This paper reports on novel separation methods developed for the direct determination of 14 C in organic carbon (OC) and elemental carbon (EC), two sub-fractions of total carbon (TC) of atmospheric air particulate matter. Until recently, separation of OC and EC has been performed off-line by manual and time-consuming techniques that relied on the collection of massive CO2fractions. We present here two on-line hyphenated techniques between a Sunset OC/EC analyzer and a MICADAS (MIni radioCArbon DAting System) accelerator mass spectrometer (AMS) equipped with a gas ion source. The first implementation facilitates the direct measurement in the low sample size range (<10 μg C) with high throughput on a routine basis, while the second explores the potential for a continuous-flow real-time CO2 gas feed into the ion source. The performance achieved with reference materials and real atmospheric samples will be discussed to draw conclusions on the improvement offered in the field of 14 C aerosol source apportionment.
Letter to the Editor Phosphatidylethanols (PEths) are a group of abnormal phospholipids that can serve as direct alcohol biomarkers. They are formed within the human body from phosphatidylcholines upon enzymatic catalysis by phospholipase D, by exchange of the choline group against ethanol, when alcohol is present. The use of PEths as alcohol biomarker became popular, as they accumulate in red blood cells (RBC), prolonging the window of detection up to several weeks. 1 This can be advantageous for abstinence monitoring when compared with ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine. 2 Currently,
Direct and indirect biomarkers are widely applied for the determination of alcohol consumption. They help to assess past or present alcohol consumption. Depending on the window of detection and sensitivity of the investigated marker, punctual alcohol consumption may remain undetected. In this study, different sampling strategies for the intermediary long‐term marker phosphatidylethanol (PEth) are evaluated and compared to the determination of the short‐term markers ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine. Samples from 19 patients undergoing alcohol use disorder treatment were collected during the withdrawal treatment and successive rehabilitation (33 ± 26 days (range: 3–74 days)). With liquid chromatography–tandem mass spectrometry (LC–MS/MS) EtG and EtS in urine, PEth in blood, PEth in dried blood spot (DBS) from venous blood, and PEth in DBS from capillary blood were quantified and compared. The use of volumetric capillary DBS, prepared from 20 μL of blood, provided the same results as the use of venous DBS (95% ± 10%, R2 0.9899 for PEth 16:0/18:1). Capillary DBS sampling has the advantage that it can be performed without venipuncture. The use of PEth in DBS proved to prevent post‐sampling degradation, providing a longer detection in comparison to PEth in liquid blood, which only showed 67% ± 24% of the PEth DBS 16:0/18:1 concentration. When compared with EtG and EtS in urine, PEth monitoring proved to be advantageous for the detection of relapse situations, as the accumulation of PEth in blood prolongs the detectability. In conclusion, volumetric capillary DBS sampling for PEth is a simple and useful tool for compliance monitoring, and avoids hematocrit issues.
The direct alcohol marker ethyl glucuronide (EtG) is widely used for the assessment of alcohol consumption behavior and abstinence monitoring by hair analysis. We investigated the influence of chlorinated swimming pool water on EtG concentrations in hair in comparison to deionized water (Milli-Q) containing no chlorine. EtG concentrations were measured with a validated online solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method. EtG positive hair samples were obtained from 3 regular drinkers and incubated for 0, 2, 4, 6, 8, and 10 hours at room temperature. EtG concentrations in hair were reduced after 2 hours of incubation in chlorinated water by 20 ± 12% (range: 4-33%), in deionized water by 24 ± 5% (range: 18-29%). Incubation for 10 hours resulted in a decrease in EtG concentrations of 57 ± 6% (range: 52-65%) for chlorinated water and 47 ± 11% (range: 32-60%) for deionized water. To demonstrate washout in forensic hair samples, 20 samples from subjects with known alcohol consumption behavior were investigated additionally. The samples were divided into 2 strands and analyzed with incubation in chlorinated water for 10 hours and for comparison without any incubation. A mean decrease of 53 ± 18% (range: 26-88%) was observed. These results clearly demonstrate that washout effects are caused by water and have a significant impact on EtG concentrations in hair. For people with hair that are regularly exposed to water for a longer period (eg. swimmers), washout effects may lead to a significant decrease of EtG concentrations in hair. Concentrations may fall below threshold concentrations used for the interpretation of consumption habits (7 pg/mg for social consumption, 30 pg/mg for excessive consumption).
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