Abstract  The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water.

Abstract  An enrichment-separation procedure basedn the coprecipitationf gold(III), palladium(II) and lead(II)ons with nickel(II)-5-methyl-4-(2-thiazolylazo) resorcinol complex has beeneveloped. The analytical parametersncluding pH, amountsf 5-methyl-4-(2-thiazolylazo) resorcinol, sample volume, etc. wasnvestigated for quantitative recoveriesf Au(III), Pd(II) and Pb(II). Interferenceue to various cations and anions has also beennvestigated. Theetection limits for analyteons by 3sigma were 2.6 microg L(-1) for lead, 1.5 microg L(-1) for gold, 2.1 microg L(-1) for palladium. The accuracyf the method was evaluated by the analysisf certified reference materials (NIST SRM 2711 Montana soil, GBW 07309 Stream sediment). The proposed procedure was successfully applied to environmental samples for theeterminationsf analytes.

Abstract  Bambusae Caulis in Liquamen (BCL) is the distilled product of the condensation from the burning of Phyllostachys nigra var. henosis (Gramineae). The activity-guided isolation of BCL yielded four phenolic compounds: 2,6-dimethoxyphenol (1), 1,2-dihydroxybenzene (2), 1,3-dihydroxybenzene (3) and 1,2-dibenzenecarboxylic acid (4). We evaluated the anti-oxidative, anti-inflammatory and whitening effects of these compounds, via assays, of 1,1-diphenyl-2-picrylhydazyl (DPPH) radical scavenging activity and inhibition of nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 macrophage cells as well as inhibition of tyrosinase activity and melanin production in B16F10 melanoma cells. The results showed that 2 and 3 exhibited significant DPPH radical scavenging activity as well as inhibitory effects on NO production, tyrosinase activity and melanin production. These results suggested that BCL and compounds 2 and 3 can be developed as anti-oxidative, anti-inflammatory and whitening ingredients.

Abstract  Groups of 6-week-old male Syrian golden hamsters were given 13 different phenolic compounds for 20 weeks. Of these compounds, 2(3)-tert-butyl-4-methoxyphenol (BHA), 2-tert-butyl-4-methylphenol (TBMP) and p-tert-butylphenol (PTBP) strongly induced hyperplasia and tumorous lesions in the forestomach. Catechol, p-methylphenol (PMYP), p-methoxyphenol (PMOP), caffeic acid, methylhydroquinone (MHQ) and pyrogallol were less active, and resorcinol, hydroquinone, propylparabene and tert-butylhydroquinone (TBHQ) were not active. The labelling index in the forestomach epithelium was significantly increased by addition to the diet of BHA, TBMP, catechol, PMOP, PTBP and MHQ. PMOP induced epithelial damage and regenerative hyperplasia of the pyloric region. Catechol, caffeic acid and PMYP induced similar though less marked lesions. The labelling index in the glandular stomach was significantly increased by oral catechol (P less than 0.05) or PMOP (P less than 0.05). No histopathological lesions were observed in the urinary bladder epithelium, but propylparabene (P less than 0.05), catechol, TBHQ and MHQ increased the labeling index. These findings indicate that PTBP and TBMP may be carcinogenic for hamster forestomach after long-term administration, and that both one hydroxy and tert-butyl substituents may be important for induction of hamster forestomach tumors.

Abstract  #Modifying effects of the environmental contaminant catechol, and its isomers resorcinol and hydroquinone, on methyl-N-amylnitrosamine (MNAN)-induced carcinogenesis were studied in male F344 rats. Groups of 15 rats were given three i.p. injections of 25 mg/kg of body weight of MNAN within the initial 2-wk period, and commencing 1 wk thereafter they were administered 0.8% catechol, 0.8% resorcinol, or 0.8% hydroquinone in powdered basal diet or were given basal diet alone for 49 wk. Additional groups of 10 to 15 rats were similarly treated without prior carcinogen exposure. Histological examination after sacrifice at wk 52 revealed that the incidences of tongue papillomas and esophageal squamous cell carcinomas in the groups given MNAN followed by catechol (57.1% and 64.3%) or resorcinol (50% and 58.8%) were significantly higher than those in the carcinogen only controls (9.1, and 0%, respectively). Hydroquinone also enhanced the development of esophageal squamous cell carcinomas but was less active than catechol or resorcinol. The incidence of alveolar hyperplasia in the lungs of the group given MNAN followed by catechol (0%) was, in contrast, significantly reduced as compared to the control value (54.5%). Hydroquinone and resorcinol showed a similar but nonsignificant tendency. These results indicated that the environmental contaminant, catechol and its isomers, may play a role in the development of human upper gastrointestinal cancer, in addition to exerting modifying effects in other organs.

