Principles and Overview - Reference Methods - GC Methods - LC Methods - Other Methods - Pretreatment -
Ketoacids
(See also: DBP Methods and NOM Methods)
| Citation | Notes | Abstract |
|---|---|---|
| Citation | Notes | Abstract |
|---|---|---|
| Winslow, S.D., D.A. Cancilla, P. Snyder Fair, S.S. Que Hee, H. Yamada (2005). Method 6252: Disinfection Byproducts: Aldehydes (Proposed), In Standard Methods for the Examination of Water and Wastewater | Identical to EPA 556? | |
| Urbansky, E.T. (2000) Influences of metal cations on the determination of the alpha-oxocarboxylates as the methyl esters of the O-(2,3,4,5,6-pentafluorobenzyl)oximes by gas chromatography: the importance of accounting for matrix effects. Journal of Environmental Monitoring 2(4), 334-338. | Problems with metals | The alpha-oxocarboxylates (alpha-ketocarboxylates) and the corresponding alpha-oxoacids (alpha-ketoacids) have been reported as disinfection byproducts of ozonation of potable water supplies. In this analytical method, the oxo moiety is derivatized with O-(2,3,4,5,6-pentafluorobenzyl)oxylamine (PFBOA) to form an oxime which is then extracted into tert-butyl methyl ether. The carboxylic acid moiety is esterified (methylated) with diazomethane. In this study, five analytes were investigated: oxoethanoate (glyoxylate), 2-oxopropanoate (pyruvate), 2-oxobutanoate (2-ketobutyrate), 2-oxopentanoate (2-ketovalerate), and oxopropanedioate (ketomalonate, mesoxalate). The influence of Lewis acid metal cations in the water matrix was evaluated for the gas chromatographic method commonly used for the quantitation of these analytes at concentrations less than or equal to 150 ng mL(-1). Tested metals included Ca(II), Mg(II), Fe(III), Cu(II) and Zn(II). At typical concentrations, calcium, in particular, can have profound impact, especially on oxoethanoate quantitation. Oxopropanoate experiences an increase in recovery in the presence of metal cations. 2-Oxobutanoate and 2-oxopentanoate are the most resistant to these effects, but 2-oxopentanoate shows increased recoveries at higher concentrations when assayed in the presence of calcium ion. Oxopropanedioate generally shows poorer precision and recovery when determined in solutions containing metal ions. This investigation demonstrates the significance of metal effects in the quantitative determination of these analytes and further emphasizes the importance of thorough matrix characterization and careful recovery studies with fortified (spiked) samples and blanks. |
Munch, J.W., D.J. Munch, S.D. Winslow, S.C. Wendelken, and B.V. Pepich. 1998. Method 556: Determination of Carbonyl Compounds in Drinking Water by Pentafluorobenzylhydroxylamine Derivatiation and Capillary Gas Chromatography with Electron Capture Detection, EPA, Cincinnati, OH. |
generally accepted method | This is a gas chromatographic method optimized for the determination of selected carbonyl compounds in finished drinking water and raw source water. The analytes applicable to this method are derivatized to their corresponding pentafluorobenzyl oximes. The oxime derivatives are then extracted from the water with hexane. The hexane extracts are analyzed by capillary gas chromatography with electron capture detection (GC-ECD) and quantitated using procedural standard calibration. |
| Citation | Notes | Abstract |
|---|---|---|
| Ye, Q., Zheng, D.G., Liu, L.H. and Hong, L.M. (2011) Rapid analysis of aldehydes by simultaneous microextraction and derivatization followed by GC-MS. Journal of Separation Science 34(13), 1607-1612. |
simultaneous LLE & PFBHA | Ultrasound-assisted dispersive liquid-liquid microextraction (UDLLME) and simultaneous derivatization followed by GC-MS was developed for the analysis of four aldehydes including acetaldehyde (ACE), propionaldehyde (PRO), butyraldehyde (BUT) and valeraldehyde (VAL) in water samples. In the proposed method, the aldehydes were derivatized with O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine (PFBHA) and extracted by UDLLME in aqueous solution simultaneously; finally, the derivatives were analyzed by GC-MS. The experimental parameters were investigated and the method validations were studied. The