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H.
Calculations
(a) Calculate silver nitrate concentration (SNC) in mol/L for system suitability verification and
report to 4 decimal places:
SNC (mol/L) =
1
5.844
×
2 3
×
1
1
×
1 10
where
1
= weight of sodium chloride standard solution (mg);
2
= weight of sodium chloride
used to prepare the standard solution (mg);
3
= total weight of prepared sodium chloride
standard solution (mg);
1
= AgNO
3
consumption volume up to titration endpoint (mL); 5.844 =
sodium chloride weight in μg corresponding to 1mL of 0.1mol/L AgNO
3
; and 10 = mass
conversion from titer to the concentration of titrant.
(b) Calculate chloride content in sample (CL) and report to 3 significant digits:
CL (mg/100g) =
35.5× ×
2
× ×100
4
where
4
= sample weight (g);
c
= certified concentration of silver nitrate titrant (mol/L);
2
=
AgNO
3
consumption volume up to titration endpoint (mL); = dilution factor; 35.5 = chloride
weight in μg corresponding to 1mL of 1mol/L AgNO
3
; and 100 = mass conversion to mg/100 g.
References:
J. AOAC Int
. (future issue)
AOAC SMPR 2014.015
J. AOAC Int
.
98
, 1079(2015)
Posted: October 1, 2015
Candidates for 2016 Method of the Year
88