Astrid Gjelstad

• Kojen, Aurora Jørnsdatter; Halvorsen, Thomas; Gjelstad, Astrid; Larsen, Stig; Lauritzen, Fredrik & Stensrud, Trine (2026). Reported use of anti-asthmatic medication in doping control forms from 2015 to 2019 – mapping retrospective data. Frontiers in Sports and Active Living. 8. doi: 10.3389/fspor.2026.1815697. Fulltekst i vitenarkiv Vis sammendrag

  Objectives: Asthma and bronchial hyperresponsiveness is common in athletes, particularly in sports with high ventilatory demands or exposure to irritants such as cold, dry air, polluted air, or trichloramines. The mechanisms behind asthma in athletes remain unclear, but repeated high-volume ventilation and exposures to irritants, as well as airway inflammation and remodelling likely contribute. Symptoms resemble those of asthma, and airway hyperresponsiveness plays a key role, even in athletes with no other classic asthma features. Treatment of asthma in athletes follows the same approach as asthma in the general population. Use of asthma medication is commonly reported by athletes on doping control forms (DCFs). Thus, this study aimed to investigate the use of different anti-asthmatic medications among doping-controlled athletes. Methods: This was an observational cross-sectional study, evaluating retrospective data from athletes′ DCFs obtained during 2015–2019 as part of Anti-doping Norway′s national testing program in Norwegian sport, some of whom reappearing in the data set with multiple forms. Results: Of 10 418 DCFs, 1702 (16.3%) contained one or more anti-asthmatic medications. Bronchodilators were most frequently reported, with anticholinergics being most common. DCFs reported from females, national level athletes, and athletes with high risk of asthma contained significantly more anti-asthmatic medications compared to their counterparts (p< 0.01). Usage was highest among athletes aged 30–34, and in those in endurance sports. Conclusion: Despite the limitation of athletes’ reappearance in the dataset, this study provides insight into guideline adherence and asthma medication use among athletes in Norway. Further research is needed in this area.

• Christensen, Sofie; Björnsdottir, Ingunn; Lauritzen, Fredrik & Gjelstad, Astrid (2026). Anti-doping awareness among community pharmacists in Norway: a study using a simulated patient. International Journal of Pharmacy Practice (IJPP). ISSN 0961-7671. 34(2), s. 140–146. doi: 10.1093/ijpp/riaf128. Fulltekst i vitenarkiv
• Gjelstad, Astrid; Holden, Geir; Gundersen, Per Ole Mobråten; Dehnes, Yvette; Tvedte, Magnus & Levernæs, Maren [Vis alle 8 forfattere av denne artikkelen] (2026). Positive Doping Test Linked to Crumb Rubber From Artificial Football Pitch: Case Report. Drug Testing and Analysis. ISSN 1942-7603. doi: 10.1002/dta.70067. Fulltekst i vitenarkiv
• Christensen, Sofie; Gjelstad, Astrid; Björnsdottir, Ingunn & Lauritzen, Fredrik (2024). Medicalization of Sport? A Mixed-Method Study on the Use of Medications in Elite Ice Hockey. Sports. 12(1). doi: 10.3390/sports12010019. Fulltekst i vitenarkiv
• Christensen, Sofie; Gjelstad, Astrid; Björnsdottir, Ingunn & Lauritzen, Fredrik (2024). Motivations for Using Dietary Supplements in Elite Ice Hockey—Controlling Weight and Enhancing Performance. Nutrients. 16(16). doi: 10.3390/nu16162667. Fulltekst i vitenarkiv
• Lorenzo-Parodi, Nerea; Kaziur-Cegla, Wiebke; Gjelstad, Astrid & Schmidt, Torsten C. (2023). Liquid-phase microextraction of aromatic amines: hollow fiber–liquid-phase microextraction and parallel artificial liquid membrane extraction comparison. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 415(9), s. 1765–1776. doi: 10.1007/s00216-023-04579-w. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Aromatic amines (AA) are carcinogenic compounds that can enter the human body through many sources, one of the most important being tobacco smoke. They are excreted with the urine, from which they can be extracted and measured. To that end, hollow fiber-liquid-phase microextraction (HF-LPME) and parallel artificial liquid membrane extraction (PALME) were optimized for the analysis of representative aromatic amines, as alternatives to liquid–liquid extraction (LLE). Relevant extraction parameters, namely organic solvent, extraction time, agitation speed, and acceptor solution pH, were studied, and the two optimized techniques—HF-LPME: dihexyl ether, 45 min, 250 rpm, and pH 1; PALME: undecane, 20 min, 250 rpm and pH 1—were compared. Comparison of the optimized methods showed that significantly higher recoveries could be obtained with PALME than with HF-LPME. Therefore, PALME was further validated. The results were successful for nine different AA, with regression coefficients ( R 2 ) of at least 0.991, limits of detection (LOD) of 45–75 ng/L, and repeatability and peak area relative standard deviations (RSD) below 20%. Furthermore, two urine samples from smokers were measured as proof of concept, and 2-methylaniline was successfully quantified in one of them. These results show that PALME is a great green alternative to LLE. Not only does it use much smaller volumes of toxic organic solvents, and sample—enabling the study of samples with limited available volumes—but it is also less time consuming and labor intensive, and it can be automated. Graphical Abstract

