- Email: [email protected]
Spectrophotometric determination of thallium(lll) with thiosalicyl-amide
SHORT
I55
COAlMUNICATIONS
Spectrophotometric amide
determination
of
thaliium(lll)
with
thiosalicyl-
Very few organic reagents 11ave been successfully employed for the extraction and spectrophotometric determination of thallium(III). Thallium has been extracted with diethyldithiocarbamate in chloroform1 and with dithizone in chloroform2; in both cases, tartrate and cyanide are needed to mask interfering ions. Extraction with zinc dibenzyldithiocarbamate has also been used”. Recently, SEOME ct (~1.4suggested 3-hydroxy-1,3-diphenyltriazine for the spectrophotometric determination of the metal in 70% alcohol. Thiosalicylamide has been employed by KRYCII AND LIPIECG for the colorimetric determination of traces of iron. In the present research the analytical properties of thiosalicylamide have been investigated in detail and the reagent has been studied for the spectrophotometric determination of tl~allium(III). Thiosalicylamide forms an orange-red complcs wit11 thallium(III), which can be easily extracted with chloroform to produce an orange-red colour. Quantitative extraction is obtained from z-3.5 N sulphuric acid solutions. Tlic cllloroform estract of the thallium-thiosalicylamide complex shows nlaximum absorbance at 458 nm, and 13eer’s law is obeyed over the range z.8-56 /~g Tl3+/ml. Apprcciablc amounts of aluminium, gallium, indium, thorium, iron, copper, manganese, titanium, zinc, cobalt and nickel do not interfere. The reagent forms coloured complexes with several otllcr metals such as copper, iron, gold, platinum, palladium, ruthenium , osmium, rhodium and vanadium. Tile determination and separation of thcsc metals inclucliilg the elements of the platinum group are in progress. A@aratzls A Carl-Zeiss spcctropllotometer PMQII type with ~-cm for the transmittance measurements. All the pEr measurements a Cambridge PH meter (Bench model).
quartz cells was used wcrc carried out with
Ranged
and chemicals Preparation a,& $wojxvties of t/lioscrlicylazllirle. Thiosalicylamide (TSA) was prepared by the following procedure”. Salicylamicle was mixed with l~liosl~l~orus pentasulphide and baked over a low flame in a porcelain basin. The mixture was dissolved in rectified spirit and filtered. The filtrate was added to a large volume of boiling water, ‘and filtered again, and the filtrate was slowly evaporated on a water bath. Shining yellow needles separated on cooling. The compound was recrystallised from hot water (m.p. x2x0). The compound is appreciably soluble in hot water ancl very soluble in alcohol, benzene, chloroform and other organic solvents. It is stable towards acid and readily decomposed by alkali. Thallium solution. A known quantity of thallium(II1) oxide was dissolved in nitric acid and then made to volume with water. The solution was standardised by the iodimetric method. Weaker solutions were prepared by dilution with water. Other standard solutions of different metals used to study the effect of diverse ions were prepared by dissolving weighed amounts of their salts in distilled water or A,r~nl.Claim. Acfn,
46
(rgGg) 155-158
156
SHORT
dilute sulphuric acid. Solutions of anions were prepared salts. All the chemicals used were of AR. grade.
from
COMMUNICATIONS
the respective
alkali
I’lace a measured amount of thallium solution into a xoo-ml separating funnel, ancl make the solution 2.0-3.5 N in sulphuric acid. Shake vigorously with a measured amount of alcoholic 0.01 M thiosalicylamide solution. Then shake the orange-red precipitate with three or four s-ml portions of chloroform. Dilute the combined extracts to 25 ml with chloroform, and measure the absorbance at 460 nm against a reagent bl an Ii. A bsorbauce
CZ~YVCS
The absorbance curves of solutions of thallium-TSA &elate in chloroform obtained after extraction from 2.5 iV sulphuric acid media are shown in Fig. I.
I’5 1’4 I’3 Ii? I’I I’0 ‘9
‘8 ‘? ‘6 ‘5
‘4 5
420
440
460
Weve
Fig.
(A)
I. Absorbance [Tl”+]=28.03
length
480
500
520
540
-
curves of thallium(III)-TSA pg/ml; (p) [TP+]=22.424
complex in chloroform. ( l3) [TP+l= fig/ml;
(0)
[T13+] =16.818,ug/ml;
(0)
44.85 p&ml;
[R]=I-IO-8M.
