Shinichiro Yamaguchi

Microcomputer-aided high-speed potentiometric titration system by linear titration plots

ZusammenfassungDer Aufbau des Geräts wird beschrieben und seine Vorzüge werden diskutiert. Die Zugabe des Titrationsmittels erfolgt stufenweise in großen Anteilen. Die optimalen Volumina werden automatisch je nach Konzentration von einem Mikrocomputer bestimmt. Die Zeitintervalle zwischen den Zugaben werden so gesteuert, daß jeweils nach Gleichgewichtseinstellung der Elektrode eine neue Zugabe erfolgt. Aufgrund linearer Eichkurven erfolgt die online Berechnung des Äquivalenzvolumens, wobei nur vier Titrationspunkte vor dem Äquivalenzpunkt verwendet werden. Mit Hilfe des Gerätes können starke und schwache monoprotische Säuren in weniger als 22 s mit einer relativen Standardabweichung von 0,1–0,2% bestimmt werden.SummaryAn apparatus for high-speed potentiometric titration was assembled and its advantage was demonstrated. Titrant additions were made stepwise in large volumes. The optimum increment volumes were automatically chosen by microcomputer, depending upon the sample concentration. Time intervals between the successive additions were controlled so as to add a new increment immediately after the electrode was equilibrated. On-line calculation of the equivalence volume was conducted based upon linear titration plots, using only four titration points before the equivalence point. The apparatus was capable of determining the concentration of strong and weak monoprotic acids in less than 22s with relative standard deviations of 0.1–0.2%.

High performance liquid chromatographic determination of sodium sulfate in anionic surfactants

Sodium sulfate is separated from anionic surfactants on a separation column packed with strong anion exchange resin, and is detected by a post column derivatization method based on a chemical reaction between sulfate and ferric ion. A calibration curve shows a linear relationship in the range of 10\s-300 mg/100 mL for sodium sulfate. The lower limit of determination is 2 mg/100 mL. Anionic surfactants such as sodium alkylbenzene sulfonate and sodium alkyl sulfate do not interfere with the determination. A personal computer was connected to the chromatographic system for data processing and control of an automatic sampler. This personal computer controlled liquid chromatographic system provides good recovery, reproducibility, agreement with conventional methods and full automatic determination.

Nonaqueous titrimetric analysis of sulfuric and alkylbenzene sulfonic acids in detergent intermediates

A single differential nonaqueous titration method is presented for the analysis of sulfuric and alkylbenzene sulfonic acids in a detergent intermediate material. The organic and sulfuric acids in the sample were quantitatively titrated potentiometrically with standard cyclohexylamine solution. With certain specified sample compositions, approximate sulfuric acid determinations may be made without sample weighing or the use of standardized titrant. The titration is based upon the ratio of the first and second end points of the differential titration curve. Because of its simplicity, the latter method adaption is especially useful for routine control type analyses.

Determination of water content of granulated detergents

Abstract and SummaryA quick analytical procedure was described for the determination of water content of granulated detergents. A constant weight loss of sample was obtained within 5 min by microwave drying. The weight loss agrees with the water content by the modified distillation method. The coefficient of variation was 0.7%.

Determination of sodium sulfate in anionic surfactants by nonaqueous titration

A convenient and easy method was developed for nonaqueous titrimetric determination of sodium sulfate in the presence of sulfonate and sulfate type anionic surfactants. Sodium sulfate and the anionic surfactants were converted to sulfuric acid and the corresponding organo-sulfonic or organo-sulfuric acids by the addition of an excess of perchloric acid. The resulting acid mixture was then titrated in methanol with cyclohexylamine. The sulfate content was calculated from the difference of the two end points of the differentiating titration curve. For the determination of sodium sulfate in typical anionic surfactants, the relative standard deviation varied from 0.7 to 2.0% at the 0.3-10% sodium sulfate levels. The method provides a rapid and precise determination of inorganic sulfates in sulfonated or sulfated materials.