TY  - JOUR 
T1  - Determining plasma morphine levels using GC-MS after solid phase extraction to monitor drug levels in the postoperative period
JO  - Clinics
A1  - Santos, Veronica
A1  - López, Karin Jannet Vera
A1  - Santos, Luciana Moraes
A1  - Yonamine, Mauricio
A1  - Carmona, Maria José Carvalho
A1  - Santos, Silvia Regina Cavani Jorge
SN  - 1807-5932
UL  - 10.1590/S1807-59322008000300004
VL  - 63 
Y1  - 2008
PB  - Brasil 
ER  -