Exploratory evaluation of iron and its speciation in surface waters of Admiralty Bay, King George Island, Antarctica.

The determination of dissolved iron concentrations and speciation was conducted for the first time in surface seawater coastline samples collected during the austral summer of 2020 in Admiralty Bay, King George Island, Antarctica. The technique of competitive ligand exchange/adsorptive cathodic stripping voltammetry with 2,3-dihydroxynaphthalene as the competing ligand was evaluated, showing a sensitivity between 14.25 and 21.05 nA nmol L-1 min-1, with an LOD of 14 pmol L-1 and a mean blank contribution of 0.248 nmol L-1. Physicochemical parameters such as pH (7.85 ± 0.2), salinity (32.7 ± 0.8) and dissolved oxygen (51.3 ± 26.6%) were compatible with those of the literature; however, the average temperature (4.2 ± 0.8 °C) was higher, possibly as a reflection of global warming. The dissolved iron mean value was 18.9 ± 6.1 nmol L-1, with a total ligand concentration of 23.6 ± 12.2 nmol L-1 and a conditional stability complex constant of 12.2 ± 0.2, indicating humic substances as possible ligands. On average, the calculated free iron concentrations were 0.7 ± 0.3 pmol L-1. Relatively high concentrations of iron indicate a possible local source of Fe, likely predominantly from upwelling sediments and secondarily from ice-melting waters, which does not limit the growth of the phytoplankton.

Synovial Biomarkers to Detect Chronic Periprosthetic Joint Infection: A Pilot Study to Compare Calprotectin Rapid Test, Calprotectin ELISA Immunoassay and Leukocyte Esterase Test.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication after joint replacement surgery, and making diagnosis is often far from obvious. Calprotectin was recently proposed as a promising synovial biomarker to detect PJI. To our knowledge, no comparative study exists between enzyme-linked immunosorbent assay (ELISA) and rapid calprotectin test (CalFAST). Our purpose was to compare these methods with leukocyte esterase (LE) test from synovial fluid of painful knee arthroplasty subjected to infectious workup. METHODS: Ninety-three patients were included in this prospective observational study. They underwent synovial fluid aspiration that was analyzed for cell count, microbiological culture, LE test, calprotectin rapid test, and calprotectin immunoassay dosage. The 2018 Consensus Statements criteria for PJI were used to diagnose PJI. Sensitivity, specificity, positive and negative likelihood ratio, and receiver operating characteristic were calculated for detection methods and compared. RESULTS: We categorized 39 patients as infected and 50 patients as not infected. The sensitivity comparing the ELISA test and CalFAST test was similar, 92.3% and 97.4%, respectively. LE rapid test showed 46% of sensitivity and 94% of specificity. The highest specificity was found with ELISA test (100%). Comparing the receiver operating characteristic curves by z-test, there were statistically significant differences between LE strip test and the other two methods. Otherwise, no statistically significant differences were present between ELISA and CalFAST test. CONCLUSION: Synovial calprotectin detection has high accuracy in knee PJI diagnosis, both ELISA and rapid test. LE strip test remains a good test to confirm the diagnosis of PJI in case of positivity. In clinical practice, the calprotectin rapid test can be considered an excellent point-of-care test.

Alternative Ecosorbent for the Determination of Trihalomethanes in Aqueous Samples in SPME Mode.

A new sorbent material based on modified clay with ionic liquid immobilized into an agarose film was developed as part of this study. It was applied to determine organochlorine pollutants, like disinfection byproducts, through headspace solid-phase microextraction-gas chromatography-electron capture detection (HS-SPME-GC-ECD). The disinfection byproducts determined in this study were used as model molecules because they were volatile compounds, with proven severe effects on human health. Their presence in aquatic environments is in trace concentrations (from pg L-1 to mg L-1). They are classified as emergent pollutants and their determination is a challenge for analytical chemists. The parameters which affected the extraction efficiency, i.e., number and distance between SPME discs, salt concentration, the temperature of extraction, extraction time, and desorption time, were optimized. A wide linear dynamic range of 10-1000 ng mL-1 and coefficients of determination better than 0.997 were achieved. The limits of detection and the limits of quantitation were found in the ranges of (1.7-3.7) ng mL-1 and (5.6-9.9) ng mL-1, respectively. The precision, expressed as relative standard deviation (RSD), was better than 8%. The developed sorbent exhibits good adsorption affinity. The applicability of the proposed methodology for the analysis of trihalomethanes in environmental and water samples showed recoveries in the range of 86-95%. Finally, the newly created method fully complied with the principles of green chemistry. Due to the fact that the sorbent holder was made of agarose, which is a wholly biodegradable material, sorbent clay is a widespread material in nature. Moreover, the reagents intercalated into the montmorillonite are new green solvents, and during the whole procedure, low amounts of organic solvents were used.

