Organic Geochemistry 171 (2022) 104471 Contents lists available at ScienceDirect Organic Geochemistry journal homepage: www.elsevier.com/locate/orggeochem Fast quantitative analysis of n-alkanes, PAHs and alkenones in sediments M. Raja a, 1, J. Villanueva a, *, C. Moreu-Romero a, M. Giaime a, A. Rosell-Melé a, b, † a Institut de Ciència i Tecnologia Ambientals (ICTA-UAB), Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain b Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain A R T I C L E I N F O A B S T R A C T Associate Editor–Elizabeth Minor The study of different organic biomarker classes is essential to elucidate global Earth dynamics since different biogeochemical processes play a role in regulating environmental and climatic conditions. However, multiproxy Keywords: analysis generally consists of labor-intensive and time-consuming methodologies, which hamper the study of a Selective Pressurized Liquid Extraction large number of samples. Here, we develop and validate a fast analytical method to quantify different classes of Biomarkers organic biomarkers (PAHs, n-alkanes and alkenones) in sediments. This new method sequentally extracts and GC–MS fractionates the target compounds using a pressure liquid extraction (PLE) system, which allows us to selectively PAH Alkenones obtain the analytes by reducing the time of analysis, sample handling and solvent usage. We show that our Paleoclimate method provides reproducible results and high recoveries (>70%), and can be applied to a wide range of Alkanes sedimentary environments, such as oceanic basins, continental slope and shelf, and lakes. Moreover, the method provides reproducible estimates of paleoclimatic indices, such as the carbon preference index (CPI), the average chain length (ACL) and the UK’ 37 -derived sea-surface temperature (SST). Therefore, this new method enables fast quantitative multiproxy analysis of oceanic, coastal and lake sediments. 1. Introduction extraction using organic solvents. The extraction is undertaken using either a Soxhlet apparatus, ultrasonic bath, microwave or PLE system. Sedimentary organic biomarkers are commonly studied in environ­ The resulting extracts require a clean-up or fractionation process using mental and geological sciences as they provide valuable information on column chromatography packed with silica or alumina stationary pha­ Earth system dynamics (Jaeschke et al., 2017; Luo et al., 2019; Fran­ ses, before instrumental analysis. Detection and quantification are cescangeli et al., 2020; López-Quirós et al., 2021). A range of compounds commonly performed by gas chromatography (GC) and GC coupled to can potentially be analysed in the same unit of sediment to provide mass spectrometry (GC–MS). Consequently, conventional methodolo­ complementary information as environmental or climate proxies. This gies to analyse biomarker proxies are labor intensive, time consuming, facilitates undertaking a paleo-multiproxy analysis, which is essential to and require high organic solvent usage. elucidate and understand natural complex processes. However, it is PLE applies solvents at high pressure and temperature to efficiently common to find in the literature studies that are focused only on a few extract analytes from the sample matrix. Selective pressurized liquid classes of compounds, such as n-alkanes, alkenones or PAHs (Bolton extraction (SPLE) combines extraction and clean-up in one step by et al., 2010; Sarma et al., 2017; Martins et al., 2021; Synnott et al., incorporating adsorbents within the extraction cell (Runnqvist et al., 2021), rather than a wider range of available biomarker proxies. 2010; Subedi et al., 2015). Under optimised conditions, the adsorbent Arguably this is due to the need to generate data from a large number of selectively retains a fraction of matrix compounds while releasing the samples and thus applying relatively simple methodologies. target analytes. Therefore, SPLE can produce extracts that do not require Typically, the methodology to analyse different classes of biomarker post-extraction purification procedures before instrumental analysis. proxies requires several procedural steps to address the different po­ SPLE has the potential to reduce sample handling and solvent con­ larities of the target compounds (Jaeschke et al., 2017; Francescangeli sumption and can significantly increase laboratory productivity. There et al., 2020; Bícego et al., 2021). Analyses begin with sediment is a wealth of published SPLE methods designed to quantify chemicals at * Corresponding author. E-mail address: juan.villanueva@uab.cat (J. Villanueva). 