• Gjelstad, Astrid; Herlofsen, Tine Marie; Bjerke, Anne-Linn; Lauritzen, Fredrik & Björnsdottir, Ingunn (2023). Use of pharmaceuticals amongst athletes tested by Anti-Doping Norway in a five-year period. Frontiers in Sports and Active Living. 5. doi: 10.3389/fspor.2023.1260806. Fulltekst i vitenarkiv Vis sammendrag

  Introduction The aim of the study was to map the use of pharmaceuticals by Norwegian athletes registered on doping control forms (DCFs) in a five-year period to examine general and some class specific use of pharmaceuticals across sports and athlete levels. Method Anonymous data from DCFs collected in 2015-2019 were manually entered into a database using the Anatomical Therapeutic Chemical (ATC) system for classification of the pharmaceuticals. Variables entered were year of control, gender, age group, athlete level, sport, test type, nationality, and pharmaceuticals (and dietary supplements) used. Results Pain killers in the ATC groups M01 A (Nonsteroidal anti-inflammatory drugs - NSAIDs) and N02 B (other analgesics), and anti-asthmatics in ATC groups R03 A and R03 B were the most frequently used pharmaceuticals. National level athletes reported more use of pharmaceuticals (1.4 ± 1.7 pharmaceuticals per form) than recreational level athletes (0.9 ± 1.2). The highest proportion of DCFs containing information about at least one pharmaceutical were found in speed skating (79.1%), alpine skiing (74.0%), rowing (72.4%) and cross-country skiing (71.7%). Painkillers were most frequently used in muscular endurance sports (30.4% and 21.2 % for M01A and N02 B, respectively) and ball and team sports (17.9% and 17.0%). Use of hypnotics was reported from ice-hockey players and alpine skiers in around 8% of the cases. Coclusion Use of anti-asthmatics was most often reported amongst athletes specially exposed to cold, chemicals and heavy endurance training. Athletes in specialized sports requiring high levels of strength and/or endurance reported a higher use of pharmaceuticals out-of-competition compared to in-competition, while there was no such difference in complex sports, such as team, gymnastic, aiming and combat sports.

• Lauritzen, Fredrik & Gjelstad, Astrid (2023). Trends in dietary supplement use among athletes selected for doping controls. Frontiers in Nutrition. 10. doi: 10.3389/fnut.2023.1143187. Fulltekst i vitenarkiv Vis sammendrag

  Background Dietary supplements (DS) may be beneficial for athletes in certain situations, whereas incorrect or excessive use may impair performance, pose a risk to the athlete's health and cause positive doping tests by containing prohibited substances. To provide athletes with relevant and tailored information on safe supplement use, a better knowledge about DS trends over time and between sport disciplines are needed. Methods This study examines the use of DS among athletes who have participated in doping controls by extracting information derived from 10,418 doping control forms (DCF) collected by Anti-Doping Norway from 2015 to 2019. Results Overall, 51% of the DCFs contained information about at least one DS. National level athletes (NLA) more often reported using DS than recreational athletes (RA) (53 vs. 47%, p &amp;lt; 0.001). Athletes in strength and power (71%), VO2 max endurance (56%) and muscular endurance sports (55%) had the highest proportion of DCFs with information about DS. Medical supplements were the most used supplement category for both genders and across all sports. Dietary supplements with a high risk of containing doping substances were most common among male, RA in strength and power sports. There were small and non-significant year-to-year variations in the prevalence of athletes using DS, while the number of products used concomitantly peaked in 2017 before declining in 2019 (2.30 vs. 2.08, p &amp;lt; 0.01). The use of medical supplements and ergogenic substances increased slightly for both NLA and RA from 2015 to 2019, while the use of all other supplement categories declined. Conclusion Half of the 10,418 DCFs contained information about DS, with variations within the athlete population. DS with high risk of containing prohibited substances were mostly seen in sport disciplines requiring a high degree of specialization in strength/power, including powerlifting and weightlifting, as well as in some team sports, such as cheerleading and american football.

