H1_4.ai

Talk Letter
Vol.2 February 2009 Shimadzu Atomic Absorption Spectrophotometers Reaching even greater heights Unprecedented sensitivity, thanks to a newly developed 3D optical system Advanced safety technology System configuration evolving to suit the needs of the user The newly developed 3D optical system is capable of flame: Pb 0.015 ppm detection, and furnace: Pb 0.00005 ppm detection.
Equipped with the world's first*1 vibration sensor, a multimode automatic gas leak check function, and other advanced safety technology.
Evolving from the basic flame model to suit the needs of the user. The dual atomizer system*2 is the world's smallest*1, and a furnace model is also available.
Easy-to-understand, user-friendly WizAArd software supports FDA 21 CFR Part 11 compliance.
*1 Survey by Shimadzu in November 2008.
*2 The optional auto atomizer changer is required.
Founded in 1875, Shimadzu Corporation, a leader in the development of advanced technologies, has a distinguished history of innovation built on the foundation of contributing to society through science and technology. We maintain a global network of sales, service, technical support and applications centers on six continents, and have established long-term relationships with a host of highly trained distributors located
in over 100 countries. For information about Shimadzu, and to
contact your local office, please visit our Web site at
www.shimadzu.com
SHIMADZU CORPORATION. International Marketing Division
3. Kanda-Nishikicho 1-chome, Chiyoda-ku, Tokyo 101-8448, Japan
Phone: 81(3)3219-5641 Fax. 81(3)3219-5710
URL http://www.shimadzu.com
The contents of this brochure are subject to change without notice.
Printed in Japan 3295-11802-30ANS (1) Halogen Lamp
The principle for light emission is the same as that for a standard incandescent bulb. Electric current is supplied to a filament, the filament becomes hot, and light is emitted. The bulb in a halogen lamp is filled with inert gas and a small amount of a halogen. While the tungsten used as the alk Letter
filament evaporates due to the high temperature, the halide causes the tungsten to return to the filament. This helps create a bright light source with a long service life. The emission intensity distribution of a halogen lamp can UV Talk Letter
be approximated using Planck's law of radiation. Fig. 4 shows the emission February 2009 intensity distribution for a temperature of 3,000 K. A halogen lamp offers Relative intensity 0.2 The Structure of a Spectrophotometer superior temporal stability, a service life of approx. 2,000 hours, and a relatively low cost. It has relatively high levels of each of the properties a) to d) mentioned above.
1.The Measurement Principle Used by a Spectrophotometer (2) Deuterium Lamp
A deuterium lamp is a discharge light source in which the bulb is filled with
Fig.4 Emission Intensity Distribution of Halogen Lamp (3,000K) The basic measurement principle used by a spectrophotometer is relatively deuterium (D2) at a pressure of several hundred pascals. Fig. 5 shows the simple and easy to understand. I will explain the principle as it applies to emission intensity distribution for a deuterium lamp. Although 400 nm is, in solid samples and solution samples separately.
general, an approximate usage limit at the long wavelength end, because the (1) Solid Samples
degree of attenuation at this end is quite low, light of wavelengths greater As shown in Fig. 1, first the intensity of the measurement light beam, I0, is than 400 nm is used. In the region beyond 400 nm, there are also large measured without the sample set. Then the sample is set in the path of the (protruding window: 1 mm thick) (protruding window: 1 mm thick) (protruding window: 1 mm thick) numbers of bright line spectra. Among these, the bright line spectra at measurement light beam, and the intensity of the light beam after it passes 486.0 nm and 656.1 nm are particularly intense, and can be used for the through the sample, It, is measured.
wavelength calibration of spectrophotometers. The usage limit at the short wavelength end is determined by the transmittance of the window material. In The product of the transmittance, T, and 100 is the percent transmittance (%T).
Fig. 5, the graphs for cases where synthetic silica and UV glass are used for the window material are given as examples.
(2) Solution Samples
As shown in Fig. 2, a cell containing solvent is set in the path of the
measurement light beam, and the intensity of the light beam after it passes through the cell, I0, is measured. Next, a cell containing a solution produced Spectroscopy is the technique of splitting light that consists of various by dissolving the sample in the solvent is set in the path of the measurement wavelengths into components that correspond to those wavelengths. The light beam, and the intensity of the light beam after it passes through the cell, element that splits this light is called a dispersive element. Prisms and Radiation intensity ( It, is measured. The transmittance, T, is given by equation (1), but with diffraction gratings are typical dispersive elements. Prisms used to be solution samples, it is more common to use the absorbance, Abs, which is commonly used as the dispersive elements in spectrometers, but recently, Fig.5 Emission Intensity Distribution of Deuterium Lamp1) given by equation (2).
