Use of microcosmic salt as a new titrant for the microdetermination of acetic and glycolic acids

MICROCHEMICAl

JOURNAI

15,

171-172 (1970)

Use of Microcosmic Microdetermination

Salt as a New Titrant for the of Acetic and Glycolic Acids A. K. SAXENA

Tn earlier publications from this laboratory, methods were suggested for the microdetermination of some organic acids such as sulfanilic(-?), iodoacetic, and oxalic(41 acids, etc., by titration with a microcosmic salt solution. In the present paper a similar procedure is described for the microdetemination of acetic and glycolic acids. It is observed that the results are concordant and precise, and compare well with other methods (1, 2, 5) proposed earlier. EXPERIMENTAL

METHODS

Reagents used. Acetic acid (A.R.B.D.H.);

glycolic acid (Riedel 57% ), microcosmic salt (E Merck), and bromcresol purple (B.D.H.). Procedure. To a given solution of acid, add some distilled water to raise its volume to about IS ml, followed by I or 2 drops of 0.1% solution of bromcresol purple indicator. The solution is yellow at this point. Now titrate it with a standardized microcosmic salt solution until the yellow color is completely discharged and the solution is a faint purple. TABLE

1

MI<‘KCJDL~I~R~~~NATI[IN ot‘ AC.I:TK ACID ~.. ..~ Vol or soln (ml, Acetic acid cmg) Sample 110.

I 2 3 4 ___-__.

0.001 M Acetic acid taker1

Microcosmic salt 0.001 M

Found

5 00 2.50 1.00 0.50

5.0x -7.48 0.94 0.56

0.305 0. 149 0.056 0.034 _I~-___-

--

171

Theoretical value 0.300 0. 150 O.OhO 0.030 -l.

Error (w) 0.005 O.oi~l 0.004 0.004 _.--

172

SAXENA TABLE MICRODETERMINATION

2 OF GLYCOLIC

Vol of soln (ml) Sample no.

0.001 M Glycolic acid taken

ACID

Glycolic acid (mg)

Microcosmic salt 0.001 M

Found

Theoretical value

0.383 0.229 0.074 0.039

0.380 0.228 0.076 0.038

1

5.00

2 3 4

3.00

5.04 3.06

1.00

0.98

0.50

0.52

Error (mg) 0.003

0.001 0.002

0.001

RESULTS

The results are given in Tables 1 and 2; acids were estimated over a range of 0.380-0.030 mg. The results are concordant and precise. SUMMARY The acetic and glycolic acids were determined in micro quantities with a titrant, i.e., microcosmic salt solution, bromcresol purple was used as indicator. Estimations were carried out in the range of 0.380-0.030 mg, with a maximum error of to.005 mg. ACKNOWLEDGMENT The author is grateful to Drs. B. B. L. Saxena and M. N. Srivastava for their kind guidance and to U.G.C. (Govt. of India) for providing financial assistance. REFERENCES 1.

Hurka,

determination of acetic acid. Mikrochem. (1943). Kniewalt, J., Mildner, P., and Markovic, T., Determination of aliphatic mono-, di- tri-carboxylic acids by the redox-kinetic effect. Arjziv. Tehnol. 2, 71-7.5 (1964). Saxena, A. K., Use of microcosmic salt as a new titrant for the microdetermination of sulfanilic acid. Microchem. J. 14, 430-431 (1969). Saxena, A. K., Use of microcosmic salt as a new titrant for the microdetermination of iodoacetic and oxalic acids. Microchem. J. 14, 000 (1969). Sharma, N. N. and Mehrotra, R. C., Cerate oxidimetry. I. Oxidation of formic, glycolic, malic, malonic and tartaric acids. Anal. Chin Acta 11, VW.

2.

3. 4.

5.

W., Comparative

titrimetric

Mikrochim.

31, S-8

417-427

(1954).

Actn