Detection and quantification of fatty acid ethyl esters in meconium by headspace-solid-phase microextraction and gas chromatography–mass spectrometry

Development and validation of a method for the simultaneous analysis of fatty acid ethyl esters, ethyl sulfate and ethyl glucuronide in neonatal meconium: application in two cases of alcohol consumption during pregnancy

Alcohol consumption during pregnancy constitutes one of the leading preventable causes of birth defects and neurodevelopmental disorders in the exposed children. Fatty acid ethyl esters (FAEEs), ethyl glucuronide (EtG) and ethyl sulfate (EtS) have been studied as potential biomarkers of alcohol consumption. However, most analytical approaches proposed for their analysis in meconium samples consist of separated extraction procedures requiring the use of two meconium aliquots, which is costly in terms of both time and materials. Therefore, the aim of this study was to develop and validate a method for the simultaneous extraction of 9 FAEEs, EtG and EtS from one meconium aliquot. The sample was homogenized using methanol, and then FAEEs were extracted with hexane while EtG and EtS were isolated using acetonitrile. Then, extracts were applied to solid-phase extraction columns and analysed by gas chromatography mass spectrometry (FAEEs) and liquid chromatography tandem mass spectrometry (EtG and EtS). Calibration curves were linear with r values greater than 0.99. The LODs ranged from 0.8 to 7.5 ng/g for FAEEs and were 0.2 ng/g and 0.8 ng/g for EtS and EtG, respectively. LOQs ranged from 5 to 25 ng/g for FAEEs and were 1 ng/g and 2.5 ng/g for EtS and EtG, respectively. Accuracies and precisions were between 93.8 and 107% and between 3.5 and 9.7%, respectively. The recovery values ranged from 89.1 to 109%. The method proved to be sensitive, specific, simple and fast and allowed for the reduction of the amount of organic solvent used for extraction compared to other published data while higher recoveries were obtained. The method was used for analysis of meconium samples in two cases of mothers who were consuming alcohol during pregnancy.

A Systematic Review of Solid-Phase Microextraction Applications in the Forensic Context

Since the introduction in 1990, the solid-phase microextraction (SPME) technology has brought significant progress in many fields of forensic sciences due to the versatility of this fast and solventless alternative to conventional extraction techniques. A systematic review about SPME applications in forensic context from January 1995 to June 2018 was carried out according to systematic review guidelines. The majority of the reviewed articles (40/133) aimed to identify drugs (cannabinoids, cocaine, opiates, amphetamines, simultaneous detection of different drugs of abuse, prescribed drugs); 29 of the 133 articles focused on the investigation of fatalities; 28 of the 133 papers used headspace SPME technique for the identification of markers of chronic alcohol abuse. Sixteen papers involved this technique for the isolation of volatile organic compounds for the human odor profile and 20 concerned forensic applications regarding living people. Solid-phase microextraction was preferably employed in the headspace mode and many kinds of fibers were employed, although polydimethylsiloxane was the most adaptable to many forensic realities. Gas chromatography/mass spectrometry was more frequently used, probably for the well-established coupling with SPME. Most of the papers validated their method to harmonize the scientific approaches of procedures development. Good outcomes are reported on biological material collected from living people as well as on cadaveric samples. The results obtained by most of the studies about alcohol biomarkers on scalp hair have been adopted by the "Society of Hair Testing" to demonstrate abstinence over a pre-defined time period and to assess chronic excessive alcohol consumption.

Efficient determination of six fatty acid ethyl ethers in human whole blood by gas chromatography-mass spectrometry

Fatty acid ethyl esters (FAEEs) have been widely studied as specific markers of ethanol intake and mediators of ethanol-induced diseases. In the present study, a simple and rapid gas chromatography-mass spectrometry (GC-MS) method was established for the qualitative and quantitative analysis of six fatty acid ethyl esters (FAEEs), including ethyl myristate, ethyl palmitate, ethyl stearate, ethyl oleate, ethyl linoleate, and ethyl arachidonate, in human whole blood. FAEEs were extracted from 200 μL of human whole blood by a modified liquid-liquid extraction, and the hexane layer was injected directly into GC-MS with ethyl heptadecanoate as the internal standard. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 5-50 ng/mL and 15-200 ng/mL, respectively. Linearity ranged up to 10 μg/mL with r² higher than 0.998. Accuracy was in the range of 90.3-109.7%, while intra-day and inter-day precision were 0.7-9.3% and 3.4-12.5%, respectively. This method was then applied to 38 real samples from forensic cases. Differences in the most common FAEEs between Chinese and Western subjects were discussed. The relationship of FAEE concentrations with age and gender was also investigated.

