[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.

[Clinical significance of intrahepatic hepatitis B core antigen (+) in patients with chronic hepatitis B].

OBJECTIVE: This study aimed to assess the clinical significance of intrahepatic hepatitis B core antigen (HBcAg) (+) in patients with chronic hepatitis B (CHB). METHODS: 200 CHB patients were prospectively studied using fluorescence quantitative PCR (FQ-PCR), combined PCR with fluorescence probe hybridization technique, to determine serum HBV DNA. Serum HBeAg was measured quantitatively. Liver biopsies were performed and immunohistochemistry stained liver slides were examined in all the cases. Correlation analyses were performed. RESULTS: Based on the HBV DNA levels, the patients were divided into 5 groups: group A (<3 log10 copies/ml) n=20, group B (>or=3 log10 copies/ml-<5 log10 copies/ml) n=13, group C (>or=5 log10 copies/ml-<6 log10 copies/ml) n=24, group D (>or=6 log10 copies/ml-<8 log10 copies/ml) n=116, and group E (>or=8 log10 copies/ml) n=27, and 87.5% of the CHB patients were intrahepatic HBcAg (+). The rate of HBcAg (+) was 55.0% (11/20) in group A, 53.8% (7/13) in group B, 75.0% (19/24) in group C, 96.6% (112/116) in group D, and 100% (27/27) in group E. A strong correlation was found between the rate of HBcAg (+) and the level of serum HBV DNA (r=0.80). This type of association also appeared between serum HBV DNA levels and HBeAg (+) (r=0.47). Of 20 CHB patients who were serum HBV DNA negative, 25% (5) were HBeAg (+), and 55% (11) were HBcAg (+), whereas 15 patients were both HBV DNA (-) and HBeAg (-), and 46.7% (7) were HBcAg (+). CONCLUSIONS: Intrahepatic HBcAg (+) in CHB patients might be more reliable in reflecting HBV replication. Determination of HBcAg (+) may have clinical significance for evaluating the efficacy of antiviral therapy and for predicting the therapeutic responses to different antiviral agents.