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Hydrogen sulfite

Hydrogen sulfite, also known as bisulfite, is a chemical compound with the formula HSO3−.
It is an important industrial and laboratory reagent, with applications in food preservation, water treatment, and pharmaceuticals.
Hydrogen sulfite acts as a reducing agent, antioxidant, and preservative, making it useful in a variety of contexts.
Researchers studying hydrogen sulfite will find that PubCompare.ai can optimize their work by helping them identify the most accurate and reproducible protocols from the literature, pre-prints, and patents.
The AI-powered platform enables data-driven comparisons to pinpoint the best methodologies and products for their studies, enhancing the effeciency and quality of their hydrogen sulfite research.

Most cited protocols related to «Hydrogen sulfite»

Nutrient Digestibility Assessment in Horses

Cited 11 times

Nutrient digestibility was assessed through the use of internal (acid detergent insoluble ash, ADIA) and external (Titanium IV Dioxide, rutile; Sigma–Aldrich) markers. On d 27, baseline fecal samples were collected. From d 28 to 41, 5 g of titanium dioxide (TiO₂) was mixed into each concentrate meal. After a 10-d supplementation period, feces were collected from d 38 to 41 of the study. To account for diurnal variation of marker concentration, feces were collected twice daily at 12-h intervals, advancing by 3 h each subsequent day, which resulted in 8 fecal samples per mare over a 4-d collection period. After each collection time point, a 200 to 400 g sample of feces was stored at −20 °C before analysis.
To prepare samples for analysis, feces, hay, and grain were dried in a forced air oven at 55 °C for 96 h and allowed to equilibrate to room temperature for 24 h. All samples were weighed before and after the drying process to determine partial dry matter (DM) percentage. Samples were ground in a Wiley mill through a 1 mm screen. To determine overall DM percentage, samples were exposed to a 105 °C drying oven for 24 h. Similarly, to determine organic matter (OM) percentage, difference in sample weight was measured before and after exposure to a combustion oven at 450 °C for 8 h. The NDF and ADF values were determined by the Ankom Fiber Analyzer with sodium sulfite and α-amylase admitted and without correction for residual ash (Ankom Technology Corp., Macedon, NY). A Parr 6300 Calorimeter (Parr Instrument Company, Moline, IL) was used to measure gross heat energy (GE) for hay, grain, and fecal samples.
Forage consumption was estimated by TiO₂ analysis following a previously established protocol (Myers et al., 2004 (link)). Concentrate, hay, and fecal samples were ashed at 450 °C for 12 h then exposed to concentrated sulfuric acid (95% to 98% w/w) for 2 h before the addition of 30% hydrogen peroxide solution. Samples were digested at 350 °C for 45 min in a SCP digester. Absorbance at 410 nm was measured and compared with standards of 10, 8, 6, 4, or 2 mg TiO₂ per 50 g solution. The following calculations were used to estimate voluntary DMI of nutrients in the diet: mg TiO₂ / g = (mg TiO_{2 sample} / g sample) − (mg TiO_{2 baseline} / g sample); fecal output (kg/d) = (10 g/d TiO₂) / ([TiO₂] feces (g/kg), where [TiO₂] indicates concentration of TiO₂ in the feces; and DMI (kg/d) = fecal output (kg/d) × ([ADIA] feces/[ADIA] feed), where [ADIA] indicates concentration of ADIA.

Much M.L., Leatherwood J.L., Zoller J.L., Bradbery A.N., Martinez R.E., Keegan A.D., Lamprecht E.D, & Wickersham T.A. (2019). Influence of diet fortification on body composition and apparent digestion in mature horses consuming a low-quality forage. Translational Animal Science, 4(1), 1-9.

Publication 2019

Acids Amylase Cereals Circadian Rhythms Detergents Diet Feces Fibrosis Nutrients Peroxide, Hydrogen rutile sodium sulfite Suby's G solution Sulfuric Acids titanium dioxide

Evaluating Plant Defenses Against Insect Pests

Cited 4 times

To analyze plant defensive enzyme activities and concentrations of malondialdehyde (MDA) and soluble protein in response to LF infestation and Si amendment, the +Si and -Si 40-DAT potted rice plants were each divided into two groups: one was exposed to LF third instars and another, not exposed. Thus the plants were in four treatments: (1) without Si addition and LF infestation (-Si-LF); (2) without Si addition and with LF infestation (-Si+LF); (3) with Si addition and without LF infestation (+Si-LF); (4) with Si addition and LF infestation (+Si+LF). For the LF exposure treatments, one third-instar larva starved for 2 h was transferred with a pointed fine camel hair brush to the reciprocal fourth leaf of a randomly selected tiller. Ten tillers per pot were infested with LF larvae. The potted plants, whether exposed to LF infestation or not, were each caged with 60 mesh gauze. At 24, 48, 72, and 96 h after LF infestation, the reciprocal fourth leaves were harvested from LF-infested or un-infested plants and immediately maintained in liquid nitrogen for later analysis. The following measurements were each repeated three times using different leaf samples.
To determine the CAT, POD and SOD activities, frozen leaf samples of a treatment (0.5 g) were homogenized with a mortar and pestle in an ice bath with 100 mM phosphate buffer saline (PBS, pH 7.4), containing 1 mM EDTA and 1% (w/v) polyvinylpyrolidone (PVP), at a 1:10 ratio (fresh weight of leaf sample/buffer volume). The crude homogenates were centrifuged at 12,000 rpm for 15 min at 4°C (Centrifuge 5417R, Eppendorf, Hamburg, Germany). The supernatant was used to determine the enzyme activities using diagnostic kits (Nanjing Jiancheng Biotechnology Institute, China). CAT activity was measured according to the ammonium molybdate spectrophotometric method, based on the fact that ammonium molybdate could rapidly terminate the H₂O₂ degradation reaction catalysed by CAT and react with the residual H₂O₂ to generate a yellow complex, which could be monitored by the absorbance at 405 nm [28 ]. One unit of CAT activity was defined as the amount that reduces the level of H₂O₂ by 1 μmol per second per mg protein. POD activity was measured by a spectrophotometer (UNICO, UV-2000, Shanghai, China) following the change of absorption at 420 nm due to guaiacol oxidation [29 (link)]. One unit of POD activity was defined as the amount that catalyzes 1 μg substrate per minute per mg protein. For determination of SOD activity, 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2, 4-disulfophenyl)-2H-tetrazolium (WST -1) method was used [30 (link)]. WST-1 can couple with xanthine oxidase (XO) to generate superoxide anions (O₂^–) and formazan dye, which can be inhibited by SOD by catalysing O₂^– into H₂O₂ and O₂ [31 (link)]. Therefore, the SOD activity can be calculated by measuring the absorbance of formazan dye at 450 nm. One unit of SOD activity was defined as the amount that causes a 50% reduction in the absorbance at 450 nm by using a Multiskan Spectrum (Thermo Fisher Scientific Ltd., Finland).
Phenylalanine ammonia-lyase (PAL) activity was assayed according to the methods of Cai et al. [32 ], with minor modification. Leaf samples of a treatment (0.5 g) were homogenized with a mortar and pestle in an ice bath in 5 ml of 50 mM borate buffer (pH 8.8) containing 5.0 mM thioalcohol and 1 mM EDTA. The homogenate was centrifuged at 13,000 rpm for 10 min at 4°C. A reaction mixture containing 2 ml 50 mM borate buffer (pH 8.8) and 1.0 ml 20 mM L-phenylalanine was added to 0.2 mL of the crude homogenate. After incubation for 30 min at 40°C, the reaction was stopped by adding 0.25 ml of 5 M HCl. The increase in the absorbance at 290 nm due to the formation of trans-cinnamate was measured using the spectrophotometer. One unit of PAL activity was defined as the absorbance increase by 0.01 unit h⁻¹.
Polyphenol oxidase (PPO) was extracted following the method of Cai et al. [32 ]. Leaf samples of a treatment (0.25 g) were homogenized in an ice bath in 5 ml of 50 mM borate buffer (pH 8.7) containing 5.0 mM sodium hydrogen sulfite and 0.1 g PVP. The homogenate was centrifuged at 13,000 rpm for 10 min at 4°C. PPO activity was determined by adding 0.1 ml of the centrifuge supernatant to 3 ml of a solution containing 50 mM potassium phosphate buffer (pH 6.5) and 0.5 ml of 0.15 mM catechol. The increase of absorbance was measured at 420 nm by using the spectrophotometer for 10 min at 30°C [33 (link)]. One PPO unit was expressed as the variation of absorbance at 420 nm of soluble protein per minute.
The MDA content was determined by the thiobarbituric acid method using a commercial MDA assay kit (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) following the manufacturer’s protocols. This method is based on the reaction of MDA with thiobarbituric acid, forming stable thiobarbituric acid-reactive substances, which shows peak absorbance at 532 nm [34 (link)]. MDA concentration was recorded using the Multiskan Spectrum. The result was expressed as nmol/mg protein.
Concentration of soluble protein was determined by the Coomassie Blue method [35 (link)] using bovine serum albumin as a standard, and the absorbance of the samples was measured at 595 nm by using the Multiskan Spectrum.

