JP2004020323A - Measuring instrument provided with function for finding uncertainty - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a working time for finding composition uncertainty for a measured data to be displayed. <P>SOLUTION: Uncertainty Uc [appliance tolerance] of appliance tolerance in a measuring part 2, and uncertainty Uc [appliance operation] of an appliance operation are held in a known uncertainty holding part 4. A calibration curve uncertainty calculating part 6 calculates uncertainty Uc[calibration curve] of a calibration curve when the measuring part 2 measures a standard sample. When an unknown sample is measured by the measuring part 2, an unknown sample uncertainty calculating part 8 calculates uncertainty Uc [unknown sample] for an unknown sample measured value therein, a composition uncertainty calculating part 10 composes the uncertainties Uc [appliance tolerance], Uc [appliance operation], Uc[calibration curve] and Uc [unknown sample], to calculate composition uncertainty Uc, and a display part 12 displays the calculated composition uncertainty Uc together with the measured value of the unknown sample. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a measuring apparatus such as a liquid chromatograph (LC), a gas chromatograph (GC), and a mass spectrometer (MS) used in the field of quantitatively measuring the stoichiometry or physical quantity of a sample such as a solution or a gas, and in particular, The present invention relates to a measurement apparatus for determining a quantitative value of a target substance by applying a result obtained by measuring a sample to a calibration curve.
[0002]
[Prior art]
In recent years, in the field of analysis, obtained data is output or displayed with an uncertainty value attached thereto.
The uncertainty is calculated as an integrated value of various uncertainties, such as an uncertainty due to the operation of the instrument by the analyst, an error due to tolerance of the instrument itself, and an error due to data fluctuation of the measuring device. In other words, the uncertainty can be said to be an index for clarifying the degree of reliability of the result.
[0003]
The calculation method for that has been established by statistics and the like, but if this value is to be calculated, it will be quite a difficult task. In particular, all uncertainties, including the uncertainty of the data itself due to fluctuations in the data of the measuring device (also called noise errors, data variations, or repeatability errors) are calculated and combined to form the final combined uncertainty. The work to be reflected in the measurement results is a time-consuming work because it is calculated by spreadsheet software Excel or the like using a computer.
Moreover, since there is a time difference between the display of the measurement data and the display of the calculation result of the uncertainty, the person performing the measurement cannot immediately know the reliability of the measurement data.
[0004]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to reduce as much as possible the work time for obtaining and displaying a combined uncertainty representing the reliability of measurement data.
[0005]
[Means for Solving the Problems]
In order to achieve this object, the present invention has a function of automatically calculating and displaying the uncertainty in the measuring apparatus itself, and is configured as shown in FIG.
Reference numeral 2 denotes a measuring unit for quantitatively measuring the stoichiometry or physical quantity of the sample. Reference numeral 4 denotes a known uncertainty holding unit which holds the uncertainty Uc [instrument tolerance] of the instrument tolerance of the measuring unit 2 and the uncertainty Uc [instrument operation] of the instrument operation. Reference numeral 6 denotes a calibration curve uncertainty calculation unit that calculates the uncertainty Uc [calibration curve] of the calibration curve when the measuring unit 2 measures the standard sample. Reference numeral 8 denotes an unknown sample uncertainty calculation unit, which calculates the uncertainty Uc [unknown sample] for the unknown sample measurement value when the measuring unit 2 measures the unknown sample. Reference numeral 10 denotes a combined uncertainty calculation unit that combines these uncertainties Uc [instrument tolerance], Uc [instrument operation], Uc [calibration curve], and Uc [unknown sample] to calculate the combined uncertainty Uc. The display unit 12 displays the combined uncertainty Uc calculated by the combined uncertainty calculation unit 10 together with the measured value of the unknown sample.
[0006]
The standard deviation is generally used as the uncertainty. Alternatively, relative uncertainty can be used. The relative uncertainty is a value obtained by dividing a standard deviation by an average value, and is also called a relative standard deviation or a coefficient of variation.
