Gas and high-performance liquid chromatography of phenols

Tesařová, Eva; Pacáková, Věra

doi:10.1007/bf02263039

Cited by 65 publications

(12 citation statements)

References 216 publications

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“…Thus SCE-LC is a very powerful complement to conventional LC, and it is no surprise that SCE-LC has received considerable attention in the past (1)(2)(3)(4)(5)(6)(7)(8)(9).…”

mentioning

confidence: 99%

Optimization of secondary chemical equilibria in liquid chromatography: theory and verification

Foley¹,

May²

1987

Anal. Chem.

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A general theory for the optknlzatlon of secondary chemlcal equlllbrla In Hquld chromatography (SCE-LC) Is presented. Equations that predlct the opthnum moblle phase condltlons are derived expllcltly for the equillbrlum AX + A + X. The selectlvtty of SCE-LC has been substantially underestlmated because MMopthlun moMle phase condltkns were employed In previous selectlvlty estimates. An upper bound for the Selectivity Is given by cy I IOIb'I, where ApK Is the dHference In the equilibrium constants of the two solutes. The self-selectlvlty, or ratio of capaclty factors, klAX/klA, determines the moblle phase optlmum and the overall chromatographic selectlvlty whlch can be achleved. The maximum selectlvlty is predicted for several values of k',/k', and ApK. The opthnum concentratlon of equlllbrant, [ XI , , , can be predlcted from pX, = pK, , + (1/2) log (k'Ax/k'A), where pX, = -log [XI, and pKA,, Is the average effecthre equlllbrium constant of the two solutes. The theory Is experlmentally verlfled for acid-base equlllbrla.

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“…Thus SCE-LC is a very powerful complement to conventional LC, and it is no surprise that SCE-LC has received considerable attention in the past (1)(2)(3)(4)(5)(6)(7)(8)(9).…”

mentioning

confidence: 99%

Optimization of secondary chemical equilibria in liquid chromatography: theory and verification

Foley¹,

May²

1987

Anal. Chem.

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“…Gas chromatography (GC) has been used extensively to analyze phenolic resins for unreacted phenol monomer as well as certain two-and three-ring constituents in both novolak and resole resins (74). It is also used in monitoring the production processes of the monomers, eg, when phenol is alkylated with isobutylene to produce butylphenol.…”

Section: Chromatography Gel-permeation Chromatography (Gpc) Is Anmentioning

confidence: 99%

Phenolic Resins

Kopf¹

2003

Kirk-Othmer Encyclopedia of Chemical Technology

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Phenolic resins are a family of polymers and oligomers composed of a wide range of structures based on the various reaction products of phenols with formaldehyde. Applications vary from commodity construction materials to high technology applications in electronics and aerospace. Phenolic resins are prepared using acidic or basic catalysts. Weak Lewis acids, such as zinc acetate, are used for specialty resins. Phenolic novolaks are thermoplastic resins prepared from acid catalysts and a molar excess of phenol. They have a molecular weight of 500–5000 and a glass‐transition temperature T g of 45–70°C. Novolak resins are typically cured with 5–15% hexamethylenetetramine as the cross‐linking agent. Resole‐type phenolic resins are produced with a molar ratio of formaldehyde to phenol of 1.2:1 to 3.0:1 and alkaline catalysts such as NaOH, Ca(OH) 2 , and Ba(OH) 2 . A typical resin has an initial molecular weight of 150 to perhaps 1500. For systems of unsubstituted phenols, the final cross‐link density is 150–300 atomic mass units per cross‐link. In 2001, worldwide consumption of phenolic resins exceeded 4 × 10 6 t; slightly less than half of the total volume was produced in the United States, where the largest volume application is in plywood adhesives and accounts for ca 49% of U.S. consumption. As a mature industry, U.S. production of phenolic resins has paralleled the growth in the GNP. Applications for phenolic resins include coatings, adhesives, carbonless copy paper, molding compounds, bonded and coated abrasives, friction materials, foundry resins, laminates, air and oil filters, wood bonding, fiber bonding, composites, spherical fillers, and fibers. Factors contributing to the health and safety concerns of phenolic resins are related primarily to the presence of unreacted phenol and formaldehyde. Unreacted phenol in a resin can range from >10% for liquid resoles used in impregnation processes to <1% for novolaks intended for use as epoxy hardeners. Free formaldehyde can be 2–4% in liquid adhesives.

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“…Therefore, quantitative determination of nitrophenols, chlorophenols, and other organic acids in environmental samples is important. Most commonly, phenols have been determined by liquidliquid [10,11] or solid-phase extraction [12] followed by gas or liquid chromatography.…”

Section: Introductionmentioning

confidence: 99%