in Glossary


Acid, acidic

A substance containing hydrogen which, when dissolved in water, produces hydrogen ions such that the Ph is less than 7; any solution containing an acid and with a pH<7. Opposite of Basic.

Alkali, alkaline

Alternate names for base or basic, or having a Ph greater than 7. See also Base.


A unit of measurement in science for small objects; one Angstrom is 10-10 meter, or 100 picometers, or 0.1 nanometers. See our helpful chart on size, weight and concentration at the nanoscale.


A negatively charged ion. Opposite of Cation.


In an electrochemical cell, the electrode at which oxidation occurs (the loss of an electron). Opposite of Cathode.


An atom is one of the basic units of matter. Atoms form the building blocks of the simplest substances called chemical elements. Atoms vary greatly in weight, but they are all about the same size, ranging from 0.3 to 3 angstroms. For example, an atom of plutonium, one of the heaviest elements, weighs more than 200 times as much as an atom of hydrogen, the lightest element. Yet the diameter of a plutonium atom is about 151 picometers, only about three times that of a hydrogen atom, which is about 53 picometers.

Atomic Absorption Spectrometry (using flame Atomic Absorption Spectrometer)

A technique of analytical chemistry where a solution containing a metal ion and/or suspension is aspirated into a high temperature flame. The resulting atoms absorb light emitted from a lamp of a wavelength specific for each metal. The amount of light absorbed is a quantitative measure of the concentration of metal in the solution. See also Mass Spectrometry.

Atomic Cluster (Atomic Quantum Cluster)

This term is used for sub-nanometer (< 1nm) sized substances or structures. In chemistry, a cluster is an ensemble or group of bound atoms intermediate in size between a molecule and a bulk solid where elements vary in the expression of their intensive properties. Transition metals, such as silver, form especially robust clusters. The term cluster was coined by F.A. Cotton in the early 1960s to refer to compounds containing metal-to-metal bonds. In another definition, a cluster compound contains a group of two or more metal atoms where direct and substantial metal-to-metal bonding is present. The prefix ‘nuclear’ is used to identify elemental combinations, for example ‘heteronuclear’ means there are two different elements and ‘polynuclear’ would mean there are three or more different elements within the cluster. Since intensive properties can change as size decreases, pico-scale silver clusters initiate quantum effects and become exponentially efficient as catalysts and as sources of silver ions (Ag+) for reactions.

Agency for Toxic Substances and Disease Registry (ATSDR)

A federal public health agency of the U.S. Department of Health and Human Services which serves the public by analyzing research and taking responsive public health actions, providing trusted health information to prevent harmful exposures and diseases related to toxic substances.


Base, basic

A substance which, when dissolved in water, produces OH- ions and leads to a Ph greater than 7. A solution containing a base and having a pH>7. Opposite of Acidic.


Having an effect on or causing a [positive] reaction in living tissue.



An organic compound used it kill or control insects (a pesticide), derived from carbamic acid (NH2COOH). Carbamate esters are also called urethanes.


A positively charged ion. Opposite of Anion.


In an electrochemical cell, the electrode at which reduction takes place, or an electron is gained. Opposite of Anode.

Charge (electric)

An intrinsic characteristic of elementary particles that determines their electromagnetic interactions. The physical property of matter that causes it to experience a force when in an electromagnetic field. Charge can also refer to an amount of electrons and can be measured in coulombs(C).

Claim or Health Claim

Statements of cause and effect between ingesting or otherwise taking a substance (i.e. a drug or compound) and it producing an effect claimed to treat, prevent, cure or mitigate a disease state.

Claimed PPM

The concentration (of silver) reported on the label of a product in parts per million (PPM).


Particles with a small number of atoms (≤150) are sometimes referred to as clusters, or Atomic or Quantum Clusters.

Colloid, Colloidal / Colloidal dispersion, suspension

A colloidal suspension consists of two separate phases – a dispersed phase and a continuous phase; the dispersed phase is made of particles or droplets, which are suspended and distributed evenly throughout the continuous phase; a suspension of solid particles of the proper size range to be a colloid (typically between 1 to 10,000 nm) in a continuous (liquid) phase; a liquid mixture in which solid particles within a colloidal range are dispersed.

