A new reagent for the detection and determination of small amounts of the sulphate Ion

An aqueous solution of 2-aminoperimidine hydrochloride is proposed as a new reagent for the detection and determination of the sulphate ion. As little as 0.05 p.p.m. can be detected by precipitation of the corresponding amine sulphate. Suspensions of the precipitate show remarkable stability and no colloidal stabilizers are needed. The reagent is applied to the nephelometric determination of 0.1–5 p.p.m. of sulphate ion; at the 0.5 p.p.m. level, the relative standard deviation is 4.5%. Although many ions form precipitates with the reagent at high concentrations, very few of the common anions provide significant interference in the nephelometric determination. The reagent seems promising for the determination of sulphate in natural waters, and for traces of sulphur in organic compounds after oxygen flask combustion.     

The spectrochemical determination of total strontium in bone,milk and vegetation

Samples of bone ash are mixed with anhydrous copper sulphate and graphite and pelleted A d c. arc is used to excite the spectra which are then evaluated by microphotometry The effective concentration range is 50 – 350 p p. m of strontium in the ash and the coefficient of variation is 6% for single exposures at the 90 p p m levelIn the case of milk and vegetation, strontium and calcium are separated as insoluble oxalates and the strontium content of this fraction determined by a method similar to that used for bones, with a similar range and accuracy. An alternative flame photometric method is described for the determination of strontium in the calcium-strontium oxalate fraction, thc coefficient of variation of the whole analytical operation being 5% per determination     

Indirect flame photometric determination of sulphate ions

In this paper the possibilities have been studied of determining sulphate ions by indirect flame photometry by difference. Barium and Strontium in constant concentration were used as background elements. By means of the methods proposed sulphate ions can be determinined in the concentration range 0 to 70 p.p.m. with barium and 0 to 110 p.p.m. with strontium. The determinations can be carried out in dilute solutions of alkali metal sulphates and sulphate ions can also be estimated in the presence of macroquantities of other compounds. This may prove useful for the quantitative estimation of sulphate as an impurity in Chemical reagents. Some examples are given of the determination of the degree of purity of substances containing sulphate as impurities.     

Determination of diphenhydramine hydrochloride by flow injection with bromophenol blue and turbidimetric measurement

The study of a number of diphenhydramine-dye systems was carried out in order to determine the most suitable precipitate for the turbidimetric determination of diphenhydramine using flow injection (FI). The reagent selected was Bromophenol Blue. The chemical and FI variables were optimised. The calibration graph was linear over the concentration range 50-230 p.p.m. of diphenhydramine hydrochloride. A number of interfering substances were also investigated.     

Spectrophotometric determination of gold with phenyl-α-pyridyl ketoxime

A method is described for the spectrophotometric determination of gold in the concentration range of 2 to 16 p.p.m. using phenyl-α-pyridyl ketoxime as the reagent. The reagent permits to detect Iμ of gold in I ml of a solution. The method is particularly free from interference by the ions with which gold is frequently associated.     

The application of differential pulse polarography to the determination of a pharmacologically active benzhydrylpiperazine derivative and its major electroactive metabolites in the plasma and urine of animals.

A method for the determination of 1–500 p.p.m. of acid-soluble aluminium and 2–500 p.p.m. of acid-insoluble aluminium in low-alloy and stainless steels by flameless atomic absorption with a HGA 74 graphite furnace is described. A typical value of the relative standard deviation for acid-soluble aluminium at concentrations larger than 10 p.p.m. was 5 %. The steel sample was dissolved in hydrochloric and nitric acid and filtered. Ammonium sulphate was added to the filtered sample in order to overcome interferences caused by hydrochloric acid. No concentration steps were used. Acid-soluble aluminium was determined within 20 min. The influence of iron, chromium, nickel, molybdenum, hydrochloric acid, nitric acid and ammonium sulphate respectively was investigated.     

Spectrophotometric determination of osmium: Sulphanilic acid as a reagent

Sulphanilic acid has been found to be a very effective reagent for the spectrophotometric determination (if hexavalent and octavalent osmium in the pH range between 1.8 – 3.5. In these two valence states, the element forms a dark-violet complex with the reagent, the absorption maximum of the complex being at 490 mμ. As most of the other ions interfere in the determination, the element must be separated as osmic acid by nitric acid distillation. Beer's law is obeyed in the case of 0.5 to 9 p.p.m. of osmium (VIII) and l to 18 p.p.m. of osmium (VI); tin-optimum concentration ranges are from 2 to 8 p.p.m. for osmium(VIII) and from 4 to 16 p.p.m. for osmium(Vl). In these ranges, the % relative errors per 1% absolute photometric error are 3.02 for osmium (VIII) and 3.1 for osmium(VI). Application of the method of continuous variations and the molar ratio method indicates that in solution hexavalent osmium and the reagent form a 1:2. complex, with an average dissociation constant of 1.2 ? 10^-7.     

