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Simultaneous extractive spectrophotometric determination of palladium(II)-platinum(II) or palladium(II)-gold(III) with benzyltriethylammonium ion and iodide in the presence of EDTA
MICROCHEMICAL
JOURNAL
37, 18-21 (1988)
Simultaneous Extractive Palladium(ll)-Platinum(ll) Benzyltriethylammonium
Spectrophotometric Determination or Palladium(ll)-Gold(lll) with Ion and Iodide in the Presence of EDTA
of
E . KAVLENTIS Department of Chemistry, University of Thessaloniki, Thessaloniki, Greece Received February 7, 1987; accepted September 14, 1987 Palladium(II), platinum(H), and gold(II1) react with benzyltriethylammonium ion and iodide in slightly acid medium to form water-insoluble colored ternary complexes stable in the presence of EDTA and extractable into MIBK. Palladium(II)-platinum(I1) and palladium(lI)-gold(I11) can be determined simultaneously in the presence of several cations by the proposed method. Q 1988 Academic mess, hc.
INTRODUCTION
The ternary complex of gold(II1) with tetrabutylammonium ion and iodide was used for the gravimetric determination of gold(II1) (I). Serious interferences were reported from bismuth(II1) and mercury(I1). The same complex was used also in the spectrophotometric determination of gold(II1) by extraction into chloroform (2). Serious interferences were reported from Pd(I1) and Pt(IV). Another method for the gravimetric determination of gold(II1) used the ternary complex of gold(II1) with trimethylphenylammonium ion and iodide (3). Serious interferences were reported from Bi(III), Cd(II), Hg(II), Pb(II), Pd(II), Pt(IV), and Tl(1). The extraction of several metal ions with benzyltriethylammonium ion and iodide into MIBK in the presence of EDTA was studied and it was found that only palladium(II), platinum(II), and gold(II1) gave stable colored complexes. In this paper a method for the simultaneous determination of palladium(II)platinum(B) and palladium(II)-gold(II1) & the presence of several cations is reported. EAPERIMENTAL Apparurus and reagcng. A Zeiss Model PMQ3 spectrophotometer with l-cm quartz cells for spectral studies and an Orion Research Model 701A digital pH meter for pH measurements were used. All reagents and solvents were of analytical grade. Procedure for the determination of palladium(ZZ), platinum(ZZ), or gold(ZZZl.
TO
a lOO-ml separating funnel add the test solution containing up to 100 pg of palladium(II), 120 pg of gold(III), or 300 pg of platinum(II), 1 ml of a 1 M EDTA solution, 1 ml of a 1 M benzyltriethylammonium ion solution, 1 ml of a 1 M iodide 18 0026-265X/88 $1.50 Copyright All rights
0 1988 by Academic Press, Inc. of reproduction in any form reserved.
SIMULTANEOUS Simultaneous Determination
19
SPECTROPHOTOMETRY
TABLE 1 of Pd(II)-Pt(II) Ions in the Presence of Several Cations
Absorbance Pd(II)-Pt(II)
Concentration (wm)
1 2 3 4 5
0.174-0.214 0.182-0.210 0.182-0.220 0.176-0.229 0.180-0.226
3.93-3.91 4.11-3.84 4.11-4.02 3.98-4.18 4.07-4.13
Average
0.179-0.220
4.04-4.02
0.07-0.11
Absolute error (ppm)
Relative error m
Relative average deviation (%)
Relative standard deviation (%)
1.73-2.74
1.80-3.19
Determinations
0.04-0.02
l-0.50
Deviation kw-4 -0.11 0.07 0.07 -0.06 0.03
+ + + + f
-0.11 -0.18 0.00 0.16 0.11
solution, buffer solution (CHsCOOH-NH40H, pH 5.0), and 20 ml of MIBK. Shake well for 3 min and measure the absorbance of the organic phase at 360 nm for palladium(H) and at 370 nm for gold(II1) and platinum(I1) against a reference blank containing all the reactants except the metal ions. Procedure for the simultaneous determination of palladium(U)-platinum(ZI) or palladium(ZZ)-gold(ZZZ). Follow the above procedure up to the extraction into
MIBK. Measure the absorbance of the organic phase at 550 nm for palladium(I1) and at 370 nm for platinum(I1) or gold(II1). The absorbance of the platinum(I1) and gold(III) complexes at 370 nm is calculated by subtracting the absorbance of the palladium complex at this wavelength. Application of the method. Two standard solutions were prepared containing 1 x 10V3M Bi(III), Fe(III), Cu(II), Co(II), Ni(II), Cr(III), Mn(II), Hg(II), Ag(I), Pb(II), Cd(H), Zn(II), and Al(II1). The first standard solution contained Pd(II)Pt(I1) and the second Pd(II)-Au(U) at concentrations of 4 ppm. The proposed method was applied and the results are presented in Tables 1 and 2. Simultaneous Determination
TABLE of Pd(II)-Au(III)
2 Ions in the Presence of Several Cations
Absorbance Pd(II)-Au(II1)
Concentration (ppm)
1 2 3 4 5
0.176-0.570 0.178-0.608 0.175-0.619 0.182-0.580 0.177-0.590
3.98-3.87 4.02-4.13 3.95-4.20 4.11-3.94 4.00-4.01
Average
0.178-0.593
4.01-4.03
0.04-0.11
Absolute error (wm)
Relative error (%I
Relative average deviation (%)
Relative standard deviation (%)
0.01-0.03
0.25-0.75
1.00-2.73
1.35-3.00
Determinations
Deviation (r-v) -0.03 0.01 -0.06 0.10 -0.01
+ f + f f
-0.16 0.10 0.17 -0.09 -0.02
20
E . KAVLENTIS
"X. 'pi-.