optimal conditions were: aqueous sample of 5 mL, PFBHA of 50 mu L, 1.0 mL ethanol (disperser solvent) containing 20 mL chlorobenzene (extraction solvent), ultrasound time of 2 min and centrifuging time of 3 min at 6000 rpm. The proposed method provided satisfactory precision (RSD 1.8-10.2%), wide linear range (0.8-160 mu g/L), good linearity (R(2) 0.9983-0.9993), good relative recovery (85-105%) and low limit of detection (0.16-0.23 mu g/L). The proposed method was successfully applied for the analysis of aldehydes in water samples. The experimental results showed that the proposed method was a very simple, rapid, low-cost, sensitive and efficient analytical method for the determination of trace amount of aldehydes in water samples. |
| Hudson, E.D., Ariya, P.A. and Gelinas, Y. (2011) A method for the simultaneous quantification of 23 C-1-C-9 trace aldehydes and ketones in seawater. Environmental Chemistry 8(4), 441-449. |
Low molecular weight aldehydes and ketones in the surface oceans are produced by dissolved organic matter photochemistry or by biology, and can be transferred to the atmosphere, affecting its oxidative capacity. They therefore link the organic carbon biogeochemistry of the atmosphere and the oceans. We have developed and optimised a mobile, economical and facile method which allows for the simultaneous quantification of 23 C-1-C-9 low molecular weight aldehydes and ketones in seawater. The compounds are derivatised using O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA), pre-concentrated by solid-phase microextraction and analysed by gas chromatography with mass spectrometric or flame ionisation detection. Detection limits range from 0.01 to 23.5 nM, depending on the compound, with subnanomolar detection limits achieved for most compounds. High process blanks were observed for C-1-C-3 carbonyl compounds; sparging with ultrahigh purity argon, and solid phase extraction of the dissolved PFBHA to remove preexisting carbonyl oximes, were the most effective blank reduction methods. The method was applied to surface waters from the lower St Lawrence Estuary (Quebec, Canada), revealing C-2-C-6 carbonyl compounds at concentrations of up to 7.5 nM. | |
| Schmarr, H.G., Sang, W., Ganss, S., Fischer, U., Kopp, B., Schulz, C. and Potouridis, T. (2008) Analysis of aldehydes via headspace SPME with on-fiber derivatization to their O-(2,3,4,5,6-pentafluorobenzyl)oxime derivatives and comprehensive 2D-GC-MS. Journal of Separation Science 31(19), 3458-3465. |
A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC x GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC x GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d(16)-al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC x GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis. | |
| Gabrio, T. and Bertsch, A. (2004) Determination of carbonyl compounds in pool water with O-(2,3,4,5,6-pentafluorobenzyl)hydroxyamine hydrochloride and gas chromatographic-tandem mass spectrometric analysis. Journal of Chromatography A 1046(1-2), 293-296. |
To avoid microbiological decay pool water is disinfected, a procedure which results into a lot of disinfection by-products, like carbonyl compounds, as well as a large number of others. The carbonyl compounds dissolved in pool water were derivatisized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxyamine hydrochloride (PFBHA) and extracted using n-hexane. Measuring with the help of GC-electron-capture detection is hardly possible because of interferents like halogenated organics. Another method to detect the PFBHA derivates is the use of tandem mass spectrometry. Calibration ranges and precision are applicable and sufficient to determine carbonyl compounds in pool water. | |
| Tsai, S.W. and Chang, C.M. (2003) Analysis of aldehydes in water by solid-phase microextraction with on-fiber derivatization. Journal of Chromatography A 1015(1-2), 143-150. |
