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For a general history of titrimetry, see the following sources. Kolthoff, I. M. "Analytical Chemistry in the USA in the First Quarter of This Century," *Anal. Chem.* **1994**, *66*, 241A–249A. Laitinen, H. A.; Ewing, G. W., eds. *A History of Analytical Chemistry*. The Division of Analytical Chemistry of the American C... | {
"Header 1": "9J SUGGESTED READINGS",
"token_count": 569,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
- 1. (a) Willis, C. J. *J. Chem. Educ.* **1981,** *58,* 659–663; (b) Nakagawa, K. *J. Chem. Educ.* **1990,** *67,* 673–676; (c) Gordus, A. A. *J. Chem. Educ.* **1991,** *68,* 759–761; (d) de Levie, R. *J. Electroanal. Chem.* **1992,** *323,* 347–355; (e) de Levie, R. *J. Chem. Educ.* **1993,** *70,* 209–217; (f) Chasto... | {
"Header 1": "**9K REFERENCES**",
"token_count": 1453,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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**B**efore the beginning of the twentieth century most quantitative chemical analyses used gravimetry or titrimetry as the analytical method. With these methods, analysts achieved highly accurate results, but were usually limited to the analysis of major and minor analytes. Other methods developed during this period ex... | {
"Header 1": "Spectroscopic Methods of Analysis",
"token_count": 362,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Electromagnetic radiation, or light, is a form of energy whose behavior is described by the properties of both waves and particles. The optical properties of electromagnetic radiation, such as diffraction, are explained best by describing light as a wave. Many of the interactions between electromagnetic radiation and m... | {
"Header 1": "**10A.1 What Is Electromagnetic Radiation**",
"token_count": 995,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In 1817, Josef Fraunhofer (1787–1826) studied the spectrum of solar radiation, observing a continuous spectrum with numerous dark lines. Fraunhofer labeled the most prominent of the dark lines with letters. In 1859, Gustav Kirchhoff (1824–1887) showed that the "D" line in the solar spectrum was due to the absorption of... | {
"Header 1": "EXAMPLE 10.1",
"token_count": 505,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
What is the energy per photon of the sodium D line ( $\lambda = 589 \text{ nm}$ )?
#### SOLUTION
The energy of the sodium D line is
$$E = \frac{hc}{\lambda} = \frac{(6.626 \times 10^{-34} \text{ J} \cdot \text{s}) (3.00 \times 10^8 \text{ m/s})}{589 \times 10^{-9} \text{ m}} = 3.37 \times 10^{-19} \text{ J}$$
#... | {
"Header 1": "EXAMPLE 10.2",
"token_count": 1208,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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| Region of the<br>Electromagnetic Spectrum | Type of Interaction | Spectroscopic Technique |
|-------------------------------------------|---------------------|--------------------------------|
| X-ray | diffraction | X-ray diffraction |
| UV/Visa ... | {
"Header 1": "**Table 10.2 Representative Spectroscopies That Do Not Involve an Exchange of Energy**",
"token_count": 387,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The instruments used in spectroscopy consist of several common components, including a source of energy that can be input to the sample, a means for isolating a narrow range of wavelengths, a detector for measuring the signal, and a signal processor to display the signal in a form convenient for the analyst. In this se... | {
"Header 1": "**10B Basic Components of Spectroscopic Instrumentation**",
"token_count": 434,
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All forms of spectroscopy require a source of energy. In absorption and scattering spectroscopy this energy is supplied by photons. Emission and luminescence spectroscopy use thermal, radiant (photon), or chemical energy to promote the analyte to a less stable, higher energy state.
**Sources of Electromagnetic Radiat... | {
"Header 1": "**10B.1 Sources of Energy**",
"token_count": 660,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In Nessler's original colorimetric method for ammonia, described at the beginning of the chapter, no attempt was made to narrow the wavelength range of visible light passing through the sample. If more than one component in the sample contributes to the absorption of radiation, however, then a quantitative analysis usi... | {
"Header 1": "**10B.2 Wavelength Selection**",
"token_count": 1589,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The first detector for optical spectroscopy was the human eye, which, of course, is limited both by its accuracy and its limited sensitivity to electromagnetic radiation. Modern detectors use a sensitive **transducer** to convert a signal consisting of photons into an easily measured electrical signal. Ideally the dete... | {
"Header 1": "**10B.3 Detectors**",
"token_count": 902,
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In absorption spectroscopy a beam of electromagnetic radiation passes through a sample. Much of the radiation is transmitted without a loss in intensity. At selected frequencies, however, the radiation's intensity is attenuated. This process of attenuation is called absorption. Two general requirements must be met if a... | {
"Header 1": "**10C.1 Absorbance of Electromagnetic Radiation**",
"token_count": 2042,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Unoccupied, higher energy atomic orbitals also exist. Figure 10.18 shows a partial energy level diagram for sodium's occupied and unoccupied valence shell atomic orbitals. This configuration of atomic orbitals, which shows a splitting of the *p* orbitals into two levels with slightly different energies, may differ from... | {
"Header 1": "**10C.1 Absorbance of Electromagnetic Radiation**",
"token_count": 1907,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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What is the analyte's molar absorptivity at this wavelength?
