1.[Alkalimetric titrations of salts of organic bases in the Pharmacopoeia].
Bezáková Z, Stankovičová M. Ceska Slov Farm. 2013 Dec;62(6):264-9.
Modified methods - alkalimetry in ethanol 70% with a defined small volume of hydrochloric acid 0.01 mol/l added to the solution of the sample before the titration and alkalimetry in ethanol 70% or ethanol 96% alone with potentiometric end-point detection for the assay of halide salts of 11 organic N-bases has been investigated. The results were compared to those obtained by the method of the European Pharmacopoeia 7th Ed. (Ph. Eur. 7th Ed.). The Ph. Eur. 7th Ed. use for 8 investigated substances alkalimetry in alcohol 96 % with a defined small volume of hydrochloric acid 0.01 mol/l (5 ml) with potentiometric end-point detection: Cinchocaine hydrochloride, Codeine hydrochloride dihydrate, Ethylmorphine hydrochloride, Lidocaine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride, Quinine hydrochloride, Tetracaine hydrochloride. Our results revealed that the Ph. Eur. 7th Ed. method did not work for 5 drugs from this group: Cinchocaine hydrochloride, Ethylmorphine hydrochloride, Papaverine hydrochloride, Pilocarpine hydrochloride and Tetracaine hydrochloride.
2.Comparison of methods and achievable uncertainties for the relative and absolute measurement of photoluminescence quantum yields.
Würth C1, Grabolle M, Pauli J, Spieles M, Resch-Genger U. Anal Chem. 2011 May 1;83(9):3431-9. doi: 10.1021/ac2000303. Epub 2011 Apr 7.
The photoluminescence quantum yield (Φ(f)) that presents a direct measure for the efficiency of the conversion of absorbed photons into emitted photons is one of the spectroscopic key parameters of functional fluorophores. It determines the suitability of such materials for applications in, for example, (bio)analysis, biosensing, and fluorescence imaging as well as as active components in optical devices. The reborn interest in accurate Φ(f) measurements in conjunction with the controversial reliability of reported Φ(f) values of many common organic dyes encouraged us to compare two relative and one absolute fluorometric method for the determination of the fluorescence quantum yields of quinine sulfate dihydrate, coumarin 153, fluorescein, rhodamine 6G, and rhodamine 101. The relative methods include the use of a chain of Φ(f) transfer standards consisting of several "standard dye" versus "reference dye" pairs linked to a golden Φ(f) standard that covers the ultraviolet and visible spectral region, and the use of different excitation wavelengths for standard and sample, respectively.
3.Evaluation of a commercial integrating sphere setup for the determination of absolute photoluminescence quantum yields of dilute dye solutions.
Würth C1, Lochmann C, Spieles M, Pauli J, Hoffmann K, Schüttrigkeit T, Franzl T, Resch-Genger U. Appl Spectrosc. 2010 Jul;64(7):733-41. doi: 10.1366/000370210791666390.
The commercial availability of stand-alone setups for the determination of absolute photoluminescence quantum yields (Phi(f)) in conjunction with the increasing use of integrating sphere accessories for spectrofluorometers is expected to have a considerable influence not only on the characterization of chromophore systems for use in optical and opto-electronic devices, but also on the determination of this key parameter for (bio)analytically relevant dyes and functional luminophores. Despite the huge potential of systems measuring absolute Phi(f) values and the renewed interest in dependable data, evaluated protocols for even the most elementary case, the determination of the fluorescence quantum yield of transparent dilute solutions of small organic dyes with integrating sphere methods, are still missing. This encouraged us to evaluate the performance and sources of uncertainty of a simple commercial integrating sphere setup with dilute solutions of two of the best characterized fluorescence quantum yield standards, quinine sulfate dihydrate and rhodamine 101, strongly differing in spectral overlap between absorption and emission.
4.Development of a model for robust and exploratory analysis of the rodent brief-access taste aversion data.
Soto J1, Sheng Y1, Standing JF1, Orlu Gul M1, Tuleu C2. Eur J Pharm Biopharm. 2015 Apr;91:47-51. doi: 10.1016/j.ejpb.2015.01.016. Epub 2015 Jan 22.
The rodent brief-access taste aversion (BATA) model is an efficient in vivo screening tool for taste assessment. A new E(max) (maximum effect attributable to the drug) model was developed and further investigated in comparison with three previously published models for analysing the rodent BATA data; the robustness of all the models was discussed. The rodent BATA data were obtained from a series of experiments conducted with a bitter reference compound, quinine hydrochloride dihydrate (QHD). A new E(max) model that could be applied to both "lick numbers" and "lick ratios" was built and three published models that used lick ratios were employed for analysing the BATA data. IC50, the concentration that inhibits 50% of the maximum lick numbers, quantified the oral aversiveness of QHD. One thousand bootstrap datasets were generated from the original data. All models were applied to estimate the confidence intervals of the IC50s without symmetric assumption.
