Application of deep eutectic solvent as a disperser in reversed-phase dispersive liquid-liquid microextraction for the extraction of Cd(II) and Zn(II) ions from oil samples

A new, sensitive, and safe pretreatment method for the analysis of Cd(II) and Zn(II) ions in oil samples prior to flame atomic absorption spectrometry was developed. For the first time, a deep eutectic solvent is used as a disperser in reversed-phase dispersive liquid-liquid microextraction procedure. For this purpose, a deep eutectic solvent with low viscosity and miscible with both aqueous and organic phases is prepared by mixing glycolic acid and mandelic acid at a molar ratio of 2:1. The variables involved in this process were studied to provide high enrichment factors. Under optimized conditions, the linear ranges of calibration curves for Cd(II) and Zn(II) ions were obtained 0.30−20 and 0.50−30 μg L⁻¹, respectively. The obtained detection limits and enrichment factors were 0.12 and 0.18 μg L⁻¹; and 32.7 and 32.2 for Cd(II) and Zn(II), respectively. Repeatability of the proposed method, expressed as relative standard deviation, ranged from 2.7 to 4.1 % (n = 6, C = 1 μg L⁻¹ of each cation). Finally, the proposed method was successfully applied for the determination of Cd(II) and Zn(II) concentrations in various oil samples.     

Fluorometric method based on molecular recognition solid-phase extraction for determination of riboflavin in milk and infant formula

Riboflavin (vitamin B₂) is involved in several biological processes, particularly in energy production, and it is acquired from food ingestion, principally from supplemented food during the first years of life. Therefore, a simple, fast and cost-effective high-throughput method for determination of riboflavin in milk and infant formula is proposed, based on selective extraction using commercially available molecularly imprinted polymers targeted to riboflavin, followed by direct fluorometric determination. Several aspects were studied, namely microplate assay conditions, the composition of eluting solution and the stability of riboflavin in the eluate. Hence, elution using 1% (v/v) acetic acid in methanol or in acetonitrile is recommended, followed by immediate analysis or solvent evaporation, with reconstitution and analysis within 24 h. The proposed method provided a LOD of 0.03 mg L⁻¹, with working range for undiluted samples between 0.125 and 2 mg L⁻¹, and sample throughput of 24 h⁻¹. It was successfully applied to certified reference material NIST-1846 and also to commercial milk and infant formula samples.     

Synthesis and characterization of functionalized silica with 3,6-ditia-1,8-octanediol for the preconcentration and determination of lead in milk employing multicommuted flow system coupled to FAAS

Novel functionalized silica, containing 3,6-dithia-1,8-octanediol (Si-DIO), was synthesized and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR) of ¹³C and ²⁹Si. The Si-DIO was used to pre-concentrate and determine the amount of Pb(II) in milk samples employing a multicommuted flow system coupled to flame atomic absorption spectrometry (FAAS). For the adsorption process, a pre-concentration minicolumn with 100 mg of Si-DIO, a solution of 0.005 mg L⁻¹ Pb(II) at pH 9.0 and HNO₃ as the eluent was used, obtaining an enrichment factor of 28 times with retention efficiency higher than 99%. The Pb(II) ion, using the multicommuted flow system coupled to FAAS, showed a linear response between 0.005 and 20.0 mg L⁻¹; a linear coefficient where r = 0.9939 and n = 7; a detection limit estimated at 0.001 mg L⁻¹ and a relative standard deviation of 3.8% (n = 50). Fifty pre-concentrations runs were tested in the minicolumn without significant variation in the analytical signal. The proposal system showed analytical applicability to determine Pb(II) ion in milk samples, presenting recovery of 90.7–102.5%.     

Spectrophotometric method for determination of aluminium content in water and beverage samples employing flow-batch sequential injection system

A sensitive, precise and reliable flow-batch method for the determination of aluminium (Al) was developed using a sequential injection-monosegmented flow system incorporating a mixing chamber unit. Eriochrome cyanine R (ECR) was used as a chromogenic reagent in the presence of N,N-dodecyltrimethylammonium bromide (DTAB). The Al-ECR complex at pH 6 gave a maximum absorption at 584 nm. In-line single standard calibration and a standard addition procedure were developed employing the monosegmented flow technique. Under the optimum conditions, a linear calibration graph in the range of 0.0075–0.625 mg L⁻¹ Al was obtained with limits of detection and quantitation of 0.0020 and 0.0070 mg L⁻¹, respectively. Relative standard deviations were 0.8 and 1.3% for 0.010 and 0.025 mg L⁻¹ Al (n = 11), respectively. A sample throughput of 24 h⁻¹ using an in-line standard calibration approach and 6 h⁻¹ using four standard addition levels was achieved. The developed system was successfully applied to water samples and beverage samples. The results agreed well with those obtained from the ICP-AES method. Good recoveries between 85 and 104% were obtained.     

