trimethoprim

Items

Standard

Results

Appearance

White or yellowish-white powder

White powder

Solubility

Very slightly soluble in water, 

slightly soluble in alcohol.

Very slightly soluble in water, 

slightly soluble in alcohol.

•Identification

A: Melting point

199-203

201.0-201.4

B: Specific absorbance

Max.287nm: 240-250

243

C: IR-spectrum

Complies with reference spectrum

Complies with reference spectrum

D: Chemical reaction

Green fluorescence at 365nm

Green fluorescence at 365nm

Appearance of solution

Not more intensely colored than 

Reference Solution BY7

Less intensely colored than reference solution BY7

Related substances

Method A by HPLC:

Impurity F

≤0.1%

0.05%

Any single impurity

≤0.1%

<0.1%

Total impurities

≤0.2%

<0.2%

Method B by HPLC:

Any single impurity

≤0.1%

<0.1%

Total impurities

≤0.2%

<0.2%

Heavy metals

≤20ppm

<

20ppm

Residual methanol

≤3000ppm

Not detected

Residual DMSO

≤5000ppm

Not detected

Residual acetic acid

≤5000ppm

Not detected

Impurity K(aniline) by GC

≤5ppm

Not detected

Loss on drying

≤0.5%

0.3%

Sulphated ash

≤0.1%

0.02%

Assay 

98.5-101.0%

99.71%

Particle size

100% pass 300 mesh

100% pass 300 mesh