FIG. 1. Absorption spectra of (a) Pd(II), (b) Au(III), and (c) Pt(II) complexes after 1:l extraction into MIBK. W(H), 1.128 x 10m4M; Au(III), 4.828 x 10e4 M; Pt(II), 1.028 x lo-'M; benzyltriethylammonium ion, 0.1 M; iodide, 0.1 M; EDTA, 0.1 M; pH 5.0.
RESULTS AND DISCUSSION
The extraction of several cations into MIBK with benzyltriethylammonium ion and iodide in the presence of EDTA was examined. The cations tested were Bi(III), Fe(II), Fe(III), Cu(II), Co(II), Ni(II), Cr(III), UO,(II), Mn(II), Pt(II), Pd(II), Au(III), Hg(II), Ag(I), Pb(II), Cd(II), Zn(II), As(III), Sb(III), Sn(II), Al(III), Ti(III), Mo(VI), V(V), W(VI), Ce(III), Tl(I), ZrO(II), Se(VI), Te(VI), La(III), Y(III), and Th(IV). Palladium(II), platinum(B), and gold(III) gave red-, yellow-, and yellow-colored complexes, respectively, into MIBK while color reaction was not observed from the remaining tested cations. Thus the method becomes specific for the determination of the above metal ions. The complexes are stable in slightly acid medium for 2 h at least and the pH value of 5.0 was selected for spectral studies. The absorption spectra of the palladium(H), platinum(B), and gold(II1) complexes in MIBK are presented in Fig. 1. The palladium(I1) complex exhibits two peaks at 360 nm, E 18.6 x lo3 liters x mol-’ X cm-l and at 550 nm, E 4.7 x 103 liters X mol-l x cm-‘. The platinum(I1) and gold(II1) complexes exhibit one peak at 370 nm with E values 10.7 x lo3 liters x mol-i x cm-’ and 29.0 x lo3 liters x mol-l x cm-l, respectively. The formula LAuI, was proposed for the corresponding complex of gold(III) with tetrabutylammonium ion and iodide (1). The formulas L,PdI,, L2Pt14, and LAuI, are proposed for the complexes of palladium(II), platinum(II), and gold(II1) with benzyltriethylammonium ion and iodide. Palladium(I1) can be determined in the range 0.15-5 ppm at 360 nm or 0.6-18
SIMULTANEOUS
SPECTROPHOTOMETRY
21
ppm at 550 nm, platinum(H) in the range OS- 15 ppm at 370 nm, and gold(II1) in the range 0.2-6 ppm at 370 nm. The remaining tested cations do not interfere but if their concentration is high the reagents must be used at excess. The interferences from several anions were examined. Sulfide, cyanide, and thiocyanate seriously interfered at ~0. l-fold. F-, Cl-, Br-, oxalate tartrate, and citrate did not interfere. REFERENCES 1. Hemandez-Mendez, J.; Alonso-Mateos, A.; Martin-Mateos, E. J.; Garcia De Maria, C. Rev. Roum. Chim., 1982, 27, 981-986. 2. Hemandez-Mendez, J.; Alonso-Mateos, A.; Martin-Mateos, E. J.; Garcia De Maria, C. Anal. Lat., 1982, 15, 883-889. 3. White, W. W.; Zuber, J. R. Anal. Chem., 1964, 36, 2363-2364.
