Page 126 - Illustrated Pocket Dictionary of Chromatography

METHOD VALIDATION 125

diameter of a particle that can pass through it. Therefore, the number
of meshes in the sieve is inversely proportional to the particle size it
will allow to pass through. Two basic mesh scales are in use: US Stan-
dard and Tyler. Some examples are given below:

US Standard Eq. Particle Diameter (mm)
50 300
80 180
140 106
270 75
400 38

methanol, methyl alcohol Molecular weight: 32.0; boiling point:
64.7°C; refractive index (20°C): 1.3284; density (20°C): 0.79g/mL;
o
viscosity (20°C): 0.55cP; UV cutoff: 205nm; eluotropic strength (e ):
on alumina—0.95, on silica—0.73; polarity index (P¢): 5.1; Hildebrand
solubility parameter (d): 13.7. Miscible with water. Volatile and flam-
mable. Methanol is a very commonly-used solvent in reversed phase
LC and purge & trap GC.

CH 3 OH
Methanol

method development The formalized process by which a set
of separation criteria are determined such that with a defined set of
parameters the same separation profile is achieved. The process of
method development can be qualitative or quantitative. An effective
method development protocol sets out well-defined success criteria,
for example, minimum resolution between peaks, peak asymmetry
and response factor ranges, minimum column efficiency (N), total
analysis time, linearity, linear range, and reproducibility. The finished
separation is optimized to meet all these criteria.

method validation The process that follows method develop-
ment and sets strict limits on the reproducibility, robustness, and
ruggedness of the method. This validation process often includes mul-
tiple sample preparations within one lab, matrix blank analysis (to
ensure that there is no coeluting peak in the matrix that will interfere
with the analyte of interest), multiple laboratory, analyst, and instru-