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

機器のキャリブレーションにより、確定的な誤差のない正確な測定が保証されます。
キャリブレーションとは、標準器を使用して機器の測定信号を調整することです。たとえば、質量を測定する分析天びんは、基準として標準分銅に対して校正する必要があります。
ここでは、空気の浮力によって決定的な誤差が生じる可能性があり、これにより物体は真空中よりも空気中よりも軽くなります。計量対象の物体とキャリブレーションの分銅との間の密度の不一致は、物体の重量に補正を適用することで解決されます。
物体の真の重量と空気中の重量との関係は、標準的な実験室条件下での物体の密度、校正重量、および空気を考慮します。
DOとDwの間の不一致の程度は、測定された重量の誤差に直接影響します。
分光光度計のキャリブレーションには、既知の分析物濃度を持つ標準溶液の調製が含まれます。それらを測定することで、未知の濃度を決定するための検量線が生成されます。

機器の較正

機器の較正は、機器が正確で一貫した結果を生み出すために不可欠です。これは、製造、医療、試験所、科学研究において不可欠です。較正プロセスは各機器に固有のものであり、データの精度を高めるのに役立ちます。各機器には、データの精度を向上させるために、設計と機能に合わせて調整された独自の較正プロセスがあります。

分析天びんの較正

分析天びんは質量を測定し、精度を維持するために定期的な較正が必要です。較正は、測定値を既知の標準重量と比較することによって行われます。これらの標準重量は、正確な質量測定値を確保するための基準として機能します。分析天びんは、空気の浮力などの外部要因の影響を受ける可能性があります。空気の浮力により、重量のある物体は真空中では実際の重量よりも軽く見えます。物体の密度、空気の密度、較正重量を考慮して、浮力補正を適用して天びんを較正します。空気の浮力によって生じる確定的な誤差に対処することで、分析天びんは物体の実際の重量をより正確かつ確実に測定します。

分光光度計の較正

分光光度計は溶液による光の吸光度を測定する機器で、質量測定とは異なります。較正には、既知の分析物濃度の標準溶液を使用して較正曲線を作成します。このプロセスは、通常、低濃度から高濃度までの範囲の一連の標準溶液を準備して、幅広い較正曲線を形成することから始まります。次に、分光光度計を使用して各標準溶液の吸光度を測定します。分光光度計は溶液に光を当て、分析物によって吸収される光の量を測定します。

吸光度の値は、既知の濃度に対してプロットされます。ランベルト・ベールの法則によると、このプロットは直線を形成し、濃度と吸光度の間に直接的な関係があることを示します。較正曲線が確立されると、未知の溶液の吸光度を測定します。この吸光度の値は、較正曲線から未知の溶液内の分析物の対応する濃度を決定するのに役立ちます。

機器のキャリブレーションは、機器が正確で一貫性のある結果を生成するために不可欠です。それは製造業、ヘルスケア、...

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

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 references for correct mass measurements. Air buoyancy can affect the balance because it can make a weighted object seem lighter than it really is in a vacuum.

A buoyancy correction is used to adjust for that error. The correction depends on the object&amp;#39;s density, the air density, and the calibration weights. By accounting for the determinate error caused by air buoyancy, the analytical balance gives a more accurate reading of an object&amp;#39;s true weight.

A spectrophotometer is calibrated in a different way because it measures how much light a solution absorbs. The process uses a calibration curve made from standard solutions with known analyte concentrations. First, a series of standards is prepared from low to high concentration to create a broad curve. Then each standard is measured for absorbance.

The spectrophotometer shines light through the solution and records how much is absorbed by the analyte. The absorbance values are plotted against the known concentrations. According to the Beer-Lambert law, the plot should be a straight line, showing a direct link between concentration and absorbance. After the curve is made, an unknown solution can be measured, and its absorbance is used to find the analyte concentration from the curve.

Calibrating Lab Instruments for Accurate Results

calibrating-lab-instruments-for-accurate-results

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

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

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 calibration improves accuracy in analytical balances and spectrophotometers, using standard weights, buoyancy correction, and calibration curves.

Calibrating Lab Instruments for Accurate Results | 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 Instruments for Accurate Results

Description

Transcript