Abstract: An atmospheric pressure ionization method uses: a gas flow passage control unit (26) and a gas outlet nozzle (24) configured to jet argon gas to an atmospheric atmosphere; a needle electrode (19) arranged between an outlet port of the gas outlet nozzle (24) and an introduction port of an ion introduction pipe (6) that includes a tip end portion formed into a two-sheeted hyperboloid of revolution having a radius of curvature of 1 ?m or more and less than 30 ?m; a needle electrode support mechanism (20); and an electric power generation unit (22) configured to apply a voltage to the needle electrode (19). The atmospheric pressure ionization method includes: applying a voltage of 1.8 kV or more to the needle electrode (19) from the voltage generation unit (22) to generate a dark discharge; exciting the argon gas with the dark current; and causing the excited argon gas and the sample to react with each other, to thereby ionize the sample.

Abstract: An atmospheric pressure ionization method uses: a gas flow passage control unit (26) and a gas outlet nozzle (24) configured to jet argon gas to an atmospheric atmosphere; a needle electrode (19) arranged between an outlet port of the gas outlet nozzle (24) and an introduction port of an ion introduction pipe (6) that includes a tip end portion formed into a curved surface; a needle electrode support mechanism (20); and an electric power generation unit (22) configured to apply extremely low electric power to the needle electrode (19). The atmospheric pressure ionization method includes: applying the extremely low electric power to the needle electrode (19) from the electric power generation unit (22) to generate a dark discharge; exciting the argon gas with the dark current; and causing the excited argon gas and the sample to react with each other, to thereby ionize the sample.

Abstract: In the ionizer of the present invention, a stream of gas spouted from a nozzle (18) of a DART ionization unit (10) vaporizes and ionizes the components in a sample (25). Gaseous sample-component molecules which have not been ionized by that process are subsequently ionized by a reaction with a reactant ion produced by a corona discharge generated from a needle electrode (20). Such a two-stage ionization of the sample-component molecules improves the ionization efficiency. A needle-electrode support mechanism (21) adjusts the position and/or angle of the needle electrode (20) and thereby controls a potential gradient. Therefore, a specific sample-derived ion species can be efficiently introduced into an ion introduction tube (31) and be detected with a high level of sensitivity.

Abstract: In the ionizer of the present invention, a stream of gas spouted from a nozzle (18) of a DART ionization unit (10) vaporizes and ionizes the components in a sample (25). Gaseous sample-component molecules which have not been ionized by that process are subsequently ionized by a reaction with a reactant ion produced by a corona discharge generated from a needle electrode (20). Such a two-stage ionization of the sample-component molecules improves the ionization efficiency. A needle-electrode support mechanism (21) adjusts the position and/or angle of the needle electrode (20) and thereby controls a potential gradient. Therefore, a specific sample-derived ion species can be efficiently introduced into an ion introduction tube (31) and be detected with a high level of sensitivity.

Abstract: The present invention provides a peptide degradation reagent with the following characteristics: 1) it has no marked toxicity such as carcinogenicity, 2) it does not produce metastable peaks resulting from excessive degradation property, 3) it does not produce multiply-charged ion peaks which are interference peaks, and 4) it can secure separation and sharpness of peaks. The present invention also provides a method for specifically cleaving N—C? bonds on a peptide backbone using the above-described reagent, and a method of determining the amino acid sequence of a peptide utilizing this specific cleavage. A method for specifically cleaving N—C? bonds on the backbone of a peptide, comprising irradiating the peptide with laser light in the presence of 5-amino salicylic acid. A method for determining the amino acid sequence of a peptide, comprising irradiating the peptide with laser light in the presence of 5-amino salicylic acid to thereby specifically cleave N—C? bonds on the peptide backbone.