Comprehensive two-dimensional gas chromatography in combination with rapid scanning quadrupole mass spectrometry in perfume analysis

https://doi.org/10.1016/j.chroma.2004.09.040Get rights and content

Abstract

Single column gas chromatography (GC) in combination with a flame ionization detector (FID) and/or a mass spectrometer is routinely employed in the determination of perfume profiles. The latter are to be considered medium to highly complex matrices and, as such, can only be partially separated even on long capillaries. Inevitably, several monodimensional peaks are the result of two or more overlapping components, often hindering reliable identification and quantitation. The present investigation is based on the use of a comprehensive GC (GC × GC) method, in vacuum outlet conditions, for the near to complete resolution of a complex perfume sample. A rapid scanning quadrupole mass spectrometry (qMS) system, employed for the assignment of GC × GC peaks, supplied high quality mass spectra. The validity of the three-dimensional (3D) GC × GC–qMS application was measured and compared to that of GC–qMS analysis on the same matrix. Peak identification, in all applications, was achieved through MS spectra library matching and the interactive use of linear retention indices (LRI).

Introduction

Perfumes have been applied to human skin for thousands of years and are, today, characterized by a global social and economical importance. Hence, the improvement and development of analytical techniques is considered of the upmost importance by the perfume industries. These complex matrices are characterized by a wide variety of natural and synthetic components belonging to several chemical classes [1]. It must be emphasized that, in the recent years, the risk of contact allergy, induced by perfumery ingredients, has been the object of scientific debate [2]. Under the current European legislation (7th Amendment of the Cosmetic Directive), the 26 most frequently recognized contact allergens (identified by the Scientific Committee on Cosmetics and Non-Food Products Intended for Consumers) must be labeled, by 11 September, 2004, on the final cosmetic product if specific quantities are exceeded.

Monodimensional gas chromatography (GC)-flame ionization detection (FID) and GC–MS are commonly employed in the analysis of major and minor (comprehending suspected allergens) perfume components. It must be added that the determination of trace-level components in fragrances is highly important as these can have a considerable olfactive and economical impact [1], [3]. A series of single column GC methods have been described [4], [5], [6]. Unfortunately, the monodimensional approach often results inadequate in the analysis of the more complex perfume samples, with extensive co-elutions occurring both on apolar and polar stationary phases. The identification of unresolved compounds, when employing MS detection, can be achieved through the support of deconvolution techniques [7], [8], [9], [10]. It is obvious, though, that especially in the case of severely overcrowded chromatograms, the attainment of an improved GC separation and, thus, of high quality analyte mass spectra is always desirable. Furthermore, deconvoluted profiles cannot be obtained for analytes that have very similar ionization patterns.

An enormous increase in resolving power, in respect to monodimensional GC, is the main characteristic of comprehensive GC. The principles of GC × GC have been described thoroughly in literature [11], [12]. The unprecedented resolving power of this method as well as a greater detection sensitivity are ideal characteristics both for complex sample and trace-level analysis.

A GC × GC–FID technique, based on the use of an apolar–polar column set, was employed in the quantitation of five target allergens added to a complex perfume [13]. The quantitation of three out of five allergens was achieved, while nearly 500 peaks were counted on the contour plot.

The hyphenation of a MS detector to a comprehensive GC set-up provides a third analytical dimension. The employment of time-of-flight (TOF–MS) and quadrupole instrumentation has been reported. TOF–MS systems can easily achieve the required spectra acquisition rates (50–100 Hz) for reliable GC × GC peak assignment and quantitation [14], [15], [16]. Unfortunately, the high cost of such instrumentation is the main reason behind its limited laboratory diffusion.

The quadrupole mass spectrometry (qMS), on the contrary, has a relatively low cost and is widely employed in hyphenated GC [7]. It is characterized by high sensitivity but lacks the TOF–MS performance, in terms of detection capabilities. Although this aspect hinders the attainment of reliable GC × GC–qMS quantitative data, precious qualitative information can be obtained [17], [18], [19], [20]. In Refs. [18], [19], the use of a wider-bore secondary capillary, under the low qMS pressure conditions, enhanced the two-dimensional (2D) column efficiency. A further GC × GC–qMS research, performed in SIM mode and at a sampling rate of 30.7 Hz, described the quantitation of target allergens in fragrances [21]. In this case, the bidimensional chromatograms were greatly simplyfied and, hence, the detection of specific analytes was easier.

