A method for determining submicrogram-per-liter concentrations of caffeine in surface water and groundwater samples has been developed. Caffeine is extracted from a 1 L water sample with a 0.5 g graphitized carbon-based solid-phase cartridge, eluted with methylene chloride-methanol (80 + 20, v/v), and analyzed by liquid chromatography with photodiode-array detection. The single-operator method detection limit for organic-free water samples was 0.02 μg/L. Mean recoveries and relative standard deviations were 93 ± 13% for organic- free water samples fortified at 0.04 μg/L and 84 ± 4% for laboratory reagent spikes fortified at 0.5 μg/L. Environmental concentrations of caffeine ranged from 0.003 to 1.44 μg/L in surface water samples and from 0.01 to 0.08 μg/L in groundwater samples.
Introduction Analytical Method 1. Application 2. Summary of method 3. Interferences 4. Apparatus and instrumentation 5. Reagents and solutions 6. Safety precautions 7. Procedure 8. Calculations 9. Reporting of results 10. Quality assurance/quality control 11. Method performance Conclusions References cited CONTENTS III 8. Mass spectrometer operating conditions during positive and negative ionization analyses used in this method 9a. Mass spectrometer time-programmed operating conditions for individual compounds determined under positive ionization conditions 9b. Mass spectrometer time-programmed operating conditions for individual compounds determined under negative ionization conditions 10. Quantitation and confirmation ions used for the compounds determined in this method 11. Autotune parameters for acceptable tuning criteria used in this method 12. Typical minimum sample analysis sequence for high-performance liquid chromatography/mass spectrometry analysis in this method 13. Accuracy and precision data from 10 determinations of the method compounds fortified at 0.025 microgram per liter in organic-free water, under positive ionization conditions 14. Accuracy and precision data from 10 determinations of the method compounds fortified at 0.025 microgram per liter in organic-free water, under negative ionization conditions 15. Accuracy and precision data from seven determinations of the method compounds fortified at 0.10 microgram per liter in organic-free water, under positive ionization conditions 16. Accuracy and precision data from seven determinations of the method compounds fortified at 0.10 microgram per liter in organic-free water, under negative ionization conditions 17. Accuracy and precision data from nine determinations of the method compounds fortified at 0.50 microgram per liter in organic-free water, under positive ionization conditions 18. Accuracy and precision data from nine determinations of the method compounds fortified at 0.50 microgram per liter in organic-free water, under negative ionization conditions 19. Accuracy and precision data from 10 determinations of the method compounds fortified at 0.025 microgram per liter in groundwater samples, under positive ionization conditions 20. Accuracy and precision data from nine determinations of the method compounds fortified at 0.025 microgram per liter in groundwater samples, under negative ionization conditions 21. Accuracy and precision data from six determinations of the method compounds fortified at 0.10 microgram per liter in groundwater samples, under positive ionization conditions 22. Accuracy and precision data from six determinations of the method compounds fortified at 0.10 microgram per liter in groundwater samples, under negative ionization conditions 23. Accuracy and precision data from 11 determinations of the method compounds fortified at 0.50 microgram per liter in groundwater samples, under positive ionization conditions 24 Accuracy and precision data from 10 determinations of the method compounds fortified at 0.50 microgram per...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.