{"doi":"10.1177/000456328602300410","title":"A Rapid HPLC Method for Monitoring Plasma Levels of Caffeine and Theophylline Using Solid Phase Extraction Columns","abstract":"<jats:p>\n                    A simple HPLC method for the determination of caffeine and theophylline in plasma is described. Separation of theobromine, paraxanthine, theophylline, β-hydroxyethyltheophylline and caffeine is obtained using a mobile phase of 1% acetic acid/methanol (83:17, v/v) and a Waters Associates NOVA-PAK C\n                    <jats:sub>18</jats:sub>\n                    column protected by a Guard-PAK precolumn module containing a Guard-PAK CN cartridge. Rapid sample preparation is achieved by solid-phase extraction columns (Bond-Elut C\n                    <jats:sub>18</jats:sub>\n                    , 1 mL capacity) which provide excellent recovery values for both drugs. The cost per sample using this approach can be minimised by column regeneration and re-use. Results obtained for theophylline are in good agreement with values determined by other techniques.\n                  </jats:p>","journal":"Annals of Clinical Biochemistry: International Journal of Laboratory Medicine","year":1986,"id":26826,"datarank":3.119541531253296,"base_score":3.6888794541139363,"endowment":3.6888794541139363,"self_citation_contribution":0.5533319181170905,"citation_network_contribution":2.5662096131362055,"self_endowment_contribution":0.5533319181170905,"citer_contribution":2.5662096131362055,"corpus_percentile":null,"corpus_rank":null,"citation_count":39,"citer_count":39,"citers_with_citation_signal":31,"citers_with_endowment":31,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":154297,"name":"A D Stewart","orcid":null,"position":1,"is_corresponding":false},{"id":154298,"name":"R Hartley","orcid":null,"position":2,"is_corresponding":false},{"id":154299,"name":"M D Lucock","orcid":null,"position":3,"is_corresponding":false},{"id":154296,"name":"Clare E Pickard","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":3.6888794541139363,"endowment":3.6888794541139363,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"3532920","pmcid":null,"openalex_id":"https://openalex.org/W2170494490","authors":[],"funders":[],"total_grants":0,"fwci":0.5779,"citation_percentile":0.63545185,"influential_citations":0,"citation_trend":[{"year":2013,"count":1},{"year":2014,"count":1},{"year":2016,"count":1},{"year":2018,"count":1},{"year":2021,"count":1},{"year":2023,"count":1},{"year":2025,"count":1}],"oa_status":"closed","license":"https://journals.sagepub.com/page/policies/text-and-data-mining-license","oa_locations":[{"url":"http://journals.sagepub.com/doi/pdf/10.1177/000456328602300410","host_type":"BRONZE"},{"url":"https://journals.sagepub.com/doi/pdf/10.1177/000456328602300410","host_type":"publisher"},{"url":"https://doi.org/10.1177/000456328602300410","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/3532920","host_type":"repository"}],"fields_of_study":["Analytical Chemistry and Chromatography","Analytical Methods in Pharmaceuticals","Electrochemical sensors and biosensors","Chemistry","Medicine","Caffeine","Chromatography, High Pressure Liquid","Evaluation Studies as Topic","Fluorescence Polarization","Humans","Immunoassay","Immunoenzyme Techniques","Quality Control","Theophylline"],"mesh_terms":["Caffeine","Chromatography, High Pressure Liquid","Evaluation Studies as Topic","Fluorescence Polarization","Humans","Immunoassay","Immunoenzyme Techniques","Quality Control","Theophylline"],"keywords":["Theophylline","Chromatography","Theobromine","Chemistry","Caffeine","Paraxanthine","Solid phase extraction","High-performance liquid chromatography","Cartridge","Extraction (chemistry)","Sample preparation","Acetic acid","Materials science","Pharmacology","Biochemistry"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Clean water and sanitation"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-08T15:47:13.546664Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}