• Bækken, Lasse Vestli; Holden, Geir; Gjelstad, Astrid & Lauritzen, Fredrik (2022). Ten years of collecting hematological athlete biological passport samples—perspectives from a National Anti-doping Organization. Frontiers in Sports and Active Living. 4. doi: 10.3389/fspor.2022.954479. Fulltekst i vitenarkiv Vis sammendrag

  The hematological module of the Athlete Biological Passport (ABP) aims to reveal blood doping indirectly by looking at selected biomarkers of doping over time. For Anti-Doping Organizations (ADOs), the ABP is a vital tool in the fight against doping in sports through improved target testing and analysis, investigations, deterrence, and as indirect evidence for use of prohibited methods or substances. The physiological characteristics of sport disciplines is an important risk factor in the overall risk assessment and when implementing the hematological module. Sharing of experiences with implementing the hematological ABP between ADOs is key to further strengthen and extend its use. In this study, we present 10 years of experience with the hematological ABP program from the perspectives of a National ADO with special attention to sport disciplines' physiological characteristics as a potential risk factor for blood doping. Not surprisingly, most samples were collected in sport disciplines where the aerobic capacity is vital for performance. The study highlights strengths in Anti-Doping Norway's testing program but also areas that could be improved. For example, it was shown that samples were collected both in and out of season in a subset of the data material that included three popular sports in Norway (Cross-Country Skiing, Nordic Combined, and Biathlon), however, from the total data material it was clear that athletes were more likely to be tested out of competition and on certain days of the week and times of the day. The use of doping control officers with a flexible time schedule and testing outside an athlete's 60 min time-slot could help with a more even distribution during the week and day, and thus reduce the predictability of testing. In addition to promoting a discussion on testing strategies, the study can be used as a starting point for other ADOs on how to examine their own testing program.

• Puventhiran, Nithuja; Malterud, Karl Egil; Wangensteen, Helle & Gjelstad, Astrid (2022). Plantebaserte legemidler – er de forbudt i idrett? Norsk Farmaceutisk Tidsskrift (NFT). ISSN 0029-1935. 7, s. 48–50. Fulltekst i vitenarkiv
• Mestad, Ingrid Oksavik; Gjelstad, Astrid; Pedersen-Bjergaard, Stig & Øiestad, Elisabeth Leere (2021). Green and sustainable drug analysis – Combining microsampling and microextraction of drugs of abuse. Sustainable Chemistry and Pharmacy. 24. doi: 10.1016/j.scp.2021.100517. Fulltekst i vitenarkiv Vis sammendrag

  A novel method combining microsampling of whole blood containing drugs of abuse with 96-well liquid solution microextraction (Parallel Artificial Liquid Membrane Extraction, PALME) and analysis by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was evaluated. Different donor solutions, supported liquid membranes and acceptor solutions were tested, and the most promising set-up was validated. The method included common classes of drugs of abuse, such as opioids, amphetamines, cocaine, benzodiazepines and z-hypnotics. Extraction recoveries above 70% were found for 13 of the compounds, while the last four compounds had recoveries of 10–58%. THC was not extracted with the current method. A linear calibration model was found for all drugs but morphine. Limits of quantitation were between 1 and 5 ng/mL and inter-day precision and accuracy was within 20% for all compounds except for morphine and zopiclone that had a CV of 25% at LOQ. All matrix effects were within 78–123%. Samples were stable for 14 days except for zopiclone and zolpidem. With low-cost, high sample throughput, semi-automated miniaturized sample preparation in combination with dried blood microsamples, and an Eco-Scale score of 78, the proposed method fulfills green chemistry principles.

• Ask, Kristine Skoglund; Lid, Marthe; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2019). Liquid-phase microextraction in 96-well plates - calibration and accurate quantification of pharmaceuticals in human plasma samples. Journal of Chromatography A. ISSN 0021-9673. 1602, s. 117–123. doi: 10.1016/j.chroma.2019.06.013. Fulltekst i vitenarkiv
• Vårdal, Linda; Øiestad, Elisabeth Leere; Gjelstad, Astrid; Jensen, Henrik & Pedersen-Bjergaard, Stig (2019). Electromembrane extraction with solvent modification of the acceptor solution: improved mass transfer of drugs of abuse from human plasma. Bioanalysis. ISSN 1757-6180. 11(8), s. 755–771. doi: 10.4155/bio-2018-0308. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2019). Three-phase hollow fiber liquid-phase microextraction and parallel artificial liquid membrane extraction. TrAC. Trends in analytical chemistry. ISSN 0165-9936. 113, s. 25–31. doi: 10.1016/j.trac.2019.01.007. Fulltekst i vitenarkiv
• Olsen, Katharina Norgren; Ask, Kristine Skoglund; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2018). Parallel artificial liquid membrane extraction of psychoactive analytes: a novel approach in therapeutic drug monitoring. Bioanalysis. ISSN 1757-6180. 10(6), s. 385–395. doi: 10.4155/bio-2017-0250. Fulltekst i vitenarkiv
• Ask, Kristine Skoglund; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2018). Dried blood spots and parallel artificial liquid membrane extraction – A simple combination of microsampling and microextraction. Analytica Chimica Acta. ISSN 0003-2670. 1009, s. 56–64. doi: 10.1016/j.aca.2018.01.024. Fulltekst i vitenarkiv
• Rosting, Cecilie; Tran, Elin Vyvy; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2018). Determination of the Low-Abundant Protein Biomarker hCG from Dried Matrix Spots using Immunocapture and Nano Liquid Chromatography Mass Spectrometry. Journal of Chromatography B: Biomedical Sciences and Applications. ISSN 1387-2273. 1077-1078, s. 44–51. doi: 10.1016/j.jchromb.2018.01.016. Fulltekst i vitenarkiv Vis sammendrag

