GC-MS Determination of 8 Volatile Benzene Homologues in Ink of Marking Pen with Purification by Solid Phase Extraction

0.200 0 g of ink in the core of a marking pen was taken and extracted with 5.0 mL of ethylacetate for 2 min. The extract was purified by passing through HLB solid phase extraction column. Eluate together with the washings was collected, and its volume was made up to 10.0 mL with ethylacetate. After filtering through 0.22 μm filtering membrane, the filtrate was used as testing solution for determination of 8 volatile benzene homologues (i.e., benzene, toluene, ethylbenzene, p-xylene, m-xylene, iso-propyl-benzene, o-xylene and styrene) by GC-MS under the working condition of the instrument. HP-INNOWax capillary chromatographic column with programmed temperature elevation in the range from 35℃ to 220℃ was adopted for the separation of the 8 benzene homologues, and then determined by MS under the mode of EI and SIM. Linearity ranges of the standard curves of the 8 benzene homologues were found same in the range of 0.1-5.0 mg·L^-1. Detection limits (3S/N) found were in the range of 0.06-0.18 mg·kg^-1. On the base of blank samples, mixed standard solutions at 3 concentration levels were added and recovery test were performed. Recoveries of the 8 compounds were found in the range of 79.8%-114%. Values of RSDs (n=5) found were ranged from 0.20% to 11%. 116 marking pens with ink of various colors were analyzed by the present method, rate of detection of the 8 benzene homologs attained to a value of 76.9%, with their mass fractions in the range of 0.33-3.49×10⁴mg·kg^-1.