-
231
HEAVY METALS
重金属
This test is
provided to demonstrate that the content of
metallic impurities that are colored by
sulfide ion, under the specified test
conditions, does not exceed the Heavy metals limit
specified
in
the
individual
monograph
in
percentage
(by
weight)
of
lead
in
the
test
substance,
as
determined by concomitant visual
comparison (see Visual Comparison in the section
Procedure
under
Spectrophotometry
and
Light-
Scattering
（
851) with
a
control
prepared
from
a
Standard
Lead
Solution.
[NOTE
—
Substances
that
typically
will
respond
to
this
test
are
lead,
mercury,
bismuth, arsenic, antimony, tin,
cadmium, silver, copper, and molybdenum. ]
本检验是用来测定与硫化物离子作用显色的金属杂质含量，
不得超过专论中规定
的重金属限度供试品中铅的百分比
溶液配制的对照进行视觉比较来得出结论的
的视觉比较）。
铜和钼。
]
Determine the amount of heavy metals by
Method I, unless otherwise specified in the
individual
monograph.
specified
test
preparations under the test conditions
specified for Method I, or for substances that, by
virtue of
their complex nature,
interfere with the precipitation of metals by
sulfide ion, or for fixed and
volatile
oils.
Method I nor Method II
can be used.
除各论另有规定外，用方法
的检测
；
方法
或者是固化物和挥发性油状物的检测；方法
用时的检测
Special Reagents
Lead Nitrate Stock
Solution
been added 1 mL of nitric acid,
then dilute with water to 1000 mL. Prepare and
store this solution
in glass containers
free from soluble lead salts.
Standard
Lead Solution
water to 100.0 mL. Each mL
of Standard Lead Solution contains the equivalent
of 10 ?g of lead. A
comparison
substance being tested contains the
equivalent of 1 part of lead per million parts of
substance
being tested.
硝酸铅贮
备液：
mL
。于不含可溶铅盐的玻璃容器中配制和贮存该溶液。
标准铅溶液：使用当天，取硝酸铅贮备液
溶液相当于
[
注意：与本检验起反应的代表性物质为铅、汞、铋、砷、锑、锡、镉、银、
< br>Method
I
is
used
for
substances
conditions.
Method
II
Method
III,
a
wet-
digestion
I
测定重金属含量。方法
II
用于方法
I
规定条件下的
非澄清、
—
Dissolve
159.8 mg of lead nitrate in 100 mL of water to
which has
—
On the day of
use, dilute 10.0 mL of Lead Nitrate Stock Solution
with
prepared
on
the
取硝酸铅
159.8
mg
g
的铅。对照溶液用
（重量
比）
（参看分光光度法和光散射法
that
yield
clear,
used
for
substances
method,
is
used <
/p>
I
用于规定条件下的澄清、无色供试品
无
色供试品，
III
湿法消解，用于方法一与方法二均不适合使<
/p>
basis
of
100
?L
of
专用试剂
1
mL
的水
10.0mL
，加水稀释至
L
标准铅溶液，
在规定检验条件下，
其检测结果
，
该检验是通过与标准铅
<851><
/p>
中规程部分
colorless
preparations
under
that
do
not
yield
clear,
colorless
in
those
cases
where
自身对硫化物离子存在干扰，
Standard
Lead
Solution
per
100 mL
，
溶解，
加水稀释至
100.0mL
。每
1mL
the
g
of
1000
is
only
neither
solution
，
加已加硝酸
标准铅
10
?
100 ?
METHOD I
pH 3.5 Acetate
Buffer
—
Dissolve 25.0 g of
ammonium acetate in 25 mL of water, and add 38.0
mL
of 6 N hydrochloric acid. Adjust, if
necessary, with 6 N ammonium hydroxide or 6 N
hydrochloric
acid to a pH of 3.5,
dilute with water to 100 mL, and mix.
Standard
Preparation
—
Into a 50-mL
color-comparison tube pipet 2 mL of Standard Lead
Solution
(20
?g
of
Pb),
and
dilute
with
water
to
25
mL.