Abstract  It was found that the weak chemiluminescence produced from the reaction of polyhydroxy phenols with luminol in alkaline solution could be strongly enhanced by ferricyanide and ferrocyanide. Based on this found, a new flow injection chemiluminescence method is proposed for the determination of four polyhydroxy phenols: pyrogallol, phlorglucinol, quinol and resorcinol. The detection limits of the method are 0.03 mug ml(-1) pyrogallol, 0.03 mug ml(-1) phlorglucinol, 0.04 mug ml(-1) quinol, and 0.02 mug ml(-1) resorcinol. The possible mechanism of CL reactions is also discussed briefly.

Abstract  Nanoparticles of NaAlH(4) have been infiltrated in nanoporous carbon aerogel with TiCl(3) nanoparticles in order to explore possible synergetic effects between nanoconfinement and a functionalized catalytic scaffold. Resorcinol formaldehyde carbon aerogels with an average pore size of 17 nm and total pore volume of 1.26 mL/g were infiltrated with TiCl(3) to obtain an aerogel doped with 3.0 wt % TiCl(3) nanoparticles. NaAlH(4) was melt-infiltrated into the functionalized carbon aerogel at 189 °C and p(H(2)) ∼ 186-199 bar. Energy-dispersive spectrometry (EDS) combined with focused ion beam (FIB) techniques revealed the presence of Na, Al, Ti, and Cl inside the aerogel scaffold material. The infiltrated NaAlH(4) was X-ray amorphous, whereas (27)Al magic-angle spinning (MAS) NMR spectroscopy confirmed the presence of nanoconfined NaAlH(4). Temperature-programmed desorption mass spectroscopy (TPD-MS) and Sieverts' measurements demonstrated significantly improved hydrogen desorption kinetics for this new nanoconfined NaAlH(4)-TiCl(3) material as compared to nanoconfined NaAlH(4) without the catalysts TiCl(3) and to bulk ball-milled samples of NaAlH(4)-TiCl(3). We find that the onset temperature for hydrogen release was close to room temperature (T(onset) = 33 °C), and the hydrogen release rate reached a maximum value at 125 °C, which demonstrates favorable synergetic effects between nanoconfinement and catalyst addition.

Abstract  Acrolein, four methacrylates, two guanidine compounds and resorcinol were tested for embryotoxicity on three day chicken embryos. The most potent chemical was acrolein, with the ED50 0.05 mumol per egg for the total effect, including deaths and malformations. The substances next in potency were N,N'-di-o-tolyl-guanidine and N,N-diphenylguanidine, with ED50 values 0.17 and 0.20 mumol per egg, respectively. Resorcinol and the methacrylates had ED50 values ranging from 2.4 to 22.0 mumol per egg. Acrolein, diphenylguanidine, tetrahydrofururylmethacrylate and trimethylolpropanetrimethacrylate caused the largest amounts of malformed embryos.

Abstract  We developed a method to analyze airborne lead concentrations in the field. It was a modification of the colorimetric method using the reaction between 4(2-pyridylazo)-resorcinol (PAR) and lead with cyanex302 in an acid medium to reduce interfering metals. The lead concentration was detected with a photometer made in Thailand. The developed method uses an impinger containing 1% nitric acid solution as an absorbing agent to collect airborne lead at a flow rate of less than or equal to one liter/minute. Cyanex302 solution in toluene was used to extract metals from the samples and 0.1M nitric acid was used to extract just lead. The lead solution was reacted in 0.5 ml of 0.03% PAR solution, with 1 ml ammonium chloride buffer; the absorption of this solution was measured by a photometer. The results show the limit of detection (LOD) was 0.01 mg/l. The limit of quantification (LOQ) was 0.03 mg/l. The percent recovery of the lead concentrations of 0.05 - 3.0 mg/l was 94.0 to 103.5%. The precision presented as %CV ranged from 0.65 to 10.27%. Lead concentration in a lead smelting factory detected by this method was not significantly different from that detected by the NIOSH method: 7,303 at a 95% confidence level.

