Solvent extraction of permanganates (Na, K) by 18-crown-6 ether from water into 1,2-dichloroethane: elucidation of an extraction equilibrium based on component equilibria.
Ion-pair formation constants (K(MLA) mol(-1) dm(3)) of Na(+)- and K(+)-18-crown-6 ether (18C6) complexes with MnO(4)(-) in water (w) were determined potentiometrically at 25 degrees C. Simultaneously, extraction constants (K(ex) mol(-2) dm(6)) of the permanganates with 18C6 from w into 1,2-dichloroethane at 25 degrees C were obtained from the spectrophotometric determination of distribution ratios of the permanganates. These K(ex) values were divided into K(MLA) and other three component equilibrium constants and thereby extraction-selectivity and -ability were discussed in comparison with corresponding metal picrate-18C6 extraction systems reported before.
Solvent Extraction of Sodium Permanganate by Mono-benzo 3 m-Crown-m Ethers ( m = 5 , 6 ) into 1 , 2-Dichloroethane and Nitrobenzene : a Method which Analyzes the Extraction System with the Polar Diluents
Analytical equations were derived for the extraction of univalent metal salts (MA) by crown ethers (L) into polar diluents. Then, NaMnO4 was extracted at 25 C by benzo-15-crown-5 and -18-crown-6 ethers (B15C5 and B18C6) from a water (w)-phase into a 1,2-dichloroethane (DCE)-one. So, the extraction constants of Kex1 and Kex2 were determined, where Kex1 = [NaLMnO4]DCE/[Na][L]DCE[MnO4] and Kex2 = [NaL]DCE[MnO4]DCE/[Na][L]DCE[MnO4] (= Kex1/KNaLMnO4). From the calculation processes of these Kex values, KD,MnO4 and KMLA values with MLA = NaLMnO4 were obtained and also KNaL values were estimated from the thermodynamic cycle of KML = Kex2/KD,MKD,A. Here, the KMLA, KD,A or KD,M, and KML values denote an ion-pair formation constant of MLA in the DCE-phase, a distribution constant of A or M between the wand DCE-phases, and a complex formation one of a complex ion ML in the DCE-phase, respectively. The same values were obtained for the w/nitrobenzene (NB) extraction systems. By comparing the KNaL and KD,NaL (= [NaL]NB/[NaL]: distribution constant into NB) values with those previously-reported by other methods, the validity of the equations was confirmed. Additionally, extraction-abilities of the extraction systems with DCE and NB were examined, using component equilibrium constants reported before.
Community refinement of glaucoma referrals
AbstractAim To describe a Manchester-based glaucoma referral refinement scheme designed to reduce the number of false-positive referrals to the hospital eye service. To report on the first years results of this scheme and its financial costs to the NHS.Methods Patients with suspected glaucoma, instead of being referred to their GP and then on to the hospital eye service, were referred to a group of specially trained community optometrists working to an agreed set of referral criteria. Those patients who did not meet the referral criteria were returned to the referring optometrist, while those who met the referral criteria were referred directly to Manchester Royal Eye Hospital. The patient's GP was informed in all cases.Results The number of suspect glaucoma cases referred to the Manchester Royal Eye Hospital was reduced by 40%. This figure is close to the percentage of false-positive referrals measured at Manchester Royal Eye Hospital prior to the onset of this study. The information accompanying referral has been improved and the scheme produces a small financial cost saving to the NHS of approximately £17 per patient.Conclusion Community refinement of suspect glaucoma offers some important benefits over the current referral pathway.