#### SOLUTION
Solving equation 10.5 for $\varepsilon$ and making appropriate substitutions gives
$$\varepsilon = \frac{A}{bC} = \frac{0.338}{(1.00 \text{ cm})(5.00 \times 10^{-4} \text{ M})} = 676 \text{ cm}^{-1} \text{ M}^{-1}$$
![](_page_400_Figur... | {
"Header 1": "**10C.1 Absorbance of Electromagnetic Radiation**",
"token_count": 1909,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The earliest routine application of molecular absorption spectroscopy, which dates to the 1830s, was colorimetry, in which visible light was absorbed by a sample. The concentration of analyte was determined visually by comparing the sample's color to that of a set of standards using Nessler tubes (as described at the b... | {
"Header 1": "IOD Ultraviolet-Visible and Infrared Spectrophotometry",
"token_count": 2042,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Cells with a longer pathlength are useful for the analysis of very dilute solutions or for gaseous samples. The highest quality cells are constructed in a rectangular shape, allowing the radiation to strike the cell at a 90° angle, where losses to reflection are minimal. These cells, which are usually available in matc... | {
"Header 1": "IOD Ultraviolet-Visible and Infrared Spectrophotometry",
"token_count": 1714,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The determination of an analyte's concentration based on its absorption of ultraviolet or visible radiation is one of the most frequently encountered quantitative analytical methods. One reason for its popularity is that many organic and inorganic compounds have strong absorption bands in the UV/Vis region of the elect... | {
"Header 1": "**10D.2 Quantitative Applications**",
"token_count": 2019,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In many cases the analysis is carried out by collecting the sample in water, converting the analyte to an aqueous form that can be analyzed by methods such as those described in Table 10.6. For example, the concentration of NO2 can be determined by oxidizing NO2 to NO3 –. The concentration of NO3 – is then determined b... | {
"Header 1": "**10D.2 Quantitative Applications**",
"token_count": 243,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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#### Selected Examples of the Application of UV/Vis Molecular Absorption to the Analysis of Clinical Samples
| Analyte | Method | λ<br>(nm) |
|------------... | {
"Header 1": "Table 10.7",
"token_count": 1286,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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*Description of Method.* Iron in the +2 oxidation state reacts with *o*-phenanthroline to form the orange-red Fe(*o*-phen)3 2+ complex (see Figure 10.17). The intensity of the complex's color is independent of solution acidity between a pH of 3 and 9. Due to a faster rate of complex formation in more acidic solutions, ... | {
"Header 1": "**Method 10.1 Determination of Iron in Water and Wastewater11**",
"token_count": 1138,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The determination of Fe in an industrial waste stream was carried out by the *o-*phenanthroline described in Method 10.1. Using the data shown in the following table, determine the concentration of Fe in the waste stream.
| ppm Fe | Absorbance |
|---------|------------|
| 0.00 | 0.000 |
| 1.00 | 0.183 ... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 2020,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Substituting equation 10.15 into 10.11 and 10.12 gives
$$Q_{\lambda_1} = V(A_{\rm m})_{\lambda_1} = (\varepsilon_{\rm X})_{\lambda_1} b n_{\rm X} + (\varepsilon_{\rm Y})_{\lambda_1} b n_{\rm Y}$$
**10.16**
$$Q_{\lambda 2} = V(A_{\rm m})_{\lambda 2} = (\varepsilon_{\rm X})_{\lambda 2} b n_{\rm X} + (\varepsilon_{\rm... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 1914,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Thus, if $(n_{\text{M}})_i$ and $(n_{\text{L}})_i$ are, respectively, the moles of metal and ligand in the i-th solution, then
$$n_{\text{tot}} = (n_{\text{M}})_i + (n_{\text{L}})_i$$
The relative amount of ligand and metal in each solution is expressed as the mole fraction of ligand, $(X_L)_i$ , and the mole ... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 1841,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The concentration of a metal–ligand complex of the general form $M_x L_y$ is
$$[M_x L_y] = \frac{C_L}{v}$$
If absorbance is monitored at a wavelength where only $M_xL_y$ absorbs, then
$$A = \varepsilon b[M_x L_y] = \frac{\varepsilon b C_L}{\gamma}$$
and a plot of absorbance versus $C_L$ will be linear wit... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 2016,
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With appropriate modifications, more-complicated systems, in which one or more of these parameters cannot be measured, also can be treated.<sup>16</sup>
#### 10D.5 Evaluation
**Scale of Operation** Molecular UV/Vis absorption is routinely used for the analysis of trace analytes in macro and meso samples. Major and ... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 2018,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The cost of UV/Vis instrumentation ranges from several hundred dollars for a simple, manually operated, single-beam instrument equipped with an inexpensive grating, to as much as \$50,000 for a computer-controlled, high-resolution, double-beam instrument equipped with variable slits and operating over an extended range... | {
"Header 1": "**EXAMPLE 10.5**",
"token_count": 253,
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Atomic absorption spectrophotometers (Figure 10.37) are designed using either the single-beam or double-beam optics described earlier for molecular absorption spectrophotometers (see Figures 10.25 and 10.26). There are, however, several important differences that are considered in this section.
