TCA Concentrations Research Articles

Optimal Concentration of 2,2,2-Trichloroacetic Acid for Protein Precipitation Based on Response Surface Methodology.

For low protein concentrations containing biological samples (in proteomics) and for non proteinaceous compound assays (in bioanalysis), there is a critical need for a simple, fast, and cost-effective protein enrichment or precipitation method. However, 2,2,2-trichloroacetic acid (TCA) is traditionally used for protein precipitation at ineffective concentrations for very low protein containing samples. It is hypothesized that response surface methodology, can be used to systematically identify the optimal TCA concentration for protein precipitation in a wider concentration range. To test this hypothesis, a central composite design is used to assess the effects of two factors (X1 = volume of aqueous solution of protein, and X2 = volume of TCA solution 6.1N) on the optical absorbance of the supernatant (Y1), and the percentage of protein precipitated (Y2). Using either bovine serum albumin (BSA) as a model protein or human urine (with 20 ppm protein content), 4% w/v (a saddle point) is the optimal concentration of the TCA solution for protein precipitation that is visualized by SDS-PAGE analysis. At this optimal concentration, the Y2-values range from 76.26 to 92.67% w/w for 0.016 to 2 mg/mL of BSA solution. It is also useful for protein enrichment and xenobiotic analysis in protein-free supernatant as applied to tenofovir (a model HIV microbicide). In these conditions, the limit of detection and limit of quantitation of tenofovir are respectively 0.0014 mg/mL and 0.0042 mg/mL. This optimal concentration of TCA provides optimal condition for protein purification and analysis of any xenobiotic compound like tenofovir.

Simultaneous determination of ten taste and odor compounds in drinking water by solid-phase microextraction combined with gas chromatography-mass spectrometry

Taste and odor (T&O) problems in drinking water frequently occur because of many compounds present in the water, of which trans-1,10-dimethyl-trans-9-decalol (geosmin) and 2-methylisoborneol (MIB) are well-known. In this study, a fast and effective method was established for simultaneous determination of 10 T&O compounds, including geosmin, MIB, 2,4,6-trichloroanisole (TCA), 2-methylbenzofuran, 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), cis-3-hexenyl acetate, trans,trans-2,4-heptadienal, trans, cis-2,6-nonadienal, and trans-2-decenal in water samples by headspace solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. An orthogonal array experimental design was used to optimize the effects of SPME fiber, extraction temperature, stirring rate, NaCl content, extraction time, and desorption time. The limits of detection ranged from 0.1 to 73 ng/L were lower than or close to the odor threshold concentrations (OTCs). All the 10 T&O compounds were detected in the 14 water samples including surface water, treatment process water and tap water, taken from a waterworks in Lianyungang City, China. MIB and geosmin were detected in most samples at low concentration. Six T&O compounds (IPMP, IBMP, trans,cis-2,6-nonadienal, 2-methylbenzofuran, trans-2-decenal, and TCA) were effectively decreased in water treatment process (sedimentation and filtration) that is different from cis-3-hexenyl acetate, MIB and geosmin. It is noted that the TCA concentrations at 15.9–122.3 ng/L and the trans,cis-2,6-nonadienal concentrations at 79.9–190.1 ng/L were over 10 times higher than their OTCs in tap water. The variation of the analytes in the all water samples, especially distribution system indicated that distribution system cannot be ignored as a T&O compounds source.

Bile acids induce arrhythmias in human atrial myocardium—implications for altered serum bile acid composition in patients with atrial fibrillation

ObjectiveHigh bile acid serum concentrations have been implicated in cardiac disease, particularly in arrhythmias. Most data originate from in vitro studies and animal models. We tested the hypotheses that (1)...

