Poloxamer USP Testing

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Introduction

Poloxamers (aka Pluronics) are a class or non-ionic surfactants made from ethylene and propylene oxides. The figure below shows the block copolymer structure. USP/NF specifies 5 different types of poloxamers with different chain lengths for a and b.

Wikipedia - Poloxamer

Exova (WCAS) provides a full range of chemical testing services for Poloxamer according to USP/NF, EP, and DAC. USP tests include:

Identification by FTIR
Average Molecular Weight
Wt% Oxyethylene by NMR <761>
pH <791>
Unsaturation
Heavy Metals <231> I
Limit of Free Ethylene Oxide, Propylene Oxide, and 1,4-Dioxane
Residual Solvents <467>

For a quotation...

NMR of Poloxamer

One of the more interesting tests we perform on Poloxamer is weight percent oxyethylene by nuclear magnetic resonance (NMR) spectroscopy. Exova operates a Bruker Avance III 500 MHz system under GMP quality assurance.

From the ¹H NMR spectrum, the ratio of the CH₃protons for the methyl groups on the oxypropylene chain (at ~1.1 ppm) to the -CH₂ protons on both the oxypropylene and oxyethylene chains (3.2-3.8 ppm) provides a measure of the weight % oxyethylene.

For more information on NMR ...

¹H NMR Spectrum of Poloxamer-188

Poloxamer 188 1H NMR, weight % oxyethylene

Reference:	National Formulary 27 through Supplement 2
Monograph:	Poloxamer
Sample ID:	Poloxamer-407

Analysis:		Specification	Result	Pass/Fail
Identification by <197F>		Conforms to reference standard	Conforms to reference standard	Pass
Average Molecular Weight		9840 - 14600	10080	Pass
Weight Percent Oxyethylene				Pass
Nuclear Magnetic Resonance <761>		73.2 ! 1.7	72.8
Unsaturation		0.031 - 0.065 mEq/g	0.054 mEq/g	Pass
Ethylene Oxide, Propylene Oxide, and 1,4-Dioxane				Pass
Ethylene Oxide		NMT 1 ppm	NMT 1 ppm
Propylene Oxide		NMT 5 ppm	NMT 5 ppm
1,4-Dioxane		NMT 5 ppm	NMT 5 ppm
Heavy Metals <231> I		NMT 0.002%	NMT 0.002%	Pass

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Introduction

NMR of Poloxamer

An Example Report