1.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.
2.Association between underweight and taste sensitivity in middle- to old-aged nursing home residents in Sri Lanka: a cross-sectional study.
Fuchida S1, Yamamoto T, Takiguchi T, Kandaudahewa G, Yuyama N, Hirata Y. J Oral Rehabil. 2013 Nov;40(11):854-63. doi: 10.1111/joor.12099. Epub 2013 Sep 20.
Low taste sensitivity may be one factor related to undernutrition, which is a major problem in developing countries. The purpose of this cross-sectional study was to examine the association between underweight, one indicator of undernutrition, and taste sensitivity in middle- to old-aged Sri Lankan nursing home residents. Participants were 946 residents with BMI of <25·0 from 25 nursing homes. Data were obtained on height, weight, taste sensitivity, subjective taste ability, sex, age, ethnicity, number of years in nursing homes, activities of daily living (ADL), frequency of exercise, bowel movements, smoking status, drinking status, current number of chronic diseases, number and kinds of medications used, self-reporting questionnaire 20 (SRQ20), subjective smell ability, number of teeth present, Eichner index and flow rate of saliva. Low sensitivity to bitter taste, being male, old age, low ADL, smoking experience, drinking experience, fewer medications used and no use of medication for hypertension and diabetes were each associated with underweight (P < 0·05).
3.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.
4.A capillary zone electrophoresis method for the assay and quality control of mesembrine in Sceletium tablets.
Patnala S1, Kanfer I. J Pharm Biomed Anal. 2008 Sep 29;48(2):440-6. doi: 10.1016/j.jpba.2008.01.002. Epub 2008 Jan 9.
The Sceletium plant has been reported to contain psychoactive alkaloids, specifically mesembrine, mesembrenone, mesembrenol and other related alkaloids. Sceletium is marketed through health shops and on the internet as dried plant powder and as pharmaceutical dosage forms. The objectives of this research was to develop and validate a capillary zone electrophoresis (CZE) method to identify five alkaloids and quantitatively determine the content of the important alkaloid, mesembrine in Sceletium tablets. Since reference standards of the relevant alkaloids are not commercially available for use in quality control of Sceletium products, it was necessary to isolate and characterize an appropriate analytical marker for use in the assay and additional markers for fingerprinting by CZE. The separation of the relevant alkaloids was carried out by CZE on a 50cm effective length, fused silica capillary tubing (50microm i.d.x360microm o.d.) using 50mM of sodium dihydrogen orthophosphate dihydrate at pH 1.
