Clinical observations have shown that an intact posterior capsule between aqueous and vitreous may function as a barrier to low and high molecular weight substances, e.g., prostaglandins or the angiogenic factor. To determine if this protective barrier breaks down after posterior capsulotomy, we examined the distribution of fluorescein in human eyes after intracapsular cataract extraction (ICCE), extracapsular cataract extraction (ECCE) and intraocular lens (IOL) implantation with capsulotomy, and ECCE and IOL implantation without capsulotomy in 12 patients each. After ICCE and after ECCE and IOL implantation with capsulotomy, diffusion of fluorescein into the vitreous showed similar values. These values were significantly higher than those obtained in patients after ECCE or ECCE and IOL implantation without capsulotomy. This leads us to believe that an intact posterior capsule prevents the diffusion of soluble substances.

In random autopsies chromium (n = 23) and nickel (n = 16) together with various other metals, were determined in lung tissue by means of flameless atomic absorption spectrometry. With increasing age a significant increase in concentration of both chromium and nickel was found. This is evaluated as an indicator for a corresponding exposure, which is marked by a local (workplace) and regional (environment) share of a clear increase in the total chromium/nickel load and by a life-long duration. The question arises, whether the selective concentration (long half-life) of the inhaled chromium and nickel particles/compounds in the lung are to be regarded as a stochastic lung cancer risk.

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Under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a key comparison, CCQM K55.c, was coordinated by the Bureau International des Poids et Mesures (BIPM) in 2012. Twenty National Measurement Institutes or Designated Institutes and the BIPM participated. Participants were required to assign the mass fraction of valine present as the main component in the comparison sample for CCQM-K55.c. The comparison samples were prepared from analytical grade L-valine purchased from a commercial supplier and used as provided without further treatment or purification.Valine was selected to be representative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of low structural complexity [molecular weight range 100–300] and high polarity (pKOW > −2).The KCRV for the valine content of the material was 992.0 mg/g with a combined standard uncertainty of 0.3 mg/g. The key comparison reference value (KCRV) was assigned by combination of KCRVs assigned from participant results for each orthogonal impurity class. The relative expanded uncertainties reported by laboratories having results consistent with the KCRV ranged from 1 mg/g to 6 mg/g when using mass balance based approaches alone, 2 mg/g to 7 mg/g using quantitative 1H NMR (qNMR) based approaches and from 1 mg/g to 2.5 mg/g when a result obtained by a mass balance method was combined with a separate qNMR result.The material provided several analytical challenges. In addition to the need to identify and quantify various related amino acid impurities including leucine, isoleucine, alanine and α-amino butyrate, care was required to select appropriate conditions for performing Karl Fischer titration assay for water content to avoid bias due to in situ formation of water by self-condensation under the assay conditions. It also proved to be a challenging compound for purity assignment by qNMR techniques.There was overall excellent agreement between participants in the identification and the quantification of the total and individual related structure impurities, water content, residual solvent and total non-volatile content of the sample. Appropriate technical justifications were developed to rationalise observed discrepancies in the limited cases where methodology differences led to inconsistent results.The comparison demonstrated that to perform a qNMR purity assignment the selection of appropriate parameters and an understanding of their potential influence on the assigned value is critical for reliable implementation of the method, particularly when one or more of the peaks to be quantified consist of complex multiplet signals.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIP...