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Chromatography

Chromatography is a set of techniques used to separate mixtures in a chemistry lab setting. The word chromatography means "color writing" and some of the first experiments in chromatography involved separating chlorophyll in plants.

649 Questions

Where is HPLC chromatography used in industry?

HPLC chromatography is widely used in industries such as pharmaceuticals, food and beverage, and environmental analysis for separating, identifying, and quantifying compounds in complex mixtures. It is commonly used for quality control testing, analyzing drug potency, detecting impurities, and monitoring environmental contaminants.

Where is paper chromatography used in industry?

Paper chromatography is commonly used in industries such as food and pharmaceuticals for analyzing the components of mixtures. It is useful for separating and identifying different compounds in a sample, determining purity levels, and monitoring consistency in production processes. Additionally, it is utilized in environmental testing for determining the presence of pollutants in water and air samples.

What is tailing in chromatography?

Tailing peaks are a known problem in chromatography (both HPLC and GC). It means the analytes are experiencing an out-drawn (extended) retention time and is usually due to one of these factors:

  • Contaminated or active injector liner, seal or column
  • Dead volume due to poorly installed liner or column
  • Ragged column end
  • A bad match between the polarities of the stationary phase and the solvent
  • A cold region in the sample flow path (GC)
  • Debris in the liner or column
  • Injection takes too long
  • Split ratio is too low (GC)
  • Overloading the inlet
  • Some types of compounds such as alcoholic amines, primary and secondary amines and carboxylic acids tend to tail

Why do different inks separate while using chromatography?

Different inks separate during chromatography because they contain different pigments with varying polarities. As the solvent moves up the paper, the pigments in the ink interact differently with the paper and solvent, causing some pigments to travel faster and further than others. This separation allows the individual pigments in the ink mixture to be identified by their distinct colors and positions on the chromatogram.

Who scraped the gatepost?

The gatepost was scraped by the car when it turned too sharply while entering or exiting the driveway.

What is the definition of zone broadening in chromatography?

this is where you zone into the paper with a magnifier glass and get a beaker of water and fill it to 50ml then you hold it up in the air and tip it onto the paper but you need to be looking at the paper with a magnifier glass when doing it

What are the recommendation for chromatography?

Some recommendations for chromatography include selecting the appropriate stationary phase and mobile phase, optimizing the flow rate for separation, ensuring proper column packing, and using high-quality standards for calibration and validation of results. It is also important to maintain consistent temperature and pressure conditions throughout the chromatographic process.

How can you analyze colorless substances using chromatography?

Colorless substances can be analyzed using chromatography by using detection methods that are sensitive to non-visible properties such as UV absorption or conductivity. For example, UV-Vis detectors can be used to measure the absorption of UV light by the sample as it passes through the detector, allowing for identification and quantification of colorless compounds. Conductivity detectors can also be used to measure the change in conductivity of the eluent as the sample passes through, providing information about the solutes present in the sample.

What are the two techniques used in paper chromatography to identify caffeine in tea?

The two techniques used in paper chromatography to identify caffeine in tea are stationary phase and mobile phase. In stationary phase, a sheet of filter paper is used to hold the sample, while in mobile phase, a solvent is used to carry the sample along the paper. These techniques separate the components of the sample based on their affinity for the stationary and mobile phases.

Why is that the centre of the spot is considered when calculating Rf values for TLC?

The center of the spot is considered when calculating Rf values in thin layer chromatography (TLC) because it provides a more consistent and accurate measurement point for comparing the distance traveled by the compound being analyzed to the distance traveled by the solvent front. This helps to standardize the Rf value calculation and allows for better reproducibility of results.

What is the function of the mobile phase for developing a chromatogram?

The mobile phase in chromatography is responsible for carrying the sample through the stationary phase. It helps separate the components of the sample by their different affinities for the stationary phase. The composition and flow rate of the mobile phase can be adjusted to optimize separation.

What is role of ion pair reagent in mobile phase of HPLC?

Ion pair reagents are used in HPLC to improve the separation of ionic compounds such as acids or bases. They work by forming ion pairs with the analytes, which helps to increase their retention on the stationary phase and improve their separation on the chromatographic column. This can lead to better peak shape, resolution, and sensitivity in the analysis.