**Atomization** The mo... | {
"Header 1": "**10E.1 Instrumentation**",
"token_count": 1422,
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#### graphite furnace
An electrothermal atomizer that relies on resistive heating to atomize samples.
**Figure 10.40** Diagram of an electrothermal analyzer.
1–3 cm in length, and 3–8 mm in diameter (Figure 10.40). The graphite tube is housed in an assembly that seals the ends of t... | {
"Header 1": "**Electrothermal Atomizers** A significant improvement in sensitivity is achieved by using resistive heating in place of a flame. A typical electrothermal atomizer, also known as a **graphite furnace**, consists of a cylindrical graphite tube approximately",
"token_count": 621,
"source_pdf": "datas... |
Atomic absorption using either flame or electrothermal atomization is widely used for the analysis of trace metals in a variety of sample matrices. Using the atomic absorption analysis for zinc as an example, procedures have been developed for its determination in samples as diverse as water and wastewater, air, blood,... | {
"Header 1": "**10E.2 Quantitative Applications**",
"token_count": 688,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The concentration of analyte giving an absorbance of 0.00436.
**Figure 10.41**
Schematic diagram of a hollow cathode lamp showing mechanism by which atomic emission is obtained.
#### **Table 10.10 Atomic Absorption Detection Limits for Selected Elements**
#### **Detection Limits (ppb)**
| Element | Flame Atom... | {
"Header 1": "**characteristic concentration**",
"token_count": 2039,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The two most common chemical interferences are the formation of nonvolatile compounds containing the analyte and ionization of the analyte. One example of a chemical interference due to the formation of nonvolatile compounds is observed when PO4 3– or Al3+ is added to solutions of Ca2+. In one study, for example, addin... | {
"Header 1": "**characteristic concentration**",
"token_count": 1085,
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**Description of Method.** Copper and zinc are isolated by digesting tissue samples after extracting any fatty tissue. The concentration of copper and zinc in the supernatant are determined by atomic absorption using an air–acetylene flame.
**Procedure.** Tissue samples are obtained by a muscle needle biopsy and are ... | {
"Header 1": "Method 10.2 Determination of Cu and Zn in Tissue Samples<sup>22</sup>",
"token_count": 887,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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**Scale of Operation** Atomic absorption spectroscopy is ideally suited for the analysis of trace and ultratrace analytes, particularly when using electrothermal atomization. By diluting samples, atomic absorption also can be applied to minor and major analytes. Most analyses use macro or meso samples. The small volume... | {
"Header 1": "**10E.3 Evaluation**",
"token_count": 684,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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An analyte in an excited state possesses an energy, *E*2, that is greater than that when it is in a lower energy state, *E*1. When the analyte returns, or relaxes to a lower energy state the excess energy, ∆*E,*
$$\Delta E = E_2 - E_1$$
must be released. Figure 10.5 shows a simplified picture of this process.
The... | {
"Header 1": "**10F Spectroscopy Based on Emission**",
"token_count": 406,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Photoluminescence is divided into two categories: fluorescence and phosphorescence. Absorption of an ultraviolet or visible photon promotes a valence electron from its ground state to an excited state with conservation of the electron's spin. For example, a pair of electrons occupying the same electronic ground state h... | {
"Header 1": "**10G Molecular Photoluminescence Spectroscopy**",
"token_count": 637,
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To appreciate the origin of molecular fluorescence and phosphorescence, we must consider what happens to a molecule following the absorption of a photon. Let's assume that the molecule initially occupies the lowest vibrational energy level of its electronic ground state. The ground state, which is shown in Figure 10.43... | {
"Header 1": "**10G.1 Molecular Fluorescence and Phosphorescence Spectra**",
"token_count": 2014,
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Figure 10.44 shows the excitation spectrum for the hypothetical system described by the energy level diagram in Figure 10.43. When corrected for variations in source intensity and detector response, a sample's excitation spectrum is nearly identical to its absorbance spectrum. The excitation spectrum provides a conveni... | {
"Header 1": "**10G.1 Molecular Fluorescence and Phosphorescence Spectra**",
"token_count": 1107,
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Molecular fluorescence and, to a lesser extent, phosphorescence have been used for the direct or indirect quantitative analysis of analytes in a variety of matrices. A direct quantitative analysis is feasible when the analyte's quantum yield for fluorescence or phosphorescence is favorable. When the analyte is not fluo... | {
"Header 1": "**10G.3 Quantitative Applications Using Molecular Luminescence**",
"token_count": 564,
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| Chelating Agent | Metal Ions |
|---------------------------------|------------------------------------------|
| 8-hydroxyquinoline | Al3+, Be2+, Zn2+, Li+, Mg2+ (and others) |
| flavonal | Zr2+, Sn4+ |
| be... | {