Ejyxt of pN The most suitable acidity for complete extraction of thallium was determined by extracting the chelate after adjustment of the PH with varying amounts of 10% And.
Cl&n.
Acfn,
46 (IgGg)
155-158
SHORT
157
COXsfMUNICATIONS
sodium acetate and dilute sulphuric acid. The transmittance of the different estracts was measured at 460 nm against the appropriate reagent blank. The acidity of the aqueous layers was measured immediately after extraction of _thallium. The results indicated that the extraction of thallium starts at p)t 3.25, becomes 50% at PH 1.0 and IOO~/~ in the range of acidity 1.5-3.5 N. At higher acidities the percentage extraction gradually diminishes and at 6 N sulphuric acid the reagent decomposes. Effect of diverse ions In the study of the effect of diverse ions, the standard thallium(III) solution containing 280.3 ,ug of the metal ion was mixed with a solution of the required ion, the acidity was adjusted to 2.0-2.5 N with sulphuric acid, 0.6 ml of 0.01 M reagent was added, and the mixture was extracted four times with 5-ml portions of chloroform. The combined extract was then collected in a 25-ml volumetric flask and made to volume with the solvent, and the absorbance was measured at 460 nm against the reagent blank. Table I shows the concentrations of the foreign ions that caused an error of less than + 2 cyo. TAXSLIS EPPECY
I OF
131VISKSE
1ONS
(Thnlliu~n talccn= 208.3 jig) D ivcrse added
Diverse rcdded
ions
Ti
4 b
‘ZOO
v
0 .+.
500 800 750 500 50
Mo”+
Nj’-‘.
200
co2+ Mna+ %n2+ Cd".+ Cl-W Ga3+ In=+ A13+
GO
80
iom
Comrnlrulion tslcratcd (“Wl
-_.-.
U0.b
108 05 20 70
I-I 1’042-
FE 1x-A 'Ewtmtc
The empirical formula of the thallium-TSA complex was determined by the mole-ratio method as described by MAYER AND Awm7. A series of solutions were taken which contained 4. IO-~ M tl~allium(III) and various concentrations of thiosalicylamide in the range 3.2 - IO-G- 20 - IO-G M. The metal complex was extracted with chloroform as described before and the absorbance measured was plotted against the mole ratio of ligancl to metal ion. The results clearly showed a stable complex containing thallium and TSA in the ratio I :z. This ratio was verified by the conventional slope-ratio method. Molar extinction coefficient and sensitivity The molar extinction coefficient was found to be 5x00-+ IO. The sensitivity for the thallium-TSA complex was found to be 0.04 rug/cm2 according to Sandell’s notatione. Apzal.
China.
Acla,
46 (rgbg)
155-158
SHORT COMMUNICATIONS
W3
The authors arc indebted to the Council of Scientific and Industrial Research, New Delhi, for a fellowship awarded to M.M. They thank Dr. H. 12. DAS for helpful discussion. S. C. SHOME M. MAZUMDAIZ
Chemistry Ihj5artnzcnt, Presidegzcy Collqqe, Calcutta-r2 (India)
7 A. s. 8
@.
U.
hfAYl
Intcrscicncc,
P. 83. (Rcceivcd
New
Yorlc,
1959.