Han Y., Li P., Gong S., Yang L., Wen L, & Hou M. (2016). Defense Responses in Rice Induced by Silicon Amendment against Infestation by the Leaf Folder Cnaphalocrocis medinalis. PLoS ONE, 11(4), e0153918.

Publication 2016

Comprehensive Corn Silage Nutrient Analysis

Cited 4 times

Sixty-four dairy farms located in the Po Valley (Italy) and Sardinia were randomly selected and visited in the 2017–2019 harvest seasons to collect corn silage samples. Corn silages were sampled at least 10 weeks after ensiling from horizontal bunker silos in agreement with the sampling procedure already described by Gallo et al. [40 (link)]. Samples of about 1.5–2 kg on a wet weight basis were sampled from at least 4 points of each silage feed-out face and analyzed as describe below.
All collected samples were split into 2 sub-samples of about 750–1000 g/sample of fresh matter. A sub-sample was treated as previously described by Gallo et al. [69 (link)] for chemical, biological, and mycotoxin analysis or by Gallo et al. [40 (link)] for characterizing fermentative traits. Briefly, samples were dried at 60 °C in a ventilated oven for 48 h until constant weight, then milled through a 1-mm screen using a laboratory mill (Thomas-Wiley, Arthur H. Thomas Co., Philadelphia, PA, USA) and stored until analysis.
All corn silages were analyzed for the presence and concentrations of fungal metabolites by LC–MS/MS at the Department of Agrobiotechnology according to Sulyok et al. [106 (link)]. As recently described by these authors, the analytical method has been extended to cover more than 500 metabolites. Briefly, 5 g of sample was weighed and extracted with 20 mL acetonitrile/water/acetic acid (79:20:1, v/v/v) for 90 min on a rotary shaker (GFL, Burgwedel, Germany). Extracts were diluted in extraction solvent (ratio 1:1) and directly injected into the LC–MS/MS instrument. All chromatographic characteristics were previously described [106 (link)]. Mycotoxins were quantified by external calibration (1/x weighted) using a multi-component standard prepared from authentic standards.
The DM was determined by gravimetric loss of free water by heating at 105 °C for 3 h (Association of Official Analytical Chemists or AOAC 1995, method 945.15); ash was determined as gravimetric residue after incineration at 550 °C for 2 h (AOAC 1995, method 942.05) and ether extract (EE) was obtained following the method 920.29 of AOAC (1995). The crude protein (CP, N × 6.25) was determined using the Kjeldahl method (AOAC 1995, method 984.13). The soluble fraction of CP (expressed on a DM basis) was determined according to Licitra et al. [107 (link)]. The neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin (ADL) were determined using the AnkomII Fiber Analyzer (Ankom Technology Corporation, Fairport, NY, USA) according to the method described by Van Soest et al. [108 (link)]. The NDF analyzes utilized a neutral detergent solution containing sodium sulfite and a heat-stable amylase (activity of 17.400 Liquefon units/ml, Ankom Technology). The NDF, ADF and ADL contents were corrected for the residual ash content. Starch was measured by polarimetry (Polax 2L, Atago^®, Tokyo, Japan). The disappearance of NDF after 24 h of rumen incubation (24 h NDFD) was measured in situ by incubating nylon bags in the rumen of two cannulated dry cows for 24 h [109 (link)]. Cows were daily fed about 10 kg DM of a total mixed ration consisting of alfalfa hay, ryegrass hay, corn silage and concentrate (i.e., 250, 350, 300, and 100 g/kg DM, respectively) in two portions at 8:00 a.m. and 6:00 p.m. The diet contained 120 g CP/kg DM and 550 g NDF/kg DM.
Immediately after collection, the second sub-sample was stored as wet at 4 °C and analyzed within 24 h for acetic acid, propionic acid, butyric acid, lactic acid, NH3-N, and pH. In particular, about 50 g of wet samples were extracted using a Stomacher blender (Seward Ltd., West Sussex, UK) for 3 min in distilled water at a water-to-sample (fresh weight) ratio of 3:1. The water mixture was then filtered through a gauze and an aliquot (10 mL approximately) of the resulting solution was centrifuged at 4500× g for 15 min. The liquid supernatant was micro-filtered on a 0.45 µm syringe filter and an aliquot of micro-filtered supernatant (1.5 mL) was transferred in a vial and added with 10 µL of internal standard solution (pivalic acid at 1.5% in distilled water) for VFA gas-chromatographic analysis [76 (link)]. The analysis was carried out using a 2025 GC with Flame Ionization Detector (FID) system (Shimadzu S.r.l., Milano, Italy) equipped with auto-sampler (AOC-20i Shimadzu S.r.l., Milano, Italy) and capillary column DB-FFAP (30 m 0.250 mm; 0.25 µm; Agilent Technologies S.p.A., Milano, Italy). The analysis conditions were as follows: 200 and 230 °C injector and detector temperatures, respectively; 1.5 mL/min constant flow of hydrogen as carrier gas; 1 µL injection volume; and 30:1 split ratio. The temperature program was 40 °C 5 min, after 60 °C at 10 °C/min 5 min, after 160 °C at 5 °C/min, after 200 °C at 3 °C min. The VFA in silage samples were identified with the aid of external standards and calculated through peak areas corrected by factors of response instrumental and using pivalic acid as an internal standard. The micro-filtered extract used for volatile organic compounds (VOC) analysis was diluted (1 + 9) with 8.0 mM H2SO4 in a vial and injected into HPLC for lactic acid determination. The HPLC system consisting of PU-2080 pump, an AS-2055 sampling system, and a UV-2070 detector. An organic acid analysis column (Amine^® HPX-87H Ion exchange column, 300 mm × 7.8 mm i.d., Bio-Rad, Hercules, CA, USA) was used at 35 °C with a mobile phase of 8.0 mM H2SO4 at 0.6 ml/min. The UV detector was set at 210 nm. The quantification of lactic acid was done using an external standard.
The NH3-N was determined from about 20 g of fresh samples in a slurry mix composed of 150 ml of distilled water and magnesium oxide (10 g/sample). The NH3-N content, expressed on a total nitrogen (TN) basis, was determined after steam distillation of this solution by the Kjeldahl method as reported above. Finally, the pH value was measured on the previously filtered water mixture.

