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Illustration on How to Clean and Handle the Different Types of Lab Glassware

How to Clean and Handle the Different Types of Lab Glassware

Reference to this article: ConductScience, How to Clean and Handle the Different Types of Lab Glassware (2022). doi.org/10.55157/CS20220621

Glassware is used to store, mix, measure, deliver, and store biological and chemical substances or reactions in laboratories.

Since glass is inert, chemically neutral, and heat-resistant, lab glassware does not interact with the chemicals and can withstand high temperatures. Most glassware in the lab is colorless and transparent, allowing users to observe the substance or its transformation in the glassware.

However, Amber glassware are brown (not transparent) and used to store and handle light-sensitive chemicals or reactions. The amber-brown color limits the light from the surrounding, preventing unwanted decay or interference.   

Types of Glasses for Lab Glassware

Glassware found in most laboratories can be classified based on its composition:[1]

1. Borosilicate Glass

Also referred to as Type I lab glassware, borosilicate glasses are the most common type of glassware in most laboratories. It is primarily composed of silica and boric oxide, and the glass is known for durability, corrosion resistance, and non-reactivity to most acids and bases.

Borosilicate glassware is resistant to high temperature, pressure, and thermal expansion, allowing the lab glassware to be sterilized by autoclaving, which is performed under high pressure and temperature, in addition to chemical sterilization.

2. Soda-lime Glass

Type II or soda-lime glasses contain alkali earth, such as calcium oxide, magnesium oxide, and silica oxide. They are chemically inert and durable but generally less resistant to high temperatures than borosilicate glass. Thus, contaminated soda-lime glassware cannot be decontaminated by autoclaving like borosilicate glassware. 

3. Quartz Glass

Quartz glass comprises silica with little impurities from other elements. It possesses good elasticity, high resistivity, low thermal conductivity, and compressive strength. The glass can be shaped and molded into various forms.

Nonetheless, glassware made from quartz is the most expensive glassware in laboratories. It is lightweight and should not be sterilized by autoclaving or cleaned in a dishwasher. Instead, quartz glassware should be wiped and rinsed with deionized water or soaked in mild detergent before rinsing several times with deionized water.

Check out our complete guide on lab glassware’s physical and chemical properties to learn more about glassware.

Common Types of Lab Glassware

Glassware is shaped and designed for specific use in laboratories. Volumetric or graduated glassware is intended for measuring and delivering liquids, while others are used to transfer, incubate, store and mix chemicals.[2]

Common glassware found in laboratories are: 

1. Beakers

Beakers are flat-bottom cylindrical containers for transferring liquids, mixing, and heating samples. Beakers can accommodate solid and liquid samples ranging from 10mL to 5L. They have a graduated scale that indicates the volume of the sample. However, beakers have low accuracy – even graduated ones are prone to ±5% error.

2. Flasks

Flasks are containers with wide bottoms and narrow mouths, which can be closed by rubber or cork stoppers. They are used for mixing, heating, and boiling liquid samples.

  • Erlenmeyer flasks, also known as conical flasks, are general-purpose glassware used with magnetic stirring bars to mix and heat samples.
  • Filtering flasks are flasks with a tube connected to a conical part near the mouth of the flask. This tube is connected to a vacuum source, creating a vacuum inside the flasks. When used with a Büchner funnel on the top of the flask, the vacuum inside the flask will speed up the filtration process.
  • Boiling flasks are specifically designed for lab works that involve vigorous boiling, such as distillation and refluxing. They can be broadly classified into:
    • Florence flasks are boiling flasks with flat bottoms and round bodies often used when the flasks are heated on a flat surface.
  • Round bottom flasks, also called RB flasks, are boiling flasks with round bottoms and bodies. They are used with laboratory stands and clamps, which hold them in place during use.

3. Burettes

Burettes are glass tubes with a tap and valve at the outlet. They are used to precisely dispense small drops of liquid sample in titrations and measure the volume of liquid dispensed.

