Perchloric acid procedure for wet-ashing organics for the determination of mercury (and other metals)

1974 ◽  
Vol 46 (11) ◽  
pp. 1606-1609 ◽  
Author(s):  
Cyrus. Feldman
Keyword(s):  
Perchloric Acid ◽  
Wet Ashing

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

Deproteinizing methods evaluated for determination of uric acid in serum by reversed-phase liquid chromatography with ultraviolet detection.

1987 ◽  
Vol 33 (8) ◽  
pp. 1427-1430 ◽  
Author(s):  
R Sakuma ◽  
T Nishina ◽  
M Kitamura
Keyword(s):  
Uric Acid ◽  
Liquid Chromatography ◽  
Perchloric Acid ◽  
High Performance ◽  
Reversed Phase ◽  
Precipitation Method ◽  
Zinc Hydroxide ◽  
Good Precision ◽  
Ultraviolet Detection

Abstract We evaluated six deproteinizing methods for determination of uric acid in serum by "high-performance" liquid chromatography with ultraviolet detection: those involving zinc hydroxide, sodium tungstate, trichloroacetic acid, perchloric acid, acetonitrile, and centrifugal ultrafiltration (with Amicon MPS-1 devices). We used a Toyosoda ODS-120A reversed-phase column. The mobile phase was sodium phosphate buffer (40 mmol/L, pH 2.2) containing 20 mL of methanol per liter. Absorbance of the eluate was monitored at 284 nm. The precipitation method with perchloric acid gave high recoveries of uric acid and good precision, and results agreed with those by the uricase-catalase method of Kageyama (Clin Chim Acta 1971;31:421-6).

The Perchloric Method for the Determination of Sulfur in Rubber

1934 ◽  
Vol 7 (4) ◽  
pp. 730-735
Author(s):  
Ernest Kahane
Keyword(s):  
Nitric Acid ◽  
Perchloric Acid ◽  
Organic Substance ◽  
Present Author ◽  
General Idea ◽  
Organic Substances ◽  
Gutta Percha ◽  
Higher Temperature ◽  
As If

Abstract The problem of the determination of sulfur in rubber has been dealt with extensively in the literature, and it seems as if discussions and descriptions of new technic are nowhere nearly ended yet. The determination is so essential, and its rapid and precise execution is of such importance in industrial technic, that efforts in this direction should not be regarded as wasted. In 1926 and in 1927 Le Caoutchouc et La Gutta-Percha contained two articles in which the present author discussed the conditions of the determination of sulfur in rubber and then proposed the use of a new oxidizing mixture, not mentioned previous to that time, which involved the destruction of organic substances by perchloric acid. This method consisted simply in the attack on a 1-gram sample of rubber by 10 cc. of nitric acid (d. 1.39) and 5 cc. of perchloric acid (d. 1.61). Upon heating, attack by the nitric acid takes place, and this is followed by evaporation of the excess nitric acid, then at a little higher temperature there is an attack by the perchloric acid, which oxidizes the rest of the organic substance completely. This publication was concerned much more, in the determination of sulfur by the perchloric method, with the general idea of the destruction of organic substances than it was with the precise details of carrying it out. The technic had been studied somewhat superficially, as is shown by the text of the article itself.

Fluorometric and Spectrophotometric Determination of Pirbuterol Hydrochloride in Authentic and Dosage Forms

1985 ◽  
Vol 68 (6) ◽  
pp. 1222-1225
Author(s):  
Mohamed E Mohamed ◽  
Hassan Y Aboul-Enein
Keyword(s):  
Potentiometric Titration ◽  
Alkaline Medium ◽  
Spectrophotometric Determination ◽  
Fluorescence Intensity ◽  
Perchloric Acid ◽  
Authentic Sample ◽  
Dosage Forms ◽  
Fluorometric Method ◽  
The Mean

Abstract Pirbuterol hydrochloride has been assayed in alkaline medium by using a fluorometric method to measure fluorescence intensity at 372 nm with excitation at 310 nm and by the ▵A method at 242 nm.The linearity ranges are 0.5-4 μg/mL and 10-50 μg/mL, respectively. An authentic pirbuterol HC1 sample was analyzed by nonaqueous potentiometric titration using 0.1N perchloric acid, and the results were compared with those for fluorometric and AA methods. The mean percent recoveries for the authentic sample were 98.72 ± 1.13 and 99.24 ± 0.85, respectively. When applied to commercial capsules containing 10 mg and 15 mg each, the fluorometric method gave mean percent recoveries of 101.11 ± 1.05 and 98.12 ± 0.93; the ▵A method gave mean percent recoveries of 100.57 ± 0.83 and 97.80 ± 0.75, respectively.

X-Ray Spectroscopy in the Clinical Laboratory

1961 ◽  
Vol 7 (2) ◽  
pp. 115-129 ◽  
Author(s):  
Samuel Natelson ◽  
Bertrum Sheid
Keyword(s):  
Total Phosphorus ◽  
Whole Blood ◽  
Phosphorus Content ◽  
Clinical Laboratory ◽  
Total Iron ◽  
Mean Values ◽  
X Ray ◽  
Significant Difference ◽  
Wet Ashing

Abstract X-ray spectroscopy was applied to the determination of the total phosphorus content of serum and the iron content of whole blood (hemoglobin). Samples were placed on confined spots on paper, dried, then passed through the X-ray field. Concentration was then determined from the peaks as drawn on a recorder. A device is described that permits automatic assay of successive samples dried on paper without delays between readings. Samples are placed in the field and rapidly withdrawn at 30-sec. intervals, the response of the recorder serving as a measure of concentration. Results for total phosphorus in serum and total iron in whole blood were compared with those obtained by a wet ashing procedure. No significant difference with respect to both mean values and precision was observed except that total iron by the wet ashing procedure was more precise. However, the X-ray technic was adequate for clinical purposes. Hemoglobin levels calculated from whole-blood iron values demonstrated that bilirubin, red cell debris, leukocytes, and lipids interfered in the colorimetric but not in the X-ray procedure. A hemoglobinometer based on the X-ray spectroscopic technic may, therefore, yield results of greater clinical significance.

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