diffraction gratings have become the most commonly used type of dispersive element. The diffraction gratings used in spectrophotometers have from Equation (3), which expresses the relationship between the absorbance, Abs, several hundred to approximately 2,000 parallel grooves per millimeter cut and the sample concentration, C, is called the "Lambert-Beer law". There is a into them at equal intervals. An example of a cross-section is shown in Fig. 6. proportional relationship between the absorbance and concentration, and If this diffraction grating is exposed to white light, because of interference, Fig.1 Measurement Principle for Solid Samples this forms the basis of quantitative analysis.
the white light is dispersed in a direction perpendicular to the grooves, and light components of specific wavelengths are reflected only in specific Here, ε is the sample's absorption coefficient and L is the cell's optical path length.
directions. This is illustrated in Fig. 7. λ1 to λ3 represent wavelengths. The Fig.6 Cross Section of Diffraction Grating The measurement method shown in Fig. 2 eliminates the influence of wavelengths change continuously and so if a diffraction grating is exposed to reflection from the cell surface and absorption by the solvent, and ensures white light, it appears iridescent. The way that the clear side of a CD appears that only the absorption due to the sample is measured.
to glitter with iridescence when it is exposed to light is based on the same mechanism as the spectroscopy performed with a diffraction grating.
Monochromatic light is usually used for the measurement light beam shown in Fig. 1 and Fig. 2. Monochromatic light is light that consists of a single A monochrometer consists of an entrance slit, an exit slit, and a diffraction wavelength. To be precise, it has a spectral bandwidth (slit width). For grating, as well as the mirrors and other parts that come with them. Although Cell containing solvent example, monochromatic light with a wavelength of 500 nm and a spectral various types of monochrometers, which vary according to the arrangement bandwidth of 2 nm is light that covers a wavelength interval (full width at half of the elements, have been devised, Fig. 8 shows an example of the simplest maximum) spanning 499 and 501 nm.
monochrometer configuration, which uses a concave diffraction grating. Light of varying wavelengths is projected from the output slit by rotating the 2.The Configuration of a Spectrophotometer concave diffraction grating.
You will find from the above explanation that the indispensable elements of a 5.Sample Compartment spectrophotometer consist, as shown in Fig. 3, of a light source, a Diffraction grating spectrometer, a sample compartment, and a detector. Although I said in the Fig. 9 shows an example of a standard sample compartment. You can see previous section that the sample is exposed to monochromatic light, there that two light beams (indicated by red arrows in Fig. 9) pass through the are instruments in which white light is passed through the sample before compartment, and that this is therefore the sample compartment of a Fig.7 Dispersion of Light by Diffraction Grating being passed into the spectrometer. This method is employed in high-speed "double-beam spectrophotometer". The monochromatic light that leaves the photometry instruments that use array detectors.
spectrometer is split into two beams before it enters the sample In the next sections, I will give an explanation of each element.
compartment. A spectrophotometer in which only one beam passes through Cell containing sample solution the sample compartment is called a "single-beam spectrophotometer". An explanation of the difference between single-beam and double-beam Fig.2 Measurement Principle for Solution Samples spectrophotometers is given in the Q&A of previous issue of UV Talk Letter. The desirable properties of a light source are as follows: Refer to this explanation if necessary.
a) Brightness across a wide wavelength rangeb) Stability over time In a standard configuration, the sample compartment contains cell holders c) A long service life that, as shown in Fig. 9, hold square cells with optical path lengths of 10 mm. The various accessories are attached by replacing these cell holder units or Although there are no light sources that have all of these properties, the most by replacing the entire sample compartment. Among spectrophotometers of Concave diffraction commonly used light sources at the moment are the halogen lamps used for medium or higher grade that use photomultipliers, which will be described the visible and near-infrared regions and the deuterium lamps used for the later, as detectors, there are models for which large sample compartments ultraviolet region. Apart from these, xenon flash lamps are sometimes used.
are made available in order to allow the analysis of large samples or the attachment of large accessories.
Fig.8 Graphic Illustration of a Concave-Grating Spectrometer Fig.3 Configuration of Spectrophotometer (1) Halogen Lamp
The principle for light emission is the same as that for a standard incandescent bulb. Electric current is supplied to a filament, the filament becomes hot, and light is emitted. The bulb in a halogen lamp is filled with inert gas and a small amount of a halogen. While the tungsten used as the alk Letter
filament evaporates due to the high temperature, the halide causes the tungsten to return to the filament. This helps create a bright light source with a long service life. The emission intensity distribution of a halogen lamp can UV Talk Letter
be approximated using Planck's law of radiation. Fig. 4 shows the emission February 2009 intensity distribution for a temperature of 3,000 K. A halogen lamp offers Relative intensity 0.2 The Structure of a Spectrophotometer superior temporal stability, a service life of approx. 2,000 hours, and a relatively low cost. It has relatively high levels of each of the properties a) to d) mentioned above.