"Header 1": "**Table 10.12 Selected Chelating Agents for the Fluorometric Analysis of Inorganic Metal Ions**",
"token_count": 816,
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*Description of Method.* Quinine is an alkaloid used in treating malaria (it also is found in tonic water). It is a strongly fluorescent compound in dilute solutions of H2SO4 (Φ<sup>f</sup> = 0.55). The excitation spectrum of quinine shows two absorption bands at 250 nm and 350 nm, and the emission spectrum shows a sin... | {
"Header 1": "**Method 10.3 Determination of Quinine in Urine23**",
"token_count": 975,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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**Scale of Operation** Molecular photoluminescence can be used for the routine analysis of trace and ultratrace analytes in macro and meso samples. Detection limits for fluorescence spectroscopy are strongly influenced by the analyte's quantum yield. For analytes with Φ<sup>f</sup> > 0.5, detection limits in the picomo... | {
"Header 1": "**10G.4 Evaluation**",
"token_count": 798,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In principle, emission spectroscopy can be applied to both atoms and molecules. Molecular infrared emission, or blackbody radiation played an important role in the early development of quantum mechanics and has been used for the analysis of hot gases generated by flames and rocket exhausts. Although the availability of... | {
"Header 1": "**IOH Atomic Emission Spectroscopy**",
"token_count": 663,
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Instrumentation for atomic emission spectroscopy is similar in design to that used for atomic absorption. In fact, most flame atomic absorption spectrometers are easily adapted for use as flame atomic emission spectrometers by turning off the hollow cathode lamp and monitoring the difference between the intensity of ra... | {
"Header 1": "**10H.2 Equipment**",
"token_count": 963,
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Atomic emission is used for the analysis of the same types of samples that may be analyzed by atomic absorption. The development of a quantitative atomic emission method requires several considerations, including choosing a source for atomization and excitation, selecting a wavelength and slit width, preparing the samp... | {
"Header 1": "**10H.3 Quantitative Applications**",
"token_count": 1952,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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*Description of Method.* Salt substitutes, which are used in place of table salt for individuals on a low-sodium diet, contain KCl. Depending on the brand, fumaric acid, calcium hydrogen phosphate, or potassium tartrate also may be present. Typically, the concentration of sodium in a salt substitute is about 100 ppm. T... | {
"Header 1": "**Method 10.4 Determination of Sodium in a Salt Substitute25**",
"token_count": 1521,
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The blue color of the sky during the day and the red color of the sun at sunset result from the scattering of light by small particles of dust, molecules of water, and other gases in the atmosphere. The efficiency with which light is scattered depends on its wavelength. The sky is blue because violet and blue light are... | {
"Header 1": "IO Spectroscopy Based on Scattering",
"token_count": 2045,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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surface-active agent, such as glycerol, gelatin, or dextrin, is added to stabilize the precipitate in a colloidal state and to prevent the coagulation of the particles.
**Applications** Turbidimetry and nephelometry are widely used to determine the clarity of water, beverages, and food products. For example, the tu... | {
"Header 1": "IO Spectroscopy Based on Scattering",
"token_count": 678,
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**Description of Method.** Adding $BaCl_2$ to an acidified sample precipitates $SO_4{}^{2-}$ as $BaSO_4$ . The concentration of $SO_4{}^{2-}$ may be determined either by turbidimetry or nephelometry using an incident source of radiation of 420 nm. External standards containing known concentrations of $SO_4{}^{2... | {
"Header 1": "Method 10.5 Turbidimetric Determination of Sulfate in Water<sup>27</sup>",
"token_count": 877,
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absorbance (*p. 373*) absorbance spectrum (*p. 373*) atomization (*p. 412*) background correction (*p. 419*) Beer's law (*p. 386*) characteristic concentration (*p. 416*) chemiluminescence (*p. 374*) chromophore (*p. 382*) continuum source (*p. 375*) dark current (*p. 379*) effective bandwidth (*p. 376*) electromagneti... | {
"Header 1": "**10J KEY TERMS**",
"token_count": 691,
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Spectroscopic methods of analysis covered in this chapter include those based on the absorption, emission, or scattering of electromagnetic radiation. When a molecule absorbs UV/Vis radiation, it undergoes a change in its valence shell configuration, whereas a change in vibrational energy results for the absorption of ... | {
"Header 1": "**10K SUMMARY**",
"token_count": 529,
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*The following experiments may be used to illustrate the application of spectroscopy to quantitative or characterization problems. Experiments are divided into four groups: those using UV/Vis absorption, those using IR absorption, those using atomic absorption or atomic emission, and tho... | {
"Header 1": "**10L** *Suggested* **EXPERIMENTS**",
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Educ.* **1992**, *69*, 583.