Gallo A., Ghilardelli F., Atzori A.S., Zara S., Novak B., Faas J, & Fancello F. (2021). Co-Occurrence of Regulated and Emerging Mycotoxins in Corn Silage: Relationships with Fermentation Quality and Bacterial Communities. Toxins, 13(3), 232.

Publication 2021

Synthesis and Characterization of FAM-InsP5

Cited 3 times

Synthesis of FAM-InsP₅General chemistry experimental: All chemicals and solvents were supplied by Sigma–Aldrich and Alfa–Aesar. Unless otherwise stated, HPLC-grade solvents were used, and commercial reagents were used without further purification. Thin-layer chromatography (TLC) was performed on precoated plates (Merck TLC aluminium sheets silica 60 F₂₅₄) with detection by UV light or with phosphomolybdic acid in methanol or alkaline aqueous KMnO₄, followed by heating. Flash chromatography was performed on an ISCO CombiFlash R_f automated flash chromatography system with RediSep R_f disposable flash columns. Ion-exchange chromatography was carried out on Q Sepharose Fast Flow with a Pharmacia Biotech Gradifrac system and a P-1 pump, with elution at 5 mL min⁻¹ with gradients of aqueous triethylammonium bicarbonate (TEAB) buffer. Low-pressure reversed-phase chromatography was performed on Lichroprep RP-18 (Merck) with use of the Gradifrac system and elution at 5 mL min⁻¹ with gradients of acetonitrile in TEAB buffer (0.05 m). All water used in the purification of water-soluble polyphosphates was of MilliQ quality. During the manipulation of fluorescent compounds, light was excluded by covering reaction vessels, columns etc. with aluminium foil. RP-HPLC analyses of FAM-InsP₅ (5) were performed with a Waters 2695 Alliance module fitted with a Waters 2996 photodiode array detector (210–600 nm). The chromatographic system consisted of a Phenomenex Security Guard cartridge system for HPLC and a Phenomenex Gemini 5 μm C₁₈ 10 Å column (150×4.60 mm), with elution at 1 mL min⁻¹ with a gradient (5 % to 70 %) of acetonitrile in aqueous triethylammonium acetate (0.1 m) over 10 min, with detection at 254 nm. Proton ¹H NMR spectra were recorded with a Bruker Avance III (400 MHz) spectrometer. Proton chemical shifts are reported in ppm (δ) relative to internal tetramethylsilane (TMS, 0.0 ppm) or with the solvent reference relative to TMS employed as the internal standard ([D₆]DMSO: 2.50 ppm; D₂O: 4.79 ppm). ¹³C and DEPT spectra were recorded with a Bruker Avance III (100 MHz) spectrometer with complete proton decoupling. Carbon chemical shifts are reported in ppm (δ) relative to internal tetramethylsilane (TMS: 0.0 ppm) or with the solvent resonance relative to TMS employed as the internal standard ([D₆]DMSO: 39.51 ppm). ³¹P NMR spectra were recorded with Bruker Avance III (109 MHz and 162 MHz) spectrometers with complete proton decoupling. Phosphorus chemical shifts are reported in ppm (δ) relative to an H₃PO₄ (85 %) external standard (H₃PO₄: 0.0 ppm). Melting points were determined with a Reichert–Jung Thermo Galen Kofler block or a Stanford Research Systems Optimelt MPA100 automated melting point system and are uncorrected. Microanalysis was carried out at the University of Bath microanalysis service. Mass spectra were recorded at the SERC Mass Spectrometry Service Centre, Swansea, and at the University of Bath on VG Autospec or MicroTOF instruments.
1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-myo-inositol (6): Trimethyl orthoformate (100 mL), butanedione (25 mL, 285 mmol) and (±)-10-camphorsulphonic acid (0.5 g) were added to a stirred suspension of myo-inositol (25.0 g, 139 mmol) in MeOH (250 mL). The mixture was heated under N₂ at reflux for 96 h and then allowed to cool, giving a cherry-red suspension. The precipitate was filtered off, washed with MeOH (200 mL) and allowed to dry, giving crude diol 6 as a white solid (22.4 g, 85 % pure by ¹H NMR). This material was crystallised from boiling CHCl₃/MeOH (1:1, v/v, 650 mL) and dried under vacuum at 60 °C to give 6 as colourless crystals (15.4 g, 37.7 mmol, 27 %); m.p. >300 °C with sublimation and decomposition; R_f=0.24 (EtOAc); R_f=0.29 (CHCl₃/acetone 2:1); ¹H NMR (400 MHz, [D₆]DMSO): δ=1.17 (s, 6 H; CH₃), 1.18 (s, 6 H; CH₃), 3.13 (s, 6 H; OCH₃), 3.15 (s, 6 H; OCH₃), 3.25 (dt, ³J=5.6, 9.3 Hz, 1 H; H-5), 3.35 (dd, ³J=10.2, 2.4 Hz, 2 H; H-1, H-3), 3.67 (dd, ³J=9.8, 9.8 Hz, 2 H; H-4, H-6), 3.76 (dt, ³J=4.6, 2.4 Hz, 1 H; H-2), 4.99 (d, ³J=4.8 Hz, 1 H; OH-2), 5.05 ppm (d, ³J=5.6 Hz, 1 H; OH-5); ¹³C NMR (100 MHz, [D₆]DMSO): δ=17.64 (CH₃), 47.12 (OCH₃), 47.42 (OCH₃), 67.57 (C-2), 68.37 (C-1, C-3), 69.13 (C-5), 69.33 (C-4, C-6), 98.41 (BDA quaternary C), 98.97 ppm (BDA quaternary C); HRMS: m/z calcd for C₁₈H₃₂O₁₀: 431.1888 [M+Na]⁺; found: 431.1880; elemental analysis calcd (%) for C₁₈H₃₂O₁₀: C 52.93, H 7.90; found: C 52.6, H 7.92.