SPME | The solid-phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of aldehydes in water.The poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber was used and O-2,3,4,5,6-(pentafluorobenzyl)hydroxyl-amine hydrochloride (PFBHA) were first loaded onto the fiber. The aldehydes in water sample were agitated into headspace and extracted by SPME with on-fiber derivatization. Gas chromatography/mass spectrometry (GC/MS) was used for the analysis of oximes formed and the adsorption-time profiles were examined. The precision, recovery and method detection limits (MDLs) were evaluated with spiked bidistilled water, chlorinated tap water as well as well water. The relative standard deviations from different spiked water sample were all less than 10% and the recoveries were 100 +/- 15%. With 2 ml of water sample, MDLs were in the range of 0.12-0.34 mug/l. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of aldehydes in water. |
Nawrocki, J., I. Kalkowska, and A. Dabrowska. 1996. Optimization of solid-phase extraction method for analysis of low-ppb amounts of aldehydes-ozonation by-products. Journal of Chromatography A 749:157-163. |
Ozonation is commonly used in drinking water treatment technology. Ozone reacts with natural organic substances present in water to produce a number of by-products. Aldehydes are the important class of ozonation byproducts due to their health effects. The determination of aldehydes in water by conventional analytical techniques is difficult because they are polar, unstable and exist at low concentration. A modern method for the determination of aldehydes in drinking water applies derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA) and liquid-liquid extraction (LLE). The objective of this study was to improve the method by application of solid-phase derivatization and extraction. C-18, C(18)polar plus and Phenyl Baker SPE sorbents were used for simultaneous derivatization and enrichment of aldehydes. Detection limits with GC-electron-capture detection technique were in the low ppt range. | |
| Cancho, B., F. Ventura, and M.T. Galceran. 2002. Determination of Aldehydes in Drinking Water Using Pentafluorobenzylhydroxylamine Derivatization and Solid-Phase Microextraction. Journal of Chromatography a 943:1-13. | SMPE method | A headspace solid-phase microextraction (HS-SPME) procedure followed by gas chromatography and electron capture detection (GC-ECD) has been developed for the determination of aldehydes in drinking water samples at mug/l concentrations. A previous derivatization with o-(2,3,4,5,6- pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was performed due to the high polarity and instability of these ozonation by-products. Several SPME coatings were tested and the divinylbenzene-polydimethylsiloxane (DVB-PDMS) coating in being the most suitable for the determination of these analytes. Experimental SPME parameters such as selection of coating, sample volume, addition of salt, extraction time and temperature of desorption were studied. Analytical parameters such as precision, linearity and detection limits were also determined. HS-SPME was compared to liquid-liquid microextraction (proposed in US Environmental Protection Agency Method 556) by analyzing spiked water samples; a good agreement between results obtained with both techniques was observed. Finally, aldehydes formed at the Barcelona water treatment plant (N.E. Spain) were determined at levels of 0.1-0.5 mug/l. As a conclusion, HS-SPME is a powerful tool for determining ozonation by-products in treated water. |
| Citation | Notes | Abstract |
|---|---|---|
|
||
| Fernandez-Molina, J.M. and Silva, M. (2011) Simple and sensitive determination of low-molecular-mass aromatic aldehydes in swimming pool water by LC-diode array detector. Journal of Separation Science 34(19), 2732-2738. |
PDA | This work reports the development of a simple method for the quantitative determination of aromatic and aliphatic low-molecular-mass aldehydes (LMMAs) as disinfection by-products (DBPs) in indoor swimming pool waters after chlorination with a simplified SPE sample treatment. The method is based on the continuous in situ derivatization/preconcentration of the aldehydes with 2,4-dinitrophenylhydrazine (DNPH) on a Lichrolut EN column in the presence of beta-CD. After elution, the 2,4-dinitrophenylhydrazine derivatives were separated on an RP-C(18) analytical column using gradient of ACN-water at 60-80%. The optimized sample treatment described here allowed the direct analysis of large volumes of water in order to improve the sensitivity of the method; LODs in the 60-120 ng/L range were achieved for aromatic LMMAs by using a volume of 50 mL of water, precision being 7.5% or better at a concentration level of 5 mu g/L. These results indicate that the ensuing method is a useful choice for the determination of LMMAs in water samples that provides better results than reported LC alternatives in terms of the LOD (except for MS/MS detection), sample requirements for analysis and cost. |