December 30 th , IC)M)
Analytical applications of thio-, Part I. Detection of palladium
seleno-
and telluroethers
LIVINGSTONEI has reviewed the different types of metal complexes formed by various ligands containing sulfur, selenium or tellurium as donor atoms. Among these, the properties of thioethers, selcnoethcrs and telluroethers toward certain metals seemed particularly attractive. It is well known that palladium chloride readily forms very well defined compounds with thioethers : PdCla - zR-,S. These complexes are soluble in chloroform, benzene, ligroin, etc., and have been used to characterize alkyl-phenyl sulfidesl-3. On the basis of these facts a new test for the identification of palladium was developed. This study, however, was carried out mainly to demonstrate the possibility of using a whole class of very simple organic substances to detect palladium rather than to select a single reagent for this purpose. Thio-, seleno- and telluroethers in benzene solutions were used to extract palladium chloride. Extraction study Series of experiments were run with aqueous solutions of palladium chloride with the PH adjusted between 1.0 and 5.0; 3% solutions of the organic reagent in benzene were used as extractant (Table I). The extraction was evaluated by the intensity of the yellow color of the extract. Atrtrl. Chirn. Acta, 40 (x969) x58-101
I55
COAlMUNICATIONS
Spectrophotometric amide
determination
of
thaliium(lll)
with
thiosalicyl-
Very few organic reagents 11ave been successfully employed for the extraction and spectrophotometric determination of thallium(III). Thallium has been extracted with diethyldithiocarbamate in chloroform1 and with dithizone in chloroform2; in both cases, tartrate and cyanide are needed to mask interfering ions. Extraction with zinc dibenzyldithiocarbamate has also been used”. Recently, SEOME ct (~1.4suggested 3-hydroxy-1,3-diphenyltriazine for the spectrophotometric determination of the metal in 70% alcohol. Thiosalicylamide has been employed by KRYCII AND LIPIECG for the colorimetric determination of traces of iron. In the present research the analytical properties of thiosalicylamide have been investigated in detail and the reagent has been studied for the spectrophotometric determination of tl~allium(III). Thiosalicylamide forms an orange-red complcs wit11 thallium(III), which can be easily extracted with chloroform to produce an orange-red colour. Quantitative extraction is obtained from z-3.5 N sulphuric acid solutions. Tlic cllloroform estract of the thallium-thiosalicylamide complex shows nlaximum absorbance at 458 nm, and 13eer’s law is obeyed over the range z.8-56 /~g Tl3+/ml. Apprcciablc amounts of aluminium, gallium, indium, thorium, iron, copper, manganese, titanium, zinc, cobalt and nickel do not interfere. The reagent forms coloured complexes with several otllcr metals such as copper, iron, gold, platinum, palladium, ruthenium , osmium, rhodium and vanadium. Tile determination and separation of thcsc metals inclucliilg the elements of the platinum group are in progress. A@aratzls A Carl-Zeiss spcctropllotometer PMQII type with ~-cm for the transmittance measurements. All the pEr measurements a Cambridge PH meter (Bench model).
quartz cells was used wcrc carried out with
Ranged
and chemicals Preparation a,& $wojxvties of t/lioscrlicylazllirle. Thiosalicylamide (TSA) was prepared by the following procedure”. Salicylamicle was mixed with l~liosl~l~orus pentasulphide and baked over a low flame in a porcelain basin. The mixture was dissolved in rectified spirit and filtered. The filtrate was added to a large volume of boiling water, ‘and filtered again, and the filtrate was slowly evaporated on a water bath. Shining yellow needles separated on cooling. The compound was recrystallised from hot water (m.p. x2x0). The compound is appreciably soluble in hot water ancl very soluble in alcohol, benzene, chloroform and other organic solvents. It is stable towards acid and readily decomposed by alkali. Thallium solution. A known quantity of thallium(II1) oxide was dissolved in nitric acid and then made to volume with water. The solution was standardised by the iodimetric method. Weaker solutions were prepared by dilution with water. Other standard solutions of different metals used to study the effect of diverse ions were prepared by dissolving weighed amounts of their salts in distilled water or A,r~nl.Claim. Acfn,
46
(rgGg) 155-158
156
SHORT
dilute sulphuric acid. Solutions of anions were prepared salts. All the chemicals used were of AR. grade.
from
COMMUNICATIONS
the respective
alkali
I’lace a measured amount of thallium solution into a xoo-ml separating funnel, ancl make the solution 2.0-3.5 N in sulphuric acid. Shake vigorously with a measured amount of alcoholic 0.01 M thiosalicylamide solution. Then shake the orange-red precipitate with three or four s-ml portions of chloroform. Dilute the combined extracts to 25 ml with chloroform, and measure the absorbance at 460 nm against a reagent bl an Ii. A bsorbauce
CZ~YVCS
The absorbance curves of solutions of thallium-TSA &elate in chloroform obtained after extraction from 2.5 iV sulphuric acid media are shown in Fig. I.
I’5 1’4 I’3 Ii? I’I I’0 ‘9
‘8 ‘? ‘6 ‘5
‘4 5
420
440
460
Weve
Fig.
(A)
I. Absorbance [Tl”+]=28.03
length
480
500
520
540
-
curves of thallium(III)-TSA pg/ml; (p) [TP+]=22.424
complex in chloroform. ( l3) [TP+l= fig/ml;
(0)
[T13+] =16.818,ug/ml;
(0)
44.85 p&ml;
[R]=I-IO-8M.
