Basic Requirements: A. Degree in physical sciences, life sciences, or engineering that includes 30 semester hours in chemistry, supplemented by course work in mathematics through differential and integral calculus, and at least 6 semester hours of physics. OR B. Combination of education and experience: Course work equivalent to a major as shown in A above, including at least 30 semester hours in chemistry, supplemented by mathematics through differential and integral calculus, and at least 6 semester hours of physics, plus appropriate experience or additional education. IN ADDITION: To qualify, applicants must have at least one year (52 weeks) of specialized experience equivalent to the GS-9 grade level (ZP-II for NIST). Specialized experience is defined as experience in completely digesting high purity solid materials to gravimetrically prepare calibration solutions in a safe and quantitative manner; elemental analysis measurements, particularly using high precision or high performance Inductively Couple Plasma Optical Emission Spectroscopy; documenting lab work in conformance with a quality system. OR 3 years of progressively higher level graduate education leading to a Ph.D. degree or Ph.D. or equivalent doctoral degree OR A combination of education and specialized experience as defined in the additional requirements Experience refers to paid and unpaid experience, including volunteer work done through National Service programs (e.g., Peace Corps, AmeriCorps) and other organizations (e.g., professional; philanthropic; religious; spiritual; community, student, social). Volunteer work helps build critical competencies, knowledge, and skills and can provide valuable training and experience that translates directly to paid employment. You will receive credit for all qualifying experience, including volunteer experience. The qualification requirements in this vacancy announcement are based on the U.S. Office of Personnel Management (OPM) Qualification Standards Handbook. If requesting reconsideration of your qualification determination, please refer to the following site: Applicant Reconsideration