ChemSub Online: The Free Web Portal and Information System on Chemical Substances from around the World: Glossary and Acronyms - Letter H.
Provides information about:
- Chemical Inventories: Chemical inventory, AICS, DSL NDSL, EINECS, ELINCS, IECSC, NLP, NZIoC, TSCA.
- Registry Number, EC Number (EINECS, ELINCS, NLP), Chemical Name, Molecular Formula, Structure Formula.
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- REACH: REACH compliance, REACH & GHS, REACHsuite, EU REACH IT Solutions, IT solutions for managing REACH compliance.

- Chemical Super Lists and Inventories:
Chemical Carcinogenesis Research Information System (CCRIS),
European Inventory of Existing Commercial Chemical Substances (EINECS),
European List of Notified Chemical Substances (ELINCS),
Europan chemical Substances information System (ESIS),
Hazardous Substances Data Bank (HSDB),
High Volume Industrial Chemical List (HVICL),
HSNO Chemical Classification and Information Database (CCID),
Inventory of Existing Chemical Substances Produced or Imported in China (IECSC),
Toxic Substances Control Act (TSCA),
ChemBlink, EPA HPV Challenge, EPA HPVIS, EU HPV-LPV, HSNO CCID, TOXLINE.
- Chemicals and Chemistry: Formaldehyde, chemicals, chemical substances, chemistry, Baytouch Systems.
- GHS, Globally Harmonized System of Classification and Labelling of Chemicals, Global harmonisiertes System zur Einstufung und Kennzeichnung von Chemikalien, SGH, Système général harmonisé de classification et d'étiquetage des produits chimiques, 化学品分类及标记全球协调制度, 化学品の分類および表示に関する世界調和システム.
- InChI, InChIKey, MOSFIJXAXDLOML-UHFFFAOYSA-N, smiles, IUPAC Name.

ChemSub Online: The Free Web Portal and Information System on Chemical Substances from around the World: Glossary and Acronyms - Letter H.
Provides information about:
- Chemical analysis, Dedicated Analytical Solutions for chemical analysis from Foss, Brewing Lab Services, Siebel Institute Lab Services Brewing Analytical Testing.
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ChemSub Online: The Free Web Portal and Information System on Chemical Substances from around the World: Glossary and Acronyms - Letter H.
Provides information about:
- Återvinning symbol, алкохол, гераниол, деканол, етилов алкохол, натриев пропионат, пентанол.
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H:
Henry's law constant.

Henry's Law Constant is a measure of the tendency of a chemical to evaporate from a solution in water. It indicates whether a chemical accumulates in water or in air at equilibrium.
 
Half-life, t1/2:
Term used to characterise the rate of a first or pseudo-first order reaction. It is the time interval that corresponds to a concentration decrease by a factor 2. The half-life and the degradation rate constant are related by the equation t1/2 = -ln2/k. Half-lives are usually expressed in hours or days and can be assigned to either primary degradation or ultimate biodegradation (mineralisation).
 
HERO:
Highest Expected Regulatory Outcome.
 
HLB:
Hydrophylic-Lipophilic Balance.

The Hydrophilic-lipophilic balance of a surfactant (surface active agent) is a measure of the degree to which it is hydrophilic or lipophilic, determined by calculating values for the different regions of the molecule, as described by Griffin in 1949 and 1954. Other methods have been suggested, notably in 1957 by Davies.

Griffin's method for non-ionic surfactants as described in 1954 works as follows:
HLP =20*Mh/M
Where Mh is the molecular mass of the hydrophilic portion of the Molecule and M is the molecular mass of the whole molecule, giving a result on an arbitrary scale of 0 to 20. An HLB value of 0 corresponds to a completely hydrophobic molecule, and a value of 20 would correspond to a molecule made up completely of hydrophilic components.
The HLB value can be used to predict the surfactant properties of a molecule:
- A value from 3 to 6 indicates a W/O emulsifier
- A value from 7 to 9 indicates a wetting agent
- A value from 8 to 12 indicates an O/W emulsifier
- A value from 12 to 15 is typical of detergents
- A value of 15 to 20 indicates a solubiliser or hydrotrope.
Ref.: Griffin WC: "Classification of Surface-Active Agents by 'HLB,'" Journal of the Society of Cosmetic Chemists 1 (1949): 311.
Ref.: Griffin WC: "Calculation of HLB Values of Non-Ionic Surfactants," Journal of the Society of Cosmetic Chemists 5 (1954): 259

Davies' method in 1957 based on calculating a value based on the chemical groups of the molecule. The advantage of this method is that it takes into account the effect of strongly and less strongly hydrophilic groups.
The method works as follows:
HLB =7+m*Hh+n*Hl
Where m is the number of hydrophilic groups in the molecule, Hh is the value of the hydrophilic groups, n is the number of lipophilic groups in the molecule and Hl is the value of the lipophilic groups.
Ref.: Davies JT: "A quantitative kinetic theory of emulsion type, I. Physical chemistry of the emulsifying agent," Gas/Liquid and Liquid/Liquid Interface. Proceedings of the International Congress of Surface Activity (1957): 426-438.
 