Using
a
pH
meter
or
short-
range
pH
indicator
paper
as
external
indicator,
adjust
with
1
N
acetic
acid
or
6
N
ammonium
hydroxide
to
a
pH
between 3.0 and 4.0,
dilute with water to 40 mL, and mix.
pH
3.5
醋酸盐缓冲液：取醋酸铵
25.0 g
< br>，加水
25mL
，加
6
N
盐酸
38.0
mL
，溶解。如有需
要，用
6
N
氨水或
6
N
盐酸调整
pH
为
< br>3.5
，用水稀释至
100
mL
。混匀。
标准品：用移液管取标准铅溶液
25 mL
。使用
pH
计或短范围
与
4.0
之间，用水稀释至
Test
Preparation
—
Into a 50-mL
color-comparison tube place 25 mL of the solution
prepared for
the test as directed in
the individual monograph; or, using the designated
volume of acid where
specified in the
individual monograph, dissolve in and dilute with
water to 25 mL the quantity, in
g, of
the substance to be tested, as calculated by the
formula:
in
which
L
is
the
Heavy
indicator paper as external indicator,
adjust with 1 N acetic acid or 6 N ammonium
hydroxide to a
pH between 3.0 and 4.0,
dilute with water to 40 mL, and mix.
供试
品：取按照专论中所述制备的供试液
使用指定体积的酸溶解按下列公式计算的供试品的数
量（单位
公式中，
L
是重金属限度，作
为一个百分数。使用
用
1
N
醋酸或
6
N
氨水调整
Monitor
Preparation
—
Into a third
50-mL color-comparison tube place 25 mL of a
solution
prepared as directed for Test
Preparation, and add 2.0 mL of Standard Lead
Solution. Using a pH
meter or short-
range pH indicator paper as external indicator,
adjust with 1 N acetic acid or 6 N
ammonium hydroxide to a pH between 3.0
and 4.0, dilute with water to 40 mL, and mix.
监控品：取按照供试品溶液配制方法所述制备的溶液
加标准铅溶液
2.0 mL
，
调整
pH
至
3.0
与
4.0
之间，用水稀释至
Procedure
—
To each of the three tubes
containing the Standard Preparation, the Test
Preparation,
and
the
Monitor
Preparation,
thioacetamide
–
glycerin
base TS, dilute with water to 50 mL, mix, allow to
stand for 2 minutes,
and view downward
over a white surface : the color of the solution
from the Test Preparation is
not darker
than that of the solution from the Standard
Preparation, and the color of the solution
from the Monitor Preparation is equal
to or darker than that of the solution from the
Standard
Preparation.
[NOTE
—
If the color of the
Monitor Preparation is lighter than that of the
Standard
Preparation, use Method II
instead of Method I for the substance being
tested. ]
步骤：在标准品、供试品和监控品中各加
甘油基底试液
1.2 mL
，用水稀释至
下观察：供试品与标准品的溶液颜色比较，不得更深；监控品与标准品的溶液颜色比较，应
2 mL
（含
20 ?
g
的铅），置
50mL
比色管中，用水稀释至
pH
试纸作为外指示剂，
用
1 N
醋酸或
6 N
氨水调整
pH
至
3.0
40 mL
，混匀。
2.0/(1000L)
metals
limit,
as
a
percentage.
Using
a
pH
meter
or
short-
range
pH
25 mL
，置
50mL
比色管中；或当专论有规定时
，
g
）并用水稀释至
25
mL
，
2.0/(1000
L
),
pH
计或短范围
pH
试
纸作为外指示剂，
pH
至
3.0
与
4.0
之间，用水稀释至
< br>40 mL
，混匀。
25 mL
，置于第三只
50mL
比色管中，
pH
计或短范围
pH
试纸作为外指示剂，
用
1
N
醋酸或
6
N
氨水
40
mL
，混匀。
add
2
mL
of
pH
3.5
Acetate
Buffer,
then
add
1.2
mL
of
pH
3.5
醋酸盐缓冲液
2
mL
，然后加硫代乙酰胺
-
50 mL
，混匀，静置
2
分钟，置一白色表面上
，自上向
使用
相当或颜色更深。
[
注意：如果监控品溶液的颜色比标准品
溶液的颜色更浅，使用方法
II
代
替方
法
I
来检测该供试品。
]
METHOD II
NOTE
—
This method
does not recover mercury.
pH 3.5 Acetate
Buffer
—
Prepare as directed
under Method I.