5-O-Benzoyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-myo-inositol (7): A solution of diol 6 (2.04 g, 5.00 mmol) in anhydrous pyridine (20 mL) was stirred at 0 °C under N₂. Benzoic anhydride (1.24 g, 5.5 mmol) was added, followed by a catalytic amount of DMAP (60 mg, 0.50 mmol). The cooling bath was removed, and the solution was allowed to reach room temperature. After 18 h, the solution was diluted with CH₂Cl₂ (200 mL), washed well with HCl (1.0 m, 2×250 mL) and saturated NaHCO₃ solution (100 mL) and then dried (MgSO₄) and concentrated under reduced pressure. The residue was purified by flash chromatography on silica (EtOAc in CH₂Cl₂, 0 to 40 %) to give the 5-O-benzoate ester 7 as a white solid (2.15 g, 4.19 mmol, 84 %); crystals from boiling EtOH, m.p. 292.5–295.5 °C; R_f=0.24 (CH₂Cl₂/EtOAc 5:1); ¹H NMR (400 MHz, CDCl₃): δ=1.19 (s, 6 H; CH₃), 1.32 (s, 6 H; CH₃), 2.44 (br s, 1 H; 5-OH), 3.13 (s, 6 H; OCH₃), 3.25 (s, 6 H; OCH₃), 3.72 (dd, ³J=10.2, 2.6 Hz, 2 H; H-1, H-3), 4.10 (t, ³J=2.6 Hz, 1 H; H-2), 4.26 (dd, ³J=10.1, 9.9 Hz, 2 H; H-4, H-6), 5.39 (t, ³J=9.9 Hz, 1 H; H-5), 7.41–7.45 (m, 2 H; meta-H of Bz), 7.55 (tt, ³J=7.4, 1.3 Hz, 1 H; para-H of Bz), 8.05–8.08 ppm (m, 2 H, ortho-H of Bz); ¹³C NMR (100 MHz, CDCl₃): δ=17.61 (CH₃), 17.64 (CH₃), 47.58 (OCH₃), 48.00 (OCH₃), 67.28 (C-4, C-6), 68.63 (C-1, C-3), 68.95 (C-2), 70.96 (C-5), 99.33 (BDA quaternary C), 100.13 (BDA quaternary C), 128.37 (Bz meta-C), 129.59 (Bz ortho-C), 130.40 (Bz ipso-C), 132.76 (Bz para-C), 165.16 ppm (Bz C=O); HRMS: m/z calcd for C₂₅H₃₆O₁₁: 535.2150 [M+Na]⁺; found: 535.2153; elemental analysis calcd for C₂₅H₃₆O₁₁: C 58.58, H 7.08; found: C 58.5, H 7.14.
5-O-Benzoyl-2-O-cyanomethyl-1,6:3,4-bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-myo-inositol (8): Sodium hydride (468 mg of a 60 % suspension in mineral oil, 11.7 mmol) was added under N₂ to a suspension of 7 (2.00 g, 3.90 mmol) in dry acetonitrile (20 mL). The suspension was stirred at room temperature for 30 min. The suspension first became almost clear, and then thickened as evolution of gas ceased. The suspension was then cooled to −30 °C (acetonitrile/solid CO₂ bath), and bromoacetonitrile (1.5 mL, 23 mmol) was added dropwise over 2 min. The suspension was stirred at −20 °C for 3.5 h and then allowed to reach room temperature overnight. The resulting brown suspension was concentrated under reduced pressure to give a solid residue, which was dispersed in dichloromethane (100 mL in portions with use of an ultrasound bath) and filtered through Celite, leaving a pale yellow solution. The solution was concentrated, and the residue was purified by flash chromatography (EtOAc in CH₂Cl₂, 0 to 50 %) to give 8 as a white solid (1.83 g, 3.32 mmol, 85 %); m.p. 264–266 °C (from EtOH); R_f=0.54 (CH₂Cl₂/EtOAc 5:1); ¹H NMR (400 MHz, CDCl₃): δ=1.17 (s, 6 H; CH₃), 1.30 (s, 6 H; CH₃), 3.13 (s, 6 H; OCH₃), 3.25 (s, 6 H; OCH₃), 3.76 (dd, ³J=10.3, 2.4 Hz, 2 H; H-1, H-3), 4.01 (t, ³J=2.4 Hz, 1 H; H-2), 4.14 (dd, ³J=10.2, 10.0 Hz, 2 H; H-4, H-6), 4.69 (s, 2 H; CH₂CN), 5.37 (t, ³J=9.8 Hz, 1 H; H-5), 7.42–7.45 (m, 2 H; meta-H of Bz), 7.55 (tt, ³J=7.2, 1.2 Hz, 1 H; para-H of Bz), 8.05–8.08 ppm (m, 2 H; ortho-H of Bz); ¹³C NMR (100 MHz, CDCl₃): δ=17.57 (CH₃), 17.58 (CH₃), 47.64 (OCH₃), 48.09 (OCH₃), 56.77 (OCH₂CN), 67.43 (C-4, C-6), 68.68 (C-1, C-3), 71.03 (C-5), 76.22 (C-2), 99.27 (BDA quaternary C), 99.97 (BDA quaternary C), 116.28 (OCH₂CN), 128.39 (Bz meta-C), 129.62 (Bz ortho-C), 130.29 (Bz ipso-C), 132.83 (Bz para-C), 165.16 ppm (Bz C=O); HRMS: m/z calcd for C₂₇H₃₇NO₁₁: 574.2259 [M+Na]⁺; found: 574.2269; elemental analysis calcd for C₂₇H₃₇NO₁₁: C 58.79, H 6.76, N 2.54; found: C 58.4, H 6.85, N 2.48.
1,6:3,4-Bis-[O-(2,3-dimethoxybutane-2,3-diyl)]-2-O-[2-(2,2,2-trifluoroacetylamino)ethyl]-myo-inositol (9): A solution of 8 (1.78 g, 3.23 mmol) in dry THF (25 mL) was added dropwise over 30 min, under N₂ at 0 °C, to a solution of LiAlH₄ in THF (10 mL of a 1.0 m solution, 10 mmol). The mixture was stirred at room temperature for a further 1 h and then quenched by careful addition of a saturated solution of potassium sodium tartrate (75 mL). Ether (75 mL) was then added, and the mixture was stirred vigorously for 30 min until two distinct layers formed. The ether layer was separated, and the aqueous layer was re-extracted with ether (2×100 mL). The combined organic extracts were dried (MgSO₄) and concentrated to give the crude amine (1.8 g, R_f=0.16 in CH₂Cl₂/MeOH/NH₃, 200:20:1) as a foam, which was taken up in dry THF (10 mL) and stirred with ethyl trifluoroacetate (2 mL, 8.4 mmol) at room temperature. After 2 h, the solution was concentrated, and the residue was purified by flash chromatography (ethyl acetate in petroleum ether, 0 to 100 %) to give 9 as a white solid (1.16 g, 2.12 mmol, 66 %); m.p. 206–208 °C (from EtOAc/petroleum ether); R_f=0.25, (CH₂Cl₂/EtOAc 1:1); ¹H NMR (400 MHz, CDCl₃): δ=1.29 (s, 6 H; CH₃), 1.32 (s, 6 H; CH₃), 2.62 (br s, 1 H; 5-OH), 3.24 (s, 6 H; OCH₃), 3.28 (s, 6 H; OCH₃), 3.54 (dd, ³J=10.2, 2.6 Hz, 2 H; H-1, H-3), 3.54–3.57 (m, 2 H; OCH₂CH₂N), 3.62 (t, ³J=2.6 Hz, 1 H; H-2), 3.65 (td, ³J=9.5, 2.1 Hz, 1 H; H-5), 3.81 (dd, ³J=5.1, 4.7 Hz, 2 H; OCH₂CH₂N), 3.94 (dd, ³J=10.0, 9.8 Hz, 2 H; H-4, H-6), 7.32 ppm (br t, 1 H; NHC(O)CF₃); ¹³C NMR (100 MHz, CDCl₃): δ=17.50 (CH₃), 17.69 (CH₃), 39.52 (OCH₂CH₂N), 47.96 (OCH₃), 48.06 (OCH₃), 68.47 (C-1, C-3), 69.26 (C-4, C-6), 70.11 (C-5), 70.80 (OCH₂CH₂N), 77.46 (C-2), 99.27 (BDA quaternary C), 99.89 (BDA quaternary C), 115.99 (q, ²J_H,F=288 Hz; CF₃), 157.24 ppm (q, ³J_H,F=37 Hz; C(O)CF₃); HRMS: m/z calcd for C₂₂H₃₆F₃NO₁₁: 570.2133 [M+Na]⁺; found: 570.2151; elemental analysis calcd for C₂₂H₃₆F₃NO₁₁: C 48.26, H 6.63, N 2.56; found: C 48.1, H 6.52, N 2.41.
