6.1 Fundamentals
249
This chapter deals with the principles and fundamentals of Quantitative
Analysis, with special emphasis on the equipment and methodology used.
I 6.1.2 Analytical Properties
Chapter 2, which discusses analytical properties in a systematic manner, focusses
on Quantitative Analysis. Figure 2.2 is highly illustrative in this context; in fact, the
chemical metrological ranking it shows is based on numerical data (individual
results, means of results, the value held as true, etc.). Consequently, all the properties considered in Figs. 2.1 and 2.19 are relevant to the contents of this chapter.
A quantitative result can be thoroughly characterized in terms of the two capital analytical properties, viz. accuracy (closeness to the true value) and representativeness (the degree of consistency with the analytical problem addressed).
These properties in turn rest on basic analytical properties (precision, sensitivity,
selectivity and proper sampling); in fact, neither capital property can be realized
with poor levels of the basic ones. One must also consider the accessory properties
that characterize laboratory productivity (expeditiousness, cost -effectiveness,
personnel safety). Even more important, one must bear in mind the complementary and contradictory relationships among these properties (see Sect. 2.7).
As shown in Sect. 3.6.1, a quantitative analytical result can also be characterized
by its traceability (viz. its relationship to standards and the "history" of its production). In addition, it can be characterized by a specific uncertainty (viz. the
numerical range where it can be expected to fall at a given probability level), which
is a precision-related property. Finally, results are also appreciably affected in practice by robustness [viz. the ability to remain unaltered in response to slight changes in the experimental conditions of the chemical measurement process (CMP) J.
I 6.1.3 Equipment and Method Calibration
Proper use of suitable measuring standards is crucial in Quantitative Analysis;
without them, one would not be able to measure (or compare). All types of
standards (basic, chemical and analytical) depicted in Fig. 3.4, as well as the
different types of analytical chemical standards (Fig. 3.8), can be used for
quantitative purposes in the first two steps of a CMP.
One important application of standards is calibration of equipment and
methods (see Fig. 3.10).
The primary aim of equipment calibration is to ensure proper functioning of
a quantifying instrument (e. g. a balance, burette, spectrophotometer, polarograph, mass spectrometer) by using standards not containing the analyte (e.g.
transfer weights for a balance, a holmium filter for a UV-visible molecular
absorption spectrophotometer). The example describing the calibration of a
photometer in Box 3.3 is highly illustrative.
Method calibration in Quantitative Analysis is basically intended to establish
a clear-cut, unequivocal relationship between the instrument response and the
249
This chapter deals with the principles and fundamentals of Quantitative
Analysis, with special emphasis on the equipment and methodology used.
I 6.1.2 Analytical Properties
Chapter 2, which discusses analytical properties in a systematic manner, focusses
on Quantitative Analysis. Figure 2.2 is highly illustrative in this context; in fact, the
chemical metrological ranking it shows is based on numerical data (individual
results, means of results, the value held as true, etc.). Consequently, all the properties considered in Figs. 2.1 and 2.19 are relevant to the contents of this chapter.
A quantitative result can be thoroughly characterized in terms of the two capital analytical properties, viz. accuracy (closeness to the true value) and representativeness (the degree of consistency with the analytical problem addressed).
These properties in turn rest on basic analytical properties (precision, sensitivity,
selectivity and proper sampling); in fact, neither capital property can be realized
with poor levels of the basic ones. One must also consider the accessory properties
that characterize laboratory productivity (expeditiousness, cost -effectiveness,
personnel safety). Even more important, one must bear in mind the complementary and contradictory relationships among these properties (see Sect. 2.7).
As shown in Sect. 3.6.1, a quantitative analytical result can also be characterized
by its traceability (viz. its relationship to standards and the "history" of its production). In addition, it can be characterized by a specific uncertainty (viz. the
numerical range where it can be expected to fall at a given probability level), which
is a precision-related property. Finally, results are also appreciably affected in practice by robustness [viz. the ability to remain unaltered in response to slight changes in the experimental conditions of the chemical measurement process (CMP) J.
I 6.1.3 Equipment and Method Calibration
Proper use of suitable measuring standards is crucial in Quantitative Analysis;
without them, one would not be able to measure (or compare). All types of
standards (basic, chemical and analytical) depicted in Fig. 3.4, as well as the
different types of analytical chemical standards (Fig. 3.8), can be used for
quantitative purposes in the first two steps of a CMP.
One important application of standards is calibration of equipment and
methods (see Fig. 3.10).
The primary aim of equipment calibration is to ensure proper functioning of
a quantifying instrument (e. g. a balance, burette, spectrophotometer, polarograph, mass spectrometer) by using standards not containing the analyte (e.g.
transfer weights for a balance, a holmium filter for a UV-visible molecular
absorption spectrophotometer). The example describing the calibration of a
photometer in Box 3.3 is highly illustrative.
Method calibration in Quantitative Analysis is basically intended to establish
a clear-cut, unequivocal relationship between the instrument response and the