“Auto Zero” burettes are modified burettes attached to a bottle cap and immersed in the bottle’s liquid. In doing so, when liquid is filled into the burette, the excess liquid is automatically unloaded, and automatically, the volume is set to zero.

4. Pipettes

Pipettes are long and narrow glass tubes with a tapered tip. The liquid is drawn into the pipette from the tip with the help of a pipette bulb or pipette aid. Graduated pipettes are designed to precisely and accurately measure liquid samples. They are calibrated as “To Contain (TC)” or “To Deliver (TD)” liquid samples.

  • Volumetric pipettes are graduated pipettes designed to measure and transfer a specific amount of liquid. They are characterized by a bulgy middle, a graduation line, and numbers specifying the volume they can accommodate.
  • Serological or blow-out pipettes are graduated pipettes used to measure and transfer liquids. They accommodate a specific range of volume, ranging from 0.2-30mL. Serological pipettes are calibrated as TC. Thus, the liquid remaining in the pipette tips must be blown out to acquire the intended volume.  
  • Mohr pipettes or measuring pipettes are graduate pipettes similar to serological pipettes. Unlike serological pipettes, Mohr pipettes are calibrated as TD. For this reason, the remaining liquid in the tip of Mohr pipettes should not be blown out.
  • Pasteur pipettes or droppers are ungraduated pipettes used to transfer and dispense a small amount of liquid by drops.

Laboratory Glassware Selection Guide

When choosing and purchasing glassware for your laboratory, it is essential to understand the intended activities and applications.

Here are a few points that you should deliberate on:

  • Type of works and experiments dictate the necessary and appropriate type of glass and the lab glassware you should have. For example, borosilicate glassware is generally sufficient for most biochemical laboratories due to its durability and resistance to thermal and pressure stress. On the contrary, distillation and crystallization laboratories may also need a few quartz glassware because of its purity and superior compression strength.[2]  
  • Laboratory size and budget can play a major role in the quality and quantity of the glassware available in the laboratory. Depending on the type of work performed in the laboratory, some of the glassware can be replaced with plasticware, saving a substantial amount of money.[2]
  • Work and storage areas should also be factored into deciding the quantity and type of glass to purchase. In general, different types of glassware should be stored in separate and designated cabinets and shelves. Borosilicate glassware is heavier than quartz and soda-lime glassware. Thus, borosilicate glassware requires a strong and sturdy cabinet and shelf for storage.[2]

How to Clean Lab Glassware

Lab glassware is frequently exposed to chemical and biological samples, which can be toxic or even infectious. Therefore, contaminated glassware must be decontaminated by rinsing several times with warm tap water, soaking it in decontaminating solution, chemically sterilized, or autoclaved.

After decontamination, the waste should be discarded as per regulations. The decontaminated glassware should be further cleaned using commercial detergent.

If the decontaminated glassware is cleaned by hand, it should be soaked in warm, sudsy water before the glassware is washed with brushes and scrubs. Finally, the glassware can be thoroughly washed with water and rinsed with deionized water. Cleaned glassware can be air-dried or baked in a hot-air oven.[2]

Dos and Don’ts of Handling and Maintaing Lab Glassware

Lab glassware is designed for a specific purpose. It must be used for only its designated purpose, handled, and cleaned according to the standards.

Nonetheless, extra precautions should be given when using glassware in the following circumstances:[3]  

  • Heating glassware
    • Before heating the glassware to an extra high temperature (above 100°C), always consult with manufacturers.
    • Each piece of the glassware should be carefully inspected for chips and cracks before heating. If present, the glassware should not be heated regardless of the temperature used to prevent breakage and chemical spills.
    • Do not leave glassware heating for a long period, especially when the chemical is present when heating.
    • To avoid explosion, glassware rinsed with organic solvent must not be heated until the solvent is completely removed.
  • Cooling glassware
    • Like heating glassware, each piece of glassware must be inspected for chips and cracks before cooling or freezing it.
    • Change the temperature slowly to prevent glass shattering – this includes cooling to ultra-low temperature and thawing.
  • Glassware in a vacuum system
    • Avoid putting glassware in a vacuum or high-pressure condition because it could explode. Always consult with the manufacturer if and to what extent the specific piece of glassware can withstand high pressure and vacuum.
    • Diligently inspect glassware in a vacuum system for chips and cracks.
    • Obtain appropriate personal protective equipment when using glassware in a vacuum and pressure system.