A dye used in the coloration of materials, such as fibers, must be present as the monomer if it is to adsorb to the material's surface. This experiment describes how spectrophotometry can be used to determine the equilibrium constant between a monomer and a dimer for the dye pinacyanol iod... | {
"Header 1": "**10L** *Suggested* **EXPERIMENTS**",
"token_count": 1903,
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**1.** Provide the missing information in the following table
| Wavelength<br>(m) | Frequency<br>(s <sup>-1</sup> ) | Wavenumber<br>(cm <sup>-1</sup> ) | Energy<br>(J/molecule) |
|-----------------------|---------------------------------|-----------------------------------|------------------------|
| $4.50 \times... | {
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"Header 3": "IOM PROBLEMS",
"token_count": 2006,
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A 1.00-mL aliquot of this solution is transferred to a 50-mL volumetric flask, along with 5 mL of thioglycolic acid, 2 mL of 20% w/v ammonium citrate, and 5 mL of 0.22 M NH3 and diluted to volume. The absorbance of this solution is used to determine the concentration of Fe3+ in the sample.
- (a) What is an appropriate ... | {
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"Header 3": "IOM PROBLEMS",
"token_count": 2037,
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For concentrations of methanol between 0 and 30% v/v, the ratio of the absorbance at 663 nm, *A*663, to that at 610 nm, *A*610, is a linear function of the amount of methanol. Using the following standardization data, determine the %v/v methanol in a sample for which *A*<sup>610</sup> is 0.75 and *A*<sup>663</sup> is 1... | {
"Header 1": "**10L** *Suggested* **EXPERIMENTS**",
"Header 3": "IOM PROBLEMS",
"token_count": 1746,
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Results obtained with a PE card are shown below
| g polystyrene | 0.1609 | 0.3290 | 0.4842 | 0.6402 | 0.8006 |
|---------------|--------|--------|--------|--------|--------|
| A1494 cm–1 | 0.0452 | 0.1138 | 0.1820 | 0.3275 | 0.3195 |
| A2064 cm–1 | 0.1948 | 0.2274 | 0.2525 | 0.3580 | 0.2703 |
When a 0.8006-g ... | {
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"Header 3": "IOM PROBLEMS",
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| Wavelength | | | Absorbances | | |
|------------|-------|---------------|---------------|---------|--|
| (nm) | PAR | Cu2+ standard | Zn2+ standard | Mixture | |
| 480 | 0.211 | 0.698 | 0.971 | 0.656 | |
| 496 | 0.137 | 0.732 | 1.018 ... | {
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"Header 3": "IOM PROBLEMS",
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| [TAPP]<br>(M) | –]<br>[NO2<br>(M) | Absorbance |
|---------------|-------------------|------------|
| 8.0 × 10–7 | 1.6 × 10–7 | 0.227 |
| 8.0 × 10–7 | 3.2 × 10–7 | 0.192 |
| 8.0 × 10–7 | 4.8 × 10–7 | 0.158 |
| 8.0 × 10–7 | 8.0 × 10–7 | 0.126 |
| 8.0 × 10–7... | {
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"Header 3": "IOM PROBLEMS",
"token_count": 2047,
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**36.** The concentration of Na in plant materials may be determined by flame atomic emission. The material to be analyzed is prepared by grinding, homogenizing, and drying at 103 °C. A sample of approximately 4 g is transferred to a quartz crucible and heated on a hot plate to char the organic material. The sample i... | {
"Header 1": "**10L** *Suggested* **EXPERIMENTS**",
"Header 3": "IOM PROBLEMS",
"token_count": 2013,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Given the following results, what is the concentration of Se(IV) in the sample?
| Concentration of<br>Se(IV) Added<br>(nM) | Fluorescence<br>Intensity |
|------------------------------------------|---------------------------|
| 0 | 323 |
| 2.00 ... | {
"Header 1": "**10L** *Suggested* **EXPERIMENTS**",
"Header 3": "IOM PROBLEMS",
"token_count": 397,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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- The history of spectroscopy is discussed in the following sources.
- Laitenen, H. A.; Ewing, G. W., eds. *A History of Analytical Chemistry,* The Division of Analytical Chemistry of the American Chemical Society: Washington, D.C., 1977, pp. 103–243.
- Thomas, N. C. "The Early History of Spectroscopy," *J. Chem. Educ.... | {
"Header 1": "**10N SUGGESTED READINGS**",
"token_count": 2047,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
Chem.* **1991,** *63,* 924A–931A.
- Slavin, W. "A Comparison of Atomic Spectroscopic Analytical Techniques," *Spectroscopy* **1991,** *6,* 16–21.
- Van Loon, J. C. *Analytical Atomic Absorption Spectroscopy.* Academic Press: New York, 1980.