JOURNAL
37, 18-21 (1988)
Simultaneous Extractive Palladium(ll)-Platinum(ll) Benzyltriethylammonium
Spectrophotometric Determination or Palladium(ll)-Gold(lll) with Ion and Iodide in the Presence of EDTA
of
E . KAVLENTIS Department of Chemistry, University of Thessaloniki, Thessaloniki, Greece Received February 7, 1987; accepted September 14, 1987 Palladium(II), platinum(H), and gold(II1) react with benzyltriethylammonium ion and iodide in slightly acid medium to form water-insoluble colored ternary complexes stable in the presence of EDTA and extractable into MIBK. Palladium(II)-platinum(I1) and palladium(lI)-gold(I11) can be determined simultaneously in the presence of several cations by the proposed method. Q 1988 Academic mess, hc.
INTRODUCTION
The ternary complex of gold(II1) with tetrabutylammonium ion and iodide was used for the gravimetric determination of gold(II1) (I). Serious interferences were reported from bismuth(II1) and mercury(I1). The same complex was used also in the spectrophotometric determination of gold(II1) by extraction into chloroform (2). Serious interferences were reported from Pd(I1) and Pt(IV). Another method for the gravimetric determination of gold(II1) used the ternary complex of gold(II1) with trimethylphenylammonium ion and iodide (3). Serious interferences were reported from Bi(III), Cd(II), Hg(II), Pb(II), Pd(II), Pt(IV), and Tl(1). The extraction of several metal ions with benzyltriethylammonium ion and iodide into MIBK in the presence of EDTA was studied and it was found that only palladium(II), platinum(II), and gold(II1) gave stable colored complexes. In this paper a method for the simultaneous determination of palladium(II)platinum(B) and palladium(II)-gold(II1) & the presence of several cations is reported. EAPERIMENTAL Apparurus and reagcng. A Zeiss Model PMQ3 spectrophotometer with l-cm quartz cells for spectral studies and an Orion Research Model 701A digital pH meter for pH measurements were used. All reagents and solvents were of analytical grade. Procedure for the determination of palladium(ZZ), platinum(ZZ), or gold(ZZZl.
TO
a lOO-ml separating funnel add the test solution containing up to 100 pg of palladium(II), 120 pg of gold(III), or 300 pg of platinum(II), 1 ml of a 1 M EDTA solution, 1 ml of a 1 M benzyltriethylammonium ion solution, 1 ml of a 1 M iodide 18 0026-265X/88 $1.50 Copyright All rights
0 1988 by Academic Press, Inc. of reproduction in any form reserved.
SIMULTANEOUS Simultaneous Determination
19
SPECTROPHOTOMETRY
TABLE 1 of Pd(II)-Pt(II) Ions in the Presence of Several Cations
Absorbance Pd(II)-Pt(II)
Concentration (wm)
1 2 3 4 5
0.174-0.214 0.182-0.210 0.182-0.220 0.176-0.229 0.180-0.226
3.93-3.91 4.11-3.84 4.11-4.02 3.98-4.18 4.07-4.13
Average
0.179-0.220
4.04-4.02
0.07-0.11
Absolute error (ppm)
Relative error m
Relative average deviation (%)
Relative standard deviation (%)
1.73-2.74
1.80-3.19
Determinations
0.04-0.02
l-0.50
Deviation kw-4 -0.11 0.07 0.07 -0.06 0.03
+ + + + f
-0.11 -0.18 0.00 0.16 0.11
solution, buffer solution (CHsCOOH-NH40H, pH 5.0), and 20 ml of MIBK. Shake well for 3 min and measure the absorbance of the organic phase at 360 nm for palladium(H) and at 370 nm for gold(II1) and platinum(I1) against a reference blank containing all the reactants except the metal ions. Procedure for the simultaneous determination of palladium(U)-platinum(ZI) or palladium(ZZ)-gold(ZZZ). Follow the above procedure up to the extraction into
MIBK. Measure the absorbance of the organic phase at 550 nm for palladium(I1) and at 370 nm for platinum(I1) or gold(II1). The absorbance of the platinum(I1) and gold(III) complexes at 370 nm is calculated by subtracting the absorbance of the palladium complex at this wavelength. Application of the method. Two standard solutions were prepared containing 1 x 10V3M Bi(III), Fe(III), Cu(II), Co(II), Ni(II), Cr(III), Mn(II), Hg(II), Ag(I), Pb(II), Cd(H), Zn(II), and Al(II1). The first standard solution contained Pd(II)Pt(I1) and the second Pd(II)-Au(U) at concentrations of 4 ppm. The proposed method was applied and the results are presented in Tables 1 and 2. Simultaneous Determination
TABLE of Pd(II)-Au(III)
2 Ions in the Presence of Several Cations
Absorbance Pd(II)-Au(II1)
Concentration (ppm)
1 2 3 4 5
0.176-0.570 0.178-0.608 0.175-0.619 0.182-0.580 0.177-0.590
3.98-3.87 4.02-4.13 3.95-4.20 4.11-3.94 4.00-4.01
Average
0.178-0.593
4.01-4.03
0.04-0.11
Absolute error (wm)
Relative error (%I
Relative average deviation (%)
Relative standard deviation (%)
0.01-0.03
0.25-0.75
1.00-2.73
1.35-3.00
Determinations
Deviation (r-v) -0.03 0.01 -0.06 0.10 -0.01
+ f + f f
-0.16 0.10 0.17 -0.09 -0.02
20
E . KAVLENTIS
"X. 'pi-.
