Mass spectrometry/gas chromatography–mass spectrometry approach for rapid screening/quantitative determination of perchloroethylene in air Pablo Richter a,∗ , Carolina Z ´ u˜ niga a,b , Katia Calder ´ on b , Rodrigo Carrasco b a Facultad de Ciencias Qu´ ımicas y Farmac´ euticas, Universidad de Chile, P.O. Box 233, Santiago, Chile b Centro Nacional del Medio Ambiente (CENMA), Universidad de Chile, Av. Larra´ ın 9975, La Reina, Santiago, Chile Abstract A new mass spectrometry/gas chromatography–mass spectrometry (MS/GC–MS) approach has been developed for the screening and quantitative determination of perchloroethylene (PERC) in workplace and outdoor air samples, which could be extended to the screening and analysis of other analytes and samples. This approach may be rapidly modified in order to be used directly as an MS detector for screening purposes or alternatively as a common GC–MS, for confirmation. The screening alternative by MS is approximately 20 times faster than the quantitative-confirmatory determination by GC–MS. Detection limits of both alternatives are sufficiently low to screen and determine PERC in the above-mentioned matrixes. The advantage of this approach over others previously described is that, in the present case, the sample passes through the chromatographic column only when the confirmatory GC–MS is used. For the MS screening method, the chromatographic column is bypassed by using an appropriate selection valve. In this way, the column lifetime is extended and screening time is considerably shortened. Keywords: Screening system; Mass spectrometry; GC–MS; Perchloroethylene; Air samples 1. Introduction Perchloroethylene (PERC), also known as tetrachloroethy- lene, is a solvent commonly used in dry-cleaning operations. PERC enters the body when breathed in with contaminated air or when consumed with contaminated food or water. Once in the body, PERC can remain stored in fat tissue. This volatile com- pound is regulated as a hazardous air pollutant due to its toxicity. The OSHA method for determination of PERC in the workplace involves the use of adsorbent tubes for sample collection and GC-FID for sample analysis [1]. In the case of outdoor atmo- spheric samples, PERC as well as other VOCs are determined by the TO-14 United States Environmental Protection Agency (US-EPA) method [2], which involves sampling in canisters and GC–MS analysis. The development of rapid screening methods is currently becoming significantly important in analytical chemistry. Con- ventional methods used in analytical laboratories are usually ∗ Corresponding author. Fax: +56 2 678 2809. E-mail address: prichter@ciq.uchile.cl (P. Richter). not compatible with the highly desirable routine and extensive monitoring. When timely decisions are made, the delivery of rapid analytical information, not necessarily possessing a high level of accuracy and precision, is highly appreciated. It must be stressed that screening approaches are not a substitute for but rather a complement to the reference conventional techniques [3,4]. In recent years, there has been an increasing demand for anal- ysis of samples considering their volatile constituents. Mass spectrometry coupled to gas chromatography (GC–MS) has been the most widely used technique to study this type of pollu- tion [5–8] but, as stated above, the development of nonseparative methods for the resolution and determination of different ana- lytes is of great interest owing to their speed. Consequently, the direct coupling of mass spectrometry with methods such as solid-phase microextraction (SPME-MS) [9], or headspace (HS- MS) [10–15], has been developed for the analysis of raw materi- als and foods in the agrofood industry. These techniques provide “fingerprints” of the products under analysis, and the informa- tion, suitably processed by applying chemometric data treatment (such as hierarchical cluster analysis (HCA), linear discriminant analysis (LDA) and soft independent modeling class analogy (SIMCA)), can be used to differentiate such products.