ENFORCE25906

• Permit No: M1988112
• IBM Index Class Name: Enforcement
• Doc Date: 5/4/1992
• Doc Name: TRACE DETERMINATION AND SPECIATION OF CYANIDE ION BY ATOMIC ABSORPTION SPECTROSCOPY
• Media Type: D
• Archive: No

RDR TECHIJLLG~~IE:; IhJi_. TEL~.~O'-79~~-5e3~ Miry 04 92 5~ ~' No . 004 P.07
• ,d • . ANALYTICAL CHEM~Y, VOL. 83, N0. ,APRIL 1, 1891 • 807
. able V. 6ehavlor of 811vsr during Analysts
analysts for silver, pg/L A<
sample Ag canto, pg/L untreated sample Rltered stabilized° free cyanide CNAT Wtal cyanide
AgNO~ 60 62 0 0 0 ~ 0
AgtCN)y 60 48 6y 63 4 47
ApNOr* 60
AgICN)~ b0 107 49 6] 6 4B
°Filtcred with O.d6•ym pare also fil ler, stabilised et pH = 12. ~ _

Tahlo Vl. Sample Compo^itivn of Analyta Mixturc^
composition, µg/L (daR nod catogerical cnmpaeitlanl _ _~

zinc chromium
silver cyanide
ferrous
ferric
obolt
cyanide cyanide cyanide (week 60%J cyanide eyanlda c snide thio•
sample (free 100%I Ifree 100%J Iweek 100%1 (CNATC b0%1 ICNATC 100%] (CNATC 100%1 (CN C 100%J cyenate
3 40 200 0 0 400 100 0 0
~' 2 40 40 40 40 40 0
~ 40 40
3 0 0 20 0 20 100 20 0
4 200 400 0 0 0 0 20D 40D
b 10 40 20 0 40 100 0 0
a o 0 0 o zoo loD 20D o
7 40 20 0 20 40 0 40 0
8 100 0 0 0 100 100 0 400
quired for the CNATC and total cyanide procedures, aincv
silver liberated during those procedures is eliminated through
the inherent precipitation and filtration steps already in-
torporated in those procedures. Table V illustrates thasa
points.
Analysis of Sample Miaturoe. In order to study the
recovery of vnrioue cyanide species using the silver probe
reaction procedures, several synthetic samples were prepared.
These ssrnples, containing both free end motel complexes of
cyanide, were prepared in a distilled water matrix. The
composition of the samples ie listed in Table V[. Por each
sample, a enlculated concentration for tree, CNATC, end total
cyanide has Assn determined with the categorical dafinitione.
Tahlo VII lists Lheae values, along with the concentrations
measured by the throe categorical procedures. The results
indicate that, even in aamplea of varied composition, the
enncontration of each categorical division can be determined
with excellent agreement to defined concentrations. Of the
three cetegorics, the best acturacy wee Found with rho total
cyanide division, which has a relative standard deviation
(RSD) of 0.04. This accuracy is similar to that of direct atomic
absorpl.iun analyses, indicating only minimal error is intra•
doted by the indirect analysis. Both the free cyanide and
CNATC dotarrninations have RSll's of npprnsimatoly 0.10.
The free cyanide measurement is slightly elevated. while the
CNATC measurement has a slight negative deviation from
the defined concentration, The bias found in the CNATC
measuremanis can be nt least partially attributed to the
presence of free cyanide impurities ;n the metal cyanide so•
lotions. These ere present both as reagent impurities end as
pllot.odiasociation products from Inbnratnry lighting. Such
a conclusion is supported by rho results. Such impurities
would, o[ course, elevate the tree cyanide concentration while
reducing the CNATC measurement by allowing ndditional
cyanide Lu be removed through oxidation. Such errors are,
lwwever, only minor, es indicated by the overall RSD of 0.082
for all three categories.
Limits of Detection. Given the appropriate cortditiona,
the Ag filter provides complete reaction of cyanide anplytes
with the silver metal. This is true fur all threw categorical
procedures. As the silver-cyanide reaction indicates, there
is over a 2:1 mass Increae when the silver atom, rather then
Table VIf. Categorical Cyanide Detcr inatioa of Aoslyte
Mlxtura^
free cyanide total cyanide
concn° CNATC rnn n° concn°
sample defined mewed defined me ed defined mewed
1 0.240 0.263 0.600 0.4 3 0.740 0.749
2 0.080 0.078 O.LDO 0. d 0.240 0.228
9 0.000 0.002 0.140 0.1 7 0.160 O.l4B
4 0.800 0.561 D.200 O.l 9 0.800 0.800
6 0.080 O.OB2 O.L40 0.1 4 0.240 0.231
8 0.000 0.029 0.500 0. 3 O.bOD 0.462
7 0.060 0.066 0.090 0. 1 0.180 0.188
8 0.100 0.119 0.200 0.10 0.300 0.306
•All concentrations in ug/mL.
cyanide ion, becomes the analytic ape ies. This is coupled
with the foot that silver is one element 'ch has en artremoly
low litnit o[ detection by atomic absorp ion spectroscopy. As
a result, the detection limit for the situ r AAS system, for ell
species of cyanide, using flame atomized n AAS is 0.002 mg/L.
$y using carbon rod atomization, th t limit is reduced to
0.00006 mg/L. Both of these tousle a e well below those of
standard cyanide measurement meth a and below the EPA
water quality criterion.
CONCLUSION
In tl»s paper, what might be consid red classical reaction
chemistry hew been utilized in fl unique vatem to provide the
basis of an ultratrace cyanide detecti n method. Straight-
forward reaction kinetics and well-d fined photochemical
ligend dissociation reactions have bee utilized to provide a
means of species differentiation. T a result ie a simple
analytical system that can intertaco to ny atomic absorption
spectrometer to provide quentitativo d to nn coneentretione
of cyenida low enough to be useful. 9'he current system,
coating lace to construct then the glass vote required to do a
single cyanide-distillation, requhes ve little supervision and
ten easily be adppted for eutomatior . The capability of
quickly and simply determining all our defined cyanide
categories may provide the needed in ormntion for the fm-
pruved management of tyanide•pnllu d waters.