Natural abundance 15N NMR using a DEPT pulse sequence was employed to follow the curing of urea-formaldehyde resin in the presence of wood fiber, fiber extracts and acid or base. The advantages of 15N NMR, large range chemical shifts, simplification of spectra and lack of interference by additives, can be exploited. The disadvantages of low sensitivity and long relaxation delays are offset by using a cross-polarization technique.
Received: 25 November 2002; Accepted: 16 April 2003; Published: 02 July 2003
A method for the simultaneous determination in milk of the 5′‑mononucleotides adenosine 5′‑monophosphate, cytidine 5′‑monophosphate, guanosine 5′‑monophosphate, inosine 5′‑monophosphate and uridine 5′‑monophosphate and their corresponding nucleosides is described. Following deproteinisation, the sample extract was analysed by reversed-phase liquid chromatography, whereby chromatographic separation was achieved using a polymer grafted silica C18 column, gradient elution with a simple binary mobile phase and UV detection by photodiode array. Performance parameters included recoveries of 95.5–105.2% and precision evaluated as 3.42–6.38% relative standard deviation. The described technique has been applied to the analysis of bovine and human milk, a range of commercial bovine milk-based infant and follow-on formulas, a seasonal study of skim milk powders and an assessment of alkaline phosphatase influence on nucleotide retention.
Received: 26 April 2006; Accepted: 1 August 2006; Published: 30 November 2006
Nucleotides and nucleosides play important roles as structural units in nucleic acids, as co‑enzymes in biochemical pathways, and as sources of chemical energy. Milk contains a complex mixture of nucleotides, nucleosides, and nucleobases, and because of the reported differences in their relative levels in bovine and human milks, pediatric formulas are increasingly supplemented with nucleotides. Liquid chromatography is the dominant analytical technique used for the quantitation of nucleospecies and is commonly applied using either ion-exchange, reversed-phase, or ion-pair reversed-phase modes. Robust methods that incorporate minimal sample preparation and rapid chromatographic separations have been developed for routine product compliance analysis. This review summarizes the analytical techniques used to date in the analysis of nucleospecies in bovine and human milks and infant formulas.
Received: 15 February 2007; Accepted: 30 May 2007; Published: 01 September 2007
A simple and rapid method has been developed for routine compliance testing of lutein in pediatric formulas. Following a mild saponification procedure (70 °C for 10 min) demonstrated to be benign to lutein, lipophilic components were partitioned by a single extraction into hexane:diisopropyl ether (75:25 v/v) and concentrated in mobile phase. Baseline chromatographic separation of lutein and zeaxanthin (internal standard) was achieved using a C30 column and isocratic elution with methanol: dichloromethane (70:30 v/v). Lutein concentration was quantitated against zeaxanthin, which corrected for incomplete extraction recovery. Performance parameters assessed included recovery (101–108%) and repeatability (2.2% RSD). The method was applied to the analysis of lutein supplemented pediatric formulas, unsupplemented milk powders, and bovine and human milk.
Received: 10 December 2007; Accepted: 28 February 2008; Published: 08 May 2008
An RP‑HPLC method for the routine determination of supplemented 5′‑mononucleotides (uridine 5′‑monophosphate, inosine 5′‑monophosphate, adenosine 5′‑monophosphate, guanosine 5′‑monophosphate, and cytidine 5′‑monophosphate) in pediatric formulas and milk products is described. Following sample dissolution, potential interferences were removed by anion-exchange SPE. Chromatographic analyses were performed using a C18 stationary phase with gradient elution, UV detection, and quantitation by an internal standard technique. A single-laboratory validation was performed, with recoveries of 92–101% and repeatability RSDs of 1.0–2.3%. The method was optimized for the rapid, routine analysis of nucleotide-supplemented bovine milk-based infant and follow-on formulas.
Received: 16 August 2009; Accepted: 02 October 2009; Published: 01 May 2010
Bovine colostrum and milk samples were collected from two herds over the course of the first month post-partum, pooled for each herd by stage of lactation and total potentially available nucleosides were determined. Sample analysis consisted of parallel enzymatic treatments, phenylboronate clean‑up, and liquid chromatography to quantify contributions of nucleosides, monomeric nucleotides, nucleotide adducts, and polymeric nucleotides to the available nucleosides pool. Bovine colostrum contained high levels of nucleosides and monomeric nucleotides, which rapidly decreased as lactation progressed into transitional milk. Mature milk was relatively consistent in nucleoside and monomeric nucleotide concentrations from approximately the tenth day post-partum. Differences in concentrations between summer‑milk and winter‑milk herds were largely attributable to variability in uridine and monomeric nucleotide concentrations.
Received: 22 April 2010; Accepted: 19 July 2010; Published: 31 August 2010
show abstract
Natural abundance 15N NMR using a DEPT pulse sequence was employed to follow the curing of urea-formaldehyde resin in the presence of wood fiber, fiber extracts and acid or base. The advantages of 15N NMR, large range chemical shifts, simplification of spectra and lack of interference by additives, can be exploited. The disadvantages of low sensitivity and long relaxation delays are offset by using a cross-polarization technique.
