340
obtained in this way provide very useful information on the structure of the test
compound. For example, it is an indispensable auxiliary (and often the main) method
for identifying natural conjugate compounds (such as plant pigments (carotenoids),
polyacetylenes, porphyrins, total phenols, flavonoids, total anthocyanins, monomeric anthocyanins), percentage of polymer color, total antioxidant activity, etc. In
addition to its application for the identification of organic compounds, UV/Vis spectrophotometry is widely used today in quantitative analysis. Its advantages over
other methods are its extremely high sensitivity and easy operation of the instrument.
Infrared radiation (IR) is electromagnetic radiation of wavelengths from 0.7 to
500 mm. Its name derives from the fact that the energies of infrared radiation are
less than the energies of the visible part of the spectrum to which they continue. The
IR method has many advantages because they allow fast measurement of a large
number of quantities without destroying the sample. Near-infrared radiation affects
the stretching vibrations of covalent bonds C–H, N–H, and O–H in the molecule.
Near-infrared spectroscopy techniques use the near-infrared reflection (NIR) and
near-infrared emission (NIT) techniques. These techniques can be used to analyze
liquids and solids such as milk, cheeses, and milk powder.
Atomic absorption spectrophotometry (AAS) is an absorption method that measures the decrease in the intensity of monochromatic radiation as it passes through
the atomic vapor of a sample. Hollow cathode lamps made of the element to be
determined are used as the radiation source. The samples are evaporated at temperatures from 2000 to 6000 K, and then the absorption of electromagnetic radiation of
the appropriate wavelength is measured. Due to the high sensitivity, it is possible to
determine more elements from the solution even in a very low concentration range.
AAS is primarily used to determine the concentration of metals in foods such as metals in plant material and plant extracts. Samples that are already liquid (e.g., fruit
juices, wine) can be easily analyzed without prior preparation, i.e., after dilution with
water or a reagent. The basic prerequisite for analysis by atomic absorption spectrophotometry is that the sample be homogeneous and at least in a semiliquid state.
Most often, concentrations are determined from a calibration diagram obtained using
a series of standard solutions of the analyzed element of known concentrations.
Newer AASs are equipped with a computer device that easily programs the analysis
parameters and prints the measurement results. The instrument measures each standard, i.e., sample, three times, conducts measurement statistics, constructs a calibration diagram, and calculates the concentration of an unknown sample. Important
advantages of AAS are primarily the analysis of about 65 different elements in a
whole range of different samples; low limits of detection (mg/cm
3
, mg/dm
3
, ng/dm
3
)
and possible analysis of trace metals and small amounts of samples; and high precision and accuracy; if the samples are a solution or fine suspension, the pretreatment
of the samples is practically superfluous, and their direct analysis is possible; AAS is
more sensitive to determinations, e.g., Ca, Mg, Cu, Fe, Zn, Pb, Hg, and Cd in biological material. High sensitivity allows analysis of analyte traces, analysis of small
amounts of material, and dilution of solutions which reduces interference.
Atomic emission spectrophotometry (AЕS) is most commonly used in multielement analysis and quantification. Atoms, especially metals, emit electromagnetic
V. I. Petropulos and B. Balabanova
obtained in this way provide very useful information on the structure of the test
compound. For example, it is an indispensable auxiliary (and often the main) method
for identifying natural conjugate compounds (such as plant pigments (carotenoids),
polyacetylenes, porphyrins, total phenols, flavonoids, total anthocyanins, monomeric anthocyanins), percentage of polymer color, total antioxidant activity, etc. In
addition to its application for the identification of organic compounds, UV/Vis spectrophotometry is widely used today in quantitative analysis. Its advantages over
other methods are its extremely high sensitivity and easy operation of the instrument.
Infrared radiation (IR) is electromagnetic radiation of wavelengths from 0.7 to
500 mm. Its name derives from the fact that the energies of infrared radiation are
less than the energies of the visible part of the spectrum to which they continue. The
IR method has many advantages because they allow fast measurement of a large
number of quantities without destroying the sample. Near-infrared radiation affects
the stretching vibrations of covalent bonds C–H, N–H, and O–H in the molecule.
Near-infrared spectroscopy techniques use the near-infrared reflection (NIR) and
near-infrared emission (NIT) techniques. These techniques can be used to analyze
liquids and solids such as milk, cheeses, and milk powder.
Atomic absorption spectrophotometry (AAS) is an absorption method that measures the decrease in the intensity of monochromatic radiation as it passes through
the atomic vapor of a sample. Hollow cathode lamps made of the element to be
determined are used as the radiation source. The samples are evaporated at temperatures from 2000 to 6000 K, and then the absorption of electromagnetic radiation of
the appropriate wavelength is measured. Due to the high sensitivity, it is possible to
determine more elements from the solution even in a very low concentration range.
AAS is primarily used to determine the concentration of metals in foods such as metals in plant material and plant extracts. Samples that are already liquid (e.g., fruit
juices, wine) can be easily analyzed without prior preparation, i.e., after dilution with
water or a reagent. The basic prerequisite for analysis by atomic absorption spectrophotometry is that the sample be homogeneous and at least in a semiliquid state.
Most often, concentrations are determined from a calibration diagram obtained using
a series of standard solutions of the analyzed element of known concentrations.
Newer AASs are equipped with a computer device that easily programs the analysis
parameters and prints the measurement results. The instrument measures each standard, i.e., sample, three times, conducts measurement statistics, constructs a calibration diagram, and calculates the concentration of an unknown sample. Important
advantages of AAS are primarily the analysis of about 65 different elements in a
whole range of different samples; low limits of detection (mg/cm
3
, mg/dm
3
, ng/dm
3
)
and possible analysis of trace metals and small amounts of samples; and high precision and accuracy; if the samples are a solution or fine suspension, the pretreatment
of the samples is practically superfluous, and their direct analysis is possible; AAS is
more sensitive to determinations, e.g., Ca, Mg, Cu, Fe, Zn, Pb, Hg, and Cd in biological material. High sensitivity allows analysis of analyte traces, analysis of small
amounts of material, and dilution of solutions which reduces interference.
Atomic emission spectrophotometry (AЕS) is most commonly used in multielement analysis and quantification. Atoms, especially metals, emit electromagnetic
V. I. Petropulos and B. Balabanova