TEST 1
Buffer solution
Prepare a solution in water containing 3.85 g per L of 1-pentanesulfonic acid, 2.9 g per L of sodium chloride, and 1% (v/v) of 1 N sulfuric acid.
Mobile phase
Prepare a filtered and degassed mixture of Buffer solution and acetonitrile (95:5).
System suitability solution
Dissolve accurately weighed quantities of citric acid and succinic acid in Mobile phase to obtain a solution containing about 0.5 mg of each per mL.
Standard solution
Dissolve an accurately weighed quantity of 
USP Succinylmonocholine Chloride RS in 
Mobile phase, and dilute quantitatively, and stepwise if necessary, with 
Mobile phase to obtain a solution having a known concentration of about 0.05 mg per mL.
 
Test solution
Transfer about 100 mg of Succinylcholine Chloride, accurately weighed, to a 10-mL volumetric flask, and dissolve in and dilute with Mobile phase to volume.
Chromatographic system (see Chromatography 
621
)
The chromatograph is equipped with a 214-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute. Samples are maintained at a temperature of about 4

 during the analysis. Chromatograph the 
System suitability solution, and record the peak responses as directed for 
Procedure: the relative retention times are about 0.22 for succinic acid, 0.32 for the doublet of peaks quantitated as a single component, 0.49 for succinylmonocholine chloride, and 1.0 for succinylcholine chloride; the resolution, 
R, between citric acid and succinic acid is not less than 2.9; and the relative standard deviation for replicate injections is not more than 3.0%.
 
Procedure
Separately inject equal volumes (about 50 µL) of the 
Standard solution and the 
Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Begin integration after the edetate disodium peak, if present (retention time is about 3.5 minutes). Calculate the percentage of each impurity in the portion of Succinylcholine Chloride taken by the formula: 
10C(ri / rS)F
in which 
C is the concentration, in mg per mL, of 
USP Succinylmonocholine Chloride RS in the 
Standard solution; ri is the peak area for each impurity obtained from the 
Test solution; rS is the succinylmonocholine chloride peak area obtained from the 
Standard solution; and 
F is the response factor (0.63 for succinic acid): not more than 0.1% of succinic acid is found; not more than 0.4% of the doublet of peaks quantitated as a single component is found; not more than 0.4% of succinylmonocholine chloride is found; and not more than 0.2% of any other individual impurity is found.
 
 
TEST 2 (Limit of choline)
Solution A
Prepare a solution in water containing 5% (v/v) of acetonitrile and 5% (w/v) of 0.1 M 1-hexanesulfonic acid.
Solution B
Prepare a solution of acetonitrile and water (1:1).
Mobile phase
Use variable amounts of 
Solution A and 
Solution B as directed for 
Chromatographic system. Make adjustments if necessary (see 
System Suitability under 
Chromatography 
621
).
 
System suitability solution
Dissolve an accurately weighed quantity of 
USP Choline Chloride RS and sodium chloride in water; and dilute quantitatively, and stepwise if necessary, with water to obtain a solution containing 0.05 mg per mL and 

0.01
USP29 mg per mL, respectively. 
 
Standard stock solution
Dissolve an accurately weighed quantity of 
USP Choline Chloride RS in water; and dilute quantitatively, and stepwise if necessary, with water to obtain a solution containing 0.5 mg per mL.
 
Standard solution
Dilute 1 mL of the Standard stock solution with water to 50 mL.
Test solution
Transfer an accurately weighed quantity of Succinylcholine Chloride, about 50 mg, to a 25-mL flask. Dissolve in and dilute with water to volume.
Chromatographic system (see Chromatography 
621
)
The ion chromatograph is equipped with a suitable device for chemical suppression, a conductivity detector at 30 µS, and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The eluant flow is about 1 mL per minute, and uses a suitable regenerant flow rate at 50 mA output. The chromatograph is programmed as follows. 
Time   (minutes) | 
Solution A 
 (%) | 
Solution B 
 (%) | 
 
 Elution | 
| 015 | 
100 | 
0 | 
isocratic | 
| 1516 | 
100®0 | 
0®100 | 
linear gradient | 
| 1625 | 
0 | 
100 | 
isocratic | 
| 2527 | 
0®100 | 
100®0 | 
linear gradient | 
| 2740 | 
100 | 
0 | 
isocratic | 
 
Chromatograph the 
System suitability solution, and record the peak responses as directed for 
Procedure: the resolution, 
R, between sodium and choline is not less than 2.0; and the relative standard deviation for replicate injections is not more than 3.0%.
 
Procedure
Separately inject equal volumes (about 50 µL) of the 
Standard solution and the 
Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of choline in the portion of Succinylcholine Chloride taken by the formula: 
37.5C(rC / rS)
in which 
C is the concentration, in mg per mL, of 
USP Choline Chloride RS in the 
Standard solution; and 
rC and 
rS are the choline peak areas obtained from the 
Test solution and the 
Standard solution, respectively: not more than 0.3% of choline is found, 

and
USP29 not more than 1.5% of total impurities is found, the results for 
Test 1 and 
Test 2 being added.