The solubilities of paracetamol and ibuprofen were determined in two different ionic liquids at temperatures of 298.15 K, 308.15 K, 318.15 K, 328.15 K, and 338.15 K. The ionic liquids selected were 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 ] and 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM] [PF 6 ]. In addition, solubility data for paracetamol and ibuprofen in water are reported at the same temperatures extending the data commonly reported in pharmaceutical reference texts. For all solvents the concentration of drug in solution was determined by UV spectrophotometry.
his paper describes results from an experimental investigation into the scale-up of oscillatory flow mixing (OFM) in geometrically scaled baffled tubes ranging from 24 mm to 150 mm diameter and from 1 m to 4.5 m in length. Measured axial dispersion coefficients are reported together with case studies and an empirical correlation. An alternative multi-orifice reactor geometry with the potential for use in large-scale plant was also constructed and tested from which it was concluded that OFM is a technology which lends itself readily to scaling-up from laboratory to pilot plant scale, and to industrial scale. Experiments performed on small laboratory OFM apparatus containing less than one litre of fluid can with confidence be used to predict mixing behaviour in much larger plant containing hundreds of litres of fluid.
SynopsisFour different types of ir experiments, involving changes in pH, changes i n pressure, and the use of nonaqueous solvents, and with either albumin molecules dissolved in saline or adsorbed albumin films, support the hypothesis that the bandwidth of the amide I vibration of albumin is directly related to the amount of bound water in this protein. From the amide I band narrowing and the amide I shift to higher frequencies, it is proposed that a more ordered helix structure results as the amount of bound water is decreased.
The crystallisation of Active Pharmaceutical Ingredients (API) from conventional organic solvents can yield undesirable crystal habits with poor physical properties that cause downstream processing problems. It has been proposed that ionic liquids (ILs) may offer an opportunity to perform controlled crystallisations from this media. Using paracetamol and the ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF 6 ] and 1-hexyl-3-methylimidazolium hexafluorophosphate [hmim] [PF 6 ] fundamental understanding of these systems was established by determining the Meta-stable Zone Width (MSZW) before completing a series of cooling crystallisations investigated across a temperature range between 20°C and 90°C. It has been shown that paracetamol can be crystallised from these systems to obtain the stable monoclinic form I and that the particle habit and size can be manipulated by changing the IL used, the solution concentration and the mechanism of crystal growth and in some cases crystal habits not commonly found from aqueous or organic solvents were produced. The results demonstrate that ILs may be a viable approach to manipulate crystal properties and should be explored more widely as a potential media for crystallisation of API.
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