Chemistry Reference
In-Depth Information
• Existing methods may be too expensive, time consuming, or energy inten-
sive, or they may not be easily automated.
• Existing methods may not provide adequate sensitivity or analyte selectiv-
ity in samples of interest.
• Newer instrumentation and techniques may have evolved that provide oppor-
tunities for improved methods, including improved analyte identification or
detection limits, greater accuracy or precision, or better return on investment.
• For legal, compliance, or scientiic reasons, there may be a need for an
alternative or orthogonal method to confirm the analytical data originally
obtained from existing methods.
• Existing method may not be stability indicating.
Before undertaking method development, it is important to have a complete under-
standing of the goals, objectives, and expectations of the method, and then to trans-
late the goals of the method into a method development design and to define the
required analytical performance characteristics for validation.
Goals for a new or improved analytical method might include the following:
• Qualitative identiication of the speciic analytes of interest providing some
structural information to confirm “general behavior” (e.g., retention time,
color change, pH)
• Quantitative determination (at trace levels when necessary) that is accurate,
precise, and reproducible in any laboratory setting when performed accord-
ing to established procedures (e.g., SOPs)
• Stability indicating
• Ease of use
• Ability to be automated
• High sample throughput
• Rapid sample turnaround time
• Low cost per analysis
• Sample preparation that minimizes cost, time, effort, materials, and volume
of sample consumed
• Direct output of qualitative or quantitative data to laboratory computers in
a format usable for evaluation, interpretation, printing, and transmission to
other locations via a network/laboratory information system (LIMS)
Reference standards that have been well identified and characterized, and whose
purity is already known should be used for initial method development and prelimi-
nary evaluation of the goals and requirements of the method, and the initial analyti-
cal performance characteristics for validation should be identified, according to the
type of method/procedure (Chapter 7).
3.4 Hplc metHod development InstrumentAtIon
Since the 1970s, the fundamental components of a basic liquid chromatograph have
consisted of the same basic parts: a pump, a means of injecting a sample, a column,
