| Endocrine Disrupting Chemicals (EDCs) are a heterogeneous group of substances, which have been received widely attention because their function of interfering with the endocrine,immune,reproductive and neurological system of wildlife and human by simulating the physiological or biochemical function of organism. Steroids endocrine disrupting chemicals are a group of biologically active compounds which are synthesized from cholesterol and belong to the EDCs. Steroids endocrine disrupting chemicals have a stronger endocrine disruption effect and are more harmful to organisms even at very low concentration compared with other EDCs and synthetic chemicals.In practical work, environmental trace analysts are in favor of Gas Chromatography-Mass spectrometry (GC-MS) because of its higher resolution, relatively fast analysis speed, avoidance of excessive solvent waste and lower operation cost. But the direct GC-MS analysis without derivatization will easily lead to the absorption in the column and decrease the sensitivity of GC-MS, because steroids endocrine disrupting chemicals'thermal instability, weak volatility and polar functional groups such as hydroxyl and ketone groups. Therefore, steroids endocrine disrupting chemicals should be transformed into corresponding derivatives which are less polar, more volatile and have higher thermal stability to suit for the trace GC-MS analysis by improving the chromatographic sensitivity and component separation.In this paper, based on systematic study of the technical principles, applications and problems of the current hydroxyl and ketone groups'derivatization technology, the hydroxyl and ketone groups'derivatization were summarized. In this study, the hydroxyl and ketone groups'derivatization of the five highly potent steroid endocrine disrupting chemicals (estrone (El),17-(3-estradiol (E2),17-a-ethynylestradiol (EE2), Estrogen estriol (E3) and progesterone (PROG)) in environment were systematic studied. By using different derivatization technology, as well as controlling and optimizing derivatization conditions, including the amount of the catalyst, derivatization reagents, temperature, time and the solvent, the hydroxyl and keto groups of the five steroids endocrine disrupting chemicals can be well derivatized. Under optimized derivatization conditions, the derivatization effects along with the sensitivity of GC-MS were discussed, and the calibration curves were also drawed.As the conclusion, the optimized derivatization conditions were 100μl N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)/trimethyliodosilane (TMIS)/ Dithioerythreitol (DTE) (1000:2:5, v/v/w) at room temperature (around 20℃) for 5 min. Under the optimized conditions, hydroxyl and ketone groups in the five steroids were successfully derivatized and the derivatives such as di-TMS-E1,di-TMS-E2,di-TMS-EE2,tri-TMS-E3 and di-TMS-PROG were well observed. The results also showed? that, temperature and reaction time have only limited effect on the derivatization. Derivatization react at room temperature (20℃) for 5 min has achieved the best results. The derivatives of target compounds were stable because their RRFs were no observable change when deposited 48h at -20℃. The byproduct of EE2 was never obsvered. The limits of detection (LOD) of E2 was 0.01 pg/μL, E1,EE2,E3 were 0.1pg/μL, PROG was 1pg/μL. A good linearity of response with a coefficient r2> 0.994 for quantitative analysis was obtained.The Linear range of E2 was 0.1～500pg/μL, E1,EE2,E3 was 1-500pg/μL and PROG was 5-500pg/uL. Therefore, it was demonstrated that the simultaneous hydroxyl and ketone groups'derivatization technology was an efficient and suitable derivatization method for the analysis of steroids endocrine disrupting chemicals by GC-MS. |
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