Ejyxt of pN The most suitable acidity for complete extraction of thallium was determined by extracting the chelate after adjustment of the PH with varying amounts of 10% And.
Cl&n.
Acfn,
46 (IgGg)
155-158
SHORT
157
COXsfMUNICATIONS
sodium acetate and dilute sulphuric acid. The transmittance of the different estracts was measured at 460 nm against the appropriate reagent blank. The acidity of the aqueous layers was measured immediately after extraction of _thallium. The results indicated that the extraction of thallium starts at p)t 3.25, becomes 50% at PH 1.0 and IOO~/~ in the range of acidity 1.5-3.5 N. At higher acidities the percentage extraction gradually diminishes and at 6 N sulphuric acid the reagent decomposes. Effect of diverse ions In the study of the effect of diverse ions, the standard thallium(III) solution containing 280.3 ,ug of the metal ion was mixed with a solution of the required ion, the acidity was adjusted to 2.0-2.5 N with sulphuric acid, 0.6 ml of 0.01 M reagent was added, and the mixture was extracted four times with 5-ml portions of chloroform. The combined extract was then collected in a 25-ml volumetric flask and made to volume with the solvent, and the absorbance was measured at 460 nm against the reagent blank. Table I shows the concentrations of the foreign ions that caused an error of less than + 2 cyo. TAXSLIS EPPECY
I OF
131VISKSE
1ONS
(Thnlliu~n talccn= 208.3 jig) D ivcrse added
Diverse rcdded
ions
Ti
4 b
‘ZOO
v
0 .+.
500 800 750 500 50
Mo”+
Nj’-‘.
200
co2+ Mna+ %n2+ Cd".+ Cl-W Ga3+ In=+ A13+
GO
80
iom
Comrnlrulion tslcratcd (“Wl
-_.-.
U0.b
108 05 20 70
I-I 1’042-
FE 1x-A 'Ewtmtc
The empirical formula of the thallium-TSA complex was determined by the mole-ratio method as described by MAYER AND Awm7. A series of solutions were taken which contained 4. IO-~ M tl~allium(III) and various concentrations of thiosalicylamide in the range 3.2 - IO-G- 20 - IO-G M. The metal complex was extracted with chloroform as described before and the absorbance measured was plotted against the mole ratio of ligancl to metal ion. The results clearly showed a stable complex containing thallium and TSA in the ratio I :z. This ratio was verified by the conventional slope-ratio method. Molar extinction coefficient and sensitivity The molar extinction coefficient was found to be 5x00-+ IO. The sensitivity for the thallium-TSA complex was found to be 0.04 rug/cm2 according to Sandell’s notatione. Apzal.
China.
Acla,
46 (rgbg)
155-158
SHORT COMMUNICATIONS
W3
The authors arc indebted to the Council of Scientific and Industrial Research, New Delhi, for a fellowship awarded to M.M. They thank Dr. H. 12. DAS for helpful discussion. S. C. SHOME M. MAZUMDAIZ
Chemistry Ihj5artnzcnt, Presidegzcy Collqqe, Calcutta-r2 (India)
7 A. s. 8
@.
U.
hfAYl
Intcrscicncc,
P. 83. (Rcceivcd
New
Yorlc,
1959.
December 30 th , IC)M)
Analytical applications of thio-, Part I. Detection of palladium
seleno-
and telluroethers
LIVINGSTONEI has reviewed the different types of metal complexes formed by various ligands containing sulfur, selenium or tellurium as donor atoms. Among these, the properties of thioethers, selcnoethcrs and telluroethers toward certain metals seemed particularly attractive. It is well known that palladium chloride readily forms very well defined compounds with thioethers : PdCla - zR-,S. These complexes are soluble in chloroform, benzene, ligroin, etc., and have been used to characterize alkyl-phenyl sulfidesl-3. On the basis of these facts a new test for the identification of palladium was developed. This study, however, was carried out mainly to demonstrate the possibility of using a whole class of very simple organic substances to detect palladium rather than to select a single reagent for this purpose. Thio-, seleno- and telluroethers in benzene solutions were used to extract palladium chloride. Extraction study Series of experiments were run with aqueous solutions of palladium chloride with the PH adjusted between 1.0 and 5.0; 3% solutions of the organic reagent in benzene were used as extractant (Table I). The extraction was evaluated by the intensity of the yellow color of the extract. Atrtrl. Chirn. Acta, 40 (x969) x58-101