Studies on Analysis Method of Organic Mercury and Organic Tin, and Levels of Heavy Metals in Fish and Shellfish

• Main Authors: Syr-Song Chen, 陳石松
• Other Authors: Deng-Fwu Hwang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/47241683096875061526

博士 === 國立臺灣海洋大學 === 食品科學系 === 92 === The pollution problem of seafood with heavy metals is still a concerning issue judging from both hygienic and ecotoxicological points of view. The purpose of this study is to develop the analysis method of organic mercury and tin, and then establish the database of the organic mercury and heavy metals in fish, and organic tin and heavy metals in shellfish. The analytical procedure for analysis of mercury species in fish was developed. It involved microwave-assisted digestion with alkaline solution (tetramethylammonium hydroxide), neutralization using acetic acid, addition of Cu++ and acetate buffer (pH 5) aqueous-phase derivatization with sodium tetraethylborate or acetate buffer (pH 4) aqueous-phase derivatization of mercury species with sodium tetrapropylborate, and subsequent extraction with n-heptane. The various mercury derivatives were desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by electron impact mass spectrometry. Optimum conditions allowed sample through out to be controlled by the instrumental analysis time (near 10 min per sample) but not by the sample preparation step. At the power of 15–30, 45, 60–75 W, sample preparation time is only 3.5, 2.5, and 1.5 min, respectively. The proposed method was finally validated by the analysis of three biological certified reference materials, BCR CRM 464 tuna fish, NRC DORM-2 dogfish muscle, and NRC DOLT-2 dogfish liver. The detection limit of the overall procedure was found to be 0.040 mg/g of biological tissue for mercury species. The recoveries of mercury species were 92.3–96.4% and 93.6–95.5% for methyl- and inorganic mercury of ethylation, and 91.2–94.7%, 93.8–97.8%, and 94.3–97.4% for methyl-, ethyl-, and inorganic mercury of propylation, respectively. The detected and certified values of methylmercury of three biological certified reference materials were as follows: 5.31 ± 0.32 mg/g (mean ± S.D.) mg/g and 5.50 ± 0.17 mg/g for BCR CRM 464 tuna fish, 4.40 ± 0.34 mg/g and 4.47 ± 0.32 mg/g for NRCC DORM-2 dogfish muscle, and 0.663 ± 0.061 mg/g , and 0.693 ± 0.053 mg/g for NRCC DOLT-2 dogfish liver for ethylation, and 5.34 ± 0.30 for BCR CRM 464 tuna fish, 4.34 ± 0.24 mg/g for NRCC DORM-2 dogfish muscle and 0.652 ± 0.055 mg/g for NRCC DOLT-2 dogfish liver for propylation, respectively. It indicated that the method was well available to detect the mercury species in fish. The analytical procedure for butyltin in oyster was developed. It involved microwave-assisted digestion with alkaline solution (tetra methylammonium hydroxide), neutralization using acetic acid, aqueous-phase derivatization with sodium tetrapropylborate, and subsequent extraction with isooctane. The various butyltin derivatives were desorbed in the splitless injection port of a gas chromatograph and subsequently analyzed by chemical ionization mass spectrometry. Optimum conditions allowed sample throughput to be controlled by the instrumental analysis time (near 19 min per sample) but not by the sample preparation step. At the irradiation power of 45 W, sample heating time is only 3.0 min. The proposed method was finally validated by the analysis of biological certified reference materials (BCR CRM 477 mussel tissue). The detection limit of the overall procedure was found to be 0.020 mg/g of biological tissue for butyltin species. The recoveries of butyltin species of clam and oyster were 69.3–77.3% and 67.1–74.4%, 89.3–92.7% and 87.2–93.6%, 92.1–97.2% and 94.7–98.6%, and 92.5–95.2% and 95.4–98.2% for MBT, DBT, TBT, and TeBT, respectively. The detected and certified values of butyltin of BCR CRM 477 mussel tissue were as follows: 1.33 ± 0.38 (mean ± S.D.) mg/g and 1.50 ± 0.28 mg/g for MBT, 1.62 ± 0.23 mg/g and 1.54 ± 0.12 mg/g for DBT, 2.35 ± 0.16 mg/g and 2.20 ± 0.19 mg/g for TBT, respectively. It indicated that the method was well available to detect the butyltin species in oyster. Adopted AAS, AFS and GC-MS method to analyze 591 fish samples. The results showed that total average content of Hg, MeHg, Zn, Cd, Pb, Cu, Ni, and Sn were 0.881 mg/g (0.01–13.8 mg/g), 0.639 mg/g (＜0.04–10.9 mg/g), 7.56 mg/g (1.98–34.3 mg/g), 0.022 mg/g (0.002–0.176 mg/g), 0.022 mg/g (0.002–0.249 mg/g), 0.957 mg/g (0.11–8.13 mg/g), 0.037 mg/g (<0.02–0.380 mg/g) and 0.012 mg/g (<0.02–0.095 mg/g). Adopted AAS and GC-MS method to analyze 190 shellfish samples which were purchased from markets. The results showed that total average content of Pb, Cd, Ni, Cr, Cu, Zn, MBT, DBT, TBT and TeBT were 0.116 mg/g (<0.004–0.343 mg/g), 0.114 mg/g (<0.001–0.538 mg/g, 0.228 mg/g (<0.002–1.091 mg/g), 0.155 mg/g (0.007–0.625 mg/g), 37.5 mg/g (0.10–348.2 mg/g), 87.7 mg/g (4.6–580.9 mg/g), 4.6 ng/g (<20–234.3 ng/g), 37.0 ng/g (<20–206.0 ng/g), 43.5 ng/g (<20–376.0 ng/g) and 12.7 ng/g (<20–89.4 ng/g).