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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An analytical procedure is described for the separation of mercury(II) by extraction into n-octanol from sulphuric acid solution and then back-extraction as the tetraiodo complex. The mercury is determined by measuring the absorbance of this complex at 322 nm (molar absorptivity 1.95 x 10(3) l.mole(-1).cm(-1)). The procedure is applicable to samples containing copper; the effects of a wide variety of other impurities are tabulated.
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PMID:Rapid separation and determination of mercury. 1896 Oct 39

Xylenol Orange and mercury(II) react in the presence of various bases, such as hexamine, pyridine and ammonia, to form ternary complexes, which conform to Beer's law. The 1:1:1 Hg(II)/XO/ base complex at pH 6.1 has an absorption maximum at 590 nm and a molar absorptivity of 2.2 x 10(5) l.mole(-1).cm(-1). In the absence of the base the Hg(II)(XO)(2) complex at pH 7.5 and 580 nm has a molar absorptivity of 1.7 x 10(5) l.mole(-1).cm(-1). Interferences are discussed.
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PMID:Reaction of mercury(II) and xylenol orange-III: determination of microamounts of mercury. 1896 73

A simple, selective and accurate method has been described for the rapid micro and submicro determination of organic nitrates and nitramines. It is based on reaction with mercury-sulphuric acid mixture for 5 min at room temperature followed by potentiometric titration of the mercurous ions released, a solid-state iodide-sensitive electrode being used. Three equivalents of potassium iodide as titrant are consumed per mole of nitrate or nitramine group. The results obtained, with sample sizes ranging from 1.0 to 50 mumole, are precise to +/- 0.2% and the average recovery is 99%. None of the other nitrogenous functional groups responds to this reaction.
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PMID:Ion-selective electrodes in organic functional group analysis: microdetermination of nitrates and nitramines with use of the iodide electrode. 1896 74

A d.c. polarographic technique has been developed which allows measurement of the concentration of calcium ions in aqueous solutions. By applying a potential scan at a rate of 25 mV/sec to a 1.5 sec/drop dropping mercury electrode, peak-shaped waves are obtained for calcium at mM concentrations in tetrabutylammonium hydroxide supporting electrolyte. The square root of the peak height is directly proportional to the calcium concentration over the range 0.1-1.0 x 10(-3)M. In the presence of the sequestrants ethylenediaminetetra-acetic acid (EDTA), nitrilotriacetic acid (NTA) and tripolyphosphate (TP), indications of distinct calcium complexes were seen by noting the positions of slope changes in plots of peak height vs. mole ratio of calcium to sequestrant. The species found were CaEDTA, Ca(3)(NTA)(2), Ca(2)(TP)(3) and Ca(3)TP. All of these are readily acceptable complexes at the high pH of the experimental conditions.
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PMID:Calcium complexes determined by polarography. 1896 34

The system Hg(II)/Xylenol Orange/Amberlite LA-2 dissolved in 1:1 v v 3-methylbutan-1-ol/chloroform medium has been studied. A 3:2:2 complex is formed, which is suitable for analytical measurements at temperatures <18 degrees . This complex allows the determination of mercury in the range 0.19-5.5 ppm with a molar absorptivity of 2.12 x 10(4).mole(-1).cm(-1) at 600 nm and extraction pH of 7.4 (standard deviation 0.065 ppm). The proposed method has been applied to the determination of mercury in contaminated water with a high chloride content.
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PMID:Determination of mercury in the presence of chloride by means of the ternary complex Hg(II)/xylenol orange/amberlite La-2 in non-aqueous media. 1896 42

Mercury(II) reacts with benzyl 2-pyridylketone 2-quinolylhydrazone (BPKQH) in the pH range 9.0-10.4, to form a stable 1:2 (metal:ligand) complex which has a sharp absorption maximum at 475 nm and molar absorptivity 5.01 x 10(4) 1.mole(-1).cm(-1). It is proposed for use in spectrophotometric determination of mercury at microg/ml levels and analysis for organomercurials. The sensitivity of the method can be increased significantly by employing derivative spectrophotometry, making mercury determination at ng ml levels feasible.
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PMID:Spectrophotometric and second-derivative spectrophotometric determination of mercury in organomercurials by means of benzyl 2-pyridyl ketone 2-quinolylhydrazone. 1896 93

