noise Ratio ◽  
Time Lag ◽  
Systematic Bias ◽  
Signal To Noise ◽  
Cross Covariance ◽  
Noise Ratio

Abstract. All eddy-covariance flux measurements are associated with random uncertainties which are a combination of sampling error due to natural variability in turbulence and sensor noise. The former is the principal error for systems where the signal-to-noise ratio of the analyser is high, as is usually the case when measuring fluxes of heat, CO2 or H2O. Where signal is limited, which is often the case for measurements of other trace gases and aerosols, instrument uncertainties dominate. We are here applying a consistent approach based on auto- and cross-covariance functions to quantifying the total random flux error and the random error due to instrument noise separately. As with previous approaches, the random error quantification assumes that the time-lag between wind and concentration measurement is known. However, if combined with commonly used automated methods that identify the individual time-lag by looking for the maximum in the cross-covariance function of the two entities, analyser noise additionally leads to a systematic bias in the fluxes. Combining datasets from several analysers and using simulations we show that the method of time-lag determination becomes increasingly important as the magnitude of the instrument error approaches that of the sampling error. The flux bias can be particularly significant for disjunct data, whereas using a prescribed time-lag eliminates these effects (provided the time-lag does not fluctuate unduly over time). We also demonstrate that when sampling at higher elevations, where low frequency turbulence dominates and covariance peaks are broader, both the probability and magnitude of bias are magnified. We show that the statistical significance of noisy flux data can be increased (limit of detection can be decreased) by appropriate averaging of individual fluxes, but only if systematic biases are avoided by using a prescribed time-lag. Finally, we make recommendations for the analysis and reporting of data with low signal-to-noise and their associated errors.

Determination of trans-phylloquinone in children's serum.

1989 ◽  
Vol 35 (5) ◽  
pp. 874-878 ◽  
Author(s):  
F Moussa ◽  
L Dufour ◽  
J R Didry ◽  
P Aymard
Keyword(s):  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Fluorometric Detection ◽  
Vitamin K1 ◽  
Signal To Noise ◽  
Détection Signal ◽  
Coagulation Tests ◽  
Noise Ratio ◽  
Detection Signal

Abstract By optimizing the conditions for determining trans-phylloquinone and its metabolite, K-2,3-epoxide, in serum through a two-step HPLC process combined with fluorometric detection after coulometric reduction, we have been able to develop a method applicable to small volumes of serum (200 to 500 microL). The limit of detection (signal-to-noise ratio of 3) was 15 ng/L for trans-phylloquinone, 30 ng/L for K-2,3-epoxide. The trans-phylloquinone concentrations measured by this method in serum from 82 children, ages one to six years, whose results were normal for overall coagulation tests, ranged from 40 to 880 ng/L (median 175 ng/L). We discuss these findings and compare them with vitamin K1(20) values reported for adults.

In-Parallel Passive Compliant Coupler for Robot Force Control

2000 ◽  
Author(s):  
T. A. Dwarakanath ◽  
Carl D. Crane ◽  
Joseph Duffy ◽  
Chad Tyler
Keyword(s):  
Mechanism Design ◽  
Force Control ◽  
Parallel Mechanism ◽  
Quality Index ◽  
Compliant Mechanism ◽  
Signal To Noise Ratio ◽  
The Novel ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Novel Design

Abstract This paper describes the design of a Passive Compliant Coupler for Force Control (PCCFC) based on an in-parallel mechanism. The optimal synthesis of the mechanism is performed with the objective of achieving a good quality index. The novel design of the connector (also termed as the leg), a crucial element of the mechanism, is one of the important features of the paper. The shape optimization of connectors of an in-parallel mechanism is obtained by satisfying compliant requirements and considering maximization of signal to noise ratio criteria. The various design aspects of sizing, sensing the displacement, and implementation of the connector are discussed. The in-parallel compliant mechanism for force control is obtained by optimizing the signal to noise ratio at various stages of the mechanism design.

scholarly journals Eddy-covariance data with low signal-to-noise ratio: time-lag determination, uncertainties and limit of detection

2015 ◽  
Vol 8 (10) ◽  
pp. 4197-4213 ◽  
Author(s):  
B. Langford ◽  
W. Acton ◽  
C. Ammann ◽  
A. Valach ◽  
E. Nemitz
Keyword(s):  
Eddy Covariance ◽  
Random Error ◽  
Limit Of Detection ◽  
Sampling Error ◽  
Signal To Noise Ratio ◽  
Time Lag ◽  
Systematic Bias ◽  
Signal To Noise ◽  
Cross Covariance ◽  
Noise Ratio

Abstract. All eddy-covariance flux measurements are associated with random uncertainties which are a combination of sampling error due to natural variability in turbulence and sensor noise. The former is the principal error for systems where the signal-to-noise ratio of the analyser is high, as is usually the case when measuring fluxes of heat, CO2 or H2O. Where signal is limited, which is often the case for measurements of other trace gases and aerosols, instrument uncertainties dominate. Here, we are applying a consistent approach based on auto- and cross-covariance functions to quantify the total random flux error and the random error due to instrument noise separately. As with previous approaches, the random error quantification assumes that the time lag between wind and concentration measurement is known. However, if combined with commonly used automated methods that identify the individual time lag by looking for the maximum in the cross-covariance function of the two entities, analyser noise additionally leads to a systematic bias in the fluxes. Combining data sets from several analysers and using simulations, we show that the method of time-lag determination becomes increasingly important as the magnitude of the instrument error approaches that of the sampling error. The flux bias can be particularly significant for disjunct data, whereas using a prescribed time lag eliminates these effects (provided the time lag does not fluctuate unduly over time). We also demonstrate that when sampling at higher elevations, where low frequency turbulence dominates and covariance peaks are broader, both the probability and magnitude of bias are magnified. We show that the statistical significance of noisy flux data can be increased (limit of detection can be decreased) by appropriate averaging of individual fluxes, but only if systematic biases are avoided by using a prescribed time lag. Finally, we make recommendations for the analysis and reporting of data with low signal-to-noise and their associated errors.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

Speech Reception in the Presence of Classroom Noise

1979 ◽  
Vol 10 (4) ◽  
pp. 221-230 ◽  
Author(s):  
Veronica Smyth
Keyword(s):  
Signal To Noise Ratio ◽  
Learning Processes ◽  
Speech Discrimination ◽  
Signal To Noise ◽  
Speech Reception ◽  
Monosyllabic Words ◽  
Noise Ratio

Three hundred children from five to 12 years of age were required to discriminate simple, familiar, monosyllabic words under two conditions: 1) quiet, and 2) in the presence of background classroom noise. Of the sample, 45.3% made errors in speech discrimination in the presence of background classroom noise. The effect was most marked in children younger than seven years six months. The results are discussed considering the signal-to-noise ratio and the possible effects of unwanted classroom noise on learning processes.

Sign in / Sign up

Export Citation Format

Share Document