Colloidal silver

A water-based suspension of silver particles or colloids. A heterogeneous mixture composed of two or more substances with one substance being silver, wherein each keeps its original properties and the solute-like, suspended solid particles remain dispersed within a liquid without settling. With elemental silver or a silver compound, particles may be neutral chunks of silver or they may be coated on the surface with molecules that carry an active electrical charge.

Colloidal stability

A description of the degree to which a suspension of particle remains stable, meaning the suspended matter does not fall out of suspension, or precipitate.

Complementary & Alternative Medicine (CAM) / Alternative Medicine

The terms “complementary medicine” or “alternative medicine” are used inter-changeably with traditional medicine in some countries. They refer to a broad set of health care practices that are not part of that country’s own tradition and are not integrated into the dominant health care system. See also Medicine, Traditional Medicine.


A substance formed when two or more chemical elements are chemically bonded together. Two types of chemical bonds common in compounds are covalent bonds and Ionic bonds. The elements in any compound are always present in fixed ratios. In silver, compounds are common and their properties are known, and generally possess a higher toxicity index.


The amount of a substance per defined space or volume. Concentration usually is expressed in terms of mass per unit of volume. The mass of a constituent divided by the volume of the mixture. See our helpful chart on size, weight and concentration at the nanoscale.


A measure of the ability of electricity to flow through a material; the ability or power to conduct or transmit heat, electricity, or sound. It is measured in Siemens or microsiemens per meter [S/m]. Opposite of Resistivity, or Resistance. A TDS meter will measure conductivity, and is commonly misused to measure concentration of homemade colloidal silver preparations.


A unit of charge. 1 coulomb represents 1 amp flowing for 1 second. Coulombs can be used to calculate rate(s) of reaction, especially in electrochemical cells.

Covalent bonds

Chemical bonds formed by sharing of electrons.


De-ionized (or deionized) water

Ultrapure water from which dissolved solids and ionic content have been largely removed, often cations like sodium, calcium, iron, and copper, and anions such as chloride and sulfate. A complete de-ionized water system includes ultrafiltration and other methods to ensure the water conforms to specifications that include absence of microbial content and organic materials, as well as certain Conductivity requirements.

Dielectric constant

The ability of a non-conducting material to reduce the electrical interaction between two electrical charges. Water has a high dielectric constant. Also known as relative permittivity.


The bending of waves, especially sound and light waves, around obstacles in their path. It is detectable in light waves by the presence of a pattern of closely spaced dark and light bands (diffraction pattern) at the edge of a shadow, and is a technique employed in elemental analysis.

Dietary Supplement

A product intended for oral consumption intended to provide nutrients in order to aid in supplementing the diet, as regulated by the Food & Drug Administration, under the Dietary Health And Education Action (DHSEA) of 1994.

Dose (Dosage)

A quantity of a medicine, drug, supplement or other substance recommended to take at a particular time.


A medicine or other substance that produces a physiological effect when ingested or is otherwise introduced into the body.

DSHEA (Dietary Supplement Health Education Act)

Groundbreaking legislation in 1994 resulting from consumers demanding their right to safe natural remedies and traditional medicines, which were allowed to remain on the market, but without making specific health claims. How Dietary Supplements Are Regulated in the USA, or visit the FDA web site.

Dynamic Light Scattering ( also Photon Correlation Spectroscopy)

This technique is one of the most popular methods used to determine the size of particles. Shining a monochromatic light beam, such as a laser, onto a solution with spherical particles in Brownian motion causes a Doppler Shift when the light hits the moving particle, changing the wavelength of the incoming light. This change is related to the size of the particle. It is possible to compute the sphere size distribution and give a description of the particle’s motion in the medium, measuring the diffusion coefficient of the particle and using the autocorrelation function.



A conductor used to establish electrical contact with a nonmetallic part of a circuit.


The producing of chemical changes by passage of an electric current through a solution.


A toxic heat-stable lipopolysaccharide substance present in the outer membrane of gram-negative bacteria that is released from the cell upon lysis. Some medicinal products are tested for the absence of these in order to ensure purity and absence of microbial contamination.


A fundamental, subatomic particle with a negative charge.