N,N'-Bis(2-hydroxy-5-nitrobenzyl)cryptand-22 (22-Koshland) forms yellow complexes with bivalent metal ions, and these are extractable into 1,2-dichloroethane. The overall extraction constants have been estimated for lead (10(-5.4)), copper (10(-5.6)), mercury (10(-5.8)) and cadmium (10(-8.4)). The result obtained has been applied to extraction and photometric determination of lead. The molar absorptivity at the absorption maximum (406 nm) is 4.47 x 10(4) l.mole(-1).cm(-1). The interferences from copper and mercury can be eliminated by the addition of sodium thiosulphate and the interference from cadmium can be eliminated by calculation from the absorbances at 406 and 391 nm (the cadmium complex with 22-Koshland has its absorption maximum at 391 nm). The method has been successfully applied to the determination of lead in zinc powder.
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PMID:Extraction and photometric determination of lead with diazacrown ether dye. 1896 12

1-(4-Nitrophenyl)-3-(2-quinolyl)triazene has been synthesized, and used as an extremely sensitive reagent for the spectrophotometric determination of mercury by the decrease in the absorbance of the reagent at 490 nm and pH 9.0-10.8 in the presence of cetylpyridinium bromide. Beer's law is obeyed over the range 0-120 ng/ml Hg(II), the apparent molar absorptivity being 1.0 x 10(6) l.mole(-1).cm(-1). The effect of 69 ionic species or compounds has been examined. Trace mercury in waste water has been determined satisfactorily.
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PMID:1-(4-nitrophenyl)-3-(2-quinolyl) triazene as an extremely sensitive reagent for spectrophotometric determination of mercury. 1896 48

The formation of the acidocomplex of mercury(II) with triphenyl-tetrazolium chloride is studied spectrophotometrically in water-organic media. The composition of the complex is established as TTC:Hg:I = 1:1:1. The molar absorptivity (255) = (6.45 +/- 0.12) x 10(4) 1 mole(-1). cm(-1) is determined. The selectivity of the reaction is studied and the method for determination of mercury(II) 0.1-0.8 mug/ml is shown. Extraction investigations of the system discussed were carried out. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase was determined: extraction constant K(ex) = 3.16 x 10(4), distribution constant K(D) = 20.67, and association constant = 1.53 x 10(3). 5 A rapid and sensitive extractive-photometric method for determination of mercury(II) in soil was developed. The determination was carried out without preliminary elimination of mercury.
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PMID:Spectrophotometric determination of mercury in soils with triphenyltetrazolium chloride. 1896 93

To investigate the roles of different sulfur (S) species in controlling the partitioning and bioavailability of inorganic mercury (Hg) in anoxic sediments, we examined the differential binding of Hg with three key S species in anoxic sediment (mackinawite [FeS], pyrite [FeS2], and S(2-)) and then quantified their extraction by the gut juice of deposit-feeding sipunculans Sipunculus nudus. A sequential extraction method was simultaneously used to distinguish Hg sorption with different sediment components. All three S-containing sediment components could lead to a high binding of Hg in sediments, but most Hg was sorbed with FeS or FeS2 instead of formation of Hg sulfide despite the presence of S(2-) or humic acid. The gut juice extraction was relatively low and constant whenever FeS and FeS2 were in the sediment, indicating that both FeS and FeS2 controlled the Hg gut juice extraction and thus bioavailability. Mercury sorbed with FeS2 had higher gut juice extraction than that with FeS, while Hg sulfide was not extracted, strongly suggesting that Hg sorbed with FeS2 was more bioavailable than that with other S species. Mercury sorbed with FeS had very low bioavailability to sipunculans at a low Hg:S ratio in the sediment but was more bioavailable with increasing Hg:S ratio up to a maximum (approximately 1:10, mole based). The present study showed that different S species (FeS, FeS2) and Hg:S ratios significantly affected the binding and bioavailability of Hg in anoxic sediments.
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PMID:Inorganic mercury binding with different sulfur species in anoxic sediments and their gut juice extractions. 1936 77


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