Glossary of terms used in separation science

Some of the following parameters must be considered to have a validated HPCE method for use with SOP, GMP, GLP and other pharmaceutical, environmental and forensic applications: Accuracy: How close the observed value is the to true value. This is analogous to an archer hitting the “intended” point each time he shoots his arrow. If the […]

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How do kinetics relate to the recovery in an SPE procedure?

With SPE, the analyte in the sample matrix is first loaded onto the SPE sorbent with one solvent and later eluted off of it with another. Because the SPE technique must be quantitative to be of use, these loading and elution steps must be complete. If not all of the adsorbed analyte is washed off of the sorbent, for example, then […]

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pK of Chemical Functional Groups

The dissociation constant (pK) is the pH at which 50% of a compound (functional group) is protonated. Following are some examples of Weak Acid and Weak Base Chemical Functional Groups and their approximate pK’s.   Acids pK  Sulfonic Acid <1  Phosphate Ester 2  Carboxylic Acid 2.5-5  Uracil 8  Sulfonamide 7-9  Guanine 2.2, 9.4  Phenol 8-10 […]

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Teflon© variations and uses in scientific labware

TEFLON© comes in many forms an varieties. Each form has different properties and costs. Below is a brief explanation of the different types of TEFLON© which is a registered trademark of E.I. DuPont. PFA PerFlourAlkoxy, has very low friction, excellent purity and excellent chemical resistance. Making it ideally suited for products serving the chromatography and other industries, it […]

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Terminology and Criteria for Chirality

Chiral compound pairs are two non-superimposable mirror images of each other (see Fig. 1). In their chemical structure, they must have one or more chiral centers (depicted by an up dash or down wedge). These chiral centers are usually but not always at a carbon. Compounds that have more than one chiral center cannot be chiral if they […]

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Types of isomers and suitable HPLC columns for separation

There are many types of chemical isomers, and each may require different approaches to obtain chromatographic separation. Some examples are as follows: Empirical Isomers: These compounds have the same empirical formula but the atoms could be arranged in any possible configuration. This is the most general type of isomer. Knowing all of the possible isomers […]

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What are the differences in the various autosampler vial tiers offered by MicroSolv?

MicroSolv has the world’s most comprehensive assortment of Vials, Caps & Inserts for every chromatography need. They are provided in 4 different “tiers” or levels to suit every lab’s analytical and budgetary requirements. Each tier/level is described below  including the value each type of vial, cap, limited volume insert or storage bottle provides. CLICK ON GRAPHICS TO […]

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What is a pyrogen?

The definition according to answers.com is “A pyrogen is defined as a fever-producing agent. Pyrogens are substances that cause febrile reactions when sufficient amounts enter the circulatory system. Bacterial endotoxin is the most significant pyrogen because of its potency and ubiquity.”

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What is an Octanol/Water Partition Coefficient? FAQ.

Basically, this is a measure of the hydrophobicity v. hydrophilicity of a compound. It is extremely useful when combined with the pI of your molecule to predict retention times. The Octanol-Water Partition Coefficient is a physical property used to describe a chemical’s lipophilic or hydrophobic properties. It is the ratio of the concentration of your […]

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What is Polyimide?

Polyimide is an aromatic, linear polymer. It is not a true thermoplastic because it thermally degrades before its glass transition temperature. It is not cross linked. It is used on CE capillaries because it is solvent resistant, possess barrier properties and performance at both high and low temperatures. Click here for Capillary Technical Properties.  MicroSolvCE Window Maker Information

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