At Osaka University, a large two-stage double-focusing mass spectrometer was constructed and its focus-adjustment work is in progress at present. With the new machine, the authors are intending to determine the atomic masses to an accuracy of one part in10⁹or somewhat higher using the peak matching technique. To realize the measurements with such a high accuracy, one of the most important things is the setting up of a high precision voltage divider as the main part of the potential supplying system for the ion-energy selector of the machine. The construction work of this precise voltage divider was finished, and the preliminary resistance calibration of the resistors composing the divider was carried out. The divider consists of three groups; a variable resistance assemblyΔR, a main fixed resistance assembly R and an auxiliary one R'. These assembly, are connected in aπ-shape network as Nier's circuit. Each of the R and R' consists of one hundred 100-kΩresistors to form a total resistance of 10MΩ. All these100-kΩresistors are selected to match with each other to whithin one part in 10⁴. TheΔR consists of a100-kΩresistor and six decades of 10kΩ, 1kΩ, 100Ω, 10Ω, 1Ω, and 0.1Ωper step. The whole system is installed in a box temperature-controlled at30±0.1°C. In this resistance assembly, it is required to know only the ratio values ofΔR/R irrespective of the absolute values of the resistances. All the resistors were calibrated referring to an internal standard with an accuracy of one part per million or less, using the standard bridge technique. For the evaluation of R, the simple relation of the series to parallel resistance ratio was adopted.

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An attempt to detect metastable helium atoms from a plasma gun by means of detecting Auger electrons from a tungsten surface has been performed to investigate the mechanism in the interaction between a helium plasma and a helium gas target. A bunch of metastable helium atoms with a duration of about 100μsec was observed about150μsec after the firing of the plasma gun. This fact would support the previous result of spectroscopic measurements.

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A rapid and precise method of¹⁸ 0 analysis for milligram quantities of water by using a modified CO2-H2O equilibration technique at the temperature of 1210°Cand1410°Chas been developed. The reproducibility in¹⁸ 0 analyses is found to be±0.1‰which is compared favorably with the methods reported previously. There are no measurable errors due to the memory effect and oxygen isotope exchange between CO2-H2O mixture and instrument glass.An aliquot of a water sample equilibrated with CO2 for¹⁸ 0 analysis can be used subsequently for D analysis.

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The ion transmission efficiency in mass filters depends markedly on mass-to-charge ratio, and this dependence also varies with the resolving power. This paper describes a very simple method for measuring there rative transmission efficiency without introducing test gases to a system. The method is based on the property of mass filters that ions of different mass-to-charge ratio have the same transmission efficiency at the poorest resolving power. Examples of the results are given. The results are compared with those measured by in troducing test gases.

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In a previous paper, we reported the availability of mass spectrometry as a useful technique for the identification of drug metabolites. In this paper, the metabolites excreted in urine and bile following oral administration of 4-[2'-(2″, 3″-Dihydroxy propoxy carbonyl)phenylamino]7-chloroquinoline (I) in rats were investigated by a mass spectrometric technique as shown in Fig. 2. Of the six metabolites suspected to be present in urine and eight metabolites in bile, the structures of three metabolites were elucidated to be 4-[2'-(2″, 3″-Dihydroxy propoxy carbonyl) phenylamino]7-chloroquirioline (I), 4-[2'-(Carboxyl)phenylamino]7-chloroquinoline (II) and 4-[2'-(Carboxymethyl)phenylamino]7-chloroquinoline (IV) .

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The necessary conditions for the good quantitative analysis of mass spectra obtained for a mass spectrometer of the Mattauch-Herzog type are derived theoretically and confirmed experimentally. The operational condition of the mass spectrometer is most conveniently expressed by using the peak frequency νp which is defined as the reciprocal of the time duration elapsed by the passage of one peak. Normally νp is given by the following equation:νp=K/ [ (Sc+G?SM)M^1/2τ ], where Sc and SM are the widths of the collector and the main slit respectively, G the magnification of the image, M the molecular weight of the ion, τthe scan time and K a constant. The constant K can be determined experimentally for a given apparatus. The wellknown flat top conditions, which are necessary for the good quantitative mass spectrometry, can be related to this peak frequency νp. In the case of the mass spectrometer of the Mattauch-Herzog type used in the experiment, the flat top peak appears when2.5 SM≤ Sc andν≥2νp, whereνis the response frequency of the electrical recording system. Since the resolving power R of the mass spectrometer is determined by the slit widths, the relationship betweenνand Rf(the flat-top resolving power)can also be obtained from the above conditions. These treatments are useful especially for rapid magnetic scanning. An example of the conditions for the quantitative mass spectrometry obtained from the above theory is as follows;SM=15μm, Sc=40μm, Rf=2700, ν≥1.6kHz(by a visigraph recorder), τ5 sec(m/e 14 to 50). The experiments show that the accuracy of the quantitative analysis of gas components is tolerable under the above conditions, but the accuracy decreases very rapidly ifνor τdoes not satisfy these conditions.

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