IS 3025 (Part 41): Method of Sampling and Test (Physical and Chemical) for Water and Wastewater, Part 41: Cadmium (First Revision)

9 Pages·1992·1.2 MB·English

by  Bureau of Indian Standards (BIS)

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IS 3025 (Part 41) (1992, Reaffirmed 2003): Method of
Sampling and Test (Physical and Chemical) for Water and
Wastewater, Part 41: Cadmium (First Revision). ICS
13.060.50
“!ान $ एक न’ भारत का +नम-ण”
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“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै”
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IS 3025 (Part 41) : 1992
(Reaffirmed 2003)
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Indian Standard
METHODS OF SAMPLING AND TEST
(PHYSICAL AND CHEMICAL) FOR WATER
AND WASTEWATER
PART 41 CADMIUM
( First Revision)
Fourth Reprint MAY 2008
UDC 628.11.3 : 543 [ 546.48 ]
© BIS 1992
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
September 1992 Price Group 3
Environmental Protection Sectional Committee, CHO 012
FOREWORD
This Indian Standard ( First Revision) was adopted by the Bureau of Indian Standards, after the
draft finalized by the Environmental Protection Sectional Committee had been approved
by the Chemical Division Council.
Cadmium is highly toxic and has been implicated in some cases of poisoning through food.
Minute quantities of cadmium are suspected of being responsi ble for adverse changes in arteries
of human kidneys. Cadmium may enter water as a result of industrial discharges or the deterio
ration of galvanized water supply pipe. Desirable limit for cadmium in drinking water is 0·01
mg/l beyond which the water becomes toxic and no relaxation of this limit is allowed. The
test for cadmium is, therefore, essentia1.
In the preparation of this standard, considerable assistance has been derived from American
Society for Testing and Materials ( ASTM Annual Book Section 11, 1983 ).
In reporting the results of a test or analysis made in accordance with this standard, if the final
value, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2 : 1960
'Rules for rounding off numerical values ( revised),.
IS 3025 ( Part 41 ) : 1992
IndiaJl Standard
METHODS OF SAMPLING AND TEST
( PHYSICAL AND CHEMICAL) FOR WATER
A"ND WASTEWATER
PART 41 CADMIUM
( First Revision)
1 SCOPE nitric acid (2 tnl of AR grade nitric acid to
1 litre just to bring down the pH below 2 ).
1.1 This standard· 'prescribes the following
Unacidified samples should be analysed on the
three methods for determination of cadmium:
same day while the acidified samples may be
a) Atomic absorption method ( direct ), stored for a few days in a refrigerator.
b) Atomic absorption method (chelation
, and extraction), and '
c) Differential pulse anodic ~tripping 4.1 Unless specified otherwise, pure chemicals
voltammetry. shall be used.
1.2 The choice of the method depends upon NOTE - 'Pure chemicals' shall mean chemicals
that do not contain impurities which affect the
the concentration range and interference
results of analysis.
levels. Determination using atomic absorption
method can be done either directlv or by 4.2 Double di stilled water with a specific
chelation and extraction prior to' atomic conductivity less than 1 p.sjcm shall be used
absorption spectrophotometer determination, for preparing the standard and reagent
solutions.
2 REFERENCES
The following Indian Standards are neces')ary 5 ATOl\UC ABSORPTION METHOD
adjuncts to this standards: (DIRECT)
IS No. Title
5.1 Principle
3025 tv1ethods 0 f sampling and test
( Part 1 ) : 1986 (physical and chemical) for 'T't...~ ~~..l_: ........ ".,.,. .. +~ ... + n.~ +l..", " ............. 1"";" r!~+~_
J.ll~ ",a.UllllUlU "'\.'U.~"'l.lL V.I. LU", "(;1.11.11'1"'.1" U"'~"'l-
water and. wastewater: Part 1 mined by directly aspirating the sample into
Sampling the flame of an atomic absorption spectropho
tometer. The absorbance is measured at
7022 Glossary of terms relating to
228'8 nm using a cadmium hollow-cathode
( Part 1 ) : 1973 water, sewage and industrial
lamp. Thi; method is applicable in the con
effluents: Part 1
centration range of 0·05 to 2 mgjl. However,
7022 " Glossary of terms relating to the concentration range will vary with the
( Part 2 ) : 1979 water, sewage and industrial sensitivity of the instrument used.
effluents: Part 2
5.2 Interferences
3 SAMPLING AND PRESERVATION
Nickel, lead, copper zinc, cobalt and chromium
The sampling and storage shall be done as
do not interfere up to 10 mg/l. Alkali and
prescribed in IS 3025 (Part 1 ): 1986. The
a1kaline earth metals can be tolerated up to
sample bottles should be cleaned thoroughly
5000 mgjl. Ir.on does not interfere up to
with dilute nitri c acid (6 N) prior to the
4000 mgjl.
final rinRing with water. The water samples
should be collected and stored for 24 h prefer
5.3 Apparatus
ably in polypropylene or chemically resistant
glass containers. Por preservation, the 5.3.1 Atomic absorption spectrophotometer
samples should be acidified with concentrated with air-acetylene flame.