The innovative aspect of the present research is the degree of separation/identification, through the three-dimensional GC × GC–qMS application, of both harmless and potentially harmful perfume components. Furthermore, although a wide mass scan range was employed, the quadrupole mass spectrometer provided a high full scan data acquisition rate. The identification of just under 170 components was achieved through mass spectra matching with four different commercial libraries and the interactive use of LRI. Several contact allergens were also identified; peak assignment, in this case, was confirmed by the use of standard components.

Section snippets

Standard components

C8–C36 hydrocarbons in n-hexane solutions (0.1 μg/mL) were purchased from Supelco (Milan, Italy).

Amyl cinnamaldehyde, anisyl alcohol, benzyl alcohol, benzyl cinnamate, methyl 2-octynoate, citral, cinnamaldehyde, benzyl benzoate, benzyl salicylate, cinnamyl alcohol, amylcinnamyl alcohol, coumarin, eugenol, isoeugenol, farnesol, citronellol, geraniol, hydroxycitronellal, hexylcinnamaldehyde, limonene, α-isomethylionone, lilial, linalool, estragole, cis-dihydrocarvone and neo-dihydrocarveol were

Results and discussion

In preliminary GC × GC–qMS applications on the perfume sample, a series of stationary phase combinations were tested. Most comprehensive GC investigations reported in literature are based on the use of a primary apolar and a secondary polar column, as this type of combination provides a true orthogonal separation. It must be emphasized that total orthogonality is not always the most suitable choice and other column sets can be more rewarding [22]. In the present research, though, the classical

Conclusions

The GC–MS determination of a perfume formulation is a cumbersome challenge. This, even when dual analysis on different stationary phases is carried out, as the presence of several major and trace-level components, as well as target allergens must be identified within a very complex sample.

The GC × GC–qMS method, developed in the present research, proved to be a more suitable alternative in this type of application. A great improvement, in the analysis of a completely unknown matrix, was achieved

Acknowledgement

The authors gratefully acknowledge the Shimadzu Corporation for the continuous support.

References (26)

  • A. van Asten

    Trends Anal. Chem.

    (2002)
  • C.G. Fraga

    J. Chromatogr. A

    (2003)
  • P. Marriott et al.

    Trends Anal. Chem.

    (2002)
  • J. Dallüge et al.

    J. Chromatogr. A

    (2003)
  • B.A. Mamyrin

    Int. J. Mass Spectrom.

    (2001)
  • J. Dallüge et al.

    J. Chromatogr. A

    (2002)
  • C. Debonneville et al.

    J. Chromatogr. A

    (2004)
  • C.A. Cramers et al.

    J. Chromatogr. A

    (1999)
  • D.H. Pybus et al.

    The Chemistry of Fragrances

    (1999)
  • S.C. Rastogi et al.

    Contact Dermat.

    (2003)
  • S.C. Rastogi

    J. High Resolut. Chromatogr.

    (1995)
  • K. Ellendt et al.

    SÖFW J.

    (2001)
  • A. Chaintreau et al.

    J. Agric. Food Chem.

    (2003)
  • Cited by (93)

    • Untargeted volatile metabolomics using comprehensive two-dimensional gas chromatography-mass spectrometry – A solution for orange juice authentication

      2020, Talanta
      Citation Excerpt :

      The alkane compounds were completely separated by the first column, while did not resolve well in the second column (Fig. S2). This result is in accordance with the properties of the two columns utilized in this study and with previous publications [27]. Involving different separation mechanism, the two GC columns performed differently in retaining different molecules.

    • Detectors and basic data analysis

      2020, Separation Science and Technology (New York)
    • Simultaneous quantification of fifty-one odor-causing compounds in drinking water using gas chromatography-triple quadrupole tandem mass spectrometry

      2019, Journal of Environmental Sciences (China)
      Citation Excerpt :

      Gas chromatography coupled to mass spectrometry (GC/MS) has long been the main method for the determination of odorants in water samples. However, this method is not suitable for the determination of multiple odorants with a wide spectrum of physical and chemical properties due to its limited separation capacity and sensitivity (Mondello et al., 2005; Tsugawa et al., 2014). Guo et al. (2015) have established a quantification method for simultaneous determination of 54 typical odor-causing compounds in source water based on comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS).

    View all citing articles on Scopus
    View full text