NMR evaluation of total statin content and HMG-CoA reductase inhibition in red yeast rice ( Monascus spp .) food supplements

Table 1 Results of method validation for monacolin K (lovastatin) using ¹H NMR

Parameter	Result
Investigated linear working range	5 - 100 mg/L
Limit of detection^a	6 mg/L (0.33 mg/capsule^c)
Limit of quantitation^a	13 mg/L (0.72 mg/capsule^c)
Intraday precision^b
Authentic sample^d	10%
Standard solution	7.3%
Interday precision^b
Authentic sample^d	11%
Standard solution	8.2%
Recovery	104% (at 50 mg/L) 113% (at 20 mg/L)

^a Limit of detection (LOD) and quantitation were determined by establishing a separate calibration curve near LOD. The limits were calculated from the residual standard deviation of the regression line [42]
^b Precisions were expressed as relative standard deviation (%), intraday (n = 5), interday (n = 10)
^c Based on a sample weight of 0.9 g (2 capsules) in 50 mL ethanol
^d Total statins in authentic samples