Analytical Reference Glossary

Heated Persulfate Oxidation A wet chemical TOC oxidation method in which sodium persulfate is decomposed at elevated temperature (typically 95–100 °C) to generate sulphate radical anions that convert organic carbon to CO₂. The oxidation principle used by the Aurora 1030W TOC Analyser. High-Temperature Combustion (TOC) A TOC analysis method in which the sample is injected into a catalytic combustion furnace operating at 680 to 1,200 °C, converting all organic and inorganic carbon to CO₂ for NDIR detection. Provides the most complete oxidation of any TOC method, including refractory organic compounds. Potentiometric Titration A titration in which the endpoint is found by monitoring the electrical potential of an indicator electrode against a reference electrode as titrant is added, rather than by a colour-change indicator. It is the basis of the modern automatic titrator (autotitrator). NDIR Detection (TOC) Non-Dispersive Infrared detection — the measurement step in virtually all modern TOC analysers, in which CO₂ produced by sample oxidation is quantified by its absorption of infrared radiation at 4.26 µm. Provides high specificity for CO₂, fast response, and a wide linear range. UV-Persulfate Oxidation A wet chemical TOC oxidation method in which ultraviolet irradiation generates sulfate radical anions from sodium persulfate at or near ambient temperature. Widely used for clean water matrices including drinking water, pharmaceutical water, and ultrapure water.

Dissolved Organic Carbon (DOC) The fraction of total organic carbon (TOC) that passes through a 0.45 µm membrane filter. DOC excludes particulate organic matter such as algae, bacteria, and suspended particles, and is the most commonly reported organic carbon parameter in drinking water and environmental monitoring. NPOC (Non-Purgeable Organic Carbon) Non-Purgeable Organic Carbon — the fraction of total organic carbon that remains in a water sample after acidification and inert-gas sparging to remove dissolved inorganic carbon and volatile organics. The most widely used measurement mode for drinking water, environmental, and pharmaceutical TOC analysis. Total Organic Carbon The mass concentration of carbon bound in organic compounds in a water sample, expressed in mg/L. A key bulk water quality parameter used in environmental monitoring, drinking water compliance, and industrial process control.

Cyanide Distillation A sample preparation step in total cyanide analysis where strong acid, heat, and UV irradiation are used to break down all cyanide-containing species — including stable iron-cyanide complexes — and collect the liberated HCN gas for measurement. Free Cyanide The sum of the cyanide ion (CN⁻) and hydrogen cyanide (HCN) in solution. The most acutely toxic and biologically available form of cyanide, and a subset of WAD cyanide. ICMC (International Cyanide Management Code) A voluntary, performance-driven certification programme for the safe production, transport, and use of cyanide in gold and silver mining. Signatory operations are audited against the Code, whose environmental requirements are framed in WAD cyanide terms. Total Cyanide The comprehensive measure of all cyanide-containing species in a sample, including free cyanide, WAD-range metal complexes, and the stable iron-cyanide complexes that survive weak acid conditions. WAD Cyanide The fraction of cyanide in solution that dissociates under weak acid conditions (pH 4.5), releasing hydrogen cyanide gas. Includes free cyanide and labile metal-cyanide complexes, but excludes stable iron-cyanide species.

Continuous Flow Analysis The family of automated wet chemistry techniques in which sample and reagents are continuously pumped through tubing and a detector while moving. Includes both Segmented Flow Analysis (SFA) and Flow Injection Analysis (FIA). Flow Injection Analysis A continuous-flow technique in which a precisely timed sample plug is injected into a flowing reagent stream. No air segmentation is used; reproducible results depend on controlled dispersion and precise timing. Segmented Flow Analysis An automated continuous-flow technique in which air bubbles regularly segment the liquid stream, preventing carryover between samples and enabling high-throughput batch analysis.

Gavage Needle Gauge The standardised measure of a gavage (feeding) needle's outer diameter, where a lower gauge number means a larger diameter. Gauge is selected by species and body weight: typically 20 to 24 gauge for mice and 16 to 18 gauge for rats. Intraperitoneal Injection Delivery of a substance into the peritoneal cavity of a rodent via a needle inserted through the lower abdominal wall. A common route for anaesthetic agents, pharmacological compounds, and large-volume doses that cannot be given intravenously. Oral Gavage Dose Volume The volume of liquid administered to a laboratory animal in a single oral gavage, expressed relative to body weight. The widely used good-practice volume for both mice and rats is 10 mL/kg body weight, with lower volumes preferred wherever the dose formulation allows. Oral Gavage A technique for delivering precise volumes of liquid substances directly to the stomach of laboratory animals via a feeding needle or flexible catheter passed through the mouth and oesophagus. The standard method for oral dosing in preclinical pharmacokinetic, toxicology, and nutritional studies. Subcutaneous Injection Delivery of a substance into the subcutaneous space — the layer of loose connective tissue directly beneath the skin — of a laboratory animal. The simplest and least stressful injection route in rodents, used for slow-release formulations, vaccines, and compounds requiring gradual systemic absorption. Tail Vein Injection Intravenous administration of compounds directly into the lateral tail vein of mice or rats. The standard route for IV dosing in rodent studies, including pharmacokinetic experiments, cell delivery, and viral vector administration.