  Using LC-MS/MS for determination of low-abundance protein biomarkers from dried blood spots is challenging due to the combination of low biomarker levels (low pM-level) and small sample volumes (typically <50 μL). In the present paper it is demonstrated that use of state-of-the-art nano liquid chromatography triple quadrupole mass spectrometry in combination with immunoaffinity sample clean-up enable determination of the low abundance biomarker human chorionic gonadotropin (hCG) from four different biological matrices (whole blood, serum, plasma and urine) at its upper reference level (low pM). Detection limits for hCG was determined for all matrices from both commercially available non-soluble DBS sampling material (DMPK-C) and the water-soluble material carboxymethyl cellulose (CMC). The detection limits (S/N = 3) were ranging from 5.0 IU/L (14.5 pM; whole blood) to 10.5 IU/L (30.5 pM; urine) for DMPK-C and from 2.1 IU/L (6.1 pM; urine) to 6.4 IU/L (18.6 pM; plasma) for CMC. A brief evaluation was performed for both sampling materials using serum as matrix resulting in sufficient linearity (r2 ≥ 0.93, range 20–1000 IU/mL (58–2900 pM) for DMPK-C and 10–1000 IU/mL (29–2900 pM) for CMC), repeatability (RSD% = 13–31%) and accuracy (95–106%). To demonstrate the applicability of the method to real samples, a serum sample from a patient previously diagnosed with cancer was also analyzed using both sampling materials. The concentration levels found using the two materials were similar (5280± 595 IU/L (15,312 ± 1726 pM, n = 3) in the DMPK-C spot and 5060 ± 430 IU/L (14,674 ± 1247 pM, n = 3) in the CMC spot). All in all this demonstrated that the tools for determination of low abundance biomarkers at upper reference level from dried matrix spots now is available through a combination of immunoaffinity enrichment and state-of-the-art LC-MS/MS.

• Vårdal, Linda; Wong, Gladys; Øiestad, Åse Marit Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid & Øiestad, Elisabeth Leere (2018). Rapid determination of designer benzodiazepines, benzodiazepines, and Z-hypnotics in whole blood using parallel artificial liquid membrane extraction and UHPLC-MS/MS. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 410(20), s. 4967–4978. doi: 10.1007/s00216-018-1147-y. Fulltekst i vitenarkiv
• Huang, Chuixiu; Shen, Xiantao; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2018). Investigation of alternative supported liquid membranes in electromembrane extraction of basic drugs from human plasma. Journal of Membrane Science. ISSN 0376-7388. 548, s. 176–183. doi: 10.1016/j.memsci.2017.11.001. Fulltekst i vitenarkiv
• Andersen, Ida Kristine Lysgaard; Rosting, Cecilie; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2018). Volumetric absorptive MicroSampling vs. other blood sampling materials in LC-MS-based protein analysis - preliminary investigations. Journal of Pharmaceutical and Biomedical Analysis. ISSN 0731-7085. 156, s. 239–246. doi: 10.1016/j.jpba.2018.04.036. Fulltekst i vitenarkiv Vis sammendrag

  The aim was to evaluate the performance of different microsampling materials in LC–MS-based protein analysis. The evaluated materials were the Volumetric Absorptive MicroSampling (VAMS) device, the pure cellulose sampling material (DMPK-C) and the water-soluble material (carboxymethyl cellulose, CMC), with the main emphasis on VAMS. Six proteins with different physicochemical properties were used as model proteins. A quick and generic sample preparation consisting of extraction/dissolution of the blood spot, tryptic digestion and subsequent matrix precipitation was applied prior to analysis. The recovery from VAMS, compared to DMPK-C, was dependent on the protein analyte: Lower recovery compared to DMPK-C was seen for β-lactoglobulin and myoglobin (74% and 80%, respectively) while higher recovery compared to DMPK-C was seen for cytochrome c and albumin (149% and 197%, respectively). The recovery from CMC was comparable to the recovery from DMPK-C for all proteins except for cytochrome c (76%). Hematocrit bias was evaluated for DMPK-C and VAMS, and the blood hematocrit influenced the protein analysis from both the materials. A preliminary evaluation was performed for VAMS: The correlation coefficient (R2 ≥ 0.983), the accuracy (71–101%) and the precision (RSD ≤ 20%) were determined for blood spiked with the six model proteins.

