Über die Bestimmung der Schwefelsäure durch Benzidin

Abstract

KefF:. ~~" $~~~~ 190,.] Friedheim u. Nydegger : Best. der Schwefelsilure durch Benzidin. 3) Es wird eine Benzidinlosnng, deren Wirkungswert gegen H2S04 bekannt ist, im UberschuR zu der Losung des Sulfates gegeben, der Niederschlag abfiltriert und ein aliquoter Teil des Filtrates diazotiert. C,,H,(NH,),, 2HC1 + 2NaN0, = 2N, + C,,H,(OH), + 2NaC1 + 2H,O. Der Stickstoff wird gemessen uud so der Uber-schuR der zugesetzten Benzidinlosung, also auch das zur Umsetzung der Schwefelsaure vcrbrauchte Volumen ermittelt. Die von C o u t u r i e r angefuhrten Resultate stimmen meist mit den auf gewichtsanalytischem Wege erhaltenen, doch kommen auch Uifferenzen bis zu 2,5% vor. Die spatere Entwicklung der maBanalytischen Bestimmungsart IaRt diesem Vorschlag nur noch historische Bedeutung zukommen, doch wird er hier erwahnt, weil er unseres Wissens sonst nicht in die Journalliteratur ubergegangen ist und immerhin Interesse verdient. 4) Berl. Berichte 35, 1587 (1902). 4 ;; H C 8 3 0 2 20 9 , HC,H,O, 6 ,, NaC,H30z + 6Mol.HCl 15 ,, NaCzH30z + 15Mol.HC1 2 .. CUCI" 3 9 HCZH302 1 I

Volumetric Semimicrodetermination of Sulfur in Organic Compounds by Use of Oxygen Bomb

“…Other investigators have hydrolyzed with 1 or 2 A sulfuric or hydrochloric acid (10, IS). Melnick et al (6) showed, however, that the vitamin Bt content of a dried yeast sample hydrolyzed with 2 N sulfuric acid was much lower than the value obtained when 0.055 N acid was used for the hydrolysis. They ascribed this to destruction of an acid-labile substance possessing vitamin B« activity.…”

“…No advantage is gained by allowing precipitation to continue overnight. 6. The precipitate obtained from a sample of semimicro size is too large to be collected in a Fiske filter tube (3,5) or on a filter stick, either of which is quickly clogged by the compacted solid.…”

“…No bromine water or H2O2; 0.1 gram of NH*OH.HCl; blank 0.19 ml. of 0.03 N sodium hydroxide 6. Bromine water (satd.)…”

Direct Titration of Sulfate

“…The benzidine method is probably the best known example of a filtration method. It has been the subject of extensive investigation (16,20,49,84,109) and the concentrations of impurities (16,17,20,37,56,91,105,109), concentrations of reagents (17), temperature and method of titration (31,37,46,57,90,95,105), and the method of filtration and washing (31,95,119) have all been carefully studied.…”

A Rapid Volumetric Method for Determination of Sulfur in Coal and Coke

“…The authors' attention was called by V. K. Krieble to several published accounts on the determination of soluble sulfates by the use of benzidine. The method seems first to have been proposed by Midler (19) and was later modified by Raschig (22), von Knorre (l/¿), and Friedheim and Nydegger (7). Subsequent applications of the benzidine method and modifications included the determination of sulfur in biologic liquids (S, 6, 9, IS, 15, 20, 21), rubber (17), organic 1 The preliminary experiments in this investigation were carried out by the senior author in 1920-21 at The Emerson Laboratories, Springfield, Mass.…”