Masayuki Uto

Spectrophotometic Determination Of Tin In Steels With2-(5-Nltro-2-Pyridylazo)-5-[N-n-Propyl-N-(3-Sulfopropyl)Amino]phenol

ABSTRACT A highly sensitive azo dye, 2-(5-nitro-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]phenol (Nitro-PAPS), is used as a colorimetric reagent for the determination of tin(IV) content. Nitro-PAPS reacts with tin(IV) to form a water-soluble complex in 1.0 M acetic acid. Full color development is attained within 5 minutes, and maintains constant absorbance for at least 24 hours. The apparent molar absorptivity is 7.7 x 104 dm3 mol−1 cm−1 at a maximum wavelength of 580 ran. Beers law is obeyed for tin(IV) in the range of 0-1.2 μg ml−1. The proposed method is successfully applied to the determination of trace amounts of tin in steels.

Study of the Metal Coated Hollow Fiber Membrane Electrode for the Amperometric Sugar Detection and the Sensitivity.

The metal coated hollow fiber membrane (MCH) has been applied as a working electrode of an electrochemical detector for high performance liquid chromatography (HPLC). In this paper, the improvements of the sensitivity of the copper coated hollow fiber membrane (Cu-MCH) electrode as a sensor for carbohydrates were described. The MCH electrode had the tubular structure. Therefore, there was a problem of decreasing the output signal by dilution of analysis with the dependence on the inside volume. In order to reduce the inside volume, the plug put inside of the MCH and a thinner hollow fiber membrane were used. The plug was effective to make the MCH electrode sensitive resulting the detection limit (S/N=3) of glucose lowered from 1.7 pmol to 0.95 pmol. The hollow fiber membrane in which inside diameter was thinner was also effective. The detection limit dropped from 1.7 pmol to 0.56 pmol, when it was changed to 0.6 mm from 1.0 mm. In addition, it was effective to decrease the noise current when the hollow fiber membrane of 0.6 mm inside diameter was covered with the copper on the gold (Cu/Au-MCH).The detection limit was improved to 0.24 pmol. The simultaneous detection of sorbitol, glucose, fructose, lactose, saccharose, raffinose and maltose was demonstrated with the Cu/Au-MCH in HPLC. The detection limits were 0.39, 0.24, 0.39, 0.38, 0.58, 0.53 and 0.82 pmol, respectively.