[0007]
When each uncertainty is expressed in terms of standard deviation or relative standard deviation, the combined uncertainty is called the combined standard uncertainty. An example of a method of obtaining the combined standard uncertainty is a sum of squares (square of squares). Each uncertainty is obtained as a standard deviation or a relative standard deviation, and the squared values of the sums are added together. It is what was asked.
[0008]
The uncertainty of the instrument tolerance Uc [instrument tolerance] is determined in advance by the measuring device, and is estimated based on the measurement result of the reference material or the data of the known measurement result, or based on the physical constant or the like. Is the uncertainty gained by
[0009]
The instrument operation uncertainty Uc [instrument operation] is uncertainty depending on the skill level of the operator, and can be statistically evaluated based on a series of repeated measurements.
[0010]
The uncertainty of instrument tolerance Uc [instrument tolerance] and the uncertainty of instrument operation Uc [instrument operation] are determined in advance, and are set in the known uncertainty holding unit 4 by being input from an input unit such as a keyboard or a panel. Have been.
[0011]
The calibration curve uncertainty Uc [calibration curve] can be obtained by measuring the standard sample a plurality of times and measuring the dispersion of the data when measuring the standard sample to obtain the calibration curve data. Can be determined as the relative standard deviation of
[0012]
The unknown sample uncertainty Uc [unknown sample] can be obtained from a variation in data when the unknown sample is repeatedly measured a plurality of times. The unknown sample uncertainty can also be determined as a relative standard deviation based on data from a plurality of repeated measurements.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is realized by an analyzer such as a liquid chromatograph, and the calibration curve uncertainty calculator 6, the unknown sample uncertainty calculator 8 and the synthetic uncertainty calculator 10 shown in FIG. It is realized by a provided CPU (central processing unit). The known uncertainty holding unit 4 for holding the instrument uncertainty Uc [instrument tolerance] and the instrument uncertainty Uc [instrument operation] is realized by a storage device provided in the control unit of the analyzer. .
[0014]
The operation of this embodiment will be described with reference to the flowchart of FIG.
On the display screen of the analyzer realizing the present invention, an "uncertainty condition setting screen" is displayed, the type M of the standard sample, the number of measurements (n times) for observing the repetition error, and the uncertainty Uc of the instrument tolerance [ The device tolerance] and the uncertainty Uc [device operation] of the device operation can be set by inputting from a keyboard.
[0015]
The uncertainty is described as being expressed as a standard deviation.
In operating this analyzer, the values of the standard uncertainty Uc [instrument operation] and the uncertainty Uc [instrument tolerance] due to the tolerance of the instrument itself are calculated in advance.
[0016]
First, those values, that is, the standard uncertainty Uc [instrument operation] in the appliance operation and the uncertainty Uc [instrument tolerance] due to the tolerance of the appliance itself are input in advance on the "uncertainty condition setting screen". Further, the user inputs the type M of the standard sample and the number of measurements (n times) for checking the repetition error on the “uncertainty condition setting screen” on the display screen.
[0017]
Next, a calibration curve for converting a value measured by the measuring unit into a value to be obtained, such as a concentration, is created. In order to create the calibration curve, data is measured n times for each of M standard samples, and a calibration curve of the M data is obtained from an average value of the n data. Then, the standard uncertainty Uc [calibration curve] of the calibration curve is calculated in consideration of n variations of each of the M standard samples.
[0018]
Next, proceed to the measurement of the unknown sample. The unknown sample 1, which is the first unknown sample, is repeatedly measured n times, and the standard uncertainty Uc [unknown 1] due to the fluctuation of the data of the unknown sample 1 itself (the fluctuation error due to the n-times repeated measurement) is calculated from the measurement result. You.
[0019]
Then, the combined standard uncertainty Ucl, which is the final index of the uncertainty of the unknown sample 1, is calculated by software using the CPU from Uc [instrument operation], Uc [instrument tolerance], Uc [calibration curve] and Uc [unknown 1]. Required by
[0020]
For the second unknown sample 2, the measurement is performed n times in the same manner, the standard uncertainty Uc [unknown 2] of the unknown sample 2 is calculated, Uc [instrument operation], Uc [instrument tolerance], and Uc [calibration]. Line] to calculate the composite standard uncertainty Uc2.
