Name: preparing complex samples for analysis
Uploaded: 2024-12-05T18:31:55.000Z
Duration: 1 min 8 s
Channel: JoVE

무기 분석을 위한 시료 전처리 방법은 물질의 특성에 따라 다릅니다.
물에 녹지 않는 많은 무기 물질은 강한 무기산을 사용하여 가용화될 수 있습니다. 여전히 용해되지 않은 경우 융합 기술로 알려진 보다 집약적인 방법이 사용됩니다.
여기서, 시료의 무게를 측정하고 약 1 내지 10 또는 20의 비율로 플럭스 물질과 혼합한다. 샘플-플럭스 혼합물을 백금 도가니에서 가열하여 용융 혼합물을 얻습니다. 냉각시 이것은 응고되어 물 또는 묽은 산에 용해되는 새로운 물질을 생성합니다.
대조적으로, 유기 물질은 건조 회분 및 습식 소화 방법에 의해 분해됩니다. 건조 애싱에서 샘플은 대기 산소가 있는 머플 용광로에서 가열됩니다. 여기서, 유기 물질의 연소는 추가 분석을 위한 무기 잔류물을 생성합니다.
습식 소화는 유기 물질을 분해하기 위해 산 혼합물을 사용합니다.

분석을 위한 표본 준비: 고급 기술

복잡한 표본을 정확하게 분석하려면 신뢰할 수 있고 재현 가능한 결과를 얻기 위해 고급 준비 기술이 필요한 경우가 많습니다. 무기 또는 유기 물질이 포함된 표본은 효과적으로 용해하거나 분해하기 어려울 수 있습니다. 표준 표본 준비 방법에는 산 분해, 융합, 건식 회분화 및 습식 분해가 있습니다.

강산을 사용한 산 분해는 일반적으로 물에 녹지 않는(용해되지 않는) 무기 물질을 용해하는 데 사용됩니다. 이 방법은 토양 또는 광물 표본을 분석하는 데 유용할 수 있습니다. 산 분해 중에 불용성 고체 표본은 표면적을 늘리기 위해 미세하게 분쇄되거나 으깨져 산과 더 효과적으로 반응할 수 있습니다. 일반적으로 사용되는 산에는 염산, 질산, 황산 및 왕수(질산과 염산의 혼합물)가 있습니다. 각 산은 표본 유형에 따라 특정한 장점이 있습니다.

<ul style="list-style-type: disc; margin-left: 35px;">
	<li>염산(HCl)은 종종 염화물, 산화물 및 탄산염을 용해하는 데 사용되며 금속 및 광석과 같은 물질에도 효과적입니다.</li>
	<li>질산(HNO_3)은 유기물을 분해하고 금속을 산화하는 데 매우 뛰어나 생물학적 조직이나 금속 분석에 일반적으로 사용됩니다.</li>
	<li>황산(H_2SO_4)은 황화물이나 금속과 같이 더 강한 내성을 가진 표본을 용해하는 경우와 같이 강력한 탈수제가 필요할 때 사용됩니다.</li>
	<li>질산과 염산의 혼합물인 왕수는 금과 백금과 같이 개별 산에 내성이 있는 귀금속을 용해하는 데 특히 효과적입니다.</li>
</ul>

표본은 적합한 용기에 선택한 고강도 산으로 처리하여 용해성 형태 또는 이온으로 분해합니다. 소화 과정을 가속화하기 위해 열을 가할 수도 있습니다. 소화 후 물로 희석한 결과 혼합물은 추가 분석에 적합합니다.

융합 기술은 산 소화로 용해성 형태로 분해할 수 없는 무기 물질을 용해하는 대체 방법입니다. 여기서, 가중된 표본은 일반적으로 약 1 대 10 또는 20의 특정 비율로 플럭스 재료와 혼합됩니다. 표본-플럭스 혼합물은 고온 및 화학 반응에 강한 백금 도가니에 넣습니다. 이 도가니는 고온로에서 가열되어 용융 혼합물을 얻습니다. 가열 후, 용융 혼합물은 물이나 희석된 산에 녹는 새로운 재료가 생성될 때까지 냉각됩니다.