1
109 Deptt" of SIS/Z008
IS 3025 ( Part 41 ) : 1992
5.3.2 Cadmium hollow-cathode lamp or multi 6 ATOMIC ABSORPTION l\lETHOD
element hollow~cathode lamp for use at ( CHELATION AND EXTRACTION)
228·8 nm.
6.1 Principle
5.4 Reagents
Cadmium is chelated with pyrrolidine dithio
5.4.1 Hydrochloric Acid - Concentrated. ?arbamic acid and extracted with methyl
Isobutyl ketone (MIBK). The extract is
5.4.2 Nitric Acid - Concentrated.
treated with hot nitric acid after evaporating
6.4.3 Nitric Acid - Diluted ( 1 : 499 ). to dryness, then dissolved in hydrochloric acid
~nd dilute.d with water. An aliquot is aspirated
6.4.4 Cadmium Solutions Into the aIr-acetylene flame of the spectropho
tometer. For total recoverable cadmium an
5.4.4.1 Stock cadmium solution acid digestion procedure is carried out pri~r to
aspiration of the sample.
Dissolve 1-0 g of pure cadmium f!1e~al in. mini
mum quantity of concentrated mtnc aCId and This method is applicable in the concentration
dilute to 1 litre with distilled water (1 ml= range of 5 to 200 p.g/l cadmium.
1 mg of Cd ).
6.2 Interferences - Same as in 5.2.
5.4.4.2 Standard cadmium solution
6.3 Apparatus
Add 1 ml of concentrated nitric acid to 100 ml
6.3.1 Same as in 5.3.
of the cadmium stock solution (5.4.4.1) and
dilute to 1 litre with distilled water. 6.4 Reagents
6.4.1 Hydrochloric Acid - Concentrated.
5.5 Procedure
6.4.2 Nitric Acid - Concentrated.
5.S.1 To 100 ml portion of the acidified sample
add 5 ml of concentrated hydrochloric acid 6.4.3 Dilute Nitric Acid - 1 : 499.
and evaporate to 20 mI. Cool and filter the
6.4.4 Cadmium Solutions
sample and make up to 100 ml in a standard
flask. If only dissolved cadmium is to be
6.4.4.1 Stock cadmium solution - Prepare as
determined, fiiter 100 mi of the sample and in 5.4.4.1.
acidify with 0·1 ml of concentrated hy~rochlo­
ric acid. Aspirate the samp le solutIOn and 6.4.4.2 Intermediate cadmium solution
measure the absorbance at 228-8 nm. A"pirate
nitric acid (1: 499) prior to sample Add 1 ml of concentrated nitric acid to 50 ml
of stock solution and dilute to 1 litre with
aspira tion.
water. 1 ml =50 p.g of cadmium.
S.S.2 PreDare a reagent blank and a series of
6.4.4.3 Standard cadmium soiuiion
100 m} standards containing 0-0, 0-05,0'1,0-5,
1 and 2 mg/l of cadmium by diluting a suita To 10 ml of cadmium intermediate solution add
ble volume of the standard solution with 1 roI of concentrated nitric acid and dilute to
dilute nitric acid and repeat as above. Aspirate 1 litre with water. 1 ml = 0-5 p.g of cadmium.
the solutions and measure the absorbance.
6.4.5 Sodium Hydroxide Solution
5.6 Calculation
Dissolve 100 g of sodium hydroxide in water
Construct a standard calibration graph by and dilute to 1 litre.
plotting the absorbance versus cadmium con~
6.4.6 Methyl Isobutyl Ketone (J.1IBK)
centration (rug/I) of each standard. Read
Reagent grade.
the concentration of the sample from the
graph.
For trace analysis purify MIBK by redistilla
M tion or by sub-boiling distillation.
Cadmium, mg/l = V x 1 000
6.4.6.1 Water saturated MIBK
where
Mix one part of purified MIBK wi th one part
.IT.t,[ = mass tlf cadmium in mg In the of water in a separatory funneL Shake 30
sample, and
times and let separate. Discard aqueous layer.