- Walsh, A. "The Development of Atomic Absorption Methods of Elemental Analysis... | {
"Header 1": "**10N SUGGESTED READINGS**",
"token_count": 355,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
- 1. Method 417B in *Standard Methods for the Analysis of Water and Wastewater,* American Public Health Association: Washington, D.C.; 15 ed., 1981, pp. 356–360.
- 2. (a) Sheppard, N. In Andrews, D. L. Ed. *Perspectives in Modern Chemical Spectroscopy.* Springer-Verlag: Berlin, 1990, pp. 1–41; (b) Tyson, J. *Analysis: ... | {
"Header 1": "**10O REFERENCES**",
"token_count": 1526,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
- 26. Hach, C. C.; Bryant, M. "Turbidity Standards"; Technical Information Series-Booklet No. 12, Hach Company: Loveland, CO, 1995.
- 27. Method 4500-SO4 2–-E in *Standard Methods for the Analysis of Water and Wastewater,* American Public Health Association: Washington, D.C.; 20th ed., 1998, pp. 4–178 to 4–179.
- 28. L... | {
"Header 1": "**10O REFERENCES**",
"Header 3": "**460** Modern Analytical Chemistry",
"token_count": 786,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The diversity of interfacial electrochemical methods is evident from the partial family tree shown in Figure 11.1. At the first level, interfacial electrochemical methods are divided into static methods and dynamic methods. In static methods no current passes between the electrodes, and the concentrations of species in... | {
"Header 1": "**11A.1 Interfacial Electrochemical Methods**",
"token_count": 280,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Electrochemical measurements are made in an electrochemical cell, consisting of two or more electrodes and associated electronics for controlling and measuring the current and potential. In this section the basic components of electrochemical instrumentation are introduced. Specific experimental designs are considered ... | {
"Header 1": "**11A.2 Controlling and Measuring Current and Potential**",
"token_count": 1542,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In potentiometry the potential of an electrochemical cell is measured under static conditions. Because no current, or only a negligible current, flows while measuring a solution's potential, its composition remains unchanged. For this reason, potentiometry is a useful quantitative method. The first quantitative potenti... | {
"Header 1": "**11B Potentiometric Methods of Analysis**",
"token_count": 452,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Potentiometric measurements are made using a potentiometer to determine the difference in potential between a working or, indicator, electrode and a counter electrode (see Figure 11.2). Since no significant current flows in potentiometry, the role of the counter electrode is reduced to that of supplying a reference pot... | {
"Header 1": "**11B.1 Potentiometric Measurements**",
"token_count": 782,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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What are the anodic, cathodic, and overall reactions responsible for the potential in the electrochemical cell shown here? Write the shorthand notation for the electrochemical cell.
#### *SOLUTION*
The oxidation of Ag to Ag+ occurs at the anode (the left-hand cell). Since the solution... | {
"Header 1": "**EXAMPLE 11.1**",
"token_count": 2046,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
#### liquid junction potential
A potential that develops at the interface between two ionic solutions that differ in composition, because of a difference in the mobilities of the ions $(E_{li})$ .
<sup>\*</sup> See Chapter 6 for a review of activity.
lengths of their respective arrows. As a result, the solution ... | {
"Header 1": "**Liquid Junction Potentials** A **liquid junction potential** develops at the interface between any two ionic solutions that differ in composition and for which the mobility of the ions differs. Consider, for example, solutions of 0.1 M HCl and 0.01 M HCl separated by a porous membrane (Figure 11.6a).... |
In comparison to the SCE the Ag/AgCl electrode has the advantage of being useful at higher temperatures. On the other hand, the Ag/AgCl electrode is more prone to reacting with solutions to form insoluble silver complexes that may plug the salt bridge between the electrode and the solution.
#### **IIB.3** Metallic ... | {
"Header 1": "**Liquid Junction Potentials** A **liquid junction potential** develops at the interface between any two ionic solutions that differ in composition and for which the mobility of the ions differs. Consider, for example, solutions of 0.1 M HCl and 0.01 M HCl separated by a porous membrane (Figure 11.6a).... |
If metallic electrodes were the only useful class of indicator electrodes, potentiometry would be of limited applicability. The discovery, in 1906, that a thin glass membrane develops a potential, called a **membrane potential,** when opposite sides of the membrane are in contact with solutions of different pH led to t... | {
"Header 1": "**11B.4 Membrane Electrodes**",
"token_count": 2040,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The selectivity coefficient *K*H+/Na+ for Corning 015 is approximately 10–11. What error in pH is expected for a solution of 0.05 M NaOH.
