A method for analyzing a potential of a hydrocarbon reservoir, comprising: obtaining a rock sample (200, 1522, 1524, 1526) from the hydrocarbon reservoir; selecting a plurality of matrix standards (902, 1004, 1010, 1514, 1516) that have matrices that have a common characteristic with the rock sample (200, 1522, 1524, 1526); running a bulk isotope analysis on each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to determine a bulk isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); characterized in that the method further comprises: running a plurality of microprobe analyses on each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to determine a plurality of microprobe isotope ratio values for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); eliminating spurious values (1006, 1012) from the plurality of microprobe isotope ratio values; averaging the plurality of microprobe isotope ratio values for each of the plurality of matrix standards to create an average microprobe isotope ratio value (1002, 1008, 1014, 1518) associated with each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); plotting the bulk isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) against the average microprobe isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to create a matrix corrected calibration curve (1102, 1520); and running a microprobe analysis on a target region of the rock sample and using the matrix corrected calibration curve (1102, 1520) to determine an isotope ratio, δnM, for a selected element in the target region. obtaining a rock sample (200, 1522, 1524, 1526) from the hydrocarbon reservoir; selecting a plurality of matrix standards (902, 1004, 1010, 1514, 1516) that have matrices that have a common characteristic with the rock sample (200, 1522, 1524, 1526); running a bulk isotope analysis on each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to determine a bulk isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); characterized in that the method further comprises: running a plurality of microprobe analyses on each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to determine a plurality of microprobe isotope ratio values for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); eliminating spurious values (1006, 1012) from the plurality of microprobe isotope ratio values; averaging the plurality of microprobe isotope ratio values for each of the plurality of matrix standards to create an average microprobe isotope ratio value (1002, 1008, 1014, 1518) associated with each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); plotting the bulk isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) against the average microprobe isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to create a matrix corrected calibration curve (1102, 1520); and running a microprobe analysis on a target region of the rock sample and using the matrix corrected calibration curve (1102, 1520) to determine an isotope ratio, δnM, for a selected element in the target region. running a plurality of microprobe analyses on each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to determine a plurality of microprobe isotope ratio values for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); eliminating spurious values (1006, 1012) from the plurality of microprobe isotope ratio values; averaging the plurality of microprobe isotope ratio values for each of the plurality of matrix standards to create an average microprobe isotope ratio value (1002, 1008, 1014, 1518) associated with each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516); plotting the bulk isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) against the average microprobe isotope ratio value for each of the plurality of matrix standards (902, 1004, 1010, 1514, 1516) to create a matrix corrected calibration curve (1102, 1520); and running a microprobe analysis on a target region of the rock sample and using the matrix corrected calibration curve (1102, 1520) to determine an isotope ratio, δnM, for a selected element in the target region.