Table 1: The results of precision, accuracy, and recovery studies for morphine and codeine in human urine .

CompoundConcentrationRSD (%)RE (%)Recovery (%)
(ng/mL)IntradayInterdayIntradayInterday

Morphine504.38.2−0.3−6.586.1
2004.47.4−5.2−10.175.5
16005.39.3−6.95.780.2

Codeine 5010.513.0 8.5−7.378.9
20011.49.8−3.9−12.879.7
16005.212.9−9.9−8.286.8