Name: calibrating lab glassware for accurate volume
Uploaded: 2024-12-05T18:31:54.000Z
Duration: 1 min 11 s
Channel: JoVE

正確な体積測定は、ソリューションベースの分析に不可欠です。標準的な容積測定機器には、フラスコ、ピペット、ビュレットが含まれます。
メスフラスコは、特定の容量の溶液を調製し、希釈するために使用されます。それらは「封じ込める」の略であるTCとマークされています。
これらは、指定された温度で正確な体積を含むように校正されており、ガラス膨張の最小係数により、わずかな変更にもかかわらずほぼ一定の体積が可能になります。
TDとラベル付けされたピペットは、特定の温度で特定の容量を供給します。これらは、納期によって異なるガラス壁のフィルムの排水を考慮して校正されています。
適切なキャリブレーションが施された容量ピペットは、有効数字が最大4桁または5桁の1つの容量を正確に供給します。測定用ピペットは、最大有効数字3桁という低い精度で異なる容量を提供します。
ビュレットは、滴定液を保持するための校正済みチューブで、滴定液の流れを制御するために手動バルブシステムを介して正確に分注することができます。

ガラス器具の較正

メスフラスコ、ピペット、ビュレットなどのガラス器具の正確な較正は、分析ラボで正確な測定を行うために不可欠です。較正は、測定間の一貫性を維持し、不正確な容量から生じる誤差を防ぐのに役立ちます。

メスフラスコは、首に較正線があり、正確な容量の水溶液を正確に調製できるように設計されています。メスフラスコを較正するには、メニスカス (液体の曲面) が較正マークと揃うまで蒸留水で満たすことが重要です。目の高さでメニスカスを見ると、正確な測定値が得られます。較正は通常、温度が容量に与える影響を考慮して、特定の温度 (約 20°C) で実行されます。水位が線より上にある場合は、マークに達するまで慎重に水を排出します。水位が線より下にある場合は、マークに達するまで水を滴下します。較正後、フラスコの容量は、水の重量を量り、密度に基づく理論値と比較することで確認できます。

ピペット

ピペットは、特定の量の液体を移すために使用されます。

メスピペット: これらは、通常 4 桁または 5 桁の有効数字で、単一の非常に正確な量を供給するように設計されています。較正では、まずピペットを洗浄して測定対象の溶液ですすぎ、較正マークまで満たし、容器に完全に排出させます。次に、供給された水の重量を量り、これを水の密度に基づく理論量と比較することで精度を確認します。

目盛り付きピペット: メスピペットとは異なり、目盛り付きピペットには一連の線が付いており、複数の量を供給できますが、精度はわずかに低く、通常は最大 3 桁の有効数字です。較正および測定中は、メニスカスも注意深く観察する必要があります。

ビュレット

ビュレットは、特に滴定で、さまざまな量の溶液を正確に分配する、片端に蛇口が付いた長い目盛り付きガラス管です。ビュレットを較正する際は、滴定の前後でメニスカスが目盛りと正しく揃っていることを確認し、供給された水の重量を理論値と比較して、供給された量が予想どおりであることを確認します。ビュレットのリザーバーには、液体の量を示す目盛りが付いています。底部のコックまたは蛇口は手動バルブとして機能し、使用者はリザーバーからの液体の流れを制御して、供給された量を正確に測定できます。

その他のガラス器具

メスシリンダーなどの他の種類の実験室用ガラス器具も、体積測定によく使用されますが、体積測定装置よりも精度が低くなります。通常、これらは最大 3 桁の有効数字で供給され、それほど精密ではない作業に適しています。ただし、これらのアイテムの較正は、測定の信頼性を維持するために依然として重要です。

実験室用ガラス器具を較正すると、正確で信頼性の高い測定が保証されます。これは、分析結果の整合性を維持するために不可欠です。メスフラスコ、ピペット、ビュレット、またはその他のガラス器具のいずれを使用する場合でも、適切な較正技術は、誤差を防ぎ、実験室作業の精度を向上させるのに役立ちます。

メスフラスコ、ピペット、ビュレットなどのガラス器具の正確な校正は、分析フラスコ、ピペット、ビュレットなどの正確な測定を確保するために不可欠です。

Education

JoVE Core

Analytical Chemistry

分析化学

Unit 1

ユニット1

Method Development and Sampling Techniques

分析法の開発およびサンプリング技術

method-development-and-sampling-techniques

KEY TERMS AND CONCEPTS

主要用語と概念

Glassware Calibration

calibrating lab glassware for accurate volume

Calibrating lab glassware helps students measure liquids accurately in the analytical laboratory. It reduces volume errors and supports consistent results across measurements. This matters when using volumetric flasks, pipettes, burettes, and other tools that depend on precise volume readings.

