![Stability of intact chorionic gonadotropin (hCG) in serum, liquid whole blood, and dried whole-blood filter-paper spots: impact on screening for Down syndrome by measurement of free beta-hCG subunit]()
Stability of intact chorionic gonadotropin (hCG) in serum, liquid whole blood, and dried whole-blood filter-paper spots: impact on screening for Down syndrome by measurement of free beta-hCG subunitSpencer, K; Macri, J N; Carpenter, P; Anderson, R; Krantz, D A · Clinical Chemistry · 1993