KBH4 Concentration Research Articles

Atomization of Hydride with a Low-Temperature, Atmospheric Pressure Dielectric Barrier Discharge and Its Application to Arsenic Speciation with Atomic Absorption Spectrometry

This paper describes a novel hydride atomizer based on atmospheric pressure dielectric barrier discharge (DBD) plasma. The plasma was generated with a 3700-V, 20.3-kHz, and 5-W electrical power supply and easily sustained with inert gases (He or Ar) at a flow rate of 250 mL.min(-1) after optimization. However, it cannot be sustained with N2. This atomizer offers the advantages of low operation temperature and low power consumption in comparison with the currently used electrothermal quartz atomization operated at 900 degrees C with a power supply of several hundred watts. To confirm the utility of the proposed atomizer, four arsenic species (As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA)) were determined by the present atomization technique. A hyphenation of HPLC coupled to hydride generation AAS with the optimized DBD atomizer has been successfully used for the speciation of arsenic in order to demonstrate the potential of this atomizer in the present study. The characteristics of the DBD atomizer and the effects of different parameters (discharge gas, gas flow rate, voltage, HCl concentration, KBH4 concentration) are discussed in the paper. Compared with other hydride atomization techniques, the proposed method shows the following features: (1) small size (70 mm x 15 mm x 5 mm), which is preferable for the miniaturization of the total analytical system; (2) low power consumption (< or =5 W), which indicates the possibility of the development of portable, fieldable analytical instrumentation for in situ detection using battery as power supply; (3) low atomizer temperature (approximately 70 degrees C), which is in favor of the compactness of the total instruments; (4) avoidance of residue moisture removal in comparison with the existed GD system, which leads to the facility of the system. The analytical figures of the present technique were evaluated. The detection limits of As(III), As(V), MMA, and DMA obtained with HG-DBD-AAS were 1.0, 11.8, 2.0, and 18.0 microg.L(-1), respectively. The accuracy of the system was verified by the determination of arsenic in reference material of orchard leaves SRM 1571. The concentration of As determined by the present method agreed well with the reference values. The speciation of arsenic in the freeze-dried urine SRM 2670 were carried out, and the results obtained were in agreement with the results of HPLC-ICPMS and the reported values by other laboratories.

接触めっき法によるＦｅ‐Ｂ二元系アモルファス合金薄膜の作製と磁気特性

Fe-B amorphous alloy film was formed by means of contact plating method, in which Cu foils in contact with Al wires were used as substrates. Local battery configuration of the Cu foil anode and the Al wire cathode was responsible for film formation. The boron content in film was controlled from 0at% to 28at% by changing the KBH4 concentration in the bath. The bath temperature strongly affected the crystallographic structure of resultant films. Fe80B20 amorphous films required a bath temperature below 40°C. Film structure and composition also affected magnetic properties. Film coercivity below 17Oe was also observed.

マイクロ磁気デバイスへの応用を目的としたＦｅ‐Ｂアモルファス電析膜の作製

Amorphous (a-) Fe-B alloy films for micro-magnetic device applications were fabricated by electrodeposition. It was found that an appropriate KBH4 concentration greater than 300mM and a bath temperature of less than 30°C were indispensable deposition conditions for obtaining a-Fe-B films with a B concentration exceeding 20at%. Furthermore, a-Fe-B films with low coercivity of less than 3.6 Oe and a large magnetostrictive constant of 26×10-6, which are thus comparable to sputtered a-Fe-B films, can be obtained by using a combined complex agent consisting of KNaC4H4O6 and (NH4)2SO4. ESCA measurements showed that about 80at% boron chemically bound with iron, but about 20at% boron combined with oxygen, because the electrodeposited films contain oxygen and carbon.