The amount of heat liberated or absorbed when a chemical reaction is carried out at constant pressure.


A quantitative representation of the extent of disorder of a system. A gas will have greater entropy than the same quantity of a solid or liquid.

Environmental Protection Agency (EPA)

An agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress.



In colloid chemistry, flocculation refers to the process by which fine particulates are caused to clump together into a floc. The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid.


Good Lab Practices (GLP)

The OECD Principles of Good Laboratory Practice (GLP) ensure the generation of high quality and reliable test data related to the safety of industrial chemical substances and preparations. The principles have been created in the context of harmonizing testing procedures for the Mutual Acceptance of Data (MAD), which intends to prevent the same chemicals from having to be tested repeatedly in different jurisdictions.

Good Manufacturing Practices (GMP)

Good manufacturing practices are guidelines that provide a system of processes, procedures and documentation to assure a product has the identity, strength, composition, quality and purity that appear on its label. These GMP requirements are listed in Section 8 of NSF/ANSI 173 which is the only accredited American National Standard in the dietary supplement industry developed in accordance with the FDA’s 21 CFR part 111. NSF International’s GMP Registration Program enables manufacturers to become independently registered by NSF to meet GMP requirements.


(Generally Recognized As Safe): Under the Federal Food, Drug, and Cosmetic Act, any chemical or substance that is intentionally added to food or as a food additive that is generally recognized, among qualified experts, as having been adequately shown to be safe under the conditions of its intended use.



A colloid system wherein the colloid particles are hydrophilic and dispersed in water.


Either inorganic suspensions or organic suspensions (herbal distillates) stabilized by water as the continuous phase. In the case of silver hydrosol, it is a mixture of silver ions and silver nanoclusters.

Homoeopathic Pharmacopoeia Convention of the United States (HPCUS)

The HPCUS produces the Homeopathic Pharmacopoeia of the United States (HPUS), which is recognized in the Federal Food, Drug, and Cosmetic Act (FDCA) as an official compendium within the meaning of the statute

Homeopathy, Homeopathic Medicine

The practice of medicine that embraces a holistic, natural approach to the treatment of the sick, which treats the person as a whole, rather than focusing on a diseased part. Homeopathy is produced according to the U.S. FDA-recognized Homeopathic Pharmacopoeia of the United States from natural sources, whether vegetable, mineral, or animal in nature. The guiding principle of Homeopathy is “let likes cure likes,” similia similibus curentur. While the concept dates back to Greek Father of Medicine, Hippocrates (460-377 B.C.), it was German physician Dr. C. F. Samuel Hahnemann (1755-1843) who first codified this principle into a system of medicine. Over the years, by means of provings, toxicological data, and clinical experience, the homeopathic drug pictures of over 2000 substances have been derived.


See Lyophillic.


See Lyophobic.


Inductively Coupled Plasma (ICP) Mass Spectrometry

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is capable of detecting metals and several non-metals at concentrations as low as parts-per-trillion. This highly specialized technology is used in advanced laboratories to measure concentrations at below what are considered contaminant levels. New optics systems result in a low random background and high sensitivity, making analysis down to the sub-nanogram-per-liter level feasible. See also Mass Spectrometry.


Relating to or denoting chemical compounds that do not contain carbon (excluding carbonates, bicarbonates, cyanides, and carbides).


An atom or molecule having a net electrical charge. The Handbook of Chemistry and Physics, 91st edition (2010-2011) defines an ion as an atomic or molecular particle having a net electrical charge. An electrical charge may be expressed either as positive or negative. When large structures carry a net electrical charge, such as a protein, a macromolecule or a nanoparticulate cluster, the term “charged particle” distinguishes such a complex unit from common, small ionized atoms or small molecules.

