Name: preparing standard solutions in the lab
Uploaded: 2024-12-05T18:31:54.000Z
Duration: 1 min 14 s
Channel: JoVE

標準溶液とは、正確に既知の量の物質を含む溶液です。高純度、高分子量、親水性、安定な物質である一次標準物質から調製されています。
調製には、計量ボート内の一次標準品の適切な量を正確に計量し、漏斗を使用してメスフラスコに移すことが含まれます。空の計量ボートは、残っている固体物質をチェックするために再計量されます。
少量の蒸留水を加えて、漏斗の固形物をフラスコに洗い流します。容積フラスコを渦巻いて固体を完全に溶解します。そのレベルがキャリブレーションマークに近づくまで、さらに水が追加されます。この時点で、水はピペッティングされ、溶液レベルがキャリブレーションマークまで正確に増加します。
フラスコは数回閉じて反転させ、完全に混合します。フラスコに化学組成、濃度、および調製日をラベル付けします。
この一次標準液は、純度が低く、安定性の低い物質である二次標準を標準化するために使用されます。

標準溶液

標準溶液とは、正確に濃度または組成がわかっている溶液を指します。一次標準は、分析化学で最も一般的に使用される溶媒である水に完全に溶解する、高純度で高モル質量の安定した物質です。一次標準溶液は、濃度はわかっているが純度と安定性が低い物質である二次標準を標準化するために使用できます。標準溶液は、分析手順で正確で信頼性の高い結果を得るために不可欠であるため、実験室環境で作業する人にとって理解が重要です。

一次標準を使用した標準溶液の準備には、いくつかの手順があります。

<ul style="list-style-type: disc; display: flex; flex-direction: column; padding: 0 0 0 30px;">
	<li>一次標準の重量を量る: 計量ボートを使用して、適切な量の一次標準を計量します。正確な測定ができる計量天秤を使用することが重要です。</li>
	<li>標準をメスフラスコに移す: 漏斗を使用して、重量を量った一次標準を清潔で乾燥したメスフラスコに慎重に移します。すべての固体が計量ボートからフラスコに移されていることを確認します。移した後、空の計量ボートを再度計量して、残留物が残っていないことを確認します。 </li>
	<li>漏斗を洗浄する: 少量の蒸留水を使用して、漏斗から固形物をメスフラスコに洗い流します。これにより、すべての一次標準が溶液に溶解されます。</li>
	<li>固形物を溶解する: 固形物が完全に溶解するまでメスフラスコを回します。固形物が完全に溶解するまで、水を徐々に追加する必要がある場合があります。</li>
	<li>較正線に近づく: 蒸留水をさらに追加して、溶液のレベルをメスフラスコの首の較正マークに近づけます。較正線を超えないように、溶媒を追加する前に固形物が完全に溶解していることを確認してください。</li>
	<li>メニスカスを調整する: ピペットを使用して、メニスカスの底 (液体の表面の曲線) が較正マークと正確に一致するまで、水を一滴ずつ追加します。この手順により、溶液の容量と濃度が適切になります。</li>
	<li>溶液を混合する: メスフラスコをしっかりと閉じ、数回逆さまにして、溶液が完全に混合されていることを確認します。</li>
	<li>ラベル: 化学組成、溶液の濃度、調製日を記載したラベルをメスフラスコに貼ります。この情報は溶液を正しく識別し、使用するのに役立ちます。</li>
</ul>

標準溶液とは、濃度または組成が正確に知られている溶液を指します。一次標準は、高純度、高分子量、安定しています...

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

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 less pure and less stable. This makes primary standards especially useful when exact measurements are needed in a laboratory setting.

The preparation starts by weighing the primary standard with a balance that gives precise measurements. The solid is then transferred through a funnel into a clean, dry volumetric flask. It is important to move all of the material from the weighing boat into the flask. The empty weighing boat is reweighed to confirm that no residue remains.

Next, small amounts of distilled water are used to wash any solid from the funnel into the volumetric flask. The flask is then swirled until the solid dissolves completely. More water is added gradually until the liquid is close to the calibration line on the neck of the flask.

The final volume is set by adjusting the meniscus, which is the curved surface of the liquid. A pipette is used to add water drop by drop until the bottom of the meniscus lines up exactly with the calibration mark. The flask is then closed and inverted several times to mix the solution well. At the end, the flask is labeled with the chemical composition, the solution concentration, and the preparation date.

Preparing Standard Solutions in the Lab

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 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...

standard solutions

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 standard solutions are prepared from a primary standard using a volumetric flask, accurate weighing, meniscus adjustment, and proper labeling.

Preparing Standard Solutions in the Lab | 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

Preparing Standard Solutions in the Lab

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