Effect of Trichloroacetic Acid Hydrogel on Self-Etch Adhesive Bond Strength to Dental Tissues

Trichloroacetic acid (TCA) is a soft tissue cauterizing agent applied to gingival margins prior to cervical tooth-colored restorations. The present in vitro study evaluated the effects of two different concentrations of TCA hydrogel as a hemostatic/preconditioning agent on the shear bond strength (SBS) of a self-etch adhesive to tooth structures. Thirty-six flat enamel and 36 flat dentin surfaces were prepared using human molars; each group was subdivided into three subgroups (n = 12). The groups were made ready as follows: In groups 1 (E1 and D1), the enamel (E) and dentin (D) surfaces were designated as control groups and remained intact. In groups 2 (E2 and D2), 35% TCA gel was applied to enamel and dentin surfaces for 30 seconds. In groups 3 (E3 and D3), 50% TCA gel was applied to enamel and dentin surfaces for 30 seconds. Clearfil SE Bond and Z100 composite resin were applied to the surfaces according to manufacturers' instructions. After 24 hours of incubation and thermocycling, the composite cylinders underwent an SBS test in a DARTEC test machine. Data were analyzed using the ANOVA and Scheffe's test (α=0.05). The mean SBS±SD in the study groups were 34.73±5.66, 35.32±7.3, 23.75±9.67, 20.94±9.84, 19.32±6.20, 23.50±6.63 MPa in the E1, E2, E3, D1, D2 and D3 groups, respectively. ANOVA revealed significant differences between the SBS values of enamel groups (p=0.001). There were no significant differences between the dentin groups (p=0.425). Application of 35 and 50% concentrations of TCA to dentin had no detrimental effect on the bond produced by two-step self-etch adhesive under study; however, application of only 35% TCA to enamel did not result in a detrimental effect on the same adhesive.

Successful full‐scale enhanced anaerobic dechlorination at a NAPL strength 1,1,1‐TCA source area

AbstractBioremediation of 1,1,1‐trichloroethane (TCA) is more challenging than bioremediation of other chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE). TCA transformation often occurs under methanogenic and sulfate‐reducing conditions and is mediated by Dehalobacter. The source area at the project site contains moderately permeable medium sand with a low hydraulic gradient and is approximately 0.5 acre. TCA contamination generally extended to 35 feet, with the highest concentrations at approximately 20 feet. The concentrations then decreased with depth; several wells contained 300 to 600 mg/L of TCA prior to bioremediation. The area of treatment also contained 2 to 30 mg/L of TCE from an upgradient source. Initial site groundwater conditions indicated minimal biotic dechlorination and the presence of up to 20 mg/L of nitrate and 90 mg/L of sulfate. Microcosm testing indicated that TCA dechlorination was inhibited by the site's relatively low pH (5 to 5.5) and high TCA concentration. After the pH was adjusted and TCA concentrations were reduced to less than 35 mg/L (by dilution with site water), dechlorination proceeded rapidly using whey (or slower with sodium lactate) as an electron donor. Throughout the remediation program, increased resistance to TCA inhibition (from 35 to 200 mg/L) was observed as the microbes adapted to the elevated TCA concentrations. The article presents the results of a full‐scale enhanced anaerobic dechlorination recirculation system and the successful efforts to eliminate TCA‐ and pH‐related inhibition. © 2012 Wiley Periodicals, Inc.

Effect of carbon sources on the removal of 1,1,2-Trichloroethane and 1,1,2,2-Tetrachloroethane in UASB reactor

The effect of two carbon sources namely sodium acetate and ethanol was studied in bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactors for the removal of chlorinated ethanes i.e., 1,1,2-Trichloroethane (TCA) and 1,1,2,2-Tetrachloroethane (TeCA) contained in the simulated wastewaters. The Hydraulic Retention Time (HRT) was maintained as 24 hours in all the reactors. The granular biomass in the test reactors R2 and R3 were acclimated to 40 mg/L of TCA and 20 mg/L of TeCA, respectively. The effluent TCA and TeCA concentrations were 0.03 mg/L and 0.18 mg/L, respectively, at the end of acclimation phase. Sodium acetate and ethanol both were found to be suitable as the primary substrates in the biodegradation of TCA and TeCA. However, lower concentrations of the toxic pollutants (TCA and TeCA) were obtained in the effluents with the use of sodium acetate. The COD removal efficiency in the test reactors (R2 and R3) varied in the range of 95 % to 98.2 % accompanied by the formation of 1,2-Dichloroethane (DCA) as the major intermediate.

