Abstract: A carbon isotope analyzer 1 includes a carbon dioxide isotope generator 40 that includes a combustion unit that generates gas containing carbon dioxide isotope from carbon isotope, and a carbon dioxide isotope purifying unit; a spectrometer 10 including an optical resonator 11 having a pair of mirrors 12, and a photodetector 15 that determines the intensity of light transmitted from the optical resonator 11; and a light generator 20 including a light source 23, a first optical fiber 21 to transmit a light beam from the light source 23, a second optical fiber 22 for wavelength conversion, the second optical fiber 22 splitting from the first optical fiber 21 at a point and combining with the first optical fiber 21 at another point downstream of the splitting point, and a non-linear optical crystal 25 that generates light having the absorption wavelength of the carbon dioxide isotope on the basis of the difference in frequency between light beams transmitted through the optical crystal 25.

Abstract: A carbon isotope analyzer 1 includes a carbon dioxide isotope generator 40 that includes a combustion unit that generates gas containing carbon dioxide isotope from carbon isotope, and a carbon dioxide isotope purifying unit; a spectrometer 10 including an optical resonator 11 having a pair of mirrors 12, and a photodetector 15 that determines the intensity of light transmitted from the optical resonator 11; and a light generator 20 including a light source 23, a first optical fiber 21 to transmit a light beam from the light source 23, a second optical fiber 22 for wavelength conversion, the second optical fiber 22 splitting from the first optical fiber 21 at a point and combining with the first optical fiber 21 at another point downstream of the splitting point, and a non-linear optical crystal 25 that generates light having the absorption wavelength of the carbon dioxide isotope on the basis of the difference in frequency between light beams transmitted through the optical crystal 25.

Abstract: A method in which an aqueous water-soluble compound solution containing at least one impurity in a slight amount is passed through a column packed with an adsorbent onto which the impurity is selectively adsorbed to thereby remove the impurity from the aqueous solution, wherein an abnormal phenomenon in adsorption chromatography is caused to obtain an elute fraction having a higher concentration of the trace impurity than the raw solution and this fraction is removed. Thus, the trace impurity can be efficiently removed and the water-soluble compound can be obtained in a high-purity state. Applying this method to aqueous sodium chloride solutions gives sodium chloride crystals reduced in impurity concentration. Dissolving such sodium chloride crystals, which have a low potassium ion concentration, in water provides an aqueous sodium chloride solution for medical use.