Quantification of Toxic Heavy Metals in Urine

We measured the levels of Cd, As, and Hg in urine. The methods used for analyzing heavy metals are detailed in our previous research.^{[4 (link)]} Cd concentration was determined using a flameless atomic absorption spectrophotometer (Hitachi Model Z-8270), which was outfitted with a Zeeman graphite furnace. Urine samples were combined with nitric acid, diluted using diammonium hydrogen phosphate and 1% Triton X-100, and then mixed thoroughly. The detection limit for Cd was 0.01 µg/L. Total As concentration in urine was analyzed using an atomic absorption spectrometer (PerkinElmer Model 5100) that incorporated a hydride generation system (PerkinElmer FIAS-400). Each urine sample was mixed with HCl, ascorbic acid, and potassium iodide (2:2:1:1); left to incubate for an hour; and then diluted with 10% HCl. The reducing agents used were 0.2% sodium borohydride and 0.5% sodium hydroxide. The mobile phase consisted of 3% HCl, with argon utilized as the carrier gas. The detection limit of the method was 0.2 µg/L. Urine Hg concentration was analyzed using the gold amalgam method with a direct Hg analyzer. After placing 100 µL of well-mixed urine in the sample container, the analysis was conducted immediately.