碩士 / 國立中興大學 / 獸醫學系 / 93 / The aims of this study are to develop an accurate method for determination of tissue residual levels of cobia fed with amoxicillin (AMX). AMX was extracted from various cobia tissues in phosphate buffer solution by solid-phase extraction. Then samples were subjected to derivatization by trichloroacetic acid (TCA) and formaldehyde in boiling water for 30 mins. HPLC separation of AMX was carried out on a XTerra® C18 column with mobile phase of 25 mM K2HPO4 (pH 8.5) and acetonitrile at a ratio of 80 : 20 (v/v). The excitation and emission wavelength are 358 nm and 440 nm, respectively. Under these conditions, the retention time of AMX was 3.9 min. The coefficient of variations of the AMX concentration were between 0.4 – 4.6 % for both intra and inter day precision. The R-squares of standard curves (1 - 0.01 ppm) were 0.9998 and 0.9999, respectively. The recoveries of blank cobia tissues spiked with AMX (1 - 0.01 ppm) were 82.0 - 100.9 % in muscle, 92.4 -102.0 % in liver, 81.2 - 89.6 % in kidney, 90.7 - 94.4 % in skin, and 85.1 - 94.6 % in plasma. The limits of detection (LOD) for tissues were 0.3 ppb except for liver, which was 0.5 ppb. The limits of quantitation (LOQ) were 0.45 ppb in muscle, 1.2 ppb in liver, 0.8 ppb in kidney, 0.5 ppb in skin, and 0.5 ppb in plasma. For residual experiment, 120 cobias weighted 76.62 ± 12.55 g were divided into one control and 2 dosage groups (40 and 60 mg/kg BW). AMX was given once daily per oral for 5 days before plasma, muscle, liver, skin and kidney were sampled for measurement of AMX concentration at 2, 4, 8, 24, 48, 72, 96 and 120 hrs post the final AMX administration. The maximum concentration in plasma (60 mg/kg BW group: 4.97 ± 1.94 ppm; 40 mg/kg BW group: 3.34 ± 0.87 ppm) was 2-2.5 folds higher than that in the tissues at 2 hrs post the final drug administraion. The drug concentration decreases precipitately in various tissues. Forty-eight hrs after administration, all tissues had AMX concentration below the maximal residual limit of 0.01 ppm. In order to determine whether the excreted parent AMX in the water would affect the tissue residual level, tilapias administrated with AMX (60 mg/kg BW) for 5 days by gastric catheterization were studied. Plasma, muscle, liver, skin and kidney levels of AMX were measured at 1 and 2 hrs after the final administration of AMX. At 1, 2, 4 and 8 hrs after the final drug administration, pool water was also sampled to determine the AMX concentration. The results showed that the AMX concentration were 1.80 ± 0.68 ppm in muscle, 1.89 ± 0.46 ppm in liver, 2.89 ± 0.53 ppm in kidney, 0.02 ± 0.01 ppm in skin, and 5.15 ± 0.86 ppm in plasma, at 1 hrs post the AMX fiinal administration. All the water samples contained AMX concentration that was under the LOQ (0.5 ppb), suggesting that the excreted AMX should not affect the tissue residual level of tilapias and cobias. In conclusion, we have developed a sensitive HPLC method that could efficiently detect trace levels of AMX in cobia and tilapia. After 5 consecutive oral doses of AMX, cobia tissue levels of AMX were under maximum residue limit of 0.01 ppm within 48 hrs after last oral treatment. At the dosage (40 mg/kg BW), we suggestes that the recommended withdraw period was 5 days.
| Identifer | oai:union.ndltd.org:TW/093NCHU0541004 |
| Date | January 2005 |
| Creators | Po-Hsin Su, 蘇柏欣 |
| Contributors | Shu-Peng Ho, 何素鵬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 124 |
Page generated in 0.0094 seconds