Alternative sampling strategies for the assessment of alcohol intake of living persons

Monitoring of alcohol consumption by living persons takes place in various contexts, amongst which workplace drug testing, driving under the influence of alcohol, driving licence regranting programs, alcohol withdrawal treatment, diagnosis of acute intoxication or fetal alcohol ingestion. The matrices that are mostly used today include blood, breath and urine. The aim of this review is to present alternative sampling strategies that allow monitoring of the alcohol consumption in living subjects. Ethanol itself, indirect (carbohydrate deficient transferrin, CDT%) as well as direct biomarkers (ethyl glucuronide, EtG; ethyl sulphate, EtS; fatty acid ethyl esters, FAEEs and phosphatidylethanol species, PEths) of ethanol consumption will be considered. This review covers dried blood spots (CDT%, EtG/EtS, PEths), dried urine spots (EtG/EtS), sweat and skin surface lipids (ethanol, EtG, FAEEs), oral fluid (ethanol, EtG), exhaled breath (PEths), hair (EtG, FAEEs), nail (EtG), meconium (EtG/EtS, FAEEs), umbilical cord and placenta (EtG/EtS and PEth 16:0/18:1). Main results, issues and considerations specific to each matrix are reported. Details about sample preparation and analytical methods are not within the scope of this review.

Analysis of BTEX and chlorinated solvents in meconium by headspace-solid-phase microextraction gas chromatography coupled with mass spectrometry

Meconium is the earliest stool of newborns, and is a complex matrix that reflects the degree of exposure of the fetus to xenobiotics. To investigate fetal exposure to volatile organic compounds, an analytical method was developed to identify and quantify BTEX (benzene, toluene, ethylbenzene, and o,m,p-xylene) and two chlorinated solvents (trichloroethylene and tetrachloroethylene) in meconium. Headspace-solid-phase microextraction coupled with gas chromatography-mass spectrometry was selected because it is simple, sensitive, can be automated, and requires no extensive sample preparation. Several extraction variables were optimized (fiber type, incubation time, temperature of fiber, and use of salt). Because meconium is a complex matrix, quantification by SPME was considered carefully because of potential interference, for example competitive adsorption. Calibration in water was compared with calibration in meconium using external and internal methods (with isotope-labeled compounds). In meconium, limits of quantification were determined to be in the range 0.064-0.096 ng g(-1) for the investigated compounds. All target compounds were determined in "real-case" meconium samples.

Meconium indicators of maternal alcohol abuse during pregnancy and association with patient characteristics

AIM

Identification of women with moderate alcohol abuse during pregnancy is difficult. We correlated self-reported alcohol consumption during pregnancy and patient characteristics with objective alcohol indicators measured in fetal meconium.

METHODS

A total of 557 women singleton births and available psychological tests, obstetric data and meconium samples were included in statistical analysis. Alcohol metabolites (fatty acid ethyl esters (FAEEs) and ethyl glucuronide (EtG)), were determined from meconium and correlated with patient characteristics.

RESULTS

We found that 21.2% of the 557 participants admitted low-to-moderate alcohol consumption during pregnancy. Of the parameters analyzed from meconium, only EtG showed an association with alcohol history (P < 0.01). This association was inverse in cases with EtG value above 120 ng/g. These values indicate women with most severe alcohol consumption, who obviously denied having consumed alcohol during pregnancy. No other associations between socioeconomic or psychological characteristics and the drinking status (via meconium alcohol metabolites) could be found.

CONCLUSION

Women who drink higher doses of ethanol during pregnancy, according to metabolite measures in meconium, might be less likely to admit alcohol consumption. No profile of socioeconomic or psychological characteristics of those women positively tested via meconium could be established.

