_____________________________________________________________________________________________________ *Corresponding author: E-mail: nichogm_2006@yahoo.com; International Research Journal of Pure & Applied Chemistry 13(3): 1-9, 2016; Article no.IRJPAC.29657 ISSN: 2231-3443, NLM ID: 101647669 SCIENCEDOMAIN international www.sciencedomain.org Optimized Preparation of Silver Nanoparticles from Polyethylene Glycol and Formaldehyde Nichrous Mlalila 1,2* , Hulda Swai 1 , Askwar Hilonga 3 and Dattatreya M. Kadam 2 1 School of Life Science and Bioengineering, Nelson Mandela African Institution of Science and Technology, P.O.Box 447, Arusha, Tanzania. 2 ICAR-Central Institute of Post-Harvest Engineering and Technology (ICAR-CIPHET), P.O. PAU, Ludhiana 141 004, Punjab, India. 3 Department of Materials Science and Engineering, Nelson Mandela African Institution of Science and Technology, P.O.Box 447, Arusha, Tanzania. Authors’ contributions This work was carried out in collaboration between all authors. The design of work was carried under direction of author DMK. Author NM involved in synthesis of the work and writing layout of the manuscript. All authors involved in writing, editing and proofing the manuscript and approved the final manuscript. Article Information DOI: 10.9734/IRJPAC/2016/29657 Editor(s): (1) Martin Kroger, Department of Materials, Computational Polymer Physics, Swiss Federal Institute of Technology (ETH Zürich), Switzerland. Reviewers: (1) Betty Enerva, Taguig City University, Philippines. (2) Noriah Bidin, Fakulti Sains Universiti Teknologi, Malaysia. Complete Peer review History: http://www.sciencedomain.org/review-history/17281 Received 22 nd September 2016 Accepted 11 th October 2016 Published 19 th December 2016 ABSTRACT The purpose of this work was to study the effect of various process and formulation parameters on size and shapes of silver nanoparticles (AgNPs) based on surface plasmon resonance (SPR). AgNPs were prepared by chemical reduction using formaldehyde (HCHO) as reducing agent and capped by polyethylene glycol (PEG). Effect of several processing variables including the concentration and volume of capping agent and reaction time is reported. The size of monodispersed nanoparticles was between 30-100 nm and was stable for three months at both room temperature and 4°C. Keywords: Capping agent; full width at half-maximum; particle size; surface plasmon resonance. Original Research Article