Determination of the molar absorptivity of NADH.

1976 ◽  
Vol 22 (2) ◽  
pp. 141-150 ◽  
Author(s):  
R B McComb ◽  
L W Bond ◽  
R W Burnett ◽  
R C Keech ◽  
G N Bowers
Keyword(s):  
Systematic Error ◽  
Standard Error ◽  
High Purity ◽  
Molar Absorptivity ◽  
Average Value ◽  
Effects Of Ph ◽  
The Mean ◽  
Ph Buffer ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract The molar absorptivity of NADH at 340 nm has been determined by an indirect procedure in which high-purity glucose is phosphorylated by ATP in the presence of hexokinase, coupled to oxidation of the glucose-6-phosphate by NAD+ in the presence of glucose-6-phosphate dehydrogenase. The average value from 85 independent determinations is 6317 liter mol-1 cm-1 at 25 degrees C and pH 7.8. The overall uncertainty is -4.0 to +5.5 ppt (6292 to 6352 liter mol-1 cm-1), based on a standard error of the mean of 0.48 ppt and an estimate of systematic error of -2.6 to +4.1 ppt. Effects of pH, buffer, and temperature on the molar absorptivity are also reported.

The determination of the cross sections for the reactions 27 Al( n , α ) and 56 Fe( n , p ) for 14 MeV neutrons by an absolute method

1966 ◽  
Vol 292 (1429) ◽  
pp. 180-192 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Standard Error ◽  
Particle Method ◽  
Systematic Errors ◽  
Aluminium Foil ◽  
The Mean ◽  
The Cross ◽  
Experimental Values

Measurements of the cross sections for the reactions 27 Al( n , α ) 24 Na and 56 Fe( n, p ) 56 Mn for neutrons of energy 13.5 ± 0.1 MeV have been made by a radioactivation method. The neutron flux was determined by a variant of the 'associated particle’ method, in which the α -particles produced concurrently with the neutrons from the D + T reaction were estimated in terms of the volume of helium which accumulated when they were brought to rest in an aluminium foil. Cross section values obtained at 13.5 MeV were: for 27 Al( n , α ): 118.1 ± 6.0 mb : for 56 Fe( n, p ): 106.7 ± 4.7 mb. The errors quoted include both the standard error on the mean of the experimental values and an estimate of possible residual systematic errors. The excitation functions for both reactions in the energy region 13.5 to 14.8 MeV have also been investigated, in order to provide secondary cross section values over this range of energies. At 14.8 MeV the values found were: 27 Al( n , α )103.6 ± 5.5 mb; 56 Fe( n, p )96.7 ± 4.5 mb.

scholarly journals Hipparcos, Three Years After Launch

1993 ◽  
Vol 156 ◽  
pp. 1-10
Author(s):  
J. Kovalevsky ◽  
M. Froeschlé
Keyword(s):  
Standard Error ◽  
Present Status ◽  
Double Star ◽  
New Method ◽  
Standard Errors ◽  
First Year ◽  
Mass Determination ◽  
Mission Duration ◽  
The Mean

In a first part, the present status of the HIPPARCOS mission is described. Despite the degradations and failures of gyroscopes, it is still hoped that a 4 1/2 mission duration will be reached. The first-year of data has been reduced by both FAST and NDAC consortia. For the best 46200 observed stars, the distribution of standard errors in positions has a maximum of 1.5 mas in latitude and 1.8 mas in longitude and the mean standard error for parallaxes is of the order of 3 mas. The comparison of results obtained by both consortia shows that the differences are small and quite consistent with the announced internal precisions. Magnitude measurements are precise to 0.02 magnitude for a 4 second observation. The precision to be expected for double star observations is also given. The main new result is that the magnitudes of the components are obtained with a few hundredths of a magnitude precision. This allows to devise a new method of mass determination based upon the parallax and a recalibrated mass-luminosity diagram. The parallax dependence of the results is much more favourable than in the case of the classical determination of masses using orbital motions.

EVALUATION OF FLAME PHOTOMETRIC DETERMINATION OF MAGNESIUM IN PLANT MATERIAL

1964 ◽  
Vol 44 (6) ◽  
pp. 520-524
Author(s):  
A. A. MacLean
Keyword(s):  
Standard Error ◽  
Plant Material ◽  
Photometric Determination ◽  
Flame Photometry ◽  
Mean Values ◽  
Edta Titration ◽  
The Mean ◽  
Flame Method ◽  
Oxyhydrogen Flame

