PEI: New Methods and Updated Brochure

Many customers have come to us with difficulties in analyzing Polyethylenimine (PEI). It is not a simple polymer to analyze with HPLC for a variety of reasons, including:

– PEI is a mixture of different molecules with a large variety of differing lengths and branching structures
– PEI has multiple charges in acidic and neutral pH solutions, which are typically used for HPLC
– PEI has no UV chromophores so it is difficult to detect using a standard UV-Vis detector
– PEI irreversibly binds to silica-based columns, limiting the type of adsorbents that can be used for analysis
– PEI peak can coelute with other peptides or proteins

SIELC Technologies has developed two novel approaches to analyze PEI that allow users to overcome these issues:

1) SIELC’s PEI column utilizes both Size Exclusion and Ion Exclusion Chromatography. This method can be modified for use with UV or ELSD/CAD/ESI detection modes.

2) For applications that need better selectivity to separate peptides and proteins from PEI, a method using our new BIST™ technology and BIST™ columns was developed.For a deeper exploration into PEI analysis using our PEI and BIST™ columns, as well as for help removing PEI sample carryover, check out our new brochure

SIELC’s research team is constantly developing new methods for applications requested by our customers. Following these tested methods saves you time and eliminates the hassle of trial and error. Some of our new applications include:

4-(2-Aminoethyl) benzenesulfonamide (Primesep 100),
Bromhexine and Ambroxol (Primesep 200),
Carnosine (beta-alanyl-L-histidine) (BIST B),
Cefuroxime (Primesep 100),
Dextromethorphan (Primesep 100),
Fluorouracil and Flucytosine (Primesep 100),
Glucose and Lysine (Primesep 100),
Iodide (Primesep B),
Polyethylenimine with ELSD (PEI),
Terbutaline Sulfate, Guaifenesin and Ambroxol (Primesep 200),
Trometamol (Tris) and Sodium (Primesep 100).

As always, if you would like more information about any of our columns or methods, feel free to contact us at