1 Present address: Business Partnership Unit, GSK Centre for Sustainable Chemistry, Triumph Road, Nottingham, UK. † Prof, Antoni Rosell-Melé passed away in December, 2021. https://doi.org/10.1016/j.orggeochem.2022.104471 Received 8 February 2022; Received in revised form 19 July 2022; Accepted 19 July 2022 Available online 25 July 2022 0146-6380/© 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). M. Raja et al. Organic Geochemistry 171 (2022) 104471 trace levels (pesticides, organohalide compounds, pharmaceuticals) in (9.5 ◦ C) and high mean precipitation (1500 mm), which drives to a sub- environmental and biological samples, and thorough reviews on PLE Mediterranean vegetation (i.e. a mix of deciduous and sclerophyll spe­ and SPLE methodologies are available (Runnqvist et al., 2010; Subedi cies) (Ninyerola et al., 2005). The Hula valley is located in northern et al., 2015; Alvarez-Rivera et al., 2020). In this study, we describe the Israel. It is a 25 km long and 6–8 km wide valley at approximatively 70 development and validation of an SPLE method to simultaneously m mean above sea level. It was occupied by a lake and marshes; the quantify different biomarker classes in marine and lacustrine sediments. relative extent of each depending on climate and local hydrology. HUL We have focused our study on PAHs, n-alkanes and alkenones that have lake, occupying the south of the valley was artificially dried in the different polarities and yield complementary information as proxies. As 1950s. The region is characterized by high mean temperature (18 ◦ C) part of the method validation, we evaluated its robustness to changes in and low mean precipitation (653 mm). the sedimentary matrix by repeatedly analysing a set of sediments from different depositional environments (open ocean, coastal and 3. Method description lacustrine). The analytical method described below corresponds to the final 2. Materials and samples conditions used to test the analytical robustness. The conditions used for method development are discussed in the Results and discussion section. 2.1. Solvents, reagents and standards Samples were freeze-dried and then homogenised with a Mixer Mill MM 400 (Retsch). PLE and clean-up were performed using an ASE-350 Methanol (MeOH), dichloromethane (DCM), n-hexane (Hex), (Dionex Thermo) equipped with 10 mL extraction cells and 60 mL acetone (Ac) and toluene were of GC analysis grade and purchased from collection vials. We used activated silica as the stationary phase, and Merck KGaA. Silica gel 60 for flash chromatography (0.04–0.06 mm, anhydrous Na2SO4 to remove water and filter residual particles. Thus, 230–400 mesh ASTM) was obtained from Scharlau, anhydrous Na2SO4 extraction cells were filled from bottom to top with a glass fibre filter, 3 g (99.5%) from VWR, and diatomaceous earth for ASE from Thermo Sci­ of activated silica, 1 g of anhydrous Na2SO4, 1–3 g of sediment, and entific. Prior to extraction, silica gel and anhydrous Na2SO4 were diatomaceous earth to completely fill the cell (Fig. 1). On the top of the maintained during 24 h at 105 ◦ C and cooled in a desiccator. cell, 100 µL of an internal standard mixture was added for quantifica­ N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trime­ tion. The composition of the internal standard mixture was hexa­ thylsilyl (TMS) from Thermo Scientific was used to derivatize polar triacontane (C36, 5 ng µL− 1), eicosane (C20, 5 ng µL− 1), 2-nonadecanone compounds (n-alcohols and sterols). Standards of PAHs (D12-perylene (5 ng µL− 1), D12-perylene (0.2 ng µL− 1) and D10-pyrene (0.2 ng µL− 1). and D10-pyrene) were obtained from Supelco and Isotec, respectively. n- Blank samples were prepared similarly to sediment samples, but no Alkane standards (hexatriacontane and eicosane) were purchased from sediment was packed in the cell. Aldrich, and a ketone standard (2-nonadecanone) from Fluka. Standards Samples were extracted at 100 ◦ C with