Abstract  A sensitive, selective and simple post-column chemiluminescence (CL) detection method for simultaneously determining catechol, resorcinol, hydroquinone has been developed based on high performance liquid chromatography (HPLC) coupled with CL detection using reaction of dihydroxybenzenes with acidified potassium permanganate solution with the enhancing effect of formic acid. The optimal conditions for the CL detection and HPLC separation were achieved. Dihydroxybenzene isomers were baseline separated at column temperature of 25 degrees C using a mobile phase of methanol-0.1 mmol/L beta-cyclodextrin aqueous solution (30/70, v/v) with an isocratic elution program and the mobile phase matched well the CL detection. For all compounds, the linear ranges of the CL detection were about two orders of magnitude. The detection limits were 3.2 microg/L for hydroquinone, 4.7 microg/L for resorcinol and 5.2 microg/L for catechol. Combining with solid phase extraction, the proposed method was successfully applied to the determination of dihydroxybenzenes in river water. The recoveries for the three dihydroxybenzenes were 92.1%-95.4%.

Abstract  It is shown that alcohol-water mixtures (e.g., 43 wt% ethanol) provide a suitable medium for the efficient production in high yield of beta-hematin from ferriprotoporphyrin IX (FP), as measured by infrared spectroscopy. Previous and present light-absorption data of FP, obtained under specific acid conditions in an ethanol-water medium, suggest the presence of FP monomers, which are considered to promote the reaction leading to beta-hematin. Other aspects of the mechanism of reaction are discussed.

Abstract  An improved spectrophotometric determination of uranium(VI) is proposed using 4-(2-pyridylazo)resorcinol(PAR) in the presence of benzyldimethylstearyltrimethylammonium chloride(BSTAC) as a cationic surfactant. The calibration graph is linear in the range of 0.3-60 microg/10 ml uranium(VI), measuring the absorbance at 550 nm. The reproducibility for 19.0 microg/10 ml uranium(VI) is 0.57%. The third-derivative method using the third-derivative distance (d(3)A/dlambda(3)) among lambda(1) 530 nm, lambda(3) 594 nm and lambda(2) 565 nm was also investigated.

Abstract  The chronic toxicity of 2,4-toluenediamine (2,4-TDA) alone or in conbination with a hair dye complex (2,5-toluenediamine, p-phenylenediamine, and resorcinol) was studied in Swiss-Webster mice of both sexes by a skin-painting technique. The predominant neoplasms seen in these mice were primary pulmonary adenomas and adenocarcinomas. Skin neoplasms were seen in most groups of mice, including untreated control mice. Statistical analysis of the incidences of skin neoplasms among the various groups of mice did not show any significant differences. The 2,4-TDA alone or mixed with the hair dye complex did not produce any abnormal proliferation and maturation of the squamous epithelium of the skin. The 2,4-TDA under our experimental conditions was found to be nontoxic and noncarcinogenic to the skin of mice.

Abstract  Flavonoids are widely distributed in plant-derived foods and possess a variety of biological activities including antithyroid effects in experimental animals and humans. A structure-activity study of 13 commonly consumed flavonoids was conducted to evaluate inhibition of thyroid peroxidase (TPO), the enzyme that catalyzes thyroid hormone biosynthesis. Most flavonoids tested were potent inhibitors of TPO, with IC50 values ranging from 0.6 to 41 microM. Inhibition by the more potent compounds, fisetin, kaempferol, naringenin, and quercetin, which contain a resorcinol moiety, was consistent with mechanism-based inactivation of TPO as previously observed for resorcinol and derivatives. Other flavonoids inhibited TPO by different mechanisms, such as myricetin and naringin, showed noncompetitive inhibition of tyrosine iodination with respect to iodine ion and linear mixed-type inhibition with respect to hydrogen peroxide. In contrast, biochanin A was found to be an alternate substrate for iodination. The major product, 6,8-diiodo-biochanin A, was characterized by electrospray mass spectrometry and 1H-NMR. These inhibitory mechanisms for flavonoids are consistent with the antithyroid effects observed in experimental animals and, further, predict differences in hazards for antithyroid effects in humans consuming dietary flavonoids. In vivo, suicide substrate inhibition, which could be reversed only by de novo protein synthesis, would be long-lasting. However, the effects of reversible binding inhibitors and alternate substrates would be temporary due to attenuation by metabolism and excretion. The central role of hormonal regulation in growth and proliferation of thyroid tissue suggests that chronic consumption of flavonoids, especially suicide substrates, could play a role in the etiology of thyroid cancer.

