N.A. Gibson

The distribution of salts of large cations between water and organic solvents: Part II. Factors affecting the magnitude of the distribution ratio

Abstract The extraction of salts of fourteen different quaternary cations with nineteen different anions into four different solvents was measured. The results obtained are discussed in terms of the effects of the cation, the anion and the organic solvent on the distribution ratio. The extraction is found to depend on the size of the quaternary cation and the solvating properties of the organic solvent. A good correlation is obtained between percentage extraction of the quaternary salt and the enthalpy of hydration of the anion.

An extraction—spectrophotometmc method for the determination of non-ionic surfactants

Abstract The surfactant is extracted into 1,2-dichlorobenzene as a neutral adduct with potassium tetrathiocyanatozincate(II), and zinc(II) in the extract is determined spectrophotometrically after addition of l-(2-pyridylazo)-2-naphthol and triethanolamine. With a 150-ml water sample, the limit of detection is 15 μg l -1 (as Triton X-100). The method requires only one extraction and is applicable, without modification, to fresh, estuarine and sea-water samples.

An atomic absorption spectrometric method for the determination of non-ionic surfactants

A method is described for the determination of non-ionic surfactants in the concentration range 0.05–2 mg l-1.Surfactant molecules are extracted into 1,2-dichlorobenzene as a neutral adduct with potassium tetrathiocyanatozincate(II) and the determination is completed by atomic absorption spectrometry. With a 150-ml water sample, the limit of detection is 0.03 mg l-1(as Triton X-100).The method requires a single phase separation step, is applicable, without modification, to fresh, estuarine and sea-water samples and is relatively free from interference by anionic surfactants; the presence of up to 5 mg l-1 of anionic surfactant (as LAS) introduces an error of no more than 0.07 mg l-1 (as Triton X-100) in the apparent non-ionic surfactant concentration.

The micro-estimation of cobalt with triphenyl-methylarsonium thiocyanate

Abstract Triphenylmethylarsonium thiocyanate is recommended for the colorimetric micro-estimation of cobalt. The procedure is suitable within a range of 10 to 100 mg of cobalt per ml with an accuracy of about 2%. It enables the micro-estimation of cobalt to be carried out on most of its common alloys, no prior separation being required in most cases, and in the others, simple partial separations being sufficient.

Colorimetric determination of palladium with pyridine-2-aldehyde-2'-pyridylhydrazone

Abstract The colorimetric determination of palladium described involves the extraction of chloro(PAP)palladium(II) from an acidic aqueous solution into o-dichlorobenzene and measurement of the absorbance of the extract solution. The method is suitable for the determination of 10–100 μg of palladium. Tolerance amounts for many metals have been determined and compare very favourably with those of other methods.

The determination of anionic detergents at p.p.b. levels by graphite furnace atomic absorption spectrometry

Abstract A method is described for the determination of anionic detergents at levels below 50 μg l -1 . The detergent anions are extracted into chloroform as an ion-association compound with the bis(ethylenediamine)copper(II) cation and determinations are completed by atomic absorption spectrometry with a graphite furnace atomizer. With a 750-ml water sample, the limit of detection is 2 μg l -1 (as linear alkyl sulphonic acids). The method requires a single extraction and is highly selective. It is applicable without modification to fresh, estuarine and sea-water samples.

Extraction-spectrophotometric determination of sulphide and sulphite in waters based on formation of the bis(2,9-dimethyl-1,10-phenanthroline) copper(I) ion

Abstract A spectrophotometric method is described for the determination of sulphide or sulphite. The bis(2,9-dimethyl-1,10-phenanthroline)copper(II) ion is reduced at pH 10 by sulphide in the presence of formaldehyde and by sulphide and sulphite in its absence. The resulting copper(I) complex is extracted into chloroform and measured. With any convenient sample volume between 1 and 100 ml, the limits of detection are 0.1 mg for sulphide and 0.25 μg for sulphite. The method is unaffected by iron(II) and nitrite, in concentrations of 100 and 1000 mg l -1 , respectively.

Metal-pyridine-2-aldehyde-2'-pyridylhydrazone complexes as visual acid-base indicators: Indicator constants, colour changes and titrations

Abstract The PAPHY complexes of certain metals are suggested as acid-base indicators. The colour change intervals of aqueous solutions of the complexes of Cu(II), Fe(II), Ni(II), Zn(II), and Cd(II) have been studied. Apparent indicator constants have been determined. The performance of the indicators in titrations of weak and strong acid and bases is excellent.

Edta titrations with extractive end-points: Determination of cobalt

Abstract A method for the determination of cobalt by the addition of excess EDTA and back-titration with standard cobalt solution is recommended. The titration involves an extractive method of end-point detection, depending upon the appearance of the blue colour of the ion-association pair [Ph 3 MeAs] 2 [Co(SCN) 4 ]in chloroform. The method is therefore suitable for the estimation of cobalt in highly coloured aqueous solutions. Average errors can be expected to be less than 0.5%..

The determination of anionic detergents with the bis (ethylenediamine)copper(II) ion

Abstract A method is described for the determination of anionic detergents. The detergent anions are extracted into chloroform as an ion-association compound with the bis(ethylenediamine)copper(II) cation. Determinations are completed by colorimetry or atomic absorption spectrometry. With a 150-ml water sample, the limit or detection is 0.03 μg ml -1 (as LAS) for colorimetry or 0.06 μg ml -1 for a.a.s. The method requires only one phase separation step and is highly selective. It is directly applicable to brine and sea-water samples.