title: A Reinvestigation of Salvarsan and Related Arsenic Chemistry.

authors: Lloyd, Nicholas

subjects: Salvarsan

abstract: In 1910 the first deliberately targeted search for a new chemotherapeutic agent came to fruition when Paul Ehrlich introduced Salvarsan for the treatment of syphilis. This thesis presents a detailed review of the history and literature leading up to and following on from Ehrlich’s discovery and thoroughly investigates the chemistry of Salvarsan and related species. A series of arylarsonic acids was prepared and fully characterised by electrospray mass spectrometry, NMR and X-ray crystallography for six examples. A detailed analysis of the hydrogen bonding in crystals of these molecules showed that they adopt several characteristic motifs which govern the packing in the crystals. Two of the examples containing NH2 groups crystallised as zwitterions while one NH2 containing example containing other bulky groups was is its molecular form. Salvarsan (cyclo 3-amino-4-hydroxyphenylarsenic(I)) was prepared by several different methods and analysed in detail using high resolution electrospray mass spectroscopy. This showed that Salvarsan consists of small cyclic species of the type (RAs)n where R is 3-NH2-4-OHC6H3 and n is three or greater. The dominant species in an aqueous solution of Salvarsan were found to be (RAs)3 and (RAs)5 . A detailed analysis is presented of impurities in Salvarsan prepared by different methods and also in a sample of original commercial Salvarsan. Mixtures of (RAs)n and (R’As)n exchange R groups in aqueous solution at room temperature, as shown by ESI-MS. ESI-MS studies are reported for the oxidation product of Salvarsan, RAs(OH)2 (commercially known as Mapharsen) and related As(III) compounds. Oligomers involving As-O-As linkages were found in solution and one tetrameric example (R = 3-NO2-4-OHC6H3) was isolated and structurally characterised. Preliminary ESI-MS studies showed that As(III) species bind to thioredoxin, a possible target for the pharmaceutical activity of Salvarsan and its derivatives.

text: A Reinvestigation of Salvarsan and Related Arsenic Chemistry. In 1910 the first deliberately targeted search for a new chemotherapeutic agent came to fruition when Paul Ehrlich introduced Salvarsan for the treatment of syphilis. This thesis presents a detailed review of the history and literature leading up to and following on from Ehrlich’s discovery and thoroughly investigates the chemistry of Salvarsan and related species. A series of arylarsonic acids was prepared and fully characterised by electrospray mass spectrometry, NMR and X-ray crystallography for six examples. A detailed analysis of the hydrogen bonding in crystals of these molecules showed that they adopt several characteristic motifs which govern the packing in the crystals. Two of the examples containing NH2 groups crystallised as zwitterions while one NH2 containing example containing other bulky groups was is its molecular form. Salvarsan (cyclo 3-amino-4-hydroxyphenylarsenic(I)) was prepared by several different methods and analysed in detail using high resolution electrospray mass spectroscopy. This showed that Salvarsan consists of small cyclic species of the type (RAs)n where R is 3-NH2-4-OHC6H3 and n is three or greater. The dominant species in an aqueous solution of Salvarsan were found to be (RAs)3 and (RAs)5 . A detailed analysis is presented of impurities in Salvarsan prepared by different methods and also in a sample of original commercial Salvarsan. Mixtures of (RAs)n and (R’As)n exchange R groups in aqueous solution at room temperature, as shown by ESI-MS. ESI-MS studies are reported for the oxidation product of Salvarsan, RAs(OH)2 (commercially known as Mapharsen) and related As(III) compounds. Oligomers involving As-O-As linkages were found in solution and one tetrameric example (R = 3-NO2-4-OHC6H3) was isolated and structurally characterised. Preliminary ESI-MS studies showed that As(III) species bind to thioredoxin, a possible target for the pharmaceutical activity of Salvarsan and its derivatives.

