Separation of C1-C5 aliphatic carboxylic acids on a highly sulfonated styrene-divinylbenzene copolymer resin column with a C6 aliphatic carboxylic acid solution as the mobile phase

Simultaneous separation of C₁-C₅ aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, butyric, iso-valeric and valeric acids) on a highly sulfonated styrene-divinylbenzene copolymer resin column (TSKgel SCX,  mm i.d.) was performed with C₆ aliphatic carboxylic acids (3-methyl-n-valeric, iso-caproic and caproic acids) solutions as the mobile phases. Using 0.05 mM sulfuric acid at pH 4.0 as the mobile phase, although good separation of these C₁-C₅ acids was achieved, peaks of the C₅ acids (iso-valeric and valeric acids) with large hydrophobicity tailed strongly. In contrast, using 1 mM C₆ acids at pH ca. 4.0 as the mobile phases, although vacant peaks corresponding to the C₆ acids in the mobile phase appeared, the peak shapes of the C₅ acids were improved greatly. Excellent simultaneous separation, symmetrical peaks and relatively high-sensitivity conductimetric detection for these C₁-C₅ acids were achieved on the TSKgel SCX column in 15 min with 1 mM iso-caproic acid at pH 4.0 as the mobile phase.     

Determination of the carboxylic acids in acidic and basic process samples by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) with indirect UV detection was used in developing a method for the simultaneous determination of inorganic anions, aliphatic and heterocyclic organic acids in various processed samples. The analytes were determined simultaneously in 10 min using an electrolyte containing 20 mM 2,3-pyrazine dicarboxylic acid, 65 mM tricine, 2 mM BaCl₂, 0.5 mM cetyltrimethylammonium bromide, and 2 M urea at pH 8.06. Linear plots for the analytes were obtained in the concentration range of 2–150 mg L⁻¹. Relative standard deviations (RSDs) of peak areas during a 3-day analysis period varied from 5.5% for glycolate to 9.5% for oxalate. RSDs of migration times varied between 0.4% and 1.1%. The detection limit (at S/N 3) was 1 mg L⁻¹ for all the analytes studied. The proposed method was successfully demonstrated for the determination of carboxylic acids in eight oxygen treated samples of commercial softwood and hardwood kraft lignin and two red wine samples of Pinot Noir grapes. In the kraft lignin samples the concentrations of carboxylic acids correspond to the oxidation time. The acid concentrations of wine varied considerable.     

Application of flow-injection potentiometric system for determination of total concentration of aliphatic carboxylic acids

In this work, flow-injection system with potentiometric detection was tested for determination of total carboxylic acid concentration. Detection part of the examined system consists of ion-selective electrodes (ISEs) with polymer membranes of different compositions. First electrode is based on Zr(IV)-tetraphenylporphyrin as ionophore selective towards carboxylic acid anions, the membrane of second one contains only liphophilic anion exchanger - tridodecylmethylammonium chloride. Final response of the system is a result of combination of EMF signals from both electrodes. Combination of two detectors enables significant decrease of differences between potentiometric signals induced by mixtures of studied anions of various concentrations as compared to results obtained only with metalloporphyrin-based ISE. The use of anion-exchanger based detector allows for elimination of the influence of aliphatic carboxylic acids lipophilicity.Proposed potentiometric flow-injection system was employed for determination of short-chain aliphatic carboxylic acids (so-called VFA - volatile fatty acids) in samples originating from an anaerobic digester. Results obtained for these relatively complicated samples are in good agreement with results obtained with the use of reference colorimetric method.Linear response towards carboxylic acids was observed in the concentration range of 10⁻⁴ to 10⁻² mol dm⁻³, with the slopes in the range of −110 to −150 mV dec⁻¹ (for acetate⁻ and butyrate⁻, respectively). System enables for determination of about 6 samples per hour. Life time of ISEs average about 2 months.     

Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column

The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences.     