Hypocalcemia and HypovitaminosisDin Dogs with Induced Endotoxemia

Hypocalcemia is a documented electrolyte disturbance in people and animals with sepsis, but its mechanism is poorly understood. To investigate mechanisms of hypocalcemia in dogs with experimentally induced endotoxemia. Six healthy mixed breed dogs were included in this nonrandomized, placebo-controlled, crossover study. Dogs initially were injected with placebo (0.9% NaCl; 1 mL, IV) and then lipopolysaccharide (LPS; 2 μg/kg, IV) after a 5-day washout period. Blood and urine samples were collected for measurement of serum total calcium (tCa), ionized calcium (iCa), total magnesium (tMg), ionized magnesium (iMg), parathyroid hormone (PTH), 25-hydroxyvitamin D (vitamin D), venous blood gases, and fractional excretion (FE) of calcium. After LPS administration, body temperature increased and blood pressure decreased. Both iCa and tCa decreased (P < .01), but iMg was not significantly different between control and LPS treatments. PTH concentrations increased (P < .01) and vitamin D concentrations decreased (P < .01). Venous pH, bicarbonate, base excess, and blood glucose also decreased (P < .01). Urine tCa concentration was below the limit of detection for all dogs after LPS administration. Hypocalcemia occurs during endotoxemia in dogs and is associated with hypovitaminosis D. Hypomagnesemia, hypoparathyroidism, alkalosis, and increased calciuresis are not associated with hypocalcemia in endotoxemic dogs.

Performance of UASB reactor in the biotreatment of 1,1,2-Trichloroethane

This article aims to examine the performance of bench-scale Upflow Anaerobic Sludge Blanket (UASB) reactor operated under varying operating conditions, during the treatment of simulated wastewater containing 1,1,2-Trichloroethane (TCA). Initially, reactor R1 (control) and reactor R2 (test) containing TCA were operated at 5 different Hydraulic Retention Times (HRTs) of 36, 30, 24, 18 and 12 hours. TCA removal decreased from 99.8% to 96.5%, when the HRT was reduced from 36 to 12 hours in discrete steps. Later, when the OLR was varied periodically from 1.5 to 3.1 kg COD/m3.d to obtain a different substrate: co-substrate ratios; lower TCA removal efficiencies were observed at an OLR of 2.5 kg COD/ m3.d and above. The average effluent concentrations of TCA and COD were 0.12 and 79 mg/L, respectively, at the optimum HRT of 24 hours; whereas the effluent TCA and COD concentrations at the substrate: co-substrate ratio of 50:1 was 0.06 mg/L and 48 mg/L, respectively.

Effect of Dialysate Calcium Concentrations on Parathyroid Hormone and Calcium Balance During a Single Dialysis Session Using Bicarbonate Hemodialysis: A Crossover Clinical Trial

In bicarbonate-based hemodialysis, dialysate total calcium (tCa) concentration may have effects on mineral metabolism. Randomized crossover trial of 3 dialysate tCa concentrations (2.5, 2.75, and 3.0 mEq/L). 22 stable anuric uremic patients underwent three 4-hour bicarbonate hemodialysis sessions with the 3 different dialysate tCa concentrations using a single-pass batch dialysis system. Hourly measurements of plasma water ionized calcium (iCa) and plasma parathyroid hormone (PTH) concentrations. tCa mass balances were measured from the dialysate side. Hourly plasma water iCa concentrations were higher with a dialysate tCa concentration of 3.0 compared with 2.75 and 2.5 mEq/L (P < 0.05), as were iCa concentrations at the end of dialysis sessions (2.66 ± 0.1, 2.56 ± 0.12, and 2.4 ± 0.08 mEq/L, respectively; P < 0.001). Mean tCa mass balance values (diffusion gradient from the dialysate to the patient) were positive with all dialysate tCa concentrations and increased progressively with dialysate tCa concentration (75 ± 122, 182 ± 125, and 293 ± 228 mg, respectively; P < 0.001). Plasma PTH levels increased during dialysis using dialysate tCa concentration of 2.5 mEq/L (mean increase, 225 ± 312 pg/mL) and decreased with dialysate tCa concentrations of 2.75 and 3.0 mEq/L (mean decreases, 68 ± 325 and 99 ± 432 pg/mL, respectively). Small sample size and lack of measurement of total-body calcium mass balances. A dialysate tCa concentration of 2.75 mEq/L might be preferable to 2.5 or 3.0 mEq/L because it is associated with mildly positive tCa mass balance values, plasma water iCa levels in the reference range, and stable PTH levels during dialysis.