hexane:dichloromethane of n-alcohol (1-heneicosanol) and sterol (5α-androstanol-3β-ol) were (Hex:DCM) (4:3, v/v) using solvent saver mode for 10 min at 2 mL obtained from TCI and Sigma, respectively. min− 1. This step renews the solvent mixture continuously during the extraction, at a controlled flow rate. This is different from the commonly used batch mode that executes several cycles of fill and release of sol­ 2.2. Samples vents. This new mode can improve the capability of silica to retain compounds and also the efficacy of the clean-up process. Continuous Sediment samples used to develop and validate the analytical renewal of solvents may also optimise extraction recovery. The resulting method are listed in Table 1. Marine samples were retrieved in cruises extracts were concentrated under a nitrogen stream at 30 ◦ C using EN651 (northern Tropical Atlantic) and MERS (Catalan Sea, Western TurboVap System (Biotage) and transferred to vials with DCM. Extracts Mediterranean). Lacustrine samples were obtained from Spanish lakes were derivatized with 50 µL of BSTFA and 50 µL of DCM at 70 ◦ C during Lucenza (LUC) (Quiroga, Lugo) and Pedro Muñoz (PEM) (Mota del 1 h prior to instrumental analysis. Derivatized extracts were evaporated Cuervo, Cuenca), and Lake Hula from Israel (HUL). using a centrifugal evaporator (miVac) coupled to a cold trap (Genevac) Deep ocean samples EN651-ST04 and EN651-ST13 were obtained in and redissolved in 20 µL of toluene with 5% BSTFA. the occidental and oriental basins of the northern tropical Atlantic For the quantification of n-alkanes and PAHs, the extracts were Ocean, respectively, far from the direct influence of the continents. Marine coastal sediment MERS-ST10 was retrieved at 70 m from the continental shelf, close to the Spanish coast, whereas MERS-ST7 corre­ sponds to the continental slope, and was obtained near the location of ST10. PEM lake is located in the southeast of the Iberian Peninsula and the relatively high mean temperature (14 ◦ C) and low mean precipitation (417 mm) of that region leads to a Mediterranean vegetation (mainly sclerophyll species). In contrast, LUC lake is located in the northeast of the Peninsula. This region presents relatively low mean temperature Table 1 Location of samples and type of sediment. Sample Type of sediment Latitude Longitude Water depth (m) EN651-ST04 Oceanic 5.00 –35.79 3993 EN651-ST13 Oceanic 10.36 –20.99 5130 MERS-ST7 Coastal 40.07 1.53 1476 MERS-ST10 Coastal 40.30 0.80 70 PEM Lake 39.39 –2.88 – LUC Lake 42.59 –7.11 – HUL Lake 33.08 35.61 – Fig. 1. Pressurized liquid extraction (PLE) packed cell. 2 M. Raja et al. Organic Geochemistry 171 (2022) 104471 analysed using a GC–MS system (Agilent Technologies 5975C) equipped retention capacity (Lundstedt et al., 2006; Osman and Saim, 2012; with a DB-5 ms (30 m × 0.25 mm, 0.25 µm stationary phase). The GC Subedi et al., 2015). Hence, we assumed that silica gel is the optimum carrier gas was helium at a flow of 1.5 mL min− 1. The injection was adsorbent to selectively extract compounds of interest and we focused performed in split-less mode (50 s) at 310 ◦ C. The oven temperature on the optimisation of the remaining parameters. program was as follows: 1 min at 70 ◦ C followed by a gradient of 15 ◦ C min− 1 to 160 ◦ C, a second gradient to 310 ◦ C at 6 ◦ C min− 1, and 4.1.1. Selection of SPLE solvent mixture composition isothermal elution at 310 ◦ C during 15 min. MS acquisition was per­ Several solvent combinations were tested to maximize analyte re­ formed in single ion monitoring (SIM) mode to improve sensitivity and coveries and minimize recoveries of polar compounds: (a) Hex:DCM, (b) selectivity (Table 2). Quantitation of the different compound classes was Hex:Ac, and (c) DCM:MeOH. For each combination, several mixtures obtained using the peak area ratios between the analyte and its associ­ with variable proportions of the polar solvent component (DCM, Ac, and ated internal standard as detailed in Table 2. MeOH) were studied. The remaining experimental parameters were The quantitation of total C37 alkenones and the measurement of the maintained constant (extraction temperature of 100 ◦ C, extraction in alkenone unsaturation ratio UK’ 37 was performed using a GC-FID system solvent saver mode at 1 mL min− 1 during 