1.The Measurement Principle Used by a Spectrophotometer (2) Deuterium Lamp
A deuterium lamp is a discharge light source in which the bulb is filled with
Fig.4 Emission Intensity Distribution of Halogen Lamp (3,000K) The basic measurement principle used by a spectrophotometer is relatively deuterium (D2) at a pressure of several hundred pascals. Fig. 5 shows the simple and easy to understand. I will explain the principle as it applies to emission intensity distribution for a deuterium lamp. Although 400 nm is, in solid samples and solution samples separately.
general, an approximate usage limit at the long wavelength end, because the (1) Solid Samples
degree of attenuation at this end is quite low, light of wavelengths greater As shown in Fig. 1, first the intensity of the measurement light beam, I0, is than 400 nm is used. In the region beyond 400 nm, there are also large measured without the sample set. Then the sample is set in the path of the (protruding window: 1 mm thick) (protruding window: 1 mm thick) (protruding window: 1 mm thick) numbers of bright line spectra. Among these, the bright line spectra at measurement light beam, and the intensity of the light beam after it passes 486.0 nm and 656.1 nm are particularly intense, and can be used for the through the sample, It, is measured.
wavelength calibration of spectrophotometers. The usage limit at the short wavelength end is determined by the transmittance of the window material. In The product of the transmittance, T, and 100 is the percent transmittance (%T).
Fig. 5, the graphs for cases where synthetic silica and UV glass are used for the window material are given as examples.
(2) Solution Samples
As shown in Fig. 2, a cell containing solvent is set in the path of the
measurement light beam, and the intensity of the light beam after it passes through the cell, I0, is measured. Next, a cell containing a solution produced Spectroscopy is the technique of splitting light that consists of various by dissolving the sample in the solvent is set in the path of the measurement wavelengths into components that correspond to those wavelengths. The light beam, and the intensity of the light beam after it passes through the cell, element that splits this light is called a dispersive element. Prisms and Radiation intensity ( It, is measured. The transmittance, T, is given by equation (1), but with diffraction gratings are typical dispersive elements. Prisms used to be solution samples, it is more common to use the absorbance, Abs, which is commonly used as the dispersive elements in spectrometers, but recently, Fig.5 Emission Intensity Distribution of Deuterium Lamp1) given by equation (2).
diffraction gratings have become the most commonly used type of dispersive element. The diffraction gratings used in spectrophotometers have from Equation (3), which expresses the relationship between the absorbance, Abs, several hundred to approximately 2,000 parallel grooves per millimeter cut and the sample concentration, C, is called the "Lambert-Beer law". There is a into them at equal intervals. An example of a cross-section is shown in Fig. 6. proportional relationship between the absorbance and concentration, and If this diffraction grating is exposed to white light, because of interference, Fig.1 Measurement Principle for Solid Samples this forms the basis of quantitative analysis.
the white light is dispersed in a direction perpendicular to the grooves, and light components of specific wavelengths are reflected only in specific Here, ε is the sample's absorption coefficient and L is the cell's optical path length.
directions. This is illustrated in Fig. 7. λ1 to λ3 represent wavelengths. The Fig.6 Cross Section of Diffraction Grating The measurement method shown in Fig. 2 eliminates the influence of wavelengths change continuously and so if a diffraction grating is exposed to reflection from the cell surface and absorption by the solvent, and ensures white light, it appears iridescent. The way that the clear side of a CD appears that only the absorption due to the sample is measured.
to glitter with iridescence when it is exposed to light is based on the same mechanism as the spectroscopy performed with a diffraction grating.
Monochromatic light is usually used for the measurement light beam shown in Fig. 1 and Fig. 2. Monochromatic light is light that consists of a single A monochrometer consists of an entrance slit, an exit slit, and a diffraction wavelength. To be precise, it has a spectral bandwidth (slit width). For grating, as well as the mirrors and other parts that come with them. Although Cell containing solvent example, monochromatic light with a wavelength of 500 nm and a spectral various types of monochrometers, which vary according to the arrangement bandwidth of 2 nm is light that covers a wavelength interval (full width at half of the elements, have been devised, Fig. 8 shows an example of the simplest maximum) spanning 499 and 501 nm.
monochrometer configuration, which uses a concave diffraction grating. Light of varying wavelengths is projected from the output slit by rotating the 2.The Configuration of a Spectrophotometer concave diffraction grating.
