Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Antiprotozoal (veterinary).
DEFINITION
Decoquinate Premix contains Decoquinate.
The premix complies with the requirements stated under Premixes and with the following requirements.
Content of decoquinate, C24H35NO5
95.0 to 105.0% of the stated amount.
IDENTIFICATION
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Heat a quantity containing 0.1 g of Decoquinate with 40 mL of chloroform for 20 minutes on a water bath under a reflux condenser, cool and filter.
(2) 0.25% w/v of decoquinate BPCRS in chloroform.
CHROMATOGRAPHIC CONDITIONS
(a) Use as the coating silica gel GF254.
(b) Use the mobile phase as described below.
(c) Apply 10 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry in air and examine under ultraviolet light (254 nm).
MOBILE PHASE
30 volumes of ethanol (96%) and 70 volumes of chloroform.
CONFIRMATION
The principal spot in the chromatogram obtained with solution (1) corresponds in position and colour to that in the chromatogram obtained with solution (2).
ASSAY
Heat a quantity containing 0.2 g of Decoquinate with 50 mL of chloroform in an apparatus for the continuous extraction of drugs, Appendix XI F, for eight reflux cycles. Cool and add sufficient chloroform to produce 100 mL. Dilute 5 mL to 100 mL with absolute ethanol. To 5 mL add 10 mL of 0.1M hydrochloric acid and dilute to 100 mL with absolute ethanol. Measure the absorbance of the resulting solution at the maximum at 265 nm, Appendix II B. Dissolve 50 mg of decoquinate BPCRS in 10 mL of hot chloroform and, keeping the solution warm, add slowly 70 mL of absolute ethanol. Cool, dilute to 100 mL with absolute ethanol and immediately dilute 10 mL to 100 mL with absolute ethanol. To 10 mL of the resulting solution add 10 mL of 0.1M hydrochloric acid and dilute to 100 mL with absolute ethanol. Calculate the content of C24H35NO5 in the premix from the absorbances obtained using the declared content of C24H35NO5 in decoquinate BPCRS.
