Accelerated solvent extraction for the evaluation of prenatal exposure to drugs of abuse

Drug abuse is an important and worldwide problem with several health and legal connotations. The intake of these substances during pregnancy is especially critical since it affects both the mother and the growing infant. In this sense, potential effects caused by drug intake include decreased birth weight, body length and head circumference, intra-uterine growth retardation, impairment of normal fetal brain development, placental insufficiency, fetal distress, intra-uterine death, and a higher risk of premature birth.

Despite the importance of this problem, epidemiological studies are scarce due to different reasons. The absence of self-reports owing to the potential negative legal consequences and the social stigma that is attached to admitting drug abuse, are the main causes. In this context, it would be interesting to develop analytical methodologies capable to detect and quantify this in-utero exposure to drugs in order to prevent negative consequences or to enable the obtaining of epidemiological data, depending on whether the analysis is performed during pregnancy or after delivery.

Meconium, which is the earliest stool of a mammalian infant, is specially interesting on the evaluation of in-utero exposure to drugs. It starts forming in weeks 12-13 of gestation and contains metabolites from a potential drug intake. However, meconium is a complex sample (it contains plenty of compounds) and its use can be considered an analytical challenge.

In an article recently published in Journal of Chromatography B, Brazilian researchers have evaluated the potential of accelerated solvent extraction (ASE) for the isolation of biomarkers of cocaine and crack consumption in meconium samples (1). The ASE allows the easy extraction of the target compounds since it is performed at high temperature and pressure. The selected solvent plays a key-role in ASE. In this case, our colleagues used an aqueous phase (phosphate buffer) overheated at 120 ºC. Thanks to the use of high pressures, the aqueous phase remained on its liquid state. According to the authors, in such conditions the aqueous phase has a similar behavior than that observed for organic solvents allowing the extraction of moderate to low polar compounds.

Figure. Chemical structures of cocaine and anhydroecgonine methyl ester (crack marker). These are two of the targets considered in this study

The ASE extract is finally processed by solid phase extraction (using a Bond Elute Certify cartridge) to further improve the selectivity. The final extract is evaporated to dryness and derivatized to make possible the determination of the target analytes by GC/MS. The developed method, which presents limits of detection as low as 11 ng/g, was applied to 342 real samples from a hospital of Sao Paulo.

Reading the optimization of the ASE procedure as well as the analysis of real samples is strongly recommended. We hope you enjoy the original manuscript.

References:

(1) Development and practical application of accelerated solvent extraction for the isolation of cocaine/crack biomarkers in meconium samples. Link to the article