Disclaimer UWE has obtained warranties from all depositors as to their title in the material deposited and as to their right to deposit such material. UWE makes no representation or warranties of commercial utility, title, or fitness for a particular purpose or any other warranty, express or implied in respect of any material deposited. UWE makes no representation that the use of the materials will not infringe any patent, copyright, trademark or other property or proprietary rights. UWE accepts no liability for any infringement of intellectual property rights in any material deposited but will remove such material from public view pending investigation in the event of an allegation of any such infringement. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 PLEASE SCROLL DOWN FOR TEXT. AbstractRohypnol (flunitrazepam) has been determined by high performance liquid chromatography dual electrode detection (LC-DED), both in the redox mode and the dual reductive mode. Initial studies were performed to optimise the chromatographic conditions and these were found to be 50 % acetonitrile, 50 % 50 mM pH 2.0 phosphate buffer at a flow rate of 0.75 ml/min, employing a Hypersil C18, 5 µm, 250 mm x 4.6 mm column. Cyclic voltammetric studies were made to ascertain the redox behaviour of Rohypnol at a glassy carbon electrode over the pH range 2-12. Hydrodynamic voltammetry was used to optimise the applied potential at the generator and detector cells; these were identified to be -2.4 V and +0.8 V for the redox mode and -2.4 V and -0.1 V for the dual reductive mode respectively. A linear range of 0.5 µg/ml to 100 µg/ml, with a detection limit of 20 ng/ml was obtained for the dual reductive mode. Further studies were then performed to identify the optimum conditions required for the LC-DED determination of Rohypnol in beverage samples. A convenient and rapid method for the determination of Rohypnol in beverage samples was developed using a simple sample pre-treatment procedure. A recovery of 95.5 % was achieved for a sample of white coffee fortified at 9.6 µg/ml Rohypnol.
A method of assay of quaternary ammonium germicides in strong solutions or concentrated solid form is described. It can be used for soIutions down to about 1 per cent in content. A known excess of iodide is added to the sample solution and the quaternary ammonium iodide is removed by shaking with chloroform. The excess iodide is titrated by an iodate method. When the chloroform extraction is made from a slightly alkaline solution only quaternary ammonium compounds are measured; if it is made from a slightly acid solution, non-quaternary cationic amine impurities are also included. The dserence between assay results obtained from acid and alkaline extractions represents the non-quaternary amine content.SEVERAL methods of assay exist for benzalkonium chloride and other similar quaternary ammonium germicides. Some of those designed for very dilute solutions are both convenient and selective, for example, the colorimetric method of Auerbach (1943), and adaptations of the titrimetric method of Barr, Oliver and Stubbings (1948), where solvent extraction is from an alkaline solution.However, few satisfactory methods have been described for strong solutions such as the 50 per cent Benzalkonium Chloride Solution of the B.P.C. 1959, or the solid form of the U.S.P. XVI.The available methods involve precipitation of an insoluble salt or complex, followed by filtration and determination of the excess precipitant, or gravimetric estimation of the precipitate. The precipitants include ferrocyanide (Lottermoser and Steudel, 1938), dichromate (Flotow, 1942), ferricyanide (Wilson, 1946), reineckate (Wilson, 1952, 1954), phosphotungstate (Yoshimura and Morita, 1955Lincoln and Chinnick, 1956), phosphomolybdate and tetraphenylboron (Kirsten, Berggren and Nilsson, 1958). The Danish Pharmacopoeia (1954) adopts precipitation as the iodide in acid solution, then extracts the benzalkonium iodide with chloroform and titrates the separated chloroform solution with acetous perchloric acid. None of these methods distinguish the quaternary ammonium halide from tertiary long-chain alkyl amine hydro-halides which are the most likely organic impurities of the quaternary compound.The ferricyanide method has been the one mostly used, having been the U.S.P. method since 1945. The B.P.C. has adopted a modified version. This method has proved its usefulness, but it is known to suffer from disadvantages. It involves filtration of the gelatinous benzalkonium ferricyanide which needs to stand for 1 hr., and a volume of the filtrate is titrated equivalent to half the volume of the precipitated mixture, thus 379 E. R. BROWN requiring a precipitate-volume correction. The B.P.C. version directs the complete washing of the precipitate free from ferricyanide, followed by titration of the whole of the filtrate. In addition, the end-point of the ferricyanide titration is not sharp and final, and the burette readings are small with the U.S.P. method while the B.P.C. employs a 5 g. sample, necessitating a volume of nearly 1 litre to be titrated to obtain a titrat...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.