The invention relates to a complex comprising an antibiotic substance and a nucleophilic derivatization reagent, compositions comprising the complex, kits comprising complex or composition, as well as uses of the complex or composition.

A method of gain calibration for an ion detector operating at a detector voltage is described. The method includes steps of: generating single ions; determining a parameter of a first relationship between a detector output of an ion detector and a number of ions for a first detector voltage; detecting an ion peak at the ion detector using the first detector voltage; adjusting the detector voltage; and determining a parameter of a second relationship between the detector output and the number of ions for the second detector voltage. A system including a mass spectrometer arrangement and a controller configured to operate the mass spectrometer arrangement in accordance with this method is also described.

An isotope ratio spectrometer is operated for measurement of a sample. First isotope ratios and first signal intensities are measured for a reference in the spectrometer, over a first measurement time period. A first relationship comprising a relationship between the first isotope ratios and the first signal intensities is determined. Sample isotope ratios and sample signal intensities are measured in the spectrometer, over a second measurement time period subsequent to the first measurement time period. Second isotope ratios and second signal intensities for a reference are measured in the spectrometer, over a third measurement time period subsequent to the second measurement time period. A second relationship comprising a relationship between the second isotope ratios and the second signal intensities is determined. A reference isotope ratio is estimated for a time X within the second measurement time period, based on the first relationship and the second relationship.

Before each sample of a series of batch samples is introduced into a liquid sample delivery device, an ion source device receives aqueous mobile phase solution from the liquid sample delivery device and ionizes its compounds, producing an ion beam. A tandem mass spectrometer performs a neutral loss or precursor ion scan on the ion beam to measure intensities of two or more precursor ions corresponding to a known aqueous mobile phase solution compound. Intensity measurements for each of the two or more different precursor ions are compared to previously stored intensities to determine the threshold times at which these measurements indicate orifice contamination. A threshold time is then predicted for a known compound of interest of the batch samples based on the m/z value of the known compound of interest and the m/z value and the threshold time of each of the two or more different precursor ions.

A method for correcting mass spectral m/z values comprises: detecting mass spectra for different amounts of sample ions within an ion trapping mass analyzer; evaluating an observable difference of relative m/z shift from the detected mass spectra of at least two of the different amounts of ions induced by space charge; evaluating a visible total charge Q.sub.v and/or the difference of a visible total charge Q.sub.v from the detected mass spectra; determining, from the evaluated observable differences of relative m/z shift and the evaluated visible total charges Q.sub.v and/or differences of the visible total charge Q.sub.v, a slope of a linear correlation between relative m/z shift and visible total charge Q.sub.v; determining a relative m/z shift of sample ions detected in a mass spectrum by multiplying visible total charge Q.sub.v with the determined slope; and correcting the m/z values in the mass spectrum using its determined relative m/z shift.

A mass spectrometer comprises an interface for receiving an ion beam from an ion source, a mass analyzer unit for selecting from the received ion beam, in two or more time periods, ions having different ranges of mass-to-charge ratios, a first detection unit for detecting, in each of said time period, ions within a selected range and producing first detection signals representative of quantities of detected ions having respective mass-to-charge ratios, and a second detection unit arranged between the interface and the mass analyzer unit for producing a second detection signal representative of a total intensity of the ion beam received from the ion source as a function of time. The mass spectrometer further comprises a processing unit for normalizing the first detection signals by using the second detection signal, which processing unit may output a ratio of normalized first detection signals.

According to an example aspect of the present invention, there is provided a method for preparing a gaseous isotope reference, the method comprising: providing a solid or liquid carbon-containing material exhibiting a carbon isotope ratio; providing oxygen gas or a gas mixture comprising oxygen gas, wherein said gas or gas mixture exhibits an oxygen isotope ratio; determining said carbon isotope ratio in the solid carbon-containing material and/or determining said oxygen isotope ratio in the oxygen gas or the gas mixture comprising oxygen; bringing the solid carbon-containing material in contact with the oxygen gas or the gas mixture comprising oxygen gas, in a high temperature in order to oxidize at least a part of the solid carbon-containing material to carbon dioxide to obtain the gaseous carbon and/or oxygen isotope reference in the form of carbon dioxide.

The present invention comprises novel methods of continuously monitoring the performance of an atmospheric pressure ionization (API) system. The methods of the invention allow for improved quality monitoring of the processes that leads to the formation of ions at atmospheric pressure. The methods of the invention further allow for continuously monitoring for the quality of the ion formation process in API without the addition of extraneous material (such as labelled compounds or control known compounds) to the system being monitored.

A computer implemented method for calibrating a customer mass spectrometry instrument (118) for quantifier-qualifier-ratio check is proposed. The method comprises the following steps: a) at least one manufacturer-site standardization, wherein a set of samples of a subject and a set of calibrator samples are measured in multiple replicates on a plurality of mass spectrometry instruments (114), wherein each measurement comprises multiple reaction monitoring with quantifier and qualifier transition for analyte and internal standard, wherein at least three adjustment factors are determined from the measurements of the set of samples of a subject and the set of calibrator samples, wherein a first adjustment factor α depends on a difference between analyte and internal standard, wherein a second adjustment factor β depends on a difference between samples of a subject and calibrator samples for analyte quantifier-qualifier-ratio, wherein a third adjustment factor γ depends on a difference between samples of a subject and calibrator samples for the internal standard quantifier-qualifier-ratio; b) at least one transfer step, wherein the adjustment factors are electronically transferred to a customer mass spectrometry instrument (118); c) at least one customer-site calibration, wherein the customer-site calibration comprises at least one calibration measurement, wherein a set of calibrator samples is measured on the customer mass spectrometry instrument (118) and quantifier-qualifier-ratios are determined therefrom, wherein target values for quantifier-qualifier-ratios for analyte and for internal standard are set by applying the adjustment factors on the determined quantifier-qualifier-ratios.

A method for correcting mass spectral data obtained for a sample is described, where the mass spectral data is a time-of-flight mass spectral data. The method includes receiving mass spectral data obtained from a sample, the mass spectral data being indicative of an ion abundance. The method further includes applying a correction function to the mass spectral data based on the ion abundance indicated by the mass spectral data and on one or more trapping parameters associated with the mass spectral data. The correction function defines correction values for the mass spectral data for a range of ion abundances and for a range of trapping parameters.