Molecular and biochemical evaluation of effects of malathion, phenanthrene and cadmium on Chironomus sancticaroli (Diptera: Chironomidae) larvae.

In-vitro effects of sub-lethal concentrations of malathion, phenanthrene (Phe) and cadmium (Cd) were tested on Chironomus sancticaroli larvae in acute bioassays by measuring biochemical and molecular parameters. Malathion was evaluated at 0.001, 0.0564 and 0.1006 mg L-1; Phe at 0.0025, 1.25 and 2.44 mg L-1; and Cd at 0.001, 3.2 and 7.4 mg L-1. The recovery test carried out at the highest concentration of each compound showed that survival of larvae exposed to Phe ranged from 4% to 5%, while the effects of malathion and Cd were irreversible, not allowing the emergence of adults. Results showed that malathion and Cd inhibited AChE, EST-α and ES-ß activities at the two highest concentrations. Phe at 0.0025, 1.25 and 2.44 mg L-1; and Cd at 3.2 and 7.4 mg L-1 inhibited glutathione S-transferase activity. Oxidative stress was exclusively induced by the lowest concentration of malathion considering SOD activity once CAT was unaffected by the stressors. Lipid peroxidation was registered exclusively by malathion at the two highest concentrations, and total hemoglobin content was only reduced by Cd at the two highest concentrations. The relationship among biochemical results, examined using the PCA, evidenced that malathion and Cd concentrations were clustered into two groups, while Phe only formed one group. Four hemoglobin genes of C. sancticaroli were tested for the first time in this species, with Hemoglobin-C being upregulated by malathion. The toxicity ranking was malathion > Phe > Cd, while biochemical and molecular results showed the order malathion > Cd > Phe. Our results highlight the importance of combining different markers to understand the effects of the diverse compounds in aquatic organisms.

Mineral Content, Antioxidant Activity and Essential Oil of Allophylus edulis (A. St.-Hil., A. Juss. & Cambess.) Radlk. Leaves: Plant from South American Biodiversity.

Allophylus edulis (A. St.-Hil., A. Juss. & Cambess.) Radlk. (Sapindaceae) is an edible plant from the South American biodiversity that is a potential source of bioactive compounds. The mineral content and antioxidant activity of Allophylus edulis leaves were investigated, as well as the composition and the antioxidant activity of the essential oil. The mineral content was determined by ICP - OES and the antioxidant assays were assessed by ABTS, DPPH and FRAP. The essential oil was obtained by hydrodistillation and analyzed by GC/MS. Calcium, potassium, phosphorus, sulfur, and magnesium were the main minerals found in A. edulis leaves. Of the toxic metals that were present, a low level of aluminum was detected. The essential oil of A. edulis has (E)-nerolidol as major compound and both, the leaves, and the essential oil isolated from the leaves have antioxidant potential. These findings could provide a framework for developing new food and non-food products with A. edulis leaves.

In vitro Bioaccessibility of Proteins, Phenolics, Flavonoids and Antioxidant Activity of Amaranthus viridis.

The aim of this study was to investigate the chemical composition, mineral content and report the effect of gastrointestinal digestion on the proteins, phenolics, flavonoids and antioxidant activity of morphological parts of Amaranthus viridis (AV). The macronutrients found in the greatest quantity were proteins (leave, inflorescence and seeds) and fiber (roots and stem). The main minerals were calcium, potassium, iron and zinc. All the plant parts showed total phenolic (TPC) and total flavonoid (TFC) compounds that were correlated with antioxidant capacity (DPPH, ABTS and FRAP); the leaves and inflorescence presented the greatest potential. The antioxidant compounds from the leaves, inflorescence and roots decreased after static in vitro digestion, while the TPC and TFC of the digested seeds increased by more than 55%. Approximately 90% of the protein content was bioaccessible. To the best of our knowledge, for the first time, the bioaccessibility of proteins, phenolics, flavonoids and antioxidant activity of the leave, inflorescence, seeds, roots and stem from AV were reported. Taking into consideration the excellent nutritional properties, the morphological parts of the plant can be potentially explored as a source of protein, fiber, minerals and antioxidant compounds.