Copper-catalyzed decarboxylative coupling reactions for the synthesis of propargyl amines

When aryl alkynyl carboxylic acids were allowed to react with amines and aldehydes in CH₃CN at 80 °C in the presence of 10 mol % CuI, the desired propargyl amines were formed in good yields. This coupling reaction demonstrated to work across a broad range of reagents including functionalized aryl alkynyl carboxylic acids, aliphatic and aromatic aldehydes, and cyclic and acyclic amines.     

Capillary electrophoresis for the monitoring of carboxylic acid production by Gluconobacter oxydans

Determination of carboxylic acids in Gluconobacter oxydans fermentations of wheat straw hydrolyzate was carried out. This matrix is of complex composition containing carbohydrates, organic compounds (e.g., amino acids, toxins), and inorganic salts making the analysis challenging even with separation techniques. A method based on capillary electrophoresis with indirect UV detection was developed for the simultaneous quantification of 18 carboxylic acids. The background electrolyte solution of ammonia, 2,3-pyridinedicarboxylic acid, and Ca²⁺ and Mg²⁺ salts, containing myristyltrimethylammonium hydroxide as a dynamic capillary coating reagent, was validated for the robust and repeatable separation of the carboxylic acids. Intraday relative standard deviations in the optimized method were less than 1.6% for migration times and between 1.0% and 5.9% for peak area. Interday relative standard deviations were less than 5.0% for migration times and between 5.7% and 9.3% for peak area. With 11 nl injected, detection limits for the analytes were between 10 and 43 μmol/l. Detection limits ranged from 0.1 to 0.5 pmol at signal-to-noise ratio of 3. The results demonstrated that wheat straw hydrolyzate was a suitable substrate for G. oxydans with a product yield of 45% for the formation of xylonic acid from xylose and 96% for the formation of gluconic acid from glucose.     

A naphthyridine-based receptor for sensing citric acid

A naphthyridine-based charge neutral receptor has been designed and synthesized. Its complexation with a series of carboxylic acids involved in the Krebs cycle has been studied by ¹H NMR, UV-vis and fluorescence methods. The receptor shows strong binding to citric acid (K_a = 1.60 × 10⁵ M⁻¹) and is also able to distinguish diastereomeric maleic acid from fumaric acid by fluorescence.     

Identification and determination of carboxylic acids in food samples using 2-(2-(anthracen-10-yl)-1H-phenanthro[9,10-d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) as labeling reagent by HPLC with FLD and APCI/MS

A new labeling reagent for carboxylic acids, 2-(2-(anthracen-10-yl)-1H-phenanthro[9,10-d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) has been designed and synthesized. It was used to label eight fatty acids (lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, linoleic acid and linolenic acid) and four hydroxy pentacyclic triterpene acids (oleanolic acid, ursolic acid, betulinic acid and maslinic acid), successfully. APIETS could easily and quickly label carboxylic acids in the presence of K₂CO₃ catalyst at 85 °C for 35 min in N,N-dimethylformamide solvent. The carboxylic acids derivatives were separated on a C₈ reversed-phase column with gradient elution and fluorescence detection at λ_ex/λ_em = 315/435 nm. Identification of these derivatives was carried out by online mass spectrometry with atmospheric pressure chemical ionization in positive ion mode. The detection limits obtained were 13.37-30.26 fmol (signal-to-noise ratio of 3). The proposed method has been applied to the quantification of carboxylic acids in sultana raisin (Thompson seedless), hawthorn flake (Crataegus pinnatifida Bge.), Lycium barbarum seed oil and Microula sikkimensis seed oil with recoveries over 95.3%. It has been demonstrated that APIETS is a prominent labeling reagent for determining carboxylic acids with high performance liquid chromatography.     

