Vol. 4 8, No. 4
April, 1999
Kuniko Mitamura and Kazutake Shimada*
*Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1, Takara-machi, Kanazawa 920-0934
(Received 21 August 1998)An overview of high-performance liquid chromatography/mass spectrometry (LC/MS) of steroids is presented according to groups of steroids. LC/MS is now considered to be the most promising analytical method for the determination of steroids (especially the conjugated type) in biological fluids without derivatization. However, due to its low sensitivity compared with gas chromatography/MS, some skilful techniques, including derivatization, are necessary to overcome this problem. An overview of the ionization methods of LC/MS is also presented.
Keywords: high-performance liquid chromatography/mass spectrometry; ionization; steroid; conjugate; derivatization.
Kunihiro Watanabe, Manami Sakiyama, Fumio Nakadai and Masayuki Itagaki*
*Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, 2641, Noda-shi, Chiba 278-8510
(Received 6 October 1998, Accepted 5 December 1998)Hydroxy naphthol blue (HNB) has been a well-known reagent for Mn(II) catalitic analysis, and decomposes with only Mn(II) in the presence of hydrogen peroxide. When tiron is used as an activator, HNB is available for the determination of a trace amount of cobalt(II). By investigating the determination conditions for cobalt(II), it was found that the reaction rate of HNB decomposition decreased with increasing temperature above 25°C. The interesting effect of the temperature on the decomposition reaction was investigated by spectrometry. Azo dyes, like HNB, were decomposed by the hydroxy radical obtained with cobalt(II) and hydrogen peroxide. The behavior of tiron as an activator was to suppress the formation of the Co:HNB=1:2 complex, which acts as an inert intermediate relating to hydroxy radical formation. The active intermediate was estimated to be a Co(II):HNB=1:1 complex containing the tiron. High temperature accelerated the formation of a 1:2 complex. As a result, the rate of the decomposition reaction decreased above 25°C. The formation of an inert Co complex explained the decrease in the reaction rate under a high concentration of HNB. The complex ratio was determined by the molar-ratio method. The shape of the spectrum on the Co:HNB=1:2 complex was different from those of the Mn and Cu complexes. A calculation using ZINDO showed the structure of Co:HNB=1:2 complex. HNB's has connected with cobalt(II) at a large twisted angle, respectively.
Keywords : hydroxy naphthol blue; cobalt complex; effect of temperature; tiron; catalytic analysis.Naoki Yamaguchi, Yukiko Okada, Shogo Suzuki, Shoji Hirai* and Toshiaki Mitsugashira**
*Faculty of Engineering, Musashi Institute of Technology, 971, Ohzenji, Aso-ku, Kawasaki-shi, Kanagawa 215-0013
**The Oarai branch, Institute for Materials Research, Tohoku University, Narita-cyo, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1313
A new radiochemical procedure was developed for the isolation of activated molybdenum in high-purity iron irradiated by thermal neutrons. After irradiation, the sample was first dissolved in hydrochloric acid, and then (NH4)3PO4·12MoO3·3H2O(PMA) powder was added into the solution. To remove a major amount of the iron, ferric hydroxide were precipitated by the addition of NH4OH, while activated molybdenum remained in the alkaline solution as PMA. In order to attain high decontamination of up to 105 of iron from PMA, a trace amount of the remaining iron was removed by cation-exchange chromatography, and PMA was precipitated by adding excess hydrochloric acid. Finally, the precipitates were mounted for a sample for gamma-ray spectrometry. The overall recovery of activated molybdenum was 84%. The procedure was successfully applied to the determination of a ppb amount of molybdenum in high-purity iron.
Keywords : radiochemical neutron activation analysis; ppb amount of molybdenum in high-purity iron; (NH4)3PO4·12MoO3·3H2O; cation-exchange chromatography.
