Non-aqueous determination of inorganic salts

The procedures suggested for the determination of salts in nonaqueous solutions have been limited almost wholly to the analysis of amine salts and salts of the alkali and alkaline earth metals. Other salts are usually assayed by a variety of specific cationic or anionic procedures. By the proposed method, salts of all types can be determined titrimetrically so long as the compound will participate in an anion-exchange reaction. The procedure simply involves acidification of the salt with an excess of a strong acid, addition of a nonaqueous solvent and a differentiating potentiometric titration. Carbonate and hydroxide impurities do not interfere in the analysis and the solubility difficulties experienced in other nonaqueous procedures are not encountered in this method.     

Determination of the solubility of inorganic salts by headspace gas chromatography

This work reports a novel method for determination of salt solubility using headspace gas chromatography. A very small amount of volatile compound (such as methanol) is added in the studied solution. Due to the molecular interaction in the solution, the vapor-liquid equilibrium (VLE) partitioning coefficient of the volatile species will change with different salt contents in the solution. Therefore, the concentration of volatile species in the vapor phase is proportional to the salt concentration in the liquid phase, which can be easily determined by headspace gas chromatography. Until the salt concentration in the solution is saturated, the concentration of volatile compound in the vapor phase will continue to increase further and a breakpoint will appear on the VLE curve. The solubility of the salts can be determined by the identification of the breakpoint. It was found that the measured solubility of sodium carbonate and sodium sulfate in aqueous solutions is slightly higher (about 6-7%) than those reported in the literature method. The present method can be easily applied to industrial solution systems.     

A new method for disintegration studies of rapid disintegrating tablet

The aim of this study was to develop a simple and suitable disintegration method specific for rapid disintegrating tablets (RDTs). The new disintegration method that we propose employs a rotary shaft to exert mechanical pressure on the RDT. To assess our method, we manufactured several placebo RDTs and exposed them to severe storage conditions (60 degrees C/75%RH for 1 week) in order to obtain RDTs with a wide range of disintegration times. These placebo RDTs were utilized to compare the disintegration times obtained by several methods, including the proposed method. As expected, the disintegration time of the placebo RDTs in human sensory test varied widely. The disintegration times determined by the conventional disintegration test were in good correlation to those in human sensory test, but the slope was far from 1 (0.241). There was no correlation between the disintegration time of RDTs in human sensory test and those determined by the conventional dissolution test. In contrast, we acquired good correlation between the disintegration times obtained with the new method and those in human sensory test, and the slope was very close to 1 (0.858). We attribute this to the use of mechanical stress in the new method, similar to that the RDT is subject to in the oral cavity. We therefore concluded that the proposed method was suitable for the measurement of the disintegration time of RDTs. This new method might provide a valuable approach for the establishment of the official disintegration test for RDTs in the future.     

Application of selenium salts in inorganic analysis

The gravimetric determination of metals as selenides is proposed. Owing to the rapid atmospheric oxidation of sodium selenide and the toxic nature of hydrogen selenide, special apparatus is required. The methods are analogous to precipitation of sulphides. Arsenic, tin, antimony, platinum, ruthenium, palladium, rhodium, rhenium, mercury, silver and gold can be determined. The thermolysis of precipitates formed with arsenic, antimony, mercury, silver, rhenium, platinum, ruthenium, palladium and rhodium has been studied.     

Application of selenium salts in inorganic analysis

The gravimetric determination of metals as selenides is proposed. Owing to the rapid atmospheric oxidation of sodium selenide and the toxic nature of hydrogen selenide, special apparatus is required. The methods are analogous to precipitation of sulphides. Arsenic, tin, antimony, platinum, ruthenium, palladium, rhodium, rhenium, mercury, silver and gold can be determined. The thermolysis of precipitates formed with arsenic, antimony, mercury, silver, rhenium, platinum, ruthenium, palladium and rhodium has been studied.     

Improvement on the performance N-(3-methoxypropyl)acrylamide polymer-gel dosimeter by the addition of inorganic salt for application in radiotherapy dosimetry

Journal of Radioanalytical and Nuclear Chemistry - The effect of lithium chloride (LiCl) on the dose–response performance of the N-(3-methoxypropyl)acrylamide polymer-gel dosimeter (NMPAGAT)...     