Effects of different dialysate calcium concentrations on intradialysis hemodynamic stability

The interplay of correct solute mass balances, such as those of sodium (Na+), potassium (K+) and total calcium (tCa) (Na+MB, K+MB and tCaMB, respectively) with adequate ultrafiltration volumes (VUF) is crucial to achieving hemodynamic stability during hemodialysis (HD). Twenty-two stable anuric uremic patients underwent three 4-hour bicarbonate HD sessions, each with a different dialysate tCa concentration (1.25, 1.375 and 1.50 mmol/L). The GENIUS dialysis system (Fresenius Medical Care, Germany) was used. Volumes of blood and dialysate processed, VUF and dialysate Na+ and K+ concentrations were prescribed to be the same. Hourly measurements of plasma water ionized Ca (Ca++), Na+ and K+ were made, and their trends analyzed. tCaMBs, Na+MBs and K+MBs were determined. Systolic (SBP), diastolic (DBP) blood pressure, mean arterial pressure (MAP) and heart rate (HR) trends during dialysis were analyzed. Mean hourly plasma water Ca++ concentrations were statistically significantly higher with a dialysate tCa concentration of 1.50 mmol/L. Mean tCaMBs were positive (diffusion gradient from the dialysate to the patient), increasing with increasing dialysate tCa concentrations (+75 ± 122 mg, +182 ± 125 mg, +293 ± 228 mg, respectively). Their difference was statistically significant (p<0.0005). Mean Na+MBs and K+MBs were not statistically significantly different. SBP, DBP, MAP and HR were not statistically significantly different among the 3 treatments. These highly controlled experiments showed that hemodynamic stability does not appear to be statistically significantly influenced by any specific dialysate tCa concentration in this peculiar subset of patients.

Measuring Total Blood Calcium Displays a Low Sensitivity for the Diagnosis of Hypercalcemia in Incident Renal Transplant Recipients

Hypercalcemia is a common complication in renal transplant recipients and has been associated with nephrocalcinosis and poor graft outcome. The performance of total calcium (tCa) in the diagnosis of blood calcium disturbances in renal transplant recipients is unknown. We compared the ability of total tCa concentration to identify low, normal, or high ionized calcium (iCa) concentration, i.e., the gold standard, in an unselected cohort of 268 renal transplant recipients. All patients were studied 3 and 12 months after successful engraftment. Hypercalcemia, defined as a iCa >1.29 mmol/L, was present in 58.6 and 44.8% of the patients at months 3 and 12, respectively. tCa concentrations >10.3 mg/dl, conversely, were observed in only 13.1% of the patients. Measuring tCa had a low sensitivity (20.3 and 24.2% at months 3 and 12, respectively) for the diagnosis of hypercalcemia. The agreement (κ coefficient [95% confidence interval]) between tCa concentrations and iCa was poor (month 3: 0.11 [0.05 to 0.17]; month 12: 0.20 [0.11 to 0.30]). The risk for underestimating iCa was increased by a low total bicarbonate concentration. Metabolic acidosis was observed in 48.1 and 37.3% of the patients at months 3 and 12, respectively. Total calcium greatly underestimates the diagnosis of hypercalcemia in incident renal transplant recipients. This is mainly explained by the high prevalence of metabolic acidosis in these patients.

Comparative study of trichloroacetic acid versus glycolic acid chemical peels in the treatment of melasma

Melasma is a common cause of facial hyperpigmentation with significant cosmetic deformity. Many modalities of treatment are available, but none is satisfactory. This study was designed to compare the therapeutic response of melasma in Indian women to glycolic acid (GA 20-35%) versus trichloroacetic acid (TCA 10-20%) for chemical peeling. Forty nonpregnant female patients with a minimum melasma area and severity index (MASI) of 10 were recruited in the study. After a detailed history and clinical examination under natural light, MASI was calculated and color photographs were taken of all the patients. The patients were advised to carry out a prepeel program of daily application of 12% GA cream or 0.1% tretinoin at night for 2 weeks. They were then treated with graded concentrations of 20-35% GA facial peel every 15 days in GA group and 10-20% TCA in the second group. Objective response to treatment evaluated by reduction in MASI scoring after 12 weeks was by 79% reduction (from 26.6 to 5.6) in GA group and by 73% reduction in TCA group (from 29.1 to 8.2) but this difference was not significant. Patients with epidermal-type melasma showed a better response to treatment than those with mixed-type melasma (P<0.05). Subjective response, as graded by the patient, showed good or very good response in 75% in GA group and 65% in TCA group. No relation of treatment response to age and duration of melasma could be established in this study. A prepeel program of daily application of 12% GA cream at night for 2 weeks, followed by graded increase in GA and TCA concentrations proved to be an equally effective treatment modality for epidermal and mixed melasma. There are hardly any major side effects, and regular use of sunscreens prevents chances of postpeel hyperpigmentation. GA peel is associated with fewer side effects than TCA and has the added advantage of facial rejuvenation.

