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ND-Not detected, NE-Not evaluated 

[0083] This example demonstrates a method of product isolation. 

[0084] Fractions of column eluates containing the lR-cis, 1 ’R-cis isomer were collected manually via Hypersil Hyper› prep HS C18 colunm, 250 mm*21.2 mm*15µ, PIN 37115- 125, using the following eluents: 

Eluent A: 20 mM NaNO$_{3 }$ aqueous solution, pH adjusted to 

2.0 with HNO$_{3 }$ 

Eluent B: methanol. 

The gradient was as described in Table 3, and the detection was at 280 nm. The flow rate was 14 ml/min and the cisatra› curium besylate was isolated from the (lR,l’R)-atracurium besylate mixture and analyzed using an HPLC system. The Fractions were combined correspondingly to the 1 R-cis, 1 ’R› cis isomer content, as detailed in Table 15. 

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The fractions were combined ( 400 ml) and mixed with 200 ml of acidified brine (pH=2 with benzenesulfonic acid) and extracted with 150 ml dichloromethane (three consecutive extractions, 50 ml of dichloromethane each extraction). The organic phases were collected, dried with MgSO$_{4 }$ and evapo› rated to dryness to afford residual semi-solid oil (91 mg), which was dissolved in 18 ml water and the pH was adjusted to -3 with benzenesulfonic acid. The aqueous solution was placed into the freeze dryer (in tree glass vials) for 40 hours. The aqueous solution was lyophilized to afford 72 mg of cisatracurium besylate in 60% yield, having purity of 96.3% (by HPLC). 

[0085] All references, including publications, patent appli› cations, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were indi› vidually and specifically indicated to be incorporated by ref› erence and were set forth in its entirety herein. 

[0086] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention 

## Example 8 

( especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "con› taining" are to be construed as open-ended terms (i.e., mean› ing "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indi› cated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language ( e.g., "such as") provided herein, is intended merely to better illuminate the invention and does 

not pose a limitation on the scope of the invention unless otherwise claimed.No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 

[0087] Preferred embodiments of this invention are described herein, including the best mode known to the inven› tors for carrying out the invention. Variations of those pre› ferred embodiments may become apparent to those of ordi› nary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such varia› tions as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all pos› sible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly con› tradicted by context. 

