Semicarbazide is a newly recognized marine pollutant and has the potential to threaten marine shellfish, the ecological equilibrium and human health. In this study, we examined the accumulation, distribution, and chemical forms of semicarbazide in scallop tissues after exposure to 10, 100, and 1000 μg/L for 30 d at 10 °C. We found a positive correlation between semicarbazide residues in the scallops and the exposure concentration (p < 0.01). Semicarbazide existed primarily in free form in all tissues while bound semicarbazide ranged from 12.1 to 32.7% and was tissue-dependent. The time for semicarbazide to reach steady-state enrichment was 25 days and the highest levels were found in the disgestive gland, followed by gills while levels in gonads and mantle were similar and were lowest in adductor muscle. The bioconcentration factor (BCF) of semicarbazide at low exposure concentrations was higher than that at high exposure concentrations. These results indicated that the scallop can uptake semicarbazide from seawater and this affects the quality and safety of these types of products when used as a food source.

In this paper, a new method of annular platform-supported headspace liquid-phase microextraction (LPME) was designed using ionic liquid as an extraction solvent, wherein extraction stability and efficiency were improved by adding an annular platform inside the extraction bottle. The ionic liquid 1-silicyl-3-benzylimidazolehexafluorophosphate was first synthesized and proved to be an excellent extraction solvent. Coupled with liquid chromatography, the proposed method was employed to analysis of polycyclic aromatic hydrocarbons (PAHs) in water and optimized in aspects of extraction temperature, extraction solvent volume, extraction time, pH, stirring rate, and salt effect of solution. The results indicated that this method showed good linearity (R² > 0.995) within 0.5 µg·L⁻¹ to 1000 µg·L⁻¹ for PAHs. The method was more suitable for extraction of volatile PAHs, with recoveries from 65.0% to 102% and quantification limits from 0.01 to 0.05 µg·L⁻¹. It has been successfully applied for detection of PAHs in seawater samples.

A method for the simultaneous determination of okadaic acid (OA) and its derivatives dinophysistoxin-1 (DTX-1), pectenotoxin-2 (PTX-2) and yesstoxin (YTX) in shellfish using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. After being extracted with methanol, the extract was cleaned-up by solid phase extraction of a Strata-X cartridge. The separation of the 4 toxins were performed on a XTerra MS C18 column (100 mm x 2.1 mm, 3.5 microm) using gradient elution of acetonitrile and water both containing ammonium formate and formic acid as eluent modifiers. The qualitative and quantitative analysis were carried out by electrospray ionization (ESI) mass spectrometry in selective reaction monitoring (SRM) mode. The OA, DTX-1 and YTX were analyzed in negative ion mode, while PTX-2 in positive ion mode. The matrix-matched external standard calibration curves were used for the quantitative analysis. The calibration curves were linear in the range of 2.0 - 200.0 microg/L for OA, DTX-1 and YTX, 1.0 - 100.0 microg/L for PTX-2, with the quantification limits of 1.0 microg/kg and 0.5 microg/kg, respectively. The average recoveries for the toxins were between 83. 1% and 105.7% with the relative standard deviations (RSD) of 3.16% - 9.29%. The proposed method is sensitive, effective and simple. It was applicable for the determination and confirmation of OA, DTX-1, PTX-2 and YTX in shellfish products. The OA, DTX-1, PTX-2 and YTX in some shellfish samples collected from Yellow Sea were found by the method.

Early detection of toxin contamination in shellfish (i.e., prior to harvest) would be of considerable advantage to fish farmers, researchers and food safety administrators. In 2004, a solid-phase adsorption toxin tracking (SPATT) technique was developed to study algal toxins in New Zealand shellfish harvesting areas. In subsequent years, the basic idea have been further developed. Using a SPATT method, an investigation into diarrhetic shellfish toxins (DSTs) was conducted over a 10.5-month period in 2012 in shellfish farming areas in Lingshan Bay (Yellow Sea, China). This paper discusses the relationship among DSTs in toxic algae, seawater and contaminated shellfish. OA, DTX1 and PTX2 toxins were found in this shellfish farming area from summer to autumn. In shellfish the maximum concentrations of OA and DTX1 were 81 and 41 ng g^–1 respectively. PTX2 was very low. The maximum levels of OA and DTX1 in seawater were 165 and 56 ng g^–1 respectively, and were detected on June, separated by a 14-day period. Shellfish had accumulated the highest levels of OA and DTX1 recorded in this study. Comparison of the variations in DST levels in seawater showed there to be about 2 weeks for administrators to warn of the potential for toxin contamination in shellfish. Further research to explore the relationship between the variables of seawater temperature, sunlight and salinity, and DSTs in shellfish may help to establish a more suitable model for forecasting DST contamination in shellfish.

Biogenic amines (BAs) are frequently detected in seafood products, wines, and fermented foods, and they pose potential risks to human health. The current study analyzed the concentrations of five common BAs in seafood, fermented food, and complementary food for infants and children (fish sausage, canned complementary food for infants containing fish and shrimp ingredients, and fish floss) in China and estimated the acute health risks of histamine (HIS) from fermented foods in Chinese consumers. Among all the samples analyzed, HIS exhibited the highest detection rate (51.9%), followed by PUT (50.1%), and the detection rate of TRY (12.5%) was the lowest. The total average concentration of the five BAs across major food categories revealed that fermented bean curd had the highest total concentration of BAs (816.8 mg/kg), followed by shrimp (383.2 mg/kg) and cheese (328.0 mg/kg). In contrast, samples of complementary food for infants and children contained the lowest concentrations of BAs; the total average concentration of the five BAs was 12.0 mg/kg. The point assessment results showed that acute dietary exposure to HIS was highest from cheese (76.2 mg/d), followed by fermented bean products (74.5 mg/d). Furthermore, the probability assessment indicated that the probability of acute health risks from exposure to HIS was 0.44% for fermented bean product consumers and 0.014% for cheese consumers, respectively. Thus, for the general consumer, the probability of acute health risks caused by HIS in seafood and fermented foods is low. However, individuals with high consumption of cheese and fermented bean products may need to be concerned.