Synovial Fluid Calprotectin for the Preoperative Diagnosis of Chronic Periprosthetic Joint Infection.

BACKGROUND: The diagnosis of periprosthetic joint infection (PJI) represents a challenge in clinical practice and the analysis of synovial fluid is a useful diagnostic tool. Calprotectin is an inflammatory biomarker widely used in the evaluation of chronic inflammatory diseases; however, little is known about its role in PJI. The purpose of this study is to determine the reliability of synovial calprotectin in the diagnosis of PJI. METHODS: Seventy-six patients with painful knee arthroplasty were included in this prospective observational study. Synovial fluid was analyzed for cell count, percentage of polymorphonuclear neutrophils, microbiological culture, leukocyte esterase strip test, alpha-defensin rapid test, and calprotectin immunoassay dosage. The 2018 Consensus Statements criteria for PJI were used as standard reference to define the presence of infection. Sensitivity, specificity, positive and negative likelihood ratio, and receiver-operation characteristic curve were calculated for calprotectin immunoassay test. RESULTS: By 2018 Consensus Statements criteria for PJI, 28 patients were considered infected, 44 patients were considered not infected, and 4 patients were classified as inconclusive. The calprotectin synovial fluid test resulted in 2 false-positive results and no false-negative results. The calprotectin synovial fluid test demonstrated a sensitivity of 100% (95% confidence interval [CI] 99.96-100) and specificity of 95% (95% CI 89.4-100) for the diagnosis of PJI. The positive likelihood ratio was 22 (95% CI 5.680-85.209) and the negative likelihood ratio was 0 (95% CI 0-0.292). The area under the receiver-operation characteristic curve was 0.996 (95% CI 94.3-100). CONCLUSION: The present study suggests that synovial calprotectin immunoassay test has a high sensitivity and specificity in the diagnosis of knee PJI. Moreover, it is easily applied, quick and valuable in clinical practice.

Treatment of avascular osteonecrosis of femoral head by core decompression and platelet-rich plasma: a prospective not controlled study.

PURPOSE: Core decompression is a surgical option since the 1960s for hip osteonecrosis treatment. This technique promotes bone repair by reducing intramedullary pressure, but this is not often enough to stop the progression of necrosis. The aim of this study was to associate core decompression with the regenerative stimulus provided by platelet-rich plasma (PRP) and compare our results with other regenerative techniques. METHODS: Femoral head osteonecrosis was prospectively evaluated in 30 hips (22 patients, 15-60 years) treated by core decompression and PRP graft. Patients presented monolateral or bilateral osteonecrosis in stage I-IIA-IIB according to Arlet and Ficat classification. The outcome was assessed by changes in Harris Hip Score (HHS) and the need for total hip replacement (THA). RESULTS: The mean preoperative HHS was 64 points, at two years from surgery was roughly 84 points. Sixteen of 30 hips showed osteonecrosis progression of the femoral head and were converted to THA. At the five year follow-up, the survival rate was 100% for patients at stage I, 67% for stage IIA, and 0% for stage IIB and was 68% and 32% for idiopathic and secondary osteonecrosis, respectively. CONCLUSION: Core decompression combined with PRP could be indicated as a treatment for the I and IIA stages of osteonecrosis, as it significantly reduces joint pain and delays THA. This procedure should be avoided in AVNFH related to cortisone therapy because only a few benefits have been proven. It also has the advantage of being technically simple, minimally invasive, and free from complications.

Cation Exchange Reactions in Layered Double Hydroxides Intercalated with Sulfate and Alkaline Cations (A(H2O)6)[M2+6Al3(OH)18(SO4)2]·6H2O (M2+ = Mn, Mg, Zn; A+ = Li, Na, K).