Selective extraction of Cu+ and Cu2+ ions from mushroom and lichen samples prior to analysis by micro-volume UV-Vis spectrophotometry: Application of a novel poly (SMIm)-Tris-Fe3O4 nanocomposite

In this study, a novel poly (SMIm)-Tris-Fe₃O₄ nanocomposite was prepared for selective extraction of Cu⁺ and Cu²⁺ ions by ultrasound assisted-cloud point extraction (UA-CPE). The nanocomposite was characterized by analysis of ATR-FT-IR, ¹H NMR and XRD. After optimization of the extraction conditions, the copper ions were independently detected against sample blank at 347 nm by micro-volume UV–vis spectrophotometer. Under the optimal conditions, good linear relationship was obtained in the ranges of 0.3−150 and 10−350 μg L⁻¹ for each ion at pH 7.0 and pH 5.0, respectively, with a better regression coefficient than 0.992. The method detection limits, accuracy and precision were 0.095 and 3.03 μg L⁻¹, 91.5−96.0 % and 93.0−98.5 %, and 2.5–4.5 and 3.8–7.1 % (n:5, 25 and 100 μg L⁻¹) for Cu⁺ and Cu²⁺ ions, respectively. A preconcentration of 70-fold was obtained from 35-mL of sample. After validation, the method was successfully applied to determination of total Cu levels in lichen and mushroom samples after pre-reduction at pH 7.0, and the recoveries in the range of 90−96 % were obtained by two calibration approaches after spiking with 10 μg L⁻¹. The results were also statistically compared with those obtained by FAAS analysis to ensure accuracy and precision.     

Salting-out homogeneous liquid-liquid microextraction for the spectrophotometric determination of iodate in food grade salt

A simple and rapid method has been reported for the determination of iodate in food grade salt samples where iodate has been used for the oxidation of phenylhydrazine to phenyldiazonium ion which then couples with 2-naphthol or with 8-hydroxyquinoline to produce orange red azo dye. The dye was extracted with microliter volume of 2-propanol, when the phase separation occurred by addition of ammonium sulphate, a process called salting out homogeneous liquid liquid microextraction (SH-LLME), and analysed spectrophotometrically. Relative efficiencies of both the coupling reagents were compared for iodate determination, when both coupling agents, 8-hydroxyquinoline and 2-naphthol, produced relatively comparable results. The method has been optimized for the reaction time, and type of extracting solvent and salt for phase separation. A linear calibration curve was obtained for 0.08−10 mg L⁻¹ of iodate with correlation coefficient of 0.998 and limit of detection of 16 μg L⁻¹. Food grade salt samples have been analyzed with adequate recovery in spiking experiments, being, 86.2–114.6 (RSD, 6.6–12.6 %) and 90.8–111.3 (RSD, 7.1–12.6 %) using 2-naphthol and 8-hydroxyquinoline as a coupler, respectively. The SH-LLME avoids pH adjustment of the final test sample before extraction, and Cu(II) and Fe(III) up to 1 and 6 mg L⁻¹, respectively, can be tolerated. Enrichment factors with the two reagents in that order were 21 and 20, respectively.     

Effect of Cultivar and Harvest Date on Nitrate (NO3) and Nitrite (NO2) Content of Selected Vegetables Grown Under Open Field and Greenhouse Conditions in Jordan

