No abstract

A new approach for the determination of 2-acetyl-4(5)-(tetrahydroxybutyl)imidazole (THI) in ammonia caramel color has been developed. THI was extracted from samples by cation-exchange solid-phase extraction (SPE). After the cation exchange column extraction, a phenyl boronate agarose (PBA-30) affinity column was used for further cleanup. In the boronate extractor, a cyclic boronate ester was formed between the tetrahedral boronate anion and the ds-diol groups of THI. THI was isolated from most remaining matrix interferences and was recovered by cleaving the formed ester with acetic acid. The collected samples were then determined by HPLC-UV, using a diol bonded phase column. The optimum HPLC conditions for the separation of THI from ammonia caramel color matrices were also investigated. The minimum detection limit of THI by this approach was at the 1 ppm level in ammonia caramel color.2-Acetyl-4( 5)-(tetrahydroxybutyl)imidazole (THI) (Figure 1) is a compound that may be formed during the production of ammonia caramel color. Previous methods for determining THI have employed cation-exchange solidphase extraction followed by reversed-phase HPLC with UV detection (Kroplien, 1986;Kroplien et al., 1985; Lawrence, 1987). These methods suffered from incomplete chromatographic resolution of THI from caramel matrix compounds. Thus, there exists a need to develop improved methods for the determination of THI.We have now developed a new and improved approach

Web Service involves many participants including service developers, providers, UDDI, and clients, and provides a kind of distributed architecture model. Different participants of the web service own different resource related to the service, so, the test method they use will be also different. From the perspective of service users, the paper proposes a service test model. The model is mainly consist of three sub-models including the user requirements model, the WSDL model, and the generation model of the test cases. Users can make a function test by using the model only with the WSDL document. According to the test model, a prototype tool is implemented. In the last, an example is given to simulate the process of service test and validate the feasibility of the model.