Precipitation Of Silver Chloride Research Articles

Determination of Pyrophosphate based on Inhibition of Crystallization of Silver Chromate

Abstract The inhibitory effect of pyrophosphate on the precipitation of silver chromate has been studied by turbidimetry for analytical uses. The new method was applicable to the range 0.3 - 1.5 μg/mL with a precision of 4%. Elimination of the interference caused by chloride was accomplished through precipitation of silver chloride. Finally, the method was applied to the determination of pyrophosphate used as an additive in commercial food samples.

Energy dispersive X-ray fluorescence analysis of chloride in reforming catalysts

A relatively less expensive Phillips PV 9500/SY 585 automatic energy dispersive X-ray fluorescence (EDXFR) spectrometer with rhodium target, was modified using a commercial kitchen aluminium wrapping foil filter, for the determination of chloride in bifunctional reforming catalysts. Quantitation of chloride was carried out by the Claisse-Quintin method with a catalyst sample of known chloride content as an external standard. The results of EDXRF chloride analysis of different catalyst samples, containing varying amounts of percent carbon and chloride, compared well (p>0.75) with those obtained by silver chloride precipitation method. The small values of percent relative standard deviations at 0.4 to 4.5% showed a good reproducibility of the method. With the total analysis time of a few minutes combined with no sample preparation, the present method seems to be superior as compared to presently employed methods of chloride analysis in reforming catalysts.

Electrorefining of high silver content gold bullion using pulsating currents

High silver contents (>7%) in gold bullion markedly influence electrolytic refining processes. The silver chloride precipitate, formed on the anodic surface, give rise to lower process efficiencies, explained by chloride ion oxidation to the detriment of the gold dissolution reaction. In this study the use of pulsating currents on the electrorefining of a 17.1% silver-gold bullion was investigated. Periodic Reverse Current (PRC) and Asymmetric Alternate Current (AAC) parameters were varied as well as the hydrochloric acid concentration in the electrolyte. The initial laboratory results were confirmed in pilot scale at the Brazilian Mint facilities.

Reverse flow injection analysis: Determination of trace amounts of metals using an on-line preconcentration technique

Determination of metal ion concentrations by reversed flow injection analysis using precipitation as a preconcentration technique is presented. The precipitate formed from the reaction of the cation and the anion, in a Tygon tube containing glass beads connected to the atomic absorption spectrophotometer, is dissolved by injection of a solution of a suitable dissolving reagent. The dissolving reagent dissolves the precipitate and the cation is transported to the atomic absorption spectrophotometer, yielding the signal. Three cations were tested to demonstrate the feasibility of the procedure: silver, calcium, and iron which were precipitated as silver chloride, calcium carbonate, and ferric hydroxide, respectively. Three dissolving reagents were investigated with silver chloride precipitate: ammonia, thiosulfate ion, and cyanide ion. Three other reagents were also used to dissolve ferric hydroxide precipitate: hydrochloric acid, phosphoric acid, and nitric acid. One reagent, hydrochloric acid, was used as a dissolving agent for calcium carbonate precipitate. Detection limits were 5 × 10 −3, 4 × 10 −2, and 8 × 10 −4 ppm, respectively, for silver, iron, and calcium using thiosulfate, phosphoric acid, and hydrochloric acid as respective dissolving agents. The method could be applied easily to many routine analyses, such as water analysis due to its rapidity, precision, and small reagent consumption.

Indirect atomic absorption spectrometric determination of mixtures of chloride and iodide by precipitation in an unsegmented flow system

Chloride and iodide are injected into a carrier silver nitrate and the precipitates formed are retained on a stainless-steel filter, so that total chloride and iodide can be determined by the decrease in the atomic absorption signal for silver. The silver chloride precipitate is subsequently dissolved with ammonia and chloride only is determined. Iodide is determined by difference. Mixtures of these anions at μg ml −1 levels can be determined for chloride/iodide ratios from 7.5:1 to 1:60, with a sampling frequency of ca. 10 h −1. Applications to the determination of chloride in foodstuffs and wines are described. Up to 10 samples per hour can be handled and 50–100 samples can be run before the filter must be cleaned.

