lecture 3 the metrological providing of the quantitative chemical analysis ass. n.i. burmas

LectureLecture 33

The metrological providing of the The metrological providing of the quantitative chemical analysisquantitative chemical analysis

assass. . NN..II. . BurmasBurmas

OutlineOutline

1. The basic metrological descriptions of an 1. The basic metrological descriptions of an analysis.analysis.

2. The statistical processing results of an 2. The statistical processing results of an analysis.analysis.

3. The methods valuation of regularity of an 3. The methods valuation of regularity of an analysis.analysis.

4. The metrological providing of quantitative 4. The metrological providing of quantitative chemical analysis.chemical analysis.

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1. The basic metrological descriptions 1. The basic metrological descriptions of an analysis.of an analysis.

The basic metrologic descriptions method of The basic metrologic descriptions method of analysis belong:analysis belong:

regularity;regularity; producibility;producibility; the coefficient of sensitiveness;the coefficient of sensitiveness; the lthe limitimit of exposure;of exposure; lower and upper llower and upper limitimitss of determination;of determination; selectivity.selectivity.

2. The statistical processing results of 2. The statistical processing results of an analysis.an analysis.

The selection is an aggregate statistically The selection is an aggregate statistically equivalent of results.equivalent of results.

The sThe sequence of processing:equence of processing:

1.1. Verification on the presence of rough errors Verification on the presence of rough errors by of Q-test:by of Q-test:

хх11, х, х22, х, х33, х, х44,…х,…хn-1n-1, x, xnn

.

1x

nx

1nx

nx

.exper.Q;

1x

nx

1x

2x

.exper.Q

If If QQexperexper.. QQcritical critical ,, then the result of then the result of

determination it costs to leave for determination it costs to leave for subsequent considerationsubsequent consideration

If If QQexperexper.. Q Qtheorettheoret..,, then the result of then the result of

determination needs to throw off.determination needs to throw off.

The theoretical values Q-test at The theoretical values Q-test at the different probabilitiesthe different probabilities

nn QQ0,900,90 QQ0,950,95

33 0,940,94 0,940,94

44 0,760,76 0,770,77

55 0,640,64 0,640,64

66 0,560,56 0,560,56

nn QQ0,900,90 QQ0,950,95

77 0,510,51 0,510,51

88 0,470,47 0,480,48

99 0,440,44 0,440,44

1010 0,410,41 0,420,42

2. Calculation the middle arithmetic to the 2. Calculation the middle arithmetic to the result of measurements:result of measurements:

3. 3. Calculation of the middleCalculation of the middle square square deviation:deviation:

;n

xx i

n

0i

1n)xx(

S2

i

4. 4. Calculate the Calculate the dispersion dispersion of of selectionselection SS22

55. . Calculation of the Calculation of the confidence intervalconfidence interval

n,it

nS

xx

The comparison selections of results of an The comparison selections of results of an analysisanalysis

The criterion of Fisher:The criterion of Fisher:

1. Calculation the dispersion of different 1. Calculation the dispersion of different series of measurementsseries of measurements andand

2. 2. Calculation the experimental criterion of Calculation the experimental criterion of

FisherFisher ( (must be must be SS1122SS22

22 ))

2

1S 2

2S

2

2

2

1

.exper. SS

F

If If FFexper.exper. F Ftheorettheoret, , than the difference than the difference

between dispersions is insignificant, it between dispersions is insignificant, it is possible to estimate difference is possible to estimate difference between between and and . . 1X

2X

Criterion of StudentCriterion of Student1. 1. Calculation of the weighed dispersion of two Calculation of the weighed dispersion of two

selectionsselections::

2.2. Calculation of the experimental value the Calculation of the experimental value the coefficient of Student:coefficient of Student:

If If tt tabletable..tt experexper.., , then consider thatthen consider that

and it is possible to unite two series of results and and it is possible to unite two series of results and conduct one statistical processing.conduct one statistical processing.

0XX21

2nn

S)1n(S)1n(S

21

222

211

2

.nn

nn

S

ххt

21

212

21.exper.

3. The methods valuation of regularity of an 3. The methods valuation of regularity of an analysis.analysis.

the method of standard specimens;the method of standard specimens; the method of change mass of the known the method of change mass of the known

quantity of the determined substance; quantity of the determined substance; the method of addition of the known the method of addition of the known

quantity of the determined substance quantity of the determined substance (the systematic error is proportional to (the systematic error is proportional to content of the determined substance content of the determined substance Δх = Δх = bbх)х)

the method of change of method analysisthe method of change of method analysis

4. The metrological providing of the quantitative 4. The metrological providing of the quantitative chemical analysis.chemical analysis.