#### *SOLUTION*
A solution of 0.05 M NaOH has an actual H+, [H+]act, concentration of 2 × 10–13 M and a pH of 12.7. The electrode responds, however, to both H+ and Na+, with the ... | {
"Header 1": "**EXAMPLE 11.4**",
"token_count": 2015,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Since EuF<sub>2</sub> provides only two F<sup>-</sup> ions, compared with three for LaF<sub>3</sub>, each EuF<sub>2</sub> produces a vacancy in the crystal lattice. Fluoride ions move through the membrane by moving into adjacent vacancies. The LaF<sub>3</sub> membrane is sealed into the end of a nonconducting plastic t... | {
"Header 1": "**EXAMPLE 11.4**",
"token_count": 590,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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| Analyte | Membrane Composition | Selectivity Coefficients <sup>a</sup> | | |
|------------------|--------------------... | {
"Header 1": "Table 11.2 Representative Examples of Polycrystalline Ion-Selective Electrodes",
"token_count": 1656,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
| Analyte | Membrane Composition | Selectivity Coefficients |
|------------------------------|--------------------------------------------------------------------|-----------------------------------------------------... | {
"Header 1": "Table 11.2 Representative Examples of Polycrystalline Ion-Selective Electrodes",
"token_count": 2035,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
Potentiometric biosensors have also been designed around other biologically active species, including antibodies, bacterial particles, tissue, and hormone receptors.
One example of an enzyme electrode is the urea electrode, which is based on the catalytic hydrolysis of urea by urease
$$CO(NH_2)_2(aq) + 2H_2O(\ell) ... | {
"Header 1": "Table 11.2 Representative Examples of Polycrystalline Ion-Selective Electrodes",
"token_count": 1824,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
If the electrode's response obeys the Nernst equation,
| Table 11.5 Representative Examples of Potentiometric Biosensors | | | | |
|-----------------------------------------------------------------|-----------------... | {
"Header 1": "Table 11.2 Representative Examples of Polycrystalline Ion-Selective Electrodes",
"token_count": 888,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
The concentration of Ca2+ in a water sample was determined by the method of external standards. The ionic strength of the samples and standards was maintained at a nearly constant level by making each solution 0.5 M in KNO3. The measured cell potentials for the external standards are shown in the following table.
| [... | {
"Header 1": "**EXAMPLE 11.6**",
"token_count": 2033,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
#### Determination of Fluoride in Toothpaste7
**Description of the Method.** The concentration of fluoride in toothpastes containing soluble F<sup>-</sup> may be determined with a F<sup>-</sup> ion-selective electrode, using a calibration curve prepared with external standards. Although the F<sup>-</sup> ISE is very ... | {
"Header 1": "Method 11.1",
"token_count": 1868,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
| Table 11.6 | | pH Values for Selected NIST Primary Standard Buffersa | | | | | ... | {
"Header 1": "Method 11.1",
"token_count": 1995,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Considerable interest has been shown in the development of biosensors for the field screening and monitoring of environmental samples for a number of priority pollutants.11
**Potentiometric Titrations** In Chapter 9 we noted that one method for determining the equivalence point of an acid–base titration is to follow ... | {
"Header 1": "Method 11.1",
"token_count": 210,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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**Scale of Operation** The working range for most ion-selective electrodes is from a maximum concentration of 0.1–1 M to a minimum concentration of 10–5 – 10–10 M. This broad working range extends from major to ultratrace analytes, and is significantly greater than many other analytical methods. For conventional ion-se... | {
"Header 1": "**11B.6 Evaluation**",
"token_count": 1249,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
In potentiometry, the potential of an electrochemical cell under static conditions is used to determine an analyte's concentration. As seen in the preceding section, potentiometry is an important and frequently used quantitative method of analysis. Dynamic electrochemical methods, such as **coulometry**, voltammetry, a... | {
"Header 1": "IIC Coulometric Methods of Analysis",
"token_count": 1898,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
For an exhaustive electrolysis in which 99.99% of the analyte is oxidized or reduced, the current at the end of the analysis, *t*e, may be approximated as
$$i \le (10^{-4})i_0$$
11.30
Substituting equation 11.30 into equation 11.29 and solving for *t*<sup>e</sup> gives the minimum time for an exhaustive electrolysi... | {
"Header 1": "IIC Coulometric Methods of Analysis",
"token_count": 594,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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A second approach to coulometry is to use a constant current in place of a constant potential (Figure 11.23). Controlled-current coulometry, also known as amperostatic coulometry or coulometric titrimetry, has two advantages over controlled-potential coulometry. First, using a constant current makes for a more rapid an... | {
"Header 1": "**11C.2 Controlled-Current Coulometry**",
"token_count": 2032,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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The time needed for an exhaustive electrolysis takes the place of the volume of titrant, and the switch for starting and stopping the electrolysis serves the same function as a buret's stopcock.