고체 및 액체 화합물을 용해하기 위한 표본 준비에서 플럭스를 사용하는 몇 가지 예는 다음과 같습니다.

<ul style="list-style-type: disc; margin-left: 35px;">
	<li>철 및 크롬 합금용 플럭스로서의 Na_2CO_3 및 Na_2O_2: 탄산나트륨(Na_2CO_3)은 일반적으로 사용되는 플럭스이지만, 특정 경우에 더 강한 산화 능력으로 인해 과산화나트륨(Na_2O_2)이 사용됩니다. 이 조합은 니켈 도가니에서 철 및 크롬 합금을 용해하는 데 특히 유용합니다.</li>
	<li>빠른 용해를 위한 Li_2B_4O_7 및 Li_2SO_4 혼합물: 중량 기준으로 2:1 비율의 사붕산리튬(Li_2B_4O_7)과 황산리튬(Li_2SO_4)의 혼합물은 내화성 규산염과 산화물을 빠르게 용해하는 능력이 뛰어납니다.</li>
</ul>

건식 애싱 및 습식 소화 방법은 유기 물질을 분해하는 데 널리 사용됩니다. 건식 애싱에서 유기 표본은 고온의 머플로에서 가열됩니다. 열은 대기 산소가 있는 상태에서 유기 물질을 연소시켜 무기 잔류물 또는 '회분'을 남깁니다. 그런 다음 이 재를 추가 분석을 위해 적절한 용매에 녹일 수 있습니다. 습식 소화는 유기 물질을 분해하기 위해 산을 사용하는 것을 포함합니다.

복잡한 시료를 정확하게 분석하려면 신뢰할 수 있고 재현성 있는 결과를 얻기 위해 고급 전처리 기술이 필요한 경우가 많습니다. 다음을 포함하는 샘플 ...

sample-preparation-for-analysis-advanced-techniques

Education

교육

JoVE Core

Analytical Chemistry

분석 화학

Unit 1

제1단원

Method Development and Sampling Techniques

분석법 개발 및 시료 채취 기술

method-development-and-sampling-techniques

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 mineral samples. The solid sample is first finely ground or crushed to increase surface area, which helps it react better with the acid. Common acids include hydrochloric acid, nitric acid, sulfuric acid, and aqua regia, which is a mixture of nitric and hydrochloric acids.

Each acid has a different use. Hydrochloric acid, or HCl, is often used for chlorides, oxides, and carbonates, and it also works on metals and ores. Nitric acid, or HNO3, is good for breaking down organic matter and oxidizing metals, so it is often used for biological tissues or metal analysis. Sulfuric acid, or H2SO4, is useful when a strong dehydrating agent is needed, such as for more resistant sulfides or metals. Aqua regia is especially effective for noble metals like gold and platinum, which resist individual acids.

During digestion, the sample is placed in a suitable container and treated with the chosen strong acid. Heat may be added to speed up the process. The sample changes into soluble forms or ions, and the final mixture is diluted with water before further analysis. Fusion is another way to dissolve inorganic materials when acid digestion is not enough. In this method, the weighed sample is mixed with a flux in a ratio of about 1 to 10 or 20, then heated in a platinum crucible in a high-temperature furnace until it melts.

After cooling, the fused material becomes soluble in water or dilute acid. Some flux examples are sodium carbonate and sodium peroxide for iron and chromium alloys in a nickel crucible. Potassium disulfate, K2S2O7, works well for refractory oxides and can be made by heating potassium hydrogen sulfate to remove foaming byproducts. A mixture of lithium tetraborate and lithium sulfate in a 2:1 ratio is also used because it dissolves refractory silicates and oxides quickly.

Organic samples are often prepared by dry ashing or wet digestion. In dry ashing, the sample is heated in a muffle furnace at high temperature. The organic material burns in air and leaves behind an inorganic residue called ash. That ash can then be dissolved in a suitable solvent for analysis. Wet digestion also breaks down organic material, but it does so with acids.

Preparing Complex Samples for Analysis

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

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

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 acid digestion, fusion, dry ashing, and wet digestion prepare complex samples for analysis, including soil, minerals, metals, and organic tissue.

Preparing Complex Samples for Analysis | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Preparing Complex Samples for Analysis

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