title: Development of a novel cyanide-free method for analysis of vitamin B₁₂ in milk-based infant formula

authors: Li, Yanan

abstract: The analysis of vitamin B₁₂ in infant formulas requires the use of cyanide during the sample preparation process to convert the three unstable vitamers (hydroxocobalamin, methylcobalamin and adenosylcobalamin) to cyanocobalamin, the most stable form of vitamin B₁₂. The undesirable handling of cyanide for the analyst in the laboratory and the associated safety risk indicates a clear necessity for development of a cyanide-free method for vitamin B₁₂ analysis without compromising the analytical quality.
This doctoral research demonstrates the possibility of using cobalamin-derived α-ribazole to represent total vitamin B₁₂, since the α-ribazole exists in all vitamin B₁₂ forms removing the necessity for conversion. The absence of a commercial standard of α-ribazole required its in-house isolation from a cyanocobalamin standard. The α-ribazole was released through consecutive acidic hydrolysis and dephosphorylation by alkaline phosphatase. The freed α-ribazole was collected by boronate affinity chromatography and concentrated by lyophilisation. α-Ribazole was identified and characterised by nuclear magnetic resonance spectroscopy and liquid chromatography mass spectrometry to demonstrate its suitability as a standard. This protocol was optimised and adopted in the sample preparation for analysing vitamin B₁₂ in infant formulas. Several extra steps were added to eliminate or limit interferences, including protein denaturation and sugar removal using C₁₈ solid phase extraction. The final analyte was quantified using hydrophilic interaction liquid chromatography with fluorescence detection.
The single laboratory validation experiment showed that this cyanide-free method is fit for purpose. Analysis of various milk-based infant formulas and comparison with current procedure demonstrated no bias for vitamin B₁₂ analysis.

text: Development of a novel cyanide-free method for analysis of vitamin B₁₂ in milk-based infant formula The analysis of vitamin B₁₂ in infant formulas requires the use of cyanide during the sample preparation process to convert the three unstable vitamers (hydroxocobalamin, methylcobalamin and adenosylcobalamin) to cyanocobalamin, the most stable form of vitamin B₁₂. The undesirable handling of cyanide for the analyst in the laboratory and the associated safety risk indicates a clear necessity for development of a cyanide-free method for vitamin B₁₂ analysis without compromising the analytical quality.
This doctoral research demonstrates the possibility of using cobalamin-derived α-ribazole to represent total vitamin B₁₂, since the α-ribazole exists in all vitamin B₁₂ forms removing the necessity for conversion. The absence of a commercial standard of α-ribazole required its in-house isolation from a cyanocobalamin standard. The α-ribazole was released through consecutive acidic hydrolysis and dephosphorylation by alkaline phosphatase. The freed α-ribazole was collected by boronate affinity chromatography and concentrated by lyophilisation. α-Ribazole was identified and characterised by nuclear magnetic resonance spectroscopy and liquid chromatography mass spectrometry to demonstrate its suitability as a standard. This protocol was optimised and adopted in the sample preparation for analysing vitamin B₁₂ in infant formulas. Several extra steps were added to eliminate or limit interferences, including protein denaturation and sugar removal using C₁₈ solid phase extraction. The final analyte was quantified using hydrophilic interaction liquid chromatography with fluorescence detection.
The single laboratory validation experiment showed that this cyanide-free method is fit for purpose. Analysis of various milk-based infant formulas and comparison with current procedure demonstrated no bias for vitamin B₁₂ analysis.

year: 2023

title: The impact of immigration on child health: Experimental evidence from a migration lottery program

authors: Stillman, Steven

subjects: New Zealand

abstract: This paper uses a unique survey designed by the authors to compare migrant children who enter New Zealand through a random ballot with children in the home country of Tonga whose families were unsuccessful participants in the same ballots. We find that migration increases height and reduces stunting of infants and toddlers, but also increases BMI and obesity among 3- to 5-yr-olds. These impacts are quite large even though the average migrant household has been in New Zealand for less than 1 yr. Additional results suggest that these impacts occur because of dietary change rather than direct income effects. (JEL J61, I12, F22)

text: The impact of immigration on child health: Experimental evidence from a migration lottery program This paper uses a unique survey designed by the authors to compare migrant children who enter New Zealand through a random ballot with children in the home country of Tonga whose families were unsuccessful participants in the same ballots. We find that migration increases height and reduces stunting of infants and toddlers, but also increases BMI and obesity among 3- to 5-yr-olds. These impacts are quite large even though the average migrant household has been in New Zealand for less than 1 yr. Additional results suggest that these impacts occur because of dietary change rather than direct income effects. (JEL J61, I12, F22)

year: 2010

title: Sylvia’s place: Ashton-Warner as New Zealand educational theorist.

authors: Middleton, Sue

subjects: educational theorist

abstract: Sylvia Ashton-Warner’s New Zealand educational context has been – and continues to be – misrepresented as antithetical to her creative methods. Sue Middleton, a professor of education, locates Sylvia’s educational ideas within the national and international Progressive Education movement, indicating that key education officials in post-war New Zealand encouraged creativity and self-expression.

This chapter makes the case that, as a teacher, an educational writer and theorist, Sylvia Ashton-Warner grew in, and not in spite of New Zealand. My argument unfolds in two parts. The first reviews theoretical ideas in the local and international educational environment in which Sylvia lived and worked. Sylvia and Keith Henderson taught in what was referred to until 1946 as the Native School system (and from 1948 until its abolition in 1968 as the Maori Scholl system). They trained and began work as teachers during the Great Depression; and Sylvia began serious writing during World War Two. The war and the Native Scholl system interested in complex ways with the wider international Progressive Education movement and its promotion ‘from the top’ in New Zealand’s public schools. An overview of Progressive (or New ) Education, the changing theories of culture and race in the Native School system, and relations between these during World War Two, opens a wide-angled aperture through which to read Sylvia’s early writing.

text: Sylvia’s place: Ashton-Warner as New Zealand educational theorist. Sylvia Ashton-Warner’s New Zealand educational context has been – and continues to be – misrepresented as antithetical to her creative methods. Sue Middleton, a professor of education, locates Sylvia’s educational ideas within the national and international Progressive Education movement, indicating that key education officials in post-war New Zealand encouraged creativity and self-expression.

This chapter makes the case that, as a teacher, an educational writer and theorist, Sylvia Ashton-Warner grew in, and not in spite of New Zealand. My argument unfolds in two parts. The first reviews theoretical ideas in the local and international educational environment in which Sylvia lived and worked. Sylvia and Keith Henderson taught in what was referred to until 1946 as the Native School system (and from 1948 until its abolition in 1968 as the Maori Scholl system). They trained and began work as teachers during the Great Depression; and Sylvia began serious writing during World War Two. The war and the Native Scholl system interested in complex ways with the wider international Progressive Education movement and its promotion ‘from the top’ in New Zealand’s public schools. An overview of Progressive (or New ) Education, the changing theories of culture and race in the Native School system, and relations between these during World War Two, opens a wide-angled aperture through which to read Sylvia’s early writing.

year: 2009