Analytical Sciences

Application of a Novel Large-Volume Injection Method Using a Stomach-Shaped Inlet Liner in Capillary Gas Chromatographic Trace Analysis of Dioxins in Human Milk and Plasma

Koichi SAITO,*¹ Atsuko OHMURA,*² Mikiko TAKEKUMA,*² Ryoichi SASANO,*³ Yasuhiko MATSUKI,*⁴ and Hiroyuki NAKAZAWA*¹

*1 Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo 142-8501, Japan
*2 Biological Effect Research Group, Saitama Institute of Public Health, 639-1 Kamiokubo, Sakura, Saitama 338-0824, Japan
*3 AiSTI SCIENCE Co., Ltd., 75-2 Kuroda, Wakayama 640-8341, Japan
*4 Institute of Food Hygiene, Japan Food Hygiene Association, 2-5-47 Tadao, Machida, Tokyo 194-0035, Japan

A newly developed large-volume injection (LVI) technique that employs a unique stomach-shaped inlet liner (SSIL) inside of a programmable temperature vaporizer was used for the determination of trace amounts of dioxins in human milk and plasma. The initial temperature and the initial dwelling time of the inlet and the kind of solvent used were found to be critical in determining the analytical sensitivity of dioxins due to the loss of these relatively volatile compounds during solvent vaporization. Human milk and plasma were purified and fractionated by pre-packed multi-layered silica-gel chromatography and activated carbon silica-gel column chromatography. A 20-µL aliquot of the fraction collected from the chromatography with toluene was directly applied to the LVI system in high-resolution gas chromatography/high-resolution mass spectrometry. Excellent correlation (r > 0.97) between the values obtained by the LVI method using the SSIL device and those by the conventional regular-volume splitless injection method was obtained for PCDDs, PCDFs and non-ortho PCBs in human milk and plasma samples.

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