Abstract  Vertical replication for TEM is ideal for studying non-periodic specimens from 0.7 to 3 nm, a resolution mid-range difficult to attain by any other technique. This paper discusses the importance of vertical replication, its methods and hardware for high-resolution TEM. Evidence from diverse published research will demonstrate vertical replication's versatility in imaging the molecular level normally unattainable in freeze-dried polymers, polyethylene tribological wear on surfaces, low-density polymer networks or biological gels. Vertical platinum-carbon (Pt-C) replication minimizes the horizontal movement of Pt-C on a surface. Surface objects are symmetrically enlarged by a vertically deposited Pt-C film. To estimate real size in replicas, 16-25 particles or filaments need to be measured in calibrated transmission electron microscopy (TEM) images and reduced by a value less than the Pt-C film thickness measured with a quartz monitor. Continuous, vertically deposited Pt-C films are formed on mica at a deposition thickness of around 1.0 nm and on silver at a thickness of 0.4-0.5 nm. The distance between helical turns in poly(1-tetradecene sulfone) of 0.7 nm is the highest resolution achieved with vertical replication. Two polysulfones freeze-dried and vertically replicated on mica contained structures are predicted by indirect physical chemical methods to be present in solution. Polymer chains are fully Pt-C coated, with no uncoated gaps along chains. Some side-chains on the extended non-helical poly(1-tetradecene sulfone) are also detected. To estimate the real chain width, polymer chains measured in images are reduced by the Pt-C film thickness minus 0.5 nm. The polymer chain widths estimated from molecular models are in the same range of widths as those measured using the image size correction method. Also, it is possible to distinguish random coil proteins (chain width of around 0.5 nm) from an alpha-helix (chain diameter of about 1 nm) in vertically replicated samples on silver substrates. In the future, subnanometer resolutions below 0.7 nm should be possible. The resolution of vertical replication depends on the thickness of a continuous, amorphous Pt-C film. That thin, continuous 0.4-0.5 nm Pt-C films on silver substrates can be made suggests that a point-to-point resolution limit of around 0.28 nm in TEM may ultimately be approachable with replication.

Abstract  BACKGROUND: In 1977, the use of Gelatine-Resorcine-Formaline (GRF) biological glue during surgery of acute Type A aortic dissection was proposed. The present study retrospectively analyzes the late results obtained with this adjunct in an experience extending over a twenty-year period of time.

PATIENTS AND METHODS: From January 1977 to March 1996, 171 patients (124 males and 47 females) aged from 15-79 years (mean age: 53 +/- 14 years) underwent an emergency operation for type A aortic dissection in our institution. All patients suffered from acute type A dissection and 144 (84%) were operated on within 48 hours after the onset of symptoms. Twenty-six patients (15.2%) had Marfan's syndrome. The ascending aorta was replaced in all patients and the aortic stumps were reinforced with the GRF glue. In 39 patients (23%), the aortic valve was replaced either independently (5 cases, 3%) or by means of a composite graft (34 cases, 19.8%). Because of the location of the intimal tear, the aortic replacement was extended to the transverse arch in 58 patients (33.9%).

RESULTS: Hospital mortality amounts to 21% (36 patients), 22.8% in patients with arch replacement and 21.1% in patients without arch replacement (n.s). One hundred thirty-five patients were discharged and surveyed from 2 months to 19 years postoperatively (cumulative follow-up: 856 patients/years. Mean follow-up: 79 +/- 66 months). During this period of time, 22 patients (16.1%) had to be reoperated on for a total of 28 reoperations. Six of those (27.2%) died at reoperation. At univariate analysis, presence of Marfan's syndrome (p < 0.05) and absence of arch replacement (p < 0.02) were determinant risk factors for reoperation. Emergency (p < 0.01) and thoracoabdominal replacement (p < 0.04) were determinant risk factors of death at reoperation. The acturial freedom from reoperation (Kaplan-Meier, CI: 95%) is: 96.08% (90.9-98.2), 87.6% (79.8-92.7), 80.9% (70.8-86.1), 66.4% (51.1-78.9) at 1, 5, 10, and 15 years respectively. A total of 36 patients (27.7%) died during follow-up. Presence of Marfan's syndrome (p < 0.01), reoperation (p < 0.02), stroke (p < 0.05), cardiac failure (p < 0.05) were determinant risk factors of late mortality. The actuarial late survival rate (K-M. C.I.: 95%), including hospital mortality, is: 71.5% (64.3-77.8), 66% (58.3-73), 56.4% (47.7-64.7), 46.3% (36.4-56.5) at 1, 10 and 15 years.

