Sample transfer, automated

Arce et al. [39] developed a flow injection analysis (F1A) system (Fig. 5.3) for online filtration of water samples prior to CE analysis. They also constructed a pump-driven unit for extraction and filtration of soil samples combined with CE in an online mode (automated sample transfer between pre-CE sample preparation step and the CE) [40]. The method was precise and four times faster than conventional methods of sample preparation with an off-line unit. Blood samples are centrifuged immediately to remove red blood cells and the serum is stored as discussed above. Sometimes, urine samples also contain precipitates which are removed by centrifuge. 

In 2D chromatography separations, an aliquot from a first column (method) is transferred into the next separation method in a sequential and repetitive manner using automated sample transfer valves which are equipped with one or more sample loops. Alternatively, as a simpler and not quite as useful transfer technique, heart cuts from peaks in the first separation... 

S. S. Ismail A New Automated Sample Transfer System for Instrumental Neutron Activation Analysis , Journal of Automated Methods and Management in Chemistry, Volume 2010 (2010), Article ID 389374, 8 pages... 

Sample preparation, injection, calibration, and data collection, must be automated for process analysis. Methods used for flow injection analysis (FLA) are also useful for reliable sampling for process LC systems.1 Dynamic dilution is a technique that is used extensively in FIA.13 In this technique, sample from a loop or slot of a valve is diluted as it is transferred to a HPLC injection valve for analysis. As the diluted sample plug passes through the HPLC valve it is switched and the sample is injected onto the HPLC column for separation. The sample transfer time typically is determined with a refractive index detector and valve switching, which can be controlled by an integrator or computer. The transfer time is very reproducible. Calibration is typically done by external standardization using normalization by response factor. Internal standardization has also been used. To detect upsets or for process optimization, absolute numbers are not always needed. An alternative to... 

These authors reported greatly improved sample transfer without pipette failure due to plugging caused by thrombin clot formation when a LEAP HTS PAL autosampler was used for liquid transfer automation. 

The advantages of this screen filter, as cited by the authors, consist of its reusability, its standard 96-well format size, and its ability to be used whenever sample transfer or pipetting is needed. After usage, the screen filter can be easily cleaned by rinsing with water and methanol and additionally, by ultrasonication in water or methanol or other appropriate solution. The filter can be inserted into a plasma storage plate before sample transfer by the Tomtec Quadra used by the authors for automation. 

When creating an automated sample preparation to mimic or reproduce a manual sample preparation procedure, it is wise to break down each step of the procedure and understand its relevance. When transferring the manual steps to automated steps, not every step must or can be transferred individually. For example, when developing a method there might be volume restrictions due... 

S. M. Han and A. Munro, Transfer from manual to automated sample preparation a case study, J. Pharm. Biomed. Anal., 20, 785, 1999. 

Pure HDF injection can be achieved for sample introduction by using vacuum suction. The sample was sucked through an inserted capillary into a short section of microchannels between three ports. Different amounts could be selected by filling different sections of the microchip [813]. Pressure injection of a DNA sample was also achieved via a transfer capillary sequentially to a five-channel microchip. The use of one capillary allowed for automated sampling necessary for continuous monitoring of an enzymatic DNA restriction digestion experiment [320],... 

The majority of the applications of 14 MeV neutron activation analysis involve the use of short-lived indicator radionuclides. Therefore, it is essential that the sample be returned quickly to the counting station following irradiation. Pneumatic sample transfer systems employing compressed nitrogen, or a vacuum are most commonly used 34-35>. An inexpensive system may be constructed from ordinary low density polyethylene tubing 18>. Irradiation, delay and counting times are ordinarily controlled by means of preset timing circuits. Completely automated control and transfer systems are available commercially. 

The plate-to-plate tube transfer at -20 °C in the Liquid Master Store and in the Smart Compound Depository are similar robotic operations that can be combined in one automated sample bank. The combination of 96-tube and 384-microtube plate-to-plate tube transfer in one system might be the preferred solution for sample management of small- and medium-sized HTS libraries. 

Automated sample preparation can be accomplished by using a batch or a serial approach. In the batch mode, multiple samples are prepared and then transferred to the analytical instrument for measurement. In the serial mode, samples are prepared one at a time and the SP device is connected (integrated) with the analytical instrument only. 

Automated sample preparation suitable for the assays starting with solid or oily material is rather complicated and causes problems. This highly labour intensive procedure caused problems when it was done manally due to the nature of the material to be handled. Thus, only certain percentages of the compounds delivered in solid form can be handled by robotics. For this procedure in screening companies, only a low rate of automation is observable so far. Nevertheless, first automated filling stations exist in which a defined amount of a powder can be transferred from standardized vessels to test tubes for subsequent dilution. 

Due to the intended use of late-phase methods, the methods should be optimized to be as rapid and simple as possible while meeting the specified requirements. Considerations in method development should include the ability to fully automate sample preparation and to ensure that the methods are sufficiently rugged and robust to allow for transfer to other laboratories. 

A limitation to liquid-liquid extractions is that they are very difficult to automate. However, two approaches have been reported. Hsieh et al. reported the automated liquid-liquid extraction of hydrochlorothiazide from plasma and urine that simply mimics the actions of the analytical chemist (28). They made use of a robotic system that was programmed to combine the sample, internal standard solution, buffer, and solvent. The robot then mixed the sample, transferred the extract to a new tube, evaporated the extract, and injected it onto an HPLC. 

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