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αPicolinic acid as a colorimetric reagent
ANALYTICA.
384
a-PICOLINIC ACID AS III: DETERMINATION
ANIL
KUMAR
VOL. 8 (1953)
CHIMICA ACTA
A COLORIMETRIC OF IRON AND
MAJUMDAR
AND
REAGENT ALUMINIWM
BUDDHADEV
Xttovganic Chenaisivy LabovaLovics, Collcgc of En&at+ering (Ind1r1)
SEN
& l’rclrnolog)~, Ca&ul&i-32,
I fi previous communications *, Part I and II of this series, it was shown that a-picolinic acid could be used as a rcagcnt for the calorimetric determination of iron from 0.08 p.p.m to 12 p.p.m in a cell of thickness 20 mm and capacity 16 ml and the optimum range with minimum relative error was in the region of 1.6 p.p.m. to 8 p.p.m. The experimental results were not influenced by the time, temperature, per in the alkaline range, excess of reagent, cyanide and rcducing agents, and the presence of numerous ions including aluminium (with excess of a-picolinic acid and alkali cyanide). Other well known and most widely used methods for iron include thiocyanate*, 2,2’-bipyridy14 and x,ro-phenanthrolineG. Some of the recent thioglycollatea, methods for the colorimctric determination of aluminium proposed from time to time are due to aluminonO, alizarin’, hematoxyli+, criochromecyanine RD and with chloroform). 8-oxine-chloroform extraction pro8-oxinci” (w h en extracted cedure is applicable over a pi of 4.5 to x1.5, except between 6.5 and 8 and then iron both in the bivalent and trivalent states interfered in acid and alkaline mediall. There the iron interference was removed by converting it to ferrocyanide. In Part II was reported some other methods for the removal of iron before the determination of aluminium. Recently SPRAIN AND BANKS~* utilised the reagent ~,ro-phenanthrolinc as a complexing agent for iron to determine the iron spectrophotometrically and at the same time to remove its interfering effect from aluminium which was then extracted with a chloroform solution of 8-oxine. In cost l3 of the complcxing view of the prohibitive agent, in this present investigation the reagent a-picolinic acid is used to complex iron in the presence of an eScess of cyanide to keep the aluminium in solution and to measure the colour intensity due to iron. The aluminium is then determined from the same solution or from an aliquot of it by extracting the oxine complex with chloroform and measuring the absorbancy of the yellow colour of the tris (8-oxine) aluminium (III) in the chloroform solution. ll’cof&rcnccsJo. 387.
VOL. 8
(wxi)
a-PICOLINIC ACID AS COLORIMETRIC REAGENT III
385
EXPERIMENTAL AI1 transmittancy eIectric calorimeter,
measurements were made with a Klett-Summerson using a cell of 12 mm diam. and 15 ml capacity.
photo-
Reagents
Only reagent quality chemicals, as far as possible, were used. a-picolinic acid solution : A IO/~ solution was prepared from re-crystallised a-picolinic acid of m.p. 130-132~ C in 100 ml distilled water. 8-oxine solution: The chloroform though of reagent quality (blerck) was purified in the way suggested by GRNTRY AND SIIERHINGTON~~ and then washed with water and distilled and a IOA, solution of 8-hydroxyquinolinc in chloroform was prepared. Other solutions used were a 5OA, solution of hydroxylaminc hydrochloride in distilled water, a IO”/~ solution of potassium cyanide in distilled water and a o.orN acetic acid solution. Standard solutions: Standard solutions in distilled water for aluminium and iron (III) were obtained from the respective sulphatc and nitrate. pIr papers of British Drug Houses Ltd., were used to adjust the prr of the solutions. RECOMMENDED PROCEDURE To a solution containing different quantities of aluminium and iron wcrc added I ml of the hydroxylamine hydrochloride solution to reduce the iron and then I ml each of the reagent a-picolinic acid and the cyanide with stirring in the order stated, and the volume of the solution was made up to 50 ml in a volumetric flask. Absorption measurements at 440 m/c (Filter 44) were carried out on a portion of the orange yellow coloured solution so prepared (cf. Part 1 of the series). After the iron determination, a measured aliquot from the volumetric flask was taken in a separating funnel and treated with the acetic acid solution to adjust the pIr of the aliquot to 4. I ml of the 8-oxine solution in chloroform was added to the solution followed by 5 ml portion of distilled chloroform. The contents were shaken for a few minutes, the excess pressure being released by rcmoving the stopper. The two layers are allowed to separate and the chloroform layer is run in a stoppered flask containing a few grams (2 g) of fused calcium chloride. The extraction with the chloroform solution is repented till the chloroform layer is cdlourless. After drying, the chloroform solution was made up to 50 ml with some extra chloroform and the optical density of the yellow coloured aluminiumoxine complex solution was measured at 400 rnp (Filter 40), using blank solution as the reference solution. Results arc given in Table I. Rcfercnccs
p. 387.
