Quantitative analysis of total resin acids by high-performance liquid chromatography of their coumarin ester derivatives

Direct determination of resin and fatty acids in process waters of paper industries by liquid chromatography/mass spectrometry

Liquid chromatography/mass spectrometry (LC/MS)-based methods were developed for the analysis of 10 resin acids and five fatty acids in process waters of paper industries. No fragmentation of target compounds was observed using atmospheric pressure chemical ionization (APCI) with negative ionization. The [M - H](-) ion permitted the individual quantification of fatty and aromatic resin acids, whereas the non-aromatic resin acids presented a single and common ion at m/z 301. Separation with two columns of different polarity permitted peak confirmation. The method that used a C(8) column with 2-propanol in the mobile phase allowed a certain separation and identification of the non-aromatic resin acids, whereas the method using a C(18) column provided detection limits 10-fold lower for fatty acids. Limits of detection were 0.10 ng for all compounds. Direct sample introduction was compared with liquid-liquid extraction, with similar recoveries (70-101%). Whereas slightly lower detection limits were obtained with liquid-liquid extraction, better reproducibility was observed for direct sample introduction. Resin and fatty acids were determined in process waters of several paper industries. Palmitic, dehydroabietic and non-aromatic resin acids were encountered in most water samples, at levels between 22 and 403 micro g l(-1). LC/MS with direct sample introduction was found to be a good alternative to traditional liquid-liquid extraction and gas chromatography for the analysis of such compounds since no derivatization was required and sample manipulation was minimal.

Separation of resin acids using cyclodextrin-modified capillary electrophoresis

A cyclodextrin-modified capillary electrophoretic method has been developed for the analysis of eleven common resin acids using a pH 4.5, 20 mM sodium acetate buffer containing 10% acetonitrile, 20 mM methyl-beta-cyclodextrin (MECD) and 30 mM sulfobutylether-beta-cyclodextrin (SBCD) as buffer modifiers. At pH below their pKa (< 5.7-6.4) the resin acids were virtually unionized and insoluble; however, they formed water-soluble inclusion complexes with MECD (20 mM) or SBCD (30 mM) even at pH 4.5. The analytes were separated in 25 min and, with the exception of two pairs, 12- or 14-chlorodehydroabietic/12,14-dichlorodehydroabietic acid and dehydroabietic/palustric acid, the remaining resin acids were baseline-separated. Analysis time was significantly shortened (< 12 min) at pH 9.25 using 30 mM SBCD and 20 mM MECD in 20 mM sodium borate. Resin acids were baseline-separated with the exception of two pairs, pimaric/sandaracopimaric acid and 12- or 14-chlorodehydroabietic/abietic acid. The addition of 7.5% methanol to the running buffer resolved the abietic acid peak. Both HPLC and micellar capillary electrokinetic chromatography using 20 mM deoxycholic acid, 10% acetonitrile in 20 mM sodium borate, pH 9.25, failed to resolve the resin acids. The simple capillary electrophoretic method developed would be useful for the rapid separation and characterization of several important resin acids in pulp mill effluents and other contaminated samples.

Determination of resin acids in pulp mill EOP bleaching process effluent

Resin acids are tricyclic diterpenoids which are natural constituents of the wood from conifers. They are released from the wood during the manufacture of pulp and paper. These acids are very resistant to chemical degradation and survive the pulping and also the EOP bleaching process (EOP=alkaline extraction, oxygen and peroxide, the chemicals used in the bleaching process). Resin acids were extracted from alkaline medium using liquid-liquid extraction with t-butyl methyl ether and solid phase extraction with RP C18 adsorbent and a highly porous polystyrene-divinylbenzene polymer. After conversion of the acids to their pentafluorobenzyl esters, the extracts were analysed by GC/MS using a 25 m OV17 capillary column. Recovery values for single resin acids were determined by all three extraction methods. The solid phase extraction methods were applied to the analysis of the EOP effluent from a pulp mill bleaching process. 14 different resin acids and one resin acid methyl ester have been identified in the effluent. One of these was an oxo resin acid which might well be a product of the bleaching process.

Labeling of free carboxyl groups

The latest trends in the labeling of free carboxyl groups for high-performance liquid chromatography are reviewed. The labeling reagents for fluorescence detection are mainly discussed according to their reaction type (or functional group). Attention is also paid to the reagents used for ultraviolet detection and for enantiomeric separation. The reactivity and sensitivity of the reagents used for the labeling of carboxylic acids are described.

Quinoxalinone derivatization of biological carboxylic acids for detection by peroxyoxalate chemiluminescence with high-performance liquid chromatography

A quinoxalinone fluorescent tag is evaluated as a carboxylic acid derivatizing reagent for detection by peroxyoxalate chemiluminescence. The synthetic procedure for the quinoxalinone was modified to give a yield that is significantly increased over that reported previously. The new conditions use less hazardous reagents, and produce a final product greater than 97% pure, without the need for intermediate clean-up steps. The derivatization reaction is also modified to give increased yields of greater than 85% compared to 74% obtained previously. The post-column chemiluminescence reaction conditions are optimized to give detection limits of 500 attomole/injection-10 times lower than the fluorescence previously obtained. The reagent is used for the first time on a plasma sample extract. Typical method precision is 4%.