1. Basics of Analytical Chemistry 2018
1.1. Analytical chemistry, chemical analysis and their tasks
“ANALYTICAL CHEMISTRY IS WHAT ANALYTICAL CHEMISTS DO.”
This quote is attributed to C. N. Reilly (1925-1981) on receipt of the 1965 Fisher Award in
Analytical Chemistry. Reilly, who was a professor of chemistry at the University of North
Carolina at Chapel Hill, was one of the most influential analytical chemists of the last half of
the twentieth century.
Analytical chemistry is often described as the area of chemistry responsible for
characterizing the composition of matter, both qualitatively and quantitatively. But this
description is misleading. Most chemists routinely make qualitative and quantitative
measurements. For this reason, some scientists suggest that analytical chemistry is not a
separate branch of chemistry, but simply the application of chemical knowledge. In fact, you
probably have performed quantitative and qualitative analyses in other chemistry courses.
Defining analytical chemistry as the application of chemical knowledge ignores the
unique perspective that analytical chemists bring to the study of chemistry. The craft of
analytical chemistry is not in performing a routine analysis on a routine sample, which more
appropriately is called chemical analysis, but in improving established analytical methods, in
extending existing analytical methods to new types of samples, and in developing new
analytical methods for measuring chemical phenomena.
Analytical chemistry is a science that investigates and improves a methods of
Content of analytical chemistry – surroundings chemical compositions and
structures determination methods and their theoretical foundations.
Tasks of analytical chemistry - improve present and develop novel scientificaly
reasonable analytical methods according to nowaday requirements.
Chemical analysis involves practical determination of the chemical composition and
structure of various objects using analytical chemistry methods.
SEVEN STAGES OF AN ANALYTICAL METHOD
1. Conception of analytical method (birth).
2. Successful demonstration that the analytical method works.
3. Establishment of the analytical method’s capabilities.
4. Widespread acceptance of the analytical method.
5. Continued development of the analytical method leads to significant improvements.
6. New cycle through steps 3–5.
7. Analytical method can no longer compete with newer analytical methods (death).
Steps 1–3 and 5 are the province of analytical chemistry; step 4 is the realm of chemical
Here is one example of this distinction between analytical chemistry and chemical analysis. Mining
engineers evaluate the value of an ore by comparing the cost of removing the ore with the value of its contents.
To estimate its value they analyze a sample of the ore. The challenge of developing and validating an appropriate
quantitative analytical method is the analytical chemist’s responsibility. After its development, the routine, daily
application of the analytical method is the job of the chemical analyst.
Another distinction between analytical chemistry and chemical analysis is that analytical chemists work
to improve and extend established analytical methods. For example, several factors complicate the quantitative
analysis of nickel in ores, including nickel’s unequal distribution within the ore, the ore’s complex matrix of
silicates and oxides, and the presence of other metals that may interfere with the analysis. Figure 1.1 shows a
schematic outline of one standard analytical method in use during the late nineteenth century. The need for many
reactions, digestions, and filtrations makes this analytical method both time-consuming and difficult to perform
Figure 1.1. Fresenius’ analytical scheme for the gravimetric analysis of Ni in ores. Note that the mass
of nickel is not determined directly. Instead, Co and Ni are isolated and weighed (mass A), and then Co is
isolated and weighed (mass B). The timeline shows that after digesting a sample, it takes approximately 44 hours
to complete an analysis. This scheme is an example of a gravimetric analysis in which mass is the important
The development, in 1905, of dimethylglyoxime (dmg), a reagent that selectively precipitates Ni2+
, led to an improved analytical method for the quantitative analysis of nickel. The resulting analysis, as
shown in Figure 1.2, requires fewer manipulations and less time after completing the sample’s dissolution.
By the 1970s, flame atomic absorption spectrometry replaced gravimetry as the standard method for
analyzing nickel in ores, resulting in an even more rapid analysis. Today, the standard analytical method utilizes
an inductively coupled plasma optical emission spectrometer.
