613 / 670
5
110
110
102
107
105
102
6
105
106
105
102
108
102
Mean value
, μg/kg
108
107
101
106
105
104
RSD
ˈ
%
3.01% 2.80% 2.35% 2.33% 1.51% 1.48%
Total average
, μg/kg
105
Within-day RSD
2.25%
Between-day RSD
2.36%
Total RSD
2.97%
3.2.2 VD2 recovery study in spiked NIST SRM 1849a
NIST SRM 1849a was used as the base matrix to conduct the VD2 recovery study. The spike
levels were 12, 50, and 250 ng of VD2
᧨
corresponding to 0.12, 0.5, and 2.5
μg
VD2/100 g
reconstituted or RTF samples, respectively. Each spike level was tested 6 times continuously in 6
independent days, and 2 replicates were done within each day. The testing results in Table 6
showed that the recoveries of VD2 at all spike levels were all within 101-103%, and the
within-day and between-day RSD values were all lower than 6%.
Table 6. Recovery of VD2 in spiked NIST SRM 1849a samples
Spike
level, ng
Day
Replicates
Average RSD
Total
average
Within-day
RSD
Between-day
RSD
Total
RSD
1
2
0.12
1
101% 101% 101% 0.36%
101% 1.78%
3.01% 3.47%
2
101% 101% 101% 0.30%
3
104% 105% 105% 1.14%
4
101% 101% 101% 0.22%
5
106% 98% 102% 5.52%
6
93% 97% 95% 3.12%
0.50
1
103% 92% 97% 8.52%
103% 4.04%
4.27% 5.23%
2
99% 103% 101% 2.88%
3
101% 95% 98% 4.02%
4
105% 111% 108% 4.10%
5
108% 104% 106% 2.56%
6
103% 106% 105% 2.17%
2.50
1
107% 99% 103% 5.60%
103% 3.64%
2.25% 4.05%
2
99% 100% 100% 0.77%
3
102% 102% 102% 0.48%
4
112% 99% 106% 8.40%
5
104% 107% 106% 2.27%
6
107% 101% 104% 4.32%
3.2.3 Recovery study of VD2 and VD3 in spiked samples with different matrices
Four powder (liquid) samples with different matrices were selected to conduct the recovery
study of VD2 and VD3. The background value of VD3 in each sample was determined as the
VitD-17 (February 2016)
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