2-O-[2-(2,2,2-Trifluoroacetylamino)ethyl]-myo-inositol 1,3,4,5,6-pentakis(dibenzylphosphate) (10): Compound 9 (450 mg, 0.822 mmol) was dissolved in aqueous TFA (95 %, 10 mL). The solution was stirred at room temperature for 20 min and then concentrated by evaporation under reduced pressure. Ethanol was added and evaporated several times to remove traces of TFA. The solid pentaol product (R_f=0.20, CH₂Cl₂/MeOH 3:1) was dried under vacuum for 16 h and then suspended in dry dichloromethane (10 mL). The suspension was stirred at room temperature under N₂, and 5-phenyltetrazole (900 mg, 6.16 mmol) was added, followed by bis(benzyloxy)diisopropylaminophosphine (1.7 mL, 4.9 mmol). The mixture was stirred at room temperature for 2 h, after which time a clear solution remained. The solution was cooled to −78 °C, and 3-chloroperoxybenzoic acid (57 %, 2.5 g, 8.2 mmol) was added in portions over 1 min. A precipitate formed during the oxidation reaction. The resulting suspension was allowed to warm to room temperature and diluted with EtOAc (50 mL), giving a clear solution. The solution was washed with aqueous sodium sulfite solution (10 %, 2×50 mL), dried over MgSO₄ and concentrated, leaving an oily residue, which was purified by flash chromatography with elution with acetone in dichloromethane (0 to 50 %) to give 10 (1.17 g, 0.722 mmol, 88 %) as a colourless oil; R_f=0.20 (CH₂Cl₂/acetone 5:1); ¹H NMR (400 MHz, CDCl₃): δ=3.31–3.34 (m, 2 H; OCH₂CH₂N), 3.69 (t, ³J=4.6 Hz, 2 H; OCH₂CH₂N), 4.25 (ddd, ³J_H,H=9.5, 2.2 Hz, ³J_H,P=9.5 Hz, 2 H; H-1, H-3), 4.40–4.49 (m, 2 H; H-2, H-5), 4.92–5.03 (m, 22 H; CH₂Ph, H-4, H-6), 7.15–7.29 (m, 50 H; Ph), 8.06 ppm (broad, 1 H; amide NH); ¹³C NMR (100 MHz, CDCl₃): δ=40.09 (OCH₂CH₂N), 69.59–69.96 (with ³J_C,P couplings; OPOCH₂Ph), 71.04 (OCH₂CH₂N), 74.67, 75.24, 75.49 and 75.86 (broad signals with J_C,P couplings; inositol ring CH), 115.95 (¹J_C,F=288 Hz; CF₃), 127.96–128.71 (CH of Ph), 135.21–135.80 (ipso-C of POCH₂Ph), 157.62 ppm (²J_C,F=36.8 Hz; C(O)CF₃); ¹⁹F NMR (376 MHz, CDCl₃): δ=−75.14 ppm; ³¹P NMR (162 MHz, CDCl₃): δ=−2.05 (2 P), −1.45 (1 P), −1.43 ppm (2 P); HRMS: m/z calcd for C₈₀H₈₁F₃NO₂₂P₅: 1618.3818 [M]⁻; found: 1618.3788.
2-O-(2-Aminoethyl)-myo-inositol 1,3,4,5,6-pentakisphosphate (4): Palladium hydroxide on activated charcoal (Fluka, 20 %, 50 % water, 100 mg) was added to a solution of 10 (380 mg, 0.235 mmol) in MeOH (30 mL) and deionised water (8 mL). The suspension was stirred vigorously under hydrogen (balloon) for 16 h. The catalyst was removed by filtration through a PTFE syringe filter (0.2 μm) to give a colourless solution, which was neutralised by addition of N,N-diisopropylethylamine (DIPEA, 0.5 mL). The solvents were then removed by evaporation under reduced pressure. A ¹H NMR spectrum of the product in D₂O at this stage showed no residual aromatic signals, thus indicating that hydrogenolysis was complete. The product was redissolved in deionised water (1 mL), excess DIPEA (1 mL) was added, and the solution was heated under N₂ at 60 °C for 20 h. The solution was concentrated, and the residue was redissolved in deionised water and lyophilised to give the diisopropylethylammonium salt of 4 as a fawn solid (325 mg); ¹H NMR (400 MHz, D₂O): δ=1.18–1.22 (m, 75 H; DIPEA CH₃), 3.07 (q, ³J=7.4 Hz,10 H; DIPEA CH₂), 3.13 (t, ³J=5.1 Hz, 2 H; OCH₂CH₂NH₃⁺), 3.58 (heptet, ³J=6.7 Hz,10 H; DIPEA CH), 3.96 (t, ³J=5.1 Hz, 2 H; OCH₂CH₂NH₃⁺), 4.02–4.08 (m, 3 H; H-1, H-3, H-5), 4.11 (t, ³J=2.5 Hz, 1 H; H-2), 4.38 ppm (q, ³J=9.7 Hz, 2 H; H-4, H-6); ¹³C NMR (100 MHz, D₂O): δ=12.11 (DIPEA CH₂CH₃), 16.22 (DIPEA CH(CH₃)₂), 17.69 (DIPEA CH(CH₃)₂), 39.52 (OCH₂CH₂NH₃⁺), 42.51 (DIPEA CH₂CH₃), 54.32 (DIPEA CH(CH₃)₂), 69.37 (OCH₂CH₂NH₃⁺), 73.89 and 76.13 (C-1, C-3, C-4, C-6), 77.27 (C-5), 79.17 ppm (C-2); ³¹P NMR (162 MHz, D₂O): δ=−0.39 (2 P), 0.63 (2 P), 0.80 ppm (1 P; P-5); HRMS: m/z calcd for C₈H₂₂NO₂₁P₅: 621.9300 [M]⁻; found: 621.9311.
This material was used in subsequent conjugation reactions, but for biological evaluations of 4, a portion was purified by ionexchange chromatography on Q Sepharose Fast Flow resin with elution with TEAB (0 to 2.0 m) to give the triethylammonium salt of 4, which was accurately quantified by total phosphate assay.
2-O-[2-(5-Fluoresceinylcarboxy)aminoethyl]-myo-inositol 1,3,4,5,6-pentakisphosphate (5): Dry DIPEA (10 μL) was added to a suspension of 4 (20 mg DIPEA salt, 14 μmol) in dry propan-2-ol. Solid 5-carboxyfluorescein NHS ester[14 ] (13 mg, 28 μmol) was added to the resulting clear solution, followed by further dry DIPEA (60 μL). The flask was covered in foil to exclude light, and the reaction mixture was stirred under N₂ at 60 °C for 24 h and was then allowed to cool and concentrated under reduced pressure. The residue was dissolved in TEAB (0.05 m, pH approx. 7.5, 5 mL) and applied to a column of Q Sepharose Fast Flow resin (bicarbonate form, 70 mm×20 mm). The column was washed well with milliQ water, followed by TEAB (0.8 m, pH approx. 7.8) until the eluent ran colourless. This required approximately 400 mL of buffer. The column was then eluted with a gradient of TEAB (0.8 to 2.0 m, over 300 mL), with collection of 10 mL fractions. A fluorescent product eluted at high buffer concentration (>1.6 m TEAB). Fractions containing this product were combined and concentrated to give an orange solid, which was re-dissolved in TEAB (0.05 m, pH approx. 7.5, 5 mL) and applied to a small column (100 mm×10 mm) of Lichroprep RP-18. The column was eluted with a gradient of acetonitrile (0 to 30 % in 0.05 m TEAB over 300 mL), with collection of 10 mL fractions. Fluorescent fractions were combined and concentrated to leave a solid residue, which was re-dissolved in milliQ water and lyophilised to give the pure triethylammonium salt of 5 (containing 4.5 Et₃NH⁺ per equiv of 5) as a fluffy orange solid (16 mg, 11 μmol, 79 %); ¹H NMR (400 MHz, D₂O): δ=1.12 [t, ³J=7.5 Hz, approx. 