Ion-exclusion chromatography with the direct UV detection of non-absorbing inorganic cations using an anion-exchange conversion column in the iodide-form

An ion-exclusion chromatographic method for the direct UV detection of non-absorbing inorganic cations such as sodium (Na⁺), ammonium (NH₄⁺) and hydrazine (N₂H₅⁺) ions was developed by connecting an anion-exchange column in the I⁻-form after the separation column. For example, NH₄⁺ is converted to a UV-absorbing molecule, NH₄I, by the anion-exchange column in the I⁻-form after the ion-exclusion separation on anion-exchange column in the OH⁻-form with water eluent. As a result, the direct UV detection of Na⁺, NH₄⁺ and N₂H₅⁺ could be successfully obtained as well as the well-resolved separation. The calibration graphs of the analyte cations detected with UV at 230 nm were linear in the range of 0.001-5.0 mM. The detection limits at S/N = 3 of the cations were below 0.1 μM. This method was applied to real water analysis, the determination of NH₄⁺ in river and rain waters, or that of N₂H₅⁺ in boiler water, with the satisfactory results. This could be applied also to low- or non-absorbing anions such as fluoride or hydrogencarbonate ions by the combination of a weakly acidic cation-exchange resin in the H⁺-form as the separation column and the anion-exchange conversion column.     

Hydrogels based on carboxymethyl cassava starch cross-linked with di- or polyfunctional carboxylic acids: Synthesis, water absorbent behavior and rheological characterizations

Carboxymethyl cassava starch (CMS) was synthesized and its hydrogels were prepared by cross-linking it with di- or polyfunctional carboxylic acids using glutaric (CASXGLU), suberic (CASXSUB), pimelic (CASXPIM) and butanetetracarboxylic acids (CASBTC) as the cross-linkers. The characterization of the CMS showed that its degree of substitution was 0.86, average molar mass (M_w) was 5.6 × 10⁶ g mol⁻¹ and the ¹³C NMR showed strong peak at δ = 180.42 ppm which was assigned to the CO carbon in the carboxymethyl group. The absorption under load (AUL) and free swelling capacity (FSC) studies showed that the hydrogels have fast swelling properties and that they reached equilibrium after 1 h. Furthermore, all the hydrogels were sensitive to the increasing salt concentrations and pH of the medium. Both AUL and FSC reduced in saline solution while their values increased in alkaline buffer solutions. The result indicate that the difunctional carboxylic acids produced hydrogels with stronger material functions compared with the polyfunctional carboxylic acid and the order of increases in both AUL and FSC was CASXBTC, CASXPIM, CASXSUB and CASXGLU.     

GC-MS quantitation of benzoic and aralkyl carboxylic acids as their trimethylsilyl derivatives: In model solution I

Summary This paper describes the fragmentation patterns and the GC-MS quantitation possibilities of the trimethylsilyl derivatives of thirty-one aromatic carboxylic acids, using ion trap detection (ITD). Sixteen aralkyl carboxylic acids, including those containing a saturated aliphatic side chain {phenylacetic, 2-phenylbutyric, phenylglycolic (mandelic acid), β-phenyllactic, 3-hydroxyphenylacetic, β-phenylpyruvic and 3-(4-hydroxyphenyl)-propionic acids} and those with an unsaturated aliphatic side chain {cinnamic, 2-hydroxycinnamic (o-coumaric), 4-methoxycinnamic, 3-hydroxycinnamic (m-coumaric), 4-hydroxycinnamic (p-coumaric), 4-hydroxy-3-methoxycinnamic (ferulic acid), 3,4-dihydroxycinnamic (caffeic), and 4-dihydroxy-3,5-dimethoxycinnamic (sinapic) acids}, as well as, the fifteen hydroxy(methoxy) benzoic acids {benzoic, 2-hydroxybenzoic (salicylic), 3-hydroxybenzoic, 4-hydroxybenzoic, 3,5-dimethoxybenzoic, 3,4-dimethoxybenzoic (veratric), 2,6-dihydroxybenzoic (γ-resorcylic), 3-methoxy-4-hydroxybenzoic (vanillic), 2,5-dihydroxybenzoic (gentisic), 2,4-dihydroxybenzoic (β-resorcylic), 3,4-dihydroxybenzoic (protocatechuic), 3,5-dihydroxybenzoic (α-resorcylic), 2,4,5-trimethoxybenzoic (asaronic), 3,5-dimethoxy-4-hydroxybenzoic (syringic) and 3,4,5-trihydroxybenzoic (gallic) acids}, provided distinct fragmentation characteristics that were very useful for their identification and simultaneously quantitation. Based on 1–20 ng amounts of acids, very informative ions of high mass with considerable intensities ([M+TMS]⁺, [M+1]⁺), , ([M−CH₃]⁺) were obtained. In the case of the cinnamic acid derivatives, several odd electron fragments are formed by the loss of CO, HCHO and/or Si(CH₃)₄ molecules. In the case of benzoic acids the molecular ion proved to be abundant in three, the [M−CH₃]⁺ ion in nine cases out of fifteen. The special MacLafferty rearrangement product ([C₆H₅Si(CH₃)₂]⁺) was obtained in different yields. In addition to the TIC values, at least three, and in most cases four, selective fragment ions could be utilized for quantitation. The reproducibility of the data in the concentration range of 1–20 ng acids proved to be between 1.2 and 13.0% (R.S.D.). Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997     

