Phloroglucinol Dihydrate CAS 6099-90-7 Assay 99.0~101.0% EP Standard

Phloroglucinolum dihydricum
C6H6O3,2H2O Mr 162.1
[6099-90-7]
DEFINITION
Benzene-1,3,5-triol dihydrate.
Content: 99.0 per cent to 101.0 per cent (dried substance).
CHARACTERS
Appearance: white or almost white powder.
Solubility: sparingly soluble in water, freely soluble in ethanol (96 per cent), practically insoluble in methylene chloride.
IDENTIFICATION
A. Infrared absorption spectrophotometry (2.2.24).
Preparation: previously dry the substance to be examined in an oven at 105℃.
Comparison: anhydrous phloroglucinol CRS.
B. Thin-layer chromatography (2.2.27).
Test solution. Dissolve 0.20 g of the substance to be examined in methanol R and dilute to 10 mL with the same solvent.
Reference solution. Dissolve 0.20 g of anhydrous phloroglucinol CRS in methanol R and dilute to 10 mL with the same solvent.
Plate: TLC silica gel F254 plate R.
Mobile phase: anhydrous formic acid R, hexane R, ethyl acetate R (2:37.5:62.5 V/V/V).
Application: 10 μL.
Development: over 2/3 of the plate.
Detection: examine in ultraviolet light at 254 nm.
Results: the principal spot in the chromatogram obtained with the test solution is similar in position and size to the principal spot in the chromatogram obtained with the reference solution.
C. Loss on Drying (see Tests).
TESTS
Solution S. Dissolve 2.50 g in ethanol (96 per cent) R and dilute to 25 mL with the same solvent.
Appearance of solution. Solution S is clear (2.2.1) and not more intensely coloured than reference solution BY5 (2.2.2, Method II).
pH (2.2.3): 4.0 to 6.0.
Dilute 10 mL of solution S to 100 mL with carbon dioxide-free water R.
Related substances. Liquid chromatography (2.2.29). Prepare the solutions immediately before use and protect from light.
Solvent mixture : mobile phase B, mobile phase A (10:90 V/V).
Test solution. Dissolve 50 mg of the substance to be examined in the solvent mixture and dilute to 10.0 mL with the solvent mixture.
Reference solution (a). Dilute 1.0 mL of the test solution to 100.0 mL with the solvent mixture. Dilute 1.0 mL of this solution to 10.0 mL with the solvent mixture.
Reference solution (b). Dissolve 6 mg each of resorcinol R (impurity B), phloroglucide R (impurity D) and pyrogallol R (impurity A) in 10 mL of the solvent mixture, add 2 mL of the test solution and dilute to 20.0 mL with the solvent mixture. Dilute 1.0 mL of this solution to 50.0 mL with the solvent mixture.
Reference solution (c). Dissolve 4 mg each of pyrogallol R (impurity A), phloroglucide R (impurity D), benzene-1,2,4-triol R (impurity E), 2,6-dichlorophenol R (impurity I), 4-chlororesorcinol R (impurity K) and 3,5-dichloroaniline R (impurity L) in 10 mL of the solvent mixture and dilute to 20.0 mL with the solvent mixture.
Reference solution (d). Dissolve 10 mg of the substance to be examined in 10 mL of the solvent mixture, add 1.0 mL of reference solution (c) and dilute to 20.0 mL with the solvent mixture.
Column:
- size: l = 0.25 m, Ø = 4.0 mm;
- stationary phase: end-capped octadecylsilyl silica gel for
chromatography with embedded polar groups R (5 μm)
Mobile phase :
-mobile phase A: 1.36 g/L solution of potassium dihydrogen phosphate R previously adjusted to pH 3.0 with phosphoric acid R;
-mobile phase B: acetonitrile R;
Time (min) Mobile phase A (per cent V/V) Mobile phase B (per cent V/V)
0 - 9 100 0
9 - 15 100 → 50 0 → 50
15 - 25 50 → 20 50 → 80
25 - 30 20 80
Flow rate: 1.0 mL/min.
Detection: spectrophotometer at 265 nm.
Injection: 20 μL of the test solution and reference solutions (a), (b) and (d).
Identification of impurities: use the chromatogram obtained with reference solution (d) to identify the peaks due to impurities A, D, E, I, K and L.
Relative retention with reference to phloroglucinol
(retention time = about 12 min): impurity E = about 0.7;
impurity A = about 0.9; impurity D = about 1.3;
impurity B = about 1.35; impurity K = about 1.5;
impurity I = about 1.8; impurity L = about 2.0.
System suitability: reference solution (b):
-resolution: minimum 2.5 between the peaks due to impurity A and phloroglucinol; minimum 4.0 between the peaks due to impurities D and B.
Limits:
-correction factors: for the calculation of content, multiply the peak areas of the following impurities by the corresponding correction factor: impurity A = 0.6;
impurity D = 0.2; impurity E = 0.7; impurity I = 0.6;
impurity K = 0.6; impurity L = 0.4;
-impurities A, D, E, I, K, L: for each impurity, not more than
1.5 times the area of the principal peak in the chromatogram
obtained with reference solution (a) (0.15 per cent);
-unspecified impurities: for each impurity, not more than the area of the principal peak in the chromatogram obtained with reference solution (a) (0.10 per cent);
-total: not more than 3 times the area of the principal peak in the chromatogram obtained with reference solution (a) (0.3 per cent);
-disregard limit: 0.5 times the area of the principal peak in
the chromatogram obtained with reference solution (a) (0.05 per cent).
Chlorides (2.4.4): maximum 200 ppm.
Dilute 2.5 mL of solution S to 15 mL with water R.
Sulfates (2.4.13): maximum 500 ppm.
Dilute 3 mL of solution S to 15 mL with distilled water R.
Loss on Drying (2.2.32): 20.0 per cent to 23.0 per cent, determined on 1.000 g by drying in an oven at 105℃.
Sulfated ash (2.4.14): maximum 0.1 per cent, determined on 1.0 g.
ASSAY
Dissolve 0.600 g in 50 mL of water R. Titrate with 1 M sodium hydroxide, determining the end-point potentiometrically (2.2.20).
1 mL of 1 M sodium hydroxide is equivalent to 63.05 mg of C6H6O3.
STORAGE
Protected from light.
IMPURITIES
Specified impurities: A, D, E, I, K, L.
Other detectable impurities (the following substances would, if present at a sufficient level, be detected by one or other of the tests in the monograph. They are limited by the general acceptance criterion for other/unspecified impurities and/or by the general monograph Substances for pharmaceutical use (2034). It is therefore not necessary to identify these impurities for demonstration of compliance. See also 5.10. Control of impurities in substances for pharmaceutical use): B, O.
A. benzene-1,2,3-triol (pyrogallol),
B. benzene-1,3-diol (resorcinol),
D. 2,3',4,5',6-biphenylpentol (phloroglucide),
E. benzene-1,2,4-triol,
I. 2,6-dichlorophenol,
K. 4-chlorobenzene-1,3-diol (4-chlororesorcinol),
L. 3,5-dichloroaniline,
O. 4,6-dichlorobenzene-1,3-diol (4,6-dichlororesorcinol).