Ionization (ion formation; ionize)

The phenomenon of ionization is a physical dissociation process during which a compound interacts with a solvent and then ions form of opposing electric charge. When ionic substances dissolve, their ions are surrounded by solvent molecules (e.g., water) and are physically separated from each other. Ionization converts an Atom or molecule into an ion by changing the number of orbiting electrons versus the number of core protons. This process works differently depending on whether an ion with a positive or a negative electric charge is being produced. A positive electric charge is produced when an electron bond to an Atom or molecule absorbs enough energy from an external source to escape from the electric potential barrier that originally confined it – the amount of energy required is called the ionization potential. A negative electric charge is produced when a free electron collides with a receptive electron cloud of another atom and is subsequently caught inside its electric potential barrier, releasing any excess energy.

ion-selective electrode (ISE) (also specific ion electrode or SIE)

Is a transducer (or sensor) that converts the activity or effective Concentration of a specific ion dissolved in a solution into an electrical potential, which can be measured by a voltmeter or pH meter. The voltage is dependent on the logarithm of the ionic activity, according to the Nernst equation.

Ionic bond

A chemical bond formed by the attraction of negative and positive ions; chemical bonding resulting from the transfer of one or more electrons from one atom or a group of atoms to another.

Ionic Compounds

Compounds containing atoms associated predominantly with ionic bonding; an electrically neutral combination of ions. Examples include table salt (NaCl), which is composed of positively charged sodium ions and negatively charged chloride ions. Another example is silver nitrate (AgNO3), composed of positive silver ions and negative nitrate ions.


The International Union of Pure and Applied Chemistry is an international federation of National Adhering Organizations that represents chemists in individual countries, and works to advance chemical sciences and contribute to the application of chemistry in the service of Humankind. The chemical nomenclature they have developed is used most frequently worldwide in science.


Jarish-Herxheimer Reaction

An immune-clearing event in which an individual may feel worse as large amounts of toxins clear from the body (“die-off”).



LD50/Lethal Dose

By definition, LD50 means the dose (quantity) of a chemical, which has been calculated to cause death in 50% of a defined experimental animal population. See also NOAEL.


Literally “solvent loving”. The situation where the dispersed phase in a suspension have a very strong affinity for the continuous phase. In water based suspensions also called Hydrophilic. All ions have a strong affinity for water and are thus lyophilic.


Literally “solvent fearing”. The situation where the dispersed phase in a suspension such as silver metal particles have no affinity for the continuous phase. In water based suspensions also called Hydrophobic.


Mass Spectrometry

Mass spectrometry is an analytical chemistry technique that measures the mass-to-charge ratio and abundance of gas-phase ions. A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio. MS is use to identify the chemical constitution of a substance by means of the separation of gaseous ions, according to their differing mass and charge. See also Spectroscopy.

Medicine (see also Homeopathic Medicine)

The science or practice of the diagnosis, treatment, and prevention of disease (in technical use often taken to exclude surgery); per regulations, a medicine is a Compound or preparation used for the treatment or prevention of disease, especially a drug or drugs taken by mouth, meaning a supplement may not make such claims. See also Complimentary and Alternative Medicine, Traditional Medicine.

Monographs or Drug Monographs

Drug monographs provide descriptions of medicinal preparations, specifying the types and quantities of ingredients in a drug or class of drugs, directions and conditions for use of the drug, and any known contraindications.



A prefix with the meaning “very small, minute,” used in the formation of Compound words (e.g., nanogram or nanoparticle); in the names of units of measure, it has the specific sense one billionth (10-9). For example, one nanometer is one-billionth of a meter.


Abbrev nm; one billionth of a meter (10-9), or 0.001 microns; in relative terms, a human hair is generally 50,000-100,000 nm in diameter. See our helpful chart on size, weight and Concentration at the nanoscale.


Although no standard definition is as yet universally adopted, generally a microscopic particle having at least one dimension less than 100 nm. Many definitions also define nanotechnology and thus nanoparticles to include materials in this small size range which also have new properties compared to larger sizes of the same material. In nanotechnology, a particle is defined as a small object which behaves as a whole unit with respect to its transport and properties. Spherical particles are further classified according to diameter. It is important to understand that diameter size may or may not affect intensive properties. A man-made scale of 1nm to 100nm does not create a meaningful range if there is no change in properties or behavior. For example, a 100 nm-sized particle may have the same properties as a 1,000 nm-sized particle, and a 101 nm-sized particle may have exactly the same transport characteristics and properties as it has at 80 nm. In general, when considering objects at or smaller than 100 nm, the smaller a particle, the greater the probability there will be a change in properties. See also Particle.