Cyclic mechanism in the trapping of carbonyl oxides with alcohols and carboxylic acids

The reaction of diphenylcarbonyl oxide with alcohols and carboxylic acids, which has been classified as a nucleophilic trapping, is shown to be in the reactivity order: AcOH ? MeOH > CF₃CH₂OH > EtOH ? t-BuOH. A laser-flash spectroscopy indicated that the reaction of carboxylic acids is very fast, that is, one-tenth of the diffusion rate. These results suggest that the hydroxyl compounds react as an acid and a nucleophile at the same time and the major reaction is via the seven- and five-membered cyclic mechanism for RCO₂H and ROH, respectively.     

Coupled diffusion of weakly ionized polyelectrolytes. Polyacrylic acids in water

Ternary diffusion coefficients have been measured conductimetrically for polyacrylic acid (90,000 g-mol^–1) + polyacrylic acid (5,000 g-mol^–1) + water at 25°C. Binary diffusion coefficients for each fraction of polyacrylic acid have also been measured. The conductimetric results support previously reported Gouy optical data that indicated strong coupling between the diffusing polyacrylic acids. Although the carboxylic groups are only weakly ionized (pK_a 4.3), each polyacrylate anion carries a substantial electric charge due to the large number of carboxylic groups per polyion. An approximate analysis suggests that the electric field generated by diffusion of the polyacrylate ions with hydrogen counterions is responsible for the strongly coupled diffusion. The theory provides an explanation for the previously reported experimental results that indicate heavier fractions of polyacrylic acid can diffuse more rapidly than lighter fractions. To help interpret the polyacrylic acid data, ternary diffusion coefficients have also been measured for n-butyric acid + acetic acid + water. The diffusion of the monocarboxylic acids is weakly coupled.     

Metal ions recovery with alginic acid coupled to ultrafiltration membrane

Alginic acid (AA) is a natural polysaccharide derived from brown algae. Naturally AA is present in cellular wall forming insoluble complexes with ions as calcium, magnesium, and sodium. This polymer is composed of uronic acids as d-manuronic acid and l-guloronic acid (units differing in C5 configuration) which are disposed in blocks or alternating on principal chain due its spatial configuration. In its structure only hydroxy and carboxylic acid are present, with a pK_{a alginic acid} = 3.45. At pH = 4.3 this polymer is completely soluble in water. Metal ion retention was evaluated using liquid-phase polymer-based retention (LPR) technique elution method, and metal ions studied were Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ at different pH and filtration factor. A high efficiency for all metal ions at all pH was reveled with a maximum at pH = 4.5 of 100% of majority of metal ions. To evaluate the maximum retention capacity (MRC) of AA, LPR technique concentration method was used. Metal ion/polymer ratio from 48 to 325 mg/g for Zn²⁺ and Ag⁺ were studied, respectively. Homopolymer and polymer-metal ion complexes were characterized using FT-IR, Far-IR spectroscopy, dynamic light scattering (DLS), and thermogravimetric analysis. FT-IR revealed relevant shifts between AA and PMC, which involve carboxylic acid, hydroxy, and ether groups. DLS shows non-pH-dependent sizes of alginic acid-silver complexes.     