Purge and Trap Sampling Coupled to Curie Point Thermal Desorption for the Detection of Parts per Trillion 2,4,6-Trichloroanisole in Water

GC–MS analysis based on purge and trap sampling followed by Curie point thermal desorption was examined for the quantitative determination of 2,4,6-trichloroanisole in aqueous solutions. The method developed showed linearity in single ion monitoring mode over a TCA concentration range of 0.12–120 ng L−1 (parts-per-trillion).

A comparison of total calcium, corrected calcium, and ionized calcium concentrations as indicators of calcium homeostasis among hypoalbuminemic dogs requiring intensive care

(1) To evaluate whether total calcium (tCa) correlates with ionized calcium (iCa) in hypoalbuminemic dogs; (2) to evaluate whether calcium adjusted for albumin (Alb), or total protein (TP), or both accurately predict iCa concentrations and hence can be used to monitor calcium homeostasis in critically ill hypoalbuminemic dogs; and (3) to evaluate factors associated with any potential discrepancy in calcium classification between corrected total and ionized values. Prospective observational clinical study. Small animal intensive care unit in a veterinary medical teaching hospital. Twenty-eight client-owned dogs with hypoalbuminemia. None. iCa was determined using ion-specific electrode methodology, on heparinized plasma. The tCa concentration was adjusted for Alb and TP using published equations. In total 29% (8/28) of the hypoalbuminemic, critically ill dogs in this study were hypocalcemic at intensive care unit admission, as determined by iCa measurement. Corrected calcium values failed to accurately classify calcium status in 67.9% and 64.3% of cases, according to whether the Alb-adjusted or TP-adjusted values, respectively, were used. The sensitivity and specificity of the tCa to evaluate hypocalcemia was 100% and 47%, respectively. The sensitivity and specificity of the correction formulae were 37.5% and 79% for the Alb-adjusted values and 37.5% and 74% for TP-adjusted values. tCa overestimated the presence of hypocalcemia and underestimated the presence of normocalcemia, while corrected calcium values overestimated the presence of normocalcemia and underestimated the presence of hypocalcemia. Calcium homeostasis in hypoalbuminemic critically ill dogs should be evaluated by iCa concentrations rather than tCa or calcium adjusted for Alb or TP. Given that tCa has 100% sensitivity for detecting hypocalcemia in this population it is recommended that all hypoalbuminemic and critically ill patients with low tCa should be evaluated with an iCa measurement.

Production of hydrogen by Clostridium species in the presence of chlorinated solvents

Although anaerobic bioremediation of chlorinated organic contaminants in the environment often requires exogenous supply of hydrogen as an electron donor, little is known about the ability of hydrogen-producing bacteria to grow in the presence of chlorinated solvents. In this study, 18 Clostridium strains including nine uncharacterized isolates originating from chlorinated solvent contaminated groundwater were tested to determine their ability to fermentatively produce hydrogen in the presence of three common chlorinated aliphatic groundwater contaminants: 1,2-dichloroethane (DCA), 1,1,2-trichloroethane (TCA), and tetrachloroethene (PCE). All strains produced hydrogen in the presence of at least 7.4 mM DCA, 2.4 mM TCA, and 0.31 mM PCE. Some strains produced hydrogen in media containing concentrations as high as 29.7 mM DCA, 9.8 mM TCA, and 1.1 mM PCE. None of the strains biotransformed chlorinated solvents under the conditions tested. Results demonstrate that many Clostridium species are chlorinated solvent tolerant, producing hydrogen even in the presence of high concentrations of DCA, TCA, and PCE. These findings have important implications for bioremediation of contaminated soil and groundwater.

