RESUMO
Twenty more aromatic amines are determined by the diazotization and coupling spectrophotometric technique, with 8-amino-1-hydroxynaphthalene-3,6-disulphonic acid (H-acid) and N-(1-naphthy)ethylenediamine (N-na) as coupling agents. The following are determined by both methods: 2,4-diaminotoluene, 2-aminobenzotrifluoride, 4-benzoxyaniline, 2,4-dimethyl-6-nitroaniline, 4,5-dimethyl-2-nitroaniline, 2-amino-9-fluorenone, naphthionic acid (sodium salt), 3-aminonaphthalene-2, 7-disulphonic acid (monosodium salt), 2-aminonaphthalene-1-sulphonic acid, 4-aminonaphthalene-1-sulphonic acid and 2,4-dibromoaniline. The following are determined only by the N-na method: 5-aminosalicylic acid, 2-amino-4-nitrophenol, 4-amino-2,6-dichlorophenol hydrochloride, 2,5-dimethoxy-aniline, 4-aminothiophenol, 4,4'-diaminodiphenylmethane, 1-naphthylamine, 4,4'-diaminobiphenyl-2,2'-disulphonic acid and 4,4'-diaminostilbine-2,2'-disulphonic acid. The optimum acidities for the different aromatic amines for the N-na method vary considerably. A number of aromatic amines cannot be determined by either method.
RESUMO
Twenty-two aromatic amines are determined by the diazotization-coupling spectrophotometric technique, using 8-amino-1-hydroxynaphthalene-3,6-disulphonic acid (H-acid) and N-(1-naphthyl) ethylenediamine (N-na) as coupling agents. The following are determined by both methods: 2-and 4-ethylaniline, 4-aminobenzonitrile, 3- and 4-aminoacetophenone, 4-aminobenzophenone, 4-iodoaniline, 2,5-dichloroaniline, 4-aminohippuric acid, 2-aminobenzyl alcohol, 3-aminobenzamide, sulphathiazole, 2-, 3- and 4-methoxyaniline and 2,4-, 3,4- and 3,5-dimethylaniline. It is possible to determine 2,3- and 2,5-dimethylaniline only by the H-acid method, but 2,6-dimethylaniline cannot be determined by either method. 2-Aminobenzamide can only be determined by the N-na method. In the application of the H-acid method to the methoxyanilines and dimethylanilines, the colour is developed by adding a large excess of sodium bicarbonate and H-acid. In the application of the N-na method to the ethylanilines, methoxyanilines and 2,4-, 3,4- and 3,5-dimethylanilines, the colour is developed by addition of a large excess of N-na reagent and allowing the solution to stand overnight.
RESUMO
A spectrophotometric procedure is proposed for the determination of trace amounts of aniline by diazotization, coupling with N-(1-naphthyl)ethylenediamine in sodium acetate medium, extraction of the yellow dye with chloroform, and conversion into a reddish purple dye. Two methods are available for the conversion. In the first, the chloroform extract is shaken with hydrochloric acid and the dye is converted and transferred into the aqueous phase. In the other, the chloroform extract is evaporated to dryness and the residue is dissolved in glacial acetic acid. The hydrochloric acid extraction method is the more rapid. The minimum detection limits for the two methods are 0.8 and 0.6 mug/ml respectively. Both methods show satisfactory accuracy and precision.
RESUMO
It is customary in industrial analysis in the determination of phenols by the 4-aminoantipyrine (4-AAP) and ultraviolet-ratio spectrophotometric methods to report the total of phenolic compounds as phenol. A study was therefore made of the behaviour of 36 representative phenolic compounds in the 4-AAP and UV-ratio methods, with and without distillation, to ascertain the apparent recoveries relative to that for phenol. The Fisher phenol analyser was used for the UV-ratio method, which depends upon the bathochromic shift (from about 270 to about 290 nm) usually obtained when the solution of the phenol is made alkaline. The apparent recoveries by the 4-AAP method both with and without distillation varied from 0 to 100%. The apparent recoveries by the UV-ratio method without distillation varied from 0 to 148%, and those with distillation varied from 0 to 110%. Sixteen of the compounds tested without distillation gave less than 10% recovery by the 4-AAP method and eleven gave less than 10% recovery by the UV-ratio method. The results after distillation indicated that several of the compounds did not distil completely.
