Roberto Rocchetti

University of Bologna, Bolonia, Emilia-Romagna, Italy

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Publications (12)40.04 Total impact

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    ABSTRACT: Amino acids are retained on the copper form and on the amino copper form of chitosan, especially aspartic acid, glutamic acid, tryptophan, and cysteine. The best conditions for collection and for elution are in phosphate buffers at pH 7 and 12, respectively. No leakage of copper occurs; the amino acids are recovered as copper complexes with a ratio of 1:2 copper: amino acid. Several advantages of chitosan over the resin Chelex are pointed out; namely, absence of swelling, great copper capacity. hydrophilicity, and porous structure.
    Separation Science and Technology 12/1978; 13(10):869-879. · 1.16 Impact Factor
  • R A Muzzarelli, G Barontini, R Rocchetti
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    ABSTRACT: Lysozyme has been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent. The best pH conditions for operating the chitosan columns have been determined and the best eluting agent was found to be a 2% solution of propylamine. The lysozyme activity was determined after reacting lysozyme with the product of glycolchitin and Remazol Brilliant Blue R. The recovery of lysozyme from chicken egg white yields lysozyme with 55% activity.
    Biotechnology and Bioengineering 02/1978; 20(1):87-94. · 4.16 Impact Factor
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    ABSTRACT: The separation of cobalt, nickel, and copper from manganese and iron is performed on chitosan columns in the presence of a reducing agent, preferably sulfite or ascorbic acid. The procedure is applied to recover valuable metals from manganese nodules after solubilization with sodium hydrogen sulfate at 215°C.
    Separation Science and Technology 02/1978; 13(2):153-163. · 1.20 Impact Factor
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    ABSTRACT: alpha-Chymotrypsin and acid phosphatase have been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent; the immobilized enzymes are active and their activity is much higher than for chitin-immobilized enzymes. The best pH conditions for operating chitosan columns have been determined and columns have been used to transform substrates in large amounts, with no decrease of activity or enzyme losses. Due to the nonconvalent interaction between chitosan and enzymes, the pure and active enzymes can be eventually recovered from the columns. The effects of metal ions, aldehydes, and salts are reported and discussed. Applications are foreseen in the food and biomedical sciences and industries.
    Biotechnology and Bioengineering 11/1976; 18(10):1445-54. · 4.16 Impact Factor
  • Riccardo A.A. Muzzarelli, Roberto Rocchetti
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    ABSTRACT: A new and rapid method is described for the determination of Mn, Co and Cu by atomic absorption with a graphite atomizer and deuterium compensation, on very small samples of whole blood and serum, with no preliminary manipulations. The metal concentrations in blood serum from healthy donors have been found to be Mn 9 +/- 4.3 ng ml ; Co 7.7 +/- 1.9 ng ml and Cu 1.2 +/- 0.16 mug ml .
    Talanta 09/1975; 22(8):683-5. · 3.51 Impact Factor
  • R A Muzzarelli, R Rocchetti
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    ABSTRACT: Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3.0 and 5.0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1.0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3-5 on sulphate-conditioned chitosan, and elution with 0.1M sulphuric acid/0.1M ammonium sulphate at pH 1.0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included.
    Talanta 12/1974; 21(11):1137-43. · 3.51 Impact Factor
  • Riccardo A.A. Muzzarelli, Roberto Rocchetti
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    ABSTRACT: The experimental conditions for the removal of ionic mercury from waters have been studied. Columns containing 1–15 g of chitosan were used to lower the mercury concentration from 1 to 0.02 ppm, with volume reduction factors of 2000 to 10,000. Recycling of columns was carried out with 10 mM potassium iodide solution: other inorganic and organic eluting agents were also studied. The analytical instrumental techniques employed were flameless atomic-absorption spectrometry and radiochemistry.
    Journal of Chromatography A 09/1974; 96(1):115-21. · 4.26 Impact Factor
  • R.A.A. Muzzarelli, R Rocchetti