Electrochemical and Spectroscopic Behavior of Iron(III) Porphyrazines in Langmuir−Schäfer Films

Thin films of a newly synthesized iron(III) porphyrazine, LFeOESPz ( L = ClEtO, OESPz = ethylsulfanylporphyrazine), have been deposited by the Langmuir-Schafer (LS) technique (horizontal lifting) on ITO or gold substrates. Before deposition, the floating films have been investigated at the air-water interface by pressure/area per molecule (pi/ A) experiments, Brewster angle microscopy (BAM) and UV-vis reflection spectroscopy (RefSpec). The complex reacts with water subphase (pH 6.2) forming the mu-oxo dimer, which becomes the predominant component of the LS films ( LS-Fe) as indicated by optical, IR, XPS, and electrochemical data. LS-Fe multilayers exhibit, between open circuit potential (OCP) and +0.90 V (vs SCE), two independent peak pairs with formal potentials, E surf (I) and E surf(II) of +0.56 V and +0.78 V, respectively. According to dynamic voltammetric and coulometric experiments the peak pair at +0.56 V is attributed to one-electron process at the iron(III) centers on the monomer, while the peak pair at +0.78 V is associated to a four-electron process involving mu-oxo-dimer oligomers. LS-Fe films prove to be quite stable electrochemically between OCP and +0.90 V. The electrochemical stability decreases, however, when the potential range is extended both anodically and cathodically outside these limits, due to formation of new species. Upon incubation with TCA solutions, LS-Fe films show remarkable changes in the UV-vis spectra, which are consistent with a significant mu-oxo dimer --> monomer conversion. Addition of TCA to the electrochemical cell using a LS-Fe film as working electrode, results in a linear increase of a cathodic current peak near -0.40 V as the TCA concentration varies in the 0.1-2.0 mM range. This behavior is interpreted in terms of TCA inducing a progressive change in the composition of the LS-Fe films in favor of the monomeric iron(III) porphyrazine, which is responsible for the observed increase in the cathodic current near -0.40 V.

Pitfalls of Measuring Total Blood Calcium in Patients with CKD

Disorders of mineral and bone metabolism are prevalent in patients with chronic kidney disease (CKD). The recent National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend that blood calcium (Ca) be regularly measured in patients with stages 3 to 5 CKD. The Kidney Disease: Improving Global Outcomes (KDIGO) position states that the measurement of ionized Ca (iCa) is preferred and that if total Ca (tCa) concentration is used instead, then it should be adjusted in the setting of hypoalbuminemia. In 691 consecutive patients with stages 3 to 5 CKD, we compared the ability of noncorrected and albumin-corrected tCa concentration to identify low, normal, or high iCa concentration. The agreement between noncorrected or albumin-corrected tCa and iCa was only fair. The risk for underestimating ionized calcium was independently increased by a low total CO(2) concentration when either noncorrected or albumin-corrected Ca was used and by a low albumin concentration only when noncorrected tCa was used. The risk for overestimating iCa was increased by a low albumin concentration only when albumin-corrected Ca was used. In conclusion, albumin-corrected tCa does not predict iCa better than noncorrected tCa. Moreover, both noncorrected and albumin-corrected tCa concentrations poorly predict hypo- or hypercalcemia in patients with CKD.

Screening of musty-earthy compounds from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry

Compounds responsible for musty-earthy off-flavours in cork, namely 2-methylisoborneol (MIB), geosmin (GSM), 2,4,6-trichloroanisole (TCA) and 2-methoxy-3-isopropylpyrazine (IPMP), were determined from tainted cork using water-based soaks followed by headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME–GC–MS). The influence of the fibre coating used and of the extraction time and temperature were investigated for the joint analysis of MIB, GSM, TCA and IPMP. Considering the obtained results, an extraction time of 30 min at a temperature of 50 °C were fixed as experimental conditions, using a divinylbenzene/carboxen-polydimethylsiloxane/polydimethylsiloxane (DVB/CAR/PDMS) fibre. Quality parameters of the chromatographic method were obtained and good recoveries (117–128%) were found in spiked aqueous cork macerates. Using the same experimental conditions, the presence of guaiacol, 2,3,4,6-tetrachloroanisole (TeCA), pentachloroanisole (PCA), 2,4,6-tribromoanisole (TBA) and 2-methoxy-3,5-dimethylpyrazine (MDMP) could also be evaluated in a single chromatogram. From all the compounds analyzed in tainted samples, TCA and guaiacol were the only contaminants present and only TCA concentrations were found above its perception threshold in water.

