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Light intensity data quantifying intensity of light generated by a light source and received at a detector during a validation mode of an absorption spectrometer can be compared with a stored data set representing at least one previous measurement in a validation mode of an analytical system. The va

Light intensity data quantifying intensity of light generated by a light source and received at a detector during a validation mode of an absorption spectrometer can be compared with a stored data set representing at least one previous measurement in a validation mode of an analytical system. The validation mode can include causing the light to pass at least once through each of a zero gas and a reference gas contained within a validation cell and including a known amount of a target analyte. The zero gas can have at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source. A validation failure can be determined to have occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount. Related systems, methods, and articles of manufacture are also described.

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1. An apparatus comprising: a validation cell positioned such that a light path generated by a light source passes through the validation cell at least once in transmission of the light path from the light source to a detector, the validation cell containing a reference gas comprising a known amount

1. An apparatus comprising: a validation cell positioned such that a light path generated by a light source passes through the validation cell at least once in transmission of the light path from the light source to a detector, the validation cell containing a reference gas comprising a known amount of a target analyte;a flow switching apparatus to direct a sample gas into the light path during a sample analysis mode and a zero gas into the light path during a validation mode, the zero gas having at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source; anda controller to perform operations comprising:receiving light intensity data quantifying intensity of the light received at the detector during the validation mode,comparing the light intensity data with a stored data set representing at least one previous measurement in the validation mode; anddetermining that a validation failure has occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount. 2. An apparatus as in claim 1, wherein: the light intensity data comprise first light intensity data quantifying the intensity of the light path received at the detector during a first phase of the validation mode in which the validation cell is maintained at a first temperature and second light intensity data of the light path received at the detector during a second phase of the validation mode in which the validation cell is maintained at a second temperature that differs from the first temperature, and the determining that the validation failure has occurred comprises identifying that a first line shape of the first light intensity data and a second line shape of the second light intensity data deviate from a stored data set by a first deviation amount that exceeds a pre-defined threshold amount, the stored data set comprising previously recorded line shapes at the first temperature and the second temperature, respectively. 3. An apparatus as in claim 1, wherein the operations performed by the controller further comprise: promoting an alert that the validation failure has occurred. 4. An apparatus as in claim 1, further comprising: a temperature control apparatus to maintain the validation cell at least at one of the first temperature and the second temperature. 5. An apparatus as in claim 1, further comprising a sample measurement cell to contain an analysis volume, the sample measurement cell being positioned such that the light path passes at least once through each of the analysis volume in the sample measurement cell and the reference gas in the validation cell during transmission of the light path from the light source to the detector. 6. An apparatus as in claim 5, further comprising: an optical cell that comprises the validation cell and the sample measurement cell. 7. An apparatus as in claim 1, wherein the operations performed by the controller further comprise: making a first modification to at least one of an operating parameter and an analytical parameter of at least one of the light source, the detector, and the controller in response to the determining that the validation failure has occurred;receiving new light intensity data of the light path received at the detector during a repeated validation mode occurring after the first modification of the at least one operating parameter;comparing the new light intensity data with the stored data set, anddetermining whether the new light intensity data and the stored data set are out of agreement by more than the predefined threshold amount and if so, whether the new light intensity data and the stored data set are in closer agreement than the light intensity data and the stored data set. 8. An apparatus as in claim 1, wherein the light source comprises a tunable or scannable laser of a laser absorption spectrometer, and the stored data set comprise a reference harmonic absorption curve of the laser absorption spectrometer, the reference harmonic absorption curve having a reference curve shape and comprising at least one of a first or higher order harmonic signal of a reference signal generated by the detector in response to the light path passing from the light source through the reference gas in the validation cell, the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;the light intensity data comprises a test harmonic absorption curve having a test curve shape; andthe predefined threshold amount comprises a predefined allowed deviation between the test curve shape and the reference curve shape. 9. An apparatus as in claim 8, wherein the operations performed by the controller further comprise: adjusting one or more operating and/or analytical parameters of the laser absorption spectrometer to correct the test curve shape to reduce the difference between the test curve shape and the reference curve shape. 10. An apparatus as in claim 9, wherein the one or more operating and/or analytical parameters of the laser absorption spectrometer comprise at least one of laser light source parameters, detector parameters, and signal conversion parameters used in generating the test harmonic absorption curve from a signal produced by the detector. 11. An apparatus as in claim 9, wherein the operations performed by the controller further comprise promoting a field validation metric of the laser absorption spectrometer, the field validation metric comprising at least one of the difference between the test curve shape and the reference curve shape, an identification of the one or more operating and analytical parameters that were adjusted, and a value by which the one or more operating and analytical parameters were adjusted. 