Indirect atomic absorption determination of chloride by continuous precipitation of silver chloride in a flow injection system

A method is proposed for the determination of chloride by flow injection atomic absorption spectrometry. The chloride forms a precipitate with silver nitrate which is retained on a stainless-steel filter. Two unsegmented flow configurations involving normal and reversed flow injection are proposed. By using normal flow injection, chloride was determined in the range 3–100 µg ml–1, with a sampling rate of 50 h–1 and relative standard deviation of 2.0%. In reversed flow injection, chloride was determined in the range 0.3–10 µg ml–1 with a sampling frequency of 200 h–1 and relative standard deviation of 3.5%. Both methods have been applied to the determination of chloride in water samples, and the results have been critically compared with those obtained by the batch method.

The recovery of silver after lead collection and perchloric acid parting

A method is described for determination of silver, which eliminates cupellation. The sample is fused with lead flux and the resulting lead assay button is parted with perchloric acid after heating at ca. 180°C. Complete precipitation of silver chloride is attained by dilution and overnight standing. After filtration and dissolution of the precipitate in ammonia, silver is determined by atomic absorption spectrometry. Results on samples of varying nature and composition are higher than those obtained by the classical lead-cupellation method.

SILVER CHLORIDE MICROCRYSTALS SUSPENSIONS IN MICROEMULSION MEDIA

ABSTRACT A study of the precipitation of silver chloride in a micro-emulsion medium is presented. Measurements of turbidity, X-ray diffraction and small angle scattering show, the rapid formation of small crystals, about 60 °A in diameter wliich show no further growth and aggregate only slowly ; the stabilization of these solid particle suspensions, of steric or electrostatic origin, is increased by six orders of magnitude in comparison with aqueous colloidal solutions

Volumetric Method for Determining Traces of Organic Chlorine in Lipids

The official AOAC method for determining chlorine in cake flour lipids has been modified to determine chlorine in lipids of animal carcasses cooled with chlorinated water. The sensitivity of the method has been improved 1000-fold to attain a detection limit of 2 ppm Cl in lipids. Recovery of the fine silver chloride precipitate was improved through centrifugation rather than filtration. The official method also did not take into consideration that when the silver chloride precipitate is exposed to light, it is converted to free chlorine and silver. Recovery of organic chlorine ranged from 84.6% at 4.1 ppm to 100.1% at 100 ppm. A number of samples of commercially chlorinated beef, pork, and chicken and laboratory-chlorinated chicken were analyzed by this method. In all cases where the level of chlorination was sufficient to result in a chlorine level in lipids in excess of 2 ppm, the chlorine content of the carcass lipids was measurable.

A nongravimetric method for the routine determination of chloride in carbonate rocks

The method described depends upon the precipitation of silver chloride from a known amount of silver nitrate followed by the determination by atomic absorption spectroscopy of Ag remaining in solution. The coefficient of variation (ratio of standard deviation to mean) varies from 5.3% at 100 ppm to 1.5% at 900 ppm.

Determination of sodium and chlorine in pure water by neutron activation analysis

Neutron activation analysis was applied to determine sodium and chlorine in high purity water samples. After irradiation of the sample,38Cl was purified from82Br and other nuclides by carbon tetrachloride extraction and silver chloride precipitation, and24Na was separated from other alkali elements and other nuclides by adsorption of24Na on HAP. The activities of both elements were measured by conventional G.M. counter. The contamination of the elements from container walls during neutron irradiation and the interference with38Ar(n, p)38Cl reaction on argon dissolved in water were also examined. Water samples containing 3 ppb of chlorine could not be determined accurately, owing to the above mentioned interfering reaction.

Micromethod for analysis for chloride in physiological fluids.

A micromethod for the analysis for chloride, based on the chemical precipitation of silver chloride by radial diffusion through agar gel containing silver nitrate, is described. The method is simple to run, requires little or no instrumentation, and requires only 10 mul of sample. Results by coulometric titration (Buchler Cotlove Chloridometer) correlated well for serum (r = 0.961), urine (r = 0.997), cerebrospinal fluid (r = 0.991), and sweat (r = 0.998). Other halide ions or protein do not interfere. Precision studies gave a within-day reproducibility (CV) of 1.3% and a day-to-day variability of 2.1% for a serum sample averaging 115 mmol/liter.

Preparation and properties of the tetra-aquaplatinum(II) ion in perchloric acid solution

Dilute solutions of the square-planar tetra-aqua complex pt(H 2O) 4 2+ have been prepared in a 1.00 M perchloric acid medium by addition of excess silver(I) perchlorate to potassium tetrachloroplatinate(II), equilibration at 70°C, filtration of the silver chloride precipitate, and subsequent separation of the excess silver from the solution by electrolysis. The complex has also been prepared by addition of mercury(II) perchlorate to tetrachloroplatinate(II) solutions. The UV and visible absorption spectrum of the complex has been recorded and its hydrolysis qualitatively studied. The experiments indicate that Pt(H 2O) 4 2+ is a weak acid with pK a>2.5. A while, amphoteric hydroxide of platinum(II) is precipitated in the pH region 4 to 10.

