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J
audzems
:
J
ournal of
AOAC I
nternational
V
ol
.
99, N
o
.
4, 2016
1113
Chloride in Milk, Milk Powder, Whey Powder, Infant
Formula, and Adult Nutritionals by Potentiometric Titration
Method: First Action 2016.03
G
reg
J
audzems
Nestlé USA, Inc., Quality Assurance Center, Chemistry Technical Services, 6625 Eiterman Rd, Dublin, OH 43017
T
ian
Y
an
and
W
an
X
in
Chinese Academy of Inspection and Quarantine Comprehensive Test Center, Beijing 100123, China
S
takeholder
P
anel on
I
nfant
F
ormula
and
A
dult
N
utritionals
E
xpert
R
eview
P
anel
for
SPIFAN N
utrient
M
ethods
Darryl Sullivan (Chair)
, Covance Laboratories
John Austad
, Covance Laboratories
Sneh Bhandari
, Silliker Laboratories
Esther Campos-Gimenez
, Nestlé
Adrienne McMahon
, Nestlé
Scott Christiansen
, Perrigo
Hans Cruijsen
, FrieslandCampina
Wil van Loon
, FrieslandCampina
Jon DeVries
, General Mills/Medallion Laboratories
Brendon Gill
, Fonterra
Don Gilliland
, Abbott Nutrition
Karen Schimpf
, Abbott Nutrition
Min Huang
, Frontage Laboratories
Estela Kneeteman
, National Institute of Industrial Technology
Bill Mindak
, U.S. Food and Drug Administration
Maria Ofitserova
, Pickering Laboratory
Shay Phillips
, Mead Johnson
Guenther Raffler
, Central Laboratories Friedrichsdorf–
Eurofins
Kate Rimmer
, National Institute of Standards and Technology
Melissa Phillips
, National Institute of Standards and
Technology
David Woollard
, Hill Laboratory
Jinchuan Yang
, Waters Corp.
Introduction
The presented method is a combination of AOAC First
Action methods
2015.07
(1) and
2015.08
(2). As both methods
were reviewed by the Expert Review Panel as equivalent, the
authors were asked to combine the methods into one method.
This combined method maintains the performance requirements
cited in each separate method single-laboratory validation
and therefore meets the
Standard Method Performance
Requirements
(3).
AOAC Official Method 2016.03
Chloride in Milk, Milk Powder, Whey Powder, Infant
Formula, and Adult Nutritionals
Potentiometric Titration Method
First Action 2016
(Applicable to the determination of chloride in milk, milk
powder, whey powder, infant formula, and adult nutritionals
by potentiometry, with an analytical range of 0.35–1060 mg
chloride/100 g reconstituted product or ready-to-feed (RTF)
liquids).
Caution
: Consult Material Safety Data Sheets for all
substances that are required and considered
hazardous. Follow all laboratory safety precautions
and wear proper personal protective equipment.
A. Principle
Reconstitute powder samples by dissolving 25 g powder
sample in 200 g warm water (40°C); RTF products are ready
to use as they are. Precipitate proteins by adding precipitation
solutions I and II, and then centrifuge. Acidify the supernatant
with nitric acid solution. Titrate chloride ions against
standardized silver nitrate solution (0.1 M), potentiometrically
using a silver electrode to detect the end point.
B. Apparatus
Common laboratory equipment and, in particular, the
following:
(a)
Analytical balance
.—Precision to 0.1 mg.
(b)
Centrifuge
.—Tabletop with rotor for 50 mL conical
tubes, capable of operating at ≥12000 ×
g
.
(c)
Centrifuge tubes
.—50 mL, conical, polypropylene.
(d)
Pipets
.—1, 10, 20, 50, and 100 mL, Class A glass
volumetric or automatic (Eppendorf or equivalent).
Submitted for publication April 2016.
Adopted as a First Action Official Method by the Expert Review
Panel on SPIFAN Nutrient Methods.
Approved on: March 16, 2016.
Corresponding author’s e-mail:
greg.jaudzems@us.nestle.comDOI: 10.5740/jaoacint.16-0123
OFFICIAL METHODS
6