• Vårdal, Linda; Øiestad, Elisabeth Leere; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2018). Electromembrane extraction of substances with weakly basic properties: A fundamental study with benzodiazepines. Bioanalysis. ISSN 1757-6180. 10(10), s. 769–781. doi: 10.4155/bio-2018-0030. Fulltekst i vitenarkiv
• Gjelstad, Astrid; Andresen, Alf Terje; Dahlgren, Anders; Gundersen, Thomas Erik & Pedersen-Bjergaard, Stig (2017). High-throughput liquid-liquid extraction in 96-well format: Parallel artificial liquid membrane extraction. LC GC Europe. ISSN 1471-6577. 30(1), s. 10–17. Fulltekst i vitenarkiv Vis sammendrag

  Parallel artificial liquid membrane extraction (PALME) is a miniaturized version of liquid–liquid extraction (LLE) and is based on two 96-well plates in a sandwich-like configuration. With a very simple workflow, 96 samples can be processed simultaneously in PALME, providing analyte enrichment, highly efficient sample cleanup, and direct compatibility with liquid chromatography–mass spectrometry (LC–MS). The consumption of hazardous organic solvents is also almost eliminated using PALME as the sample preparation technique. This article summarizes current experiences with PALME, based on work both in a university laboratory and in an analytical services contract laboratory.

• Fernández, Elena; Vårdal, Linda; Vidal, Lorena; Canals, Antonio; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2017). Complexation-mediated electromembrane extraction of highly polar basic drugs – a fundamental study with catecholamines in urine as model system. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 409, s. 4215–4223. doi: 10.1007/s00216-017-0370-2. Fulltekst i vitenarkiv
• Rosting, Cecilie; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2017). Expanding the knowledge on dried blood spots and LC-MS-based protein analysis: two different sampling materials and six protein targets. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 409(13), s. 3383–3392. doi: 10.1007/s00216-017-0280-3. Fulltekst i vitenarkiv
• Huang, Chuixiu; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2017). Electromembrane extraction with alkylated phosphites and phosphates as supported liquid membranes. Journal of Membrane Science. ISSN 0376-7388. 526, s. 18–24. doi: 10.1016/j.memsci.2016.11.049. Fulltekst i vitenarkiv
• Huang, Chuixiu; Chen, Zhiliang; Gjelstad, Astrid; Pedersen-Bjergaard, Stig & Shen, Xiantao (2017). Electromembrane extraction. TrAC. Trends in analytical chemistry. ISSN 0165-9936. 95, s. 47–56. doi: 10.1016/j.trac.2017.07.027. Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig; Huang, Chuixiu & Gjelstad, Astrid (2017). Electromembrane extraction – Recent trends and where to go. Journal of Pharmaceutical Analysis. ISSN 2095-1779. 7(3), s. 141–147. doi: 10.1016/j.jpha.2017.04.002. Fulltekst i vitenarkiv Vis sammendrag

  Electromembrane extraction (EME) is an analytical microextraction technique, where charged analytes (such as drug substances) are extracted from an aqueous sample (such as a biological fluid), through a supported liquid membrane (SLM) comprising a water immiscible organic solvent, and into an aqueous acceptor solution. The driving force for the extraction is an electrical potential (dc) applied across the SLM. In this paper, EME is reviewed. First, the principle for EME is explained with focus on extraction of cationic and anionic analytes, and typical performance data are presented. Second, papers published in 2016 are reviewed and discussed with focus on (a) new SLMs, (b) new support materials for the SLM, (c) new sample additives improving extraction, (d) new technical configurations, (e) improved theoretical understanding, and (f) pharmaceutical new applications. Finally, important future research objectives and directions are defined for further development of EME, with the aim of establishing EME in the toolbox of future analytical laboratories.

