title: Experimental validation of an effective carbon number-based approach for the gas chromatography-mass spectrometry quantification of 'compounds lacking authentic standards or surrogates'.
abstract: For the quantitative analysis of 'compounds lacking authentic standards or surrogates' (CLASS) in environmental media, we previously introduced an effective carbon number (ECN) approach to develop an empirical equation for the prediction of their response factor (RF). In this research, a series of laboratory experiments were carried out to benchmark the reliability of an ECN approach for sorbent tube/thermal desorption/gas chromatography (GC)/mass spectrometry (MS) applications. First, the ECN values were determined using external calibration data from 25 reference volatile organic compounds (VOCs) using two MS dectectors (quadrupole (Q) and time-of-flight (TOF)). Then, a certified standard mixture of 54 VOCs was analyzed by each system as a simulated unknown sample. The analytical bias, assessed in terms of percentage difference (PD) between the certified and ECN-predicted mass values, averaged 19.2±16.1% (TOF-MS) and 28.2±27.6% (Q-MS). The bias using a more simplified carbon number (CN)-based prediction increased considerably, yielding 53.4±53.3% (TOF-MS) and 61.7±81.3% (Q-MS). However, the bias obtained using the ECN-based prediction decreased significantly to yield average PD values of 9.84±7.28% (TOF-MS) and 16.8±8.35% (Q-MS), if the comparison was limited to 26 (out of 54) VOCs with CN≥4 (i.e., 25 aromatics and hexachlorobutadiene).
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 133-791, Republic of Korea.
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 133-791, Republic of Korea. Electronic address: kkim61@hanyang.ac.kr.
authors.forename: Ki-Hyun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 133-791, Republic of Korea.
authors.forename: Jan E
authors.initials: JE
authors.lastname: Szulejko
authors.affiliation: Department of Environmental Engineering, Mokpo National University, Mokpo, Republic of Korea.
authors.forename: Min-Suk
authors.initials: MS
authors.lastname: Bae
authors.affiliation: Analytical Science Division, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK.
authors.forename: Richard J C
authors.initials: RJ
authors.lastname: Brown
keywords: Carbon number; Effective carbon number; Gas chromatography/mass spectrometry applications; Sorbent tube; Thermal desorption; Volatile organic compound