Flame methods for the determination of magnesium in plant material were compared with EDTA titration and a thiazole yellow procedure. Mean values for quadruplicate determinations on 24 samples were 0.544, 0.543, 0.532, and 0.514% for EDTA, flame photometry with an oxyhydrogen flame, thiazole yellow, and flame photometry with an oxyacetylene flame respectively.The degree of precision, as indicated by the standard error of the mean, was highest for the oxyhydrogen flame method and lowest when the oxyacetylene flame was used.Silica repressed magnesium emission with either flame source but degree of interference was greater with the oxyhydrogen flame.

scholarly journals Spectrophotometric Determination of Organic Nitrogen by a Modified Lassaigne Method and Its Application to Meat Products and Baby Food

2002 ◽  
Vol 85 (4) ◽  
pp. 971-977 ◽  
Author(s):  
Birsen Demirata ◽  
Resat Apak ◽  
Hüseyin Afsar ◽  
Izzet Tor
Keyword(s):  
Meat Products ◽  
Molar Absorptivity ◽  
Baby Food ◽  
Protein Nitrogen ◽  
Colorimetric Measurement ◽  
Total Digestion ◽  
Kjeldahl Method ◽  
The Mean ◽  
Aqueous Leachate

Abstract A modified Lassaigne method was developed for N determination based on fusion of the organic substance with metallic Na, conversion of the cyanide in the aqueous leachate to thiocyanate by ammonium polysulfide treatment, and colorimetric measurement of the thiocyanate formed by the addition of excessive ferric ions in acidic medium. The mean molar absorptivity of the Fe(NCS)2+ complex at 480 nm is 2.96 × 103 L/mol·cm, enabling quantitation of 0.25–7.72 ppm N (linear range) in the final solution. The relative amounts of Na, (NH4)2S2, and Fe(III) with respect to nitrogen in the analyte were optimized. The developed method was successfully applied to the determination of N in various brands of baby food, and it was compared statistically with the conventional Kjeldahl and elemental analysis methods. Protein nitrogen in a number of meat products was also precisely determined by the developed method. Thus, the total digestion time of the conventional Kjeldahl method was reduced considerably (e.g., to approximately 15 min for a dried sample) with a relatively simple spectrophotometric method requiring no sophisticated instrumentation.

scholarly journals Spectrophotometric Methods for the Assay of Fluvoxamine Using Chromogenic Reagents

2010 ◽  
Vol 7 (4) ◽  
pp. 1539-1545
Author(s):  
V. Annapurna ◽  
G. Jyothi ◽  
V. Nagalakshmi ◽  
B. B. V. Sailaja
Keyword(s):  
Ascorbic Acid ◽  
Regression Analysis ◽  
Standard Error ◽  
Oxidative Coupling ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Method Of Least Squares ◽  
Spectrophotometric Methods ◽  
Uv Visible

Simple, accurate and reproducible UV-Visible spectrophotometric methods were established for the assay of FXA based on the oxidative coupling and condensation reactions. Condensation and coupling of the FXA with Ninhydrin-Ascorbic acid is proposed in method A. Method B includes complexation of FXA with cobalt thiocyanate. The ligating property of FXA with sodium nitro prusside is incorporated in method C. The optical characteristics such as Beers law limits, molar absorptivity and Sandell’s sensitivity for the methods (A-C) are given. Regression analysis using the method of least squares was made to evaluate the slope(b), intercept(a) and correlation coefficient (r) and standard error of estimation (Se) for each system. Determination of FXA in bulk form and in pharmaceutical formulations were also incorporated.

scholarly journals Solvent Extraction of Thorium Using 5,11,17,23-Tetra[(2-ethyl acetoethoxyphenyl)(azo)phenyl]calix[4]arene

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Quang Hieu Tran ◽  
Van Tan Le ◽  
Van Cuong Nguyen
Keyword(s):  
Aqueous Solution ◽  
Solvent Extraction ◽  
Molar Absorptivity ◽  
Tolerance Limits ◽  
Acidic Aqueous Solution ◽  
Selective Method ◽  
Chloroform Layer ◽  
Effects Of Ph ◽  
Synthetic Solution

A rapid, sensitive, and selective method for determination of thorium based on the complex withortho-ester tetra-azophenylcalix[4]arene (TEAC) was described. In the presence of pH of 4–6, TEAC-Th(IV) complex is extracted from an acidic aqueous solution into chloroform layer. The absorbance intensity of complex was measured by UV-Vis spectrometer at 525 nm and the molar absorptivity was found to be 2.4 × 104. Beer’s law was obeyed in the range of 1.0 to 25 × 10−5 M thorium(IV). The effects of pH, TEAC concentration, and shaking time were also studied. The tolerance limits for several metal ions were calculated. The proposed method was applied to the determination of thorium in synthetic solution and in the monazite sand samples with good results.

scholarly journals Spectrophotometric Determination of Various Drugs Using Chloranilic Acid as Chromogenic Reagent - II