12. An apparatus as in claim 9, wherein the laser light source parameters comprise at least one of a temperature, an operating current, a modulation current, a ramp current, a ramp current curve shape, and a phase of the laser light source. 13. An apparatus as in claim 9, wherein the detector parameters comprise at least one of a gain and a phase setting of a detector circuit. 14. An apparatus as in claim 9, wherein the signal conversion parameters comprise at least one of a gain and a phase setting of the demodulating device. 15. An apparatus as in claim 8, wherein the comparing further comprises applying at least one of subtracting, dividing, cross correlation, curve fitting, and multivariable regression for one or more parts or the entire of the test curve and the reference curve, and computing one or more of the difference, the ratio, the mean square error (MSE), the coefficient of determination (R2), the cross correlation function/integral and the regression coefficients in the light intensity (i.e., the y-axis) and/or the wavelength (i.e. the x-axis) domain to quantify the difference between the test curve shape and the reference curve shape. 16. An apparatus as in claim 8, wherein the reference harmonic absorption curve comprises at least one of a calibration reference curve stored during calibration of the laser absorption spectrometer and a constructed curve comprising one or more mathematically combined stored calibration reference curves selected according to at least one of a composition of a background gas that the sample gas comprises and an expected concentration of a target analyte to be measured in the sample gas containing the background gas. 17. An apparatus as in claim 8, wherein the comparing further comprises applying a curve fitting algorithm to quantify the difference between the test curve shape and the reference curve shape. 18. An apparatus as in claim 1, wherein the light path into which the sample gas is directed during the sample analysis mode and into which the zero gas is directed during the validation mode passes through the validation cell at least once. 19. An apparatus as in claim 1, wherein the known amount of the analyte in the reference gas is a non-zero amount. 20. An apparatus as in claim 1, wherein the sample gas directed into the light path during the sample analysis mode and the zero gas directed into the light path during the validation mode are not contained within the validation cell. 21. A method comprising: comparing light intensity data with a stored data set representing at least one previous measurement in a validation mode of an absorption spectrometer; the light intensity data quantifying intensity of a light path generated by a light source and received at a detector during the validation mode of the absorption spectrometer, the validation mode comprising causing the light path to pass at least once through each of a zero gas and a reference gas, the reference gas being contained within a validation cell and comprising a known amount of a target analyte, the zero gas having at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source; anddetermining that a validation failure has occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount;wherein the comparing and the determining are performed by at least one system comprising computer hardware. 22. A method as in claim 21, wherein: the light source comprises a tunable or scannable laser of a laser absorption spectrometer, and the stored data set comprise a reference harmonic absorption curve of the laser absorption spectrometer, the reference harmonic absorption curve having a reference curve shape and comprising at least one of a first or higher order harmonic signal of a reference signal generated by the detector in response to the light path passing from the light source through the reference gas in the validation cell, the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;the light intensity data comprises a test harmonic absorption curve having a test curve shape; andthe predefined threshold amount comprises a predefined allowed deviation between the test curve shape and the reference curve shape. 23. A method as in claim 22, further comprising: adjusting one or more operating and/or analytical parameters of the laser absorption spectrometer to correct the test curve shape to reduce the difference between the test curve shape and the reference curve shape. 24. A method as in claim 23, wherein the one or more operating and/or analytical parameters of the laser absorption spectrometer comprise at least one of laser light source parameters, detector parameters, and signal conversion parameters used in generating the test harmonic absorption curve from a signal produced by the detector. 25. A method as in claim 24, wherein: the laser light source parameters comprise at least one of a temperature, an operating current, a modulation current, a ramp current, a ramp current curve shape during scanning and a phase of the laser light source; the detector parameters comprise at least one of a gain and a phase setting of a detector circuit; and the signal conversion parameters comprise at least one of a gain and a phase setting of the demodulating device. 26. An article comprising a non-transitory computer readable medium encoding instructions that, when executed by at least one processor, cause the at least one processor to perform operations comprising: comparing light intensity data with a stored data set representing at least one previous measurement in a validation mode of an absorption spectrometer; the light intensity data quantifying intensity of a light path generated by a light source and received at a detector during the validation mode of the absorption spectrometer, the validation mode comprising causing the light path to pass at least once through each of a zero gas and a reference gas, the reference gas being contained within a validation cell and comprising a known amount of a target analyte, the zero gas having at least one of known and negligible first light absorbance characteristics within a range of wavelengths produced by the light source; anddetermining that a validation failure has occurred if the first light intensity data and the stored data set are out of agreement by more than a predefined threshold amount. 27. An article as in claim 26, wherein: the light source comprises a tunable or scannable laser of a laser absorption spectrometer, and the stored data set comprise a reference harmonic absorption curve of the laser absorption spectrometer, the reference harmonic absorption curve having a reference curve shape and comprising at least one of a first or higher order harmonic signal of a reference signal generated by the detector in response to the light path passing from the light source through the reference gas in the validation cell, the reference harmonic absorption curve having been determined for the laser absorption spectrometer in a known or calibrated state;the light intensity data comprises a test harmonic absorption curve having a test curve shape; andthe predefined threshold amount comprises a predefined allowed deviation between the test curve shape and the reference curve shape.