Diclazuril
C17H9Cl3N4O2 407.64
Benzeneacetonitrile, 2,6-dichloro-
-(4-chlorophenyl)-4-(4,5-dihydro-3,5-dioxo-1,2,4-triazin-2(3H)-yl)-;
(p-Chlorophenyl)[2,6-dichloro-4-(4,5-dihydro-3,5-dioxo-as-triazin-2(3H)-yl)phenyl]acetonitrile
[101831-37-2].
(dye klaz' ue ril).
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C17H9Cl3N4O2 407.64
Benzeneacetonitrile, 2,6-dichloro-
-(4-chlorophenyl)-4-(4,5-dihydro-3,5-dioxo-1,2,4-triazin-2(3H)-yl)-;
(p-Chlorophenyl)[2,6-dichloro-4-(4,5-dihydro-3,5-dioxo-as-triazin-2(3H)-yl)phenyl]acetonitrile
[101831-37-2].DEFINITION
Diclazuril contains NLT 97.0% and NMT 101.0% of C17H9Cl3N4O2, calculated on the dried basis.
IDENTIFICATION
ASSAY
• Procedure
Buffer:
Dissolve 6.3 g of ammonium formate in 800 mL of water, adjust with anhydrous formic acid to a pH of 4.0, and add 200 mL of water.
Solution A:
Acetonitrile, water, and Buffer (3:15:2)
Solution B:
Acetonitrile, water, and Buffer (85:5:10)
Mobile phase:
See the gradient table below.
| Time (min) |
Solution A (%) |
Solution B (%) |
|---|---|---|
| 0 | 100 | 0 |
| 20 | 0 | 100 |
| 25 | 0 | 100 |
| 26 | 100 | 0 |
| 36 | 100 | 0 |
Standard solution:
0.5 mg/mL of USP Diclazuril RS in dimethylformamide
System suitability solution:
0.5 mg/mL of USP Diclazuril System Suitability Mixture RS in dimethylformamide
Sample solution:
0.5 mg/mL of Diclazuril in dimethylformamide
Chromatographic system
Mode:
LC
Detector:
UV 230 nm
Column:
4.6-mm × 10-cm; base-deactivated 3-µm packing L1
Flow rate:
1 mL/min
Column temperature:
35
Injection size:
5 µL
System suitability
Samples:
Standard solution and System suitability solution
Suitability requirements
Resolution:
NLT 1.9 between diclazuril and diclazuril ketone peaks, System suitability solution
Tailing factor:
NMT 1.4, Standard solution
Relative standard deviation:
NMT 2.0%, Standard solution
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C17H9Cl3N4O2 in the portion of Diclazuril taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Diclazuril RS in the Standard solution (mg/mL) |
| CU | = | = concentration of Diclazuril in the Sample solution (mg/mL) |
Acceptance criteria:
97.0%–101.0% on the dried basis
IMPURITIES
Inorganic Impurities
• Residue On Ignition 
281
:
NMT 0.1%
281:
NMT 0.1%
Organic Impurities
• Procedure 1: Residual Solvents 467
467
Acceptance criteria:
NMT 4000 ppm of N,N-dimethylformamide
• Procedure 2
Buffer, Solution A, Solution B, Mobile phase, Standard solution, System suitability solution, Sample solution, and Chromatographic system:
Proceed as directed in the Assay.
Analysis
Samples:
Standard solution and Sample solution
Calculate the area percentage of each impurity, relative to diclazuril, in the portion of Diclazuril taken:
Result = (rU/rS) × (CS/CU) × (1/F) × 100
| rU | = | = peak response of each impurity from the Sample solution |
| rS | = | = peak response of diclazuril from the Standard solution |
| CS | = | = concentration of USP Diclazuril RS in the Standard solution (mg/mL) |
| CU | = | = concentration of Diclazuril in the Sample solution (mg/mL) |
| F | = | = relative response factor (see Impurity Table 1) |
Acceptance criteria
[Note—Disregard any peak observed in the blank. The reporting level for impurities is 0.05%. ]
Individual impurities:
See Impurity Table 1.
Total impurities:
NMT 1.5%
Impurity Table 1
| Name | Relative Retention Time |
Relative Response Factor |
Acceptance Criteria, NMT (%) |
|---|---|---|---|
| 6-Carboxylic acida | 0.62 | 0.85 | 0.50 |
| 6-Carboxamideb | 0.80 | 0.92 | 0.50 |
| Diclazuril | 1.00 | — | — |
| Ketonec | 1.03 | 0.52 | 0.10 |
| 4-Amino derivatived | 1.09 | 0.81 | 0.50 |
| Des-cyano derivativee | 1.16 | 1.1 | 0.50 |
| Trichlorodiphenyl acetonitrilef | 1.24 | 0.71 | 0.50 |
| Any other individual impurity | — | 1.0 | 0.20 |
|
a
(RS)-2-[3,5-Dichloro-4-[(4-chlorophenyl)cyanomethyl]phenyl]-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carboxylic acid.
b
(RS)-2-[3,5-Dichloro-4-[(4-chlorophenyl)cyanomethyl]phenyl]-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carboxamide.
c
2-[3,5-Dichloro-4-(4-chlorobenzoyl)phenyl]-1,2,4-triazine-3,5(2H,4H)-dione.
d
(RS)-2-(4-Amino-2,6-dichlorophenyl)-2-(4-chlorophenyl)acetonitrile.
e
2-[3,5-Dichloro-4-(4-chlorobenzyl)phenyl]-1,2,4-triazine-3,5(2H,4H)-dione.
f
(RS)-2-(4-Chlorophenyl)-2-(2,6-dichlorophenyl)acetonitrile.
|
|||
SPECIFIC TESTS
• Loss On Drying, 731:
Dry a sample at between 100 and 105 under a vacuum for 4 h: it loses NMT 0.5% of its weight.
731:
Dry a sample at between 100 and 105 under a vacuum for 4 h: it loses NMT 0.5% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers, and store at room temperature.
• Labeling:
Label it to indicate that it is for veterinary use only.
• USP Reference Standards 11
11
USP Diclazuril RS 
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USP Diclazuril System Suitability Mixture RS
Contains diclazuril and specified impurities.
Contains diclazuril and specified impurities.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Morgan Puderbaugh, B.S.
Associate Scientific Liaison 1-301-998-6833 |
(SM32010) Monographs - Small Molecules 3 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2878
Pharmacopeial Forum: Volume No. 35(1) Page 73