RESUMO
A spectrophotometric method is proposed for the determination of tetrazene (tetracene) in primers and primer mixes that involves treatment of the tetrazene with resorcinol solution and measurement of the intensity of the yellow colour of the diazo-dye produced. In the application of the method, lead styphnate and barium nitrate are first removed by extraction with ammonium acetate solution and then nitrocellulose and PETN are removed by extraction with acetone. The insoluble matter containing the tetrazene is boiled with resorcinol reagent, the solution filtered, and the absorbance measured at 400 nm. Conditions for optimum colour development are studied and the nature of the reaction is considered.
RESUMO
A semimicro spectrophotometric method using 2,4-xylenol is proposed for the determination of nitroglycerine in propellants. The propellant is extracted with methylene chloride, the extract is diluted, and a 10-ml aliquot is evaporated just to dryness. Then 2,4-xylenol reagent and 63% v/v sulphuric acid are added to hydrolyse the nitroglycerine to nitrate and form 6-nitro-2,4-xylenol which is steam-distilled in a Parnas-Wagner Kjeldahl distillation apparatus into a water-ammonia-isopropyl alcohol mixture. The absorbance of the yellow solution of the anion of the 6-nitro-2,4-xylenol is measured. The calibration curve is prepared from potassium nitrate and an empirical factor (5.50) is used to convert from nitrogen content to nitroglycerine (the theoretical factor is 5.40). The 2,4-xylenol should be added before the sulphuric acid in order to prevent interference from diphenylamine and ethyl centralite. The method is designed for the usual nitrocellulose double-base propellants containing 8-50% of nitroglycerine.
RESUMO
An improved method is proposed for the determination of silica, magnesium oxide, R(2)O(3), ferric oxide, calcium oxide, and aluminium oxide in high-purity talc. In the method for silica and magnesium oxide, the sample is fused with sodium carbonate and the cooled melt is dissolved with perchloric acid in such a manner that it floats free from the crucible (in previous schemes for the analysis of talc there are frequently mechanical losses due to the difficulty of removing the magnesium silicate melt from the crucible). The solution is then evaporated to fumes of perchloric acid and the silica is filtered off and ignited. The magnesium oxide is determined in the filtrate by precipitation as magnesium ammonium phosphate and a correction is made for the calcium which is precipitated along with the magnesium ammonium phosphate. R(2)O(3) is determined after treatment of the sample with nitric and hydrofluoric acids and evaporation to fumes of perchloric acid. Iron oxide and calcium oxide are determined by atomic absorption, after treatment with nitric and hydrofluoric acids and evaporation to fumes of perchloric acid. Al(2)O(3) is calculated by difference.
RESUMO
A method is proposed for the determination of barium and strontium peroxides (active oxygen) in igniters in small-arms tracer ammunition. The sample is treated with dilute hydrochloric acid (1 + 9) which dissolves the magnesium powder almost instantaneously and then dissolves the barium or strontium peroxides within 10-30 min. The solution is then filtered to remove the organic substances (calcium resinate, "Parlon". Toluidine Red toner, and zinc stearate) and the peroxide is determined by means of the colour of the titanium-peroxide complex. It is shown that igniter mixes and igniters used in small-arms tracer ammunition deteriorate on storage.
RESUMO
Methods are proposed for the determination of soluble styphnate and nitrate in waste-water from lead styphnate primer plants. The styphnate is extracted from the waste-water with methylene chloride and is determined by measurement of the absorbance of the methylene chloride solution at 273 nm. The nitrate is determined in the aqueous solution left after the methylene extraction by measurement of the absorbance at 220 nm. For complete extraction of the styphnate by the methylene chloride, the solution must be moderately acidic (about 6% perchloric acid). The acidity for the determination of the nitrate is not critical. Before the determination of the nitrate in the aqueous extract, it is necessary to boil the solution to eliminate residual methylene chloride which would interfere with the determination of nitrate. PETN is extracted by the methylene chloride but does not interfere with the determination of the styphnate, since it shows no interfering peaks. Chloride, sulphate, phosphate, fluoride and carbonate do not interfere with the determination of styphnate or nitrate.
