Automation sample changers

Connect the outlet of the multiposition valve to the microdialysis probe inlet and begin perfusion with aCSF at 2.0 pL/min. Connect the outlet of the probe to the automated sample changer (see Note 4 for connections). 

Set up vials containing 4 pL TCA/homoserine in the automated sample changer Connect the changer to a recirculation cooler that maintains the temperature at 2°C. 

In vitro CuS04-induced plasma oxidation (Schnitzer et al., 1998) was assessed by a Helios b (Spectronic Unicam, Cambridge, UK) spectrophotometer equipped with a 7 position automated sample changer. In quartz cuvettes, 20 pil of plasma were added to 880 pd of phosphate buffer solution, pH 7.4, with 146 mM NaCl at 37 °C for 5 min. The oxidation reaction was started by the addition of 100 pi CUSO4 ImM, and the absorbance of resulting conjugated dienes, at 245 nm, was continuously recorded for 3 h at 37 °C. 

Test G Sample stability. Samples are set into an automated sample changer after preparation and measured one by one. The sample changer holds up to 120 samples with 20 min measuring time (256 scans) it can take up to 40 h before the last sample has been measured. Therefore a check was made to see whether the time between sample preparation and measurement has an influence on the result. The last measurement was made more than 120 h after sample preparation. 

All NMR spectra were measured at Spectral Service GmbH, Cologne, Germany, on an NMR Spectrometer AC-P 300 (Bruker, Karlsruhe, Germany) equipped with automated sample changer and QNP-head for nuclei H, and P. Magnetic flux density is 7.05 T proton... 

NMR spectrometer Bruker 500 or 600 MHz Avance III spectrometer equipped with a 5 mm TCI CryoProbe with an ATM accessory (automatic tuning and matching) and a Sample Jet automated sample changer (Bruker) (reeNote 1). 

Load the NMR samples into a Samplejet Automated Sample Changer. 

Load NMR samples into a Samplejet Automated sample changer and acquire a ID proton NMR at the desired temperature (298 K). Each experiment takes 3 min with 128 scans. 

An automatic probe tuning and matching (ATM) accessory allows one to automatically tune the NMR probe to the desired nuclei s resonant frequency and match the resistance of the probe circuit to 50 Q [7]. Traditional NMR instruments are designed so that one must perform these adjustments manually prior to data acquisition on a new sample. The advent of the ATM accessory allows the sampling of many different NMR samples without the need for human intervention. The ATM in conjunction with a sample changer enables NMR experiments to be conducted under complete automation. The sample changers are designed so that once the samples are prepared, they are placed into the instrument s sample holders. Data are then acquired under software control of both the mechanical sample delivery system as well as the electronics of the spectrometer. 

The titration process has been automated so that batches of samples can be titrated non-manually and the data processed and reported via printouts and screens. One such instrument is the Metrohm 670 titroprocessor. This incorporates a built-in control unit and sample changer so that up to nine samples can be automatically titrated. The 670 titroprocessor offers incremental titrations with variable or constant-volume steps (dynamic or monotonic titration). The measured value transfer in these titrations is either drift controlled (equilibrium titration) or effected after a fixed waiting time pK determinations and fixed end points (e.g. for specified standard procedures) are naturally included. End-point titrations can also be carried out. 

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-... 

In principle there is no label, if not set by the user, to identify the given DISNMR file as an FID or spectrum, or if the NMR data is from a H or C experiment. However the Bruker automation software, primarily developed to connect older type spectrometers (AC, AM) to a sample changer, allows the user to structure the name in such a way that it carries additional information with respect to the type of experiment. The user is referred to the corresponding automation manual available from Bruker and to the name conventions set by the key NMR operator at your site. 

In LC-NMR this problem does not arise in the same way as it does in standard sample changer automation systems, where a change between such different solvents as water and chloroform is possible. In LC-NMR, the samples are eluted from a column in a mixture of solvents, in which only the relative composition changes ... 

Changing solvents also has an effect on the homogeneity of the magnetic field. Again, the observed changes in LC-NMR systems are not as large as those found in normal sample changer automated devices ... 

Some powder diffractometers, particularly those which are used for routine analysis of multiple samples of the same kind, can be equipped with multiple sample changers (usually from 4 to 12 specimens can be accommodated by a single sample changer). This ensures straightforward software control over the data collection process within a series of samples and enables better automation, as data sets from multiple samples may be collected without operator intervention, e.g. overnight or during a weekend. Multiple sample changers are common in powder x-ray diffractometers used... 

X-ray diffraction (XRD) for phase analysis, crystallographic information, residual stress, texture analysis, and reflectometry on powders, bulk, or thin films. Philips X Pert PRO, and a second Philips dual diffractometer system with automated PC control, independent theta/20, sample spinner, and 21 sample changer can be used for crystallography and Rietveld analysis of samples flat, irregular, thin films, or in glass capillaries. 

Potentiometric titrations can be easily automated and controlled by microprocessors or computers. The extent of automation is such that, in the same vessel, multiple titrants may be used sequentially, providing for the determination of several analytes in one sample. Sample changers carrying up to and beyond 60 samples can be attached with ease, vastly decreasing the technician time to produce multiple sample results. 

Automation is one important prerequisite for high-throughput methods. Automated routines are nowadays available from nearly all companies. This equipment also comprises automatic pipeting as well as automatic sample changers. As this is particularly helpful for proteomics studies where-due to the digestion with different proteases a large number of samples is obtained, the clear focus is so far on proteins and no commercial Lipidomics MALDI-based platform is available so far (Wenk 2005). 

Figure 3.32. An automated thermobalance, (a) Balance, furnace, and sample changer mechanism (ft) furnace and sample holder (50). ( ) A. gas flow-meter B. furnace C. sample-holder disk D. cooling fan E, Cahn Model rtl recording balance F. balance platform, (ft) A. gas inlet tube B, thermocouples C. furnace heater windings and insulation D. sample container E. sample-holder disk F. ceramic sample probe.

A schematic diagram of the automated EGD apparatus is shown in Figure 8.31. Basically, the apparatus consists of a sample-changing mechanism and furnace, a programmer to control the rate of furnace temperature change, a thermistor thermal conductivity cell and bridge circuit, a two-channel strip-chart potentiometric recorder, and a helium supply and gas flowmeter. The electronic circuits for the sample changer mechanism were the same as previously described for the automated DTA apparatus (121). 

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