Conclusion

Lab glassware is essential to every laboratory. Borosilicate glassware is the go-to glassware in most laboratories due to its durability and high temperature and pressure resistance. Each type of glassware is designed for a specific function and should be handled with care and precautions.  

Searching for quality and durable pipettes? Then check out our durable serological measuring pipette.

References:

  1. Schott. Technical Glasses: Physical and Technical Properties, Schott AG.
  2. Thompson R.B. Illustrated Guide to Home Chemistry Experiments, 1st edition, Maker Media, Inc., 2008.
  3. National Research Council of the National Academies. Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards, National Academy of Sciences, 2011.

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Introduction

In behavioral neuroscience, the Open Field Test (OFT) remains one of the most widely used assays to evaluate rodent models of affect, cognition, and motivation. It provides a non-invasive framework for examining how animals respond to novelty, stress, and pharmacological or environmental manipulations. Among the test’s core metrics, the percentage of time spent in the center zone offers a uniquely normalized and sensitive measure of an animal’s emotional reactivity and willingness to engage with a potentially risky environment.

This metric is calculated as the proportion of time spent in the central area of the arena—typically the inner 25%—relative to the entire session duration. By normalizing this value, researchers gain a behaviorally informative variable that is resilient to fluctuations in session length or overall movement levels. This makes it especially valuable in comparative analyses, longitudinal monitoring, and cross-model validation.

Unlike raw center duration, which can be affected by trial design inconsistencies, the percentage-based measure enables clearer comparisons across animals, treatments, and conditions. It plays a key role in identifying trait anxiety, avoidance behavior, risk-taking tendencies, and environmental adaptation, making it indispensable in both basic and translational research contexts.

Whereas simple center duration provides absolute time, the percentage-based metric introduces greater interpretability and reproducibility, especially when comparing different animal models, treatment conditions, or experimental setups. It is particularly effective for quantifying avoidance behaviors, risk assessment strategies, and trait anxiety profiles in both acute and longitudinal designs.

What Does Percentage of Time in the Centre Measure?

This metric reflects the relative amount of time an animal chooses to spend in the open, exposed portion of the arena—typically defined as the inner 25% of a square or circular enclosure. Because rodents innately prefer the periphery (thigmotaxis), time in the center is inversely associated with anxiety-like behavior. As such, this percentage is considered a sensitive, normalized index of:

  • Exploratory drive vs. risk aversion: High center time reflects an animal’s willingness to engage with uncertain or exposed environments, often indicative of lower anxiety and a stronger intrinsic drive to explore. These animals are more likely to exhibit flexible, information-gathering behaviors. On the other hand, animals that spend little time in the center display a strong bias toward the safety of the perimeter, indicative of a defensive behavioral state or trait-level risk aversion. This dichotomy helps distinguish adaptive exploration from fear-driven avoidance.

  • Emotional reactivity: Fluctuations in center time percentage serve as a sensitive behavioral proxy for changes in emotional state. In stress-prone or trauma-exposed animals, decreased center engagement may reflect hypervigilance or fear generalization, while a sudden increase might indicate emotional blunting or impaired threat appraisal. The metric is also responsive to acute stressors, environmental perturbations, or pharmacological interventions that impact affective regulation.