RESUMO
An accurate spectrophotometric method is proposed for the determination of pentaerythritol tetranitrate (PETN) in waste water from lead styphnate primer plants by use of phenoldisulphonic acid. The waste water is filtered through a sintered glass crucible and the PETN is determined in the filtrate and the residue. In the determination of PETN in the filtrate, sodium hydroxide is added and the PETN is extracted with methylene chloride (in alkaline solution, styphnate and TNT are not extracted). The methylene chloride solution is then evaporated to dryness, the residue is treated with a solution of phenoldisulphonic acid in sulphuric acid, water and ammonia are added, and the yellow colour is measured. In the determination of PETN in the residue, the PETN is dissolved in acetone, an aliquot of the acetone solution is treated with water and sodium hydroxide, the PETN is extracted with methylene chloride and the colour is developed as above. Various factors affecting the determination were investigated. The solubility of PETN in water was studied.
RESUMO
An accurate method is proposed for the determination of lithium stearate in sebacate-based lubricants. The sample is treated with dilute hydrochloric acid and an extraction is performed with ethyl ether to remove di-isopropyl phosphite which would otherwise interfere by causing the subsequent precipitation of lithium phosphate or lithium metaphosphate. The aqueous extract is then evaporated to fuming with perchloric acid and the lithium is determined by atomic absorption.
RESUMO
The infrared procedure for the determination of nitrogen in raw nitrocellulose has been improved. In the original method 0.31-0.32 g of sample was dissolved in 45 ml of tetrahydrofuran, the solution was weighed, and the infrared peak at 6.0 microm was measured. The calibration curve was prepared by plotting absorbance against mg of nitrogen per g of solution. The method has the disadvantage that the height of the peak is affected by the sample weight. In the improved method the error due to the sample weight is eliminated by using 0.3000 g of sample and diluting to 50 ml in a volumetric flask. The calibration curve is prepared by plotting absorbance against % nitrogen. The method was extended to the semimicro scale by using a 30.0-mg sample and diluting to 5 ml in a volumetric flask. The method has been applied on the macro and semimicro scales to the direct determination of nitrogen in nitrocellulose after a methylene chloride extraction. The amounts of graphite and inorganic salts found in nitrocellulose-base propellants do not interfere, but a correction must be made to refer the results to 0.3000 g of nitrocellulose for the macro method or 30.0 mg of nitrocellulose for the semimicro method. The same calibration curve is used for all procedures.
RESUMO
An accurate spectrophotometric method is proposed for the determination of calcium in zirconium powder by use of murexide. A 0.4-g sample is dissolved in hydrofluoric and sulphuric acids, the solution evaporated to fumes of sulphuric acid, and a mercury cathode electrolysis made if more than 0.05% copper or nickel is present. Ammoniacal precipitation in the presence of ammonium chloride separates zirconium and other elements and an aliquot of filtrate is collected, equivalent to 0.2 g of sample. The ammonium salts are destroyed with nitric and hydrochloric acids and the calcium is determined with murexide. The high reagent blank is shown to be due to the reagent grade nitric acid, hydrochloric acid, and ammonium hydroxide.
RESUMO
Methods are proposed for the infrared determination of barium, strontium, sodium and potassium sulphates by the pellet technique. The semimicro sample is mixed with 300 mg of potassium bromide, the pellet is formed, and the peak heights are determined at the appropriate peak. Barium and strontium sulphates are measured at 983 and 993 cm(-1), respectively. Sodium and potassium sulphates are both measured at 619 cm(-1). Barium and strontium sulphates can be determined in the presence of each other in ratios from 1:20 to 20:1 from the measurements at 983 and 993 cm(-1). Carbonates or nitrates do not interfere with any of the procedures.
RESUMO
A method is proposed for the infrared determination of calcium or lithium in the presence of strontium or barium. A mixture of the nitrates is treated with acetone which dissolves only the calcium or lithium nitrate. The strontium or barium nitrate is filtered off. The nitrate is evaporated to about 2 ml with a stream of dry air and then diluted to 5 ml with acetone. The infrared spectrum is scanned from 860 to 800 cm(-1) and the nitrate peak at 824 cm(-1) for calcium and 827 cm(-1) for lithium is measured. The recommended range is 1-80 mg of calcium or lithium nitrate in the presence of up to about 200 mg of strontium or barium nitrate.
RESUMO
A spectrophotometric method is proposed for the determination of Channel Black in small arms propellants. The Channel Black is separated from the nitrocellulose and other organic compounds by dissolution of the propellant in morpholine and filtration through a sintered porcelain crucible containing an asbestos mat. The Channel Black is then dissolved by treating the mat and crucible with boiling nitric acid for 3 hr, the solution is filtered, and the yellow colour is measured. The colour is due to polycarboxylic acids with cyclic nuclei. The range of the method is from 0 to 0.5% of Channel Black.
