6.1 Detection and quantification of added drugs
Toxicological analysis aims at controlling prohibited substances
and sometimes may be limited to qualitative analysis; however, it
is often necessary to quantify the active substances in order to
assess the significance of the adulteration for human health.
Reliable risk assessment requires the development and/or application
of an efficient analytical method. The analyst must select
the most appropriate method of analysis among those available.
When adulteration is suspected, the first objective is the
identification of the class of molecules to be searched for. The
chemical nature, as well as the toxicokinetic and toxicodynamic
aspects of the hypothesized agent, must be assessed, since all
these factors affect the analytical procedure, and the laboratory
involved must be suitably equipped and staffed by trained
personnel to allow rapid and valid analyses.
Several analytical approaches have been developed. Screening
is an essential first step, and more than one screening method
must be applied because thousands of chemical substances are
involved. The putative adulterant should be classified according
to its acidic, neutral or alkaline nature and separated with
appropriate solvent systems and reagents. Thin-layer chromatography
(TLC) and its improved version High Performance
TLC (HPTLC) are widely used in screening to detect or exclude
whole classes of substances, and is particularly suitable in
screening for hormones.
More sensitive and specific analytical techniques must be
used to quantify the contaminant, e.g. gas chromatography–
mass spectrometry (GC-MS), high-performance liquid chromatography
(HPLC) plus mass spectrometry (HPLC-MS)
using different ion sources and analyzers, and capillary electrophoresis
(CE).
Knowledge of symptoms can limit the search to a few classes of
compounds, and clinical data and pharmacological activity are
available for some common food supplements, but even when
sophisticated analytical techniques are used, the identification
and quantification of adulterants requires time, expensive
procedures and the availability of purified standards.
6.1 Detection and quantification of added drugsToxicological analysis aims at controlling prohibited substancesand sometimes may be limited to qualitative analysis; however, itis often necessary to quantify the active substances in order toassess the significance of the adulteration for human health.Reliable risk assessment requires the development and/or applicationof an efficient analytical method. The analyst must selectthe most appropriate method of analysis among those available.When adulteration is suspected, the first objective is theidentification of the class of molecules to be searched for. Thechemical nature, as well as the toxicokinetic and toxicodynamicaspects of the hypothesized agent, must be assessed, since allthese factors affect the analytical procedure, and the laboratoryinvolved must be suitably equipped and staffed by trainedpersonnel to allow rapid and valid analyses.Several analytical approaches have been developed. Screeningis an essential first step, and more than one screening methodmust be applied because thousands of chemical substances areinvolved. The putative adulterant should be classified accordingto its acidic, neutral or alkaline nature and separated withappropriate solvent systems and reagents. Thin-layer chromatography(TLC) and its improved version High PerformanceTLC (HPTLC) are widely used in screening to detect or excludewhole classes of substances, and is particularly suitable inscreening for hormones.More sensitive and specific analytical techniques must beused to quantify the contaminant, e.g. gas chromatography–mass spectrometry (GC-MS), high-performance liquid chromatography(HPLC) plus mass spectrometry (HPLC-MS)using different ion sources and analyzers, and capillary electrophoresis(CE).Knowledge of symptoms can limit the search to a few classes ofcompounds, and clinical data and pharmacological activity areavailable for some common food supplements, but even whensophisticated analytical techniques are used, the identificationand quantification of adulterants requires time, expensiveprocedures and the availability of purified standards.
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