Regiochemistry of the addition of mercury salts to bornylene

The dependence of the regiochemistry of the mercuration of bornylene on the nature of the mercurating reagent and on the solvent has been found. The structures of the intermediate and transition state in these reactions have been proposed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 501–505, March, 1994.     

A novel method for predicting disintegration time in the mouth of rapidly disintegrating tablet by compaction analysis using TabAll

A tableting process analyzer (TabAll) was used to predict disintegration time in the mouth of rapidly disintegrating tablet. Analyzer profiles recorded upper punch displacement and die wall force encountered during tablet processing. Changes in the mixing ratio of spherical sugar granules and microcrystalline cellulose or lactose affected upper punch displacement and die wall force profiles. Analysis of the compaction process revealed a strong association between disintegration time in the mouth and stationary time, relaxation time of upper punch displacement, and relaxation time of die wall force; disintegration time in the mouth decreased as the three parameters increased. Thus, analysis of the compaction process is useful for predicting disintegration time in the mouth of rapidly disintegrating tablet, which can assist the formulation of new rapidly disintegrating tablets.     

Thermal dehydration of inorganic salts in water-saturated nitrogen

The thermal dehydrations of CoSO₄ · 6H₂O, NiSO₄ · 6H₂O and MnSO₄ · H₂O have been investigated by TG, DTG, and DTA in water-saturated nitrogen. The starting temperatures and the “activation energy” values for each step are reported.     

Solubility of inorganic salts in pure ionic liquids

The solubility of different conventional salts in several room-temperature ionic liquids – containing ammonium, phosphonium or imidazolium cations combined with acetate, sulfate, sulfonate, thiocyanate, chloride, tetracyano-borate, tris(pentafluoroethyl)trifluoro-phosphate, l-lactate, bis(trifluoromethylsulfonyl)imide or trifluoromethylsulfonate anions – were screened using a visual detection method. The most promising mixtures were then re-measured using an ATR–FTIR (Attenuated Total Reflection Fourier Transform Infra Red) spectroscopy technique in order to accurately and quantitatively determine the corresponding solubility at 298.15 K.     

Complex formation of inorganic salts withβ-cyclodextrin

The interactions between some alkali halides, perchlorates and sulfates and-cyclodextrin (cycloheptaamylose, CD) have been investigated by solubility, spectrophotometric, thermoanalytical and preparative methods. The main conclusions are as follows. (i) The most pronounced interaction occurs with the anions; in dilute solutions this can be characterized as the formation of 1 : 1 complexes. In more concentrated solutions ternary associates and more complicated ones (involving the cations as well) are also formed. (ii) Changes in the activity coefficients or of the activity of water may also have some role in the phenomena, but it cannot be dominant: differences according to the individual properties of the anions are much more pronounced than to those of the cations or to changes of the ionic strength. (iii) Regarding the type of complex formation, real inclusion and outer sphere interactions (via hydrogen bonds) are also probable.     

Spectroscopic characterization of aqueous microdroplets containing inorganic salts

We have developed and studied methods to characterize the time-varying composition of liquid microdroplets, under controlled changes to environmental conditions, using Raman tweezers. This work has focussed on measurements of inorganic salts, such as nitrate and sulfate anions, which comprise a major fraction of the dissolved solutes in atmospheric aerosols. The experimental Raman intensities for the anions of inorganic salts in optically tweezed droplets were found to be in good agreement with theoretical estimates of photon scattering. The detection limit for sodium nitrate salt in a single particle was found to be ~4 pg. The mass of an inorganic salt in the droplet can be estimated from the Raman intensity of the anion bands using a calibration curve which is independent of droplet volume. The volume of the droplet, and concentration of solute, can be found directly from the spacing of morphology dependent resonances in the Raman band of water, or indirectly from the integrated-intensity of the Raman band for the solvent. The later strategy eliminates the uncertainty in the collection efficiency of Raman-scattered light related to varying particle sizes.     

Improvement in LC-MS calibration by addition of fragment signals

Liquid chromatography-mass spectrometry has become a powerful analytical tool, with high selectivity and sensitivity. Usually in this technique, the calibration function is estimated from the molecular peak signal. This report describes the improvement in sensitivity when the signals from several fragments in addition to the molecular peak are used to establish the calibration function. The influence of the dwell time has also been analysed as an important instrumental parameter that influences the signal range, and consequently, the sensitivity. The calibration function obtained by adding fragment signals was used to estimate the instrumental detection limit using three different procedures, comparing and discussing the results obtained.