Two cultivars each of spinach, lettuce, cabbage, squash, and cauliflowers, as well as one cultivar of parsley were grown in open fields. In addition, two cultivars each of squash, cucumber, and tomatoes were grown in polypropylene-covered greenhouses. The effects of cultivar and harvest date on the nitrate and nitrite content of the edible parts of these vegetables were studied. Harvest date was found to have a significant effect (P≤0.05) on the nitrate content of the open-field-grown spinach, cabbage, and squash, and the nitrite content of the open-field-grown spinach, lettuce, and cabbage. Late-harvested vegetables had the lowest nitrate levels, while the pattern of their nitrite content was irregular with respect to the dates that gave highest nitrite levels in each vegetable. Harvest date had no significant effect on either nitrate or nitrite content of the greenhouse-grown vegetables.Cultivar had a significant effect (P≤0.05) only on the nitrate content of the greenhouse-grown tomatoes and squash, while it had no effect on either the nitrate or the nitrite content of all other vegetables irrespective of their cultivation method, although their levels in the greenhouse-grown vegetables were higher than those grown in open fields. Nitrate levels in these vegetables were generally low (lowest average of 0.13 mg 100 g⁻¹in open-field-grown cauliflower, and highest of 4.77 mg 100 g⁻¹in greenhouse-grown squash). Nitrite levels, on the other hand, were similar to those reported elsewhere in the world, ranging from non-detectable levels in open-field-grown cauliflower, to a maximum level of 0.43 mg 100 g⁻¹in greenhouse-grown squash.A highly significant, although low, positive correlation (r=0.55, P≤0.01, n=108) was found between nitrate and nitrite contents of the greenhouse-grown vegetables, compared to a non-significant, and much lower correlation between the two variables in the open-field-grown vegetables.     

Zirconium nanoparticles based ligandless dispersive solid phase extraction for the determination of antimony in bergamot and mint tea samples by slotted quartz tube-flame atomic absorption spectrophotometry

A sensitive and effective analytical method was developed to preconcentrate antimony from the bergamot and mint tea samples for its determination at trace levels by slotted quartz tube-flame atomic absorption spectrophotometry (SQT-FAAS) system. The developed method was based on vortex assisted ligandless dispersive solid phase extraction (VA-LDSPE) using zirconium nanoparticles (Zr-NPs) as sorbent material for the adsorption of the target analyte. All variables involved in the DSPE method (pH value, nanoparticle amount, mixing and eluent type/volume) were optimized to boost the absorbance signal of antimony. Using the optimal parameters, the method provided satisfactory detection and quantification limits of 8.0 and 26.8 μg L⁻¹, respectively. A 180 folds enrichment factor was achieved by the developed method when compared with the detection power of the FAAS. Linear range of the proposed method was found to be 30–250 μg L⁻¹, with a coefficient of determination value of 0.9992. The established Zr-NPs-VA-LDSPE-SQT-FAAS method was successfully implemented to bergamot tea samples in order to check accuracy and applicability. The obtained recovery values ranged between 93–102%, and this demonstrated that the complex matrices tested did not affect the accuracy of quantifying antimony.     

An efficient,rapid and microwave-accelerated dispersive liquid–liquid microextraction method for extraction and pre-concentration of some organophosphorus pesticide residues from aqueous samples

In this paper, microwave-accelerated dispersive liquid–liquid microextraction has been developed for the extraction/preconcentration of some organophosphorus pesticides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, temperature of a high volume of aqueous sample is elevated by a microwave oven and then a mixture of extraction and disperser solvents is rapidly injected into the aqueous phase. After cooling to room temperature, the phase separation is accelerated by centrifuging. The main experimental factors affecting performance of the method including type and volume of the extraction and disperser solvents, temperature, pH, and salt addition were investigated and optimized. Under the optimum extraction conditions, the method resulted in low limits of detection and quantification within the ranges of 0.65–1.3 and 2.2–4.5 μg L⁻¹, respectively. Relative standard deviations were in the range of 2–7% (C = 40 or 100 μg L⁻¹) for intra-day (n = 6) and inter-day (n = 4) precisions. Finally, the proposed method was successfully applied to analysis of the target analytes in surface water and well water and fruit juice samples; diazinon was determined at μg L⁻¹ level in apple juice.     