[0021]
Similarly, the unknown samples to be measured are measured n times in sequence, and the calibration curve data is applied to the measured values of each unknown sample to determine quantitative values such as concentration, and the synthesized standard uncertainty Uc of each unknown sample is determined. Are calculated one after another.
[0022]
FIG. 3 shows an example in which the calculated standard uncertainty value is displayed together with the calculated density value. When the uncertainty is represented by the standard deviation, and when the distribution is a normal distribution, when the standard deviation is represented by σ, the probability of being within ± 1σ is about 68%. The example of FIG. 3 shows the combined standard uncertainty ± σ as the combined uncertainty. Therefore, assuming that the distribution is a normal distribution, it means that the probability that a true value exists within (quantitative value) ± (uncertainty) shown in FIG. 3 is about 68%.
[0023]
As the value of the combined uncertainty displayed together with the measurement result such as the density value, an extended uncertainty obtained by doubling the combined standard uncertainty may be used. When the distribution is a normal distribution, the probability that the true value exists within the mean ± 2σ is about 95%. Therefore, if the extended uncertainty is attached and displayed, the (quantitative value) ± (extended Uncertainty) means 95% reliability.
[0024]
If the uncertainty obtained by multiplying the combined standard uncertainty by three is used, if the distribution is a normal distribution, the probability of being within ± 3σ of the average is about 99.7%. Value) ± (uncertainty) means about 99.7% reliability.
[0025]
【The invention's effect】
Until now, the composite uncertainty had to be calculated and output by itself after measurement. However, in the present invention, the uncertainty Uc [instrument tolerance] of the instrument tolerance and the uncertainty Uc [instrument operation] of the instrument operation are set. If this is done, the uncertainty Uc [calibration curve] of the calibration curve when the standard sample is measured by the calibration curve uncertainty calculation unit is calculated, and the unknown sample measurement when the unknown sample is measured by the unknown sample uncertainty calculation unit. The uncertainty Uc [unknown sample] for the value is calculated, and these uncertainties are combined by the combined uncertainty calculation unit to calculate the combined uncertainty Uc, and the calculated combined uncertainty Uc is displayed on the display unit. Since the measurement value is displayed together with the measured value, the “uncertainty” of the unknown sample is calculated and displayed at the same time as the measurement of the unknown sample is completed. Therefore, the following effects can be achieved.
{Circle around (1)} The amount of work required to calculate the combined uncertainty Uc is considerably reduced as compared with the related art.
(2) Since the uncertainty is obtained immediately after the measurement, the analyst can judge the reliability of the measured value in real time.
(3) In the future, it is required that the request analysis company attach uncertainty to the data and output it, but since it can be calculated efficiently, there is a large contribution in terms of cost.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating the present invention.
FIG. 2 is a flowchart illustrating the operation of one embodiment.
FIG. 3 is a diagram showing an example of a display screen of a measurement result.
[Explanation of symbols]
2 Measuring unit 4 Known uncertainty holding unit 6 Calibration curve uncertainty calculating unit 8 Unknown sample uncertainty calculating unit 10 10 is combined uncertainty calculating unit 12 Display unit

Claims (2)

A measuring unit for quantitatively measuring the stoichiometry or physical quantity of the sample,
A known uncertainty holding unit that holds the uncertainty of instrument tolerance Uc [instrument tolerance] and the uncertainty of instrument operation Uc [instrument operation] of the measurement unit;
A calibration curve uncertainty calculation unit that calculates the uncertainty Uc [calibration curve] of the calibration curve when the measurement unit measures a standard sample;
An unknown sample uncertainty calculation unit that calculates the uncertainty Uc [unknown sample] for the unknown sample measurement value when the measurement unit measures the unknown sample;
A combined uncertainty calculator that combines these uncertainties to calculate a combined uncertainty Uc;
A display unit for displaying the combined uncertainty Uc calculated by the combined uncertainty calculation unit together with the measured value of the unknown sample. The measuring apparatus according to claim 1, wherein the uncertainty calculated by the combined uncertainty calculator is a combined standard uncertainty based on a standard deviation.

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