• Restan, Magnus Saed; Jensen, Henrik; Shen, Xiantao; Huang, Chuixiu; Martinsen, Ørjan Grøttem & Kubáň, Pavel [Vis alle 8 forfattere av denne artikkelen] (2017). Comprehensive study of buffer systems and local pH effects in electromembrane extraction. Analytica Chimica Acta. ISSN 0003-2670. 984, s. 116–123. doi: 10.1016/j.aca.2017.06.049. Fulltekst i vitenarkiv
• Gjelstad, Astrid; Andresen, Alf Terje; Dahlgren, Anders; Gundersen, Thomas Erik & Pedersen-Bjergaard, Stig (2017). High-throughput liquid-liquid extraction in 96-well format: Parallel artificial liquid membrane extraction. LC GC North America. ISSN 1527-5949. 35(3), s. 192–196. Fulltekst i vitenarkiv
• Vårdal, Linda; Gjelstad, Astrid; Huang, Chuixiu; Øiestad, Elisabeth Leere & Pedersen-Bjergaard, Stig (2017). Efficient discrimination and removal of phospholipids during electromembrane extraction from human plasma samples. Bioanalysis. ISSN 1757-6180. 9(8), s. 631–641. doi: 10.4155/bio-2017-0027. Fulltekst i vitenarkiv
• Pilarova, Veronika; Sutani, Mumtaz; Ask, Kristine Skoglund; Novakova, Lucie; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2017). One-step extraction of polar drugs from plasma by parallel artificial liquid membrane extraction. Journal of chromatography. B. ISSN 1570-0232. 1043, s. 25–32. doi: 10.1016/j.jchromb.2016.09.019. Fulltekst i vitenarkiv
• Vårdal, Linda; Askildsen, Hilde- Merete; Gjelstad, Astrid; Øiestad, Elisabeth Leere; Edvardsen, Hilde Marie Erøy & Pedersen-Bjergaard, Stig (2017). Parallel artificial liquid membrane extraction of new psychoactive substances in plasma and whole blood. Journal of chromatography. B. ISSN 1570-0232. 1048, s. 77–84. doi: 10.1016/j.jchromb.2017.02.010. Fulltekst i vitenarkiv
• Huang, Chuixiu; Jensen, Henrik; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Mass transfer in electromembrane extraction - The link between theory and experiments. Journal of Separation Science. ISSN 1615-9306. 39(1), s. 188–197. doi: 10.1002/jssc.201500905. Fulltekst i vitenarkiv
• Ask, Kristine Skoglund; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2016). Dried blood spots on carboxymethyl cellulose sheets: Rapid sample preparation based on dissolution and precipitation. Chromatographia. ISSN 0009-5893. 79, s. 509–514. doi: 10.1007/s10337-016-3039-7. Fulltekst i vitenarkiv
• Rosting, Cecilie; Sæ, Christine Østvik; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2016). Evaluation of water-soluble DBS for small proteins: A conceptual study using insulin as a model analyte. Bioanalysis. ISSN 1757-6180. 8(10), s. 1051–1065. doi: 10.4155/bio-2016-0002. Fulltekst i vitenarkiv
• Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Electromembrane extraction of polar basic drugs from plasma with pure bis(2-ethylhexyl) phosphite as supported liquid membrane. Analytica Chimica Acta. ISSN 0003-2670. 934, s. 80–87. doi: 10.1016/j.aca.2016.06.002. Fulltekst i vitenarkiv
• Øiestad, Elisabeth Leere; Øiestad, Åse Marit Leere; Gjelstad, Astrid & Karinen, Ritva Anneli (2016). Oral fluid drug analysis in the age of new psychoactive substances. Bioanalysis. ISSN 1757-6180. 8(7), s. 691–710. doi: 10.4155/bio-2015-0027. Fulltekst i vitenarkiv Vis sammendrag

  Oral fluid has become an important matrix for drugs of abuse analysis. These days the applicability is challenged by the fact that an increasing number of new psychoactive drugs are coming on the market. Synthetic cannabinoids and synthetic cathinones have been the main drug classes, but the diversity is increasing and other drugs like piperazines, phenethylamines, tryptamines, designer opioids and designer benzodiazepines are becoming more prevalent. Many of the substances are very potent, and low doses ingested will lead to low concentrations in biological media, including oral fluid. This review will highlight the phenomenon of new psychoactive substances and review methods for oral fluid drug testing analysis using on-site tests, immunoassays and chromatographic methods.