Assessment of hydroxymethylfurfural and furfural in commercial bakery products

A survey was conducted on the presence of hydroxymethylfurfural (HMF) and furfural in bread and bakery products; for this purpose a reliable extraction procedure followed by high performance liquid chromatography (HPLC) was applied. The performance of the method was evaluated in terms of linearity (r always > 0.99); detection limits (0.001 mg L⁻¹ for furfural and 0.006 mg L⁻¹ for HMF); recovery percentages (98.5–100.5% for HMF and 94.9–98.9% for furfural); intraday precision (<4.65%) and interday precision (<7.51%). Two batches of a wide variety of products commercially available were analysed (a total of 88 samples). HMF and furfural levels presented high variability between products and batches of the same product. Cake/pastry samples showed the lowest HMF content (3.0 mg kg⁻¹ fw) while biscuits showed the highest content (7.8 mg kg⁻¹ fw) (p < 0.05). Regarding furfural, bread samples presented the highest furfural content (5.3 mg kg⁻¹ fw) (p < 0.05), cake/pastry and biscuits showed the lowest content (1.9 and 3.0 mg kg⁻¹ fw, respectively). Chocolate containing samples presented higher amounts of furfural (>20 mg kg⁻¹). These results indicate that special attention should be given to furfural content of bread (due to its daily high consumption) and re-evaluation of dietary exposure.     

Exposure to nickel through commercial premade baby foods: Is there any risk?

A study was performed to evaluate the risk regarding the presence of nickel in commercial premade baby foods: 26 ready meals, 31 fruits, 8 deserts and 20 paps. The analytical methodology used for the determination of nickel was dry ashing followed by graphite furnace atomic absorption spectrometry. Method detection limit (12.5 μg kg⁻¹) was obtained through a matrix matched calibration curve, using a nickel free commercial ready meal (meat).The results showed that 78 (91.8 %) samples contained nickel, with values up to 225.7 μg kg⁻¹. The group with the highest average concentration was the fruits (50.1 μg kg⁻¹) followed by the ready meals (40.2 μg kg⁻¹). Samples from organic farming presented higher detection frequency and average concentration (54.7 μg kg⁻¹) than the others. Using the average results, the tolerable daily intake proposed by EFSA (2.8 μg kg⁻¹ b.w.) was surpassed for the 2 year old age group, with daily ingestions up to 3.1 μg kg⁻¹ b.w.. This results highlight the risk promoted by the nickel present in commercial premade baby food.     

Variability of biogenic amine and free amino acid concentrations in regionally produced goat milk cheeses

The free amino acid composition and biogenic amine content were analysed in pasteurised goat milk cheeses produced in different regions in Spain. These goat cheeses are made with pasteurised milk to which a mesophilic starter culture is added; they are enzymatically coagulated, uncooked, pressed cheeses. They have a firm texture with a slight but typical goat milk aroma and flavour. The total free amino acids varied markedly among the samples, ranging from 1400 to 28,000 mg kg⁻¹ DM (dry matter). Of the 20 amino acids analysed, the most abundant were leucine, proline, valine, glutamic acid, lysine, glutamine, ornithine and γ-aminobutyric acid, which accounted for over 60% of the total free amino acids. The goat milk cheeses presented low concentrations of biogenic amines, the most abundant being tyramine and/or histamine, with values ranging from 4.2 to 50.7 and from 10.2 to 60.5 mg kg⁻¹ DM, respectively. Total biogenic amine content ranged between 26.4 mg kg⁻¹ DM and 175.1 mg kg⁻¹ DM, and was always below the level that is considered dangerous for humans. Therefore, taking into consideration the concentrations of BAs, these goat milk cheeses, produced under good hygienic conditions, can be considered safe for consumers.     

A rapid and sensitive method for the determination of dibutyl phthalate in wine by flow-injection chemiluminescence analysis

A sensitive method for the determination of picogram level dibutyl phthalate (DBP) in wine by flow-injection chemiluminescence (FI–CL) analysis is presented for the first time, which was based on the quenching effect of DBP on the luminol–myoglobin (Mb) CL system. The decrement of CL intensity was linearly proportional to the logarithm of DBP concentration in the range of 0.1–100 pg mL⁻¹ with the detection limit of 0.03 pg mL⁻¹ (3σ). At a flow rate of 2.0 mL min⁻¹, a complete determination of DBP including sampling and washing could be accomplished in 0.5 min, giving the maximum sample throughput of 120 h⁻¹. The proposed method was successfully applied to the determination of DBP in wine, human serum and urine samples with the relative standard deviations (RSDs) of less than 3.0% (n = 5). The molecule docking results showed that DBP interacted with the amino acid residues near the heme moiety of Mb. The possible CL mechanism of luminol–Mb–DBP reaction should be that the binding of Mb with DBP forming a 1:1 complex (binding constant K = 1.55 × 10⁴ L mol⁻¹) led to the conformational change of Mb and resulted in the quenching of CL intensity.     