A.
386
K.
MAJUMDAR,
B.
SEN
VOL.
8
(1953)
To calculate the results, the “calibration factor” was determined by meascring the transmittancy of a number of known solutions of iron and aluminium treated in the same way as described above. The scale readings of the unknown solutions were multiplied by the “calibration factor” for the concentrations of the known. TABLE .
- -_-_. Iron prcscnt. cc& ----_. ._.
..--..-. - - -..- ----Aluminium present. pg .______ _. _ __-. __. _ ___.._
100
IO0
100
200
IO0
4oo
100
I ..-.I-_-. Iron -.
- . .--.found. Aluminium c(g c(g .-_. ___._.--__-_---_ IO0 100
20
LOO
50 100
100
IO0
;: 20
100
-.-.
;o"
100
100
.
100 100 100
19 39 50
100 100 GO
40
99
203 396 4oo -
100 100
z: IO0
TOO
- ---_
_...- _ _. found.
.-_.----_---__--___--__--__-
100
40
IO0
20
___.-. -_._ -_
__-._-_.
._
SUMMARY A very simple, rapid and accurate method for the calorimetric estimation of micro amounts of iron and aluminiuxr from the same solution has been described. The iron is determined in the ferrous state by its orange yellow colour with a-picolinic acid in the presence of an alkali c anide, and aluminium concentration is measured from the yellow colour given by trie chloroform solution of the aluminiumoxine complex after masking the effect due to iron by a-picolinic acid. RESUME Une m&hode de dosage colorimetrique trds simple, rapide et recise, est d&rite, ermettant de determiner Fe et Al dans la meme solution. Le Per est dose B I’btat Perreux par l’acide a-picolinique, en presence de cyanure alcalin (coloration ‘aune orange) et l’aluminium par extraction du complexe aluminium-oxine dans le c &loroforme (coloration jaunt) apres mssquage du fer par l’acide a-picolinique. ZUSAMMENFASSUNG Es wurde einc sehr einfache schnelle und enaue Methode zur kolorimetrischen Bestimmung von Mikromengcn Eisen und A Puminium in der gleichen Losung beschrieben. Eisen wird als zweiwertiges Eisen durch die orangegelbe Farbe mit u-Picolinslure in Gcgcnwart von Alkalicyanid bestimmt. Die Aluminiumkonzentration wird durch die gelbe Farbe bestimmt, die eine Chloroformldsung des Aluminiumoxinkomplexes nach dem Maskieren des Eisens mit a-Picolins8ure gibt. I?eferences p. 387.
VOL.
