A NEW METHOD FOR THE DETERMINATION OF THE MOLECULAR WEIGHT OF THE PROTEINS

1926 ◽  
Vol 48 (2) ◽  
pp. 430-438 ◽  
Author(s):  
The Svedberg ◽  
Robin Fåhraeus
Keyword(s):  
Molecular Weight ◽  
New Method

A New Method for the Sequence Determination of a Peptide Mixture through Molecular Weight Measurements by Mass Spectrometry

1980 ◽  
Vol 28 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Takekiyo Matsuo ◽  
Itsuo Katakuse ◽  
Hisashi Matsuda ◽  
Yasutsugu Shimonishi ◽  
Yeong-Man Hong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Molecular Weight ◽  
New Method ◽  
Sequence Determination ◽  
Peptide Mixture

Characterization of Petroleum Sulfonates by a Nonaqueous Titration Method

1981 ◽  
Vol 21 (06) ◽  
pp. 771-778 ◽  
Author(s):  
Kim R. Voss ◽  
Clark E. Bricker ◽  
M.J. Michnick ◽  
G.P. Willhite
Keyword(s):  
Molecular Weight ◽  
Interfacial Tension ◽  
Oil Recovery ◽  
Perchloric Acid ◽  
Molecular Species ◽  
New Method ◽  
Equivalent Weight ◽  
Petroleum Sulfonate ◽  
Wet Ashing

Summary A new method is described for the determination of the equivalent weight for petroleum sulfonates. The method is based on the direct acidimetric titration of the sulfonate in acetic acid/acetic anhydride solvent using a titrant of perchloric acid in dioxane. From the titration, the moles of perchloric acid required to react with the sulfonate is measured. The equivalent weight is calculated from the grams of sample titrated and the moles of acid used. The potentiometric titration can be carried out in less than 10 minutes and can be done with 10 to 100 mg of sample. The accuracy and precision of the procedure were examined by the titration of sodium salts of p-toleuene sulfonate, 2-naphthalene sulfonate, and petroleum sulfonates. In general, values for the equivalent weight were within 2% of those values determined by the Epton titration, by wet ashing methods, or from the theoretical value. The relative standard deviation (RSD) for the procedure is estimated to be 0.5%. For p-toluene sulfonate, an RSD of 0.15% was calculated. The new method was used to determine the equivalent weights for three fractions of a petroleum sulfonate obtained by the preferential elution from silica gel with alcohol. A series of samples with varying equivalent weight was prepared by proportional combination of the three fractions. Analysis by high-performance liquid chromatography (HPLC) gave a set of data points of peak areas for the series. A plot of equivalent weight as a function of disulfonate to total peak area ratio resulted in a straight line. The slope of this line is descriptive of the molecular weight range for the petroleum sulfonate. Introduction Petroleum sulfonates are used to liberate a residual oil from a porous medium in a tertiary oil-recovery process. One mechanism for the release of oil is the reduction of the interfacial tension between water and oil to values on the order of 10−3 dyne/cm.1–5 The performance of a sulfonate as a surfactant depends on its molecular size and structure. For a pure single-species sulfonate, these properties can be correlated with the alteration of the interfacial tension between water and oil. The same cannot be done for a petroleum sulfonate because the sulfonate is a mixture of molecular species with unknown structures. Previous studies6,7 have shown that the overall composition of a petroleum sulfonate is altered by the preferential partitioning of the molecular species to the oil, water, and rock phases. This causes the composition of the sulfonate to change constantly as it flows through the porous media contacting water and oil. To correlate oil-recovery efficiency with a property of the sulfonate, analytical methods are needed to characterize the effluent from core floods. One parameter for characterizing petroleum sulfonates is the average equivalent weight, which is the weight in grams containing 1 mol of sulfonate functional groups. Sufficient sample is often not available for the equivalent weight analysis by the ASTM wet ashing procedure, and the oil in the sample may often interfere with the Epton titrate method. Therefore, a study was initiated to develop a method for the determination of equivalent weight of petroleum sulfonates in the 10- to 100-mg range. Of equal importance is a method to count sulfonate groups and to differentiate mono- and disulfonate molecules. The latter can be achieved by HPLC using an anion exchange column.8 However, quantification of the effluent from the HPLC column remains a problem. No detector is available that responds specifically to the sulfonate functional group -SO3−. Specific ion-electrodes of the liquid- or solid-membrane type show varying response to sulfonates depending on the molecular weight of the sulfonate.9,10

