Instrument optimisation

Natural ingredients based lipstick formulations have been prepared. The effects of the natural waxes, oils and solvent compositions on the viscosity and melting point of the lipstick have been studied. The result indicates that the viscosity and melting point of the lipstick can be manipulated by changing the composition of natural candelilla wax, camauba wax and beeswax in the formulation. Another important lipstick characteristic, which is hardness, will be studied. Consumer acceptance towards the product will be investigated. Finally, by relating the consumer data and instrumentation analysis, optimisation process will be conducted. 

Following previous works on physico-chemical characterisation of sunflower low-methoxyl pectins (Alarc o-Silva, 1990, Leitao at al., 1995) and technological utilisation in the manufacture of low calorie gels (Alarc o-Silva et al., 1992), this investigation was carried out to test the suitability of that pectin to the confection of grape juice reduced calorie jellies in comparison with two types of commercial pectin. Aiming at the optimisation of low-calorie jelly formula, based on consumers preferences, the jellies were submitted to a sensory panel test judgement and instrumental texture-analysis. 

Published evidence highlights the efficacy of SFE. However, the method is highly matrix and analyte dependent and must be optimised for each combination of material and analyte. Interaction between analyte and matrix is often difficult to predict and optimisation of the extraction procedure is not simple. Understanding of the processes that occur during SFE has lagged behind instrumental developments. The results obtained from SFE are highly dependent on the operational parameters used during the extraction (Table 3.19). 

A real breakthrough of analytical SFE for in-polymer analysis is still uncertain. The expectations and needs of industrial researchers and routine laboratories have not been fulfilled. SFE presents some severe drawbacks (optimisation, quantification, coupling, and constraints as to polarity of the extractable analytes), which cannot easily be overcome by instrumental breakthroughs but... 

In the mid-to-late 1990s, SFC became an established technique, although only holding a niche position in the analytical laboratory. The lack of robust instruments and the inflexibility of such systems has led to the gradual decline of SFE-SFC. Only a small group of industrial SFE-SFC practitioners is still active. Also the application area for SFC is not as clearly defined as for GC or HPLC. Nevertheless, polymer additives represent a group of compounds which has met most success in SFE-SFC. The major drawbacks of SFE-SFC are the need for an optimisation procedure for analyte recovery by SFE (Section 3.4.2), and the fair chance of incompatibility with the requirements of the chromatographic column. The mutual interference of SFE and SFC denotes non-ideal hyphenation. 

Satisfactory performance of the SFE-SFC-HRMS instrumentation (resolution 1200) was only possible after optimisation (temperatures, restrictor and quartz tube positions, flow characteristics and sample transfer conditions). Mass spectra obtained for Irganox 1010/1076/1330 and Irgafos 168/P-EPQ by SFC-HRMS were identical with those obtained by use of DIP [431]. However, the sensitivity of the SFE-SFC-MS interface is low (at best 4 % of that obtained with sample introduction via DIP). An enormous amount of sample is lost in all parts of the coupling system (SFE, SFC and... 

LC-PB-MS is especially suited to NPLC systems. RPLC-PB-MS is limited to low-MW (<500 Da) additives. For higher masses, LC-API-MS (combined with tandem MS and the development of a specific mass library) is necessary. Coupling of LC via the particle-beam interface to QMS, QITMS and magnetic-sector instruments has been reported. In spite of the compatibility of PB-MS with conventional-size LC, microbore column (i.d. 1-2 mm) LC-PB-MS has also been developed. A well-optimised PB interface can provide a detection limit in the ng range for a full scan mode, and may be improved to pg for SIM analyses. 

To overcome those deficits of existing instruments, the MOREHyS (Model for Optimisation of Regional Hydrogen Supply) model was developed as a novel tool to assess the introduction of hydrogen as a vehicle fuel by means of an energy-system analysis.2 In the next section, the main features of the MOREHyS model are described. 

The performance of atmospheric pressure interfaces appears to vary widely from instrument to instrument. A variety of interface designs are available from the various manufacturers. Optimisation of operating parameters, such as cone voltage, temperature, and mobile-phase composition is always necessary prior to actual analysis of samples. A given optimised set of parameters is likely to change with changing matrices, and may also vary with local conditions, such as the alkaline metal content of water or tubing used. 

Specificity may be achieved through sample preparation, chromatographic selectivity, the selectivity of the detection method or combinations of these. It is often tempting to utilise the most selective detection method available (such as MS or MS/MS), since this can reduce the effort required in optimising the sample preparation and chromatography. However, whilst this is often the most expedient approach in early development, it may not always be suitable to transfer expensive, highly technical methods and instrumentation into a manufacturing environment if this is required. 

Capillary electrophoresis (CE) is the most rapidly expanding separation technique in pharmaceutical analysis and is a rival to HPLC in its general applicability. The instrumentation is quite straightforward, apart from the high voltages required, but the parameters involved in optimising the technique to produce separation are more complex than those involved in HPLC. The technique is preferred to HPLC where highly. selective separation is required. 

A systematical approach of sample preparation methods and optimisation of the quality aspects of sample preparation may enhance the efficiency of total analytical methods. This approach may also enhance the quality and knowledge of the methods developed, which actually enhances the quality of individual sample analyses. Unfortunately, in bioanalysis, systematical optimisation of sample preparation procedures is not common practice. Attention to systematical optimisation of assay methods has always been mainly on instrumental analyses problems, such as minimising detection limits and maximising resolution in HPLC. Optimisation of sample extraction has often been performed intuitively by trial and error. Only a few publications deal with systematical optimisation of liquid-liquid extraction of drugs from biological fluids [3,4,5]. 

Cerrato Oliveros, C. Boggia, R., Casale, M., Armanino, C., Forina, M. (2005) Optimisation of a new headspace mass spectrometry instrument discrimination of different geographical origin olive oils. J. Chromatogr. A 1076 7-15. 

For a given ICP-OES instrument, the intensity of an analyte line is a complex function of several factors. Some adjustable parameters that affect the ICP source are the radiofrequency power coupled into the plasma (usually about 1 kW), the gas flow rates, the observation height in the lateral-viewing mode and the solution uptake rate of the nebuliser. Many of these factors interact in a complex fashion and their combined effects are different for dissimilar spectral lines. The selection of an appropriate combination of these factors is of critical importance in ICP-OES. This issue will be addressed in Chapter 2, where experimental designs and optimisation procedures will be discussed. Many examples related to ICP and other atomic spectrometric techniques will be presented. 

A screening design detected significant instrumental and chemical variables to volatilise and measure Sb. They were optimised using response surfaces derived from central composite designs. Findings were confirmed using artificial neural networks... 

On the other hand, the huge efforts made by atomic spectroscopists to resolve interferences and optimise the instrumental measurement devices to increase accuracy and precision led to a point where many of the difficulties that have to be solved nowadays cannot be described by simple univariate, linear regression methods (Chapter 1 gives an extensive review of some typical problems shown by several atomic techniques). Sometimes such problems cannot even be addressed by multivariate regression methods based on linear relationships, as is the case for the regression methods described in the previous two chapters. 

ICP-OES Five instrumental ICP variables were optimised via a full... 

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