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Item type:Publication, Chemometrics-assisted cross injection analysis for simultaneous determination of phosphate and silicate(2016-07-14); Tiyapongpattana, WarawutThis work presents a novel method for simultaneous spectrophotometric determination of phosphate and silicate by using a cross injection analysis (CIA) coupled with the use of partial least squares (PLS) for data evaluation. The detection principle is based on the well-known ‘molybdenum blue’ method. The molybdate ions in the presence of stannous chloride in acidic medium give phosphomolybdenum blue and silicomolybdenum blue as products. In this work, all the liquids, including sample and reagents were simultaneously introduced into a CIA platform by using two peristaltic pumps for controlling the x-channel and y-channel flow which was automatically manipulated by using in-house control board. Crossflow provides sufficient mixing inside the platform prior detection of the absorption spectra of blue complexes in the wavelength of 400–900 nm. Since spectra of the blue colour product of phosphate and silicate are resemblant, these two analytes therefore reciprocally interfere with one another. This results in difficulty in simultaneous analysis of phosphate and silicate. In this work, PLS was utilised as assistor of CIA system for simultaneous analysis of phosphate and silicate using molybdenum blue reaction without using any modification of reagents and addition of selective masking agent. The calibration ranges are 0.1–6 mgP L<sup>−1</sup> and 5–100 mgSi L<sup>−1</sup> for phosphate and silicate, respectively. By using CIA coupled with PLS for data evaluation, the analysis of two analytes was achieved within 1.5 min with only single injection. The developed system was applied to natural water samples and the system was validated with the conventional methods. By statistical paired t-test, there was no evidence of significant difference at 95% confidence level (t<inf>stat</inf> = 2.28, t<inf>critical</inf> = 2.31 and t<inf>stat</inf> = 0.62, t<inf>critical</inf> = 2.31 for phosphate and silicate, respectively). This implied that the chemometrics-assisted CIA system was successfully developed for simultaneous spectrophotometric determination of phosphate and silicate.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effect of media and salinity on lipid content of cyanobacterium Hapalosiphon sp(2014-01-01)The aim of the present work was to study the individual effect of media constituents: sodium nitrate, di-potassium hydrogen orthophosphate, ferric ammonium citrate and salinity on lipid production by Hapalosiphon sp. which cultured in BG-11 medium, in view of its possible utilization as novel raw materials for biodiesel production. Lipid content of Hapalosiphon sp. cultivated in medium containing 1, 500 mg/L sodium nitrate was 15. 78±0. 51%. Indeed, the highest lipid yield of 0. 063 g/L was found in a medium containing 375 mg/L sodium nitrate. The highest lipid content of Hapalosiphon sp. cultivated in medium containing 10 mg/L di-potassium hydrogen orthophosphate was 11. 50±0. 45%, while the highest lipid yield of 0. 044 g/L were occurred in a medium containing 20 mg/L di-potassium hydrogen orthophosphate. In various ferric ammonium citrate concentrations cultivation, the highest lipid content of Hapalosiphon sp. cultivated in a medium containing 9 mg/L ferric ammonium citrate was 12. 64±0. 38%. However, the highest lipid yield of 0. 063 g/L occurred in a medium containing 12 mg/L ferric ammonium citrate. The significantly highest lipid content and lipid productivity of Hapalosiphon sp. cultivated in salinity 10 ppt were 9. 95±0. 34% and 0. 049 g/L respectively.3