Ethanol metabolism and its effects on the intestinal epithelial barrier

Ethanol is widely consumed and is associated with an increasing global health burden. Several reviews have addressed the effects of ethanol and its oxidative metabolite, acetaldehyde, on the gastrointestinal (GI) tract, focusing on carcinogenic effects or alcoholic liver disease. However, both the oxidative and the nonoxidative metabolites of ethanol can affect the epithelial barrier of the small and large intestines, thereby contributing to GI and liver diseases. This review outlines the possible mechanisms of ethanol metabolism as well as the effects of ethanol and its metabolites on the intestinal barrier. Limited studies in humans and supporting in vitro data have indicated that ethanol as well as mainly acetaldehyde can increase small intestinal permeability. Limited evidence also points to increased colon permeability following exposure to ethanol or acetaldehyde. In vitro studies have provided several mechanisms for disruption of the epithelial barrier, including activation of different cell-signaling pathways, oxidative stress, and remodeling of the cytoskeleton. Modulation via intestinal microbiota, however, should also be considered. In conclusion, ethanol and its metabolites may act additively or even synergistically in vivo. Therefore, in vivo studies investigating the effects of ethanol and its byproducts on permeability of the small and large intestines are warranted.

Role of microextraction sampling procedures in forensic toxicology

The last two decades have provided analysts with more sensitive technology, enabling scientists from all analytical fields to see what they were not able to see just a few years ago. This increased sensitivity has allowed drug detection at very low concentrations and testing in unconventional samples (e.g., hair, oral fluid and sweat), where despite having low analyte concentrations has also led to a reduction in sample size. Along with this reduction, and as a result of the use of excessive amounts of potentially toxic organic solvents (with the subsequent environmental pollution and costs associated with their proper disposal), there has been a growing tendency to use miniaturized sampling techniques. Those sampling procedures allow reducing organic solvent consumption to a minimum and at the same time provide a rapid, simple and cost-effective approach. In addition, it is possible to get at least some degree of automation when using these techniques, which will enhance sample throughput. Those miniaturized sample preparation techniques may be roughly categorized in solid-phase and liquid-phase microextraction, depending on the nature of the analyte. This paper reviews recently published literature on the use of microextraction sampling procedures, with a special focus on the field of forensic toxicology.

Neonatal screening for prenatal alcohol exposure: assessment of voluntary maternal participation in an open meconium screening program

Meconium fatty acid ethyl esters (FAEEs) are validated biomarkers of fetal alcohol exposure. Meconium FAEE testing can potentially be used as a screen by health-care professionals to identify neonates at-risk for Fetal Alcohol Spectrum Disorder, thereby permitting diagnostic follow-up of these children and early intervention in those who develop disabilities. The purpose of this study was to assess whether women would willingly partake in a screening program of this nature. This was determined by launching a pilot screening program for prenatal alcohol exposure in a high-risk obstetric unit previously shown to have a high prevalence of FAEE-positive meconium via anonymous meconium testing. The program involved voluntary testing of meconium for FAEEs and long-term developmental follow-up of positive cases through an existing public health program. The participation rate in the screening program was significantly lower than when testing was conducted anonymously (78% vs. 95%, respectively; p < 0.05), and the positivity rate was 3% in contrast to 30% observed under anonymous conditions (p < 0.001). These low rates suggest that the majority of mothers who consumed alcohol in pregnancy refused to participate. We conclude that despite the potential benefits of such screening programs, maternal unwillingness to consent, likely due to fear, embarrassment, and guilt, may limit the effectiveness of meconium testing for population-based open screening, highlighting the need for public education and social marketing efforts for such programs to be of benefit.

An improved method for rapidly quantifying fatty acid ethyl esters in meconium suitable for prenatal alcohol screening

Fatty acid ethyl esters (FAEEs) are nonoxidative metabolites of ethanol, and elevated levels of FAEE in meconium are a useful biomarker for heavy prenatal alcohol exposure. FAEE in meconium has been recommended as useful and cost-effective for universal screening for prenatal alcohol exposure. To support an efficient universal screening program, an analytical method to detect and quantify FAEE in meconium needs to be accurate, inexpensive, and rapid. The purpose of this study was to develop an analytical method that would satisfy these criteria and to validate this method using established laboratory guidelines. A method was developed and validated to detect and quantify four FAEEs (ethyl palmitate, ethyl linoleate, ethyl oleate, and ethyl stearate) from 0.5 g of meconium using d(5)-ethyl esters as internal standards. The sample undergoes liquid-liquid extraction with heptane:acetone, the heptane layer is isolated and evaporated, and then, the resulting residue undergoes headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. The detection limits of the four FAEEs ranged from 0.020 to 0.042 nmol/g and are 6- to 25-fold lower than the individual FAEE threshold concentrations (0.5 nmol/g). This method also has good precision with the coefficient of variation ranging from 2.6 to 19.4% for concentrations of individual FAEE between 0.5 and 2.62 nmol/g meconium (n=4). Calculated concentrations of FAEE that underwent extraction from meconium were 100-101% of the expected concentration, demonstrating the accuracy of the method. The peak shape and retention time of each FAEE were unaffected by the presence of the matrix, and there is no carryover at clinically relevant concentrations. This method was also able to produce clean chromatograms from meconium samples that could not be quantified using a previous method because of high chromatographic background. This method provides an optimal approach to detecting and quantifying FAEE in meconium that could be used in a universal screening program for prenatal alcohol exposure.