Layered double hydroxides (LDHs) with similar compositions to the minerals shigaite, natroglaucocerinite, and motukoreaite were synthesized by co-precipitation with increasing pH and characterized by several instrumental techniques. These minerals have previously been described to occur only with sodium and sulfate (Na(H2O)6)[M+26Al3(OH)18(SO4)2]·6H2O (M2+ = Mn, Mg, and Zn). These phases were synthesized successfully along with others containing lithium and potassium. Cation exchange reactions were performed in the presence of alkaline metal sulfates, and for the first time several instrumental techniques were employed to show that the cations can be totally exchanged without removing the intercalated sulfate anions. This class of compounds, traditionally considered to be anion exchangers, can also be considered cation exchangers, which opens new avenues for future scientific and industrial applications.

Biological, biochemical and genotoxic effects of Sb in the midge Chironomus sancticaroli Strixino and Strixino, 1981 (Diptera: Chironomidae).

In aquatic systems, antimony (Sb) is found in the water column and associated with sediment particles being bioavailable to organisms. Consequently, toxic effects have been detected in benthic invertebrates, but the toxicity after Sb exposure in Chironomidae have not been investigated. Were investigated DNA damage, activities of cholinesterase (ChE), alpha and beta esterase (EST-α, EST-ß), glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) and lipid peroxidation after acute (48 h) and subchronic exposure (8 d). We also investigated the effects of subchronic (8 d) on development of larvae and chronic (25 d) Sb exposure on emergence and size of adults of Chironomus sancticaroli. Were analyze Sb nominal concentrations ranged from 0.5 to 800 µg.L-1. Genotoxic effects occurred at higher concentrations upon acute (50, 800 µg.L-1) and subchronic exposure (50 µg.L-1). Acute exposure increased ChE, EST-α, EST-ß, and GST activities. Subchronic Sb exposure increased EST-α activity at 0.2 µg.L-1 and GST activity at 5 µg.L-1. CAT activity increased at all concentrations while increasing lipid peroxidation levels were observed (1 µg.L-1, 5 µg.L-1 and 50 µg.L-1), indicating oxidative stress. All concentrations of Sb delayed larval development and decreased the number of emerging adults. At high concentrations (50, 500, 800 µg.L-1), the emerging adults were smaller. In conclusion, these varying genotoxic, biochemical and biological effects of Sb make a notable impact on the reproduction and population dynamics of C. sancticaroli.

Cytotoxicity and enzymatic biomarkers as early indicators of benthic responses to the soluble-fraction of diesel oil.

Xenobiotics from oil tanker leaks and industrial discharges are amongst the main human impacts to confined coastal areas. We assessed the genotoxic responses to the water-soluble fraction of diesel oil in the polychaete Laeonereis culveri and the bivalve Anomalocardia flexuosa, two widespread benthic species in subtropical estuaries from the Southwestern Atlantic. We hypothesized that the highest responsiveness would be expressed by significantly different biomarkers responses between control and oil-impacted treatments. Responsiveness to diesel oil was investigated using an experimental design with two fixed factors (contaminant percentages and times of exposure). After exposure, we monitored the responses of the oxidative stress enzymes and performed micronuclei tests. Results were congruent for both species. Antioxidant defense of glutathione S-transferase and the induction of micronuclei and nuclear buds, the latter just for the bivalve, were significantly affected by polycyclic aromatic hydrocarbons, with significant increases on the seventh day of exposure and in the higher concentrations, compared to controls groups. We assessed the benefits and drawbacks of using each biomarker in laboratory experiments. Both species are indicators of early, and rapid responses to genotoxic contaminants in subtropical estuarine habitats. We suggest that the micronuclei frequency in A. flexuosa is a simple, fast and cheap test for genotoxicity in oil-impacted areas. Such early biomarkers are needed to develop better protocols for impact assessment and monitoring under real field conditions.

Mechanochemical conversion of chrysotile/K2HPO4 mixtures into potential sustainable and environmentally friendly slow-release fertilizers.

Chrysotile fibers pose a threat to public health due to their association relation to respiratory malignant lung disease such as cancer. For this reason, they must be stored and discarded appropriately, including after treatment, which raises costs. In the present study, insoluble chrysotile fibers were milled in solid state with highly soluble K2HPO4, destroying both structures, making the chrysotile nontoxic and generating a new material with potential use as sustainable slow-release fertilizer (SSRF) containing mainly K and P. Based on the mills, milling conditions and chrysotile/K2HPO4 molar ratios used, Mg originating from chrysotile fibers reacted with K and P from dibasic potassium phosphate and were transformed into MgKPO4·H2O, MgKPO4·6H2O and probably a mixture of amorphous SiO2/MgO. In this study, a zirconia planetary mill and high-energy ball mill were used, both of them produced SSRF. In conclusion, it was possible to synthesize high-value and extremely useful materials for agriculture using a harmful waste. The release rate can be tailored by controlling chrysotile/K2HPO4 molar ratios, grinding speed and time, which makes the process even more promising for farming applications.

