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DOI:
http://dx.doi.org/10.5740/jaoacint.12-399J. AOAC Int
. (future issue)
Posted: February 17, 2016
Table 2015.18A. ICP calibration standards from stock reagent salts for citrate–EDTA-soluble P
and K
Standard
ID
Volume,
mL
Citrate,
mL
Stock 1
,
mL
a
Stock 2,
mL
b
P concn,
µg/mL
P
2
O
5
,
µg/mL
P
2
O
5
solution, %
P
2
O
5
fertilizer, %
K concn,
µg/mL
K
2
O,
µg/mL
K
2
O
solution, %
K
2
O
fertilizer, %
Blank
1000
400
0
0
0
0
0
0
0
0
0
0
1
250
100
10 of Std 7
NA
12
27.5
0.00275
1.4
15.15
18.25
0.00182
0.9
2
250
100
20 of Std 7
NA
24
55
0.00550
2.7
30.3
36.5
0.00365
1.8
3
250
100
5
NA
50
115
0.01146
5.7
63.1
76
0.00760
3.8
4
250
100
10
NA
100
229
0.02291
11.5
126
152
0.01521
7.6
5
250
100
15
NA
150
344
0.03437
17.2
189
228
0.02281
11.4
6
250
100
22
c
NA
220
504
0.05041
25.2
278
335
0.03345
16.7
7
250
100
30
NA
300
687
0.06874
34.4
379
456
0.04562
22.8
8
250
100
40
NA
400
917
0.09165
45.8
505
608
0.06083
30.4
9
250
100
50
NA
500
1146
0.11457
57.3
631
760
0.07603
38
10
250
100
NA
25
NA
NA
NA
NA
747
900
0.08998
45
11
250
100
NA
30
NA
NA
NA
NA
897
1081
0.10805
54
12
250
100
NA
35
NA
NA
NA
NA
1046
1260
0.12600
63
a
Stock 1 = 2500 μg/mL P stock standard = 2.7461 g potassium dihydrogen phosphate (KH
2
PO
4
)/250 mL prepared in deionized water.
Also, 10 of Std 7 represents a serial dilution from another standard, meaning take 10 mL from standard 7.
b
Stock 2 = 7472 μg/mL K stock standard = 3.5615 g potassium chloride or 4.8299 g potassium nitrate/250 mL in deionized water.
c
22 mL can be achieved by using a 15 mL and a 7 mL class A pipet or equivalent combination.
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