10 min). Extraction tests were equipped with a capillary column HP-1 (60 m × 0.25 mm, 0.25 µm performed with both spiked blanks and marine sediment MERS-ST7. stationary phase) and 3 mL min− 1 of hydrogen as carrier gas. The Extraction cells were replenished with diatomaceous sand to minimize temperature gradient used to separate the alkenones consisted of a dead volume when needed. multistep gradient: initial temperature at 80 ◦ C during 1 min, gradient to Recoveries of spiked blank samples provided information on the 120 ◦ C at 30 ◦ C min− 1and a second ramp to 320 ◦ C at 6 ◦ C min− 1, fol­ retention capacity of silica gel in the absence of a sedimentary matrix. As lowed by an isocratic elution at 320 ◦ C during 21 min. Sample injection detailed in Fig. 2a–c, both n-alkanes and PAHs are not retained by silica was performed at 320 ◦ C with the split closed for 50 s. Quantification of gel when using Hex:DCM and Hex:Ac mixtures. Ketones require low alkenones was performed using hexatriacontane as internal standard. volumes of DCM (29%) or Ac (17%) to elute from the silica gel adsor­ bent. However, DCM:MeOH solvent mixtures provided inadequate and 4. Results and discussion highly irreproducible results (Fig. 2). Severe reproducibility problems were observed at MeOH contents higher than 20%, where recovery of n- 4.1. Method development and optimisation alkanes, ketones and PAHs varied randomly between 0% and 100%. In contrast, polar interfering compounds (Fig. 3a,b) display a different SPLE method development aims at finding the optimum extraction distribution pattern, with higher recoveries with DCM:MeOH and Hex: conditions to achieve quantitative analyte recovery while minimizing Ac solvent mixtures. Hex:DCM mixtures provided erratic (n-alcohols) or matrix interferences in the final extract. In this study, we used long- low (sterols) recoveries. Accordingly, silica gel can partially retain chain n-alcohols and sterols as representative of polar interferences in aliphatic n-alcohols and sterols when using Hex:DCM as elution solvent the sedimentary matrix. The recovery of non-polar analytes (n-alkanes, mixtures. PAHs, alkenones) and the elimination of polar interferences was inves­ Recoveries of spiked samples containing both sediment and silica gel tigated by spiking sediment samples with the following standards: n- provided similar patterns as spiked blank samples (Fig. 2d–f and 3c,d). alkanes (C20, C32, C34, and C36), PAHs (D10-pyrene, D12-perylene and Thus, recoveries higher than 80% for our target compounds were ob­ retene), ketone (2-nonadecanone), n-alcohol (1-heneicosanol), and ste­ tained when using Hex:DCM and Hex:Ac solvent mixtures. Again, the rol (5α-androstan-3β-ol). Accordingly, the criteria to optimise extraction use of polar DCM:MeOH solvent mixtures resulted in generally irre­ conditions were both maximum analyte recovery (n-alkanes, ketones, producible and low recoveries of n-alkanes, PAHs and ketones. In and PAHs) and minimum recovery of interfering polar compounds. We contrast, polar compounds were quantitatively recovered with Hex:Ac have used n-alcohols and sterols as tracers for polar compounds in the and DCM:MeOH solvent mixtures. Quantitation in samples obtained final extract, assuming that the removal of these lipids of medium po­ with a high proportion of MeOH (>30%) was complicated due to the co- larity will ensure an adequate removal of other polar interfering com­ extraction of abundant sedimentary components. Sediment extracts pounds. Recoveries of the analytes of interest were measured in obtained with DCM/MeOH contained abundant components that duplicate to assess the method reproducibility obtained using different affected the GC–MS analysis, resulting in irreproducible and unreliable solvent mixtures. calculated recoveries (Fig. 2). An exception to the general pattern was Optimisation of SPLE conditions in the ASE350 solvent saver mode D12-perylene, which could not be recovered from the sedimentary includes the following parameters: solvent composition, temperature, matrix by any of the tested solvents (dashed lines in Fig. 2). Low re­ solvent flow and extraction time. Several studies have investigated the coveries of D12-perylene were systematically observed in all tested retention capacity of