Tunable separation of anions and cations by column switching in ion chromatography

A convenient ion chromatography method has been proposed for the routine and simple determination of anions (Cl⁻, SO₄²⁻ and NO₃⁻) and/or cations (Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via two 6-port switching valves or a single 10-port valve. The connection order of the ion-exchange columns could be varied by switching the valve(s). The present system therefore allowed the separation of either cations or anions in a single chromatographic run. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When 2.4 mM 5-sulfosalicylic acid was used as the eluent, the three anions and the five cations could be separated on the anion-exchange column and cation-exchange column, respectively. In order to obtain the separations of the target ions, the injection valve was placed between the two columns. Complete separations of the above anions or cations were demonstrated within 10 min each. The detection limits at S/N = 3 were 19-50 ppb (μg/l) for cations and 10-14 ppb for anions. The relative standard deviations of the analyte ions were less than 1.1, 2.9 and 2.8% for retention time, peak area and peak height, respectively. This proposed technique was applied to the determination of common anions and cations in river water samples.     

Friedel-Crafts acylation reaction using carboxylic acids as acylating agents

Dehydrative Friedel-Crafts acylation reaction of aromatic compounds with carboxylic acids as acylating agents was investigated in the presence of Lewis acid- or Brønsted acid-catalyst. Various metal triflates and bis(trifluoromethanesulfonyl)amides showed catalytic activity at high temperature, among which Eu(NTf₂)₃ proved to be the most effective and efficiently catalyzed the acylation reaction of alkyl- and alkoxybenzenes with aliphatic and aromatic carboxylic acids at 250 °C. Bi(NTf₂)₃ was more effective than Eu(NTf₂)₃ at lower temperature, but proved to be hydrolyzed in the presence of a small amount of water to give HNTf₂ and [Bi₆O₄(OH)₄(H₂O)₆](NTf₂)₆. The structure of the latter compound was confirmed by a single crystal X-ray analysis. Among five Brønsted acids, HOTf, HNTf₂, HCTf₃, TsOH, and Nafion^® SAC-13, HNTf₂ has proved to be the most efficient catalyst and more effective than Eu(NTf₂)₃ for the acylation of p-xylene with heptanoic acid at 220 °C or lower temperature. HNTf₂ catalyzed the acylation of anisole with carboxylic acids in high yields in refluxing toluene with azeotropic removal of water.     

Fractionation analysis of manganese and zinc in beers by means of two sorbent column system and flame atomic absorption spectrometry

In the present article, a method of operational fractionation of Mn and Zn in beer using flame atomic absorption spectrometry was developed. The proposed fractionation scheme was based on use of a hydrophobic adsorbing resin Amberlite XAD7 (first column, 2 g resin bed) connected in a series with a strong cation exchanger Dowex 50Wx4 (second column, 1 g resin bed). After passing the samples of beers through the columns, distinct groupings of Mn and Zn species retained on the sorbents, i.e., hydrophobic fraction of polyphenols bound metal species and cationic metal species fraction, respectively, were determined in respective eluates obtained after complete recovery of Mn and Zn species with 10 ml of 2.0 mol l⁻¹ HNO₃ (first column) and 10 ml of 4.0 mol l⁻¹ HCl (second column). In addition, the effluents collected were analyzed prior to the evaluation of the third, residual fraction, presumably attributed to any hydrophilic anionic and inert metal species. The established fractionation patterns for Mn and Zn were discussed in reference to likely associations of metals with endogenous food bioligands and possible availability of the distinguished metal species classes. The quality of the results was proved by the recovery experiments.     

