Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Experimental Designs01:16

Experimental Designs

An experimental design is a systematic process that allows researchers to evaluate the relationship between dependent and independent variables. There are three widely used types of experimental design - pre-experimental design, true experimental design, and quasi-experimental design. In pre-experimental design, the researcher compares the data before and after some interventions or treatments. The true-experimental design has more than one purposefully created group, a commonly measured...
Stimulants01:29

Stimulants

Stimulants are substances that enhance neural activity and elevate dopamine levels in the brain, leading to their highly addictive nature. These drugs include cocaine, amphetamines, MDMA, caffeine, and nicotine, each with distinct mechanisms of action and varied health implications.
Cocaine can be administered via snorting, injection, or smoking. It primarily functions by blocking the reuptake of dopamine, resulting in a euphoric high characterized by an intense sensation of happiness and...
Insomnia01:27

Insomnia

Insomnia is a prevalent sleep disorder characterized by difficulty falling asleep, frequent awakenings during the night, and waking up too early without being able to return to sleep. People with insomnia often experience these disruptions at least three nights a week for at least one month. Chronic insomnia, which lasts for at least three months, can lead to increased anxiety, which in turn can worsen sleep difficulties, creating a cycle of sleeplessness and stress.
Multiple factors contribute...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Adrenergic Agonists: Mixed-Action Agents01:28

Adrenergic Agonists: Mixed-Action Agents

Mixed-action adrenergic agonists, like ephedrine and pseudoephedrine, directly and indirectly affect adrenergic receptors. These agents stimulate adrenoceptors and indirectly release stored neurotransmitters, amplifying the adrenergic response.
Ephedrine and pseudoephedrine lack a catecholamine group, making them less susceptible to degradation by metabolic enzymes. They have increased oral bioavailability and lipophilicity, resulting in a longer duration of action. Their response is reduced by...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Postmortem case series of Δ<sup>8</sup>- and Δ<sup>9</sup>-tetrahydrocannabinol in blood and urine.

International journal of legal medicine·2026
Same author

Prevalence of p-fluorofentanyl and xylazine in postmortem fentanyl casework.

Journal of analytical toxicology·2026
Same author

Δ<sup>8</sup>-tetrahydrocannabinol, Δ<sup>9</sup>-tetrahydrocannabinol, and cannabidiol carboxylic acid metabolites in authentic meconium samples.

Journal of forensic sciences·2026
Same author

Drug positivity, co-detection patterns, and demographic predictors in patients seeking substance use disorder treatment, United States, 2023.

Addictive behaviors·2026
Same author

Prevalence of N,N-Dimethylpentylone in forensic toxicology casework: A retrospective study and trends in the state of Florida.

Forensic science international·2026
Same author

Case series involving the synthetic cathinones alpha-PHP, alpha-PiHP, MDPHP, and MDPiHP in forensic investigations.

Forensic science international·2026

Related Experiment Video

Updated: Jun 28, 2026

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions
09:11

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions

Published on: October 2, 2018

Caffeine content of brewed teas.

Jenna M Chin1, Michele L Merves, Bruce A Goldberger

  • 1Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, P.O. Box 100275, Gainesville, Florida 32610-0275, USA.

Journal of Analytical Toxicology
|November 15, 2008
PubMed
Summary

Most teas contain less caffeine than coffee, with concentrations varying by brew time. Decaffeinated teas had minimal caffeine, while herbal teas contained none. This study analyzed caffeine levels in 20 commercial tea products.

More Related Videos

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment
04:36

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment

Published on: May 26, 2023

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves
10:35

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

Published on: June 15, 2019

Related Experiment Videos

Last Updated: Jun 28, 2026

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions
09:11

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions

Published on: October 2, 2018

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment
04:36

Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment

Published on: May 26, 2023

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves
10:35

Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (Camellia Sinensis L.) Leaves

Published on: June 15, 2019

Area of Science:

  • Food Science
  • Analytical Chemistry
  • Pharmacology

Background:

  • Caffeine is a widely consumed psychostimulant found in beverages like tea.
  • Understanding caffeine content in commercial teas is crucial for consumers and regulatory bodies.

Purpose of the Study:

  • To quantify caffeine concentrations in various commercial tea products.
  • To investigate the impact of brewing parameters (serving size, steep-time) on caffeine levels.

Main Methods:

  • Liquid-liquid extraction was used to isolate caffeine from tea samples.
  • Gas chromatography with nitrogen-phosphorus detection (GC-NPD) quantified caffeine content.
  • Analysis included white, green, black, decaffeinated, and herbal teas brewed under different conditions.

Main Results:

  • Caffeine levels in white, green, and black teas ranged from 14-61 mg per 6-8 oz serving.
  • Decaffeinated teas contained <12 mg caffeine per serving; herbal teas had no detectable caffeine.
  • Steep-time significantly influenced caffeine concentration, while serving size had minimal effect.

Conclusions:

  • Brewed tea generally contains less caffeine per serving than brewed coffee.
  • Brewing time is a key factor influencing the final caffeine content of tea.
  • Tea variety did not show a clear trend in caffeine concentration.