Barbiturates quantification

Street (34) developed an "on column" derivative formation technique using N,0-bis (trimethylsilyl) acetamide (BSA). A few microliters of BSA are drawn into a 10-yl syringe followed by several microliters of extract to be chromatographed. The whole is injected onto the column with the resultant formation of and separation of the derivatives. This procedure is recommended for the formation of methyl and trimethylsilyl derivatives in qualitative determinations, and the separation of nonderivatized barbiturates for quantification procedures. 

Quantification of Barbiturates If a 5,5-substituted barbiturate is present, the approximate concentration ing/ml) in the original sample can be calculated in two ways ... 

Quantification. The following are general methods for most barbiturates. 

To understand the identification and quantification techniques used to analyse barbiturates and benzodiazepines. 

In some cases, the forensic scientist will be required to quantify barbiturates and benzodiazepines in drug samples. Due to the problems associated with sample derivatization, quantification of barbiturates can best be achieved by using HPLC. Benzodiazepines are thermally labile compounds and thus HPLC is again the method of choice for qualitative analysis. 

Quantification of barbiturates in thus achieved in the usual way by employing this approach. 

The basic principles behind the quantification of benzodiazepines are the same as those applicable to barbiturates. A typical set of HPLC operating conditions used for such analyses are shown in Table 9.5. Again, the compounds elute in order of increasing lipophilicity and, owing to the lack of any good chromophoric groups (cf. the barbiturates), a UV detection wavelength of 240 nm is also used for such materials. 

Cais, who coined the term metalloimmunoassay, prepared a series of organometallic markers (metallohaptens) with the potential for use in immunoassay. These are derivatives of steroids (estradiol, estriol), mood-altering drugs (amphetamine and cocaine) or medications (morphine and barbiturates), labeled with ferrocene, cobaltocenium and cymantrene [57-59]. He then assessed the use of a Sepharose 4B column to separate the free and bound fractions of the tracer and quantification of the tracer by atomic absorption spectrometry [58]. 

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