Blood Samples (plasma and Red Blood Cells)

Abstract Fasting 10 ml venous blood samples were collected from 8,280 individuals in mainland China in trace-mineral-free heparinized vacutainers, which were placed on ice in light-free vacuum jars. Samples were transported to the county laboratory within about four hours of the last blood draw of the day. Upon arrival at the county laboratory, blood samples were immediately separated into three fractions: 1.3 ml of packed red blood cells (RBCs), washed three times with saline, haemolyzed with 3 ml preservative buffer, then mixed and frozen.