Determination of the Glass Electrode Parameters by Means of Potentiometric Titration of Acetic Acid in Aqueous Sodium or Potassium Chloride Solutions at 25°C

Single-ion activity coefficient equations are presented for the calculation of stoichiometric (molality scale) dissociation constants K _m for acetic acid in aqueous NaCl or KCl solutions at 25°C. These equations are of the Pitzer or Hückel type and apply to the case where the inert electrolyte alone determines the ionic strength of the acetic acid solution considered. K _m for a certain ionic strength can be calculated from the thermodynamic dissociation constant K _a by means of the equations for ionic activity coefficients. The data used in the estimation of the parameters for the activity coefficient equations were taken from the literature. In these data were included results of measurements on galvanic cells without a liquid junction (i.e., on cells of the Harned type). Despite the theoretical difficulties associated with the single-ion activity coefficients, K _m can be calculated for acetic acid in NaCl or KCl solutions by the Pitzer or Hückel method (the two methods give practically identical K _m values) almost within experimental error at least up to ionic strengths of about 1 mol-kg^–1. Potentiometric acetic acid titrations with base solutions (NaOH or KOH) were performed in a glass electrode cell at constant ionic strengths adjusted by NaCl or KCl. These titrations were analyzed by equation E = E _o + k(RT/F) ln[m(H⁺)], where m(H⁺) is the molality of protons, and E is the electromotive force measured. m(H⁺) was calculated for each titration point from the volume of the base solution added by using the stoichiometric dissociation constant K _m obtained by the Pitzer or Hückel method. During each base titration at a constant ionic strength, E _o and k in this equation were observed to be constants and were determined by linear regression analysis. The use of this equation in the analysis of potentiometric glass electrode data represents an improvement when compared to the common methods in use for two reasons. No activity coefficients are needed and problems associated with liquid junction potentials have been eliminated.     

A Class of Rational Arithmetical Functions with Combinatorial Meanings

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Evaluation of the fundamental sampling error in the sampling of particulate solids

Chemical analysis is a multi-stage process, which starts with primary sampling and ends with evaluation of the resuts. Especially in trace analysis and microanalysis of solid materials, sampling can far outweigh all other sources of error. For estimating the reliability of complete analytical procedures, a method is needed which can be used to estimate the errors made in the primary and the secondary sampling and sample preparation steps. Based on Gy's theory of sampling, a computer program (SAMPEX) was written for the solution of practical sampling problems. The method involves the estimation of the sampling constant, C. For well-characterized materials, C can be estimated from the material properties. If the necessary material properties are difficult to estimate, C can be evaluated experimentally. The program can be used to solve the following problems: minimum sample size for a tolerated relative standard deviation of the fundamental sampling error; relative size for a tolerated for a given sample size; maximum particle size of the material for a specified standard deviation and sample size; balanced design of a multi-stage sampling and sample-reduction process; and sampling for particle size determination.     

Electron impact ionization mass spectrometry and intramolecular cyclization in 2-substituted pyrimidin-4(3H)-ones

Electron impact ionization mass spectrometry indicates that the behavior of W-unsubstituted pyrirnidin-4-ones with CH₂-R type substitution at C-2 differs from homologs that are N-substituted and/or 2-aryl- or 2-methyl-substituted. A dominant intramolecular cycliza-tion was found to occur between 3ZV (in agreement with the predominance of the 3NH tautomers) and the ortho positions of the aryl moiety in compounds with a CH₂-aryl substitution at C-2. Theoretical calculations with an AMI SCFR method on 2-, 6-, and 2, 6-disubstituted pyrimidin-4-ones support the mass spectrometric observations.     

