Biomedical Engineering Reference
In-Depth Information
steroid hormones in human plasma [ 32 ] , urine [ 7, 37, 39 ] , and environmental water
[ 34, 45, 78, 79 ]. If both LC-MS/MS and GC-MS/MS methodologies require similar
sample preparation procedures, e.g., deconjugation, extraction, and derivatization,
and they provide the same or comparable sensitivity in steroid hormone analyses,
the choice of an LC-MS/MS or a GC-MS/MS methodology may depend on the
instrument availability and the cost of the testing.
3.2
LC-MS/MS and GC-MS vs. Immunoassays
IA and RIA are broadly used technologies in steroid hormone analyses by both
clinical laboratories and environmental agencies, because they are sensitive, conve-
nient, simple, rapid, and inexpensive. Their disadvantage is lack of selectivity or
speci fi city [ 4, 14, 15 ]. Since selectivity or specificity of bioanalytical methodolo-
gies is essential for clinical diagnosis testing, a number of studies have been con-
ducted to compare LC-MS/MS and GC-MS methodologies with immunoassays in
steroid hormone analysis. A study for determining nine androgens and three estro-
gens in blood showed that LC-MS/MS, GC-MS, and RIA provided similar results,
however, RIA resulted in significant higher values for all related hormones than
LC-MS/MS and GC-MS, due to its cross interferences from analogue compounds
[ 80 ]. Another study also indicated that direct RIA overestimated estrogen sulfate in
plasma than GC-MS and LC-MS/MS [ 65 ]. Similar results were observed in analysis
of estrogens by IA and RIA against LC-MS/MS as well [ 19 ] . All these studies
suggest that LC-MS/MS and GC-MS are more selective or specific and accurate
than RIA. Nevertheless, LC-MS/MS and GC-MS instruments require more sophis-
ticated expertise to perform the bioanalytical testing, and to provide reliable inter-
pretations of the results for clinical diagnoses.
4
Standardization of Analytical Procedures
Development of LC-MS/MS or GC-MS analytical methods is just the first step in
bioanalysis. A number of additional procedures should also be established to make
the whole bioanalytical platform including reference standards, methodologies and
data systems in compliance with scientific and regulatory guidelines or require-
ments. Otherwise, the results from various techniques, e.g., IA, RIA, LC-MS/MS,
and GC-MS, may not be comparable and acceptable for clinical diagnosis. As there
are a large number of scientific publications and clinical applications on steroid
hormone analyses, organizations like the Center for Disease Control and Prevention,
Division of Laboratory Science of National Center for Environmental Health have
attempted to standardize the clinical laboratory practice, analytical methodology
and data management in steroid hormone analyses (CDC/NCEH/DLS, [ 81- 83 ] ).
The National Institute of Standards and Technology (NIST) has made efforts on
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