Agar D, Purified Agar: Appearance: White or light cream pH: 6.0-8.0 (1.5% solution) Molecular weight: N/A Agar A( Cat# G1253) is a purified grade agar, and is completely nutrient-free. It is most useful in defined media formulations where traces of nutrients cannot be tolerated. Some of labs use purified agar as substitute of agarose. Agar is a polysaccharide complex obtained through bleaching and hot water extraction of agarocytes from the red alga Rhodophyceae, found in the Pacific and Indian Oceans and in the Sea of Japan. The genera Gelidium, Acanthopeltis,Ceramium, Pterocladia and Gracilaria predominate in agar production. Agar is composed of about 70% agarose and 30% agaropectin.