different hydrophilic adsorbents (alumina, Flo­ sediments (data not shown) and could not be related to losses during risil™ and silica gel) and concluded that silica gel has the greatest sample processing (see Fig. 2b). Accordingly, low recoveries are Table 2 MS parameters used in biomarkers quantification. Biomarker class Compound Internal Standard (IS) m/z (IS m/z) n-Alkanes C21–C35 C36 99 (99) PAHs Perylene (Per) D12-perylene 252 (264) Benzo[a]pyrene (BaP) D10-pyrene 252 (212) Benzo[e]pyrene (BeP) Benzo[b]fluoranthene (BbF) Benzo[k]fluoroanthracene (BkF) Pyrene (Pyr) D10-pyrene 202 (212) Fluoranthracene (Flu) Indenopyrene (Ind) D10-pyrene 276 (212) Benzo[g,h,i]perylene (BghiP) Dibenzoanthracene (DBA) D10-pyrene 278 (212) Retene (Ret) D10-pyrene 234 (212) Benz[a]anthracene (BaA) D10-pyrene 228 (212) 3 M. Raja et al. Organic Geochemistry 171 (2022) 104471 Fig. 2. Recoveries of biomarkers in spiked blank (a–c) and sediment (d–f) samples as a function of the extraction solvent composition. The x-axis indicates the percent of modifier used in each test: DCM (blue), acetone (green), and methanol (purple). Results obtained for D12-perylene were different from the other PAH standards and are represented by dotted lines. Experiments were performed in duplicate (see dots). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig. 3. Recoveries of interfering polar compounds in spiked blank (a,b) and sediment (c,d) samples. probably caused by an unusually strong affinity of this compound to the and reproducible recoveries (80–110%) of our target compounds. sedimentary matrix. However, the retention capability of silica gel is not enough to retain Overall, most Hex:DCM and Hex:Ac solvent mixtures provide good interferences (n-alcohols and sterols), when using polar Ac as a modifier 4 M. Raja et al. Organic Geochemistry 171 (2022) 104471 Table 3 Optimisation of SPLE conditions and concentration ratios (CR). Test # Temp. Time Solvent Flow CR CR CR CR CR (◦ C) (min) (mL min¡1) n-Alkanes PAHs Ketones n-Alcohols Sterols 1 75 5 1 56 49 36 14 0 2 75 5 2 88 85 67 30 1 3 75 10 1 83 77 48 15 0 4 75 10 2 92 96 93 60 1 5 100 5 1 45 43 14 4 0 6 100 5 2 93 91 56 23 0 7 100 10 1 90 90 59 20 0 8 100 10 2 94 95 92 57 1 9 150 5 1 71 66 20 6 0 10 150 5 2 96 99 85 74 4 11 150 10 1 89 88 55 49 8 12 150 10 2 93 100 97 92 85 13 200 5 1 97 99 89 84 65 14 200 5 2 95 95 79 76 48 15 200 10 1 94 100 93 90 95 16 200 10 2 97 100 99 95 100 (Fig. 3). Therefore, the optimum balance between recoveries of the (>75%) and low CR for interferences (<25%). Our data also show that compounds of interest and retention of interfering polar compounds was increasing time and solvent flow rate enhance the CR of the analytes. established at Hex:DCM (4:3, v/v). These results also indicate that Hence, we selected 100 ◦ C, 10 min and 2 mL min− 1 as the optimum moderately polar components of the sedimentary matrix, such as n-al­ conditions for temperature, time and solvent flow, respectively. These cohols and sterols may be selectively recovered in a second extraction conditions allow us to quantitatively recover all target compounds in the using Hex:Ac mixtures. first fraction and minimize the presence of polar interferences. 4.1.2. Optimisation of SPLE solvent flow rate, temperature and time 4.2. Method validation We performed a set of 16 experiments designed to identify the op­ timum temperature, time, and solvent flow rate to quantitatively extract The analytical procedure was developed to identify quantitative the compounds of interest and minimize the presence of polar com­ changes in the sedimentary biomarker composition, which helps to pounds in the extract (Table 3). For all tests, we extracted the sediments elucidate past environmental changes. In order to measure the capa­ twice. The first fraction was obtained with Hex:DCM (4:3, v/v) to elute bility to detect concentration changes, we measured the analytical non-polar compounds, and the second fraction was obtained with Hex: reproducibility and robustness to quantitate C21–C33 n-alkanes, PAHs, Ac (1:1, v/v) to extract polar compounds. The separation of the five and C37 alkenones. We also studied the reproducibility of some indices compound classes (n-alkanes, PAHs, ketones, n-alcohols and sterols) commonly used to investigate past