Chloride ion, detection

Chloride ion detection for corrosion monitoring. Tang and Wang [40] measured chloride ions in a typical concrete sample immersed in saltwater solutions with different weight concentrations ranging from 0% to 25%. The LPG sensor exhibited a linear decrease in the transmission loss and resonance wavelength shift when the concentration increased. The measurement accuracy for the concentration of salt in water solution was estimated to be 0.6% and the limit of detection for chloride ions was about 0.04%. 

Qualitative. The classic method for the quaUtative determination of silver ia solution is precipitation as silver chloride with dilute nitric acid and chloride ion. The silver chloride can be differentiated from lead or mercurous chlorides, which also may precipitate, by the fact that lead chloride is soluble ia hot water but not ia ammonium hydroxide, whereas mercurous chloride turns black ia ammonium hydroxide. Silver chloride dissolves ia ammonium hydroxide because of the formation of soluble silver—ammonia complexes. A number of selective spot tests (24) iaclude reactions with /)-dimethy1amino-henz1idenerhodanine, ceric ammonium nitrate, or bromopyrogaHol red [16574-43-9]. Silver is detected by x-ray fluorescence and arc-emission spectrometry. Two sensitive arc-emission lines for silver occur at 328.1 and 338.3 nm. 

Impurities in bromine may be deterrnined quantitatively (54). Weighing the residue after evaporation of a bromine sample yields the total nonvolatile matter. After removing the bromine, chloride ion may be deterrnined by titration with mercuric nitrate, and iodide ion by titration with thiosulfate water and organic compounds may be detected by infrared spectroscopy sulfur may be deterrnined turbidimetricaHy as barium sulfate and heavy metals may be deterrnined colorimetricaHy after conversion to sulfides. 

The amount of reddish-purple acid-chloranilate ion liberated is proportional to the chloride ion concentration. Methyl cellosolve (2-methoxyethanol) is added to lower the solubility of mercury(II) chloranilate and to suppress the dissociation of the mercury(II) chloride nitric acid is added (concentration 0.05M) to give the maximum absorption. Measurements are made at 530nm in the visible or 305 nm in the ultraviolet region. Bromide, iodide, iodate, thiocyanate, fluoride, and phosphate interfere, but sulphate, acetate, oxalate, and citrate have little effect at the 25 mg L 1 level. The limit of detection is 0.2 mg L 1 of chloride ion the upper limit is about 120 mg L . Most cations, but not ammonium ion, interfere and must be removed. 

Evidence for molecular chlorine or bromine as the attacking species in these cases is that acids, bases, and other ions, especially chloride ion, accelerate the rate about equally, though if chlorine dissociated into Cl" and Cl , the addition of chloride should decrease the rate and the addition of acids should increase it. Compound 27 has been detected spectrally in the aqueous bromination of phenol. ... 

The dominant species of Ce(IV) existing under the reaction conditions is 00(804)3 and the activated complexes for the two paths must have compositions 0(804)2 Br and 00(804)261 . The latter path is subject to chloride-ion catalysis of the form = A q-1-A [OI ] which suggests an activated complex 0e(804)201Br2 . 8I0W oxidative breakdown of the complexes containing bromide gives Oe(III) and Br atoms or -BrJ. The latter go on to form molecular bromine however, their presence has been detected in this reaction from their ability to add to butadiene to form dibromooctadienes . 

The methods most commonly used to detect hydrogen sulfide in environmental samples include GC/FPD, gas chromatography with electrochemical detection (GC/ECD), iodometric methods, the methylene blue colorimetric or spectrophotometric method, the spot method using paper or tiles impregnated with lead acetate or mercuric chloride, ion chromatography with conductivity, and potentiometric titration with a sulfide ion-selective electrode. Details of commonly used analytical methods for several types of environmental samples are presented in Table 6-2. 

The apparent rate constant kapp depends on the concentration of hydroxide ion as is shown in Fig. 1. The absorption maxima of TcCl2(acac) 2 in chloroform appear at 281,314(sh), 340(sh), 382 and 420 nm. On the other hand, the spectrum of the aqueous phase exhibits absorption maxima at 292,350 and 540 nm. The absorbances at 350 and 540 nm increase with time, but decrease after reaching maxima. This suggests that the chemical species which is formed by the back-extraction of TcCl2(acac)2 decomposes with time. In order to clarify the behavior of chloride ion liberated from the complex, an electrochemical method was introduced for the homogeneous system. In acetonitrile, no detectable change in the spectrum of TcCl2(acac)2 was observed. On the addition of an aqueous solution of hydroxide, however, the brown solution immediately turned red-violet, and exhibited absorption maxima at 292,350 and 540 nm. The red-violet... 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

Iodide was determined by an iodide-selective electrode (Ag2S/AgI) after other anions were separated by a rhodium nitrate element [101]. However, the electrode that was stabilised by 0.5 xm iodide responded to chloride ions in seawater, and the detection limit of iodide was 22 xg/l. 