Spectrophotometric determination of cobalt and nickel with Pyridine-2-Aldehyde-2-Quinolylhydrazone

Pyridine-2-aldehyde-2-quinolylhydrazone (PAQH) is a selective and sensitive reagent for cobalt or nickel. The reagent reacts with only a few metals to give coloured complexes; with the exception of palladium, the cobalt chelate is the only complex relatively stable towards protons and PAQH is a very selective reagent for cobalt. In the presence of thioglycollic acid only nickel reacts with PAQH; the chelate is extracted with chloroform and its absorbance measured at 492 nm. The high molecular extinction coefficients (30·10³ and 51·10³) permit the determination of 0.2–2 p.p.m. of cobalt and 0.1–1 p.p.m. of nickel.     

Determination of Sulphur in Solid and Liquid Samples by Potentiometric Titration with Ion Selective Electrode.

Abstract

This paper describes a potentiometric method for the determination of sulphur in solid and liquid samples, using a sulphide ion selective electrode after the reduction distillation step. The determination of sulphide in solid and liquid samples without prior treatment was carried out by direct and titration potentiometric methods.

The reproducibility of the method and the recovery of sulphate in solid samples was investigated using analytical reagent grade 99% sodium sulphate. Portions of aproximately 100 mg of reagent were subjected to the reduction distillation process. After the ion selective electrode showed a stable value of the potential, indicating that all the sulphate had been reduced to sulphide, the potentiometric titration with lead nitrate solution was performed. A mean recovery of 98% of sulphate was found. The potentiometric titration method described in this work, can be applied to determine S⁼ in solid samples with the advantage that it does not require sample solubilization or extraction prior to the determination. The method yields an almost total reduction of sulphur and also a good precision.     

Some factors influencing the solubilities of amine sulphates

The relationship between the molecular structures of amines and the solubilities of their sulphates has been examined with the object of finding a better reagent than benzidine for the determination of sulphate. It has been established that the two aromatic rings must have a tendency to be coplanar and collinear, if the sulphate solubility is to be low. With the help of this theory, 4 : 4'-diaminotolane sulphate has been found to be less soluble than bcnzidine sulphate.     

Spectrophotometric determination of iron with quinolinic acid

Quinolinic acid forms two complexes with ferrous ion. One is formed at pH 5.9 and has maximum absorption at 420 mμ; the metal to reagent ratio is 1:2 and the instability constant is about 7.10^-9. The other complex is formed with an excess of potassium cyanide and shows maximum absorption at 440 mμ; the metal to reagent ratio is 1:1 the instability constant is only 2.73?10^-5. The latter complex adheres to Beer's law from 1 to 16 p.p.m. of iron, and its optimum concentration range is 4^-16 p.p.m. of iron, where the percent relative error per 1% absolute photometric error is only 2.94.The reagent is highly specific and can be used spectrophotometrically for the determination of very small quantities of iron in presence of many cations.     

4-amino-4'-chlorodiphenyl as analytical reagent for sulphate

The acidic dissociation constant and the solubility of 4-amino-4'-chlorodiphenyl have been determined. The solubility of the amine sulphate has been redetermined and found to be ten times greater than reported earlier. The reason for the discrepancy is revealed, and the use of the amine as a reagent in the micro-analytical determination of sulphate is discussed in the light of the experimental results.     

Tiron as a spectrophotometric reagent for the estimation of osmium

A method for the spectrophotometric determination of osmium with tiron as a reagent has been described. The reagent forms a soluble and stable coloured complex on heating with osmium in the presence of sodium acetate. The regions of maximum and minimum absorptions are at 470 mμ and 410 mμ, respectively, and the system obeys Beer's law from 2 to 32 p.p.m. of osmium. But the optimum range, with the relative analysis error of 2.878% per 1% absolute photometric error, is from 8 to 24 p.p.m. of osmium. The sensitivity of the reaction is 0.033 μg/cm² (SANDELL) and the molar extinction coefficient is 5706. In solution, the complex is formed when the osmium and the reagent are in a ratio of l : 1 ; it has an instability constant equal to approximately 5.57? 10^-5.     

A permeation method for the determination of average concentrations of carbon monoxide in the atmosphere

A simple, inexpensive and reliable method for the determination of average concentrations of carbon monoxide in the atmosphere is described. Silver p-sulfa-moylbenzoic acid is used as the colorimetric reagent in a specially designed permeation device. The calibration graphs are linear up to 80 p.p.m. carbon monoxide, and the limit of detection is 2 p.p.m. for a 24-h exposure. Tests under field conditions are discussed.     