You will find from the above explanation that the indispensable elements of a 5.Sample Compartment spectrophotometer consist, as shown in Fig. 3, of a light source, a Diffraction grating spectrometer, a sample compartment, and a detector. Although I said in the Fig. 9 shows an example of a standard sample compartment. You can see previous section that the sample is exposed to monochromatic light, there that two light beams (indicated by red arrows in Fig. 9) pass through the are instruments in which white light is passed through the sample before compartment, and that this is therefore the sample compartment of a Fig.7 Dispersion of Light by Diffraction Grating being passed into the spectrometer. This method is employed in high-speed "double-beam spectrophotometer". The monochromatic light that leaves the photometry instruments that use array detectors.
spectrometer is split into two beams before it enters the sample In the next sections, I will give an explanation of each element.
compartment. A spectrophotometer in which only one beam passes through Cell containing sample solution the sample compartment is called a "single-beam spectrophotometer". An explanation of the difference between single-beam and double-beam Fig.2 Measurement Principle for Solution Samples spectrophotometers is given in the Q&A of previous issue of UV Talk Letter. The desirable properties of a light source are as follows: Refer to this explanation if necessary.
a) Brightness across a wide wavelength rangeb) Stability over time In a standard configuration, the sample compartment contains cell holders c) A long service life that, as shown in Fig. 9, hold square cells with optical path lengths of 10 mm. The various accessories are attached by replacing these cell holder units or Although there are no light sources that have all of these properties, the most by replacing the entire sample compartment. Among spectrophotometers of Concave diffraction commonly used light sources at the moment are the halogen lamps used for medium or higher grade that use photomultipliers, which will be described the visible and near-infrared regions and the deuterium lamps used for the later, as detectors, there are models for which large sample compartments ultraviolet region. Apart from these, xenon flash lamps are sometimes used.
are made available in order to allow the analysis of large samples or the attachment of large accessories.
Fig.8 Graphic Illustration of a Concave-Grating Spectrometer Fig.3 Configuration of Spectrophotometer The Structure of a Spectrophotometer Applications The Relationship Between UV-VIS Absorption and Structure of Organic Compounds The Relationship Between UV-VIS Absorption and Structure of Organic Compounds There are many colored organic compounds, such as dyes and pigments. How is it that these colors come about? The light beams that pass through the sample compartment enter the detector, which is the last element in the spectrophotometer. Photomultipliers There is a close relationship between the color of an organic compound and its structure. Here, I will explain this and silicon photodiodes are typical detectors used with spectrophotometers relationship using absorption spectra of organic compounds obtained with Shimadzu's UV-2550 UV-VIS for the ultraviolet and visible regions. For the near-infrared region, PbS photoconductive elements have always been used in the past, but recently, instruments incorporating InGaAs photodiodes have been sold. Silicon photodiode array detectors are used, in combination with the back spectroscopy method, for high-speed photometry instruments.
1.The Relationship Between Conjugated Double Photomultipliers and silicon photodiodes are described below.
Bond Systems and Absorption Peaks Measurement-side A photomultiplier is a detector that uses the fact that photoelectrons are There are many organic compounds that have conjugated discharged from a photoelectric surface when it is subjected to light (i.e., the double bond systems (hereafter referred to as "conjugated external photoelectric effect). The photoelectrons emitted from the systems"), in which every other bond is a double bond. These photoelectric surface repeatedly cause secondary electron emission in sequentially arranged dynodes, ultimately producing a large output for a conjugated systems have a large influence on peak Fig.1 Structures of Benzene, Naphthalene, and Anthracene relatively small light intensity. The most important feature of a photomultiplier wavelengths and absorption intensities.