• Huang, Chuixiu; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Organic solvents in electromembrane extraction: recent insights. Analitical chemistry (Tel Aviv, 1993). ISSN 0793-0135. 35(4), s. 169–183. doi: 10.1515/revac-2016-0008. Fulltekst i vitenarkiv
• Ask, Kristine Skoglund; Turgay, Bardakci; Parmer, Marthe Petrine; Halvorsen, Trine Grønhaug; Øiestad, Elisabeth Leere & Pedersen-Bjergaard, Stig [Vis alle 7 forfattere av denne artikkelen] (2016). Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma. Journal of Pharmaceutical and Biomedical Analysis. ISSN 0731-7085. 129, s. 229–236. doi: 10.1016/j.jpba.2016.07.011. Fulltekst i vitenarkiv
• Kuban, Pavel; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Micro-electromembrane extraction using multiple free liquid membranes and acceptor solutions – Towards selective extractions of analytes based on their acid-base strength. Analytica Chimica Acta. ISSN 0003-2670. 943, s. 64–73. doi: 10.1016/j.aca.2016.09.022. Fulltekst i vitenarkiv
• Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2015). Electromembrane extraction for pharmaceutical and biomedical analysis - Quo vadis. Journal of Pharmaceutical and Biomedical Analysis. ISSN 0731-7085. 113, s. 97–107. doi: 10.1016/j.jpba.2015.01.038. Fulltekst i vitenarkiv
• Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2015). The potential of electromembrane extraction for bioanalytical applications. Bioanalysis. ISSN 1757-6180. 7(4), s. 463–480. doi: 10.4155/bio.14.303. Fulltekst i vitenarkiv
• Gjelstad, Astrid; Pedersen-Bjergaard, Stig & Seip, Knut Fredrik (2015). Electromembrane extraction as a rapid and selective miniaturized sample preparation technique for biological fluids. Bioanalysis. ISSN 1757-6180. 7(17), s. 2203–2209. doi: 10.4155/bio.15.150. Fulltekst i vitenarkiv
• Huang, Chuixiu; Gjelstad, Astrid; Seip, Knut Fredrik; Jensen, Henrik & Pedersen-Bjergaard, Stig (2015). Exhaustive and stable electromembrane extraction of acidic drugs from human plasma. Journal of Chromatography A. ISSN 0021-9673. 1425, s. 81–87. doi: 10.1016/j.chroma.2015.11.052. Fulltekst i vitenarkiv
• Huang, Chuixiu; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2015). Exhaustive extraction of peptides by electromembrane extraction. Analytica Chimica Acta. ISSN 0003-2670. 853(1), s. 328–334. doi: 10.1016/j.aca.2014.10.017. Fulltekst i vitenarkiv
• Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid; Shen, Xiantao & Pedersen-Bjergaard, Stig (2015). Combination of Electromembrane Extraction and Liquid-Phase Microextraction in a Single Step: Simultaneous Group Separation of Acidic and Basic Drugs. Analytical Chemistry. ISSN 0003-2700. 87(13), s. 6951–6957. doi: 10.1021/acs.analchem.5b01610. Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2015). Sample preparation. I Hansen, Steen Honoré & Pedersen-Bjergaard, Stig (Red.), Bioanalysis of pharmaceuticals : sample preparation, separation techniques and mass spectrometry. Wiley-Blackwell. ISSN 9781118716823. s. 73–121. Fulltekst i vitenarkiv
• Roldán-Pijuán, Mercedes; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2015). Parallel artificial liquid membrane extraction of acidic drugs from human plasma. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 407(10), s. 2811–2819. doi: 10.1007/s00216-015-8505-9. Fulltekst i vitenarkiv
• Huang, Chuixiu; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2015). Selective electromembrane extraction based on isoelectric point: Fundamental studies with angiotensin II antipeptide as model analyte. Journal of Membrane Science. ISSN 0376-7388. 481, s. 115–123. doi: 10.1016/j.memsci.2015.02.006. Fulltekst i vitenarkiv
• Rosting, Cecilie; Gjelstad, Astrid & Halvorsen, Trine Grønhaug (2015). Water-Soluble Dried Blood Spot in Protein Analysis: A Proof-of-Concept Study. Analytical Chemistry. ISSN 0003-2700. 87(15), s. 7918–7924. doi: 10.1021/acs.analchem.5b01735. Fulltekst i vitenarkiv
• Seip, Knut Fredrik; Faizi, Moheba; Vergel, Cristina; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Stability and efficiency of supported liquid membranes in electromembrane extraction-a link to solvent properties. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 406(8), s. 2151–2161. doi: 10.1007/s00216-013-7418-8. Fulltekst i vitenarkiv
• Huang, Chuixiu; Eibak, Lars Erik; Gjelstad, Astrid; Shen, Xiantao; Trones, Roger & Jensen, Henrik [Vis alle 7 forfattere av denne artikkelen] (2014). Development of a flat membrane based device for electromembrane extraction: A new approach for exhaustive extraction of basic drugs from human plasma. Journal of Chromatography A. ISSN 0021-9673. 1326, s. 7–12. doi: 10.1016/j.chroma.2013.12.028. Fulltekst i vitenarkiv
• Parmer, Marthe Petrine; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Parallel Artificial Liquid Membrane Extraction (PALME): A new tool for sample preparation. GIT Laboratory Journal Europe. ISSN 1611-6038. 18(11-12), s. 18–19. doi: 10.4155/bio.13.59. Fulltekst i vitenarkiv
• Eibak, Lars Erik; Parmer, Marthe Petrine; Rasmussen, Knut Einar; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2014). Parallel electromembrane extraction in a multiwell plate. Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 406(2), s. 431–440. doi: 10.1007/s00216-013-7345-8. Fulltekst i vitenarkiv
• Seip, Knut Fredrik; Jensen, Henrik; Kieu, Elisabeth Thanh; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Salt effects in electromembrane extraction. Journal of Chromatography A. ISSN 0021-9673. 1347, s. 1–7. doi: 10.1016/j.chroma.2014.04.053. Fulltekst i vitenarkiv
• Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Electromembrane extraction - Three-phase electrophoresis for future preparative applications. Electrophoresis. ISSN 0173-0835. 35(17), s. 2421–2428. doi: 10.1002/elps.201400127. Fulltekst i vitenarkiv
• Eibak, Lars Erik; Rasmussen, Knut Einar; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2014). Parallel electromembrane extraction in the 96-well format. Analytica Chimica Acta. ISSN 0003-2670. 828, s. 46–52. doi: 10.1016/j.aca.2014.04.038. Fulltekst i vitenarkiv
• Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2013). Recent Developments in Electromembrane Extraction. Analytical Methods. ISSN 1759-9660. 5(18), s. 4549–4557. doi: 10.1039/c3ay40547h. Fulltekst i vitenarkiv
• Lødøen, Christine Pernille; Eibak, Lars Erik; Rasmussen, Knut Einar; Pedersen-Bjergaard, Stig; Andersen, Therese & Gjelstad, Astrid (2013). Storage of Oral Fluid as Dried Spots on Alginate and Chitosan foam – A New Concept for Oral Fluid Collection. Bioanalysis. ISSN 1757-6180. 5(3), s. 317–325. doi: 10.4155/BIO.12.315. Fulltekst i vitenarkiv
• Seip, Knut Fredrik; Jensen, Henrik; Hovde, Marit; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2013). Electromembrane extraction: Distribution or electrophoresis? Electrophoresis. ISSN 0173-0835. 34(5), s. 792–799. doi: 10.1002/elps.201200587. Fulltekst i vitenarkiv
• Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2013). Electromembrane extraction from aqueous samples containing polar organic solvents. Journal of Chromatography A. ISSN 0021-9673. 1308, s. 37–44. doi: 10.1016/j.chroma.2013.07.105. Fulltekst i vitenarkiv

