A new fluorometric method is presented, based on data showing a linear relationship between CTC concentration and intensity of fluorescence of aluminum-CTC chelate, and little interference due to presence of decomposition products of CTC. A fairly good agreement was obtained between CTC values assayed by the microbiologic method and those by the proposed fluorometric method. Moreover, this method can be employed for field assay of CTC concentration in ice (Figs. 1,2, and Tables 1,3). A precise determination by using Beckman spectrophotometer : To a 10 cc aliquot of sample and each of standard solution series (1-5 mcg per cc) and 1 cc of a 1 % potassium alum (KA1(SO_4)_2?12H_2O) solution in M/2 acetate buffer of pH 4.6. Allow it to stand for 20 to 60 minutes at room temperature. Measure the fluorescence at a wave length of 500 mu of the sample when irradiated by an excitation light of 365 mu or 436 mu. Measure likewise the fluorescence of a series of standard solutions added with the alum reagent. Subtract the blank value from each measured intensity of fluorescence, and prepare a standard curve by plotting the intensity against the concentration of CTC. By employing this standard curve find the CTC concentration of the sample solution corresponding to its intensity of fluorescence which is corrected for the blank value. Approximate determination : The following methods are developed for the field work. (1) Test tube method : Place 10 cc of a supernatant of a thawed ice sample in a flat bottom test tube of equal diameter (about 27 mm), and add 1 cc of the alum reagent. After allowing it to stand for 5 to 10 minutes, observe the fluorescence from the top of the tubes irradiated with the black ray lamp from the side. Estimate CTC concentration of the ice sample by comparing the fluorescence of the sample with those of the standard series treated in the same way as the sample. (2) Portable nephelo-colorimeter method : Add a 1 cc aliquot of the alum reagent to both a 10 cc aliquot of supernatant of a thawed sample and a standard solution (4 or 2 mcg/cc depending on CTC content of sample). After allowing them to stand for 10 minutes, place the sample in one of the comparison tube (A) and the standard in the other tube (B), set the bottom of the inner tube for the tube (B) at a depth of 30 mm and by evenly irradiating with the long wave ultra-violet lamp and matching the intensity for tube (A) against that for tube (B), find the reading, h, for tube (A) where the intensity of the sample is identical with that of the standard. The content of CTC (mcg/cc) can be calculated by a formula, S×30/h, where S is the CTC concentration of the standard solution employed.サリチル酸およびサリチル酸アミドのような螢光性有機物はアルカリ,アルカリ土類および稀土類などの金属と酷塩をつくつて,発螢光性が強くなる.一方CTCはMgCl_2およびCaCl_2の溶液中で黄色の螢光を発し,またCa, Mgのような金属とキレート化合物をつくることが知られている.因つて著者はCTCのある種の金属キレート化合物は強い螢光を発するのではないかと想像し,分光光度計を用いてまず種々の金属イオンによる螢光度の差異をみたところ,アルミニウムイオンの存在によつてCTCの螢光が最も強くなることを見出したので,定量法の決定に必要な種々の条件を検討し一新定量法を決定することができた