| Houdier, S., Barret, M., Domine, F., Charbouillot, T., Deguillaume, L. and Voisin, D. (2011) Sensitive determination of glyoxal, methylglyoxal and hydroxyacetaldehyde in environmental water samples by using dansylacetamidooxyamine derivatization and liquid chromatography/fluorescence. Analytica Chimica Acta 704(1-2), 162-173. |
fluorescence | In this study we improved the dansylacetamidooxyamine (DNSAOA)-LC-fluorescence method for the determination of aqueous-phase glyoxal (GL), methylglyoxal (MG) and hydroxyacetaldehyde (HA). As derivatization of dicarbonyls can potentially lead to complex mixtures, a thorough study of the reaction patterns of GL and MG with DNSAOA was carried out. Derivatization of GL and MG was shown to follow the kinetics of successive reactions, yielding predominantly doubly derivatized compounds. We verified that the bis-DNSAOA structure of these adducts exerted only minor influence on their fluorescence properties. Contrary to observations made with formaldehyde, derivatization of GL, MG and, to a lesser extent of HA, was shown to be faster in acidic (H(2)SO(4)) medium with a maximum of efficiency for acid concentrations of ca. 2.5 mM. Concomitant separation of GL, MG, HA and of single carbonyls was achieved within 20 min by using C(18) chromatography and a gradient of CH(3)CN in water. Detection limits of 0.27, 0.17 and 0.12 nM were determined for GL, MG and HA, respectively. Consequently, low sample volumes are sufficient and, unlike numerous published methods, neither preconcentration nor large injection volumes are necessary to monitor trace-level samples. The method shows relative measurement uncertainties better than +/- 15% at the 95% level of confidence and good dynamic ranges (R(2) > 0.99) from 0.01 to 1.5 mu M for all carbonyls. GL, MG and HA were identified for the first time in polar snow samples, but also in saline frost flowers for which unexpected levels of 0.1-0.6 mu M were measured. Concentrations in the 0.02-2.3 mu M range were also measured in cloud water. In most samples, a predominance of HA over GL and MG was observed. |
| Ochs, S.D., Fasciotti, M., Barreto, R.P., de Figueiredo, N.G., Albuquerque, F.C., Massa, M., Gabardo, I. and Netto, A.D.P. (2010) Optimization and comparison of HPLC and RRLC conditions for the analysis of carbonyl-DNPH derivatives. Talanta 81(1-2), 521-529. |
PDA | Analytical conditions for the analysis of 15 carbonyl-DNPH derivatives were optimized and compared by high performance liquid chromatography (HPLC) and rapid resolution liquid chromatography (RRLC). Binary, ternary and quaternary mixtures of acetonitrile, isopropanol, methanol, tetrahydrofuran and water were evaluated under RRLC conditions employing a Zorbax Eclipse Plus C18 (50 mm x 4.6 mm x 1.8 mu m) column and a Zorbax Eclipse Plus C18 (50 mm x 2.1 mm x 1.8 mu m) column. The optimized conditions obtained employing the two RRLC columns were compared with those obtained using a Supelcosil C18 (250 mm x 4.6 mm x 5 mu m: Supelco) that is designed for HPLC separation of DNPH derivatives. Chromatograms run with a Zorbax Eclipse Plus C18 (50 mm x 2.1 mm x 1.8 mu m) column and a mobile phase composed of isopropanol, methanol, tetrahydrofuran and water led to the best separation conditions considering reduced analysis time (similar to 6 min per run), solvent consumption rate (similar to 2 mL per run) and resolution of propanone, acrolein and propionaldehyde hydrazones. Quantification limits and linear ranges were adequate for direct application of EPA TO-11 conditions in all sets of RRLC and HPLC conditions. The analytical method was applied in the determination of carbonyl compounds (CCs) in Niteroi City, RJ, Brazil in samples that were collected during periods of 2 h. Formaldehyde (8.22-9.78 ppbv) predominated in all periods followed by acetaldehyde (1.77-3.99 ppbv) and propanone (1.89-3.26 ppbv). Heavy CCs such as butyraldehyde and benzaldehyde were also detected in most samples. Total CCs varied along the studied day. The obtained results showed that RRLC can be applied to CCs determination without any change in the conditions of sample preparation of the Method EPA TO-11. |
