Abstract: Embodiments are directed to systems and methods for using a contact signal to identify and account for parasitic leakage during operation of an electronic device. A test signal is applied to a set of electrodes to generate a contact signal that may be measured by processing circuitry of the device. The presence of extraneous materials between an electrode and a conductive, circuit-connected housing of the electronic device may reduce the amplitude of the contact signal. The device may perform a biological signal measurement based on whether the contact signal level is above a first threshold, thereby indicating an acceptable level of parasitic leakage. The device may also compare the contact signal level to a second threshold that indicates sufficient contact between the user and the electrodes. If the contact signal level is above the first threshold and below the second threshold, the device may perform a biological measurement.

Abstract: A method and system is provided for mass spectrometry for identification of a specific elemental formula for an unknown compound which includes but is not limited to a metabolite. The method includes calculating a natural abundance probability (NAP) of a given isotopologue for isotopes of non-labelling elements of an unknown compound. Molecular fragments for a subset of isotopes identified using the NAP are created and sorted into a requisite cache data structure to be subsequently searched. Peaks from raw spectrum data from mass spectrometry for an unknown compound. Sample-specific peaks of the unknown compound from various spectral artifacts in ultra-high resolution Fourier transform mass spectra are separated. A set of possible isotope-resolved molecular formula (IMF) are created by iteratively searching the molecular fragment caches and combining with additional isotopes and then statistically filtering the results based on NAP and mass-to-charge (m/2) matching probabilities.

Abstract: A method and system is provided for mass spectrometry for identification of a specific elemental formula for an unknown compound which includes but is not limited to a metabolite. The method includes calculating a natural abundance probability (NAP) of a given isotopologue for isotopes of non-labelling elements of an unknown compound. Molecular fragments for a subset of isotopes identified using the NAP are created and sorted into a requisite cache data structure to be subsequently searched. Peaks from raw spectrum data from mass spectrometry for an unknown compound. Sample-specific peaks of the unknown compound from various spectral artifacts in ultra-high resolution Fourier transform mass spectra are separated. A set of possible isotope-resolved molecular formula (IMF) are created by iteratively searching the molecular fragment caches and combining with additional isotopes and then statistically filtering the results based on NAP and mass-to-charge (m/2) matching probabilities.