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US 9,754,774 B2Granted
Systems and methods for automated analysis of output in single particle inductively coupled plasma mass spectrometry and similar data sets
AssigneePerkinElmer Health Sciences, Inc.
InventorsSamad Bazargan, Hamid Badiei
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Abstract
The present disclosure provides methods and systems for automated analysis of spectrometry data corresponding to particles of a sample, such as large data sets obtained during single particle mode analysis of an inductively coupled plasma mass spectrometer (SP-ICP-MS). Techniques are presented herein that provide appropriate smoothing for rapid data processing without an accompanying reduction (or with an acceptably negligible reduction) in accuracy and/or precision.
Claims18
A method for automated analysis of spectrometry data corresponding to particles of a sample, the method comprising:
- (a) detecting, by a detector of an inductively coupled plasma mass spectrometer (ICP-MS), one or more ions, wherein the spectrometer acquires a sequence of pulse count values in response to the one or more ions striking the detector;
- (b) accessing, by a processor of a computing device, the sequence of pulse count values, wherein the sequence of pulse count values is acquired by the spectrometer at a rate fast enough to produce, for at least one given peak corresponding to an individual particle comprising an analyte in the sample, a plurality of pulse count values each of which is greater than a threshold background intensity value;
- (c) determining, by the processor, from a first array of the pulse count values, a threshold for identifying pulse count values as corresponding to a peak signal, and adjusting the threshold based on remaining pulse count values following each of a series of iterations, with a given subsequent iteration further excluding pulse count values identified as corresponding to a peak in the preceding iteration, wherein a final background threshold is determined upon convergence of the threshold within acceptable tolerance;
- (d) building, by the processor, from the first array of the pulse count values, a smoothed data array, identifying as peaks the values of the smoothed data array that are larger than both subsequent and preceding values and larger than the final background threshold;
- (e) identifying, by the processor, a peak area intensity corresponding to each of the identified peaks for the sample and constructing, by the processor, a histogram of peak area intensities for the sample;
- (f) computing, by the processor, using the histogram of peak area intensities for the sample, one or more of (i) to (ix) as follows:
- (i) a particle mass histogram for the sample, (ii) a particle size histogram for the sample, (iii) a number of peaks detected for the sample, (iv) a particle concentration for the sample, (v) a mean particle size for the sample, (vi) a median particle size for the sample, (vii) a dissolved analyte concentration for the sample, (viii) a mode particle size, and (ix) a measure of width of particle size distribution;
- and
- (g) rendering, by the processor, for presentation on a display, a graphical and/or alphanumeric representation of one or more of (i) to (xi) as follows:
- (i) the identified peaks for the sample, (ii) the histogram of peak area intensities for the sample, (iii) the particle mass histogram for the sample, (iv) the particle size histogram for the sample, (v) the number of peaks detected for the sample, (vi) the particle concentration for the sample, (vii) the mean particle size for the sample, (viii) the median particle size for the sample, (ix) the dissolved analyte concentration for the sample, (x) the mode particle size, and (xi) the measure of width of particle size distribution;
- wherein step (f) further comprises:
- determining, by the processor, an intensity versus mass calibration for the sample using:
- (I) a most-common intensity determined from an intensity histogram produced from an ICP-MS run of a standard particle having a known size and the same composition as the particles of the sample, (II) a determined or known shape of the standard particle, and (III) a determined or known density of the standard particle;
- and
- computing the particle mass histogram for the sample using:
- (I) the intensity versus mass calibration for the sample, (II) a mass fraction of the particle that is the analyte, and (III) an ionization efficiency.
13 more elements
A system for automated analysis of spectrometry data corresponding to particles of a sample, the system comprising:
- an inductively coupled plasma mass spectrometer (ICP-MS) comprising a detector, wherein the spectrometer acquires a sequence of pulse count values in response to one or more ions striking the detector;
- a processor;
- and
- a memory, wherein the memory comprises instructions that, when executed by the processor, cause the processor to:
- (a) access the sequence of pulse count values, wherein the sequence of pulse count values is acquired by the spectrometer at a rate fast enough to produce, for at least one given peak corresponding to an individual particle comprising an analyte in the sample, a plurality of pulse count values each of which is greater than a threshold background intensity value;
- (b) determine, from a first array of the pulse count values, a threshold for identifying pulse count values as corresponding to a peak signal, and adjust the threshold based on remaining pulse count values following each of a series of iterations, with a given subsequent iteration further excluding pulse count values identified as corresponding to a peak in the preceding iteration, wherein a final background threshold is determined upon convergence of the threshold within acceptable tolerance;
- (c) build, from the first array of the pulse count values, a smoothed data array, identifying as peaks the values of the smoothed data array that are larger than both subsequent and preceding values and larger than the final background threshold;
- (d) identify a peak area intensity corresponding to each of the identified peaks for the sample and construct a histogram of peak area intensities for the sample;
- (e) compute, using the histogram of peak area intensities for the sample, one or more of (i) to (ix) as follows:
- (i) a particle mass histogram for the sample, (ii) a particle size histogram for the sample, (iii) a number of peaks detected for the sample, (iv) a particle concentration for the sample, (v) a mean particle size for the sample, (vi) a median particle size for the sample, (vii) a dissolved analyte concentration for the sample, (viii) a mode particle size, and (ix) a measure of width of particle size distribution;
- and
- (f) render for presentation on a display, a graphical and/or alphanumeric representation of one or more of (i) to (xi) as follows:
- (i) the identified peaks for the sample, (ii) the histogram of peak area intensities for the sample, (iii) the particle mass histogram for the sample, (iv) the particle size histogram for the sample, (v) the number of peaks detected for the sample, (vi) the particle concentration for the sample, (vii) the mean particle size for the sample, (viii) the median particle size for the sample, (ix) the dissolved analyte concentration for the sample, (x) the mode particle size, and (xi) the measure of width of particle size distribution;
- wherein the instructions, when executed by the processor, cause the processor, at step (e), to:
- determine an intensity versus mass calibration for the sample using:
- (I) a most-common intensity determined from an intensity histogram produced from an ICP-MS run of a standard particle having a known size and the same composition as the particles of the sample, (II) a determined or known shape of the standard particle, and (III) a determined or known density of the standard particle;
- and
- compute the particle mass histogram for the sample using:
- (I) the intensity versus mass calibration for the sample, (II) a mass fraction of the particle that is the analyte, and (III) an ionization efficiency.
16 more elements
Dependencies are inferred from the claim text.