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    ABSTRACT: The anion-exchange behaviour of chitosan toward metavanadate was studied in salt solutions at different pH values. Filtered and acidified sea water was passed through a 500-mg chitosan column. Vanadium was determined by atomic absorption spectrometry with a graphite furnace and a deuterium background corrector on 5-mg aliquots of the homogenized column. The method was assessed for the 0.2–12.0 μg V 1-1 interval on the basis of the linear response for proportional amounts of vanadium in saline solutions and sea water and in the absence of interferences from smoke during atomization. Two sea-water samples gave 0.71±0.09 and 0.52±0.04 μg V 1-1.
    Analytica Chimica Acta 07/1974; 70(2):283-9. · 4.52 Impact Factor
  • Riccardo A.A. Muzzarelli, Roberto Rocchetti
    Analytica Chimica Acta 06/1974; 70(2):465–468. · 4.52 Impact Factor
  • Riccardo A.A. Muzzarelli, Roberto Rocchetti
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    ABSTRACT: Copper in sea water was determined by passing 1 1 of persulphate-pretreated sea water through a 30×3 mm chitosan column, and eluting with 20 ml of a 1% solution of 1,10-phenanthroline, or with 20 ml of 1 M sulphuric acid. Copper was determined in the eluates by hot graphite atomic absorption spectrometry. The result for Adriatic sea water (Ancona, Italy) was 6.06±0.56 μg Cu 1−1. Diethylaminoethylcellulose, p-aminobenzylcellulose and Dowex A-1OO were also tested; Dowex A-100 collects only a minor part of the copper present in sea water.RésuméLe dosage du cuivre dans l'eau de mer a été effectué aprés passage d'un litre d'eau traitée au persulfate sur colonne de chitosane de 30×3 mm, et élution avec 20 ml de solution a 1% de 1,10-phénanthroline ou avec 20 ml d'acide sulfurique. La technique analytique est basée sur la spectrométrie d'absorption atomique, avec atomisation sur graphite et correction du fond a l'aide du compensateur au deutérium. Le résultat obtenu avec l'eau de l'Adriatique (prélevée à Ancone, Italie) est de 6,06±0.56 μg Cu 1−1, en accord avec les résultats d'autres auteurs. Des essais ont été également effectués sur diéthylaminoéthylcellulose. p-aminobenzylcellulose et sur résine Dowex A-100 (connue aussi comme A-1 ou Chelex); on a constaté que cette dernière ne peut fixer qu'une portion limitée du cuivre présent dans l'eau de mer.ZusammenfassungKupfer in Meerwasser wurde bestimmt, indem 1 1 des mit Persulfat vorbehandelten Meerwassers durch eine Chitosan-Säule von 30×3 mm gegeben und der von der Säule zurückgehaltene Anteil mit 20 ml 1%-iger 1,10-Phenanthrolin-Lösung oder mit 20 ml 1 M Schwefelsäure eluiert wurde. Das Kupfer wurde in den Eluaten mittels Atomabsorptionsspektrometrie unter Verwendung heissen Graphits bestimmt. Das Ergebnis bei adriatischem Meerwasser (Ancona, Italien) war 6.06±0.56 μg Cu 1−1. Diäthylaminoäthylcellulose, p-Aminobenzylcellulose und Dowex A-100 wurden ebenfalls geprüft; Dowex A-100 hält nur einen kleineren Teil des in Meerwasser vorhandenen Kupfers zurück.
    Analytica Chimica Acta 04/1974; 69(1):35-42. · 4.52 Impact Factor
  • R A Muzzarelli, C Nicoletti, R Rocchetti
    Ion exchange and membranes 02/1974; 2(1):67-9.
  • Riccardo A.A. Muzzarelli, Roberto Rocchetti
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    ABSTRACT: A comparative study of the chelating ability ofchitosan, p-aminobenzylcellulose and diethylaminoethylcellulose, for a number of metal ions is discussed. There is a strong interaction between molybdenum and these polymers in thiocyanate solutions and in sea water. By combining the sensitivity of graphite-furnace atomic absorption spectrometry with the efficiency of the selective collection of molybdenum on p-aminobenzylcellulose or chitosan at pH 2.5, it was possible to determine molybdenum in as little as 50 ml of sea water.RésuméUne étude comparative est effectuée sur le pouvoir chélatant de divers polyméres, chitosane, p-aminobenzylcellulose et diéthylaminoéthylcellulose, pour un certain nombre de métaux. On observe une forte interaction entre le molybdéne et ces polyméres, en milieu thiocyanate et dans l'eau de mer. On propose une méthode pour le dosage du molybdéne dans des échantillons d'eau de mer ne dépassant pas 50 ml.ZusammenfassungEine vergleichende Untersuchung der Chelatisierungsfähigkeit von Chitosan, p-Aminobenzylcellulose und Diäthylaminoäthylcellulose gegenüber einer Anzahl von Metallionen wird diskutiert. Eine starke Wechselwirkung tritt zwischen Molybdän und diesen Polymeren in Thiocyanatlösungen und in Meerwasser auf. Durch die wirksame, selektive Anreicherung von Molybdän an p-Aminobenzylcellulose oder Chitosan bei pH 2.5, anschliessende Elution mit Carbonat und Atomabsorptionsspektrometrie unter Verwendung einer Graphit-Heizvorrichtung war es möglich, Molybdän in nur 50 ml Meerwasser zu bestimmen.
    Analytica Chimica Acta 06/1973; 64(3):371-9. · 4.52 Impact Factor