Volumetric flasks are used to prepare aqueous solutions with a precise final volume. They have a calibration line on the neck. To calibrate one, fill it with distilled water until the meniscus, the curved surface of the liquid, lines up with the mark at eye level. This is usually done at about 20°C because temperature can affect volume. If the water rises above the line, drain it carefully. If it is below the line, add water drop by drop until it reaches the mark. The flask’s capacity can then be checked by weighing the water and comparing it with the theoretical value from its density.

Pipettes are used to transfer set amounts of liquid. Volumetric pipettes are made to deliver one highly accurate volume, often to four or five significant figures. To calibrate one, clean it and rinse it with the solution to be measured, fill it to the calibration mark, and let it drain completely into a container. The volume delivered is checked by weighing the water and comparing it with the theoretical volume based on water density. Graduated pipettes have a series of marks and can deliver different volumes, but they are slightly less accurate. They are generally used to about three significant figures, so the meniscus must still be read carefully.

Burettes are long, graduated glass tubes with a tap at one end. They are used to dispense variable amounts of solution, especially during titrations. When a burette is calibrated, the meniscus must be aligned with the markings before and after use. The volume dispensed is then compared with the expected value by weighing the water delivered. The reservoir shows the liquid level, and the stopcock, or tap, acts as a manual valve that controls flow for precise measurement.

Other glassware, such as graduated cylinders, is also used for measuring volume. These tools are less accurate than volumetric equipment, but they are still useful for work that does not need the highest precision. They usually measure up to three significant figures. Even so, calibration remains important for reliable measurements in the lab. Careful calibration of lab glassware helps protect the accuracy and integrity of analytical results.

Calibrating Lab Glassware for Accurate Volume

calibrating-lab-glassware-for-accurate-volume

development of analytical methods

Analytical Methods: Technique to Protocol

Analytical methods follow a clear path from technique to protocol. In analytical chemistry, a technique is the scientific principle used to explain a chemical measurement. A method applies that technique to a sample of interest. The next steps are procedure and protocol. A procedure gives the directions for carrying out the analysis with an analytical method. A protocol is the detailed set of guidelines for that procedure, and it should be followed closely to get the desired results. <br...

quality control

Quality Control Charts and Lab Records

Quality control charts, proficiency testing, and lab records are key parts of quality control in a laboratory. These steps help keep a system under statistical control. They also help track data, show trends, and spot variations that may affect the accuracy of an analysis. One common tool is a quality control chart. This chart plots one or more analytical characteristics over time. The measured values are taken at different times during the analysis and compared with the known value of...

quality assurance

Quality Checks in Analytical Testing

Quality assurance in analytical testing brings together the checks that help a system perform properly. It includes quality control, quality assessment, and internal corrective measures. These parts work in a cycle to support reliable results. Quality control happens before and during the analysis. Quality assessment takes place during and after the investigation. Internal corrective measures are then based on the results of post-analysis quality assessment, or they may be applied before a new...

data validation

How Analytical Methods Are Checked

Method validation checks whether an analytical chemistry method gives reliable results. It is especially important when the same method is used with different sample matrices or when the procedure is changed. Validation helps show that the method still meets acceptable standards in each case. Several key checks are used in method validation. Specificity means the method can measure the target analyte without interference from other substances. Linearity means the result changes in direct...

qualitative analysis

Classical and Instrumental Sample ID

Qualitative analysis identifies the elements, ions, or compounds in an unknown sample. It is the first step in the hierarchy of analytical goals. That makes it the starting point for scientific study before quantitative analysis or other forms of analysis. Two main approaches are used in qualitative analysis: classical methods and instrumental methods. Classical methods depend on the visible or sensory result of a chemical reaction, such as a color change, a precipitate, or even a smell. These...

quantitative analysis

Measuring Analyte Concentration

Quantitative analysis measures the amount of a specific substance, called the analyte, in a sample. If the sample composition is unknown, qualitative analysis comes first. That step identifies the components so the correct substances can be measured during the quantitative phase. This method depends on two key measurements. Scientists measure the sample quantity and also a property that is proportional to the amount of analyte. Together, these measurements help determine the analyte...

instrument calibration

Calibrating Lab Instruments for Accurate Results

Calibration helps lab instruments produce accurate and consistent results. It is important in manufacturing, healthcare, testing laboratories, and scientific research. Each instrument needs a calibration process that matches its design and function. This process improves data accuracy and helps results stay reliable. An analytical balance measures mass and needs regular calibration to stay precise. It is calibrated by comparing its readings with known standard weights. These weights act as...