Figure 1.2. Gravimetric analysis for Ni in ores by precipitating Ni(dmg)2. The timeline shows that it
takes approximately four hours to complete an analysis after digesting the sample, which is 10x shorter than for
the method in Figure 1.1. The factor of 0.2301 in the equation for %Ni accounts for the difference in the formula
weights for Ni and Ni(dmg)2
Analytical chemistry is generaly devided in two parts:
Qualitative analysis – establishes the chemical identity of the species in the sample.
Quantitative analysis – determines the relative amounts of these species, or analytes, in
In some literature also structureanalysis is revealed. Structureanalysis allows to determine
structure of the substance.
Most common analytical chemistry is characterized by two basic questions – WHAT?
(qualitative analysis) and HOW MUCH? (quantitative analysis)
Analytical chemistry is one of the most importants chemistry branches. As chemical
elements form totally everything what is arround as, what we use, consume and even eat, then
knowing their chemical composition in many cases is daily necessary. Analytical chemistry
plays a vital role practically in all aspects of chemistry, for example, agricultural,
environmental, industrial, pharmaceutical, cosmetic, forensic expertise etc. Moreover, it is
closely related to other sciences (Fig. 1.3.).
Daily applications of analytical chemistry is, for example, measure of quantities of
hydrocarbons, nitrogen oxides, and carbon monoxide present in automobile exaust gases to
determine the effectiveness of smog-control devices; quantitative determination of nitrogen in
foods establishes their protein content and thus their nutritional value; the concentration of
oxygen and carbon dioxide are determined in millions of blood samples every day and used to
diagnose and treat illnesses, analysis of steel during its production permits adjustment in the
concentrations of such elements as carbon, nickel, and chromium to achieve a desired
strenght, hardness, corrosion resistance and ductility; farmers tailor fertilization and irrigation
schedules to meet changing plant needs during the growing season, gauging these needs from
quantitative analysis of the plants and the soil in which they grow.
Fig. 1.3. The relationship between analytical chemistry, other branches of chemistry, and the other sciences. The
central location of analytical chemistry in the diagram signifies its importance and the breadth of its interactions
with many other disciplines
1.2.Physical, chemical and biological methods of chemical analysis
Determination methods of substances chemical composition are based on the
properties of these substances. If only substances physical properties are used in
determination, it is called physical method of chemical analysis. Individual, pure substances
can be identified, for example, by their color, density, refractive index.
Chemical methods uses characteristic chemical reactions – formation of different
color precipitates, occurence of crystals of distinctive form, colorful complex compound
formation, release of gaseous compounds etc.
Biological methods – they use living organisms (microbes, small fish) and study their
behavior or activity.
Biochemical methods – the study of biological objects using chemical methods.
1.3. Major, minor, trace and ultratracecomponents in sample
Samples in analysis allways cosists of many components. Usually they are mechanical
mixtures or solutions of different substances.
Also, individual substances, which are usually considered as chemically pure, actually
contain many impurities, because absolutely pure substances practically doesn’t exist.
Depending on the mass fraction (wt%) of component in the sample, the components are
divided into major (>1 wt%), minor (0.01-1 wt%), trace (10-7
-0.01 wt%) and ultratrace
Determination of the major components is usually easier and simpler than
determination of minor, trace and especially ultratrace components. Determination of minor
and finer components requires very sensitive equipment and methods. Often minor
components are separated from the major components before detection. During analysis,
especially pure reagents must be used to avoid additional unnecessary impurities in the
sample. In the case of minor components, there are also increased requirements for the
materials from which the laboratory vessels are made and the purity of the laboratory air.
Determination of minor components is expensive, but it can play a vital role in controlling the
quality of many objects, for example, in the determination of nutrients in food. High purity
materials, for example, are used in nuclear energy, in the production of semiconductors, in the
formation of certain responsible structures.
