Department of Chemistry, National Taiwan Normal University, 88 Sec. 4, Tingchow Road, Taipei, Taiwan.
J Chromatogr A. 2012 Jan 13;1220:143-6. doi: 10.1016/j.chroma.2011.12.006. Epub 2011 Dec 9.
The Hadamard transform-gas chromatography/mass spectrometry (HT-GC/MS) technique was successfully employed for the detection of hexamethyldisiloxane (HMDSO, C(6)H(18)OSi(2)) at the sub-nL/L level in a semiconductor wafer cleanroom. Indoor air samples were collected from the room, according to EPA Method TO-17 using a Tedlar bag where the air samples were allowed to pass through an absorption tube for 24 h. The condensed components were then heated and simultaneously injected into a GC column through a Hadamard-injector, which was operated in accordance with the Hadamard codes. Compared to the single injection used in most GC/MS systems, the signal-to-noise (S/N) ratios were substantially improved after the inverse Hadamard transformation of the encoded chromatogram. Under optimized conditions, when cyclic S-matrix orders of 255, 1023 and 2047 were used, the S/N ratios of the HMDSO signals were substantially improved by 7.4-, 15.1- and 20.1-fold, respectively. These improvements are in good agreement with theoretically calculated values (8.0-, 16.0- and 22.6-fold, respectively). We found that when the HT-GC/MS technique was applied, HMDSO could be detected at the 0.1 nL/L level.
Hadamard 变换-气相色谱/质谱（HT-GC/MS）技术成功地用于检测半导体晶片洁净室中纳升/升以下水平的六甲基二硅氧烷（HMDSO，C(6)H(18)OSi(2))。根据 EPA 方法 TO-17，使用 Tedlar 袋从房间中收集室内空气样品，其中空气样品通过吸收管 24 小时。然后将冷凝成分加热并通过 Hadamard 进样器同时注入 GC 柱，该进样器根据 Hadamard 码操作。与大多数 GC/MS 系统中使用的单次进样相比，在对编码色谱进行逆 Hadamard 变换后，信号与噪声（S/N）比得到了显著提高。在优化条件下，当循环 S-矩阵阶数为 255、1023 和 2047 时，HMDSO 信号的 S/N 比分别提高了 7.4 倍、15.1 倍和 20.1 倍。这些改进与理论计算值（分别为 8.0 倍、16.0 倍和 22.6 倍）非常吻合。我们发现，当应用 HT-GC/MS 技术时，HMDSO 可以在 0.1 nL/L 水平下检测到。