| Takeda, K., Katoh, S., Nakatani, N. and Sakugawa, H. (2006) Rapid and Highly Sensitive Determination of Low-molecular-weight Carbonyl Compounds in Drinking Water and Natural Water by Preconcentration HPLC with 2,4-dinitrophenylhydrazine. Analytical Sciences 22(12), 1509-1514. |
UV/Vis | The aim of this research was to develop a simple procedure for a highly sensitive determination of low-molecular-weight (LMW) carbonyl compounds in drinking water and natural water. We employed a preconcentration HPLC system with 2,4-dinitrophenylhydrazine (DNPH) for the determination of LMW carbonyl compounds. A C-18 reverse-phase preconcentration column was used instead of a sample loop at the sample injection valve. A 0.1 - 5.0 mL portion of the derivatized sample solution was injected with a gas-tight syringe, and a 15% acetonitrile aqueous solution was pushed through the preconcentration column to remove the unreacted excess DNPH, which caused serious interference in the determination of formaldehyde. The detection limits were 1 - 3 nM with a relative standard deviation of 2 - 5% for 20 nM standard solutions (n = 5). The calibration curves were essentially unaffected by coexisting sea salts. Applications to commercial mineral water, tap water, river water, pond water and seawater are presented. |
| Citation | Notes | Abstract |
|---|---|---|
Banos, C.E. and Silva, M. (2010) Analysis of low-molecular mass aldehydes in drinking waters through capillary electrophoresis with laser-induced fluorescence detection. Electrophoresis 31(12), 2028-2036. |
CZE | The potential of CZE with LIF detection in the separation and determination of low-molecular mass aldehydes involving precolumn derivatization with fluorescein 5-thiosemicarbazide was investigated. Different variables that affect derivatization (pH, fluorescein 5-thiosemicarbazide concentration, time and temperature) and separation (pH and concentration of the BGE, kind and concentration of surfactants at levels higher and lower than CMC, and applied voltage) were studied. The separation was conducted within 16 min by using borate buffer (60 mM; pH 10) with 10) mu M polyethylene glycol tert-octylphenyl ether as modifier. Good linearity relationships (correlation coefficients ranged from 0.9978 to 0.9994 for aldehydes) were obtained between the peak areas and concentration of the analytes (0.5-100 mu g/L). The LODs for aldehydes were achieved at submicrogram-per-liter level (0.15-0.35 mu g/L), which indicated that the proposed method surpassed other electrophoretric alternatives in terms of LOD, in many cases even at ca. 1000-fold. The inter-day precision (RSD, %) of the aldehydes ranged from 5.2 to 8.3%. Finally, the method was successfully applied to bottled drinking-water samples, and the aldehydes were readily detected at 0.6-4.4 mu g/L levels with average recoveries ranging from 99.1 to 103.5% |
| Citation | Notes | Abstract |
|---|---|---|
| Banos, C.E. and Silva, M. (2009) In situ continuous derivatization/pre-concentration of carbonyl compounds with 2,4-dinitrophenylhydrazine in aqueous samples by solid-phase extraction Application to liquid chromatography determination of aldehydes. Talanta 77(5), 1597-1602. | A rapid and straightforward continuous solid-phase extraction system has been developed for in situ derivatization and pre-concentration of carbonyl compounds in aqueous samples Initially 2,4-dinitrophenylhydrazine, the derivatizing agent, was adsorbed on a C-18 mini-column and then 15-ml of sample were continuously aspirated into the flow system, where the derivatization and pre-concentration of the analytes (low-molecular mass aldehydes) were performed simultaneously. Following elution, 20 mu l of the extract were injected into a LC-DAD system. in which hydrazones were successfully separated in 12 min on a RP-C-18 column using a linear gradient mobile phase of acetonitrile-water of 60-100% acetonitrile for 8 min. flowing at 0.5 ml/min. The whole analytical process can be accomplished within ca. 35 min. Under optimum conditions, limits of detection were obtained between 0.3 and 1.0 mu g/l and RSDs (inter-clay precision) from 1.2 to 4.6%. Finally, some applications on water samples are presented with recoveries ranged from 95.8 to 99.4% | |
| Gupta, M., Jain, A. and Verma, K.K. (2009) Salt-assisted liquid-liquid microextraction with water-miscible organic solvents for the determination of carbonyl compounds by high-performance liquid chromatography. Talanta 80(2), 526-531. |
A simple and rapid method has been reported for the determination of carbonyl compounds involving reaction with 2,4-dinitrophenylhydrazine and extraction of hydrazones with water-miscible organic solvent acetonitrile when the phase separation occurs by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 360 nm. The procedure has been optimized with respect to solvent suitable for extraction, salt for phase separation between water and organic solvent, reaction temperature and reaction time. The method has been validated when a linear dynamic range was obtained between the amount of analyte and peak area of hydrazones in the range 7 mu g-15 mg L(-1), the correlation coefficient over 0.9964-0.9991. and the limit of detection in the range 0.58-3.2 mu g L(-1). Spiked water samples have been analyzed with adequate accuracy, and application of the method has been demonstrated in the analysis of benzalclehyde formed as oxidation product in pharmaceutical preparation where benzyl alcohol is used as preservative, and for a keto drug dexketoprofen. | |
Beranek, J. and Kubatova, A. (2008) Evaluation of solid-phase microextraction methods for determination of trace concentration aldehydes in aqueous solution. Journal of Chromatography A 1209(1-2), 44-54. |
A method for trace analysis of a wide range of aldehydes (saturated/unsaturated aliphatic, aromatic aldehydes, including hydroxylated species, and dialdehydes) in an aqueous solution was optimized. An evaluation of three solid-phase microextraction (SPME) techniques (headspace, liquid-phase, and on-fiber derivatization) with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) aldehyde derivatization was performed focusing on the optimization of the main extraction parameters (temperature and time). The optimized method employed the liquid-phase SPME (D-L-SPME) of derivatized aldehydes at 80 degrees C for 30min. Limits of detection (LODs) using this optimal method were in the range of 0.1-4.4 mu g/L for the majority of aliphatic (saturated, unsaturated), aromatic aldehydes and dialdehydes. Formaldehyde LODs and those of some hydroxylated aromatic aldehydes were between 32 and 55 mu g/L. Headspace SPME using an on-fiber derivatization generally showed a lower sensitivity and several compounds were not detected. Another technique, the optimized headspace SPME of aldehydes derivatized in aqueous solution, was not as sensitive as D-L-SPME for hydroxylated aromatic aldehydes. The developed method was used to analyze aqueous particulate matter extracts; this method achieved higher sensitivities than those obtained with US Environmental Protection Agency (EPA) Method 556 | |
| Spaulding, R.S. and Charles, M.J. (2002) Comparison of methods for extraction, storage, and silylation of pentafluorobenzyl derivatives of carbonyl compounds and multi-functional carbonyl compounds. Analytical and Bioanalytical Chemistry 372(7-8), 808-816. |