1.4.Macro-, meso-, micro- and ultramicro analysis
Depending on the object mass needed for analysis, analysis methods are divided into
macro (>0.1 g), meso (10 mg–100 mg), micro (0.1 mg–10 mg), and ultramicro (< 0.1 mg).
Historically, the oldest method, of course, is macro-analysis, which is also used today to
determine the quantitative composition of objects, however, most often meso-analysis and
micro-analysis are used, especially in determinationof the qualitative composition. If micro-
analysis is used, it minimizes the mass of object needed for analysis (in comparison with
macro-analysis), alsovolume of necessary reagents is smaller; it is very important especially
in cases where the subject and/or reagents being analyzed are expensive or deficient. Micro-
analysis is often a faster analysis method than macro-analysis, but the results of quantitative
microanalysis may be less precise, as relative errors can be as high as a few tens of percent.
1.5.Selective and systematic analysis
Reagents used in chemical analysis are divided into specific, selective and group
Specific reagents at certain conditions react with only one ion of the substance and can
be used to identify this ion. Selective reagents reacts with a few ions, while group reagents
react with a certain group of ions. In qualitative analysis to identify separate ions, the most
useful would be specific reagents, which could make the procedure of analysis very simple.
Unfortunately ideal specific reagents practically doesn’t exist, thereby to identify each ion
selective reagents must be used. In this case specific reagent reacts not only with ion of
interest, but also with some other ion (interference or interfering ion) if this ion is present in
1.1. Table. Scheme of cation systematic analysis
The mixture of cations + HCl
The remaining ions in the solution + H2S, pH 0,5
In the precipitates:
(PbS), HgS, CuS,
CdS, Bi2S3, SnS2,
The remaining ions in the solution + H2SO4 +
The remaining ions in the
solution + H2S, pH 9...10
CoS, NiS, ZnS,
(1. group) (2. group) (3. group) (4. group) (5. group)
If there is a conviction that the interference in the analyte solution is not present at all,
or if its reaction with the used reagent can be prevented by linking it to a stable complex or
changing the degree of oxidation, then, with suitable selective reagents, it is possible to
arbitrarily search for all the components of the solution to be analyzed. Such analysis is called
Table 1.2. Separation of 1. group (hydrochloric acid) cations
AgCl, Hg2Cl2,PbCl2 + H2O (with heating)
In the precipitates: AgCl + Hg2Cl2
+ konc. NH3
In the precipitates: H2NHgCl + Hg
Previously, when the possibilities for preventing interferences were not so extensive, it
was difficult to perform a qualitative analysis. In order to solve the problem, Swedish chemist
T. Bergman laid the foundations for a systematic analysis of metal ions. From the solution to
be analyzed, he suggested to separate gradually the individual groups of substances, using the
appropriate reagents. Within the group, the ions are still separated from each other and only
then they are identified, which is no longer so difficult. Over the years, many variants of
systematic analysis have been developed, of which the most popular version of the cationic
group separation is given in 1.1. Table, but the separation of cations within a single group is
shown in Table 1.2. In general, systematic analysis is labor-intensive, and the ions in low
concentration may not be able to reach the corresponding group ("get lost") due to
coprecipitation, so the method is not ideal
1.6.Masking, elimination and separation of interferences in the sample
As previously mentioned, there are no ideal specific methods for identification and
quantifying the components, therefore, the mutual interfering impactof different components
should always be considered. The effects of interfering ions can be eliminated by various
techniques, which are basically divided into masking and separation techniques.
The most comfortable possibility how to avoid impact of interferences is to
immobilize, or chemically bind the interefence as a complex that no longer contributes
to or attenuates the signal from the analyte. Clearly, a masking agent must not affect
the behavior of the analyte significantly. The most common masking agents are
cyanide ions, fluoride ions, phosphate ions, as well as many organic compounds
(thiocarbamides, organic oxycarboxylic acid, etc.).
In some cases the influence of interferences is prevented by precipitation.
