Dried samples (1 g) were digested to evaporate at low temperatures of 55°C on a heating plate with 3 mL concentrated nitric acid, 3 mL hydrogen fluoride, and 1 mL perchloric acid (HNO3‒HF‒HClO4). Crushed Evaporated samples were microwaved with 2 mL concentrated nitric acid and 3 mL hydrogen peroxide (HNO3‒H2O2). Digestion was performed at 120°C for 5 min, then 160°C for 5 min, and finally 180°C for 15 min. The digested product was diluted to 30 ml with ultrapure water and then stored at 4°C. The supernatant was extracted and analyzed by High Resolution Inductively Coupled Plasma Mass Spectrometry (HR‒ICP‒MS, Nu Attom, England) to determine Mn, Al, Ba, Ti, Ce, V, Sc, and Y. Urine samples (15 mL) were placed in a digestion tube and digested by microwaving with 2 mL of H2O2 and 3 mL of concentrated HNO3. The conditions of microwave digestion are the same as mentioned above. Finally, the digest was analyzed by HR‒ICP‒MS. Dried soil and dust samples (0.5 g) were digested as same as feces and food samples on a heating plate by HNO3‒HF‒HClO4. And then samples were microwaved with HNO3‒H2O2. The supernatant was analyzed for Al, Ba, Mn, Ti, and V by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP‒OES, Spectra Arcos SOP, German) which is a method for atomic emission spectroscopy analysis using a light source that generates plasma discharge through high-frequency inductive coupling and by ICP‒MS for Ce, Sc, and Y. In addition, dried soil samples from living spaces (0.5 g) were digested with the same pre-treated and analyzed by ICP‒MS for Pb, As, Cr, Cu, Ni, Cd, and Zn. The standard curve of concentration was used to determine the sample concentration was established by heavy metal standard (all standards were from The Nonferrous Metals Society of China).” Point 4. Thanks for your advice! In view of the imperfection of the method and the defects of expression, we have added and improved this part, and the modification is as follows: “Feces samples and food samples were pre-treated in the same way. The digestion process is repeated until the sample becomes sticky.
Lines 137-138: Please, modify as suggested The supernatant was then extracted and analyzed by HR‒ICP‒MS to determine Mn, Al, Ba, Ti, Ce, V, Sc, and Y, Answer: Thanks for your advice!