Evaluation of total and ionized calcium status in dogs with blastomycosis: 38 cases (1997–2006)

To determine blood ionized calcium (iCa) and serum total calcium (tCa) concentrations in dogs with blastomycosis and to evaluate whether serum tCa concentration, albumin-adjusted serum calcium concentration (AdjCa-Alb), and total protein-adjusted serum calcium concentration (AdjCa-TP) accurately predict iCa status. Retrospective case series. 38 client-owned dogs with a cytologic diagnosis of blastomycosis. Dogs were classified as hypocalcemic, normocalcemic, or hypercalcemic on the basis of blood iCa concentration, serum tCa concentration, AdjCa-Alb, and AdjCa-TP; classification on the basis of serum tCa concentration, AdjCa-Alb, and AdjCa-TP was compared with blood iCa concentration. Except for 2 hypercalcemic dogs, all dogs had blood iCa concentrations within the reference interval. Use of serum tCa concentration overestimated hypocalcemia in 57.9% (22/38) of dogs and underestimated hypercalcemia in 1 dog. Use of AdjCa-Alb correctly reclassified all dogs as normocalcemic that were classified as hypocalcemic on the basis of serum tCa concentration, but failed to predict hypercalcemia in 1 dog. Use of AdjCa-TP correctly reclassified all but 2 dogs as normocalcemic that were classified as hypocalcemic on the basis of serum tCa concentration, and failed to predict hypercalcemia in 1 dog. No correlation was found between blood iCa concentration and serum concentrations of tCa, total protein, and albumin; AdjCa-Alb; or AdjCa-TP. High blood iCa concentration was uncommon in dogs with blastomycosis. Hypoalbuminemia contributed to a low serum tCa concentration despite a blood iCa concentration within reference limits. The use of serum tCa concentration, AdjCa-Alb, and AdjCa-TP may fail to identify a small number of dogs with high blood iCa concentrations.

Serum concentrations of calcium, phosphorus, magnesium and calciotropic hormones in donkeys

To provide reference values for serum biochemical variables that are used for evaluation of mineral metabolism in donkeys and compare values with those in horses. 18 donkeys and 18 horses. Total calcium (tCa), total magnesium (tMg), and inorganic phosphorus (P) concentrations were measured in serum samples via spectrophotometry. Ionized calcium (iCa) and magnesium (iMg) concentrations were quantified with selective electrodes. By use of a micropartition system, tCa and tMg were fractionated to separate protein-bound (pCa, pMg) and ultrafiltrable fractions. Complexed calcium (cCa) and magnesium (cMg) concentrations were calculated by substracting ionized fractions from ultrafiltrable fractions. Parathyroid hormone (PTH) and calcitriol (CTR) concentrations were measured via radioimmunoassay. Serum tCa concentration in donkeys (3.37 +/- 0.21 mmol/L) was composed of pCa (1.59 +/- 0.21 mmol/L [47.0 +/- 4.2%]), iCa (1.69 +/- 0.04 mmol/L [50.4 +/- 3.0%]), and cCa (0.09 +/- 0.08 mmol/L [2.6 +/- 2.9%]). Serum tMg concentration (1.00 +/- 0.08 mmol/L) was fractioned in pMg (0.23 +/- 0.08 mmol/L [23.4 +/- 8.1%]), iMg (0.59 +/- 0.04 mmol/L [58.8 +/- 5.1%]), and cMg (0.18 +/- 0.08 mmol/L [17.8 +/- 7.2%]). Serum concentrations of P (1.14 +/- 0.30 mmol/L), PTH (20.4 +/- 21.2 pg/mL), and CTR (13.4 +/- 5.9 pg/mL) were determined. Serum variables of mineral metabolism in donkeys were within reference ranges for horses. However, when compared with horses, donkeys had higher iCa, cMg, and CTR and lower pMg and PTH concentrations.