sedimentary conditions, such as the among the two fractions is expressed by the concentration ratio (CR) alkenone UK’37 - and n-alkane CPI and ACL indices. To this end, we per­ between the first fraction and the total recovery (CR = Fr1/(Fr1 + Fr2) formed six analytical runs on different days, distributed within a time × 100) and is shown in Table 3. Hence, a CR close to 100 is associated period of 3 months to account for temporal changes in the laboratory with high recoveries in the first fraction, whereas a CR close to 0 in­ setup. Moreover, the analytical robustness to changes in the sample dicates high recoveries in the second fraction. Ideally, compounds of matrix was assessed by comparing reproducibility and internal standard interest should be recovered in the first fraction and show high CR recoveries in samples of different sedimentary environments (lacustrine, values, while interfering polar compounds should be eluted in the sec­ coastal marine, and pelagic ocean, see Table 1). The results of the ond fraction and present low CR values. method validation have been summarized in Table 4 and Figs. 4 and 5. Our results show that high temperature (>150 ◦ C) provides high CR Coefficient of variation (CV) of C21–C33 n-alkanes ranged between (>75%) for all compound classes (Table 3), indicating that both polar 3.4% and 12.5%, with higher values in lacustrine sediments and non-polar compounds are eluted in the first fraction. In contrast, (10.6–12.5%) compared to marine and oceanic sediments (3.4–6.5%). lower temperatures generally present high CR for the target compounds Similar analytical uncertainty was obtained irrespective of total C21–C33 Table 4 Summary of data obtained during method validation. Concentration values are expressed in ng/g and sea-surface temperatures in ◦ C. Oceanic sediment (EN651_ST04) Coastal sediment (ST7) Lacustrine sediment (PEM) n-Alkanes PAHs Alkenones s.d. n-Alkanes PAHs Alkenones s.d. n-Alkanes PAHs Alkenones s.d. Sum 1.07 × 103 0.86 39 – 1.04 × 103 126 114 – 1.84 × 103 10.1 2%). Re­ very high amounts of fatty acids and esters that masked n-alkane and coveries in organic-rich sediments dropped to 30–70%, indicating a PAH signals (data not shown). These results prompt the conclusion that reduced performance in samples with high TOC. These samples typically silica gel was unable to retain and fractionate the extracted polar con­ contain high concentrations of polar interfering extractable compounds stituents, producing extracts that were unfit for quantitative analysis. (fatty acids, esters, alcohols, etc.) that can overload the silica gel Therefore, the analytical setup may produce reproducible, but inaccu­ adsorption capacity. These situations typically result in decreased IS rate results when applied to shallow lake sediments with high organic recoveries, indicating incomplete sample extraction and/or purification carbon content (>2%). Reliable analysis of these organic-rich lake (i.e. samples LUC and HUL). Nevertheless, this can be overcome by samples requires method modification that involves extensive clean-up reducing the mass of extracted sediment or by implementing additional processes to achieve successful interference removal and higher post-extraction purification protocols. Therefore, potential biases in the extraction recovery of the analytes. analytical accuracy can be detected by implementing systematic con­ The recovery of D12-perylene was systematically low for all tests trols on the internal standard recovery. Alternatively, systematic performed with sediment samples, irrespective of the extraction condi­ detection of polar compounds, such as fatty acids, in the final extract tions (solvent composition, extraction temperature and extraction time). provides another means to identify defective sample clean-up processes. The fact that blank samples produced good D12-perylene recoveries Both indicators can be used to control the quality of the extraction (Fig. 2b) indicates that perylene losses are not related to irreversible process on a sample-to-sample basis. adsorption to silica nor losses during sample handling. Published analytical procedures that use PLE to extract PAH from sediments do not 6. Conclusions report recoveries of D12-perylene nor quantitate perylene (Martinez et