An atomic absorption spectrophotometric method for the direct determination of zinc in biological fluids has been developed, which does not require destruction or removal of organic material by ashing or precipitation prior to analysis. The sample is simply diluted with metal-free buffer or distilled water, and is then aspirated directly into the hydrogen-air flame of the atomic absorption device.
In this paper we are going to report the photodynamic action of cercosporin, a deep red pigment which was first isolated in 1957 by Kuyama and Tamura1) from the cultured mycelia of Cercospora kikuchii (Matsumoto et Tomoyasu) Gardner, a pathogenic fungus of purple speck of japanese soybean. The chemi cal structure of the formula of 1 was elucidated independently by Lousberg et al.2) and Yama
The laser-induced thermal lensing effect was applied to molybdenum blue colorimetry of phosphorus measurement. An Ar+ laser pumped rhodarnlne 101 laser was used as the heat and probe source. The signal from a silicon photocell with a 1 mm2 photosensitive surface, which was used as a laser radiation detector, was processed with an Inexpensive personal computer. The detection limit is 5 pg of P/mL which is determined mainly due to the deviation In the color development with the molybdenum blue method. The present method was applied to determine phosphorus in seawater and lake water.Methods for detecting trace phosphorus (nanogram level) in environmental samples Eire very limited. For exEimple, the spectroscopic technique did not reach the detection limit of 1 ng of phosphorus/mL in spite of many investigations using chemiluminescence, ICP, DCP, or AAS. Even nowadays, the most sensitive method is the classic molybdenum blue colorimetry based on the reduction of molybdenum in phosphor-molybdate. In combination with solvent extraction, determination of phosphorus at sub-part-per-billion levels is possible. However, even with this method, the concentration of phosphorus in some natural waters cannot be measured. In the environmental water system, the concentration of phosphoric acid necessary to induce eutrophication is sometimes less than a detectable amount. Among the various attempts to improve molybdenum blue colorimetry, the present study applied thermal lensing colorimetry using Ar+ laser pumped dye laser.LEiser-induced thermal lensing effect was first investigated by Gordon et al. (1), and it is pointed out that thermal lensing colorimetry is an important way to monitor small absorbance. Recently, Dovichi and Harris studied the theoretical aspects of various applications of thermal lensing colorimetry to analytical chemistry (2-4). Imasaka and Ishibashi reported the detection of iron by the thermal lensing effect (5, 6).Haushalter and Morris (7) applied thermal lensing colorimetry to monitor enzymatic reaction involving dopamine which could not be sensitively detected by other spectrometric methods, including fluorometry. Because of its high sensitivity, the feasibility for laser-induced thermal lensing colorimetry in environmetal analysis cannot be ignored. In a previous paper (8), we reported on thermEd lensing colorimetry of nitrite ions wherein color development was based on the diazo-coupling reaction. The detection limit of nitrite ions was thus improved about 500 times over ordinary colorimetry. In the present paper, determination of parts per trillion levels of phosphorus by the thermal lensing effect is discussed, along with signal processing by a personal computer. This method was applied to the analysis of phosphorus in seawater and lake water.
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