FIG. 1. Absorption spectra of (a) Pd(II), (b) Au(III), and (c) Pt(II) complexes after 1:l extraction into MIBK. W(H), 1.128 x 10m4M; Au(III), 4.828 x 10e4 M; Pt(II), 1.028 x lo-'M; benzyltriethylammonium ion, 0.1 M; iodide, 0.1 M; EDTA, 0.1 M; pH 5.0.
RESULTS AND DISCUSSION
The extraction of several cations into MIBK with benzyltriethylammonium ion and iodide in the presence of EDTA was examined. The cations tested were Bi(III), Fe(II), Fe(III), Cu(II), Co(II), Ni(II), Cr(III), UO,(II), Mn(II), Pt(II), Pd(II), Au(III), Hg(II), Ag(I), Pb(II), Cd(II), Zn(II), As(III), Sb(III), Sn(II), Al(III), Ti(III), Mo(VI), V(V), W(VI), Ce(III), Tl(I), ZrO(II), Se(VI), Te(VI), La(III), Y(III), and Th(IV). Palladium(II), platinum(B), and gold(III) gave red-, yellow-, and yellow-colored complexes, respectively, into MIBK while color reaction was not observed from the remaining tested cations. Thus the method becomes specific for the determination of the above metal ions. The complexes are stable in slightly acid medium for 2 h at least and the pH value of 5.0 was selected for spectral studies. The absorption spectra of the palladium(H), platinum(B), and gold(II1) complexes in MIBK are presented in Fig. 1. The palladium(I1) complex exhibits two peaks at 360 nm, E 18.6 x lo3 liters x mol-’ X cm-l and at 550 nm, E 4.7 x 103 liters X mol-l x cm-‘. The platinum(I1) and gold(II1) complexes exhibit one peak at 370 nm with E values 10.7 x lo3 liters x mol-i x cm-’ and 29.0 x lo3 liters x mol-l x cm-l, respectively. The formula LAuI, was proposed for the corresponding complex of gold(III) with tetrabutylammonium ion and iodide (1). The formulas L,PdI,, L2Pt14, and LAuI, are proposed for the complexes of palladium(II), platinum(II), and gold(II1) with benzyltriethylammonium ion and iodide. Palladium(I1) can be determined in the range 0.15-5 ppm at 360 nm or 0.6-18
SIMULTANEOUS
SPECTROPHOTOMETRY
21
ppm at 550 nm, platinum(H) in the range OS- 15 ppm at 370 nm, and gold(II1) in the range 0.2-6 ppm at 370 nm. The remaining tested cations do not interfere but if their concentration is high the reagents must be used at excess. The interferences from several anions were examined. Sulfide, cyanide, and thiocyanate seriously interfered at ~0. l-fold. F-, Cl-, Br-, oxalate tartrate, and citrate did not interfere. REFERENCES 1. Hemandez-Mendez, J.; Alonso-Mateos, A.; Martin-Mateos, E. J.; Garcia De Maria, C. Rev. Roum. Chim., 1982, 27, 981-986. 2. Hemandez-Mendez, J.; Alonso-Mateos, A.; Martin-Mateos, E. J.; Garcia De Maria, C. Anal. Lat., 1982, 15, 883-889. 3. White, W. W.; Zuber, J. R. Anal. Chem., 1964, 36, 2363-2364.