al., 2004; Liguori et al., 2006; Choi et al., 2014; Gauchotte-Lindsay We have developed and validated a fast analytical selective pres­ et al., 2014; Net et al., 2014; Magill et al., 2015). In contrast, good re­ surized liquid extraction (SPLE) method for quantitative analysis of coveries of D12-perylene have been reported for fish and soil samples different organic biomarkers classes, including n-alkanes, PAHs and (Lundstedt et al., 2006; Lund et al., 2009). Accordingly, low perylene alkenones, in sediments. Overall, analytical reproducibility and recov­ ery of the proposed SPLE method is similar to other analytical 7 M. Raja et al. Organic Geochemistry 171 (2022) 104471 technologies, such as Soxhlet, MAE (microwave-assisted extraction), aromatic hydrocarbons in marine sediments. Journal of Chromatography A 1340, 8–14. UAE and SFE. The main advantage of the proposed SPLE method is that Flotron, V., Houessou, J., Bosio, A., Delteil, C., Bermond, A., Camel, V., 2003. Rapid sample handling has been significantly reduced by combining extraction determination of polycyclic aromatic hydrocarbons in sewage sludges using and clean-up processes using a SPLE system. This represents a significant microwave-assisted solvent extraction: Comparison with other extraction methods. reduction in solvent consumption and sample manipulation, with the Journal of Chromatography A 999, 175–184. 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International Journal of Analytical Chemistry 2010, e398381. CRediT authorship contribution statement Li, D., Dong, M., Shim, W.J., Kannan, N., 2007. Application of pressurized fluid extraction technique in the gas chromatography–mass spectrometry determination M. Raja: Writing – original draft, Supervision. J. Villanueva: of sterols from marine sediment samples. Journal of Chromatography A 1160, 64–70. Writing – original draft, Methodology, Supervision. C. Moreu-Romero: Liguori, L., Heggstad, K., Hove, H.T., Julshamn, K., 2006. An automated extraction Investigation. M. Giaime: Investigation. A. Rosell-Melé: Funding approach for isolation of 24 polyaromatic hydrocarbons (PAHs) from various marine acquisition. matrixes. Analytica Chimica Acta 573–574, 181–188. López-Quirós, A., Escutia, C., Etourneau, J., Rodríguez-Tovar, F.J., Roignant, S., Lobo, F. J., Thompson, N., Bijl, P.K., Bohoyo, F., Salzmann, U., Evangelinos, D., Declaration of Competing Interest Salabarnada, A., Hoem, F.S., Sicre, M.-A., 2021. Eocene-Oligocene paleoenvironmental changes in the South Orkney microcontinent (Antarctica) linked to the opening of Powell Basin. Global and Planetary Change 204, 103581. The authors declare that they have no known competing financial Lund, M., Duedahl-Olesen, L., Christensen, J.H., 2009. Extraction of polycyclic aromatic interests or personal relationships that could have appeared to influence hydrocarbons from smoked fish using pressurized liquid extraction with integrated fat removal. Talanta 79, 10–15. the work reported in this paper. Lundstedt, S., Haglund, P., Öberg, L., 2006. Simultaneous extraction and fractionation of polycyclic aromatic hydrocarbons and their oxygenated derivatives in soil using Acknowledgments selective pressurized liquid extraction. Analytical Chemistry 78, 2993–3000. Luo, G., Yang, H., Algeo, T.J., Hallmann, C., Xie, S., 2019. Lipid biomarkers for the reconstruction of deep-time environmental conditions. Earth-Science Reviews 189, This manuscript is dedicated to the memory of our friend Antoni 99–124. Rosell-Melé. We thank P. Rivas and N. Penalva for their contribution in Magill, C.R., Denis, E.H., Freeman, K.H., 2015. Rapid sequential separation of samples collection. We are in debt to M. Grelaud and P. Ziveri for kindly sedimentary lipid biomarkers via selective accelerated solvent extraction. Organic Geochemistry 88, 29–34. providing samples. This manuscript has benefitted from the comments Martinez, E., Gros, M., Lacorte, S., Barceló, D., 2004. Simplified procedures for the of reviewers Ellen Hopmans and Phil Meyers. This work was supported analysis of polycyclic aromatic hydrocarbons in water, sediments and mussels. by the European Research Council (PALADYN Project #834934) and the Journal of Chromatography A 1047, 181–188. 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