40 H; (CH₃CH₂)₃NH⁺], 3.03 [q, ³J=7.5 Hz, approx. 27 H; (CH₃CH₂)₃NH⁺], 3.61 (t, ³J=5.1 Hz, 2 H; OCH₂CH₂NH), 3.97 (t, ³J=5.1 Hz, 2 H; OCH₂CH₂NH), 4.04–4.14 (m, 3 H; H-1, H-3, H-5), 4.19 (br s, 1 H; H-2), 4.41 (dt, ³J_H,P=9.4 Hz, ³J_H,H=9.4 Hz, 2 H; H-4, H-6), 6.65–6.68 (m, 4 H; fluorescein H-2′, H-4′, H-5′, H-7′), 6.99 (d, ³J=9.7 Hz, 2 H; fluorescein H-1′, H-8′), 7.43 (d, ³J=8.2 Hz, 1 H; fluorescein H-7), 8.13 (dd, ³J=8.2 Hz, ⁴J=1.9 Hz, 1 H; fluorescein H-6), 8.31 ppm (d, ⁴J=1.9 Hz, 1 H; fluorescein H-4); ¹³C NMR (100 MHz, D₂O): δ=8.14 [(CH₃CH₂)₃NH⁺], 40.34 (OCH₂CH₂NH), 46.53 [(CH₃CH₂)₃NH⁺], 71.67 (OCH₂CH₂NH), 74.10 and 76.29 (C-1, C-3, C-4, C-6), 77.49 (C-5), 78.62 (C-2), 102.64, 112.66, 116.55, 126.60, 127.77, 130.97, 131.45, 132.48, 135.97, 144.62, 155.23, 165.24, 169.21 (C=O), 170.98 ppm (C=O); ³¹P NMR (109 MHz, CD₃OD): δ=0.97 (2 P), 1.89 (2 P), 2.21 ppm (1 P; P-5); HRMS: m/z calcd for C₂₉H₃₁NO₂₇P₅⁻: 979.9777 [M]⁻; found: 979.9741; analytical RP HPLC: t_R=4.40 min (see General Chemistry Experimental).
Cell lines and cell culture: NCI-H1299 (H1299), HCT-116, CaCo-2, MDA-MDB-231, MCF-7 and Mevo cells were purchased from ATCC. Skin fibroblasts cells were a gift from Ulla Kasten-Pisula (Hamburg, Germany), and PT4323 (primary tumour) and LN2343 (the corresponding lymph node metastasis) were both freshly isolated from primary lung adenocarcinomas (for details see ref. [8 (link)]). The well-established cell line H1299 derives from a lymph node metastasis of lung adenocarcinoma cells. HCT-116 and CaCo-2 are colon cancer cells, MDA-MDB-231 and MCF-7 are breast cancer cells, and Mevo are melanoma cells. The cell lines MDA-MDB-231, NCI-H1299 and HCT-116 were cultured in Dulbecco's modified Eagle's medium (DMEM), Mevo and fibroblasts were grown in RPMI, PT4323 and LN2343 in RPMI with supplements (see ref. [8 (link)]) and CaCo-2 in MEM alpha medium. All media were supplemented with foetal calf serum (FCS, 10 %, v/v), l-glutamine (4 mm), streptomycin (100 μg mL⁻¹) and penicillin (100 U mL⁻¹) and were purchased from Invitrogen.
Analysis of cellular uptake of FAM-InsP₅ (5) in intact cells by fluorescence microscopy: Cells were grown on poly-l-lysine-covered cover slips to 20, 50 or 80 % confluence, and 5 or fluorescein (TEA⁺ salt in each case, 20 μm) as control (both diluted in deionised water) was added. After incubation for different times, the cells were washed three times with phosphate saline (PBS), fixed with paraformaldehyde (3 %), washed again three times with PBS and finally embedded in Fluoromount-G (Southern Biotech, Birmingham, Alabama. USA). Uptake of 5 was analysed by performing z-stacks (about 50 stacks per image of 1 to 1.5 μm in size) of bright and fluorescence light with a BZ-9000 E microscope from Keyence (Neu Isenburg, Germany). After overlay of these z-stacks, a 3D analysis was performed (software: BZ-H1RE), and the position of 5 was determined in xz- and in xy-layers of single stacks. Positioning of 5 in the middle cell layers was defined as cellular uptake, whereas accumulation in the first layers was defined as cell surface localisation of 5. The micrographs shown here represent focus stackings of bright and fluorescence light overlays by using software (BZ-H1RE) that selects the sharpest areas from multiple frames. Every experiment was performed in triplicate, and at least 100 cells were analysed per experiment.
Analysis of cellular uptake of FAM-InsP₅ (5) in lysed cells by fluorescence photometry: H1299 cells grown to about 80 % confluence in 10 cm dishes were treated with 5 (25 μm) for 3 h. The cells were then washed five times with PBS, MPER buffer (1.1 mL) was added, the cells were scraped, and the suspension was frozen in N₂ and thawed twice. The resulting suspension was diluted 1:1 with PBS, and the fluorescence was analysed with a Tecan Infinitive M100 fluorescence reader at excitation 490 nm and emission 535 nm. To prepare a standard curve, different concentrations of 5 were added to untreated lysed cells and, after cautious mixing, the fluorescence of the standards was measured in parallel to the samples as well as to the washing fractions. To analyse bleaching, a solution of 5 was added to cell suspension or to PBS, and fluorescence was analysed as above over a time period of 3 h. Under both sets of conditions (cell suspension and PBS) we measured 20 % loss by bleaching.
Immunofluorescence: Cells preincubated with 5 for 16 h in chamber slides were washed twice with PBS, fixed with paraformaldehyde (3 %) for 10 min, washed three times with PBS and treated with Triton-100 (0.3 %) for 5 min at RT. After washing of the cells three times with PBS they were blocked in BSA/PBS (Sigma—Aldrich, 2.5 %) for 20 min, incubated with antibodies against early endosome antigen 1 (EEA1; Abcam, ab2900, Cambridge, UK) or lysosome-associated membrane protein-2 (LAMP-2; Santa Cruz #sc-5571), respectively, at a dilution of 1:200 in BSA/PBS (0.7 %, w/v) for 16 h at 8 °C. After having been washed again three times with PBS, the cells were finally treated with anti-rabbit secondary antibodies coupled to Alexa Fluor 568 at a dilution of 1:1000 for 1 h at 22 °C. After the cells had been washed with PBS, images were captured on a fluorescence microscope (Keyence BZ-9000).

