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This national assessment program was established by the China National Accreditation Service for Conformity Assessment (CNAS) to evaluate the aflatoxin-testing proficiency of a cross-section of Chinese laboratories. The Shan Dong Inspection and Quarantine Bureau of China conducted the assessment according to ISO 13528:2005 (E) and the International Harmonized Protocol for Proficiency Testing. The 77 laboratories that participated in the study had either been previously accredited by CNAS or were candidates for CNAS accreditation. The analytic samples for this testing scheme were prepared from naturally contaminated peanuts and diluted to approximately 10 g/kg for aflatoxin B1 and 18 g/kg for total aflatoxins. The Ss/p test (with a required result of Ss 0.3p) was used to evaluate the homogeneity of the test samples; sample stability was confirmed with a t-test. The performance of each laboratory was designated by a z-score that was calculated using robust statistics. The robust mean of the participants' results in this study was nearly coincident with the median. A modified Horwitz equation was used to determine the standard deviation. The study compared analytic results obtained by 5 different methods: high-performance liquid chromatography (LC), enzyme-linked immunosorbent assay, thin-layer chromatography, fluorometry, and LC with tandem mass spectrometry. A satisfactory performance rating required z-scores between 2 and 2 for the target analytes. Of the 73 laboratories that reported results for aflatoxin B1, 66 (90.4) performed satisfactorily. Of 32 laboratories that reported total aflatoxins (B1 B2 G1 G2), 30 (93.8) performed satisfactorily. Laboratories whose performance ratings were questionable or unsatisfactory were re-evaluated in a second interlaboratory comparison.

The tocopherols inRhodiola sachalinensiswere determined with adsorption column chromatographic purification and GC/MS. Tocopherols were extracted by sonication and Soxhlet with ethanol and dichloromethane, respectively. The extract was partitioned with chloroform and water using liquid-liquid extraction, and water part was partitioned with ethyl acetate, and purified with a silica column. Three type of tocopherols such as α, β, γ-tocopherol were identificated fromRhodiola sachalinensisby GC/MS. All of the three types of tocopherols were determined in the chloroform part, with some sterol and sterol conjugates. The similarities of the three types of tocopherols were nearly or above 90%, and the retention time of α, β, γ-tocopherols were 24.085, 23.194, and 22.458min, respectively.

Recently, molecularly imprinted solid phase extraction (MISPE) has been used more frequently separate drugs and natural substances. This modern separation methodologies require reliable tools that perform on a high level in terms of efficiency and reproducibility. The molecular imprinting technique is a reliable technique for the preparation of materials of predetermined selectivity. It is highly significant in research of the structure of enzyme, mechanism of receptor-antibody and analytical chemistry. Solid phase extraction can be used to isolate and pre-concentrate the analytes in complex samples. This technique is more rapid, simple, economical and environment-friendly than the traditional liquid-liquid extraction. The materials used in SPE are usually based on the non-specific binding of the targets, which often suffers some shortcomings, such as low specificity and selectivity. In recent years, solid phase extraction involving molecular imprinted polymer have been proved to be successful applications for its features of high selectivity, ease of synthesis, low cost for preparation and workability under different conditions especially that of harsh pH and organic solvents. In this work, the principles, application and development tends of MISPE will be reviewed and the disadvantages and limitation of the MISPE and future development direction are also briefly discussed.