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A rapid and sensitive sub-micro phosphorus determination
SHORT
COMMUNICATIONS
203
the chelating resin is much more effective than ordinary cation-exchange resins in the recovery of traces of copper from fairly concentrated solutions of ammonium chloride. The chelating resin will probably serve equally well in concentrating traces of other transition metals from solutions of alkali metals and possibly also from the alkalineearth metals. TABLE RECOVERY
OF I .58.
IO’6
iv
COPPER
I FROM
I nf
AMMONIUM
1.0
0.94
0.80
96.7
1.7 1.4
0.94
2.24 I .52
99.0 99.6
4
1.1
o -94
3.01
09.2
2
I.2 I.0
0 0.94
3.28 3.75
98.9 99.1
4.00 5.52 6.00
93.5 93.0 88.5
I
$5
.g4 fl
I.1 I.3
9
I.0
0.94 0.94 0.94
The authors express their gratitude to The Dow Michigan, for financial support of this investigation.
CHLORIDE
.
Chemical
Company,
Midland,
Ra@lt G. Wvigltl Chemicnt Lnbortrtovy, Rzrtgcrs, The State Uknxw’ty
IVm Bnr?tsz~ick, N.J. (U.S./l .) 1
J, P. R.
RICHES,
2 Dowex Chelatirrg 3 17. J. WI~.LCIIER, York, I 958.
Received
Natwe,
Resiir
October
The
A-z, A
158 (rgq6) 96. The Dow Chcmicd
Co.,
Midland,
AMichigan,
195’).
nalyiicul Uses of L=flryle~rediumitIc’lelrurtcclic Acid, Varl Nostrand,
New
xgth, ~$0 And.
A rapid and sensitive sub-micro
China. Acla,
24 (rgG1)
202-203
phosphorus determination
A method for increasing the sensitivity of the phosphorus determination proposed by FISKE AND Su1313~Row~ has recently been introduced by ~ARTLRTTB. Such increased sensitivity is necessary for the examination of small phospholipid fractions from chromatographic columns, and samples of 50 to 15opg organic material can be successfully analysed by this technique. The modification lies” in carrying out the reduction of phosphomolybdate with I-amino-a-naphthol-+sulphonic acid (ANSA) at 100~ instead of at room temperature and in measuring the absorption at 830 m,u instead of at 660 mp. is excellent In our experience the method gives good results: the reproducibility R?lUl.
Grim.
Ada,
24
(rgG1)
203-204
SI-IORT COMMUNICAT:ONS
204
the colour is stable for at least 24 h. A further advantage is that the coloured solution can be diluted with distilled water for measurement in the most sensitive range of the spectrophotometer without loss of proportionality. The &nsitivit’ji is 0.1 ,~g of P (extinction of 0.051 with a 3-cm cuvette). A grave disadvantage of the procedure is, however, that the initial digestion of the sample to give phosphate ion (heating with sulpburic acid at 160-180”) requires 4h h for completion. Increasing the temperature of the digestion mixture is not favourable because of the risk of loss of phosphoric acid (b.p. 213~). Perhydrol added to decrease the reaction time is difficult to remove completely. We have found that perchloric acid, as used by AILEN~ in his method employing amidol as reducing agent, is a better agent for the first step, in that the time necessary for complete digestion can then be reduced to 40 min. (WC have established, incidentally, that amidol is not a suitable reducing agent for the development of the colour at xoo”, since it gives irreproducible results at this temperature.) Samples were heated, after the removal of organic solvents, with 0.2 ml of 70% perchloric acid in tubes (125 x 15 mm) standing to a depth of 30 mm in a thermostatically controlled heating block maintained at 180~. l‘he boiling mixture generally cleared after 12 to 18 min heating, and the reaction was completed by heating for a further 20 min. That the reaction was not complete when the mixture first cleared was established by stopping the reaction at this point by rapid cooling; recoveries of only g4-97% were obtained. Using the described 4o-min digestion procedure, and the method of colour development as recommended by JSAR’rLE-rr, we obtained the following results for a solution of tritotyl-phosphate of high purity (May and Baker Ltd.) in methanol (see Table I).
and
----i’ dddd (pg) 1 .og
1.81 2.54 3.63
TABLE I’ fouml
I (/I#)
1.11
1.8C 2.51
3.64
Xrto”ery
f ‘,‘/“)
101.8
100.0 98.8 100.3
It is suggested that the modification of the digestion procedure described should enhance considerably the usefulness of the sensitive BARTLETT determination. C. J. I;. B~~TTCHER C. M. VAN GENT C. PRIES
Defiartment of Physical Clrcmistvy, L eiden Ukversit y, L&&m (The Netlmdanrls) 1 I-I. C. I?ISKE AND Y. SLI~BAROW, J. Viol. Cirmt., 66 (1925) 375. 2 G. R. BARTLBTT, J. Biot. Chem., 234 (1959) 466. 3 Ii. J. L. ALLEN, Bioclwn. J,. 34 (1940) 858.
