The Total Volatile Organic Compounds Concept

Hundreds of VOCs are present in some typical indoor environments. It is therefore not practically possible to identify and quantify every compound, even with the most sensitive and selective techniques [5]. Consequently, different techniques have been used to express the TVOCs (for reviews of the methods see Refs. [2,5,12,32]). 

To redress problems caused by the different approaches to TVOC estimation, a uniform procedure was proposed [2,12]. The procedure, which is based on sampling of VOCs on Tenax tubes followed by thermal desorption and GC/MS analysis (with nonpolar columns), proposed that TVOC be defined as 

The procedure further recommends that as many VOCs as possible should be quantified in the analytical window bounded by the retention times of hexane and hexadecane, and that these VOCs should as far as possible include the 64 VOCs that are of special interest to the European Community [2]. A major shortcoming of the recommendation is that not all VOCs present in indoor air are included in the approach. For example, important indoor VOCs like 2-propanol, 2-methylpentane, 3-methylpentane and butanal elute before hexane while texanolisobutyrate elutes after hexadecane [60]. It was also expected that the definition would enhance interlaboratory TVOC values, classification and screening of indoor materials, and the identification of problems with ventilation design, indoor activities or materials [12]. However, De Bortoli et al. [73] observed large variances in interlaboratory studies performed with the approach. Nevertheless, it has been adopted in many recent indoor air studies [10,60,74]. 

---