Se alle arbeider i NVA

• Christensen, Sofie; Gjelstad, Astrid; Lauritzen, Fredrik & Björnsdottir, Ingunn (2023). Medikalisering av idretten - legemiddelbruk i norsk elite ishockey. Fulltekst i vitenarkiv
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• Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2017). Recent trends in drug analysis using liquid-phase microextraction. Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2017). Microextraction through supported liquid membranes – Tuning the extraction chemistry for biomedical and pharmaceutical applications. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2017). Does Parallel Artificial Liquid Membrane Extraction Match the Requirements for an Applicable and High-Throughput Sample Preparation Method from Biological Matrices? Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig; Gjelstad, Astrid & Rasmussen, Knut Einar (2017). Arrested development – Given ongoing challenges in sample preparation and lack of novel alternatives, is it time to give liquid-phase microextraction (LPME) a second chance? The Analytical Scientist. ISSN 2051-4077. 49, s. 46–49. Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2016). Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma. Fulltekst i vitenarkiv
• Ask, Kristine Skoglund; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2016). Parallel Artificial Liquid Membrane Extraction - En ny metode for fjerning av fosfolipider. Fulltekst i vitenarkiv
• Kuban, Pavel; Boceka, Petr; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Multiple phase micro-electromembrane extraction for selective pretreatment of raw biological samples. Fulltekst i vitenarkiv
• Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2016). Liquid-phase microextraction – recent trends and where to go? Fulltekst i vitenarkiv
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• Gjelstad, Astrid (2016). Microextraction from aqueous samples based on supported liquid membranes - recent trends and new applications. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2016). Parallel Artificial Liquid Membrane Extraction - A New Way to Perform Selective Sample Preparation from Biological Matrices. Fulltekst i vitenarkiv
• Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2016). Parallel Artificial Liquid Membrane Extraction as a Selective, Single-step Sample Preparation Method of Human Plasma Prior to LC-MS. Fulltekst i vitenarkiv
• Ask, Kristine Skoglund; Halvorsen, Trine Grønhaug; Pedersen-Bjergaard, Stig & Gjelstad, Astrid (2015). Phospholipid removal from human plasma samples by Parallel Artificial Liquid Membrane Extraction. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2015). Parallel Artificial Liquid Membrane Extraction – A New Way to Perform Selective Sample Preparation from Biological Matrices. Fulltekst i vitenarkiv
• Vårdal, Linda; Øiestad, Elisabeth Leere; Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2015). Development of Stable, Selective, and Efficient Artificial Liquid Membranes for Electromembrane Extraction (EME). Fulltekst i vitenarkiv
• Huang, Chuixiu; Seip, Knut Fredrik; Gjelstad, Astrid; Shen, Xiantao & Pedersen-Bjergaard, Stig (2015). Combination of electromembrane extraction and liquid-phase microextraction in a single step: simultaneous extraction of acidic drugs and basic drugs. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2015). Parallel Artificial Liquid Membrane Extraction – A New, Selective Sample Preparation Method from Biological Matrices. Fulltekst i vitenarkiv
• Gjelstad, Astrid & Seip, Knut Fredrik (2015). Sample extraction techniques for biological samples: Recent advances and novel applications. Bioanalysis. ISSN 1757-6180. 7(17), s. 2133–2134. doi: 10.4155/bio.15.165. Fulltekst i vitenarkiv
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• Seip, Knut Fredrik; Faizi, Moheba; Vergel, Cristina; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Erratum: Stability and efficiency of supported liquid membranes in electromembrane extraction - A link to solvent properties Microextraction Techniques (Analytical and Bioanalytical Chemistry DOI 10.1007/s00216-013-7418- 8). Analytical and Bioanalytical Chemistry. ISSN 1618-2642. 406(8), s. 2217–2217. doi: 10.1007/s00216-013-7579-5. Fulltekst i vitenarkiv
• Gjelstad, Astrid (2014). Parallel artificial liquid membrane extraction (PALME) - an innovative implementation of liquid-liquid extraction into a multiwell plate. Fulltekst i vitenarkiv
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• Seip, Knut Fredrik; Gjelstad, Astrid & Pedersen-Bjergaard, Stig (2014). Elektromembranekstraksjon - Distribusjon eller elektroforese? Fulltekst i vitenarkiv
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• Eibak, Lars Erik; Pedersen-Bjergaard, Stig; Rasmussen, Knut Einar & Gjelstad, Astrid (2014). Ekstraksjon av legemidler fra plasma, urin og fullblod ved bruk av elektriske felt. Fulltekst i vitenarkiv
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Se alle arbeider i NVA