S. Kim / Journal of Hazardous Materials 176 (2010) 14–19
Table 3 Analysis conditions of HPLC for formaldehyde.
Variables Formaldehyde analysis condition HPLC Agilent HP1100 Detector UV–vis 365(Bw.30), ref. 590(Bw.10) Column Supelco C18. 4.6mm×250mm Mobile phases Acetonitrile:water=45:55 Analysis time 25min Injection volume 20L Column temperature 40◦C Mobile phase flow rate 1.0mL/min
Table 4 Analysis conditions of GC/MS for VOCs.
Variables VOCs analysis condition TDS PerkinElmer ATD400 GC/MS HP6890/Agilent5973 Column RTX-1 (105m×0.32mm×3m) Carrier gas and flow He (99.99%) Temperature program 40◦C (5min)→70◦C (5min)→150◦C (5min)→200◦C (5min)→220◦C (5min)→240◦C (5min)
MS condition Mode EI (electron ion) Electron energy 70eV Detection mode TIC (scan), m/z: 35/350
for 30min under a gas flow rate of 150mL/min while 1.5L of gas wascollectedinaTenax-TAtubefor30minunderagasflowrateof 50mL/min.TheconditionoftheFLECforthecorrectiongasislisted in Table 2. The replicates of each sample were three times. Formaldehyde and VOCs were analyzed by HPLC and TDS/GC–MS, respectively, as listed in Tables 3 and 4. In this paper, TVOC was defined as the conversion of all peak areas between C6 and C16 to concentrations using the toluene response factor. A peak area under 10 was defined as the limit of detection. ThesamplegaswastakenwithTenax-TAand2,4-DNPHcartridges. The calculation of the emission factor (EF) is explained in ASTM D5116. Two technical terms of EF and ER are commonly used to describe the rate of emissions from indoor materials, and are related as follows: ER=A(EF)
where ER is the emission rate (mg/h); A is the source area (m2); EF is the emission factor (mg/m2 h).
2.2.2. VOC analyzer The VOC analyzer is a portable device to measure the four main aromatic hydrocarbon gases: toluene, ethylbenzene, xylene and styrene. To prepare the samples for the VOC analyzer, the each flooring samples were conditioned at 20◦C and 50±5% in a thermo-hygrostat for 15 days, then cut into four pieces measuring 50mm×50mm and placed in a 3L polyester plastic bag. The polyester plastic bag was sealed with teflon tape, purged three times with N2 gas, and then filled with N2 gas by pulling up the plunger. For the blank control, an empty bag with N2 gas was prepared. The gases for the VOC analyzer were collected from the 3L polyester plastic bag in a gas tight (0.5cc) manner after 4 days, placedintotheVOCanalyzerandanalyzed.Thisprocessisshownin Fig. 2. This 4-day period was determined by the authors’ previous study to find the optimum method for VOC emission test by the VOC analyzer [25]. The measurement procedure comprised three steps. First, the product was inserted into the 3L polyester plastic bag. Then, the plunger was slowly pulled, pushed in again, and pulledoutforthesecondtimebeforethesyringewasremovedfrom the plastic bag. If the top of the syringe was wet, it was wiped dry with a tissue. A dedicated needle was attached and 0.5cc (1/2 calibration) of the sampled gas was ejected by pushing the plunger. The remaining gas was injected into the inlet on the main unit of theVOCanalyzer,afterwhichthemeasurementwasautomatically started [26].