  • Behavioral confidence and adaptation: Repeated exposure to the same environment typically leads to reduced novelty-induced anxiety and increased behavioral flexibility. A rising trend in center time percentage across trials suggests successful habituation, reduced threat perception, and greater confidence in navigating open spaces. Conversely, a stable or declining trend may indicate behavioral rigidity or chronic stress effects.

  • Pharmacological or genetic modulation: The percentage of time in the center is widely used to evaluate the effects of pharmacological treatments and genetic modifications that influence anxiety-related circuits. Anxiolytic agents—including benzodiazepines, SSRIs, and cannabinoid agonists—reliably increase center occupancy, providing a robust behavioral endpoint in preclinical drug trials. Similarly, genetic models targeting serotonin receptors, GABAergic tone, or HPA axis function often show distinct patterns of center preference, offering translational insights into psychiatric vulnerability and resilience.

Critically, because this metric is normalized by session duration, it accommodates variability in activity levels or testing conditions. This makes it especially suitable for comparing across individuals, treatment groups, or timepoints in longitudinal studies.

A high percentage of center time indicates reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance. reduced anxiety, increased novelty-seeking, or pharmacological modulation (e.g., anxiolysis). Conversely, a low percentage suggests emotional inhibition, behavioral avoidance, or contextual hypervigilance.

Behavioral Significance and Neuroscientific Context

1. Emotional State and Trait Anxiety

The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity, where animals exhibit persistent avoidance of the center due to heightened emotional reactivity. This metric can also distinguish between acute anxiety responses and enduring trait anxiety, especially in longitudinal or developmental studies. Its normalized nature makes it ideal for comparing across cohorts with variable locomotor profiles, helping researchers detect true affective changes rather than activity-based confounds.

2. Exploration Strategies and Cognitive Engagement

Rodents that spend more time in the center zone typically exhibit broader and more flexible exploration strategies. This behavior reflects not only reduced anxiety but also cognitive engagement and environmental curiosity. High center percentage is associated with robust spatial learning, attentional scanning, and memory encoding functions, supported by coordinated activation in the prefrontal cortex, hippocampus, and basal forebrain. In contrast, reduced center engagement may signal spatial rigidity, attentional narrowing, or cognitive withdrawal, particularly in models of neurodegeneration or aging.

3. Pharmacological Responsiveness

The open field test remains one of the most widely accepted platforms for testing anxiolytic and psychotropic drugs. The percentage of center time reliably increases following administration of anxiolytic agents such as benzodiazepines, SSRIs, and GABA-A receptor agonists. This metric serves as a sensitive and reproducible endpoint in preclinical dose-finding studies, mechanistic pharmacology, and compound screening pipelines. It also aids in differentiating true anxiolytic effects from sedation or motor suppression by integrating with other behavioral parameters like distance traveled and entry count (Prut & Belzung, 2003).

4. Sex Differences and Hormonal Modulation

Sex-based differences in emotional regulation often manifest in open field behavior, with female rodents generally exhibiting higher variability in center zone metrics due to hormonal cycling. For example, estrogen has been shown to facilitate exploratory behavior and increase center occupancy, while progesterone and stress-induced corticosterone often reduce it. Studies involving gonadectomy, hormone replacement, or sex-specific genetic knockouts use this metric to quantify the impact of endocrine factors on anxiety and exploratory behavior. As such, it remains a vital tool for dissecting sex-dependent neurobehavioral dynamics.
The percentage of center time is one of the most direct, unconditioned readouts of anxiety-like behavior in rodents. It is frequently reduced in models of PTSD, chronic stress, or early-life adversity. Because it is normalized, this metric is especially helpful for distinguishing between genuine avoidance and low general activity.

Methodological Considerations

  • Zone Definition: Accurately defining the center zone is critical for reliable and reproducible data. In most open field arenas, the center zone constitutes approximately 25% of the total area, centrally located and evenly distanced from the walls. Software-based segmentation tools enhance precision and ensure consistency across trials and experiments. Deviations in zone parameters—whether due to arena geometry or tracking inconsistencies—can result in skewed data, especially when calculating percentages.