Yuuzi Shimizu and Takashi Saito*
*Department of Applied Chemistry, Kanagawa Institute of Technology, 1030, Shimoogino, Atsugi-shi, Kanagawa 243-0292
(Received 16 October 1998, Accepted 14 December 1998)The detection of a copper ion by an optical fiber sensing system using a polyvinyl chloride (PVC) membrane containing N,N'-bissalicyliden-2,3-diaminobenzofuran (SABF) as a detection port is discussed. A PVC membrane containing SABF and dioctylphthalate (DOP) was prepared and attached to the sensor port of an optical fiber sensor. A copper ion sample solution was added a 5×10-2 mol dm-3 counter ion solutions and a pH 6 buffer solution. Then, a sensor fixed in order PVC membrane was soaked in the sample solution. The absorbance of the colored membrane was measured by a spectrophotometer at 530 nm. The detectable concentration of the copper ion determined by the proposed method was over the range of 10-6~10-3 mol dm-3, and the reproducibility of the determined values of the copper ion was 2.0% as a relative standard deviation on repeatable experiments (six times) for 10-4 mol dm-3 of the copper ion sample. A linear correlation between the determined values by the proposed method and those by AAS was obtained over a concentration range of 1×10-5~1×10-4 mol dm-3. Coexisting metal ions had almost no effect on the determined values of copper ion. However, when zinc, nickel and magnesium ions coexisted with copper ions, it brought about negative interference to the determined values of copper ion.
Keywords: determination of copper ion; chelating reagent; optical fiber sensing; polyvinyl chloride membrane; solid phase extraction; spectrophotometry using membrane.
Yuzo Tamari*
*Konan University, 8-9-1, Okamoto, Higashinada-ku, Kobe-shi, Hyogo 658-0072
(Received 21 October 1998, Accepted 25 December 1998)The lithium content of infant formulas available in Japan was determined by flame photometry using an atomic-absorption spectrophotometer with an air-acetylene flame. Formula samples were decomposed by heating with a nitric-perchloric acid mixture, concentrated until almost dryness, and then diluted with a 0.1 mol/l hydrochloric acid solution. It was confirmed by a standard addition method that lithium was little interfered under high concentrations of the sodium and potassium contained in formulas. This method was applied to 16 Japanese infant formula samples, and the lithium content was determined: 106±13 (p<0.05) ng/g in 3 formulas for newborns; 178±42 (p<0.05) ng/g in 4 formulas for weaning infants; 118±10 (p<0.05) ng/g in 7 formulas for special use such as allergy, diarrhea and premature infants; 147±40 (p<0.05) ng/g in 7 milk-based formulas; and 123 ng/g in 2 soy-based formulas. The origin of lithium in the formulas may have been impurities of inorganic chemicals added as nutrition in manufacturing, based on correlation results between lithium and other chemical compositions of infant formulas (r=0.94 for Li/Ca, r=0.89 for Li/Mg, r=0.85 for Li/Na, r=0.90 for Li/K, r=0.86 for Li/P and r=0.94 for Li/Cl). As a conclusion, the daily dietary lithium intake has been estimated to be 12 µg for young infants fed on formulas and 20 µg for infants fed on weaning formulas.
Keywords: infant formula; lithium content; flame photometry; lithium origin; infant lithium intake.
Toshihiro Suzuki, Akiharu Hioki and Masayasu Kurahashi*
*National Institute of Materials and Chemical Research, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8565
(Received 9 December 1998, Accepted 4 January 1999)The photometric back-titration of barium with o-cresolphthalein complexone (PC), methylthymol blue (MTB), thymolphthalein complexone (TPC) or eriochrome black T (BT) as an indicator and EDTA as a chelate reagent was studied. The intersection of both the tangent at an inflection point and φ (apparent indicator transition)=1 was adopted as an end point of titration. The back-titration of barium with magnesium as a titrant and PC as an indicator showed the most sharp titration curve. Ammonium salt as a buffer did not interfere with the color transitions of PC and TPC until 0.5 mol dm-3. The color transition and end point of titration were, however, influenced by a large amount of neutral salt. The relative standard deviations of titration with PC were 0.034% (n=15) and 0.028%(n=10) for the barium and magnesium titrants, respectively. These two titration systems are recommended for barium titration. In spite that the titration with the barium titrant was less sharp than that with the magnesium titrant, the relative standard deviation of the former was close to that of the latter. This fact resulted because the shape of the titration curve with the barium titrant was advantageous for the precision of determining an end point.
Keywords: EDTA chelatometric titration; precision of determining an end point; barium; o-cresolphthalein complexone; methylthymol blue; thymolphthalein complexone.
