Cosmetics, analysis

V-Nitrosodiethanolamine has been found in many complex matrices such as cutting and grinding fluids and cosmetics. Analysis for V-nitrosodiethanolamine is complicated by the matrix and a clean-up technique with derivatization is typically required before quantitation of the analyte to achieve adequate sensitivity and selectivity. Ammonium sulfamate may be added to the sample to prevent the artifactual formation ofV-nitrosamines. Derivatives of V-nitrosodiethanolamine have been prepared by acylation, trifluoroacylation, trimethylsilylation and methylation. The derivatives have been analysed by gas chromatography using flame ionization and mass spectro-metric detectors (Occupational Safety and Health Administration, 1990). 

G. Richard, P. Gataud, J. C. Arnaud, and P. Bore, Qualitative analysis of preservatives using high-performance thin-layer chromatography. In Cosmetic Analysis (P. Bore, ed.), Marcel Dekker, Inc., New York, 1985, p. 157. 

Efficacy and Safety Analytes of Interest in Cosmetics Analysis... 

Sample pretreatment in cosmetic analysis depends on the cosmetic form of the finished products and the analytes to be determined, and the analytical techniques to be used. 

Supercritical fluid extraction (SEE) has a very good field of application in cosmetics analysis as separation treatment before different analytical techniques (e.g., waxes, UV filters, preservatives, or vitamins have been extracted from different cosmetic matrices). 

The number and varied chemical nature of the substances that make up cosmetics ingredients have lead to a great variety of methods for cosmetic analysis. 

The use of modern instrumental techniques has increased over the last few years and a great number of scientific publications using different techniques (Figure 2) can be found in the cosmetic analysis literature. Chromatographic techniques are the most used because they allow the simultaneous determination of a number of components without the need for a laborious cleanup process. 

Figure 2 Percentage distribution of analytical techniques used in cosmetics analysis. (Data obtained from the publications compiled in Analytical Abstracts before November 2003.)...

Electrophoretic techniques, mainly capillary zone electrophoresis (CZE) and also capillary iso-tachophoresis (ITP) or micellar electrokinetic chromatography (MEKC) have been used in cosmetic analysis (e.g., determination of cationic surfactants in toiletries, parabens in different cosmetics, fluoride, and polyphosphates in toothpaste, hair dyes, or acid preservatives in cosmetic lotions). However, their use is less extensive than LC, probably because the... 

Bore P (ed.) (1985) Cosmetic Analysis. Selective Methods and Techniques. NewYork Dekker. 

Cosmetic Analysis Selective Methods and Teohniques, edited by P. Bore Cosmetic Safety A Primer for Cosmetic Scientists, edited by James H. Whittam Oral Hygiene Products and Practice, Morton Pader Antiperspirants and Deodorants, edited by Karl Laden and Carl B. Felger Clinical Safety and Efficacy Testing of Cosmetics, edited by William C. Waggoner Methods for Cutaneous Investigation, edited by Robert L. Rietschel and Thomas S. Spencer... 

The Commission, the Member States and the European Cosmetic Industry, represented by COLIPA (the European Cosmetic, Toiletry and Perfumery Association), worked on these physical/chemical methods of analysis between 1980 and 1996. The first European directive on cosmetic methods of analysis (80/1335/EEC) included analytical methods for only a few substances used in cosmetic products however, it also described aspects related to sampling and sample pre-treatment according the type and physical state of the cosmetic preparation. The number of methods developed for cosmetic analysis has increased in successive directives, and to date, six other directives have been published (82/434/EEC, 83/514/EEC, 85/490/EEC, 93/73/EEC, 95/32/EC, 96/45/EC) of which two have been modified to improve some of the methods (87/143/EEC, 90/207/EEC). The European Commission edited a document (European Commission, 1999) in which all the aforementioned directives are compiled and described. 

Section 2.1 was devoted to official methods for cosmetic analysis. Unfortunately, these official methods do not cover the analytical methods necessary to control ingredients that are prohibited/restricted in cosmetics by different legislations (see Sections 1.1 and 1.2). 

In the particular case of cosmetic analysis (see Figure 2.2.1) the following features must be taken into account (1) cosmetic samples are complexes containing a high number of components (2) for quality control, many analytes have to be determined in the same sample and (3) many samples have to be processed (intra and inter batches). The first two... 

Figure 2.2.1 Cosmetic analysis. Features and most suitable properties of the analytical methods.

A substantial number of research articles can be found in analytical literature about cosmetic analysis in which different analytical procedures are proposed to determine a great many ingredients in cosmetics. Despite this, more research in this field is necessary because the proposed methods are still insufficienL Consequently, researchers in the field of analytical chanistry have to make an effort to extend and modernize the existing methods and develop new analytical methods, which can fulfil the requirements of legislation. Therefore... 

The present section gives an overview of the other analytical procedures for cosmetic analysis proposed by different researchers working on this subject. Only general data are given here. Eor details on the procedures to be used to determine different cosmetic ingredients, readers should refer Chapters 3-8 of this book. 

Figure 2.2.6 Percentages of analytical techniques used in reported methods for cosmetic analysis.

Revised references on cosmetic analysis have been classified into five gronps according to the analytical technique used (Figure 2.2.6), namely, chromatographic and related techniques (such as electrophoresis) (69%), molecular spectroscopy (15%), electrochemical measurements (8%), atomic spectroscopy (5%) and others (3%). 

Other books where procedures for cosmetic analysis are given have already been published. From our point of view, three books are of special interest for readers involved in cosmetic analysis. They are... 

Bore (1985) This book is divided into several chapters where different instrumental techniques in cosmetic analysis are described giving some examples based on interesting analytical procedures developed by the Research Division of L Oreal. 

Mitsui (1997) This is a general book with detailed information on all types of cosmetics, manufacturing, legislation, etc. One of the chapters is devoted to cosmetic analysis, summarizing the different instrumental techniques that are useful in cosmetic analysis and providing interesting examples. 

Bell S. J., 1977, Determination of Colors in Cosmetics, Newburger s Manual of Cosmetic Analysis, 2nd ed., Ed. A. J. Senzel, AOAC, Washington, DC. 

A high number of researchers propose the use of liquid-liquid extraction as a separation step. Sohd-phase extraction (SPE) is also used for instance, organic acids as 18)S-glycyrrhetinic and glycyrrhizinic acids (Andrisano et al, 1993) have been determined in toothpaste by LC and glycolic acid (Scalia, 1998) has been determined in shampoo, day cream and gel by LC, after SPE. Sohd-phase microextraction (SPME) is stiU less used in cosmetic analysis, an example is the determination of toxic contaminants in shampoos by GC (Wala Jerzykiewicz and Szymanowski, 1998). 

---