year: 2011

title: Development of a Method for Trace Analysis of Dioctyl Sodium Sulfosuccinate by Liquid Chromatography Mass Spectrometry and its Application to Samples from the MV Rena Incident

authors: Bernstein, Daniel Richard

subjects: Liquid chromatography

abstract: The grounding of the MV Rena off the coast of Tauranga, New Zealand in 2011 prompted the application of Corexit® oil spill dispersants in an attempt to mitigate the impact of the spilled oil to coastal ecosystems. A quantitative method was developed employing sonication assisted extraction from beach sand followed by sample clean up by solid phase extraction and analysis by liquid chromatography tandem mass spectrometry for the analysis of Corexit® component dioctyl sodium sulfosuccinate (DOSS) at trace levels. The chromatographic method included the use of a C8 stationary phase with a gradient elution and quantitation by an internal standard approach based on mass spectrometer instrument response. Validation studies gave recoveries of 72 ± 1.7% with an accuracy of 94%. Calibration curves were shown to have a linear range of 0 – 200 μg.L⁻¹. Application of the method to the available environmental samples showed no presence of DOSS.
An attempt was made to apply the instrumental method to heavy fuel oil (HFO) tar-balls and oiled sand samples. Multiple extraction techniques were trialled including liquid-liquid extraction, sonication assisted extraction and anion exchange chromatography with recovery experiments for each method being carried out. Analysis of the extracts showed that quantitative recovery of DOSS had not been achieved for any of the methods investigated.
The difficulties associated with extracting DOSS from HFO tar-balls and oil sands suggest that the application of DOSS to surface oil slicks results in the preferential partitioning of DOSS into HFO. This has implications with respect to the distribution of DOSS in the environment following application, subsequent environmental monitoring and the degradation of HFO components by microbial communities.

text: Development of a Method for Trace Analysis of Dioctyl Sodium Sulfosuccinate by Liquid Chromatography Mass Spectrometry and its Application to Samples from the MV Rena Incident The grounding of the MV Rena off the coast of Tauranga, New Zealand in 2011 prompted the application of Corexit® oil spill dispersants in an attempt to mitigate the impact of the spilled oil to coastal ecosystems. A quantitative method was developed employing sonication assisted extraction from beach sand followed by sample clean up by solid phase extraction and analysis by liquid chromatography tandem mass spectrometry for the analysis of Corexit® component dioctyl sodium sulfosuccinate (DOSS) at trace levels. The chromatographic method included the use of a C8 stationary phase with a gradient elution and quantitation by an internal standard approach based on mass spectrometer instrument response. Validation studies gave recoveries of 72 ± 1.7% with an accuracy of 94%. Calibration curves were shown to have a linear range of 0 – 200 μg.L⁻¹. Application of the method to the available environmental samples showed no presence of DOSS.
An attempt was made to apply the instrumental method to heavy fuel oil (HFO) tar-balls and oiled sand samples. Multiple extraction techniques were trialled including liquid-liquid extraction, sonication assisted extraction and anion exchange chromatography with recovery experiments for each method being carried out. Analysis of the extracts showed that quantitative recovery of DOSS had not been achieved for any of the methods investigated.
The difficulties associated with extracting DOSS from HFO tar-balls and oil sands suggest that the application of DOSS to surface oil slicks results in the preferential partitioning of DOSS into HFO. This has implications with respect to the distribution of DOSS in the environment following application, subsequent environmental monitoring and the degradation of HFO components by microbial communities.

year: 2015

title: Wrestling with Biculturalism in Social Work Education

authors: Glubb-Smith, Kelly J.

subjects: Bicultural social work

abstract: When approached to write a piece on Donna Awatere’s (1984) book Māori Sovereignty from a social work perspective we seized the opportunity to reconsider her work. Revisiting the text after a 30-year-plus hiatus sparked a series of reflective conversations about how we wrestle with teaching biculturalism and our efficacy in preparing students for bicultural practice realities. This article draws upon our co-constructed narratives about what it means to be a social work educator in a bicultural practice landscape. Social work students graduate into an exceedingly complex practice environment fraught with tension about how to resolve inequities across the micro-to-macro continuum. The focus of this article is how Donna Awatere’s work is reflected in the tensions and responsibilities experienced when socialising students into the bicultural mission of social work practice in Aotearoa (New Zealand).

text: Wrestling with Biculturalism in Social Work Education When approached to write a piece on Donna Awatere’s (1984) book Māori Sovereignty from a social work perspective we seized the opportunity to reconsider her work. Revisiting the text after a 30-year-plus hiatus sparked a series of reflective conversations about how we wrestle with teaching biculturalism and our efficacy in preparing students for bicultural practice realities. This article draws upon our co-constructed narratives about what it means to be a social work educator in a bicultural practice landscape. Social work students graduate into an exceedingly complex practice environment fraught with tension about how to resolve inequities across the micro-to-macro continuum. The focus of this article is how Donna Awatere’s work is reflected in the tensions and responsibilities experienced when socialising students into the bicultural mission of social work practice in Aotearoa (New Zealand).

year: 2023-07-27