Precipitation, in which the analyte or interference is removed from a solution
selectively as an insoluble species, is one of the oldest methods for dealing with
interferences in an analytical procedure. For example, when calcium is determined by
complexometric titration, magnesium ions (interference) at pH 12...13 are precipitated
in form of Mg(OH)2which at given conditions practically doesn’t react with
The impact of interferences can be also eliminated by changing the oxidation state of
elements. For example, iron (III) ions, which presence encumber indentifying and
determination of many ions, can be reduced to less disturbing iron (II) ions.
If masking techniques are not applicable, interferences are precipitated and separated
from the solution. For example, in the indetification of magnesium and aluminium, there is no
reagents selective enough. Thereby, when magnesium ions are identified, interferences are
separated in groups at pH 9...10 in form of insoluble sulfides and hydroxides. Magnesium
ions which remain in the solution, then can be easy proved. Meanwhile aluminium is
separated from other ions in form of aluminates if interferences are precipitated from strongly
alkaline solutionas hydroxides and carbonates.
The most universal method for separation of interferences is chromatographic
separation. For example, nickel, cobalt and copper ions with organic reagent called
ditiooxamide form respectively blue, orange and blackened green complex compounds. If
these three ions at the same time are present in the solution, it is hard to identify them, but
applying technically very simple chromatographic separation technique with filter paper, each
ion will form a characteristic colorful plot on peace of filter paper.
Other separation techniques (filtration, distillation, extraction, etc.) will be viewed
1.7. General and Phase Analysis
A general analysis determines the total content of an element in the sample. During
phase analysis it is determined in what form this element exsists – pure, salt, hydroxide etc
and what is compunds molecular formula. In many cases, phase analysis is of great practical
importance. For example, zinc dust sold in laboratories used as a reducing agent contains not
only fine dispersed metallic zinc but also zinc oxide and carbonate impurities that are not
reducing agents. These impurities are determined by treating the sample with a solution
containing NH4Cl and NH3. The impurities dissolve, but metallic zinc is practically insoluble.
Another example. In steel carbon may be in free form (graphite), and it can be binded
with iron as a cementite Fe3C. The overall analysis determines the total carbon content by
combustion of the sample and measurement of the volume of CO2 produced. In the phase
analysis, the surface of the sample is abraded, carefully polished and then treated with acids.
The surface is then wached on a microscope and, after microscopic scans, the corresponding
phase content in the alloy is evaluated. The form of the carbon in the alloy strongly affects the
properties and uses of the alloy.
1.8. Analytical signal, its intensity
Various substances differ from each other by composition, structure, physical and
chemical properties. Most of properties can be used to learn about qualities, which distinguish
substance from others. These qualities are analytical signals. Occurance of signal points to
qualitative composition, while intensity of the signal gives quantitative coposition.
Substance properties are divided in extensive and intensive. Extensive properties
doesn’t depend on amount of substance (density, boiling temp., melting temp.) and they can
be used only in qualitative determination. Intensive properties depend on amount of the
substance (mass, volume, absorbance of electromagnetic radiation and its emission) and they
give opportunity to determine also quantitative composition.
1.9.Selecting an Analytical Method
A method is the application of a technique to a specific analyte in a specific matrix
(object). We can develop an analytical method for determining the concentration of lead in
drinking water using any of the techniques mentioned in the previous section. A gravimetric
method, for example, might precipitate the lead as PbSO4 or PbCrO4, and use the precipitate’s
mass as the analytical signal. Lead forms several soluble complexes, which we can use to
design a complexation titrimetric method. As shown in Figure 1.3., we can use graphite
furnace atomic absorption spectroscopy to determine the concentration of lead in drinking
water. Finally, the availability of multiple oxidation states (Pb0
electrochemical methods feasible.
The requirements of the analysis determine the best method. In choosing a method,
consideration is given to some or all the following design criteria: accuracy, precision,
sensitivity, selectivity, robustness, ruggedness, scale of operation, analysis time, availability
of equipment, and cost.
