Afs 230e

The contents of K, Ca, Na, Mg, and S were estimated using inductively-coupled argon plasma atomic emission spectroscopy (ICP-AES) (Optima 5300DV, PerkinElmer, Waltham, MA, USA), and the contents of Hg, Pb, Cr, Cd, and As were estimated through atomic fluorescence spectrometry (AFS-230E, Shanghai, China). The polysaccharides were digested in HNO₃/HClO₄ (4:1, w/w) [69 (link)] and filtered through a 0.45 μm membrane, prior to detection. The fluoride content was determined, based on the GB/T 5009.18-2003 [70 (link)]. The content of chloride and polychlorinated biphenyls (PCBs) were analyzed, based on the GB/T 5009.190 (China National Food Standard – Seafood). In the case of S4 (Marinova fucoidan), some heavy metal testing was done by a third-party laboratory (AsureQuality Ltd., Auckland, New Zealand), using inductively-coupled argon plasma mass spectroscopy (ICP-MS).

Eleven heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, Fe, and Sn) were measured from all the fugitive dust samples. Following the procedure used by Liu et al. [6 (link)], each sieved sample (0.2 g) was digested with HCl-HNO₃-HF-HCLO₄. Then, an atomic fluorescence spectrophotometer (AFS, AFS-230E) and inductively coupled plasma source-mass spectrometer (Perkin–Elmer, Elan 9000) were used to measure all the chemical elements in the digested solution. For the analyses, guaranteed reagents with high purity grades were used to avoid contamination of the samples [12 (link)]. To control the quality, a national standard one-level soil sample (GSS-23) was also analyzed with the fugitive dust samples. The recovery rate of each element was between 91.2% and 108.2%. The results of the sample duplicates (10%), the national standard samples, and the method blanks showed that the relative double difference was less than 10%. Moreover, the concentration of the target heavy metal elements in the procedural blanks was below the limit of detection. All the test results conformed to monitoring requirements.