A new method for the determination of nitrates

1960 ◽  
Vol 23 ◽  
pp. 227-232 ◽  
Author(s):  
P WEST ◽  
G LYLES
Keyword(s):  
New Method

A New Method for the Determination of Plasma Activators of Fibrinolysis

1977 ◽  
Vol 37 (02) ◽  
pp. 210-215 ◽  
Author(s):  
R Margalit ◽  
E Gidron ◽  
Y Shalitin
Keyword(s):  
New Method ◽  
Effective Activator

SummaryThe term “effective activator” of plasminogen is proposed, to denote the resultant of activator-antiactivator interaction, and a method for the determination of the level of these activators is described. By adding axcess plasminogen to the euglobulin fraction of plasma the influence of the level of endogenous plasminogen and of the antiplasmin is eliminated. It is shown that the level of fibrinogen has very little bearing on the results. An effective activator unit is defined as equal to 1 CTA unit of urokinase activity on a fibrinogen-plasminogen substrate.

The Plasmin Inhibitors of Plasma

1964 ◽  
Vol 12 (01) ◽  
pp. 119-125 ◽  
Author(s):  
Y Shamash ◽  
A Rimon
Keyword(s):  
Human Plasma ◽  
New Method ◽  
Normal Amount ◽  
Caseinolytic Activity ◽  
Before And After ◽  
Plasmin Inhibitors

SummaryA new method for the assay of plasmin inhibitors in human plasma is described. The method consists of determination of the caseinolytic activity of a standard plasmin solution before and after incubation with the inhibitor, with lysine added to the mixture as a stabilizer of plasmin. Using this method, it was found that plasma contains enough inhibitors to inactivate 30 caseinolytic units of plasmin, or 10 times the normal amount of plasminogen in human plasma.

AGGLUTINATION INHIBITION REACTIONS FOR THE DETERMINATION OF GONADOTROPHINS

1969 ◽  
Vol 62 (1_Suppl) ◽  
pp. S95-S112 ◽  
Author(s):  
A. H. W. M. Schuurs
Keyword(s):  
Immune System ◽  
Quantitative Determination ◽  
Haemagglutination Inhibition ◽  
Latex Agglutination ◽  
Literature Survey ◽  
New Method ◽  
Test Fluid ◽  
Main Application ◽  
Test Systems

ABSTRACT Various techniques for sensitising erythrocytes and latex particles with gonadotrophins, particularly with HCG, are described. The haemagglutination inhibition reactions are generally interpreted by means of »erythrocyte settling patterns«. By a new method of evaluating these patterns a relatively precise quantitative determination is possible. Latex agglutination inhibition reactions on slides are particularly suitable as rapid qualitative tests. In cases where the maximum attainable sensitivity of the agglutination inhibition tests is insufficient, e. g. for determining LH concentrations in urine, the hormone in the test fluid has to be concentrated or extracted. An alternative method is a modified haemagglutination inhibition test for large volumes which is applicable to unconcentrated urine. Due to non-specific inhibitions the above-mentioned tests cannot be applied to unprocessed serum. Agglutination inhibition tests with HCG are already well advanced, pregnancy diagnosis being their main application. Now that highly purified HCG is available, a satisfactory specificity for these tests can be attained. If the immune system for HCG is used for estimating LH, it has to meet additional specificity requirements. Furthermore, the measure of cross-reaction and the choice of standard merit special attention. Finally, a literature survey is given of test systems in which LH and FSH were used as antigens.

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