A solution that maintains constant  pH by resisting changes in pH from dilution or addition of small amounts of  acids and bases. 

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

Instrument database: Agilent Technologies Inc. - Capillary Electrophoresis System
Instrument database: Prince Technologies B.V. - PrinCE-C 650 and 660 Capillary Electrophoresis Systems
Speciation analysis of Gadolinium-based contrast agents using hydrophilic interaction liquid chromatography hyphenated with inductively coupled plasma-mass spectrometry by avoiding organic solvents | EVISA's News
Instrument database: Aurora Instruments Ltd. - Crysta 500 Water Purification System
Instrument database: SPEX CertiPrep - 2000 Geno/Grinder
Link database: US EPA Method 1636: Determination of hexavalent chromium by ion chromatography
Characterization and Speciation of Gold and Silver Nanoparticles by MEKC-ICP-MS | EVISA's News
Instrument database: LUMEX Ltd. - CAPELŪ-103R/103RT/104/104T/105
Instrument database: RECIPE Chemicals + Instruments GmbH - GP3000 Gradient HPLC Pump
Material database: Sigma-Aldrich - Auxiliary reagent for AAS: Cesium chloride Lanthanum chloride
Instrument database: RECIPE Chemicals + Instruments GmbH - IP3000 Isocratic HPLC Pump
Instrument database: Tecan - Columbus Microplate Washer
A highly selective and robust HPLC-ICP-MS arsenic speciation method for urine analysis | EVISA's News
Instrument database: Prince Technologies B.V. - PrinCE 700 Integrated Capillary Electro Chromatography system
Instrument database: Jasco Inc. - PU-2089 quaternary low pressure gradient pump
Instrument database: Alcott Chromatography Inc. - 765 HPLC Pump
Instrument database: Bruker Daltonics - esquire4000
Link database: EPA-ORD: Method 218.6: Hexavalent Chromium in Water by Ion Chromatography
Instrument database: Waters Corporation - 3100 Mass Detector
Instrument database: Teledyne CETAC Technologies - CEI-100 Capillary Electrophoresis Interface for ICP-MS