Light and electron microscopy localization of chloride ions in cells of Salicornia pacifica var. utahensis

Light and electron microscopy was used to determine the distribution of chloride ions in cells and tissues of Salicornia pacifica Standl, var. utahensis (Tidestrom) Munz. Chlorenchyma cells with chloroplasts around the periphery and sclereid-like cells with distinct wall thickenings which extended from the anastomosing vascular system to near the epidermis were present in the cortex. The vascular bundles or stelar strands were surrounded by several layers of large parenchyma cells. Tissues were treated with silver acetate for silver chloride precipitation. Silver chloride precipitation sites were present in all cell types. Precipitation sites were readily evident in the vacuoles but not in other organelles.

A silver chloride/sulphide amplification reaction for the microdetermination of chloride ion

An amplification procedure is described for the determination of 0.05–10 mg amounts of chloride ion. The amplification procedure is an arithmetic one based on precipitation of silver chloride, metathesis with sodium sulphide to silver sulphide and sodium chloride, followed by reprecipitation of the chloride, etc. The final yield of Ag2S is converted into AgCl for weighing. In this way, precipitates of silver chloride which are too small to be used for gravimetric purposes can be amplified to produce weighable amounts of silver chloride. The method is precise and gives accurate results in comparison with other methods at low concentrations. The process may also be automated.

Precipitation of silver chloride from homogeneous solution

Precipitation of silver chloride from homogeneous solution

Precipitation of silver chloride from homogeneous solution

Precipitation of silver chloride from homogeneous solution

Precipitation of silver chloride from homogeneous solution

The rate of precipitation of silver chloride, produced by the hydrolysis of allyl chloride in aqueous silver nitrate solution and followed by conductance measurements (Part 1), is considered in terms of theHam and theFrisch andCollins theories of crystal growth. In the early stages the precipitation is controlled by an interface process and the rate constants are evaluated for the growth of particles in systems where the [Ag+]/[Cl−] ratio varies over a wide range. In the later stages the growth rate is slower than predicted either by interface or diffusion controlled mechanisms. Particle charge is an important factor in determining both the growth kinetics and the nature of the final precipitate.

Pulse radiolysis study of silver chloride formation and precipitation

Stable ions were formed by a 1μs pulse of high-energy electrons. Reactions and precipitate formation of these ions were followed. The formation kinetics of the AgCl 2-complex were studied by irradiating aqueous chloroacetic acid plus silver acetate solutions of appropriate concentrations. The observations were in agreement with a consecutive reversible mechanism of the form Ag ++Cl-⇋AgCl; AgCl+Cl-⇋AgCl 2- where the first stage represented a pre-equilibrium to the second one and the forward and reverse rate constants of the second stage were (4·1 ± 0·1) × 10 8 1 mol −1 s −1 and (4·7 ± 0·12) × 10 6 1 mol −1 s −1, respectively. Some indications of the formation of a silver organic compound were observed. The period of incubation before precipitate formation t 0 was determined. This obeyed the general rule log t 0 = −n log c + const. where c̄ is the geometrical mean of the initial ion concentration, and n = 8·9 ± 0·5 was found. Similar studies of the iodoacetic acid plus silver acetate system indicated the formation of the complex AgI 2−.

The demonstration of chloride ions in the “chloride cells” of the gills of eels (Anguilla anguilla L.) adapted to sea water

The ultrastructure of “chloride cells” in the gills of eels kept in artificial sea water and of a control animal kept in fresh water was studied. In addition to glutaraldehydeosmium tetroxide and simple osmium tetroxide fixation, a special method for the demonstration of chloride ions was used (Komnick, 1962, 1963). Based on the principle of silver chloride precipitation in the presence of chloride ions, the procedure showed positive results in the “chloride cells” of eels adapted to sea water. Smooth-surfaced tubules of the endoplasmic reticulum contained a material of medium to strong electron density, that was often in communication with the plasma membrane. The same material, always of very high density, was present in the intercellular spaces, thus forming conspicuous lines around cells. The silver precipitate was found very often in large quantities in the “pits” of “chloride cells”, having thereby the aspect of a secretory product. However, a direct communication between the system of endoplasmic reticulum tubules containing the silver reaction product with the above-mentioned masses of silver chloride was not demonstrated.