     

  • Trial Duration: Trials typically last between 5 to 10 minutes. The percentage of time in the center must be normalized to total trial duration to maintain comparability across animals and experimental groups. Longer trials may lead to fatigue, boredom, or habituation effects that artificially reduce exploratory behavior, while overly short trials may not capture full behavioral repertoires or response to novel stimuli.

     

  • Handling and Habituation: Variability in pre-test handling can introduce confounds, particularly through stress-induced hypoactivity or hyperactivity. Standardized handling routines—including gentle, consistent human interaction in the days leading up to testing—reduce variability. Habituation to the testing room and apparatus prior to data collection helps animals engage in more representative exploratory behavior, minimizing novelty-induced freezing or erratic movement.

     

  • Tracking Accuracy: High-resolution tracking systems should be validated for accurate, real-time detection of full-body center entries and sustained occupancy. The system should distinguish between full zone occupancy and transient overlaps or partial body entries that do not reflect true exploratory behavior. Poor tracking fidelity or lag can produce significant measurement error in percentage calculations.

     

  • Environmental Control: Uniformity in environmental conditions is essential. Lighting should be evenly diffused to avoid shadow bias, and noise should be minimized to prevent stress-induced variability. The arena must be cleaned between trials using odor-neutral solutions to eliminate scent trails or pheromone cues that may affect zone preference. Any variation in these conditions can introduce systematic bias in center zone behavior. Use consistent definitions of the center zone (commonly 25% of total area) to allow valid comparisons. Software-based segmentation enhances spatial precision.

Interpretation with Complementary Metrics

Temporal Dynamics of Center Occupancy

Evaluating how center time evolves across the duration of a session—divided into early, middle, and late thirds—provides insight into behavioral transitions and adaptive responses. Animals may begin by avoiding the center, only to gradually increase center time as they habituate to the environment. Conversely, persistently low center time across the session can signal prolonged anxiety, fear generalization, or a trait-like avoidance phenotype.

Cross-Paradigm Correlation

To validate the significance of center time percentage, it should be examined alongside results from other anxiety-related tests such as the Elevated Plus Maze, Light-Dark Box, or Novelty Suppressed Feeding. Concordance across paradigms supports the reliability of center time as a trait marker, while discordance may indicate task-specific reactivity or behavioral dissociation.

Behavioral Microstructure Analysis

When paired with high-resolution scoring of behavioral events such as rearing, grooming, defecation, or immobility, center time offers a richer view of the animal’s internal state. For example, an animal that spends substantial time in the center while grooming may be coping with mild stress, while another that remains immobile in the periphery may be experiencing more severe anxiety. Microstructure analysis aids in decoding the complexity behind spatial behavior.

Inter-individual Variability and Subgroup Classification

Animals naturally vary in their exploratory style. By analyzing percentage of center time across subjects, researchers can identify behavioral subgroups—such as consistently bold individuals who frequently explore the center versus cautious animals that remain along the periphery. These classifications can be used to examine predictors of drug response, resilience to stress, or vulnerability to neuropsychiatric disorders.

Machine Learning-Based Behavioral Clustering

In studies with large cohorts or multiple behavioral variables, machine learning techniques such as hierarchical clustering or principal component analysis can incorporate center time percentage to discover novel phenotypic groupings. These data-driven approaches help uncover latent dimensions of behavior that may not be visible through univariate analyses alone.

Total Distance Traveled

Total locomotion helps contextualize center time. Low percentage values in animals with minimal movement may reflect sedation or fatigue, while similar values in high-mobility subjects suggest deliberate avoidance. This metric helps distinguish emotional versus motor causes of low center engagement.

Number of Center Entries

This measure indicates how often the animal initiates exploration of the center zone. When combined with percentage of time, it differentiates between frequent but brief visits (indicative of anxiety or impulsivity) versus fewer but sustained center engagements (suggesting comfort and behavioral confidence).