Determination of uranium and thorium in complex samples using chromatographic separation, ICP-MS and spectrophotometric detection

The paper describes a research of possible application of UTEVA and TRU resins and anion exchanger AMBERLITE CG-400 in nitrate form for the isolation of uranium and thorium from natural samples. The results of determination of distribution coefficient have shown that uranium and thorium bind on TRU and UTEVA resins from the solutions of nitric and hydrochloric acids, and binding strength increases proportionally to increase the concentration of acids. Uranium and thorium bind rather strongly to TRU resin from the nitric acid in concentration ranging from 0.5 to 5 mol L⁻¹, while large quantities of other ions present in the sample do not influence on the binding strength. Due to the difference in binding strength in HCl and HNO₃ respectively, uranium and thorium can be easily separated from each other on the columns filled with TRU resin. Furthermore, thorium binds to anion exchanger in nitrate form from alcohol solutions of nitric acid very strongly, while uranium does not, so they can be easily separated. Based on these results, we have created the procedures of preconcentration and separation of uranium and thorium from the soil, drinking water and seawater samples by using TRU and UTEVA resins and strong base anion exchangers in nitrate form. In one of the procedures, uranium and thorium bind directly from the samples of drinking water and seawater on the column filled with TRU resin from 0.5 mol L⁻¹ HNO₃ in a water sample. After binding, thorium is separated from uranium with 0.5 mol L⁻¹ HCl, and uranium is eluted with deionised water. By applying the described procedure, it is possible to achieve the concentration factor of over 1000 for the column filled with 1 g of resin and splashed with 2 L of the sample. Spectrophotometric determination with Arsenazo III, with this concentration factor results in detection limits below 1 μg L⁻¹ for uranium and thorium. In the second procedure, uranium and thorium are isolated from the soil samples with TRU resin, while they are separated from each other on the column filled with anion exchanger in alcohol solutions. Anion exchanger combined with alcohol solutions enables isolation of thorium from soil samples and its separation from a wide range of elements, as well as spectrophotometric determination, ICP-MS determination, and other determination techniques.     

Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin

In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.     

Chromium(III, VI) speciation analysis with preconcentration on a maleic acid-functionalized XAD sorbent

Chromium may exist in environmental waters as Cr(III) and Cr(IV), the latter being the toxic and carcinogenic form. Since atomic absorption spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry can only yield information on total Cr concentration, a polymer resin bearing O,O-donor chelating groups such as the maleic acid-functionalized XAD(CO)CHCHCOOH resin was synthesized to selectively retain Cr(III) at pH 4.0-5.5. The dynamic breakthrough capacity of the resin for Cr(III) at pH 5.0 was 7.52 mg g⁻¹, and the preconcentration factor extended to 250-300. Chromium(III) in the presence of 250-fold Cr(VI)—which was not retained—could be effectively preconcentrated on the NH₄⁺-form of the resin and determined by AAS or diphenylcarbazide (DPC) spectrophotometry. When Cr(VI) was reduced to Cr(III) with Na₂SO₃ solution brought to pH 1 by the addition of 1 M H₂SO₄, and preconcentrated on the resin, total Cr could be determined. The developed method was validated with a blended coal sample CRM-1632. Since the adsorption behavior as a function of pH of possible interferent metal ions, e.g. Ni(II), Co(II), Cu(II), Cd(II), Zn(II), Pb(II) and Fe(III), was similar to that of Cr(III), selective elution of Cr(III) from the resin was realized using a mixture of 1 wt.% H₂O₂+1 M NH₃. The eluate containing Cr as chromate could be directly analyzed by diphenyl carbazide spectrophotometry without any adverse effect from the common interferents of this method, i.e. Fe(III), Cu(II) Hg(II), VO₃⁻, MoO₄²⁻ and WO₄²⁻. Various synthetic waste solutions typical of electroplating bath effluents containing Cr, Cu, Ni, Zn, Na, Ca, cyanide (and chemical oxidation demand (COD), achieved by glucose addition) were subjected to pretreatment procedures such as hypochlorite oxidation (of cyanide) and catalytic oxidation (of COD) with peroxodisulfate. Chromium determination gave satisfactory results. The combined column preconcentration—selective elution—diphenylcarbazide spectrophotometric determination was also successfully applied to the determination of Cr in artificial and real seawater.