8 (1953)
a-PICOLINIC
ACID
AS
COLORIMETRIC
REAGENT
387
III
1 A. Ii, MAJUMDAR AND 13. SET’, :fmzi. Chrm. Arlrt. 8 (19.53) 3Gt). 378. * J. T. \VOORS AP*'D M. G. M'IL~LI,OS. Imll. Ilvg. C'h~m. .*I lrttl. I:'d, 13 (1941) 551. 8 H. W. SWANK AND R/I. G. MELLOX, fwi. IZ*zg.C'lrcru., :Junl. Jlrl., xo (1938) 7. 4 \V. B. FORTUNE AND IQ. G. MELAOS, itrrt’. E’:?t$. CTItctt~.,Awrl. Ed., IO (1938) 60. * L. G. SAYWELL AND ES. B. CUNNINGHAS%, Imti. l
Received
January
27th,
~953
384
a-PICOLINIC ACID AS III: DETERMINATION
ANIL
KUMAR
VOL. 8 (1953)
CHIMICA ACTA
A COLORIMETRIC OF IRON AND
MAJUMDAR
AND
REAGENT ALUMINIWM
BUDDHADEV
Xttovganic Chenaisivy LabovaLovics, Collcgc of En&at+ering (Ind1r1)
SEN
& l’rclrnolog)~, Ca&ul&i-32,
I fi previous communications *, Part I and II of this series, it was shown that a-picolinic acid could be used as a rcagcnt for the calorimetric determination of iron from 0.08 p.p.m to 12 p.p.m in a cell of thickness 20 mm and capacity 16 ml and the optimum range with minimum relative error was in the region of 1.6 p.p.m. to 8 p.p.m. The experimental results were not influenced by the time, temperature, per in the alkaline range, excess of reagent, cyanide and rcducing agents, and the presence of numerous ions including aluminium (with excess of a-picolinic acid and alkali cyanide). Other well known and most widely used methods for iron include thiocyanate*, 2,2’-bipyridy14 and x,ro-phenanthrolineG. Some of the recent thioglycollatea, methods for the colorimctric determination of aluminium proposed from time to time are due to aluminonO, alizarin’, hematoxyli+, criochromecyanine RD and with chloroform). 8-oxine-chloroform extraction pro8-oxinci” (w h en extracted cedure is applicable over a pi of 4.5 to x1.5, except between 6.5 and 8 and then iron both in the bivalent and trivalent states interfered in acid and alkaline mediall. There the iron interference was removed by converting it to ferrocyanide. In Part II was reported some other methods for the removal of iron before the determination of aluminium. Recently SPRAIN AND BANKS~* utilised the reagent ~,ro-phenanthrolinc as a complexing agent for iron to determine the iron spectrophotometrically and at the same time to remove its interfering effect from aluminium which was then extracted with a chloroform solution of 8-oxine. In cost l3 of the complcxing view of the prohibitive agent, in this present investigation the reagent a-picolinic acid is used to complex iron in the presence of an eScess of cyanide to keep the aluminium in solution and to measure the colour intensity due to iron. The aluminium is then determined from the same solution or from an aliquot of it by extracting the oxine complex with chloroform and measuring the absorbancy of the yellow colour of the tris (8-oxine) aluminium (III) in the chloroform solution. ll’cof&rcnccsJo. 387.
VOL. 8
(wxi)
a-PICOLINIC ACID AS COLORIMETRIC REAGENT III
385
EXPERIMENTAL AI1 transmittancy eIectric calorimeter,
measurements were made with a Klett-Summerson using a cell of 12 mm diam. and 15 ml capacity.
photo-
Reagents
Only reagent quality chemicals, as far as possible, were used. a-picolinic acid solution : A IO/~ solution was prepared from re-crystallised a-picolinic acid of m.p. 130-132~ C in 100 ml distilled water. 8-oxine solution: The chloroform though of reagent quality (blerck) was purified in the way suggested by GRNTRY AND SIIERHINGTON~~ and then washed with water and distilled and a IOA, solution of 8-hydroxyquinolinc in chloroform was prepared. Other solutions used were a 5OA, solution of hydroxylaminc hydrochloride in distilled water, a IO”/~ solution of potassium cyanide in distilled water and a o.orN acetic acid solution. Standard solutions: Standard solutions in distilled water for aluminium and iron (III) were obtained from the respective sulphatc and nitrate. pIr papers of British Drug Houses Ltd., were used to adjust the prr of the solutions. RECOMMENDED PROCEDURE To a solution containing different quantities of aluminium and iron wcrc added I ml of the hydroxylamine hydrochloride solution to reduce the iron and then I ml each of the reagent a-picolinic acid and the cyanide with stirring in the order stated, and the volume of the solution was made up to 50 ml in a volumetric flask. Absorption measurements at 440 m/c (Filter 44) were carried out on a portion of the orange yellow coloured solution so prepared (cf. Part 1 of the series). After the iron determination, a measured aliquot from the volumetric flask was taken in a separating funnel and treated with the acetic acid solution to adjust the pIr of the aliquot to 4. I ml of the 8-oxine solution in chloroform was added to the solution followed by 5 ml portion of distilled chloroform. The contents were shaken for a few minutes, the excess pressure being released by rcmoving the stopper. The two layers are allowed to separate and the chloroform layer is run in a stoppered flask containing a few grams (2 g) of fused calcium chloride. The extraction with the chloroform solution is repented till the chloroform layer is cdlourless. After drying, the chloroform solution was made up to 50 ml with some extra chloroform and the optical density of the yellow coloured aluminiumoxine complex solution was measured at 400 rnp (Filter 40), using blank solution as the reference solution. Results arc given in Table I. Rcfercnccs
p. 387.