Determination of labile species of As(V), Ba, Cd, Co, Cr(III), Cu, Mn, Ni, Pb, Sr, V(V), and Zn in natural waters using diffusive gradients in thin-film (DGT) devices modified with montmorillonite.

A binding phase based on the clay mineral montmorillonite (MT) was used as a sorbent in this work, which employed diffusive gradients in thin-film (DGT) devices to determine the lability of trace elements in natural waters. Montmorillonite exhibits low cost, wide availability, ease of handling, high ion-exchange capacity, and reusability. As(V), Ba2+, Cd2+, Co2+, Cr(III), Cu2+, Mn2+, Ni2+, Pb2+, Sr2+, V(V), and Zn2+ were quantitatively sorbed by MT and eluted with 1.0 mol L-1 HNO3, which provided efficiency above 70% of recovery. Validation tests were performed with synthetic solutions. The recovery of known concentrations ranged from 83 to 110%. The performance of modified DGT was compared with conventional DGT devices in experiments lasting 6 and 48 h. The results obtained with both DGT devices showed no significant differences with 95% confidence. DGT samplers with MT were deployed in the determination of labile forms of the elements in water samples from Iguaçu River (Paraná, Brazil). The measured masses of elements in MT for various durations showed good fit to a theoretical line, indicating that the results agreed with the principle of the DGT technique. The concentrations of labile species in the sample proceeded as follows; Sr > Cd > Ba > Cu > Cr > Mn > Zn > Pb. The results suggest that DGT devices with MT are an effective alternative for speciation analysis of a wide range of elements (cations as well as anions) in natural waters.

Polybrominated diphenyl ethers (PBDEs) effects on Chironomus sancticaroli larvae after short-term exposure.

In-vivo effects of polybrominated diphenyl ethers (PBDEs) containing 3, 4 and 5 bromine atoms were tested on fourth-instar larvae of Chironomus sancticaroli (Diptera: Chironomidae) after 48h of exposure, by measuring the activity of the acetyl cholinesterase, alpha and beta esterases and glutathione S-transferase. The PBDE congeners 2,2',4-triBDE (BDE-17), 2,2',4,4'-tetraBDE (BDE-47) and 2,2',4,4',5-pentaBDE (BDE-99) were evaluated at 0.5, 1.0, 2.0 and 3.0ngmL-1. Acetyl cholinesterase activity decreased significantly (p≤0.05) at all evaluated concentrations of the three PBDE congeners, except for larvae exposed to BDE-17 at 1.0 and 2.0ngmL-1. The significant inhibition of acetyl cholinesterase activity ranged from 18% (BDE-47 at 0.5ngmL-1) to 72% (BDE-47 at 2.0ngmL-1). The enzymes alpha and beta esterase were also affected by the three congeners, reducing their activity from 14% (BDE-99 at 1.0ngmL-1) to 52% (BDE-47 at 2.0ngmL-1) and from 7% (BDE-99 at 2.0ngmL-1) to 34% (BDE-47 at 3.0ngmL-1) respectively. Substantial increments in glutathione S-transferase activity were similarly observed, varying from 138% (BDE-99 2.0 at ng mL-1) to 346% (BDE-17 at 1.0ngmL-1). DNA strand breaks were detected exclusively in larvae exposed to BDE-99 at 2.0 and 3.0ngmL-1 (H=11.7, p=0.019). These results showed that C. sancticaroli larvae were sensitive to the PBDEs treatments under the experimental conditions.

Determination of monoaromatic hydrocarbons (BTEX) in surface waters from a Brazilian subtropical hydrographic basin.

