Category Archives: Photo
Finding the Optimum Response Using a Searching Algorithm
If we know the equation for a response surface, then it is relatively easy to find the optimum response. Unfortunately, we rarely know any useful details about the response surface. Instead, we must determine the response surface’s shape and locate … Continue reading
Instrumentation for Flow Injection Analysis
The basic components of a flow injection analyzer are shown below and include a pump for propelling the carrier stream and reagent streams, a means for injecting the sample into the carrier stream, and a detector for monitoring the composition … Continue reading
Ion-Exchange Chromatography
In ion-exchange chromatography (IEC) the stationary phase is a cross-linked polymer resin, usually divinylbenzene cross-linked polystyrene, with covalently attached ionic functional groups. As shown here for a styrene–divinylbenzene co-polymer modified for use as an ion-exchange resin, the ion-exchange sites—indicated here by … Continue reading
HPLC Pumps
A typical HPLC includes between 1–4 reservoirs for mobile phase solvents. The mobile phase solvents are pulled from their reservoirs by the action of one or more pumps. Shown here is a close-up view of an instrument with two pumps, each … Continue reading
HPLC Column
The most common type of HPLC column is a stainless steel tube with an internal diameter between 2.1 mm and 4.6 mm and a length between 30 mm and 300 mm. The column is packed with 3–10 μm porous silica particles … Continue reading
HPLC Instrumentation
The photo below shows an example of a typical HPLC instrument with insets showing close-up views of the pumps that move the mobile phase through the system, and the plumbing used to inject the sample into the mobile phase. This particular instrument … Continue reading
GC Syringe
Shown here is an example of a syringe for injecting samples into a gas chromatograph. This syringe has a maximum capacity of 10 μL with graduations every 0.1 μL.
Gas Chromatography Columns
Shown here is an example of a packed column for gas chromatography. This column is made from stainless steel and is 2 m long with an internal diameter of 3.2 mm. The packing material in this column has a particle … Continue reading
Gas Chromatograph
Photograph showing an example of a typical gas chromatograph with insets showing the heated injection ports—note the symbol indicating that it is hot—and the oven containing the column. This particular instrument is equipped with an autosampler for injecting samples, a … Continue reading
Controlled-Potential Coulometry
Coulometry is based on an exhaustive electrolysis of the analyte. By exhaustive we mean that the analyte is completely oxidized or reduced at the working electrode or that it reacts completely with a reagent generated at the working electrode. During an … Continue reading