# US 2010/0167410 A1 · Mass-spectrometric method carried out on samples containing nucleic acids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2010/0167410 A1 - Document ID: US20100167410A1 - Status: Published application - Kind: A1 - Application number: 12/518,152 - Filed: 2007-12-07 - Published: 2010-07-01 - Earliest claimed: 2006-12-08 - Assignees: BioSpring Gesellschaft für Biotechnologie mbH; Johann Wolfgang Goethe-Universität Frankfurt am Main - Inventors: Huseyin Aygün; Michael Karas; Ute Bahr - Web page: https://patentgrep.com/patent/US20100167410A1 ## CPC - C12Q 1/68: involving nucleic acids - Y10T 436/143333: Saccharide [e.g., DNA, etc.] - Y10T 436/25125: Digestion or removing interfering materials - C12Q: MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS (immunoassay G01N33/53); COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract The invention relates to a mass spectrometric method for the detection and for the quantification of double stranded nucleic acids which are not covalently associated with one another. ## Claims ### Claim 1 A method for determining at least one property parameter of a sample which contains at least one nucleic acid, the property parameter being selected from the group consisting of double strand amount of the sample, ratio of single strands to double strands in the sample, and excess of a single strand with respect to a second single strand in the sample, the method comprising the steps of: (a) adding a standard to a sample containing at least one nucleic acid; (b) establishing a mass spectrum of the sample containing the standard under native conditions, said mass spectrum including at least one peak attributable to said at least one nucleic acid; (c) establishing a mass spectrum of the sample containing the standard under denaturing conditions, said mass spectrum including at least one peak attributable to said at least one nucleic acid; (d) comparing the peak height or peak area of the at least one peak attributable to the nucleic acid in the mass spectrum from step (b) with the peak height or peak area of the corresponding peak in the mass spectrum from step (c) to determine a property parameter of said sample. ### Claim 2 (depends on 1) The method according to claim 1, wherein said mass spectrum from steps (b) and (c) further comprise at least one peak attributable to said standard, further wherein the ratio of the peak signals corresponding to the standard in the mass spectra from steps (b) and/or (c) is considered with respect to one another. ### Claim 3 (depends on 1) The method according to claim 1, characterized in that the property parameter is the double strand amount of the sample. ### Claim 4 (depends on 1) The method according to claim 1, characterized in that the property parameter is the ratio of single strands to double strands in the sample. ### Claim 5 (depends on 1) The method according to claim 1, characterized in that the property parameter is the excess of a single strand with respect to a second single strand in the sample. ### Claim 6 (depends on 1) The method according to claim 1, characterized in that the denaturing conditions are produced by the addition of a denaturing agent, preferably by the addition of an acid. ### Claim 7 (depends on 1) The method according to claim 1, characterized in that the nucleic acid is DNA. ### Claim 8 (depends on 1) The method according to claim 1, characterized in that the nucleic acid is RNA. ### Claim 9 (depends on 1) The method according to claim 1, characterized in that the mass spectrometer is based on MALDI. ### Claim 10 (depends on 9) The method according to claim 9, characterized in that the MALDI sample matrix comprises a double strand stabilizing composition. ### Claim 11 (depends on 9) The method according to claim 9, characterized in that the MALDI sample matrix comprises 6-aza-2-thiothymine (ATT) and diammonium hydrogen citrate (DAHC). ### Claim 12 (depends on 1) The method according claim 1, characterized in that the standard is a single stranded nucleic acid. ### Claim 13 A method of preparing a sample which contains at least one nucleic acid for mass spectrometry, said method comprising the step of adding formic acid to said sample so as denaturize the at least one nucleic acid in the sample, wherein said formic acid is added in an amount such that it is available in a concentration of 10-30% by weight of the sample. ### Claim 14 A method of preparing a sample matrix for MALDI mass spectrometry, said method comprising the step of adding a mixture of 6-aza-2-thiothymine (ATT) and diammonium hydrogen citrate (DAHC) to the sample matrix for the MALDI mass spectrometry, wherein the DAHC used is in a concentration of 50-250 mM. ### Claim 15 (depends on 14) The method of preparing a sample matrix for MALDI mass spectrometry according to claim 14, characterized in that DAHC used is in a concentration of 100-200 mM. ### Claim 16 (depends on 14) The method of preparing a sample matrix for MALDI mass spectrometry according to claim 14, characterized in that said sample matrix comprises an optionally saturated solution of ATT is prepared in aqueous DAHC solution. ### Claim 17 (depends on 16) The method of preparing a sample matrix for MALDI mass spectrometry according to claim 16, characterized in that a sample is mixed with the sample matrix and the mixture is dried in an air current before mass spectrometry is carried out. ### Claim 18 (depends on 14) The method of preparing a sample matrix for MALDI mass spectrometry according to claim 14, characterized in that no organic solvents are used in the MALDI sample preparation.