V = volume of the sample in ml. Save IYHBK layer.
2
IS 3025 ( Part 41 ) : 1992
6.4.7 Bromophenol Blue Indicator Solution standards in the same manner as the sample.
Aspirate the MIBK extracts and measure the
Dissolve 0·1 g of bromophenol blue in 100 ml absorbance.
of 50 percent ethanol or isopropanol.
6.6 Calculation
6.4.S Pyrrolidine Dithiocarbamic Acid - Methyl
isobutyl Ketone ( MIBK ) Reagent 6.6.1 Construct a standard calibration graph
by plotting the absorbance versus the con
~1ix 36 ml of pyrrolidine with 1 litre of MIBK. centration (p.gj 1) of cadmium. Read the
Cool the solution and add 30 ml of carbon
concentration of the sample from the graph.
disulphide in small fractions with continuous
stirring. Dilute with 2 litres of MIBK. Store Cadmium, p,g/l = ~ x 1000
in a cool and dark place. The reagent so
prepared is stable for at least six months.
where
NO.TE - As components of this mixture are highly M = mass of cadmium in p.g in the
tOXIC and flammable, prepare and use in a sample, and
fumchood.
V = vo lume of sample in mI.
6.S Procedu.re
7 DIFFERENTIAL PULSE ANODIC
6.5.1 If total recoverable cadmium is to be STRIPPING VOLTAMMETRY
determined, add 5 ml of concentrated hydro~
chloric acid and evaporate the solution to 15 to 7.1 Principle
20 ml. Cool and filter the sample through acid
Cadmium is deposited on a hanging mercury
washed filter paper. Make up to 100 ml in a
vol~metric flask. Add 2 drops of bromophenol drop electrode at a negative potential of -0·8 V
versus saturated calomel electrode. Then the
. blue indicator solution and mix. Adjust the
cadmium is stripped back into the solution by
pH by adding sodium hydroxide solution till a
applying a positive potential scan. The anodic
blue colour persists. Add dilute hydrochloric
c.urrent peak which.is measured is representa
acid ( 1 : 49 ) drop by drop until the colour
tIve of the cadmmm concentration in the
just disappears. Then add 2·5 ml of dilute
sample. For total dissolved cadmium the
hydrochloric acid to bring the pH to 2'3 to 2·5.
sample is filtered through Whatman No. 40
Add 10 ml of pyrrolidine ditbiocarbamic
acid - MIBK reagent and shake well. After the filt~r paper p~ior to .acidifi~ai.ion and anaiysis.
ph~ses separate, ~ollect the MIBK phase by ThIS method IS apphcable III the concentration
takmg care to avoId any trace of water in the range of O.l~ 100 p.g/l.
flask. Repeat the extraction twice with 6 to
7.2 Interferences
7 ml ofMIBK till the MIBK layer becomes
co lourless. Combine the extracts. Aspirate
Selenium interferes when its concentration
the organic extract directly into the flame
e~c~~eds 50 p,~( i. ~~is. ~a? be overcome by
(z'~roing instrument 011 a ,vater saturated aaamg ascorOlC aCla wllIcn reduces seienium
MIBK blank) and record absorbance. To
( IV ) to selenium metal. Iron ( III ) interferes
avoid problems associated with instability of
when present at ievels greater than cadmium.
extracted metal complexes determine immedia
However, this can be overcome by warming the
tely after extraction. Evaporate the solution
solution with hydroxylamine. The presence of
just to Jryness and dissolve the residue by
~ny other neighbouring stripping peaks which
dropwise addition of 2 ml of concentrated
lS less than 100 mV from that of cadmium will
nitric acid by holding the beaker at an angle.
interfere.
Again evaporate to dryness and add 2 ml of
hydrochloric acid (1: 2) and heat for 1 7.3 Apparatus
minute. Cool and make up the solution in a
10 ml standard flask. Aspirate the sample and 7.3.1 Polarographic instrumentation capable
of performing differential pulse work.
measure the absorbance.
7.3.2 Hanging Mercury Drop Electrode
NOTE _ Evaporation should be carried out at low
beat using hot plate to avoid any losses due to
7.3.3 Platinum Counter Electrode
vo]atilization of cadmium.