Received: 25 November 2002; Accepted: 16 April 2003; Published: 02 July 2003
Journal Citation Paper Manuscriptshow abstract
A method for the simultaneous determination in milk of the 5′‑mononucleotides adenosine 5′‑monophosphate, cytidine 5′‑monophosphate, guanosine 5′‑monophosphate, inosine 5′‑monophosphate and uridine 5′‑monophosphate and their corresponding nucleosides is described. Following deproteinisation, the sample extract was analysed by reversed-phase liquid chromatography, whereby chromatographic separation was achieved using a polymer grafted silica C18 column, gradient elution with a simple binary mobile phase and UV detection by photodiode array. Performance parameters included recoveries of 95.5–105.2% and precision evaluated as 3.42–6.38% relative standard deviation. The described technique has been applied to the analysis of bovine and human milk, a range of commercial bovine milk-based infant and follow-on formulas, a seasonal study of skim milk powders and an assessment of alkaline phosphatase influence on nucleotide retention.
Received: 26 April 2006; Accepted: 1 August 2006; Published: 30 November 2006
Journal Citation Paper Manuscriptshow abstract
Nucleotides and nucleosides play important roles as structural units in nucleic acids, as co‑enzymes in biochemical pathways, and as sources of chemical energy. Milk contains a complex mixture of nucleotides, nucleosides, and nucleobases, and because of the reported differences in their relative levels in bovine and human milks, pediatric formulas are increasingly supplemented with nucleotides. Liquid chromatography is the dominant analytical technique used for the quantitation of nucleospecies and is commonly applied using either ion-exchange, reversed-phase, or ion-pair reversed-phase modes. Robust methods that incorporate minimal sample preparation and rapid chromatographic separations have been developed for routine product compliance analysis. This review summarizes the analytical techniques used to date in the analysis of nucleospecies in bovine and human milks and infant formulas.
Received: 15 February 2007; Accepted: 30 May 2007; Published: 01 September 2007
Journal Citation Paper Manuscript
show abstract
A simple and rapid method has been developed for routine compliance testing of lutein in pediatric formulas. Following a mild saponification procedure (70 °C for 10 min) demonstrated to be benign to lutein, lipophilic components were partitioned by a single extraction into hexane:diisopropyl ether (75:25 v/v) and concentrated in mobile phase. Baseline chromatographic separation of lutein and zeaxanthin (internal standard) was achieved using a C30 column and isocratic elution with methanol: dichloromethane (70:30 v/v). Lutein concentration was quantitated against zeaxanthin, which corrected for incomplete extraction recovery. Performance parameters assessed included recovery (101–108%) and repeatability (2.2% RSD). The method was applied to the analysis of lutein supplemented pediatric formulas, unsupplemented milk powders, and bovine and human milk.
Received: 10 December 2007; Accepted: 28 February 2008; Published: 08 May 2008
Journal Citation Paper Manuscript
show abstract
An RP‑HPLC method for the routine determination of supplemented 5′‑mononucleotides (uridine 5′‑monophosphate, inosine 5′‑monophosphate, adenosine 5′‑monophosphate, guanosine 5′‑monophosphate, and cytidine 5′‑monophosphate) in pediatric formulas and milk products is described. Following sample dissolution, potential interferences were removed by anion-exchange SPE. Chromatographic analyses were performed using a C18 stationary phase with gradient elution, UV detection, and quantitation by an internal standard technique. A single-laboratory validation was performed, with recoveries of 92–101% and repeatability RSDs of 1.0–2.3%. The method was optimized for the rapid, routine analysis of nucleotide-supplemented bovine milk-based infant and follow-on formulas.
Received: 16 August 2009; Accepted: 02 October 2009; Published: 01 May 2010
Journal Citation Paper Manuscript
show abstract
Bovine colostrum and milk samples were collected from two herds over the course of the first month post-partum, pooled for each herd by stage of lactation and total potentially available nucleosides were determined. Sample analysis consisted of parallel enzymatic treatments, phenylboronate clean‑up, and liquid chromatography to quantify contributions of nucleosides, monomeric nucleotides, nucleotide adducts, and polymeric nucleotides to the available nucleosides pool. Bovine colostrum contained high levels of nucleosides and monomeric nucleotides, which rapidly decreased as lactation progressed into transitional milk. Mature milk was relatively consistent in nucleoside and monomeric nucleotide concentrations from approximately the tenth day post-partum. Differences in concentrations between summer‑milk and winter‑milk herds were largely attributable to variability in uridine and monomeric nucleotide concentrations.
Received: 22 April 2010; Accepted: 19 July 2010; Published: 31 August 2010
Journal Citation Paper Manuscript