Accuracy is how closely the result of an experiment agrees with the “true” or expected
result (since it is unlikely that we know the true result, we use an expected or accepted result
when evaluating accuracy. For example, we might use a reference standard, which has an
accepted value, to establish an analytical method’s accuracy). We can express accuracy as an
EA = xi – xt
or as a percentage relative error, %
A method’s accuracy depends on many things, including the signal’s source, and the
ease of handling samples without loss or contamination. In general, methods relying on total
analysis techniques, such as gravimetry and titrimetry, produce results of higher accuracy
because we can measure mass and volume with high accuracy.
When a sample is analyzed several times, the individual results are rarely the same.
Instead, the results are randomly scattered. Precision is a measure of this variability. The
closer the agreement between individual analyses, the more precise the results. For example,
in determining the concentration of K+
in serum the results shown in Figure 1.4(a) are more
precise than those in Figure 1.4(b).
It is important to understand that precision does not imply accuracy. That the data in
Figure 1.4(a) are more precise does not mean that the first set of results is more accurate. In
fact, neither set of results may be accurate. A method’s precision depends on several factors,
including the uncertainty in measuring the signal and the ease of handling samples
reproducibly. In most cases we can measure the signal for a total analysis method with a
higher precision than the corresponding signal for a concentration method.
The difference between accuracy and precision can be easier understand by using a target in Fig. 1.5.
Fig. 1.5. Results in the case of A are neither accurate nor precise. In B results are precise but no
accurate. In C results are more accurate (the same distance from the center) but not precise. The case D is ideal
because results are accurate and precise.
The ability to demonstrate that two samples have different amounts of analyte is an
essential part of many analyses. A method’s sensitivity is a measure of its ability to establish
that such differences are significant. Sensitivity is often confused with a method’s detection
limit, which is the smallest amount of analyte that we can determine with confidence.
Fig.1.4. Two determinations
of the concentration of K+
in serum, showing the effect
of precision on the
distribution of individual
results. The data in (a) are
less scattered and, therefore,
more precise than the data
1.9.4.Specificity and Selectivity
An analytical method is specific if its signal depends only on the analyte. Although
specificity is the ideal, few analytical methods are completely free from the influence of
Selectivity is a measure of a method’s freedom from interferences. The selectivity of a
method for the interferent relative to the analyte is defined by a selectivity coefficient, KA,I
which may be positive or negative depending on the sign of k1 (signal of interferent) and kA
(signal of analyte). The selectivity coefficient is greater than +1 or less than –1 when the
method is more selective for the interferent than for the analyte.
When a method’s signal is the result of a chemical reaction—for example, when the
signal is the mass of a precipitate—there is a good chance that the method is not very
selective and that it is susceptible to interferences. Problems with selectivity also are more
likely when the analyte is present at a very low concentration.
1.9.5. Robustness and Ruggedness
For a method to be useful it must provide reliable results. Unfortunately, methods are
subject to a variety of chemical and physical interferences that contribute uncertainty to the
analysis. When a method is relatively free from chemical interferences, we can use it on many
analytes in a wide variety of sample matrices. Such methods are considered robust.
Random variations in experimental conditions also introduces uncertainty. If a
method’s sensitivity, k, is too dependent on experimental conditions, such as temperature,
acidity, or reaction time, then a slight change in any of these conditions may give a
significantly different result. A rugged method is relatively insensitive to changes in
1.9.6. Scale of Operation
Another way to narrow the choice of methods is to consider three potential limitations:
the amount of sample available for the analysis, the expected concentration of analyte in the
samples, and the minimum amount of analyte that produces a measurable signal. Collectively,
these limitations define the analytical method’s scale of operations.