Hardy effect.248-249 The internal return part of the ionization equilibrium is particularly hard to detect since it is almost completely independent of the concentration of anything in the bulk of the solution outside of the solvent cage. The extent of internal return will depend on the reactivity of the cage walls and their resistance to the escape of either ion. Unless internal return has been eliminated by the use of an extremely reactive cage wall, the measured rate is not that of the ionization but the lesser rate of ion pair dissociation. In the case of the acetolysis of a, a-dimethylallyl chloride (XXXIX), internal return is detectable by virtue of the fact that the chloride ion can return to either of two allylic carbon atoms.248... 

In Nebraska, state regulations require that the chemical makeup of animal feed sold in the state be accurately reflected on the labels found on the feed bags. The Nebraska State Agriculture Laboratory is charged with the task of performing the analytical laboratory work required. An example is salt (sodium chloride) content. The method used to analyze the feed for sodium chloride involves a potentio-metric titration. A chloride ion-selective electrode in combination with a saturated calomel reference electrode is used. After dissolving the feed sample, the chloride is titrated with a silver nitrate standard solution. The reaction involves the formation of the insoluble precipitate silver chloride. The electrode monitors the decrease in the chloride concentration as the titration proceeds, ultimately detecting the end point (when the chloride ion concentration is zero). 

Anions play key roles in chemical and biological processes. Many anions act as nucleophiles, bases, redox agents or phase transfer catalysts. Most enzymes bind anions as either substrates or cofactors. The chloride ion is of special interest because it is crucial in several phases of human biology and in disease regulation. Moreover, it is of great interest to detect anionic pollutants such as nitrates and phosphates in ground water. Design of selective anion molecular sensors with optical or electrochemical detection is thus of major interest, however it has received much less attention than molecular sensors for cations. 

Example The extraordinary stable trityl ion, PhsC, m/z 243, tends to dominate mass spectra (Chap. 6.6.2). Thus, neither the El spectrum of chlorotriphenyl-methane nor that of its impurity triphenylmethanol show molecular ions (Fig. 8.11). An isobutane PICI spectrum also shows the trityl ion almost exclusively, although some hint is obtained from the Ph2COH ion, m/z 183, that cannot be explained as a fragment of a chlorotriphenylmethane ion. Only FD reveals the presence of the alcohol by its molecular ion at m/z 260 while that of the chloride is detected at m/z 278. Both molecular ions undergo some OH or Cl loss, respectively, to yield the Ph3C fragment ion of minor intensity. 

Photolysis of an aqueous solution containing chloroform (314 pmol) and the catalyst [Pt(cohoid)/Ru(bpy) /MV/EDTA] yielded the following products after 15 h (mol detected) chloride ions (852), methane (265), ethylene (0.05), ethane (0.52), and unreacted chloroform (10.5) (Tan and Wang, 1987). In the troposphere, photolysis of chloroform via OH radicals may yield formyl chloride, carbon monoxide, hydrogen chloride, and phosgene as the principal products (Spence et al., 1976). Phosgene is hydrolyzed readily to hydrogen chloride and carbon dioxide (Morrison and Boyd, 1971). 

Urinary excretion of C1 was observed in rats that had been administered Alcide, an antimicrobial compound consisting of sodium chlorite and lactic acid that form chlorine dioxide when mixed (Scatina et al. 1984). The rats had received 10 daily dermal applications, followed by an application of radiolabeled Alcide. Urinary excretion was greatest in the first 24 hours post application the half-time of urinary elimination was 64 hours. The excreted radioactivity consisted of approximately equal portions of chloride ion and chlorite. No radioactivity was detected in feces or expired air. 

Elemental composition Cr 42.31%, Cl 57.69%. The metal may be analyzed by AA, ICP, or other instrumental techniques. Chloride may be measured by ion chromatography or by using a chloride ion selective electrode. Because of the blue color of its aqueous solution, end point detection in titrimetric methods may be difficult. 

Elemental composition Cu 64.18%, Cl 35.82%. Copper(I) chloride is dissolved in nitric acid, diluted appropriately and analyzed for copper by AA or ICP techniques or determined nondestructively by X-ray techniques (see Copper). For chloride analysis, a small amount of powdered material is dissolved in water and the aqueous solution titrated against a standard solution of silver nitrate using potassium chromate indicator. Alternatively, chloride ion in aqueous solution may be analyzed by ion chromatography or chloride ion-selective electrode. Although the compound is only sparingly soluble in water, detection limits in these analyses are in low ppm levels, and, therefore, dissolving 100 mg in a liter of water should be adequate to carry out aU analyses. 

Lubiprostone has used as a novel PG compound for an oral treatment of constipation with a unique action directed to the target tissue, although it has low systemic availability following oral administration. It activates a locally acting chloride channel, which is a normal constituent of the apical membrane of the human intestine, and enhances a chloride-rich intestinal fluid secretion without altering sodium and potassium concentration in the serum. In fasted rats administered doses of 1, 10, or lOOpg/kg of the compound, dose-dependent increases in the concentration of chloride ions in the bowel were detected, indicating that the compound opens chloride channels and promotes chloride ion transport in vivo [45]. 

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