A.
386
K.
MAJUMDAR,
B.
SEN
VOL.
8
(1953)
To calculate the results, the “calibration factor” was determined by meascring the transmittancy of a number of known solutions of iron and aluminium treated in the same way as described above. The scale readings of the unknown solutions were multiplied by the “calibration factor” for the concentrations of the known. TABLE .
- -_-_. Iron prcscnt. cc& ----_. ._.
..--..-. - - -..- ----Aluminium present. pg .______ _. _ __-. __. _ ___.._
100
IO0
100
200
IO0
4oo
100
I ..-.I-_-. Iron -.
- . .--.found. Aluminium c(g c(g .-_. ___._.--__-_---_ IO0 100
20
LOO
50 100
100
IO0
;: 20
100
-.-.
;o"
100
100
.
100 100 100
19 39 50
100 100 GO
40
99
203 396 4oo -
100 100
z: IO0
TOO
- ---_
_...- _ _. found.
.-_.----_---__--___--__--__-
100
40
IO0
20
___.-. -_._ -_
__-._-_.
._
SUMMARY A very simple, rapid and accurate method for the calorimetric estimation of micro amounts of iron and aluminiuxr from the same solution has been described. The iron is determined in the ferrous state by its orange yellow colour with a-picolinic acid in the presence of an alkali c anide, and aluminium concentration is measured from the yellow colour given by trie chloroform solution of the aluminiumoxine complex after masking the effect due to iron by a-picolinic acid. RESUME Une m&hode de dosage colorimetrique trds simple, rapide et recise, est d&rite, ermettant de determiner Fe et Al dans la meme solution. Le Per est dose B I’btat Perreux par l’acide a-picolinique, en presence de cyanure alcalin (coloration ‘aune orange) et l’aluminium par extraction du complexe aluminium-oxine dans le c &loroforme (coloration jaunt) apres mssquage du fer par l’acide a-picolinique. ZUSAMMENFASSUNG Es wurde einc sehr einfache schnelle und enaue Methode zur kolorimetrischen Bestimmung von Mikromengcn Eisen und A Puminium in der gleichen Losung beschrieben. Eisen wird als zweiwertiges Eisen durch die orangegelbe Farbe mit u-Picolinslure in Gcgcnwart von Alkalicyanid bestimmt. Die Aluminiumkonzentration wird durch die gelbe Farbe bestimmt, die eine Chloroformldsung des Aluminiumoxinkomplexes nach dem Maskieren des Eisens mit a-Picolins8ure gibt. I?eferences p. 387.
VOL.
8 (1953)
a-PICOLINIC
ACID
AS
COLORIMETRIC
REAGENT
387
III
1 A. Ii, MAJUMDAR AND 13. SET’, :fmzi. Chrm. Arlrt. 8 (19.53) 3Gt). 378. * J. T. \VOORS AP*'D M. G. M'IL~LI,OS. Imll. Ilvg. C'h~m. .*I lrttl. I:'d, 13 (1941) 551. 8 H. W. SWANK AND R/I. G. MELLOX, fwi. IZ*zg.C'lrcru., :Junl. Jlrl., xo (1938) 7. 4 \V. B. FORTUNE AND IQ. G. MELAOS, itrrt’. E’:?t$. CTItctt~.,Awrl. Ed., IO (1938) 60. * L. G. SAYWELL AND ES. B. CUNNINGHAS%, Imti. l
Received
January
27th,
~953