Latency to First Center Entry

The delay before the first center entry reflects initial threat appraisal. Longer latencies may be associated with heightened fear or low motivation, while shorter latencies are typically linked to exploratory drive or low anxiety.

Thigmotaxis Time

Time spent hugging the walls offers a spatial counterbalance to center metrics. High thigmotaxis and low center time jointly support an interpretation of strong avoidance behavior. This inverse relationship helps triangulate affective and motivational states.

Applications in Translational Research

  • Drug Discovery: The percentage of center time is a key behavioral endpoint in the development and screening of anxiolytic, antidepressant, and antipsychotic medications. Its sensitivity to pharmacological modulation makes it particularly valuable in dose-response assessments and in distinguishing therapeutic effects from sedative or locomotor confounds. Repeated trials can also help assess drug tolerance and chronic efficacy over time.
  • Genetic and Neurodevelopmental Modeling: In transgenic and knockout models, altered center percentage provides a behavioral signature of neurodevelopmental abnormalities. This is particularly relevant in the study of autism spectrum disorders, ADHD, fragile X syndrome, and schizophrenia, where subjects often exhibit heightened anxiety, reduced flexibility, or altered environmental engagement.
  • Hormonal and Sex-Based Research: The metric is highly responsive to hormonal fluctuations, including estrous cycle phases, gonadectomy, and hormone replacement therapies. It supports investigations into sex differences in stress reactivity and the behavioral consequences of endocrine disorders or interventions.
  • Environmental Enrichment and Deprivation: Housing conditions significantly influence anxiety-like behavior and exploratory motivation. Animals raised in enriched environments typically show increased center time, indicative of reduced stress and greater behavioral plasticity. Conversely, socially isolated or stimulus-deprived animals often show strong center avoidance.
  • Behavioral Biomarker Development: As a robust and reproducible readout, center time percentage can serve as a behavioral biomarker in longitudinal and interventional studies. It is increasingly used to identify early signs of affective dysregulation or to track the efficacy of neuromodulatory treatments such as optogenetics, chemogenetics, or deep brain stimulation.
  • Personalized Preclinical Models: This measure supports behavioral stratification, allowing researchers to identify high-anxiety or low-anxiety phenotypes before treatment. This enables within-group comparisons and enhances statistical power by accounting for pre-existing behavioral variation. Used to screen anxiolytic agents and distinguish between compounds with sedative vs. anxiolytic profiles.

Enhancing Research Outcomes with Percentage-Based Analysis

By expressing center zone activity as a proportion of total trial time, researchers gain a metric that is resistant to session variability and more readily comparable across time, treatment, and model conditions. This normalized measure enhances reproducibility and statistical power, particularly in multi-cohort or cross-laboratory designs.

For experimental designs aimed at assessing anxiety, exploratory strategy, or affective state, the percentage of time spent in the center offers one of the most robust and interpretable measures available in the Open Field Test.

Explore high-resolution tracking solutions and open field platforms at

References

  • Prut, L., & Belzung, C. (2003). The open field as a paradigm to measure the effects of drugs on anxiety-like behaviors: a review. European Journal of Pharmacology, 463(1–3), 3–33.
  • Seibenhener, M. L., & Wooten, M. C. (2015). Use of the open field maze to measure locomotor and anxiety-like behavior in mice. Journal of Visualized Experiments, (96), e52434.
  • Crawley, J. N. (2007). What’s Wrong With My Mouse? Behavioral Phenotyping of Transgenic and Knockout Mice. Wiley-Liss.
  • Carola, V., D’Olimpio, F., Brunamonti, E., Mangia, F., & Renzi, P. (2002). Evaluation of the elevated plus-maze and open-field tests for the assessment of anxiety-related behavior in inbred mice. Behavioral Brain Research, 134(1–2), 49–57.

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