CONCLUSIONS: The GRF glue has proved to be extremely useful during emergency initial surgery for acute type A dissection, making the procedure much easier and safer. Through this operative improvement, the use of the GRF glue seems to have a beneficial influence on the late results which however, depend mainly on the patient's basic condition.

Abstract  A new micelle-mediated separation and preconcentration method was developed for ultra-trace quantities of mercury ions prior to spectrophotometric determination. The method is based on cloud point extraction (CPE) of Hg(II) ions with polyethylene glycol tert-octylphenyl ether (Triton X-114) in the presence of chelating agents such as 1-(2-pyridylazo)-2-naphthol (PAN) and 4-(2-thiazolylazo) resorcinol (TAR). Hg(II) ions react with both PAN and TAR in a surfactant solution yielding a hydrophobic complex at pH 9.0 and 8.0, respectively. The phase separation was accomplished by centrifugation for 5 min at 3500 rpm. The calibration graphs obtained from Hg(II)-PAN and Hg(II)-TAR complexes were linear in the concentration ranges of 10-1000 μg L(-1) and 50-2500 μg L(-1) with detection limits of 1.65 and 14.5 μg L(-1), respectively. The relative standard deviations (RSDs) were 1.85% and 2.35% in determinations of 25 and 250 μg L(-1) Hg(II), respectively. The interference effect of several ions were studied and seen commonly present ions in water samples had no significantly effect on determination of Hg(II). The developed methods were successfully applied to determine mercury concentrations in environmental water samples. The accuracy and validity of the proposed methods were tested by means of five replicate analyses of the certified standard materials such as QC Metal LL3 (VWR, drinking water) and IAEA W-4 (NIST, simulated fresh water).

Abstract  Medical case reports published in the 20th century over the course of several decades show that resorcinol caused reversible adverse effects on the human thyroid gland (TG) manifested as hypothyroidism. Affected patients had ulcerating leg varicosities and underwent prolonged treatment with ointments containing high concentrations of resorcinol. In animal studies resorcinol failed to induce TG toxicity, unless pharmacokinetic/toxicokinetic (PK/TK) conditions were manipulated (e.g., injection of resorcinol in oil or application in a slow release formulation). A recently completed two-generation reproductive toxicity study in rats did not detect any adverse effects on either reproductive or TG end points (Welsch, Nemec, and Lawrence, 2008, Int. J. Toxicol. 37, this issue). Resorcinol intake via drinking water up to the palatability limit had resulted in average daily intakes (mg/kg) of 233 in F0 and F1 males and 304 (premating/gestation) or 660 (lactation) in females. Free resorcinol in blood plasma was barely detectable in a few parental animals, indicating rapid metabolism. This short review communication offers a perspective on compromised human skin barrier function as a likely cause of drastic increases in resorcinol absorption. In conjunction with multiple daily applications over many months to hyperemic, inflamed, and lesioned human skin much higher absorption was likely responsible for the reported human TG toxicity.

Abstract  Planar triazinium cationic species from vanadyl-assisted cyclization of 1-(2-thiazolylazo)-2-naphthol (H-TAN, ), 1-(2-pyridylazo)-2-naphthol (H-PAN, ), 2-(2'-thiazolylazo)-p-cresol (H-TAC, ) and 6-(2'-thiazolylazo)-resorcinol (H-TAR, ) were prepared and characterized. A dioxovanadium(v) species [VO(TAR)] () was also isolated. Compounds , and were structurally characterized. Both and have planar structures. Complex has VON coordination geometry. The cyclised triazinium compound forms a radical species within -0.06 to -0.29 V vs. SCE in DMF-0.1 M tetrabutylammonium perchlorate with a second response due to formation of an anionic species. A confocal microscopic study showed higher nuclear uptake for having a fused thiazole moiety than with a fused pyridine ring. The compounds showed a partial intercalative mode of binding to calf thymus DNA. Compound showed plasmid DNA photo-cleavage activity under argon and photocytotoxicity in HeLa and MCF-7 cells with IC values of 15.1 and 3.4 μM respectively in visible light of 400-700 nm, while being essentially non-toxic in the dark with IC values of 90.4 and 21.9 μM. A TDDFT study was done to rationalize the experimental data.

