[Determination of 15 halogenated polycyclic aromatic hydrocarbons in aquatic products by stable isotope dilution coupled with gas chromatography-triple quadrupole mass spectrometry].

Halogenated polycyclic aromatic hydrocarbons (H-PAHs), including chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and brominated polycyclic aromatic hydrocarbons (Br-PAHs), are compounds in which one or more hydrogen atoms replaced by chlorine or bromine atoms. These compounds are not only difficult to degrade but also highly fat soluble and toxic. They are a new type of high-risk organic pollutants with structures similar to those of dioxins, and their toxicity is even higher than that of the parent polycyclic aromatic hydrocarbons (PAHs). The bioaccumulation of H-PAHs can be predicted by their octanol-water partition coefficient (Kow); in general, higher bioaccumulation capacity and Kow values indicate greater fat solubility. Therefore, animal-derived foods with higher fat contents, such as animal meat, milk, aquatic products, and their processed forms, are more likely to be contaminated with higher contents of H-PAHs than those with lower fat contents. In this work, a gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) method coupled with stable isotope dilution was established to determine 15 H-PAHs in aquatic products. The instrument and pretreatment methods were systematically optimized. The GC-MS/MS used in this method can effectively eliminate matrix interferences and features high sensitivity and low analytical cost; thus, it has good application prospects. The samples were added with an isotope internal standard before extraction to calibrate the loss of the tested substance during the pretreatment process, extracted by accelerated solvent extraction, purified using gel permeation chromatography and PRiME HLB columns, and then analyzed by GC-MS/MS. The use of two DB-5MS chromatographic columns (30 m×0.25 mm×0.25 µm) and microplate fluidics technology to connect chromatographic columns 1 and 2 in series led to better separation effects, good peak shapes, and high target compound responses. The 15 H-PAHs demonstrated good linearities in the range of 1-50 µg/L, with correlation coefficients (r) greater than or equal to 0.993. The relative standard deviation (RSD) values of the relative response factor (RRF) of the H-PAHs were less than 9%, the method detection limit (MDL) was 0.009-0.072 µg/kg, and the method quantification limit (MQL) was 0.031-0.240 µg/kg. Three spiked levels of 0.25, 1.0, 2.5 µg/kg were added to the blank samples to determine the recovery and precision. The recoveries for these spiked levels were 74.6%-116.8%, 77.8%-123.2%, and 71.9%-124.8%, respectively, and the corresponding RSDs were 0.6%-8.2%, 0.6%-9.0%, and 0.4%-10.6%, respectively. The total actual content of H-PAHs in aquatic product samples was 0.60-3.54 µg/kg. Among the H-PAHs investigated, 9-chlorophenanthrene (9-ClPhe) showed the greatest detection rate (100%) and highest content (1.15 µg/kg), indicating that H-PAHs widely exist in aquatic products. Thus, further assessment of the dietary exposure risk of these compounds is necessary. The developed method simplifies the pretreatment step, and has the advantages of simplicity, rapid analysis, high recoveries, and good stability. It is suitable for the qualitative and quantitative analysis of H-PAHs in actual aquatic product samples and provides reliable technical support for the residue status and risk assessment of H-PAHs in aquatic products.

Two new coumarin glycosides from Peucedanum praeruptorum.

Two new coumarin glycosides, praerosides VI (1) and VII (2), were isolated from the roots of Peucedanum praeruptorum Dunn. Their structures were elucidated by chemical reaction and NMR spectroscopic methods.

[Isolation and purification of total tubeimosides from Bolbostemma paniculatum by macroporous resin].

OBJECTIVE: To select the optimum purification process of all tubeimosides from Bolbostemma paniculatum by macroporous resin. METHOD: Static absorption test and deabsorption test were carried out to screen the best macroporous resin for all tubeimosides. The single factor test, orthogonal experimental designs and variance analysis were applied to optimize the manipulation parameters of macroporous resin. RESULT: The macroporous resin NKA possessed the strongest absorption ability to all tubeimosides among the 9 resins studied, in addition to an easy de-absorption property. The optimum absorption conditions were A2B3C1, namely concentration of feed 30 mg x mL(-1), diameter: height of the chromatography column 1:7, the weight ratio of raw material and resins 1:2. CONCLUSION: The above experimental results can provide experimental basis for large-scale purification process of all tubeimosides.