glassware calibration

Calibrating lab glassware helps students measure liquids accurately in the analytical laboratory. It reduces volume errors and supports consistent results across measurements. This matters when using volumetric flasks, pipettes, burettes, and other tools that depend on precise volume readings. Volumetric flasks are used to prepare aqueous solutions with a precise final volume. They have a calibration line on the neck. To calibrate one, fill it with distilled water until the meniscus, the...

standard solutions

Preparing Standard Solutions in the Lab

Standard solutions are prepared to have a precisely known concentration or composition. In analytical chemistry, this accuracy is important because it supports reliable results. A primary standard is a highly pure, stable substance with a high molar mass. It is fully soluble in water, which is the most commonly used solvent in analytical chemistry. A primary standard solution can be used to standardize a secondary standard. Secondary standards have known concentrations, but they are usually...

blank solutions

Blank Solutions in Analytical Testing

Blank solutions are used in analytical testing to show the background signal before a sample is measured. A blank solution does not contain the analyte, which is the substance of interest being tested or measured. It is usually made with the same reagents and procedure as the sample solution, but without the analyte. The main purpose of a blank solution is to control for background interference and contamination. Reagents, solvents, or lab equipment can sometimes create a detectable signal on...

sampling methods: overview

How Sampling Shapes Lab Results

Sampling shapes lab results by determining how a smaller sample represents a larger population. In analytical chemistry, testing an entire population is often impractical or impossible, so samples are collected to make inferences about the whole group. The sampling method is the process used to choose individuals or items for that sample. Common sampling methods include random, judgemental, systematic, stratified, and cluster sampling. Each method can affect the quality of the data in a...

sampling methods: sample types

Sampling Materials in Solid, Liquid, Gas

Sampling materials are grouped as solid, liquid, or gas. The type of sample helps decide the right collection method. Solid samples can include sediments from water bodies, soil, metals, and biological tissues. Sediment sampling from water bodies can be done in two common ways. Grab sampling uses a device to collect a discrete sample from the bottom with minimal disturbance. These samples may not show the full area because conditions can vary from place to place. Piston coring collects a...

sampling plans

Choosing Samples for Reliable Results

Sampling is a key step in analytical chemistry. It helps researchers collect data that represents a larger population. The main sampling methods in this topic are random, judgmental, systematic, stratified, and cluster sampling. Random sampling gives each member of the population an equal chance of being chosen. Researchers often use a random number generator or a lottery-style method. For example, a polymer sheet can be divided into 1 cm x 1 cm sections, and 10 sections can be selected at...

sample preparation for analysis: overview

Preparing Samples by State and Form

Sample preparation depends on the state and form of the sample before analysis. It helps make the sample ready for accurate measurement. The main goal is to extract the analyte, which is the substance being measured, and remove parts that could interfere with the analysis. Solid samples often need the most handling. Large solids are usually ground, crushed, or milled to make them smaller and increase surface area. The sample is then sieved and mixed so it has a uniform composition. After that,...

sample preparation for analysis: advanced techniques

sample-preparation-for-analysis-advanced-techniques

Preparing Complex Samples for Analysis

Preparing complex samples for analysis often requires special digestion and fusion methods. Samples with inorganic or organic material can be hard to dissolve or break down. Common sample preparation methods include acid digestion, fusion, dry ashing, and wet digestion. These steps help turn difficult samples into forms that can be tested reliably and again with similar results. Acid digestion is often used for inorganic materials that do not dissolve in water. It is useful for soil and...

sample handling

Sample Transport and Storage Basics

Sample transport and storage help keep specimens intact before testing. Moving a sample from the collection point to the laboratory requires careful handling. The sample should be sealed well and clearly labeled. These steps help prevent cross-contamination and support reliable results. Temperature control is also important during transport. Some samples travel in insulated containers, cool packs, or refrigerated vehicles so they stay within the needed temperature range. After the samples...

contaminants and errors

Sampling Errors in Sample Preparation

Sampling errors in sample preparation can affect the accuracy of laboratory results. Two common problems are concentration bias from poor sample splitting and contamination from reducing particle size by grinding or homogenization. Recognizing these errors helps make analysis more reliable. The number of samples also matters when a target population follows a normal distribution. In that case, the sample size ns can be found with a formula that uses the t-value for the chosen confidence level,...

key terms and concepts

Learn how volumetric flasks, pipettes, burettes, and graduated cylinders are calibrated to improve volume accuracy, consistency, and lab reliability.

Calibrating Lab Glassware for Accurate Volume | JoVE K12

JoVE Core 分析化学 は、複雑な化学原理をアニメーションで視覚化することで、SI 単位から NMR 分光法を含むトピックをよりわかりやすくします。実験を撮影した実写動画では、これらの概念が世界中の研究所でどのように応用されているかを取り上げています。

analytical chemistry

Calibrating Lab Glassware for Accurate Volume

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