The science of manipulating materials on an atomic or molecular scale especially to build microscopic devices (Merriam Webster, Encyclopedia Britannica, 2014). The National Nanotechnology Initiative defines nanotechnology in the following way: “Nanotechnology is the understanding and control of matter at the nanoscale, at dimensions between approximately 1 and 100 nanometers, where unique phenomena enable novel applications.”

New Dietary Ingredients (NDI)

A new dietary ingredient, as defined by the FDA in effort to regulate new supplements, is a dietary ingredient that was not sold in the United States in the form of a dietary supplement before October 15, 1994 (pre-DSHEA). The U.S. Food and Drug Administration (FDA) requires specific safety information from a manufacturer intending to market a dietary supplement containing a new dietary ingredient. This information is not required for older dietary supplement ingredients. Learn more.

NOAEL (No-Observed Adverse Effect Level)

The highest exposure level at which there are no biologically significant increases in the frequency or severity of adverse effect between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered adverse or precursors of adverse effects.



The basic unit of electrical resistance equal to one volt divided by one ampere, often usd to measure conductivity. The Conductivity is proportional to the reciprocal of its resistance.


(Greek: oligos = few, dynamis = force) the great power exerted by certain metals in low concentration, an effect discovered by Swiss Botanist Karl Wilhelm von Nägeli in 1893.


A route of administration meaning to be taken by mouth.

Organic, Organic molecule

Substance whose molecules contain one or more carbon atoms (often many more than one, but excluding carbonates, bicarbonates, cyanides, carbides, and a few others). Until 1828, scientists believed organic compounds could be formed only by life processes. Carbon is more likely to form molecular chains and rings than elements do, so its compounds are vastly better known than all others.


The loss of electrons by an Atom or molecule; the gaining of oxygen by a substance and the resulting chemical effect and/or surface changes. Opposite of Reduction.


The prescription or use of a drug or other product other than that for which it has been officially indicated or approved.



In the physical sciences, a particle is a small localized object to which can be ascribed several physical or chemical properties such as volume or mass. The word particle is generic; no specific size is implied by the term. A particle should contain more than two atoms because the very well characterized mercury (I) species Hg22+ is always referred to as an ion by chemists and thus establishes a precedent. See also Nanoparticle.

Particle size

An idealized concept that assumes all particles in a suspension have the same geometric shape, and usually assumed to be spherical; the size of any given particles as determined by its diameter. Multiple methods exist to measure particle size, especially in the nanoscale, and these include Electron Microscopy, Dynamic Light Scattering, among others.

Parts per Million (PPM)

A unit of concentration, usually abbreviated; a way to quantify very low concentrations of substances. For example, 1 ppm is equivalent to 1 milligram per liter (abbreviated as mg/L), or 0.0001% concentration. Parts per Billion (PPB) and Parts per Trillion (PPT) are also commonly used to indicate and even lower concentrations. See our helpful chart on size, weight and Concentration at the nanoscale.


A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, fungicides, and various other substances used to control pests. Under United States law, a pesticide is also any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant. Pesticides are now ubiquitous in most parts of the world, and water supplies.


In chemistry, a measure of the acidity or basicity of an aqueous solution, or of the molar Concentration of hydrogen ions in solution. Solutions less than pH 7 are called acidic, and those greater than pH 7 are basic or alkaline. Pure water has a pH very close to 7. Acidic and basic are two extremes that describe chemicals, just like hot and cold describe extreme temperatures. Mixing acids and bases can cancel out their extreme effects; much like mixing hot and cold water. A substance that is neither acidic nor basic is neutral. The pH scale ranges from 0 to 14. Each whole pH value is ten times stronger than the preceding value. For example, a pH of 4 is ten times more acidic than a pH of 5 and 100 times (10 times 10) more acidic than a pH of 6.


A publication which contains directions for identifying Compound medicines, usually published by a government agency, or by a medical or pharmaceutical society.

Pharmaceutical Grade Purified Water

Ultra-pure water which has been filtered to USP 23 or USP 24 level of purity. Because the absence of microbiological content is of importance, the water must be monitored and tested regularly to ensure it remains within industry limits.


One trillionth of a meter (1 pm=10-12 m), or 0.001nm. See our helpful chart on size, weight and Concentration at the nanoscale.