The employment of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatization along with bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N,N-(tertbutyldimethylsilyl)trifluoroacetamide (MTBSTFA) derivatization is a popular method for measurement of oxygenated organics in environmental and biological samples. Most notably, the derivatization method enables the measurement of atmospheric photooxidation products not detected by using other methods. PFBHA derivatization is often conducted in an aqueous solution. Accordingly, experiments were performed to compare the efficiency of hexane, methyl-tert-butyl ether (MTBE), and dichloromethane (CH2Cl2) for extraction of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatives of carbonyl compounds from water. Further, the stability of these compounds when stored at 4degreesC in CH2Cl2 was determined, and commonly used methods for silylation of -OH and -COOH groups on the PFBHA derivatives were compared. Overall, CH2Cl2 was the most efficient solvent for extraction of PFBHA derivatives of hydroxycarbonyl compounds, dicarbonyl compounds, and keto-acids from water. Derivatives of carbonyl compounds that do not have secondary functional groups were extracted with approximately equal efficiency by each of the three solvents examined. The PFBHA derivatives of aromatic and saturated aliphatic carbonyl compounds and hydroxycarbonyl compounds were stable in CH2Cl2 at 4degreesC for greater than or equal to66 days whereas the derivatives of keto-acids and unsaturated aliphatic aldehydes begin to degrade after approximately 38 days. Comparison of four procedures for bis-(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization. of -OH and -COOH groups on PFBHA derivatives revealed that primary -OH groups react efficiently in 20-100% BSTFA in CH2Cl2, and do not require a catalyst. Secondary -OH groups also react efficiently in 20-100% BSTFA, but the reaction yield improves slightly when trimethylchlorosilane (TMCS) is added as a catalyst. Reaction of tertiary -OH groups with BSTFA was very inefficient, but improved with addition of 10% TMCS to the BSTFA solution. Finally, -COOH groups seemed to react most efficiently and consistently in 100% BSTFA, without catalyst. | |
| Nawrocki, J., Kalkowska, I. and Dabrowska, A. (1996) Optimization of solid-phase extraction method for analysis of low-ppb amounts of aldehydes-ozonation by-products. Journal of Chromatography A 749(1-2), 157-163. |
Ozonation is commonly used in drinking water treatment technology. Ozone reacts with natural organic substances present in water to produce a number of by-products. Aldehydes are the important class of ozonation byproducts due to their health effects. The determination of aldehydes in water by conventional analytical techniques is difficult because they are polar, unstable and exist at low concentration. A modern method for the determination of aldehydes in drinking water applies derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA) and liquid-liquid extraction (LLE). The objective of this study was to improve the method by application of solid-phase derivatization and extraction. C-18, C(18)polar plus and Phenyl Baker SPE sorbents were used for simultaneous derivatization and enrichment of aldehydes. Detection limits with GC-electron-capture detection technique were in the low ppt range. |
| Citation | Notes | Abstract |
|---|---|---|
Xie, Y.F., Reckhow, D.A. and Springborg, D.C. (1998) Analyzing Haas and Ketoacids Without Diazomethane. Journal American Water Works Association 90(4), 131-138. |
Currently available methods for analyzing haloacetic acids (HAAs) and ketoacids in water generally require the use of diazomethane for sample derivatization. This article proposes methods based on a less toxic, alternative methylating agent. The reagent in both cases is acidic methanol. Side-by-side comparison of the proposed method for HAA analysis and method 6251B showed no significant difference. These two methods were also found to give similar method detection limits and spike recoveries. The new O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBHA)-acidic methanol derivatization analytical method for two ketoacids-glyoxylic acid and pyruvic acid-was found to be comparable to the method using PFBHA-diazomethane. Additional study is needed to improve methylation efficiency for ketomalonic acid. Work is also needed to further test the proposed HAA method with monochloroacetic acid and brominated haloacetic acids. |
Related Information: UMass LC/MS Instrument pages: Quattro Micro; Quattro Premier