Rates of fetal alcohol exposure among newborns in a high-risk obstetric unit

Meconium fatty acid ethyl esters (FAEEs) are sensitive and specific biomarkers for prenatal alcohol exposure (PAE) in pregnancy. We recently reported a 2.5% rate of FAEE positive meconium in a general population sample of infants born in the region of Grey-Bruce, Ontario. Women in this region with high-risk pregnancies are transferred to a tertiary care facility in London, Ontario. The objective of this study was to determine, in a population-based sample, whether high-risk pregnancies are associated with an increased risk of in utero alcohol exposure. Grey-Bruce residents transferred to the high-risk obstetric unit of St. Joseph's Health Care in London, Ontario were identified and consented to this anonymous prevalence study. Meconium was collected and analyzed for FAEE using gas chromatography with mass spectrometry. The prevalence of FAEE positive meconium was compared with the population-based prevalence in the Grey-Bruce. Fifty meconium specimens were collected from August 1, 2006 to July 31, 2007. Fifteen (30%) specimens tested positive for FAEE. The results indicate that infants born in the high-risk obstetric unit had a 12-fold higher risk of screening positive for second and third trimester alcohol exposure compared with infants born in the general population of Grey-Bruce (relative risk=12.04, 95% confidence interval=6.40-22.65, P<.0001). These results suggest that the high-risk pregnancies should be screened for PAE and followed-up for potential diagnosis of fetal alcohol spectrum disorder.

Heavy in utero ethanol exposure is associated with the use of other drugs of abuse in a high-risk population

Many ethanol dependent women also use other drugs of abuse that may affect pregnancy outcome and long-term child neurodevelopment. This study investigated the association between drugs of abuse and concurrent use of ethanol in pregnancy. A study cohort of neonates with FAEE levels above 2 nmol per gram meconium, indicative of heavy in utero ethanol exposure, was identified (n=114). Meconium and hair analyses for the presence of other drugs of abuse were obtained for some of these neonates and the rates of drug exposure were compared with the rates in a cohort of neonates who were tested negative (FAEE below 2 nmol per gram meconium) for ethanol exposure (n=622). Odds ratios (ORs) for various drugs were calculated with ethanol exposure. A 15.5% positive rate for intrauterine ethanol exposure was detected. A high rate of in utero drug exposure was detected in neonates with and without in utero ethanol exposure, 60.5% versus 62.7% respectively. Neonates with heavy in utero ethanol exposure were almost twice as likely to be exposed to narcotic opiates (OR=1.90; 95% confidence interval [CI]: 1.13-3.20) and 3.3 times as likely to be exposed to amphetamine (OR=3.30; 95% CI 1.06-10.27) when compared to neonates with no ethanol exposure. Exposure to cannabinoids predicted less likely exposure to ethanol (OR=0.61; 95% CI: 0.38-0.98) and no significant difference was noted in the exposure to cocaine (OR=1.24, 95% CI: 0.81-1.91). Neonates suspected of heavy in utero ethanol exposure should be tested for other drugs of abuse and vice versa. Early detection of drug exposures can facilitate early intervention to both the neonate and the mother, thus decreasing the risk of long-term neurodevelopmental outcomes for the child, including secondary disabilities associated with fetal alcohol spectrum disorder.

