Validation of an analytical procedure for the determination of oxidative hair dyes in cosmetic formulations.
A high range and variety of cosmetic formulations that contain oxidative hair dyes and matrix-forming compounds have been industrially developed over recent years and are now available on the international market. Member states of the European Union are responsible for conducting analyses of cosmetic products as deemed necessary by law and European regulation enforcement. Therefore, inspection authorities as well as the cosmetics trade and industry need validated analytical methods for the identification, characterization, and/or quality control of specific active ingredients or formulations with the aim of implementing the European Union Cosmetic Directives (76/768/ECC, 95/17/EC). In this frame, we validated a candidate reference method that enables the identification and quantification of hair dye-forming compounds. This method consists of a separation by RP-HPLC coupled with a DAD after a liquid-liquid extraction procedure for separating matrix components from the dye-forming compounds. The validation of the method includes common criteria such as the repeatability of the analysis and the establishment of figures of merit, as well as statistical evaluations and quality assurance in order to follow the recommendations of the Eurachem guide for analytical measurements.
Influence of Matrix Compounds on the Analysis of Oxidative Hair Dyes by HPLC.
Synopsis Oxidative hair dyeing products consist of a mixture of a broad spectrum of organic compounds including the hair dye's so-called active compounds and the matrix-forming compounds. Forty-seven dye intermediates commonly used in cosmetic formulations have thus been analyzed by RP-HPLC, and their chromatographic characteristics have been recorded. Since the matrix compounds could interfere with the quantitative analysis of the active compounds, eighteen matrix compounds commonly used in cosmetic formulations have been tested for their influence on dye intermediate determination. Since some of them do affect the chromatographic behavior of the dye intermediates, an isolation procedure, for separating matrix components from the dye-forming compounds, consisting of a liquid-liquid extraction by n-heptane, has been set up. In most cases, this procedure is effective for the extraction of the matrix products. Moreover, the dye intermediates are not extracted by n-heptane, and their chromatographic behavior is not altered by the extraction procedure. In summary, this study has shown that a reference method for the analysis of oxidative hair dyes should include a compulsory extraction step before submission of samples to RP-HPLC.
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.