is that it achieves a significantly high level of sensitivity that cannot be Fig.9 Sample Compartment Fig. 1 shows the structures of benzene, naphthalene, and obtained with other optical sensors. If there is sufficient light intensity, this feature is not particularly relevant, but as the light intensity decreases, this anthracene. Fig. 2 shows the absorption spectra obtained by feature becomes increasingly useful. For this reason, photomultipliers are dissolving these compounds in ethanol and analyzing the used in high-grade instruments. The spectral sensitivity characteristics of a resulting solutions. The concentrations were adjusted so that photomultiplier are mainly determined by the material of the photoelectric surface. Fig. 10 shows an example of the spectral sensitivity characteristics the absorption intensities of the components were roughly the of a multi-alkali photoelectric surface, a type of surface that is often used in same. It can be seen in Fig. 2 that peak wavelengths tend to be shifted toward the long wavelength region as the (2) Silicon Photodiode
conjugated system gets larger. Table 11) gives the peak A silicon photodiode is a detector that uses the fact that the electrical wavelengths and the molar absorption coefficients of various properties of a detector change when it is exposed to light (i.e., the internal organic compounds. The molar absorption coefficient is a photoelectric effect). Solar cells, which have attracted much attention recently, use the same structure and principle as silicon photodiodes. In measurement of how strongly a substance absorbs light. The comparison with photomultipliers, silicon photodiodes offer advantages such larger its value, the greater the absorption. With larger as low cost, little locality of sensitivity in the light-receiving surface, and the conjugated systems, the absorption peak wavelengths tend to Fig.2 Absorption Spectra of Benzene, Naphthalene, and Anthracene fact that a special power supply is not required. Even regarding sensitivity, if the light intensity is relatively large, they can obtain photometric data that is be shifted toward the long wavelength region and the Molar Absorption Coefficient no inferior to that obtained with photomultipliers. Fig. 11 shows an example of absorption peaks tend to be larger.
the spectral sensitivity characteristics of a silicon photodiode.
Ethylene (CH2=CH2) 2.Absorption Spectra of Food Dyes with Large Conjugated Systems Here, I have given an overview of the structure of UV-VIS Fig. 3 shows the structures of food dyes New Coccine (Red spectrophotometers. Due to space limitations, I have only described the Radiation sensitivity of photoelectric surface (mA/W) No. 102) and Brilliant Blue FCF (Blue No. 1) and Fig. 4 shows basics. In the future, I plan to give more detailed explanations about their absorption spectra. Food dyes tend to have large specialized topics. I look forward to your continued interest.
Table 1 Absorption Peaks and Molar Absorption Coefficients of Various Organic Substances1) conjugated systems, like those shown in Fig. 3, and therefore their peak wavelengths tend to be shifted toward the long Fig.10 Spectral Sensitivity Characteristics of a Photomultiplier2) wavelength region, with peaks appearing in the visible region 1) Hamamatsu Photonics Deuterium Lamp Brochure (400 to 700 nm). This is why they are recognized as colors.
2) Hamamatsu Photonics Photomultiplier Brochure 3) Hamamatsu Photonics Photodiode Brochure Incidentally, the color that we see is the color that is not absorbed by the substance (which is called the "complementary color"). As shown in Fig. 4, New Coccine absorbs blue and green light in the range 450 to 550 nm, and Brilliant Blue FCF so the complementary color, red, is seen by the human eye. Fig.3 Structures of New Coccine and Brilliant Blue FCF Brilliant Blue FCF absorbs yellow light in the range 560 to 650 nm and so blue is seen by the human eye.
Brilliant blue FCF Light-receiving sensitivity (A/W) Fig.11 Spectral Sensitivity Characteristics of a Silicon Photodiode3) Tatsumi Sato (Ph, D,) Spectroscopy Business Unit, Analytical & Measuring Instruments Division Fig.4 Absorption Spectra of Food Dyes New Coccine and Brilliant Blue FCF The Structure of a Spectrophotometer Applications The Relationship Between UV-VIS Absorption and Structure of Organic Compounds The Relationship Between UV-VIS Absorption and Structure of Organic Compounds There are many colored organic compounds, such as dyes and pigments. How is it that these colors come about? The light beams that pass through the sample compartment enter the detector, which is the last element in the spectrophotometer. Photomultipliers There is a close relationship between the color of an organic compound and its structure. Here, I will explain this and silicon photodiodes are typical detectors used with spectrophotometers relationship using absorption spectra of organic compounds obtained with Shimadzu's UV-2550 UV-VIS for the ultraviolet and visible regions. For the near-infrared region, PbS photoconductive elements have always been used in the past, but recently, instruments incorporating InGaAs photodiodes have been sold. Silicon photodiode array detectors are used, in combination with the back spectroscopy method, for high-speed photometry instruments.
1.The Relationship Between Conjugated Double Photomultipliers and silicon photodiodes are described below.