#### **IIC.3** Quantitative Applications
Coulometry may be used for the quantitative analysis of both inorganic and organ... | {
"Header 1": "**11C.2 Controlled-Current Coulometry**",
"token_count": 1220,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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OH O<sub>2</sub>N
$$+ 18H_3O^+ + 18e^ + 24H_2O$$
$+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$ $+ NH_2$
| Table 11.9 | .9 Representative Examples of Coulometric Redox Ti... | {
"Header 1": "**11C.2 Controlled-Current Coulometry**",
"token_count": 1579,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
| 10 R | Representative Examples of Coulometric Titrations Using Acid–Base, Complexation, |
|-----------|------|----------------------------------------------------------------------------------|
| | a | and Precipitation Reactions |
| Type of<br>React... | {
"Header 1": "**11C.2 Controlled-Current Coulometry**",
"token_count": 1887,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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**Description of the Method.** The concentration of $Cr_2O_7^{2-}$ in a sample is determined by a coulometric redox titration using $Fe^{3+}$ as a mediator and electrogenerated $Fe^{2+}$ as the "titrant." The end point of the coulometric redox titration is determined potentiometrically.
**Procedure.** The elect... | {
"Header 1": "Determination of Dichromate by a Coulometric Redox Titration<sup>13</sup>",
"token_count": 902,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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A 0.3619-g sample of tetrachloropicolinic acid, C6HNO2Cl4, is dissolved in distilled water, transferred to a 1000-mL volumetric flask, and diluted to volume. An exhaustive controlled-potential electrolysis of a 10.00-mL portion of this solution at a spongy silver cathode requires 5.374 C of charge. What is the value of... | {
"Header 1": "**EXAMPLE 11.9**",
"token_count": 1539,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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In **voltammetry** a time-dependent potential is applied to an electrochemical cell, and the current flowing through the cell is measured as a function of that potential. A plot of current as a function of applied potential is called a **voltammogram** and is the electrochemical equivalent of a spectrum in spectroscopy... | {
"Header 1": "**11D Voltammetric Methods of Analysis**",
"token_count": 257,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Although early voltammetric methods relied on the use of only two electrodes, modern voltammetry makes use of a three-electrode potentiostat, such as that shown in Figure 11.4. A time-dependent potential excitation signal is applied to the working electrode, changing its potential relative to the fixed potential of the... | {
"Header 1": "**11D.1 Voltammetric Measurements**",
"token_count": 2018,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
If this was all that occurred after the potential was applied, the result would be a brief surge of faradaic current that would quickly return to zero. However, although the concentration of Fe(CN)6 4– at the electrode surface is 0.50 mM, its concentration in the bulk of solution is zero. As a result, a concentration g... | {
"Header 1": "**11D.1 Voltammetric Measurements**",
"token_count": 1898,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
The shape of a voltammogram is determined by several experimental factors, the most important of which are how the current is measured and whether convection is included as a means of mass transport. Despite an abundance of different voltammetric techniques, several of which are discussed in this chapter, only three sh... | {
"Header 1": "**11D.3 Shape of Voltammograms**",
"token_count": 1589,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Figure 11.34
Determination of limiting current and halfwave potential in linear scan hydrodynamic voltammetry.
#### IID.5 Voltammetric Techniques
A number of voltammetric experiments are routinely used in quantitative and qualitative analyses. Several of these methods are briefly described in this section.
**Po... | {
"Header 1": "$i = \\frac{1}{2}i_{\\text{lim}}$ $i_{\\text{lim}}$ $E_{\\frac{1}{2}}$ Potential",
"token_count": 2016,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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17,18
volves the oxidation of the Hg electrode to $\mathrm{Hg_2^{2+}}$ , which then reacts with the analyte to form an insoluble film at the surface of the electrode. For example, when $\mathrm{Cl^-}$ is the analyte the deposition step is
$$2\text{Hg}(\ell) + 2\text{Cl}^-(aq) \rightleftharpoons \text{Hg}_2\text{... | {
"Header 1": "$i = \\frac{1}{2}i_{\\text{lim}}$ $i_{\\text{lim}}$ $E_{\\frac{1}{2}}$ Potential",
"token_count": 1202,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Quantitative voltammetry has been applied to a wide variety of sample types, including environmental samples, clinical samples, pharmaceutical formulations, steels, gasoline, and oil.
**Selecting the Voltammetric Technique** The choice of which voltammetric technique to use depends on the sample's characteristics, in... | {
"Header 1": "**11D.6 Quantitative Applications**",
"token_count": 2000,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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#### EXAMPLE II.12
The differential pulse polarographic analysis of mixtures of indium and cadmium in 0.1 M HCl is complicated by the overlap of their respective voltammograms.<sup>20</sup> The peak potential for indium is at −0.557 V, and that for cadmium occurs at a potential of −0.597 V. When a 0.800-ppm indium ... | {
"Header 1": "**11D.6 Quantitative Applications**",
"token_count": 2025,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
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Because the concentration of lead in blood is so small, anodic stripping voltammetry frequently is the method of choice. The analysis is complicated, however, by the presence of proteins that may adsorb at the surface of the mercury electrode, inhibiting either the deposition or stripping of lead. In addition, proteins... | {
"Header 1": "**11D.6 Quantitative Applications**",
"token_count": 614,
"source_pdf": "datasets/websources/biochem/Modern analytical chemistry by David Harvey.pdf"
} |
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