Riley A.M., Windhorst S., Lin H.Y, & Potter B.V. (2013). Cellular Internalisation of an Inositol Phosphate Visualised by Using Fluorescent InsP5. Chembiochem, 15(1), 57-67.

Publication 2013

Neurochemical Profiling via HPLC-EC

Cited 2 times

Extracellular DA and 5-HT levels were analyzed by HPLC with electrochemical detection. Chromatography was performed using an Ultimate 3000 System (Dionex, USA), electrochemical detector Coulochem III (model 5300; ESA, USA) with a 5020 guard cell, a 5040 amperometric cell, and a Hypersil Gold C18 analytical column (3 μm, 100 × 3 mm; Thermo Fisher Scientific, USA). The mobile phase consisted of 0.1 M KH₂PO₄ buffer at pH 3.8, 0.5 mM Na₂EDTA, 100 mg/L 1-octanesulfonic acid sodium salt, and 2% methanol. The flow rate during analysis was set at 0.6 mL/min, and the applied potential of a guard cell was 600 mV, whereas the amperometric cell was 300 mV with a sensitivity set at 10 nA/V. The chromatographic data were processed by Chromeleon v.6.80 (Dionex) software package. The detection limit in dialysates was 0.002 pg/10 μL for DA and 0.01 pg/10 μL for 5-HT.
Extracellular levels of ACh were analyzed by UHPLC with electrochemical detection. The ACh analysis is based on ion-pairing HPLC separation, followed by on-line enzymatic conversion of ACh to hydrogen peroxide and detection on a Pt working electrode (SenCell with 2 mm Pt working electrode) and HyREF reference electrode at the potential of 200 mV. Chromatography was performed using the ALEXYS Neurotransmitter Analyzer, a DECADE Elite electrochemical detector, AS 110 Autosampler, and LC 110 pump (Antec Leyden B. V., Zoeterwoude, The Netherlands). ACh as positively charged was separated on Acquity UPLC HSS T3 analytical column (1.8 μm, 1 × 50 mm; Waters, Milford, MA, USA). After separation, ACh passed through an immobilized enzyme reactor AChE/ChOx IMER (AC-ENZYM II, 1 × 4 mm, Eicom, Kyoto, Japan). The mobile phase was composed of 50 mM monosodium orthophosphate buffer adjusted to pH 7.8, 0.5 mM Na₂EDTA, 2.8 g/L 1-octanesulfonic acid sodium salt, and 0.5 mM tetramethylammonium chloride. The flow rate during analysis was set to 0.05 mL/min. The chromatographic data were processed by the CLARITY v.6.2.0.208 (DataApex Ltd.) chromatography software run on a personal computer. The detection limit of ACh in dialysates was 1.1 nM.
Glutamate levels in the extracellular fluid were measured electrochemically after derivatization with OPA/sulfite reagent to form isoindole-sulfonate derivative (Rowley et al. 1995 (link)). Chromatography was performed using an Ultimate 3000 pump (Dionex), LC-4B amperometric detector with a cross-flow detector cell (BAS), and an HR-80 column (3 μm, 80 × 4.6 mm; ESA, USA). The mobile phase was composed of 100 mM monosodium orthophosphate at pH 4.6 and 4% methanol. The flow rate during analysis was set to 1 mL/min and the applied potential of a 3-mm glassy carbon electrode was set at + 600 mV at a sensitivity of 5 nA/V. The glutamate-derivative peak was compared with the respective standard, and the data were processed using the Chromax 2005 (Pol-Lab, Poland) software. The detection limit of glutamate in dialysates was 0.03 ng/10 μL.

