| Food safety is a hot topic currently. The development of rapid determination technology is great significance for food analysis. Sample preparation plays a key role in food analysis. The research and development of rapid, simple and green pretreatment technologies in food analysis is in the edge-of-state in this field. In this paper, a new sample preparation technique, subcritical water extraction, has been studied and applied to the extraction of formaldehyde in dried beancurd sticks and chloramphenicol, oxytetracycline, tetracycline in feed., and compared with other pretreatment methods. The optimized conditions of subcritical water extraction have been studied too. The main results of this thesis are as follows:1. By acetylacetone spectrophotometric method, the extraction of formaldehyde from dried beancurd sticks by subcritical water was studied. The optimal conditions were obtained to be: 0.3g dried beancurd sticks sample, 10mL distilled water including 0.1mL 1:1 phosphoric acid, under 120℃for about 5 min. Compared with the Standard Method of distillation(NY-5172-2002), the subcritical water extraction method achieves higher extraction efficiency and better precision.2. The extraction of chloramphenicol from feed by subcritical water was studied. The optimal conditions were obtained to be: 0.1g feed sample, 5.5mL deionized water under 105℃for about 10 min. Compared with the National Standard Method of People's Republic of China (GB/T 8381.9 2005), the subcritical water extraction can get shorter extraction time, higher extraction efficiency and less pollution to environment.3. The extraction of chloramphenicol, oxytetracycline, tetracycline from feed by subcritical water was studied. The optimal conditions were obtained to be: 0.1g feed sample, 5.5mL deionized water with pH=2 under 100℃for about 5 min. Compared with ultrasonic extraction, the subcritical water extraction is simple and rapid, and can get higher extraction efficiency and better precision.
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