Received
October
z6th, I#O .d Wt. Chiln. n&Z,
24 (x961)
203-204
COMMUNICATIONS
203
the chelating resin is much more effective than ordinary cation-exchange resins in the recovery of traces of copper from fairly concentrated solutions of ammonium chloride. The chelating resin will probably serve equally well in concentrating traces of other transition metals from solutions of alkali metals and possibly also from the alkalineearth metals. TABLE RECOVERY
OF I .58.
IO’6
iv
COPPER
I FROM
I nf
AMMONIUM
1.0
0.94
0.80
96.7
1.7 1.4
0.94
2.24 I .52
99.0 99.6
4
1.1
o -94
3.01
09.2
2
I.2 I.0
0 0.94
3.28 3.75
98.9 99.1
4.00 5.52 6.00
93.5 93.0 88.5
I
$5
.g4 fl
I.1 I.3
9
I.0
0.94 0.94 0.94
The authors express their gratitude to The Dow Michigan, for financial support of this investigation.
CHLORIDE
.
Chemical
Company,
Midland,
Ra@lt G. Wvigltl Chemicnt Lnbortrtovy, Rzrtgcrs, The State Uknxw’ty
IVm Bnr?tsz~ick, N.J. (U.S./l .) 1
J, P. R.
RICHES,
2 Dowex Chelatirrg 3 17. J. WI~.LCIIER, York, I 958.
Received
Natwe,
Resiir
October
The
A-z, A
158 (rgq6) 96. The Dow Chcmicd
Co.,
Midland,
AMichigan,
195’).
nalyiicul Uses of L=flryle~rediumitIc’lelrurtcclic Acid, Varl Nostrand,
New
xgth, ~$0 And.
A rapid and sensitive sub-micro
China. Acla,
24 (rgG1)
202-203
phosphorus determination
A method for increasing the sensitivity of the phosphorus determination proposed by FISKE AND Su1313~Row~ has recently been introduced by ~ARTLRTTB. Such increased sensitivity is necessary for the examination of small phospholipid fractions from chromatographic columns, and samples of 50 to 15opg organic material can be successfully analysed by this technique. The modification lies” in carrying out the reduction of phosphomolybdate with I-amino-a-naphthol-+sulphonic acid (ANSA) at 100~ instead of at room temperature and in measuring the absorption at 830 m,u instead of at 660 mp. is excellent In our experience the method gives good results: the reproducibility R?lUl.
Grim.
Ada,
24
(rgG1)
203-204
SI-IORT COMMUNICAT:ONS
204
the colour is stable for at least 24 h. A further advantage is that the coloured solution can be diluted with distilled water for measurement in the most sensitive range of the spectrophotometer without loss of proportionality. The &nsitivit’ji is 0.1 ,~g of P (extinction of 0.051 with a 3-cm cuvette). A grave disadvantage of the procedure is, however, that the initial digestion of the sample to give phosphate ion (heating with sulpburic acid at 160-180”) requires 4h h for completion. Increasing the temperature of the digestion mixture is not favourable because of the risk of loss of phosphoric acid (b.p. 213~). Perhydrol added to decrease the reaction time is difficult to remove completely. We have found that perchloric acid, as used by AILEN~ in his method employing amidol as reducing agent, is a better agent for the first step, in that the time necessary for complete digestion can then be reduced to 40 min. (WC have established, incidentally, that amidol is not a suitable reducing agent for the development of the colour at xoo”, since it gives irreproducible results at this temperature.) Samples were heated, after the removal of organic solvents, with 0.2 ml of 70% perchloric acid in tubes (125 x 15 mm) standing to a depth of 30 mm in a thermostatically controlled heating block maintained at 180~. l‘he boiling mixture generally cleared after 12 to 18 min heating, and the reaction was completed by heating for a further 20 min. That the reaction was not complete when the mixture first cleared was established by stopping the reaction at this point by rapid cooling; recoveries of only g4-97% were obtained. Using the described 4o-min digestion procedure, and the method of colour development as recommended by JSAR’rLE-rr, we obtained the following results for a solution of tritotyl-phosphate of high purity (May and Baker Ltd.) in methanol (see Table I).
and
----i’ dddd (pg) 1 .og
1.81 2.54 3.63
TABLE I’ fouml
I (/I#)
1.11
1.8C 2.51
3.64
Xrto”ery
f ‘,‘/“)
101.8
100.0 98.8 100.3
It is suggested that the modification of the digestion procedure described should enhance considerably the usefulness of the sensitive BARTLETT determination. C. J. I;. B~~TTCHER C. M. VAN GENT C. PRIES
Defiartment of Physical Clrcmistvy, L eiden Ukversit y, L&&m (The Netlmdanrls) 1 I-I. C. I?ISKE AND Y. SLI~BAROW, J. Viol. Cirmt., 66 (1925) 375. 2 G. R. BARTLBTT, J. Biot. Chem., 234 (1959) 466. 3 Ii. J. L. ALLEN, Bioclwn. J,. 34 (1940) 858.
Received
October
z6th, I#O .d Wt. Chiln. n&Z,
24 (x961)
203-204