Speciation of halogenides and oxyhalogens by ion chromatography-inductively coupled plasma mass spectrometry

A speciation method utilizing ion chromatography coupled with inductively coupled plasma mass spectrometry is described for simultaneous analysis of eight halogenides and oxyhalogens: chloride, chlorite, chlorate, perchlorate, bromide, bromate, iodide and iodate. The method was applied for the analysis of drinking water samples collected from water treatment plants in areas in Finland, which are known to have high bromine concentrations in ground water. Water samples collected before and after disinfection were analyzed to get information about potential species conversion as a result of purification. Chloride and chlorate were the chlorine species found in these water samples, and iodine existed as both iodate and iodide. In the case of bromine, species conversion had taken place, since total bromine concentrations were increased during disinfection but bromide concentrations were decreased. No bromate was observed in the samples. The detection limits for all the chlorine species studied were 500 μg/l, for bromine species studied 10 μg/l, for iodide 0.1 μg/l and for iodate 0.2 μg/l.     

Determination of the Dissociation Constants of Urocanic Acid Isomers in Aqueous Solutions

(E)- and (Z)-Urocanic acids are endogenous chemicals in the normal mammalian skin. The first and the second thermodynamic dissociation constants (pK _a1 and pK _a2) of urocanic acid isomers were determined using UV spectrophotometry in aqueous solutions. The values with standard deviation (pK _a1 = 3.43 ± 0.12 and pK _a2 = 5.80 ± 0.04) and (pK _a1 = 2.7 ± 0.3 and pK _a2 = 6.65 ± 0.04) were obtained to (E)- and (Z)-urocanic acids, respectively. The second dissociations were studied also by potentiometric titration in aqueous sodium chloride solutions up to the isotonic salt concentration (0.154 mol dm⁻³), and the second thermodynamic dissociation constants as well as activity parameters for both isomers were determined at temperature 25°C and for (E)-urocanic acid also at 37°C. The obtained pK _a2 values were close to those found by UV spectrophotometry. The equations for the calculation of the second stoichiometric dissociation constants of urocanic acid isomers on molality and molarity scale in aqueous sodium chloride solutions were derived. The obtained pK _a1 and pK _a2 values for (Z)-urocanic acid appear to be essentially lower than some previously reported values in literature.     

A comparative study on the behaviour of 1,3-diheterocyclopentanes (X = O,O; S,S; O,S) under electron impact. The formation of thioacetyl and thiiranyl cations

The electron-impact-induced mass spectra of 1,3-dioxolane (la), 1,3-dithiolane (2a) and 1,3-oxatbiolane (3a) and their 2-methyl (1b–3b) and 2,2-dimethyl [(CH₃)₂: 1c–3c or (CD₃)₂: 1d–3d] derivatives have been studied in detail to gain further insight into their ion structures and competing reaction pathways with low-resolution, high-resolution, metastable and collision-induced dissociation (CID) techniques. For compounds 1a–1d the most significant reaction is loss of H^˙ and CH₃^˙ by α-cleavage and a subsequent formation of CHO⁺ and C₂H₃O⁺ ions. The [M ? H]⁺ ions from 1a and 1b give a C₂H₃O⁺ ion which does not have the acyl cation structure as shown by their CID spectra. In compounds 3a–3d the sulphur-containing ions predominate, the C₂H₃O⁺ now having the acyl cation structure. 1,3-Dithiolanes (2a–2d) exhibit the most complicated fragmentation patterns. Furthermore the [M ? H]⁺ ion from 2a and [M ? CH₃]⁺ ion from 2b have different structures as well as the [M ? H]⁺ ion from 2b and [M ? CH₃]⁺ ion from 2c, as shown by their CID spectra. This can be utilized to explain why 3a–3c and 2a give principally a thiiranyl cation, whereas 2b gives a mixture of this and the thioacyl cation and 2c practically only the open-chain thioacetyl cation.     