Determination of eight fatty acid ethyl esters in meconium samples by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A number of fatty acid ethyl esters (FAEEs) have recently been detected in meconium samples. Several of these FAEEs have been evaluated as possible biomarkers for in utero ethanol exposure. In the present study, a method was optimized and validated for the simultaneous determination of eight FAEEs (ethyl laurate, ethyl myristate, ethyl palmitate, ethyl palmitoleate, ethyl stearate, ethyl oleate, ethyl linoleate and ethyl arachidonate) in meconium samples. FAEEs were extracted by headspace solid-phase microextraction. Analyte detection and quantification were carried out using GC-MS operated in chemical ionization mode. The corresponding D5-ethyl esters were synthesized and used as internal standards. The LOQ and LOD for each analyte were <150 and <100 ng/g, respectively. The method showed good linearity (r(2)>0.98) in the concentration range studied (LOQ-2000 ng/g). The intra- and interday imprecision, given by the RSD of the method, was lower than 15% for all FAEEs studied. The validated method was applied to 63 authentic specimens. FAEEs could be detected in alcohol-exposed newborns (>600 ng/g cumulative concentration). Interestingly, FAEEs could also be detected in some non-exposed newborns, although the concentrations were much lower than those measured in exposed cases.

Opioid detection in maternal and neonatal hair and meconium: characterization of an at-risk population and implications to fetal toxicology

Identification of maternal opioid abuse in pregnancy is often difficult to ascertain in the absence of a reliable self-report. We aimed to characterize an at-risk neonatal population for opioid exposures as well as other drugs of abuse and alcohol. From June 2007 to January 2009, 563 neonatal hair and 1318 meconium specimens were assessed for opioids and were positive in 11.4% and 17.0%, respectively. Neonates testing positive for opioids in hair or meconium analysis were also more likely to test positive for other licit and illicit substances (odds ratiohair, 1.75; 95% confidence interval, 1.03-2.97; odds ratiomeconium, 1.61; 95% confidence interval, 1.16-2.22). Specifically, a positive neonatal hair test for opioids also predicted a positive result for oxycodone. In addition, a positive meconium test result for opioids was associated with positive results for cocaine, oxycodone, methadone, benzodiazepines, and fatty acid ethyl esters (alcohol). Finally, there was a significant correlation between maternal and neonatal hair test results for opioids (Spearman rank rho = 0.657, P = 0.03). Understanding the addiction profiles of these women may lead to better clinical and social management and may largely benefit an at-risk population.

Headspace microextraction: recent bioanalytical applications and issues

Headspace microextraction has already been established as the method of choice for analyzing volatiles blended in complex matrices, such as environmental, food and biological samples. The modern trend of analytical chemistry for ‘going small’ has led to the successful development of various sorbing materials and microextraction techniques. As it is anticipated, microextraction is usually combined with powerful separation and optical techniques permitting enhanced recoveries of analytes, selectivity and sensitivity. In addition, derivatization reactions are often employed for improved detectability of several classes of compounds. Volatile compounds of biological significance are key substances due to the fact that they may constitute a characteristic of the status of the organism. A closer look at the biological applications of the headspace microextraction techniques (solid-phase and single drop microextraction) is the primary aim of this review. The variability of biological samples and analytes are considered primarily, while derivatization and optimization strategies are also discussed.

The evolution of mass spectrometry in the clinical laboratory

Clinical laboratories around the world are recognizing the power of mass spectrometry. This technique, especially when coupled to gas chromatography or liquid chromatography, is revolutionizing the analysis of many analytes. Unlike many other techniques which measure one analyte at a time, these techniques can measure multiple analytes (>40) at one time. In recent years the scope of testing using these techniques has expanded from toxicological purposes to newborn screening to hormones, proteins, and enzymes. It is not uncommon any more to see mass spectrometry being used in the routine clinical laboratories.

Analytical methods used in conjunction with solid-phase microextraction: a review of recent bioanalytical applications

Integration of sampling and sample preparation with various analytical instruments is a highly desirable feature for any analytical method. This is most conveniently achieved by using microextraction techniques or various microdevices. Among these techniques, solid-phase microextraction (SPME) is particularly remarkable due to its simplicity and effectiveness. This review discusses the most recent applications of SPME in bioanalysis, grouped according to the analytical instrument that SPME is coupled to. It is shown that one of the most important aspects of such analytical methods is the ability of SPME to perform direct and selective extraction of analytes from complex biological samples. By far, the most popular method continues to be SPME coupled to GC. Nevertheless, the last 2 years have witnessed significant advances in other areas, such as successful automation of SPME coupled to liquid chromatography and the development of new coatings suitable for direct extraction from biological samples. Furthermore, a few bioanalytical applications based on direct coupling of SPME to MS, ion mobility spectrometry, CE and analytical chemiluminescence have been reported.