Automation of sampling

As stated In Chapter 1, the first few stages of the analytical process are also the more complex and the source of potential major errors, and the concept of a sample is rather extensive. 

The automation of preliminary operations in the analytical process Is rendered particularly difficult by (a) the large variety of existing samples, available in all three states of aggregation (solid, liquid and gas) and In different particle sizes, (b) the diversity of circumstances (sampling location and distance to the laboratory, need for preservation) and (c) the pretreatment required (dissolution, preconcentration, interference removal, etc.). All this makes the first stage of the analytical process one that cannot be automated In every case In fact, endeavours In this field are often aimed at a particular type of sample or application (e.g. clinical, food, agricultural or pharmaceutical analysis). 

Preliminary operations usually consist of a number of steps, all of which can in principle be carried out without human Intervention. For simplicity, the target of automation can be sampling, sample treatment or both sub-stages. The last situation Is by far the commonest, even though the complete automation of the entire sampling stage is difficult. 

Automatic sampling and treatment systems (ASP or automated sample preparation according to Burns [1]) can be incorporated Into the analytical process in one of three fashions, namely  

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On-line automation of sample preparation and chromatographic analysis steps... 

Typical protein precipitation procedures use one volume of plasma plus three to six volumes of acetonitrile or methanol (or a mixture) with the internal standard at an appropriate concentration for the assay. Poison et al.102 reported that protein precipitation using acetonitrile eliminates at least 95% of the proteins after filtration or centrifugation, the supernatant can often be directly injected into the HPLC/MS/MS system. Usually this step is performed using 96-well plates that are ideal for semi-automation of sample preparation. Briem et al.103 reported on a robotic sample preparation system for plasma based on a protein precipitation step and a robotic liquid handling system that increased throughput by a factor of four compared to a manual system. 

The automation of sample preparation is clearly a requirement if one wants to measure a reasonably high number of test compounds. While sample changers have been used for a long time in analytical NMR laboratories, sample preparation robots have been introduced only recently, especially in the field of biomolecular NMR. They offer the great advantage that the samples are freshly prepared under identical conditions and delivered to the NMR instrument in a just-in-time fashion. Thus, they circumvent the disadvan-... 

For further information on sampling and automation of sampling, including a discussion of apparatus suitability test acceptance criteria for IR or MR dosage forms, please refer to Chapters 2, 3, and 13. 

Wells, D. A. and Lloyd, T. L., Automation of Sample Preparation for Pharmaceutical and Clinical Analysis, In Sampling and Sample Preparation for Field and Laboratory Fundamentals and New Directions in Sample Preparation, Pawliszyn, J., Ed., Vol. XXXVII, Elsevier Science, Amsterdam, Netherlands, pp. 837—868, 2002. 

Automation of sample preparation of foodstuffs for trace metal analysis 123... 

AUTOMATION OF SAMPLE PREPARATION OF FOODSTUFFS FOR TRACE METAL ANALYSIS... 

Guillen, D.A., Barroso, C.G., and Perez-Bustamante, J.A., Automation of sample preparation as a preliminary stage in the high-performance liquid chromatographic determination of polyphenolic compounds in sherry wines, J. Chromatogr. A, 730, 39, 1996. 

The automation of sample handling has not taken off as some predicted in the nineteen sixties when the first automatic systems were developed for tensile machines and hardness and density apparatus. Robots are rare alongside the test rig and the reason is doubtless to do with volume, as such... 

Laboratory robotics represents an attractive approach for the automation of sample preparation and separation steps in radiochemical analysis, and for many years, such methods have been routinely used by laboratories serving the analytical needs of the International Atomic Energy Association.64 68-72 However, there are currently a limited number of published studies containing technical details on the radiochemical separations and how they were automated. Accordingly, the remainder of this chapter will focus on fluidic approaches. 

Luque de Castro, M.D., Luque Garcia, J.L. Automation of sample preparation. In Mester, Z., Sturgeon, R. (eds.) Sample Preparation for Trace Element Analysis, pp. 649-680. Elsevier, Amsterdam (2003)... 

Using a highly localised analysis requires a sample displacement system, similar to that used in electron microscopy, and makes the automation of sample changing difficult. 

As more and more samples are sent for analysis, automated procedures will be required. Improvements in instrumentation and software will facilitate the development of greater automation of sample preparation into a fully integrated analytical method. 

Finally, no discussion of this topic would be complete without the mention of automation in sample preparation and its impact on this activity. Laboratory robotics initial focus was on the automation of sample preparation and is used in that way in many laboratories, but islands of automation have developed within certain organizations where certain portions of sample preparation such as SPE are automated. 

Pioneer work in thin-layer chromatography to isolate and analyze medicinal compounds was performed by Izmailov and Shraiber on unbound alumina as early as 1938.12 However, E. Stahl introduced the term thin-layer chromatography in 1956, which was considered the beginning of modern TLC.13 Since the 1960s, commercialization of precoated TLC plates and automation of sample application and detection have made it accessible to all laboratories. A number of valuable texts have been written about the history of TLC.14-20 The most recent one is reviewed by C. F. Poole.12... 

High-throughput productivity requires automation of sample preparation. 

One area where LIMSs have not provided out-of-the-box support is in the automation of sample preparation. This may be due to the fact, that analytical labs do not have sample-preparation workstations or that there is no standard for these workstations. Nevertheless, the authors think that sample preparation can be automated, providing similar benehts as in high throughput screening, for example. The use of portable devices such as pocket has been reported in the laboratory [74]. Commercially available applicahons such as LimsLink (Labtronics, Inc.) can upload laboratory instrument data from handheld devices to any LIMS. 

Automation of sample preparation of pharmaceutical solids has been quite successful. A variety of instrumentation is commercially available from several vendors. The instruments are capable of handling a dosage form, placing it into a vessel, adding solvent, and mechanically homogenizing the sample until the analyte is dissolved. Typically, the instrument can then dilute to the desired concentration. Some models are also capable of transferring the prepared solution to a HPLC injector or an ultraviolet spectrophotometer for measurement. These instruments use accurate balances to control the accuracy of solvent additions and dilutions. 

Another development in HPLC analysis is the interfacing of on-line sample clean-up technologies at the front end of the HPLC analytical column. Using a switching valve, complex samples can be injected directly onto a sample preparation column, the stationary phase of which is designed to bind the analyte(s) of interest to the exclusion of the rest of the matrix, which runs to waste. Then the valve is switched and the mobile phase flows through the sample preparation column where it picks up the analyte(s) and carries them onto the analytical column and through to the detector in the normal way. This automation of sample preparation saves time and effort and reduces errors. There are many applications of HPLC assays in conjunction with on-line sample clean-up methods in the literature ... 

Indeed since the 1980s tremendous changes have occurred the most striking changes are miniaturization and automation of sample procedures and analytical techniques. 

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