A magnetic ion-imprinted polymer for lead(II) determination: A study on the adsorption of lead(II) by beverages

In this work a variety of beverage samples had been kept in a contaminated area to investigate their lead adsorption. To determine the adsorbed Pb(II), a novel magnetic lead ion-imprinted polymer, grafted onto Fe₃O₄ nanoparticles, was synthesized and used as a selective sorbent for the preconcentration of Pb(II) ions. The sorbent was characterized by different techniques. The synthesized sorbent was applied for highly accurate and selective determination of Pb(II) ions absorbed from polluted air in several beverages and results were compared. To validate the method, three certified reference materials were analyzed by the proposed method and the results showed that pre-concentrating by this sorbent and subsequent determination by flame atomic absorption spectroscopy is an accurate method for lead determination in beverage samples (recoveries higher than 95%). The limits of detection and the relative standard deviations were less than 1.7 μg kg⁻¹ and 4.1%, respectively. The sorption capacity of this new sorbent was 51.8 mg g⁻¹. Finally, this method was used for the determination of Pb(II) ions in polluted beverage samples, and the results revealed that under equal conditions, coffee exhibits more tendency to adsorb Pb(II) ions.     

Element analysis of dried figs (Ficus carica L.) from the Mediterranean areas

The minerals content of 36 dried figs samples collected from three Mediterranean areas in 2018 was presented in this study. The aim of this research was to evaluate whether the mineral elements amounts were significantly different among the production regions. Samples grown in Italy, Greece and Turkey were analyzed in this study. Samples were found to be a good source of potassium (average content between 3.5 ± 0.2 g kg⁻¹ and 8.12 ± 0.88 g kg⁻¹), calcium (between 1.46 ± 0.24 g kg⁻¹ and 4.49 ± 0.28 g kg⁻¹), magnesium (between 0.84 ± 0.04 g kg⁻¹ and 1.28 ± 0.15 g kg⁻¹), and sodium (between 0.45 ± 0.04 g kg⁻¹ and 0.70 ± 0.11 g kg⁻¹). Cadmium ad lead concentrations were always below the regulated values and below the quantification limit in all Italian samples, whereas chromium was detected in all samples from Greece (0.05 ± 0.01 mg kg⁻¹) and Turkey (0.03 ± 0.01 mg kg⁻¹), and in 65 % of samples from Italy (0.08 ± 0.02 mg kg⁻¹). Results confirm the good figs quality related to their essential trace elements content and they highlight the safety of these food products correlated to the intake of toxic elements. Furthermore, statistical analysis of the results pointed out that the mineral elements amount is significantly different among the three sample groups, hence it is possible to discriminate figs according to their geographical origin by PCA.     

Development of a new method for determination of aluminum (Al) in Jordanian foods and drinks: Solid phase extraction and adsorption of Al3+-d-mannitol on carbon nanotubes

In this work, a new method was developed for determination of aluminum (Al) in traditional Jordanian foods (Mansaf, Kofta, Tabboola, Hummous, bread), tea, Arabian coffee and water samples. The method involved solid phase extraction (SPE) of Al³⁺ from the digested samples after complexation with d-mannitol using carbon nanotubes (CNT) as the extractive sorbent. Formation of the Al³⁺-d-mannitol complex was confirmed by infrared spectroscopy. Optimization of the SPE method involved sample pH, d-mannitol-to-Al mole ratio, sample loading and elution flow rates, adsorbent mass, eluent concentration and volume. Based on spiked water samples, the characteristics of the method were as follows: the limit of quantification: 23 μg l⁻¹; sensitivity: 0.0036 (mg l⁻¹)⁻¹; %RSD range: 0.4–1.9%; recovery range: 76.0–93.0%. The equilibrium, thermodynamic and kinetic adsorption studies of Al³⁺-d-mannitol on CNT revealed that adsorption was spontaneous, exothermic, preferred, of physical nature; followed second-order rate kinetics; pore diffusion was not the only rate-controlling step; both Langmuir and Freundlich isotherms represented the data satisfactorily.     

