Phenols chromatographic systems

For a given chromatographic system and a series of different substituted phenols, the parameters a and b are constant, since 0 and for each of the substituted phenols (in a vertical configuration) is constant. Equation (1 l-2a) is tested in Fig. 11-4 against the data for one of the solvent systems studied by Bark and Graham. A resonable correlation of R versus (7 is observed. Although the data of Fig. 11-4 show more scatter than those of Fig. 1 l-3(a), in all but two cases the adsorption affinity of the substituted... 

To determine Irganox 1076, CAO-40, and Santonax R antioxidants in polyethylene the additives were extracted from the polymer by grinding them in a freezer mill then extracting with diethyl ether in a Soxhlet extractor for two days. The ether was then evaporated off and the residues dissolved in 25 cm of 1% by volume of isopropanol in hexane. Using the chromatographic system of a 1% isopropanol in hexane solvent and Corasil II adsorbent (surface area 14 2 mV ) and the conditions outlined below the amount of hindered phenolic antioxidant in the ether extract of the polymer was determined. Column 1000 inm x 2.1 mm, i.d. packing 37-50 u Corasil II (activated at 110°C) carrier 1% (v/v) iso-propanol in hexane flow rate - 0.95 ml/min. 

The surrogate compounds were mono-, tetra-, octa-, deca- C-PCBs, dg-naphthalene, C-PCP and C-phenol. The soil samples were dried with Na2S04 (60 g) and then Soxhlet extracted with hexane acetone (9 1) for 16 h. The extract was dried with sodium sulfate, concentrated, and split. While one portion was held for other analyses, the other portion was placed on a 3% deactivated silica gel column and eluted with increasing solvent polarity systems [hexane, followed by methylene chloride hexane (1 1), and then methylene chloride acetone (95 5)]. The extracts were combined and reduced to 1 mL, split and two internal standards added (tetrafluorobiphenyl and di2 Chrysene). The extracts were chromatographed on a 15-m DB-5 fused silica capillary column and detected with flame ionization (FID). Sludge samples were extracted according to the EPA sludge protocol (2) developed at Midwest Research Institute. 

III. HPLC SYSTEMS FOR PHENOLIC COMPOUNDS A. Chromatographic Conditions... 

For phenolics in fruit purees and jams (54), an HPLC condition similar to that used for apple juice, but with acidified water (5% formic acid) and methanol, was utilized as a solvent system. In most cases, detection was achieved with diode array detection, at UV 280 nm and 320 nm. The different phenolic compounds were identified by their UV spectra and by chromatographic comparisons with authentic standards. Several classes of phenolic compounds (cinnamic acids, catechins, dihydrochalcones, and flavonol glycosides) could be detected along with arbutin in... 

However, due to the artifacts resulting from oxidation, hydrolysis of esters or ethers, or isomerization of phenolics during pretreatment of wines, as well as due to the low recovery rates of some phenolics, analysis of wine phenolics via direct injection of the filtered wine into the chromatographic column is often selected (80,82-84). For the red wine and musts (80), which were injected directly into the HPLC without sample preparation, a ternary-gradient system was often employed for phenolic compounds. Twenty-two phenolic compounds, including 10 anthocyanins, were analyzed from red wine. The separation of cinnamic acid derivatives (313 nm),... 

Binary systems. A typical plot of the log of partition ratios (k ) vs. % modifier is presented in Figure 2. Like solvent strength, chromatographic retention is a nonlinear function of mobile phase composition. However, plots of log k vs solvent strength (i.e., Ej ) are linear, for at least some solutes, as shown for phenols... 

The HPLC chromatograph (Waters Associate Model A.I.C. 202) was used with solvent system of 60% hexane and k0% chloroform. A UV detector at 25 nm was used at an atenuation of x8 for camphor and x 6h for parachlorophenol and phenol. 

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