The accuracy was conducted by recovery experiments due to the
absence of reference materials [19,20,24]. Recovery was expressed
as a percentage that was determined by comparing the responses
of a blank sample matrix in its original state to after the addition
(spiking) of a known mass of analyte that was subjected to the
entire analytical procedure. The blank sample used in this study
had a very low amount of native analyte, at less than 10% of the
amount of added analyte. Therefore, the total recovery as based on
recovery of the native plus the added analyte is used to measure of
the accuracy of the method [19,20]. Acceptable recovery depends
on a function of the concentration and the purpose of the analysis being conducted. The term pmol/l represents the number of
moles of the substance present in a defined volume of solution. The
concentration unit was converted to g/g by a multiplication of
an analyte molecular weight by its spiking concentration. The FDA
Guidelines for the validation of Chemical Methods for the Foods
Program recommends that the acceptable recovery for quantitative methods with spiking concentrations at 10 g/g is 80-115%