This study examined surface water samples for the presence of the monoaromatic hydrocarbons benzene, toluene, ethylbenzene and xylene. Water samples were collected from the sub-basin of the Tegas River and the Marrecas Stream microbasin located in the metropolitan region of the municipality of Caxias do Sul (Rio Grande do Sul State, Brazil). For all sampling points evaluated, only toluene was detected, with concentrations values in the range of 1.70-18.44 µg L(-1). In general, the relatively high toluene concentration for the samples collected were above the limit of 2 µg L(-1) established by the Brazilian government for Class I rivers for the protection of aquatic life. However, they were well below the established limit of 170 µg L(-1) in water used for human consumption.

Early Biofilm Formation on the Drain Tip after Total Knee Arthroplasty Is Not Associated with Prosthetic Joint Infection: A Pilot Prospective Case Series Study of a Single Center.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication of arthroplasties that could occur during the surgery. The purpose of this study was to analyze the biofilm formation through microbiological culture tests and scanning electron microscopy (SEM) on the tip of surgical drainage removed 24 h after arthroplasty surgery. METHODS: A total of 50 consecutive patients were included in the present prospective observational study. Drains were removed under total aseptic conditions twenty-four hours after surgery. The drain tip was cut in three equal parts of approximately 2-3 cm in length and sent for culture, culture after sonication, and SEM analysis. The degree of biofilm formation was determined using a SEM semi-quantitative scale. RESULTS: From the microbiological analysis, the cultures of four samples were positive. The semi-quantitative SEM analysis showed that no patient had grade 4 of biofilm formation. A total of 8 patients (16%) had grade 3, and 14 patients (28%) had grade 2. Grade 1, scattered cocci with immature biofilm, was contemplated in 16 patients (32%). Finally, 12 patients (24%) had grade 0 with a total absence of bacteria. During the follow-up (up to 36 months), no patient showed short- or long-term infectious complications. CONCLUSIONS: Most of the patients who underwent primary total knee arthroplasty (TKA) showed biofilm formation on the tip of surgical drain 24 h after surgery even though none showed a mature biofilm formation (grade 4). Furthermore, 8% of patients were characterized by a positivity of culture analysis. However, none of the patients included in the study showed signs of PJI up to 3 years of follow-up.

Three predictive scores compared in a retrospective multicenter study of nonunion tibial shaft fracture.

BACKGROUND: Delayed union, malunion, and nonunion are serious complications in the healing of fractures. Predicting the risk of nonunion before or after surgery is challenging. AIM: To compare the most prevalent predictive scores of nonunion used in clinical practice to determine the most accurate score for predicting nonunion. METHODS: We collected data from patients with tibial shaft fractures undergoing surgery from January 2016 to December 2020 in three different trauma hospitals. In this retrospective multicenter study, we considered only fractures treated with intramedullary nailing. We calculated the tibia FRACTure prediction healING days (FRACTING) score, Nonunion Risk Determination score, and Leeds-Genoa Nonunion Index (LEG-NUI) score at the time of definitive fixation. RESULTS: Of the 130 patients enrolled, 89 (68.4%) healed within 9 months and were classified as union. The remaining patients (n = 41, 31.5%) healed after more than 9 months or underwent other surgical procedures and were classified as nonunion. After calculation of the three scores, LEG-NUI and FRACTING were the most accurate at predicting healing. CONCLUSION: LEG-NUI and FRACTING showed the best performances by accurately predicting union and nonunion.

Evaluation of organo-vermiculites as sorbent phases for solid-phase extraction of ibuprofen from water.

The study of ibuprofen (IBU) preconcentration was carried out making use of a homemade column for solid-phase extraction (SPE), using vermiculite (VT) or organo-vermiculites (OVTs) as sorbent phases. Aqueous samples (50.0 mL) percolated the column and IBU was sorbed onto the VT or OVT and then desorbed using acetonitrile. Employing this SPE system and OVT, calibration curves were generated for IBU, by spectrophotometric quantification using the α-naphthylamine method. R2 values higher than 0.9950 and LOD between 12 and 18 µg L-1 were observed, for real enrichment factors of 21 and 31, by using OVTs. The analytical protocol was applied to three water samples, which were spiked with IBU solutions to evaluate the precision and accuracy of the method. Recoveries between 77 and 110% at three different IBU concentrations and RSD lower than 18% were observed, even by using the spectrophotometric method. The protocol developed in this study demonstrated that the OVT was appropriate to work as a preconcentration phase for IBU determination in water samples.