Apr. 8, 2010  10  US 2010/0087650 Al  [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.  ( 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  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  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.  TABLE 15  TABLE 14-continued  Example 8  ND-Not detected, NE-Not evaluated  Anion removal(%)  Cis-cis isomer recoven:: (%)  No. Buffer  Step 1  Step 2  Step 3  Step 1  Step 2  Step 3  2  20 mM NH$_{4}$•coo-;  79.02  6.04  1.34  1.23  71.4  0.2  HCOOH, pH - 3.5  3  20 mM Na•CH 3 Coo-;  85.73  15.66  ND  10  90.8  ND  NaCOOH, pH - 3.5  4  20 mM Na•NO 3  -/HNO3,  NE  NE  NE  ND  98.23  0.2  pH - 3.0  5  20 mM CaBriHBr  100.42  35  ND  ND  103.8  0.1  pH - 3.0  Cone. of  Loading weight of  sample solution  Loading  Loading weight  the cis-cis isomer  (mg/ml)  volume (ml)  (mg/column)  (mg/column)  30.7  30.7  17.2  30.7  30.7  17.2  30.7  2  61.4  34.4  30.7  2  61.4  34.4  Total  184.2  103.2  % of cis- cis isomer  99.1  99.6  99.6  99.5 