Herian M., Skawski M., Wojtas A., Sobocińska M.K., Noworyta K, & Gołembiowska K. (2021). Tolerance to neurochemical and behavioral effects of the hallucinogen 25I-NBOMe. Psychopharmacology, 238(8), 2349-2364.

Publication 2021

Acids Alkanesulfonates Buffers Carbon Cells Chromatography DA10 Dialysis Solutions Enzymes Enzymes, Immobilized Extracellular Fluid Glutamate Gold High-Performance Liquid Chromatographies Hypersensitivity Isoindoles Methanol Neurotransmitters Orthophosphate Pain Peroxide, Hydrogen Sodium Sodium Chloride sodium polymetaphosphate Sulfites tetramethylammonium chloride

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Fresh makal obtained from the local market of the municipality of Kimbilá, Yucatán, Mexico (longitude 20°17'45" and latitude -89°05'05") was used. Makal tubers were harvested during the months of July and September 2022. The rhizomes were cleaned and stored in refrigeration at 4 ºC until use. The tubers were processed based on the method by Estrada et al. (14 (link)), with some modifications. Rhizomes were peeled, cut into 3-cm cubes and soaked for 30 min in a sodium hydrogen sulfite solution (1.5 g/L; (m(sample)/V(solution))=1:3). Cubes were then ground in a blender (Oster 465-42; Sunbeam Products Inc., Delray Beach, FL, USA) and the resulting mass was suspended in a sodium hydrogen sulfite solution (1.5 g/L; φ(sample,solution)=0.5). To remove mucilaginous material, the mixture was centrifuged twice at 1100×g for 12 min (Mistral 3000i centrifuge; SpectraLab Scientific Inc., Markham, ON, Canada) and the supernatant was discarded. The precipitate was suspended again with sodium hydrogen sulfite and filtered through 80 mesh (177 μm) in laboratory sieves (Cole-Parmer, Vernon Hills, IL, USA) to remove fiber. The filtrate was left to settle at 4 °C for 24 h. When phase separation was observed, the supernatant was removed by siphoning and the precipitate was washed with distilled water and centrifuged at 1100×g for 12 min (Mistral 3000i; SpectraLab Scientific Inc.). The obtained starch was dried in a convection oven (Thermo Fisher Scientific Inc., Waltham, MA, USA) at 55 °C for 24 h, milled in a laboratory mill (Ciclotec; Tecator, Stockholm, Sweden) to obtain a powder that could pass through 100 mesh (149 µm) and finally stored until further use.

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A drying and rehydration method was used for the VA preparation. DDAB-at a concentration of 10 mM-was dissolved in acetone by sonication. The resulting solution was poured into a vial, and acetone was evaporated initially under nitrogen gas and then completely under a vacuum. After evaporation, a thin film remained on the wall of the vial. The thin film was hydrated with deionized water or aqueous solutions containing reactants of 2 mL; the solutions used for rehydration are explained in the next paragraph. The rehydration was performed at 50 • C for 1-2 h. The resulting suspension was shaken gently by hand and then treated as a VA suspension.
Three types of liquid were used for rehydration. The first type was deionized water. The second solution was a pH oscillator solution containing sodium bromate (0.2 M), manganese(II) sulfate pentahydrate (0.0033 M), sodium hydrogen sulfite (0.0033 M), and sodium sulfite (0.033 M) [33] (link). The third solution was a mixture of the pH oscillator solution and phosphate buffer. The mixing ratio was denoted as 1/n, which means that the volumetric ratio was 1(phosphate buffer)/n(pH oscillator solution). A pH indicator (BTB) was added to the solutions as required.

Shimada M., Someya R., Okamoto Y., Yamamoto D., & Shioi A. (2024). The Reversible Transformation of a Vesicular Aggregate in Response to a pH Oscillation. Processes, 12(3), 514-514.

Publication 2024

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More about "Hydrogen sulfite"

Hydrogen sulfite, also known as bisulfite, is a versatile chemical compound with the formula HSO3−.
It is widely used in various industries and applications, including food preservation, water treatment, and pharmaceuticals.
Closely related to sodium sulfite (Na2SO3) and sodium hydrogen sulfite (NaHSO3), hydrogen sulfite acts as a reducing agent, antioxidant, and preservative, making it a valuable asset in diverse contexts.
Researchers studying hydrogen sulfite will find that PubCompare.ai can optimize their work by helping them identify the most accurate and reproducible protocols from the literature, pre-prints, and patents.
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Hydrogen sulfite's applications extend beyond its core use as a chemical reagent.
It can be used in conjunction with other compounds, such as sodium hydroxide, hydrogen peroxide, methanol, hydrochloric acid, DMSO, and acetonitrile, to create various solutions and mixtures for specific purposes.
These synergistic interactions often play a crucial role in the development of new applications and the optimization of existing ones.
By leveraging the insights and tools provided by PubCompare.ai, researchers can streamline their hydrogen sulfite studies, ensuring they have access to the most reliable and effective protocols.
This data-driven approach can lead to breakthroughs in food preservation, water purification, pharmaceutical formulations, and other areas where hydrogen sulfite's unique properties are exploited.