Chelate formation of ammonium aurintricarboxylate with bivalent copper : Micro-determination of copper by the colorimetric method

The formation of a coloured copper II chelate by ammonium aurintricarboxylate with λmax at 540 mμ may be utilised in the colorimetric determination of cupric ions on a micro-scale. It has been found that, for satisfactory results, at least a twentyfold molar excess of the reagent should be added. The colour intensity can be measured by using a spectrophotometer or a photoelectric colorimeter with a suitable filter.The colour is stable at room temperature for sufficiently long periods, but the intensity decreases above 30°C. For the formation of a colour suitable for measurement, the pH should be within 5.3–6.7. The smallest amount of copper that can be detected by the reagent is 1.7 p.p m. Details have been worked out for the use of this reagent, and the interference by various foreign ions has been noted and tolerance limits determined spectrophotometrically.     

5:6-Benzoquinaldinic acid as a colorimetric reagent

5:6-Benzoquinaldinic acid, like α-picolinic acid, has been utilised as a colorimetric reagent for iron (ous). Transmittancy measurements with the Lumetron 402 EF having a cell of capacity 16 ml and thickness 20 mm show that iron from 0.4 to 20 p.p.m. may be estimated, while that with Klett-Summerson photoelectric colorimeter, iron from 5 to 50 p.p.m. may be determined in a tube cell of capacity 15 ml and diam. 12 mm. The optimum range with the minimum error is from 2.4 to 14 p.p.m. The effect of diverse ions, reagent, reducing agent, cyanide and other physical conditions as temperature, time, etc. on the colour system has been investigated.     

The determination of microgram quantities of fluoride : The determination 0f fluoride in waters and sewage effluent using the aluminium-haematoxylin complex

The application of the aluminium-haematoxylin reagent to the determination of fluoride in sea-water, river and potable waters, and sewage effluent is described. It has been shown that down to a level of about 0.1 p.p.m. the fluoride can be determined directly (i.e. without prior separation by distillation); there is some loss in accuracy for amounts of the order of 0.2–0.5 p.p.m. With sea-water, calibra tions should be carried out in a blank of artificial sea-water. The fluoride contents of a number of British rivers etc., are given.     

Determination of Residues of Furadan (Carbafuran) in Water by Spectro-Photometric Method

Abstract

A spectrophotometric method for the determination of carbafuran residues in field water using eerie sulphate as a reagent has been worked out.     

Spectrophotometric determination of osmium with 1-naphthylamine-4,6,8-trisulfonic acid

This investigation was undertaken to determine if the naphthylamine sulfonic acid-osmate (OsVI) reaction is suitable for a spectrophotometric determination of osmium. The 1-naphthylamine- 4, 6,8-trisulfonic acid osmate complex is water-soluble and forms a stable violet-colored system at PH 1 to 1.5 that is independent of reagent concentration. At 555 mμ the colored complex obeys Beer's law over a concentration range of 0.1 to 6.5 p.p.m. osmium and remains stable with respect to time and temperature. The effects of pH, temperature, reagent concentration, and diverse ions were studied. The nature of the organo-osmate complex in solution was studied by three techniques and the effect of temperature and pH on the rate of complex formation was determined. A procedure for the removal of osmium from all interfering ions was developed based on well known distillation techniques.A convenient, sensitive, reproducible and accurate method for the spectrophotometric determination of osmium has been developed.     

Spectrofluorimetric determination of trace amounts of Ga(III) in aluminium and biological samples with 1-(2-pyridylazo)-2-naphthol in sodium dodecyl sulphate micellar medium

Summary A spectrofluorimetric method is proposed for the determination of gallium with 1-(2-pyridylazo)-2-naphthol as derivative reagent in sodium dodecyl sulphate micellar medium. Sensitivity is increased by a factor of 20 with respect to that obtained in 20% ethanol medium. The stoichiometry of the complex is 11. Optimum working conditions are about pH 4, 0.3% sodium dodecyl sulphate and absence of ethanol. The calibration graph is linear in the range 5–400 ppb of Ga(III) with a variation coefficient of 1.5% at 210 ppb of Ga for 10 replicates, and detection limit is 0.8 ppb. Main interferences are from copper and cobalt. Results obtained in the determination of Ga(III) in urine and aluminium samples show the validity of the method proposed.

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Spektrofluorimetrische Bestimmung von Spuren Ga(III) in Aluminium und biologischen Proben mit 1-(2-Pyridylazo)-2-naphthol in micellarem Natriumdodecyl-sulfatmedium