1.9.7. Equipment, Time, and Cost
Finally, we can compare analytical methods with respect to equipment needs, the time
to complete an analysis, and the cost per sample. Methods relying on instrumentation are
equipment-intensive and may require significant operator training. For example, the graphite
furnace atomic absorption spectroscopic method for determining lead in water requires a
significant capital investment in the instrument and an experienced operator to obtain reliable
results. Other methods, such as titrimetry, require less expensive equipment and less training.
The time to complete an analysis for one sample is often fairly similar from method to
method. This is somewhat misleading, however, because much of this time is spent preparing
solutions and gathering together equipment. Once the solutions and equipment are in place,
the sampling rate may differ substantially from method to method. Additionally, some
methods are more easily automated. This is a significant factor in selecting a method for a
laboratory that handles a high volume of samples.
The cost of an analysis depends on many factors, including the cost of equipment and
reagents, the cost of hiring analysts, and the number of samples that can be processed per
hour. In general, methods relying on instruments cost more per sample then other methods.
1.9.8.Making the Final Choice
Unfortunately, the design criteria discussed in this section are not mutually
independent. Working with smaller samples or improving selectivity often comes at the
expense of precision. Minimizing cost and analysis time may decrease accuracy. Selecting a
method requires carefully balancing the design criteria. Usually, the most important design
criterion is accuracy, and the best method is the one giving the most accurate result. When the
need for results is urgent, as is often the case in clinical labs, analysis time may become the
In some cases it is the sample’s properties that determine the best method. A sample
with a complex matrix, for example, may require a method with excellent selectivity to avoid
interferences. Samples in which the analyte is present at a trace or ultratrace concentration
usually require a concentration method. If the quantity of sample is limited, then the method
must not require a large amount of sample.
Determining the concentration of lead in drinking water requires a method that can
detect lead at the parts per billion concentration level. Selectivity is important because other
metal ions are present at significantly higher concentrations. A method using graphite furnace
atomic absorption spectroscopy is a common choice for determining lead in drinking water
because it meets these specifications. The same method is also useful for determining lead in
blood where its ability to detect low concentrations of lead using a few microliters of sample
are important considerations.
1.10. Absolute and relative methods of quantitative analysis
The intensity of the analytical signal indicates the amount (concentration) of the
identifiable component in the sample analyzed. If between the concentration of the component
in the sample and the measured signal intensity there is an exact mathematical relationship (in
the simplest case, proportionality), then such a method is called absolute. Absolute methods
include, for example, gravimetry, titrimetry, coulometry. In gravimetry, the content of a
component in a sample is deduced from the mass for a particular compound composition in
which the ingredient is extracted from the sample. For example, the amount of sulphate ions
present in the solution can be identified by precipitating them in the form of BaSO4,
separating, evaporating and weighing the precipitate. The amount of sulphate ions in the
analyzed solution can be calculated from the numerical value of the mass of the sediment. In
titrimetry, the amount of the ingredient to be determined is deduced from the appropriate
precise concentration of the volume of solution used in the reaction with this ingredient. The
quantity of component to be determined in the coulometric sample is calculated from the
amount of current consumed to reduce or oxidize this component to the corresponding
Many dozens of other methods of quantitative analysis belong to relative methods, which
do not have simple easy-to-understand explanations of the relationship between the quantity
of the ingredient to be detected and the intensity of the analytical signal. In these methods,
each analyst must experimentally identify this relationship, which is usually depicted as the
calibration graph of the respective hardware. The amount (concentration) of the detectable
component corresponding to the numerical value of the analytical sample measured in the
same conditions is then found from the graph.
1.11.Certified standard materials
Certified Reference Materials (CRMs) are ‘controls’ or standards used to check the
quality and metrological traceability of products, to validate analytical measurement methods,
or for the calibration of instruments. A certified reference material is a particular form
of measurement standard.
Reference materials are particularly important for analytical chemistry and clinical
analysis. Since most analytical instrumentation is comparative, it requires a sample of known
composition (reference material) for accurate calibration. These reference materials are
produced under stringent manufacturing procedures and differ from laboratory reagents in
their certification and the traceability of the data provided.