Abstract  We had reported on the basis of experimental findings that the efficacy of protecting the suture line in tracheoplasty by using a self-fascia lata and GRF glue. This time we investigated the effectiveness of GRF glue in the respiratory surgery on the basis of clinical findings. All ten cases in which GRF glue was used resulted in an excellent outcome, namely, GRF glue prevented from air leakage, bleeding and leakage of chyle. Moreover, it was not recognized that any grave side effects occurred in any cases after using GRF glue. We could conclude that GRF glue was a useful material for the respiratory surgery, especially for the case that had a dead space after lobectomy. However its price is not inexpensive, therefore, there seems need to restrict the use of GRF glue--for example--to cases of Giant bulla resection, residual of a large dead space as a postoperative possibility and chemotherapy performed before an operation, and so on.

Abstract  Gelatin-resorcin-formaldehyde glue is now widely used in cardiac surgery, particularly in Europe. A case is reported where its use may have contributed to the pulmonary dysfunction seen postoperatively after elective closure of a postinfarct ventricular septal defect. It is believed that this is a result of a relatively high exposure of the pulmonary circulation to the glue, in particular to formalin. Although not proven, the authors advise caution when using the glue within the cardiac chambers.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. A method for the on-line preconcentration and chromatography of trace metals, e.g., Co, Ni, Cu, Zn, Cd and Pb, on N,N,N',N'-tera(2-aminoethyl)ethylenediamine-bonded silica is described. The preconcentrated metals were desorbed with 0.13 M tartrate, which allows direct separation on a cation-exchange chromatographic column. The metals separated were detected by postcolumn reaction with 4-(2-pyridylazo)resorcinol and measuring the absorbances at 500 nm. Linear calibrations graphs were obtained ove the range 1ynthesis and characteristics of the chelated silica are described. The method was applied to the analysis of river and interstitial sediment waters.

Abstract  The uranyl ion forms only 1:1 chelates with 4-(2-thiazolylazo) resorcinol (TAR) in solution, UO(2)(TAR)H(+) being formed below pH 3 and UOS(TAR) above pH 3-5. The latter complex may also be precipitated at pH > 3. The quantitative formation of UO(2)(TAR) at pH 7.5-7.8 in solutions containing a small excess of reagent and some triethanolamine as buffer can be used for the sensitive spectrophotometric determination of uranium. Several interfering ions can be masked with a mixture of sodium fluoride, cyclohexanediaminetetraacetic acid and 5-sulphosalicylic acid. TAR is slightly less sensitive than 4-(2-pyridylazo)resorcinol as a reagent for uranium but is more selective.

Abstract  Organic solvent-free mobile-phase systems in ion-pair reversed-phase partition high-performance liquid chromatography (IPRP-HPLC) are demonstrated; using urea at 3.0 - 7.0 molal (mol kg(-1)) as a modifier in a mobile phase on an octadecylsilanized silica column, four nitrophenolates and metal 4-(2-pyridilazo)resorcinol (PAR) chelates (in PAR chelates system an aqueous mobile phase with 15 wt% methanol was used) were separated rapidly within 6 min at no sacrifice to the separation efficiency. On the addition of urea in the mobile phase, reduced retention times of nitrophenolates and naphthalenesulfonates and also diminution of the height equivalent to a theoretical plate were observed. The addition of urea and guanidium chloride (GuCl) in the mobile phase gave rise to a decrease in the mobile phase volume; in turn, this meant an increased volume of the stationary phase. As the concentration of urea and GuCl in the mobile phase increased, the volume of the mobile phase in the column decreased within about 70% and 40% at 7.0 molal of urea and GuCl, respectively. A decrease in the mobile phase volume suggests an increase in the extent of solvation of the bonded hydrocarbon chain of the stationary phase. The possible explanations for the LC behavior with the urea and GuCl are turned into reduction of hydrophobic interaction in LC processes, solute partitioning and entangling of alkyl chain brushes, with the addition of urea. The water structure breakers, urea and GuCl, most likely affect the solvation states of both solute molecules and the hydrocarboneous stationary phase by changing the nature of the water solvent, which provides a new technique for fine tuning of the LC resolution of the analytes.