Bond Systems and Absorption Peaks Measurement-side A photomultiplier is a detector that uses the fact that photoelectrons are There are many organic compounds that have conjugated discharged from a photoelectric surface when it is subjected to light (i.e., the double bond systems (hereafter referred to as "conjugated external photoelectric effect). The photoelectrons emitted from the systems"), in which every other bond is a double bond. These photoelectric surface repeatedly cause secondary electron emission in sequentially arranged dynodes, ultimately producing a large output for a conjugated systems have a large influence on peak Fig.1 Structures of Benzene, Naphthalene, and Anthracene relatively small light intensity. The most important feature of a photomultiplier wavelengths and absorption intensities.
is that it achieves a significantly high level of sensitivity that cannot be Fig.9 Sample Compartment Fig. 1 shows the structures of benzene, naphthalene, and obtained with other optical sensors. If there is sufficient light intensity, this feature is not particularly relevant, but as the light intensity decreases, this anthracene. Fig. 2 shows the absorption spectra obtained by feature becomes increasingly useful. For this reason, photomultipliers are dissolving these compounds in ethanol and analyzing the used in high-grade instruments. The spectral sensitivity characteristics of a resulting solutions. The concentrations were adjusted so that photomultiplier are mainly determined by the material of the photoelectric surface. Fig. 10 shows an example of the spectral sensitivity characteristics the absorption intensities of the components were roughly the of a multi-alkali photoelectric surface, a type of surface that is often used in same. It can be seen in Fig. 2 that peak wavelengths tend to be shifted toward the long wavelength region as the (2) Silicon Photodiode
conjugated system gets larger. Table 11) gives the peak A silicon photodiode is a detector that uses the fact that the electrical wavelengths and the molar absorption coefficients of various properties of a detector change when it is exposed to light (i.e., the internal organic compounds. The molar absorption coefficient is a photoelectric effect). Solar cells, which have attracted much attention recently, use the same structure and principle as silicon photodiodes. In measurement of how strongly a substance absorbs light. The comparison with photomultipliers, silicon photodiodes offer advantages such larger its value, the greater the absorption. With larger as low cost, little locality of sensitivity in the light-receiving surface, and the conjugated systems, the absorption peak wavelengths tend to Fig.2 Absorption Spectra of Benzene, Naphthalene, and Anthracene fact that a special power supply is not required. Even regarding sensitivity, if the light intensity is relatively large, they can obtain photometric data that is be shifted toward the long wavelength region and the Molar Absorption Coefficient no inferior to that obtained with photomultipliers. Fig. 11 shows an example of absorption peaks tend to be larger.
the spectral sensitivity characteristics of a silicon photodiode.
Ethylene (CH2=CH2) 2.Absorption Spectra of Food Dyes with Large Conjugated Systems Here, I have given an overview of the structure of UV-VIS Fig. 3 shows the structures of food dyes New Coccine (Red spectrophotometers. Due to space limitations, I have only described the Radiation sensitivity of photoelectric surface (mA/W) No. 102) and Brilliant Blue FCF (Blue No. 1) and Fig. 4 shows basics. In the future, I plan to give more detailed explanations about their absorption spectra. Food dyes tend to have large specialized topics. I look forward to your continued interest.
Table 1 Absorption Peaks and Molar Absorption Coefficients of Various Organic Substances1) conjugated systems, like those shown in Fig. 3, and therefore their peak wavelengths tend to be shifted toward the long Fig.10 Spectral Sensitivity Characteristics of a Photomultiplier2) wavelength region, with peaks appearing in the visible region 1) Hamamatsu Photonics Deuterium Lamp Brochure (400 to 700 nm). This is why they are recognized as colors.
2) Hamamatsu Photonics Photomultiplier Brochure 3) Hamamatsu Photonics Photodiode Brochure Incidentally, the color that we see is the color that is not absorbed by the substance (which is called the "complementary color"). As shown in Fig. 4, New Coccine absorbs blue and green light in the range 450 to 550 nm, and Brilliant Blue FCF so the complementary color, red, is seen by the human eye. Fig.3 Structures of New Coccine and Brilliant Blue FCF Brilliant Blue FCF absorbs yellow light in the range 560 to 650 nm and so blue is seen by the human eye.
Brilliant blue FCF Light-receiving sensitivity (A/W) Fig.11 Spectral Sensitivity Characteristics of a Silicon Photodiode3) Tatsumi Sato (Ph, D,) Spectroscopy Business Unit, Analytical & Measuring Instruments Division Fig.4 Absorption Spectra of Food Dyes New Coccine and Brilliant Blue FCF Application The Relationship Between UV-VIS Absorption and Structure of Organic Compounds Q&A What Is Stray Light? 3.The Influence of Functional Groups Absorption peaks are also influenced by functional groups. The term "stray light" appears in
Fig. 5 shows the absorption spectra of benzene, phenol, which consists of a hydroxyl group bonded to a benzene ring, and p- product brochures. What is this exactly?
nitrophenol, which consists of a hydroxyl group and a nitro group bonded to a benzene ring. The functional groups influence the conjugated systems, causing the absorption Red: p-Nitrophenol peaks to appear at longer wavelengths than the peak wavelength of benzene, although they do not go beyond 400 nm and enter the visible region. The color of organic compounds, then, is influenced more strongly by the size of the conjugated system.
"Stray light" is light of any wavelength contained in the light used in a spectrophotometer 4.Absorption Spectra of Compounds with a Large Fig.5 Absorption Spectra of Benzene, Phenol, and p-Nitrophenol that differs from the set target wavelength. It is expressed as the ratio (%) of the total Molecular Framework and a Small Conjugated System amount of light of wavelengths other than the target wavelength to the amount of light of Fig. 7 shows the absorption spectra of prednisolone, which is used as a pharmaceutical, and benzene. Although A the target wavelength. Fig.1 shows the graphic illustration of stray light. In Fig. 1, the blue
prednisolone has a large molecular framework, its conjugated section corresponds to the target wavelength and the gray section corresponds to stray system is small and so its peak wavelengths are not shifted light. Checks for stray light are performed using filters (e.g., NaI solution filter and NaNO3 greatly toward the long wavelength region, and its peaks solution filter) that do not allow light of specific wavelengths to pass through. The appear at roughly the same position as those of benzene.
measurement wavelength is set to the wavelength that should be completely absorbed by 5.The Reason for the Shift Toward the Long the filter, the actual transmittance is measured, and from this the amount of stray light is Wavelength Region I have shown the relationship between molecular structure and Fig.6 Structures of Phenol and p-Nitrophenol Stray light is a problem because it influences the linearity of the calibration curves used absorption spectra. Why, then, does the peak wavelength tend for quantitative analysis. This influence is hardly observed at all in low-absorbance to be shifted toward the long wavelength region as the size of regions, but if there is a lot of stray light in high-absorbance, high-concentration regions, the conjugated system increases? Let us consider the the calibration curve is prone to bend. (See Fig. 2.) The wavelength of stray light differs relationship between the energy of light and the movement of from the target wavelength and so it is not absorbed by the sample. Light of wavelengths other than the target wavelength passes through the sample without being absorbed and Light exhibits properties of both waves and particles so, in accordance with the Lambert-Beer law, the measured absorbance is less than the (photons). The energy of one photon is expressed as hc/λ, Red: Prednisolone true value. Even if the calibration curve is bent, quantitative analysis is still possible using where h is Planck's constant, c is the speed of light, and λ is quadratic expressions. However, because the sizes of changes in absorbance with the wavelength.
respect to the sizes of changes in sample concentration decrease, the quantitative error Absorption in the ultraviolet and visible regions is related to the transition of electrons. "Transition" refers to the switching In general, the level of stray light is lower with double-monochromator instruments than it of an electron from one state of motion to another. The state of is with single-monochromator instruments.
motion of the π electrons in the conjugated system changes Fig.7 Absorption Spectra of Prednisolone and Benzene more easily than that of the σ electrons that form the molecular frameworks. If a photon collides with a π electron, that π electron readily changes to a different state of motion. This is true even if the photon has only a small amount of energy. The π electrons in relatively large conjugated systems are more easily affected by low-energy photons. Transition expresses the way that the energy of photons is absorbed by electrons. If a photon has a relatively small amount of energy, the value of hc/λ for that photon is relatively small, and therefore the value of λ is relatively large. λ is observed as the absorption wavelength and so, if there is a conjugated system, peaks tend to appear in regions where λ is large, i.e., the long Fig.8 Structures of Prednisolone and Benzene wavelength region.
1) Masayoshi Nakahara: Fig.1 Graphic Illustration of Stray Light Fig.2 Change in Calibration Curve due to Stray Light Applications Development Center, Analytical Applications Department, "The Science of Color", Baifukan (2002), p. 108 :Target wavelength :Stray light :Low stray light instrument :High stray light instrument Analytical & Measuring Instruments Division Application The Relationship Between UV-VIS Absorption and Structure of Organic Compounds Q&A What Is Stray Light? 3.The Influence of Functional Groups Absorption peaks are also influenced by functional groups. The term "stray light" appears in
Fig. 5 shows the absorption spectra of benzene, phenol, which consists of a hydroxyl group bonded to a benzene ring, and p- product brochures. What is this exactly?
nitrophenol, which consists of a hydroxyl group and a nitro group bonded to a benzene ring. The functional groups influence the conjugated systems, causing the absorption Red: p-Nitrophenol peaks to appear at longer wavelengths than the peak wavelength of benzene, although they do not go beyond 400 nm and enter the visible region. The color of organic compounds, then, is influenced more strongly by the size of the conjugated system.