7.3.4 Saturated Calomel Reference Electrode
6.5.2 Prepare a reagent blank and a series of
(\ .f.... :..'.r..',ATJl \)
sufficient standards containing 0, 10, 20, 50,
100, 200 ILgj 1 of cadmium by diluting a suitable 7.3.5 Magnetic Stirrer Control Unit, Stirring
volume of the standar<J solution. Treat the Bar
3
IS 3025 ( Part 41 ) : 1992
7.4 Reagents cells by soaking them overnight in concentra
ted nitric acid and rinsing them thoroughly with
7.4.1 Hydrochloric Acid - Concentrated; spec water. Add 1 ml of hydroxylamine sol ution.
trograde. Warm for 15 minutes to reduce the ferric
concentration. Add 1 ml of ascorbic acid.
7.4.2 Nitric Acid - Concentrated; spectro Evaporate gently. Cool and make up to 100
grade. ml. If total dissol ved cadmium alone is to be
determined, the sample should be filtered
7.4.3 Hydroxylamine Solution -- 100 g! I through 0·45 fLm membrane filter paper. For
total recoverable cadmium, digest the sample
Dissolve 5 g of hydroxylamine hydrochloride
with 3 nil each of concentrated hydrochloric
in 50 ml of water.
acid and nitric acid. Evaporate the solution to
15 to 20 ml. Cool and make up to 100 ml in a
7.4.4 Dilute Nitric Acid - 1 : 1
standard flask. Take 10 ml of the sample in
the polarographic cell and de-aerate for 15
7.4.5 Ascorbic Acid - 100 mg/l
minutes. The cell should be covered with
nitrogen gas during the experiment (Fig. 2 ).
Dissolve 10 g of L-ascorbic acid in 100 rol of
water.
Generate a new droplet of mercury and put the
7.4.6 Cadmium Solutions stirrer on. Connect the cell and deposit at
- 0·80 V versus saturated calomel electrode
7.4.6.1 Stock cadmium solution for 3 minutes, Stop the stirrer and wait for
30 seconds. Start the anodic scan with the
Dissolve 1,0 of pure cadmium metal by warD?- following settings:
ing with 10 ml of conce~t~ated, hydro,chIonc
acid and 30 ml of 1 : 1 mtnc aCid. DIlute to
Initial potential - 0·80 V vs saturated
1 litre with distilled water. calomel electrOde
(SeE)
7.4.6.2 Intermediate cadmium solution
Scan rate 5 mV
Add 1 ml of concentrated ni tr ic acid to 10 ml Scan direction ( + )
of stock solution and dilute to 1 Ii tre with Modulation amplitude 25 mV
U,J!;". ..,. :U11U,.~,.U,J .V..V ~a .L.. !,;,; ;I. Current range l-IO/-,A
Droptime 5 sec
7.4.6.3 Standard cadmium solution
Display direction (- )
Dilute j 0 mI of cadmium intermediate so lution Low pass filter Off position
to 100 ml with distilled Wetter. pj epare daily
Mode Differential pulse
for use. 1 ml = 10 fLg of cadmium.
Scan range 0·75 V
7.4.7 Amalgamated Zinc
Measure the current peak height (II). Add
Cover 10 g of granular zinc with water and add 20 iLl of standard cadmium solution and de
2 drops of concentrated hydrochloric acid. aerate for 5 minutes. Repeat as above.
Then add 5 to 8 drops of mercury with conti Measure the current peak height ( 12 ).
nuous shaking.
7.6 Calculation
7.4.8 Purified Nitrogen
Boil 2 g of ammonium meta vanadate with 25 C a dmm· m, p.g /1 = 12 V I+I V( 1Cs-tdII ) V X 1 000
ml of concentrated hydrochloric acid. Dilute 2
to 250 ml and transfer to the scrubber. Add II = current peak height for sample,
10 to 15 g of amalgamated zinc. Pass nitrogen
12 = current peak height for sample and
gas through the scrubber for removal of traces
standard,
of oxygen and through distilled water for
washing any traces "of scrubber chemicals v = volume of standard added ( 20 fLl ),
( Fig. 1 ) V = volume of the sample solution in ml,
and
7.5 Procedure
Cstd = concentration of the standard solu
Clean all the glassware and the voltammetric tion added.
4
IS 3025 ( Part 41 ) : 1992
,-----
t-h
AMM. META
VANADATE &: Hel
WATER
AMALGAMATED
ZINC ---
FIG. 1 SCRUBBER ASSBMBLY FOR NITROGEN PURIFICATION
N 2 GAS
~ Pi COUNTER
ELECTRODE
seE REFERENCE
~LECTRODE
HMDE.WORKING
ELECTRODE
STIRRER BAR
FIG. 2 VOLTAMMBTlUC CELL ASSEMBLY
5
109 Dcptt. of BIS/2008