To fall out of suspension; the instability of a suspension.


A substance, typically produced by a bacterium, that produces fever when introduced or released into the blood


Quantum mechanics

A branch of physics that deals with the structure and behavior of very small pieces of matter; it is a theory of matter that is based on the concept of the possession of wave properties by elementary particles.


Recommended Daily Allowance (RDA)

The estimated amount of a nutrient (or calories) per day considered necessary for the maintenance of good health by the Food and Nutrition Board of the National Research Council/ National Academy of Sciences.


The gain of electrons by an Atom or molecule; the loss of oxygen by an element. Opposite of Oxidation.

Reference Dose (RfD)

The RfD is a numerical estimate of a daily oral exposure to the human population, including sensitive subgroups such as children, that is not likely to cause harmful effects during a lifetime. Learn more here.


Legal mandates established by governmental or inter-governmental agencies used to control how entities operate or transact.


A measure of how strongly a material opposes the flow of electrical current. A low resistivity indicates a material that readily allows the movement of electric charge. The SI unit of electrical resistivity is the ohm meter [Ω m]. Opposite of Conductivity.



An ionic Compound formed by the reaction of an acid and a base. The products of the reaction of an acid and a base are a salt and water. For example, the base AgOH reacts with the acid HNO3 to form the salt AgNO3 and water; A chemical Compound consisting of an assembly of cations [+] and anions [-]; compounds with ionic chemical bonds. In solution, salts may be neutral, weakly acidic or weakly alkaline. The Handbook of Chemistry and Physics, 91st edition (2010-2011) defines a salt as an ionic Compound formed by the reaction of an acid and a base. In chemistry, such reactions are real or they are hypothetical. For example, a real salt producing chemical reaction occurs when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), a base, resulting in the formation of sodium chloride (NaCl) or table salt. As another example, when hydrochloric acid (HCl) reacts with ammonium hydroxide (NH4OH), a base, a salt called ammonium chloride (NH4Cl) forms. However, this is reaction is hypothetical because the chemical species called ammonium hydroxide does not actually exist as a stable entity.

Siemens (SI unit symbol: S)

The unit of electric conductance and electric admittance in the International System of Units (SI). Conductance and admittance are the reciprocals of resistance and impedance respectively, hence one siemens is equal to the reciprocal of one ohm.

Silver salt

Silver salts are either mineral salts or organic salt compounds. Simple mineral salts of silver include silver sulfide, silver fluoride, silver chloride, silver bromide, silver iodide etc. Complex mineral salts of silver would include silver nitrate, silver nitrite, silver sulfate, silver phosphate Organic silver salts would include silver acetate, silver aspartate, silver sulfadiazine [C10H9AgN4O2S], etc.  Some silver salts, such as silver nitrate, can rapidly denature proteins. Silver salts deposited in the body can experience UV-light reactions within the skin or eyes manifesting as argyria or argyosis. These reactions occur when the liver becomes incapable of eliminating the silver via the normal excretory pathways, typically from intentional overexposure of silver far beyond the EPA Reference Dose. In medicine, silver nitrate salt sticks or silver acetate solutions are used to cauterize superficial vessels in the nose to stop repetitious nosebleeds; silver sulfadiazine is commonly used to treat moderate and severe burns or chronic, non-healing skin lesions. Silver nitrate drops have historically been used in newborn eyes to prevent pathogenic blindness.


A fluid colloidal system of two or more components, e.g. a protein sol, a gold sol, an emulsion, a surfactant solution above the critical micelle concentration; a suspension of metallic particles less than 1 micron and usually less than 100 nm in diameter in a continuous liquid phase, usually a water phase.


In chemistry, homogeneous mixture of two or more substances. The dissolving medium is called the solvent, and the dissolved material is called the solute. A solution is distinct from a colloid or a suspension.


A term used to describe a general classification of a suspension, in our case, of various silver suspensions or solutions, each defined by different physical and/or chemical properties.


The study of the interaction between matter and radiated energy. Spectroscopic data is often represented by a spectrum, a plot of the response of interest as a function of wavelength or frequency. This method is frequently used in elemental analysis. See also Mass Spectrometry.


Resistance or the degree of resistance to chemical or physical change or disintegration over time.

