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Table 8 Comparison of various methods for determination of CAA with published results in the literature

From: Quantitative determination of cyanoacetic acid content in teriflunomide drug substance by ion chromatography using conductivity detector






Diazosulfanic acid + sodium hydroxide solution, read at 490 nm

Read against reagent blank and test solution


Calorimetric method

Diazosulfanic acid + sodium carbonate solution

Read against reagent blank and test solution


Gas chromatography method

Column, 1 m (3–4) mm; sorbent, 10% poly(ethylene glycol) sebacate on Polysorb I; temperature regime: column thermostat, 100 °C; DTP detector, 150 °C; evaporator, 300 °C; detector current, 190 mA; carrier gas (helium) flow rate, 30 ml/min; sample volume 0.4 μl

Recovery ranges from 97.95 to 101.1%


High-performance liquid chromatography

C18 column(250 mm × 4.6 mm, 4 μm), mixture of 0.02 mol/L potassium dihydrogen phosphate and methanol (volume ratio of 90:10) with pH 2.0, UV detection at 228 nm

Linear correlation of the method was 0.9999, the standard deviation was 0.20 and the average recovery was 99.78%.


Ion chromatography

The column was a METROSEP A SUPP 5, 6.1006.530, (250 mm × 4.0 mm) 5 μm particles of Polyvinyl alcohol with quaternary ammonium groups. The mobile phase has consists of 504 mg of sodium bicarbonate and 53 mg of sodium carbonate in 1000 mL of water, conductivity detector

LOD and LOQ 33 μg/g and 101 μg/g respectively, average recovery 98.6% to 100.1% and linearity 0.999

Present work