Norio Manabe, Tsuyoshi Toyoda and Yoshimitsu Yokota*
*Suzuka Research Laboratory, Sumitomo Wiring Systems Co., Ltd., 1820, Nakanoike, Mikkaichi, Suzuka-shi, Mie 513-0803
(Received 14 October 1998, Accepted 6 January 1999)Pyrolysis-GC/MS in the presence of tetramethyl ammonium hydroxide (TMAH) was applied to the determination of one of the popular hindered phenol-type antioxidants, Irganox1010. The Irganox1010 contents for several polyethylene (PE) and poly(butylene terephthalate)[PBT] standard samples, prepaired by adding 0.05 to 0.5 wt% of Irganox1010, were determined on the basis of the peak intensity of the methylated compound formed during pyrolysis in the presence of TMAH at 250°C. The relative standard deviations(RSD) of this method were within 7% with a pretreatment to add not only TMAH, but also lauric acid and acetone for PE samples, and within 3% to add TMAH alone for PBT samples. This PyGC technique in the presence of TMAH can be used to determine the Irganox1010 content precisely and rapidly enough to be applied to determine the other phenol antioxidants and evaluation of the degradation process of polymer materials.
Keywords: pyrolysis-GC/MS; tetramethyl ammonium hydroxide; Irganox1010; anti-oxidant; polyethylene; poly(butylene terephthalate); degradation.
Kazuaki Wagatsuma*
*Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577
(Received 23 October 1998, Accepted 5 January 1999)Two major factors for selecting analytical lines, the sensitivity and the self-absorption effect, were compared between atomic lines and singly-ionized lines of copper as well as vanadium in glow discharge optical emission spectrometry. They have intense ionic lines which are excited through resonance charge-transfer collisions. It was found that the ionic lines are more sensitive compared to the atomic resonance lines; in addition, the ionic lines are essentially free from self-absorption, while the atomic lines suffer from self-absorption to a certain extent. The Cu II 224.70 nm, V II 309.31 nm, and V II 266.32 nm lines in the argon plasma, and the Cu II 270.32 nm line in the neon plasma are recommended as analytical lines of these elements.
Keywords: optical emission spectrometry; glow discharge plasma; analytical line; emission intensity; self-absorption; vanadium; copper.
Youichi Ishibashi
Analytical Center, Kohkankeisoku Corporation, 1-1, Minamiwatarida, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-0855
(Awarded by Hiroshima University dated February 12, 1998)This paper describes the development of on-site and on-line analyses and their applications to steel analysis. The problems accompanying laser ablation (LA) for different steel samples were resolved by adjusting the laser radiation conditions. The cw-Q-switched YAG laser was the best application system for steel analysis. The LA-ICP-AES was very useful for rapid and direct steel analysis in the process of steel-production control. The LA-ICP-MS resulted in a precision (RSD, %) ranging from 5% to 10% for most of the elements determined in steels. The on-line determination by the atomic-absorption spectrometric method was investigated to indirect monitoring of Mn in molten steel. The amount of Mn in the fine dust (<10 µm) reflected the Mn content in molten steel. The mass ratio of Mn to Fe depended on the evaporation temperature. The Mn content in the molten steel could be estimated from the Mn and Fe evaporation masses under a constant evaporation temperature. The evaporated dust generated from the converter was sent through a cyclone and buffers to reject particles with diameters larger than 10 µm, and only fine particles were directly introduced into the flame atomizer. There was a good correlation between the Mn content of the molten steel and that in the fine dust.
(Received November 20, 1998)Keywords: laser ablation; ICP-AES; ICP-MS; on-site analysis; on-line analysis; molten steel; manganese; atomic absorption analysis.
Kiyo Yamamoto
University of Shizuoka, 52-1, Yada, Shizuoka
(Awarded by University of Shizuoka, dated January 21, 1998)A method is used in which the melting-point depression is determined by differential scanning calorimetry (DSC) and the purity of an organic compound is subsequently determined. This method has an excellent feature not found in other methods: it is not possible to determine the content of individual impurities, but is possible to accurately determine the content of the total amount of impurities, including the content of unknown impurities. However, this method can only be used to accurately determine the purity of substances that are present in quantities of approximately 98 mol% or more. A study of measurement and data-proceeding analysis methods by DSC has been conducted in order to expand the application range of this method, with which determinations are quickly obtained, and to find more partial methods that can provide results with good precision and accuracy. As the result of this study, a determination by the DSC method yields values with an error of ±0.5 mol% for samples with a purity of 90 mol%. The technic described here improves purity determinations of organic compounds through the use of DSC.
(Received 19 December 1998)Keywords: purity determination; differential scanning calorimetry; container mold; heat of solution; van't Hoff equation; eutectic mixture.
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