Surface area

The total area of the surface of a three-dimensional object; an idealized concept which assumes all particles in a suspension have the same geometric shape, usually assumed to be spherical. The surface area can then be calculated from this geometric model.


The state in which the particles of a substance are mixed with a fluid but are undissolved.


Thermodynamics (chemical)

The study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics.


A route of administration meaning to be applied to the skin or body’s surface area, with penetrating any cavity.

Total Dissolved Solids (TDS)

A measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a filter with two-micron (2,000nm or 0.002mm) pores. [NOTE: a TDS Meter is not an accurate way to measure the Concentration of silver colloids. For more, see our FAQs .]


The degree to which a substance can harm humans or animals. Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure, sometimes lasting for the entire life of the exposed organism.

Traditional Medicine

The sum total of the knowledge, skills, and practices based on the theories, beliefs, and experiences indigenous to different cultures, whether explicable or not, used in the maintenance of health as well as in the prevention, diagnosis, improvement or treatment of physical and mental illness. See also Medicine, Complimentary and Alternative Medicine.

Transmission electron microscopy (TEM)

A microscopy technique in which a beam of electrons is transmitted through an ultra-thin specimen, interacting with the specimen as it passes through. An image is formed from the interaction of the electrons transmitted through the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film, or to be detected by a sensor such as a CCD camera. A TEM is a practical application of wave-particle duality since electrons, usually considered particles, are used as light waves to form images. A TEM can provide upwards of 5,000,000 times magnification, and give visibility almost down to the nuclear level.

Tyndall Effect

The scattering of light by dispersed colloidal particles or emulsion suspensions, named after the Irish scientist John Tyndall. The suspended particles reflect the light, making a beam of lighting passing through it more visible. This effect can be used to determine whether a colloid has large particles or not. The Tyndall effect is noticeable when car headlights are used in fog and the light beams are visible versus in clear weather the light beams are invisible. The finer or smaller the dispersed particles, the smaller the diameter cone of light beam scatter.


Ultraviolet-Visible Spectroscopy / UV-Vis Spectrometer

Refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent (near-UV and near-infrared (NIR)) ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, molecules undergo electronic transitions.

United States Pharmacopeia (USP)

The official pharmacopeia of the United States, published dually with the National Formulary as the USP-NF. Prescription and over-the-counter medicines and other health care products sold in the United States are required to follow the standards in the USP-NF. USP also sets standards for food ingredients and dietary supplements.

USDA (US Department of Agriculture)

Federal agency that develops and executes policy on farming, agriculture, forestry and food. USDA has jurisdiction over dietary supplements because people ingest supplements, and therefore places where they are manufactured are considered food facilities, and must follow the guidelines set forth by the USDA and others.



See our helpful chart on size, weight and Concentration at the nanoscale.


Water: de-ionized

Water which has been purified by treating with mixed bed ion exchange resins which convert the ions into water. One of the highest degrees of purity achievable for water is pharmaceutical grade purified water meeting USP 23/24 standard (See also Water for injection below)

Water: distilled

Water purified by boiling and condensing the resultant steam.

Water: filtered

Water purified by passing through one or more filters, designed to remove basic contaminants.

Water: reverse osmosis

Water which has been purified by force through a membrane, resulting in virtually pure water.

Water for injection

Water that has been purified by distillation for the preparation of products for intravenous use. One of the highest degrees of purity achievable for water. Also known as USP 24 Grade Water, or Pharmaceutical Grade Purified Water.

Wave-particle duality

Postulates that all particles exhibit both wave and particle properties. A central concept of quantum mechanics, this duality addresses the inability of classical concepts like “particle” and “wave” to fully describe the behavior of quantum-scale objects.


See our helpful chart on size, weight and Concentration at the nanoscale.



Zeta-potential or electrokinetic potential (ζ-potential)

The potential produced by the effective charge of a particle, measured at the boundary between what is moving in a solution with the particle and the rest of the solution; the electric potential across all phase boundaries between solids and liquids; in colloids, the zeta potential is the potential across the ionized layer around a charged colloidal particle which organizes water molecules in the liquid phase. Neutralizing this potential may cause a colloid to aggregate and precipitate, and so affects product stability.

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