HPLC:
High Performance Liquid Chromatography.

Is a form of column chromatography used frequently in biochemistry and analytical chemistry. It is sometimes referred to as high pressure liquid chromatography, although this terminology is considered out-of-date and disapproved by many. HPLC is used to separate components of a mixture by using a variety of chemical interactions between the substance being analyzed (analyte) and the chromatography column.
 
HPVC:
High Production Volume Chemical (EU).

A EU HPVC, is a chemical which is defined as being produced or imported in quantity of at least 1,000 tonnes per year in EU by at least one Industry.

The EU HPV-LPV Chemicals data is stored in the IUCLID (International Uniform Chemical Information Data Base).
 
HPV Programme:
High Production Volume Chemicals Programme (International).

The High Production Volume Chemicals Programme (HPV Programme) is an international programme which aims to assess the potential hazard of chemicals that are produced in high volumes. The OECD defines HPV as production or import of greater than 1,000 tonnes per year in at least one member country or in the European Union and assumes that high production is a proxy for high exposure. The OECD HPV Programme is supported by the ICCA (International Council of Chemical Associations) and is being carried out cooperatively by the chemical industry.

Various studies have found that insufficient data is available on the health effects of common chemicals[citation needed]. The US EPA found in a study before 1999 that of 2,800 chemicals investigated, 93% did not have sufficient data.

The US government defines high production volume chemicals as those organic non-polymer chemicals with greater than 1,000,000 pounds (450 t) production or import into the U.S.. These chemicals are required to have additional and highly detailed biological and environmental testing completed.
The US testing program was begun in 1999 and was expected to be completed in 2004.
 
HSDB:
Hazardous substance databank (U.S.).

HSDB is a toxicology data file on the National Library of Medicine's (NLM) Toxicology Data Network (TOXNET®).
It focuses on the toxicology of potentially hazardous chemicals. It is enhanced with information on human exposure, industrial hygiene, emergency handling procedures, environmental fate, regulatory requirements, and related areas. All data are referenced and derived from a core set of books, government documents, technical reports and selected primary journal literature.
HSDB is peer-reviewed by the Scientific Review Panel (SRP), a committee of experts in the major subject areas within the data bank's scope.
HSDB is organized into individual chemical records, and contains over 5,000 such records.
 
HSNO:
Hazardous Substances and New Organisms Act 1996 (New Zealand).

The passing of New Zealand’s Hazardous Substances and New Organisms Act (HSNO Act) in June 1996 represented one of the most significant reforms of environmental legislation since the Resource Management Act. The Act came into force in two stages. Provisions relating to new organisms took effect in July 1998. The provisions relating to hazardous substances came into force on 2 July 2001.

The Act established the Environmental Risk Management Authority (ERMA New Zealand) to assess and decide on applications to introduce hazardous substances or new organisms into New Zealand. This includes genetic modification of plants, animals and other living things in New Zealand.

More information can be found on the New Zealand's Environmental Protection Authority (EPA) web site: http://www.epa.govt.nz/.
 
HVIC:
High Volume Industrial Chemicals (Australia).
 
HVICL:
High Volume Industrial Chemicals List (Australia).

The National Industrial Chemicals Notification and Assessment Scheme (NICNAS) has compiled a list of industrial chemicals that are manufactured and imported in Australia in large quantities based on the information supplied by companies during 2001 and 2002. An industrial chemical is any chemical that has an industrial use, whether or not it also has an excluded use, with excluded use meaning agricultural, veterinary or pharmaceutical use or use as, or in, food. Only the quantity of the chemical used for 'industrial' purposes was reportable. A number of industrial chemical categories were exempt from reporting. These included articles, radioactive materials, incidentally produced chemicals, naturally occurring chemicals and polymers.

Companies were required to report industrial chemicals they imported or manufactured in quantities of 100 tonnes or more per year. Importers were required to report chemicals imported in products/mixtures, whose combined quantity across all products was 100 tonnes or more per year.

Only those chemicals with a combined import and manufacturing quantity of 1000 tonnes or more have been included in the Australian HVICL. The HVICL contains aggregate quantities of reportable chemicals and their use and industry categories in bands defined by orders of magnitude, namely, 1000-9999 tonnes, 10,000-99,999 tonnes, 100,000-999,999 tonnes, and 1,000,000 tonnes and above.

In a few instances, confidentiality has been granted for certain information supplied on a chemical, such as CAS No, chemical name, use and/or industry category.

More information can be found on the NICNAS web site: https://www.nicnas.gov.au/.
 
Hydrolysis:
Decomposition or degradation of a chemical by reaction with water.
 
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