Copyright © Alhassan S. I et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Chemistry, 8 (1) (2020) 128-140 International Journal of Advanced Chemistry Website: www.sciencepubco.com/index.php/IJAC Research paper Comparative viscometric study of pure and acetylated gum Arabic using different plot methods Alhassan S. I 1 *, Sule S. Y 1 , Murtala R 1 , Rasheed H. I 2 , Baso A. A 1 , Sheshe F. A 2 , Jafar S. C 3 1 Kano University of Science and Technology, Wudil, Kano, Nigeria. 2 Bayero University Kano, Nigeria 3 Ahmadu Bello University,Zaria, Nigeria *Corresponding author E-mail:saniidris2012@gmail.com Abstract Acetylation of gum Arabic was achieved using acetic anhydride as solvent. The ester group formed was confirmed by FTIR spectra having absorption band of 750 cm-1 – 700 cm-1. Viscometric study of the pure and acetylated samples was carried out. Relative viscosity of acetylated gum was found to be higher than that of the pure gum. Intrinsic viscosity was determined for the two samples using different plot methods taking Huggin’s plot as standard. The intrinsic viscosity was found to be 86.43 cm3/g and 64.59 cm3/g for acetylated and pure gum arabic respectively. Relative errors of other methods for the two samples was compared to that of Huggins and the plots that are most comparable to Huggins with relative errors less than 5% are; Martin, Lyon-Tobolsky, Staudinger-Heuer, Maron-Reznik and our proposed method. The proposed method which was a modification of the Kreiser method gave relative error less than 2 %, for both pure and modified gum. Whereas the Kreiser method gave relative error greater than 15 % for both methods. The critical concentration for the samples was found to be 0.0116 g/cm3 and 0.0155 g/cm3 for acetylated and pure gum respectively. This shows that there was no molecule- molecule entanglements during viscosity measurements. Keywords: Intrinsic Viscosity; Acetylation; Gum Arabic. 1. Introduction Gum Arabic exudate is gummy, dry and edible. It is usually obtained from stems and branches of Acacia senegal and Acacia seyal that have high content of non-viscous soluble fibre (Williams, 2000). It is a salt of complex polysaccharides that is neutral or slightly acidic in nature, containing Ca 2+ , Mg 2+ and K + . Its most distinguishing character among other gums is that it is extremely soluble in water. The exudate is found mainly in unhealthy trees that are affected by diseases, drought or poor nutrition. The gum comes out through wounds carved in the bark of the tree in liquid drops, which then becomes hard with time. The tree’s taxonomic classification is genus; Acacia, subfamily; Mimosoidene, family; leguminosae (Smolinske, 1992). The gum itself comprise of different materials but may be separated in to three major parts. 88.4% of the gum is arabinogalactan with 0.35% protein content and has molecular weight of 3.8 × 10 5 Da. 10.4% is arabinogalactan protein with 11.4% protein and 4.5 × 10 6 Da molecular weight. The third part (1.2%) is glycoprotein with 47.3% protein content with 2.5×10 5 Da molecular weight (Randell et al., 1989). Gums obtained from acacia species have high molecular weight (Baldein et al, 1999), are used as gels and thickeners (Savary et al., 2009), have emulsifying properties (Huang et al, 2001; Islam et al., 1997), stabilization properties (Dickinson, 2001) and can be used for micro- encapsulation (Renard et al, 2002). It can also be used in pharmaceutical industries ((Nasir et al, 2010), has biotechnology applications (Ben-Zion and Nussinovitch, 1997) and as an adhesive (Cochrane, 1996) Viscometry is an analytical method used to characterize polymer properties in dilute solutions. It allows fast and very simple way of determining structure, polymer concentration, polymer chain dimensions, molecular weight, and other thermodynamic properties of a polymer in solution (Kulicke and Clasen 2004). Viscosity can be defined as resistance to flow, reflecting the frictional forces of all molecules (of both solute and solvent) present in solution. Capillary viscometers commonly measure the kinematic viscosity, which is the ratio of viscosity to the density of solution. To measure viscosity using a capillary viscometer, a certain amount of the polymer solution is placed in the capillary that has two marks at different levels. The flow time for the solution to pass between two lines marked in the viscometer is proportional to the kinematic viscosity of the solution. The viscosity of a solution is expressed as the sum of viscosity of the dissolved polymer and the viscosity of the solvent (Kulicke and Clasen 2004). Relative viscosity therefore, is defined as the ratio of solution viscosity to solvent viscosity (Kulicke and Clasen 2004). In