Standard
Preparation
—
Prepare as
directed under Method I.
注意：该方法不包含汞。
pH 3.5
醋酸盐缓冲液：按照方法
标准品：按照非方法
Test
Preparation
—
Use
formula:
供试品：使用按下公式计算的供试品的数量（单位
in
which
L
is
the
Heavy
substance to a suitable crucible, add
sufficient sulfuric acid to wet the substance, and
carefully
ignite at a low temperature
until thoroughly charred. (The crucible may be
loosely covered with a
suitable lid
during the charring.) Add to the carbonized mass 2
mL of nitric acid and 5 drops of
sulfuric acid, and heat cautiously
until white fumes no longer are evolved. Ignite,
preferably in a
muffle furnace, at 500
to 600, until the carbon is completely burned off.
Cool, add 4 mL of 6 N
hydrochloric
acid, cover, digest on a steam bath for 15
minutes, uncover, and slowly evaporate on
a steam bath to dryness. Moisten the
residue with 1 drop of hydrochloric acid, add 10
mL of hot
water, and digest for 2
minutes. Add 6 N ammonium hydroxide dropwise until
the solution is just
alkaline
to
litmus
paper,
between
3.0
and
4.0,
necessary, rinse the
crucible and the filter with 10 mL of water,
combine the filtrate and rinsing in
a
50-mL color-comparison tube, dilute with water to
40 mL, and mix.
公式中，
L
是重金属限度，以百分量计。取准确称量的一定量被测样品至合适的坩埚中，加
适量硫酸以润湿样品，低温小心灼烧直至完全碳化。
适的盖子，但不要盖得太严实。
至硫酸烟雾挥发完全。于马费炉中灼烧，温度为
入
< br>4mL
6N
盐酸，盖上盖子，在蒸汽浴中水解
用
1
滴盐酸润湿残渣，加
（用石蕊试纸检查）
试纸作外部指示剂。如果有需要，可过滤，用
至
50mL
比色管中，用水稀释至
Procedure
—
To each of the
tubes containing the Standard Preparation and the
Test Preparation,
add
2
mL
of
pH 3.5
with
water
to
50
mL,
surface
:the color of the solution from the Test
Preparation is not darker than that of the
solution
方法
II
I
所述配制。
所述配制。
a
quantity,
in
g,
of
the
substance
to
be
tested
as
calculated
by
the
2.0 / (1000L)
g
）
：
2.0/(1000L)
metals
limit,
in
percentage.
Transfer
the
weighed
quantity
of
the
dilute
with
water
to
25
mL,
and
adjust
with
1
N
acetic
acid
to
a
pH
using
short-
range
pH
indicator
paper
as
an
external
indicator.
Filter
if
（在碳化过程中，可以给坩埚盖一个合
）向已碳化的残渣中加入
2mL
硝酸和
5
滴硫酸，小
心加热直
500
～
600
°，直至碳完全燃烧。冷却，加
15
分钟，移开盖子
，于蒸汽浴中蒸发至干。
10mL
热水，水解
< br>2
分钟。滴加
6N
氢氧化铵直至
溶液刚好显碱性
用水稀释至
25mL
，
用
1N
冰乙酸调节至
< br>pH3.0
～
4.0
，
可使用短范围
pH
10mL
水洗涤坩埚和过滤器，滤液与洗液合并
40mL
，摇匀。<
/p>
Buffer,
then
add
1.2
mL
of
thioacetamide
–
glycerin
base
TS,
dilute
mix,
allow
to
stand
for
2
minutes,
and
view
downward
over
a
white
II
，
Acetate
-
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