Any combination of a cation associated with molecules or anions containing unshared pairs of electrons. The interaction can range from purely electrostatic to that approaching covalent character.

With respect to a complex we further define:

The term "complex" was found in the following pages:

Link database: US EPA Method 1636: Determination of hexavalent chromium by ion chromatography
Speciation analysis of rhenium by capillary electrophoresis-inductively coupled plasma mass spectrometry | EVISA's News
Instrument database: Shimadzu Europe - Nexera-e - Comprehensive Two-Dimensional Liquid Chromatograph
Instrument database: LLA Instruments GmbH - Echelle Spectra Analyzer ESA 3000
Instrument database: Dionex Corporation - ICS-5000 Capillary Reagent-Free IC System
Instrument database: GERSTEL GmbH & Co.KG - Automated Solid Phase Extraction (SPE)
Component database: PQ Systems - MEASUREspy SPC software
Instrument database: Applied Biosystems - 4700 Proteomics Discovery System
Instrument database: Waters Corporation - Quattro micro GC
Instrument database: HORIBA Jobin Yvon - ACTIVA-S
Instrument database: Thermo Finnigan - Surveyor Plus HPLC System
Instrument database: Analytik Jena AG - novAA® 400
Instrument database: Applied Biosystems - BIOiTRAQ™ TT System
Books and Special Issues on Elemental Speciation (published since 2006) | EVISA's News
Instrument database: Bruker Daltonics - micrOTOF - benchtop ESI-TOF MS
HPLC-ICPMS/MS as a versatile tool for the speciation of non-metals: Sulfur species in wine | EVISA's News
Species transformation during speciation analysis | EVISA's News
Instrument database: Bruker Daltonics - esquire4000
COST Action ES1205: Engineered nanomaterials from wastewater treatment & stormwatEr to Rivers | EVISA's Agenda of Events
Instrument database: Mercury Instruments GmbH - Process Analyzer PA-1