A fast and effective method of quantitative analysis of VB1, VB2 and VB6 in B-vitamins complex tablets based on three-dimensional fluorescence spectra

Scattering signals and partial overlapping of target peaks usually appear in fluorescence determination. In this study, the improved wavelet moment method was proposed and applied to the quantitative determination of multiple target components in real B-vitamins complex tablets based on three-dimensional (3D) fluorescence spectra. The correlation coefficients (R) were more than 0.9939, and the correlation coefficients of leave-one-out cross-validation (R_LOO-cv) were more than 0.9376. The inter-day and intra-day variations were less than 5.8% and 6.1%, respectively. The recovery ranged from 97.6% to 109.4%. The limits of detection (LODs) and quantification (LOQs) were less than 0.07 μg mL⁻¹ and 0.13 μg mL⁻¹, respectively. All the statistical parameters indicated that the method was stable and reliable. The application to the practical samples confirmed that wavelet moment method effectively extracted the features of target components in 3D spectra and the proposed method could be applied to the analyses of food or other complex samples.     

Determination and chemometric evaluation of the mineral profile of maize flours

Maize flour is a food rich in nutrients important for the proper functioning of the human body. Nevertheless, for the determination of metals in maize flour there are few studies, which raise concern about quality and its mineral composition for consumption. In this work, it was evaluated the concentration of essential (Ca, Cu, Fe, Mn, Mg, Cr and Zn) and non-essential (Cd and Cr) metals in yellow and white maize flour samples produced in Paraná State - Brazil. For this purpose, it was performed a sample treatment employing wet digestion in a digester block and determination of metals by atomic absorption spectrometry (AAS). The highest concentrations found in the flour were Ca (55.4 mg kg⁻¹) and Mg (86.9 mg kg⁻¹) and the lowest concentrations were Cr (0.11 mg kg⁻¹) and Cd (0.01 mg kg⁻¹). In yellow and white maize flour the highest concentration was for Mg, 81.5 mg kg⁻¹and 98.4 mg kg⁻¹, respectively. Principal component analysis (PCA) showed that some samples had a similar mineral profile, such as the relationship with the place of origin of the cereal.     

Comparison of the chemical composition of British and Continental European bottled waters by multivariate analysis

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30 μg L⁻¹) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455 μg L⁻¹). Italian waters showed the highest concentrations of Sr (3000–8000 μg L⁻¹) and U (8–13 μg L⁻¹), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4 μg L⁻¹). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.     

Reduced water intake deteriorates glucose regulation in patients with type 2 diabetes

Epidemiological research has demonstrated that low daily total water intake is associated with increased diagnosis of hyperglycemia. Possible mechanisms for this increase include hormones related to the hypothalamic pituitary axis as well as the renin-angiotensin-aldosterone system (RAAS). Therefore, the hypothesis of the present study was that acute low water intake would result in differential hormonal profiles and thus impaired blood glucose regulation during an oral glucose tolerance test (OGTT) in people with type 2 diabetes mellitus (T2DM). Nine men (53 ± 9 years, 30.0 ± 4.3 m∙kg⁻², 32% ± 6% body fat) diagnosed with T2DM completed OGTTs in euhydrated (EUH) and hypohydrated (HYP) states in counterbalanced order. Water restriction led to hypohydration of −1.6% of body weight, with elevated plasma (EUH: 288 ± 4, HYP: 298 ± 6 mOsm·kg⁻¹; P < .05) and urine (EUH: 512 ± 185, HYP: 994 ± 415 mOsm·kg⁻¹; P < .05) osmolality. There was a significant main effect of condition for serum glucose (at time 0 minute 9.5 ± 4.2 vs 10.4 ± 4.4 mmol∙L⁻¹ and at time 120 minutes 19.1 ± 4.8 vs 21.0 ± 4.1 mmol∙L⁻¹ for EUH and HYP, respectively; P < .001) but not insulin (mean difference between EUH and HYP −12.1 ± 44.9 pmol∙L⁻¹, P = .390). An interaction between time and condition was observed for cortisol: decrease from minute 0 to 120 in EUH (−85.3 ± 82.1 nmol∙L⁻¹) vs HYP (−25.0 ± 43.0 nmol∙L⁻¹; P = .017). No differences between conditions were found within RAAS-related hormones. Therefore, we can conclude that 3 days of low total water intake in people with T2DM acutely impairs blood glucose response during an OGTT via cortisol but not RAAS-mediated glucose regulation.