analytical chemistry Analytical skill, Analytical chemistry studies and uses instruments and methods to Separation process, separate, identify, and Quantification (science), quantify matter. In practice, separation, identification or quantification may constitute t ...

, ashing or ash content determination is the process of mineralization by complete

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion ...

for preconcentration of trace substances prior to a chemical analysis, such as

chromatography In chemical analysis, chromatography is a laboratory technique for the Separation process, separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it ...

, or optical analysis, such as

spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectro ...

Overview

The ash content of a sample is a measure of the amount of inorganic noncombustible material it contains. The residues after a sample is completely burnt - in contrast to the

ash Ash is the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash is the ...

remaining after incomplete combustion - typically consist of

oxide An oxide () is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of −2) of oxygen, an O2− ion with oxygen in the oxidation st ...

s of the inorganic elements present in the original sample. Ash is one of the components in the

proximate Proximates are used in the analysis of biological materials as a decomposition of a human-consumable good into its major constituents. They are a good approximation of the contents of packaged comestible goods and serve as a cost-effective and easy ...

analysis of biological materials, consisting mainly of salty, inorganic constituents. It includes metal

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

s which are important for processes requiring

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s such as Na⁺ (sodium), K⁺ (potassium), and Ca²⁺ (calcium). It also includes trace

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

s which are required for unique molecules, such as

chlorophyll Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy ...

and

hemoglobin Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobin ...

. Procedures for ash content determination are similar to procedures for

loss on ignition Loss on ignition (LOI) is a test used in inorganic analytical chemistry and soil science, particularly in the analysis of minerals and the chemical makeup of soil. It consists of strongly heating ( "igniting") a sample of the material at a specif ...

. Typically, the term ash is used for primarily organic material such as fuels and foodstuffs, while the term loss on ignition is used for primarily inorganic material such as rocks and combusted ash. A

crucible A crucible is a container in which metals or other substances may be melted or subjected to very high temperatures. Although crucibles have historically tended to be made out of clay, they can be made from any material that withstands temperat ...

can be used to determine the percentage of ash contained in a sample of material such as

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

, rubber, plastics, foodstuffs, or any burnable material. The appropriate method for ash determination varies depending upon the type of sample analyzed. Each method may vary in parameters such as furnace temperature, residence time in the furnace, number of heating steps, and sample preparation procedures. The

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

mandates ash content determination for most foodstuffs. Examples include *

ISO 2171 The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Mem ...

: ''Cereals, pulses and by-products — Determination of ash yield by incineration''; * ISO 3593: ''Starch — Determination of ash''; * ISO 928: ''Spices and condiments - Determination of total ash''; and * ISO 936: ''Meat and meat products - Determination of total ash''. Examples of ash content methods for the determination of ash in other solids include * ASTM D482: ''Standard Test Method for Ash from Petroleum Products''; * ISO 6245: ''Petroleum products — Determination of ash''; * ASTM D874: ''Standard Test Method for Sulfated Ash from Lubricating Oils and Additives''; * ASTM D3174: ''Standard Test Method for Ash in the Analysis Sample of Coal and Coke from Coal''; * ISO 1171: ''Solid mineral fuels — Determination of ash''; * ISO 18122: ''Solid biofuels — Determination of ash content''; * ASTM D1102: ''Standard Test Method for Ash in Wood''; * ASTM D2974: ''Standard Test Methods for Determining the Water (Moisture) Content, Ash Content, and Organic Material of Peat and Other Organic Soils''; * ASTM D2866: ''Standard Test Method for Total Ash Content of Activated Carbon''; * ISO 3451: ''Plastics — Determination of ash — Part 1: General methods''; * ASTM D2584: ''Standard Test Method for Ignition Loss of Cured Reinforced Resins''; and * ASTM D5630: ''Standard Test Method for Ash Content in Plastics''.

Fuels and consumption

Ashing is a test to deduce the amount of ash forming material present in a petroleum product so as to decide its use in certain applications. Ash-forming materials are considered to be undesirable impurities or contaminants. In the ash analysis of petroleum products, ash content represents the incombustible component remaining after a sample of the furnace oil is completely burned. The ash content of petroleum products is generally low. It is defined as the inorganic residue that remains after combustion of the oil in air at specific high temperature.

Ash Ash is the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash is the ...

typically ranges from 0.1 to 0.2% in oil. Some of the ash forming constituents occur naturally in crude oil; others are present as a result of refining or contamination during storage or distribution. Knowledge of the amount of ash-forming material present in a product can provide information as to whether or not the product is suitable application. In the ash analysis of coal and other solid fuels, the amount of sulfur retained in the ash during the ashing process is not constant, but rather is dependent upon the conditions of ashing as well as the other inorganic constituents in the ash that may form sulfates during the ashing procedure. As such, different ashing procedures may yield different ash contents.

Measurement

Apparatus

Some necessary apparatus include: * crucible (or similar porcelain or metal dishes) * muffled furnace *

hot plate A hot plate or hotplate is a heated flat surface on a stove or electric cooker on which food may be cooked, either built into an electric cooker or kitchen stove, or portable, plugged into an electric outlet. Hot plates can also be used as a h ...

* the sample

Procedure

A crucible and its lid are pre-weighed after thorough drying. The sample is added to the completely dry crucible and lid and together they are weighed to determine the mass of the sample by difference. The sample is placed in the hot furnace long enough so that complete combustion of the sample occurs. The crucible, lid and ash then are re-weighed.

Analysis

The analysis of

honey Honey is a sweet and viscous substance made by several species of bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of pl ...

shows: Typical honey analysis *

Fructose Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and gal ...

: 38% *

Glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...

: 31% *

Sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

: 1% *

Water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

: 17% * Other sugars: 9% (

maltose } Maltose ( or ), also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the tw ...

melezitose Melezitose, also spelled melicitose, is a nonreducing trisaccharide sugar that is produced by many plant sap eating insects, including aphids such as ''Cinara pilicornis'', by an enzyme reaction. This is beneficial to the insects, as it reduces th ...

) * Ash: 0.17% In this example the ash would include all the

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): M ...

in honey. Ashing is also performed prior to chemical analysis by inductively coupled plasma emission spectrometry.

References

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