"Stray light" is light of any wavelength contained in the light used in a spectrophotometer 4.Absorption Spectra of Compounds with a Large Fig.5 Absorption Spectra of Benzene, Phenol, and p-Nitrophenol that differs from the set target wavelength. It is expressed as the ratio (%) of the total Molecular Framework and a Small Conjugated System amount of light of wavelengths other than the target wavelength to the amount of light of Fig. 7 shows the absorption spectra of prednisolone, which is used as a pharmaceutical, and benzene. Although A the target wavelength. Fig.1 shows the graphic illustration of stray light. In Fig. 1, the blue
prednisolone has a large molecular framework, its conjugated section corresponds to the target wavelength and the gray section corresponds to stray system is small and so its peak wavelengths are not shifted light. Checks for stray light are performed using filters (e.g., NaI solution filter and NaNO3 greatly toward the long wavelength region, and its peaks solution filter) that do not allow light of specific wavelengths to pass through. The appear at roughly the same position as those of benzene.
measurement wavelength is set to the wavelength that should be completely absorbed by 5.The Reason for the Shift Toward the Long the filter, the actual transmittance is measured, and from this the amount of stray light is Wavelength Region I have shown the relationship between molecular structure and Fig.6 Structures of Phenol and p-Nitrophenol Stray light is a problem because it influences the linearity of the calibration curves used absorption spectra. Why, then, does the peak wavelength tend for quantitative analysis. This influence is hardly observed at all in low-absorbance to be shifted toward the long wavelength region as the size of regions, but if there is a lot of stray light in high-absorbance, high-concentration regions, the conjugated system increases? Let us consider the the calibration curve is prone to bend. (See Fig. 2.) The wavelength of stray light differs relationship between the energy of light and the movement of from the target wavelength and so it is not absorbed by the sample. Light of wavelengths other than the target wavelength passes through the sample without being absorbed and Light exhibits properties of both waves and particles so, in accordance with the Lambert-Beer law, the measured absorbance is less than the (photons). The energy of one photon is expressed as hc/λ, Red: Prednisolone true value. Even if the calibration curve is bent, quantitative analysis is still possible using where h is Planck's constant, c is the speed of light, and λ is quadratic expressions. However, because the sizes of changes in absorbance with the wavelength.
respect to the sizes of changes in sample concentration decrease, the quantitative error Absorption in the ultraviolet and visible regions is related to the transition of electrons. "Transition" refers to the switching In general, the level of stray light is lower with double-monochromator instruments than it of an electron from one state of motion to another. The state of is with single-monochromator instruments.
motion of the π electrons in the conjugated system changes Fig.7 Absorption Spectra of Prednisolone and Benzene more easily than that of the σ electrons that form the molecular frameworks. If a photon collides with a π electron, that π electron readily changes to a different state of motion. This is true even if the photon has only a small amount of energy. The π electrons in relatively large conjugated systems are more easily affected by low-energy photons. Transition expresses the way that the energy of photons is absorbed by electrons. If a photon has a relatively small amount of energy, the value of hc/λ for that photon is relatively small, and therefore the value of λ is relatively large. λ is observed as the absorption wavelength and so, if there is a conjugated system, peaks tend to appear in regions where λ is large, i.e., the long Fig.8 Structures of Prednisolone and Benzene wavelength region.
1) Masayoshi Nakahara: Fig.1 Graphic Illustration of Stray Light Fig.2 Change in Calibration Curve due to Stray Light Applications Development Center, Analytical Applications Department, "The Science of Color", Baifukan (2002), p. 108 :Target wavelength :Stray light :Low stray light instrument :High stray light instrument Analytical & Measuring Instruments Division Talk Letter
Vol.2 February 2009 Shimadzu Atomic Absorption Spectrophotometers Reaching even greater heights Unprecedented sensitivity, thanks to a newly developed 3D optical system Advanced safety technology System configuration evolving to suit the needs of the user The newly developed 3D optical system is capable of flame: Pb 0.015 ppm detection, and furnace: Pb 0.00005 ppm detection.
Equipped with the world's first*1 vibration sensor, a multimode automatic gas leak check function, and other advanced safety technology.
Evolving from the basic flame model to suit the needs of the user. The dual atomizer system*2 is the world's smallest*1, and a furnace model is also available.
Easy-to-understand, user-friendly WizAArd software supports FDA 21 CFR Part 11 compliance.
*1 Survey by Shimadzu in November 2008.
*2 The optional auto atomizer changer is required.
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