Standard or pure substances are chemically pure, individual substances of a
Standard or reference samples are composite samples (metal alloys, ores, minerals,
etc.) containing various concentrations of the components of interest, and these concentrations
are precisely determined by suitable absolute methods. A set of standard samples must be
used which, after qualitative and quantitative composition, is close to the sample to be
analyzed. The graduation graphs, obtained with reference samples, provide more accurate
analytical results becausethey exclude or at least reduce the other components effecton the
intensity of the analytical signal. Standard samples are much more expensive compared to
standard substances, since their homogenisation and very careful determination of the
composition is labor-intensive.
1.12. Unification and standardization of analytical methods. Reference methods
Several methods have been developed and suggested to identify the individual
components of different objects. However, none of these methods is ideal and the results
obtained with them include greater or lesser mistakes – results obtained can be either lowered
or higher than the true value. In order to avoid potential differences between the material
suppliers and the beneficiaries due to different analytical results, if different methods are used,
in the sectors of production, nationally or transnationally one (sometimes two) sufficiently
convenient and precise method (unification of method) is selected. This method then, after
appropriate agreement with the National Standards Committee, will be used as a
mandatory(obligatory) reference method in the future.
1.13. Analytical control of scientific research and production processes. Tasks
and structure of analytical services
In the production of various industries the composition of raw materials and finished
products is under control. In order to avoid deflection of production, analytical methods also
are required to control the technological processes, either periodically or preferably
continuously. Many other areas of human work (health care, meteorological, agrochemical,
geological services, etc.) also require information about chemical composition of the relevant
The synthesis of new substances and the detection of their composition and properties,
as well as the development of new or improved existing technological processes, also require
the results of chemical analysis. For this purpose, scientific research institutions, factories,
clinics, etc. institutions are creating analytical laboratories, which carry out many analyzes on
a daily basis. Research and scientific institutes, central laboratories of large factories usually
develop new quality control methods for production, which are then usually standardized. The
factory central laboratories also carry out quality control of raw materials and finished
products. In turn, the factories in the workshop laboratories control the technological process
with the fastest possible methods, unless an automatic control of the production process is
The methods involved in the production process are divided into marking, express and
Marking methods include those that control the quality of raw materials and finished
products. Their labor intensity is not very limited, but they must be very precise, because the
results of these analyzes give the product the appropriate quality.
For the control of the production process, express analysis methods are used, the
accuracy of which may not be so high, but they must be as fast as possible in order to timely
adjust the technological process and prevent the production of defective products.
If there is a dispute between the supplier and receiver on the quality of the raw
material or product, an analysis of the arbitrage is carried out. It is usually carried out with the
same marking analysis methods very carefully, but is is done by some third, uninterested
organization with highly qualified, experienced analysts.
1.14. Development trends of chemical analysis methods
New methods of analysis are designed to have better metrological parameters than
selective methods compared with existing methods - selectivity, low concentration, accuracy
and speed. The time needed to perform the analysis can be greatly shortened by automating
the process of obtaining the analytical signal itself and evaluating this signal and its intensity
with the computer. With automatic analyzers, the analysis can be obtained within minutes or
even seconds. This opens up a wide range of possibilities to fully automate the production
processes, as well as continuously control the purity of the environment (air, water). For this
purpose, it is necessary to find specific and highly sensitive sensors, including reactive
electrodes, for detecting and quantifying the various components in the subject being
analyzed. The optical and electrochemical analysis methods are the easiest to automate.
New, convenient methods should be developed for the detection of various harmful
substances, including organic compounds, such as dioxins, in water, soil, plants and ready-to-
eat foodstuffs, to which until now their identification was not relevant.
Various new products are still being created, for which quality control requires the
development of appropriate analytical methods.
It is very important to improve the existing and develop new microanalysis methods,
as well as methods for analyzing in distance (for example, the study of the composition of