2010 ◽  
Vol 7 (2) ◽  
pp. 624-628 ◽  
Author(s):  
V. Annapurna ◽  
G. Jyothi ◽  
T. Rohini Kumari ◽  
B. B. V. Sailaja
Keyword(s):  
Regression Analysis ◽  
Charge Transfer ◽  
Spectrophotometric Method ◽  
Standard Error ◽  
Redox Reaction ◽  
Charge Transfer Complex ◽  
Molar Absorptivity ◽  
Method Of Least Squares ◽  
Chloranilic Acid

Simple, accurate and reproducible visible spectrophotometric method for the assay of drugs such as pyrilamine and fluvoxamine as maleates was established based on the formation of charge-transfer complex and redox reaction between the corresponding drug and substitutedp-benzoquinone (chloranilic acid). The optical characteristics such as Beer’s law limits, molar absorptivity and Sandell’s sensitivity are reported. Regression analysis using the method of least squares was made to evaluate the slope (b), intercept (a) and correlation coefficient (r) and standard error of estimation (Se) for each drug.

24-Hour Dialysate Collection for Determination of Peritoneal Membrane Transport Characteristics: Longitudinal Follow-Up Data for the Dialysis Adequacy and Transport Test (Datt)

1996 ◽  
Vol 16 (6) ◽  
pp. 590-593 ◽  
Author(s):  
Michael V. Rocco ◽  
Jean R. Jordan ◽  
John M. Burkart
Keyword(s):  
Peritoneal Dialysis ◽  
Membrane Transport ◽  
Standard Error ◽  
Peritoneal Membrane ◽  
Dialysis Adequacy ◽  
Peritoneal Transport ◽  
The Mean ◽  
Cr Concentration ◽  
Over Time

Objective To determine the ability of the dialysis adequacy and transport test (DATT) to monitor changes in peritoneal transport characteristics over time. Setting University-based peritoneal dialysis program. Patients One hundred patients on continuous ambulatory peritoneal dialysis who underwent 226 simultaneous DATTs and peritoneal equilibration tests (PET). Methods Retrospective analysis of DA TT and PET data. Results The mean 24-hour dialysate-to-plasma creatinine (cr) concentration ratio (DIP cr) from the DATT was 0.70±0.10, and the mean four-hour DIP crfrorn the PET was 0.68 ± 0.10. The correlation coefficient between the fourhour and 24-hour DIP cr was 0.81, and the standard error of estimate was 0.065. The mean (±SD) difference between the four-hour and 24-hour DIP cr was 0.023 ± 0.061. Fifty eight patients had two or more sequential DA TTs and PETs. For these 94sets of sequential DATTs and PETs, the mean (±SD) difference between the change in the four-hour DIP cr and the change in the 24-hour DIP cr was 0.020 ± 0.024, and the standard error of estimate was 0.064. In 17 patients a change in dwell volume from 2.0 L to 2.5 L occurred between the first and second measures of peritoneal membrane transport characteristics. The mean (±SD) difference between the change in the four-hour DIP cr and the change in the 24-hour DIP cr was 0.036 ± 0.055, and the standard error of estimate was 0.087. Conclusion The DATT can be used to monitor for changes in peritoneal transport over time. It should not be used in patients receiving cycler therapy or in patients whose dwell times and dextrose concentrations vary markedly from day to day.

A determination of the frictional forces in a tidal current

1952 ◽  
Vol 214 (1118) ◽  
pp. 371-392 ◽  
Keyword(s):  
Frictional Force ◽  
Tidal Current ◽  
Frictional Stress ◽  
Dynamical Equations ◽  
Average Value ◽  
Open Sea ◽  
Frictional Forces ◽  
The Mean ◽  
Mean Current

The frictional forces in a tidal current have been determined from simultaneous observations of the surface gradients and the currents at various depths. The observations were made a few miles from the coast, off Red Wharf Bay, Anglesey. The gradients were derived from measurements of the surface elevations obtained by a pair of open-sea tide-gauges of the Favé type, modified to give increased accuracy. The Doodson electrically recording current meter was used for the current measurements. Each set of observations extended over 24 h, and they were subjected to harmonic analysis for the semi-diurnal constituent. The data from these analyses were then used in the dynamical equations, giving the amplitudes and phases of the frictional force at the bottom, and of the internal shearing stress in the water at various depths. Five complete sets of records were obtained, three of which are considered to have given significant results. Expressing the amplitude of the frictional force at the bottom in the form F ═ kρU 2 , where U is the amplitude of the mean current from surface to bottom, and ρ is the density of the water, the results give the coefficient k an average value of 1⋅8 x 10 ─a . The internal frictional stress in the water was found to increase approximately linearly with depth from the surface to the bottom, and the corresponding values of the mean eddy viscosity have been derived.

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