The The chemical method haschemical method has::1.1. Metrological Metrological

descriptionsdescriptions regularity;regularity; producibility;producibility; the boundary of exposure;the boundary of exposure; lower and upper boundaris lower and upper boundaris

of determinationof determination ;; selectivity;selectivity; sensitivity;sensitivity;

2. Technical descriptions:2. Technical descriptions: the possibility of the possibility of

automation;automation;

distancedistance control;control; expressivity;expressivity; energocapacity;energocapacity;

The aThe analytical signals:nalytical signals: one-components (atomic-absorbcion one-components (atomic-absorbcion

spectroscopy)spectroscopy) many-components (sweepable many-components (sweepable

spectrophotometry)spectrophotometry)

The aThe analytical signalsnalytical signals : :

1.1. integralintegral

2.2. differential:differential: on the form (differential spectrophotometry) ; on the form (differential spectrophotometry) ; on the nature (gas chromatography with two on the nature (gas chromatography with two

columns, two-radiation spectrophotometer,).columns, two-radiation spectrophotometer,).

The sThe specificpecific ofof chemicalchemical analysisanalysis::1. Measured simultaneously often enough the 1. Measured simultaneously often enough the few quantities - contentses. That is why at first few quantities - contentses. That is why at first of all there is procedure of authentication with of all there is procedure of authentication with the use of standards.the use of standards.22. The measuring is carried by indirect . The measuring is carried by indirect personality: measured not quite number of personality: measured not quite number of particles , and certain parameters in the particles , and certain parameters in the chemical, physical and chemical and physical chemical, physical and chemical and physical methods of analysis. methods of analysis. 3. An analysis is complicated by the mutual-3. An analysis is complicated by the mutual-couplings of components.couplings of components.

The basic stages and the source errors of The basic stages and the source errors of chemical analysischemical analysis

1. The selection of middle (satis factory) 1. The selection of middle (satis factory) sample.sample.

2. The translation is in a form, comfortable for 2. The translation is in a form, comfortable for an analysis:an analysis:

previous enrichingprevious enriching chemical processingchemical processing often the special preparation of surfaceoften the special preparation of surface3. The dividing of components sample is into 3. The dividing of components sample is into

separate groups.separate groups.


4. The translation determined of component in 4. The translation determined of component in an analytically active form. an analytically active form.

5. The determination is measuring of physical 5. The determination is measuring of physical property. property.

6. An evaluation content of determined 6. An evaluation content of determined component is on the calibration chart or the component is on the calibration chart or the calibration dependence, the calculation of a calibration dependence, the calculation of a formula.formula.


7. Calculation and evaluation of 7. Calculation and evaluation of reliability results of an analysis.reliability results of an analysis.

8. The analysis (logical and 8. The analysis (logical and mathematical) of the got results and mathematical) of the got results and work of recommendations for work of recommendations for optimization of chemical analysis.optimization of chemical analysis.

4. The metrological providing of the quantitative 4. The metrological providing of the quantitative chemical analysis (QChA).chemical analysis (QChA).

The scientific basis of the metrological The scientific basis of the metrological providing of quantitative chemical providing of quantitative chemical analysis are analysis are theoretical and theoretical and methodical positions of a metrology methodical positions of a metrology and the analytical chemistryand the analytical chemistry..

The metrological providing of QChA includes The metrological providing of QChA includes for it self the next types of worksfor it self the next types of works::

1)1) establishment of the norms errors of results of establishment of the norms errors of results of QChA;QChA;

2)2) recreation and transmission of the sizes units recreation and transmission of the sizes units of physical sizes, which characterize of physical sizes, which characterize composition of substances or their properties composition of substances or their properties which are functionally related with which are functionally related with composition of these substancescomposition of these substances ; ;

3)3) the development of standard specimens, the development of standard specimens, attested mixtures, standard reference attested mixtures, standard reference information and recommended standard information and recommended standard information.information.


4) the providing of the same type uses is in QChA 4) the providing of the same type uses is in QChA of means measurings at development, to the of means measurings at development, to the issue in an appeal, exploitation and repair and issue in an appeal, exploitation and repair and their the accordance; their the accordance;

5) the standard charts or other normative 5) the standard charts or other normative documents;documents;

6) the providing methods of QChA of fulfilment 6) the providing methods of QChA of fulfilment necessary of the metrological requirements;necessary of the metrological requirements;

7) the metrological control of QChA.7) the metrological control of QChA.


8) development complex of normative 8) development complex of normative documents, positions, rules on providing documents, positions, rules on providing of necessary exactness of results of of necessary exactness of results of QChA;QChA;

9) the state supervision and known control 9) the state supervision and known control after the status of QChA, including after the status of QChA, including metrological attestation of the analytical metrological attestation of the analytical laboratories.laboratories.

The metrological control of QChA is The metrological control of QChA is conducted by:conducted by:

the inside-laboratory control of exactness results of the inside-laboratory control of exactness results of QChA on procedure, regulated in the methodical ofQChA on procedure, regulated in the methodical of

QChA ; QChA ; the inside-laboratory statistical control of exactness of the inside-laboratory statistical control of exactness of

the results of QChA on procedure, regulated in the the results of QChA on procedure, regulated in the particular branch spheres on the control exactness of particular branch spheres on the control exactness of results of QChA; results of QChA;

an external control the quality of work analytical an external control the quality of work analytical laboratories on procedure, regulated in the particular laboratories on procedure, regulated in the particular branch documents on a control of the exactness results branch documents on a control of the exactness results of QChA and the documents of a national standard.of QChA and the documents of a national standard.

Thanks you for attention!

lecture 3 the metrological providing of the quantitative chemical analysis ass. n.i. burmas

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