Arithmetical identities of the Brauer-Rademacher type

Summary LetA be a regular arithmetical convolution andk a positive integer. LetA _k (r) = {d: d ^k A(r ^k )}, and letf A _k g denote the convolution of arithmetical functionsf andg with respect toA _k . A pair (f, g) of arithmetical functions is calledadmissible if(f A _k g)(m) 0 for allm and if the functions satisfy an arithmetical functional equation which generalizes the Brauer—Rademacher identity. Necessary and sufficient conditions are found for a pair (f, g) of multiplicative functions to be admissible, and it follows that, if(f A _k g)(m) 0 f(m) for allm, then (f, g) is admissible if and only if itsdual pair (f A _k g, g ^–1 ) is admissible.Iff andg ^–1 areA _k -multiplicative (a condition stronger than being multiplicative), and(f A _k g)(m) 0 for allm, then (f, g) is admissible, calledCohen admissible. Its dual pair is calledSubbarao admissible. If (f A _k g) ^–1 (m) 0 itsinverse pair (g ^–1 , f ^–1 ) is also Cohen admissible.Ifg is a multiplicative function then there exists a multiplicative functionf such that the pair (f, g) is admissible if and only if for everyA _k -primitive prime powerp ⁱ either (i)g(p ⁱ ) 0 or (ii)g(p ) = 0 for allp havingA _k -type equal tot. There is a similar kind of characterization of the multiplicative functions which are first components of admissible pairs of multiplicative functions. IfA _k is not the unitary convolution, then there exist multiplicative functionsg which satisfy (i) and are such that neitherg norg ^–1 isA _k -multiplicative: hence there exist admissible pairs of multiplicative functions which are neither Cohen admissible nor Subbarao admissible.An arithmetical functionf is said to be anA _k -totient if there areA _k -multiplicative functionsf _T andf _V such thatf = f _T A _k f _V ^-1 Iff andg areA _k -totients with(f A _k g)(m) 0 for allm, and iff _V = g _T , then the pair (f, g) is admissible. The class of such admissible pairs includes many pairs which are neither Cohen admissible nor Subbarao admissible. If (f, g) is a pair in this class, and iff(m), (f A _k g) ^–1 (m), g ^–1 (m),f ^–1 (m) andg(m) are all nonzero for allm, then its dual, its inverse, the dual of its inverse, the inverse of its dual and the inverse of the dual of its inverse are also admissible, and in many cases these six pairs are distinct.A number of related results, and many examples, are given.     

Die Einheitlichkeit des 2,4-Dinitrophenylosazons des Glyoxals

Zusammenfassung Aus Glyoxal wurden mit salzsaurer 2,4-Dinitrophenylhydrazinlösung Hydrazone dargestellt. Als Ausgangssubstanz kamen das Mono- und Polyglyoxal sowie die Hydrogensulfitverbindung des Glyoxals und dessen Tetraäthylacetal zur Anwendung. Bei Einhaltung einer genügend langen Fällungsdauer erhielt man als Reaktionsprodukt in allen Fällen dieselbe Verbindung, das Osazon des Monoglyoxals, das bei der Reduktion mit Zinn und Salzsäure in 1,2-Diaminoäthan überging. Bei zu kurzer Fällungsdauer wurde als Reaktionsprodukt — unabhängig von der zugegebenen Reagensmenge — ein Gemisch der Mono- und Bishydrazone des Monoglyoxals erhalten. Die Komponenten wurden sowohl papierals auch dünnschichtchromatographisch getrennt. Bei Behandlung mit alkalischem Äthanol wurde das Monohydrazon orange und das Bishydrazon, das Osazon, blau gefärbt. Die von uns früher geäußerte Auffassung^18,19, daß sich das Osazon des Glyoxals mit alkalischem Äthanol blau färbt, erwies sich somit als stichhaltig.

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Summary Hydrazones of glyoxal were prepared from mono- and polyglyoxal, from the bisulfite derivative of glyoxal and the tetraethyl acetal with 2,4-dinitrophenylhydrazine in hydrochloric acid solution. When sufficient time was used for precipitation the same compound, monoglyoxal osazone, was obtained in all cases. Reduction of the monoglyoxal osazone with tin and hydrochloric acid gave diaminoethane. If the precipitation time was too short, a mixture of the mono- and bishydrazones of monoglyoxal was obtained-independently of the amount of reagent added. The components were separated by paper and thin-layer chromatography. The monohydrazone gave an orange colour with alkaline ethanol, while the bishydrazone, osazone, gave a blue one. Thus our previous opinion^18,19 that the osazone of glyoxal gives a blue colour with alkaline ethanol has been confirmed.