Why do pharmaceutical techinicians use chromatography?

Pharmaceutical technicians use chromatography to separate and analyze complex mixtures of compounds in drugs. Chromatography helps in quality control, identifying impurities, and determining the concentration of active ingredients in pharmaceutical products. This analytical technique is crucial for ensuring the safety, efficacy, and quality of pharmaceutical products before they reach the market.

How can ink chromatography be used in forensic science?

Ink chromatography can be used in forensic science to analyze pen inks and determine if two or more inks are chemically similar, aiding in forgery detection. By separating the ink components, analysts can compare the ink profiles from different sources to provide evidence in cases involving counterfeiting or document fraud.

What does copper and sulphur and oxygen make?

Combining copper, sulfur, and oxygen together can form copper sulfate, which is a blue crystalline solid. This compound is commonly used in agriculture as a fungicide and herbicide.

How can you determine the purity of amino acid using paper chromatography?

To determine the purity of an amino acid using paper chromatography, you would first need to separate the amino acids using paper chromatography. Once the amino acids are separated on the paper, you can calculate the Rf value (retention factor) for each amino acid. Comparing the Rf values of the sample amino acid to a standard of known purity can help determine the purity of the sample.

What is it called when a mixture that appears to the same composition color and density and is mixed at the molecular level?

Solution: A mixture that appears to have the same composition, color, density, and taste, and is mixed at the atomic or molecular level.

Why is no locating agent needed when inks or grass pigments are analysed by chromatography?

Inks and grass pigments usually contain naturally occurring compounds that can act as locating agents, such as chlorophyll in grass pigments and dyes in inks. These compounds already have distinctive colors and properties that can easily indicate the separated components on the chromatogram without the need for an additional locating agent.

How does coloured rings form when chromatography is made?

Colored rings form during chromatography due to the separation of different components in a mixture based on their affinity for the stationary and mobile phases. As the components move through the chromatography medium at different rates, they separate into distinct bands or rings, each representing a different compound in the mixture. The coloration may result from the absorption of specific wavelengths of light by the separated compounds.

How can chromatography be used to identify amino acid?

Chromatography can be used to separate and analyze amino acids in a mixture based on their different chemical properties such as size, charge, and hydrophobicity. By comparing the retention times of known amino acids with those in the sample, identification can be achieved. The specific pattern of peaks obtained from the chromatogram can help in determining the presence and concentration of individual amino acids in the sample.

Which is a covalently bonded molecule cl2 air Ne or salt?

Cl2 is a covalently bonded molecule because it is composed of two nonmetal atoms that share electrons. Air is a mixture of gases, with nitrogen and oxygen being the main components, and these are also covalently bonded molecules. Neon is a noble gas and exists as individual atoms, not molecules. Salt is an ionic compound composed of a metal and a nonmetal held together by ionic bonds.

Why are mixtures to be separated by chromatography heated first before separated?

Heating the mixture in chromatography helps to increase the solubility of the components in the mobile phase, making them more likely to interact with the stationary phase and separate properly. Additionally, heating can reduce the viscosity of the mobile phase, allowing for better flow rates and improved separation efficiency.

How do you calculate Bandwidth W in chromatography?

Bandwidth in chromatography is typically calculated as the peak width at 5% of the peak height. This is done by measuring the width of the peak on the chromatogram at this 5% height point and can be used to assess the resolution and efficiency of the chromatographic separation. It is important in determining the quality and effectiveness of a chromatographic method.

How different colors are discovers what colors are in each ink using chromatography?

The different substances present in the ink have different Rf values (Rf value is the ratio of the distance the dissolved material traveled to distance the solvent traveled) the different substances each have a unique or nearly unique Rf value. This occurs because each material's chemical structure has a different solubility in the solvent,used to develop the chromatography plate,. This means that some compounds easily dissolve and are carried by the solvent while others are more attracted to the chromatgraphy plate and don't budge as easily.

Hope this helped.

sincerely,

a chem major

What is included volume in gel chromatography?

In gel chromatography, the included volume refers to the volume of the gel column through which a solute can pass without being significantly retarded. It is the volume of the gel matrix accessible to the solute molecules for separation. The included volume influences the resolution and efficiency of the chromatographic separation.