Methods are described for measuring the amount of C peptide in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying C peptide in a sample utilizing on-line extraction methods coupled with tandem mass spectrometric or high resolution/high accuracy mass spectrometric techniques.

In an inductively coupled plasma-mass spectrometry (ICP-MS) system, ions are transmitted into a collision/reaction cell. A DC potential is applied at an exit of the cell at a first magnitude to generate a DC potential barrier effective to prevent the ions from exiting the cell. The DC potential barrier is maintained during a confinement period to perform an interaction. After the confinement period, analyte ions or product ions are transmitted to a mass spectrometer by switching the exit DC potential to a second magnitude effective to allow the analyte ions or product ions to pass through the cell exit as a pulse. The analyte ions or product ions are then counted during a measurement period. The interaction may be ion-molecule reactions or ion-molecule collisions.

Certain configurations described herein are directed to mass spectrometer systems that can use a gas mixture to select and/or detect ions. In some instances, the gas mixture can be used in both a collision mode and in a reaction mode to provide improved detection limits using the same gas mixture.

A mass spectrometry method comprises: generating ions; directing the ions through an ion optical component within a first chamber having a first vacuum pressure, the ion optical component maintained at a first electrical potential; transferring the ions through an ion guide within a second chamber having a second vacuum pressure less than the first vacuum pressure, the ion guide maintained at a second electrical potential, wherein a difference between the first and second potentials imparts kinetic energy that causes collision-induced ion fragmentation within the second chamber that removes adduct species; and transferring the ions into another ion guide within a third chamber having a third vacuum pressure less than the second vacuum pressure, the other ion guide maintained at a third electrical potential, wherein a difference between the third and second potentials reduces a portion of the imparted kinetic energy of the ions passing into the third chamber.

A method of mass spectrometry is disclosed comprising: performing a plurality of cycles of operation during a single experimental run, wherein each cycle comprises: mass selectively transmitting precursor ions of a single mass, or range of masses, through or out of a mass separator or mass filter at any given time, wherein the mass separator or mass filter is operated such that the single mass or range of masses transmitted therefrom is varied with time; and mass analysing ions.

RF ion guides are configured as an array of elongate electrodes arranged symmetrically about a central axis, to which RF voltages are applied. The RF electrodes include at least a portion of their length that is semi-transparent to electric fields. Auxiliary electrodes are then provided proximal to the RF electrodes distal to the ion guide axis, such that application of DC voltages to the auxiliary electrodes causes an auxiliary electric field to form between the auxiliary electrodes and the ion guide RF electrodes. A portion of this auxiliary electric field penetrates through the semi-transparent portions of the RF electrodes, such that the potentials within the ion guide are modified. The auxiliary electrode structures and voltages can be configured so that a potential gradient develops along the ion guide axis due to this field penetration, which provides an axial motive force for collision damped ions.

In a tandem mass spectrometer, when the measurement mode is switched between a positive ion measurement mode and a negative ion measurement mode, a DC offset voltage applied to a lens electrode to impart collision energy to an ion is temporarily switched to 0 V (S1). After being maintained at 0 V for a predetermined waiting time (S2), the voltage is changed to a DC offset voltage corresponding to a measurement mode which is used after the switching operation (S3). By such an operation, the voltage difference between the neighboring plate electrodes among the plate electrodes (171, 172, 173) included in the lens electrode can be decreased as compared to the case where the polarity of the DC offset voltage is immediately switched. Consequently, unintended electric discharge between the neighboring electrodes can be prevented.

Methods are described for measuring the amount of C peptide in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying C peptide in a sample utilizing on-line extraction methods coupled with tandem mass spectrometric or high resolution/high accuracy mass spectrometric techniques.

Certain aspects of the present disclosure are generally directed to monitoring different decoding candidates assuming different encoding schemes. For example, certain aspects of the present disclosure are directed to a method for wireless communication. The method generally includes determining a first encoding scheme used to encode first downlink control information (DCI) and a second encoding scheme used to encode second DCI, and monitoring one or more first decoding candidates for the first DCI based on the first encoding scheme and one or more second decoding candidate for the second DCI based on the second encoding scheme.

In a simultaneous multicomponent analysis for a number of target compounds, an MRM transition which does not give the highest signal intensity but gives a lower signal intensity is selected for a compound having a high measurement sensitivity or a compound having a high measurement target concentration. If the signal intensity is still high, the level of collision energy (CE) is changed from an optimum level. The MRM transition, CE level and other measurement conditions determined for each compound in this manner are stored in a compound-related information storage 41. In the process of preparing a control sequence for the simultaneous multicomponent analysis, the measurement conditions stored in the storage section 41 are used. The use of those conditions prevents the saturation of the signal for a high-concentration compound while ensuring a sufficiently high level of sensitivity for a low-concentration compound.