Sample preparation serial

The configuration can be expanded by adding other sample preparation instruments to facilitate automating other preparative steps that may intervene between SFE and the analytical instrument, e.g. solvent exchange, internal standard addition, serial dilutions for calibration curve generation, SPE for further cleanup of the extract output by SFE, derivatisation of components within the SFE extract, and many other (currently) manual-human intervention techniques. 

The sample preparation step in Figure 3.9 in the simplest case would include only the aspiration, but often steps like dilution, pre-concentration, and other treatments will be performed before injection of the sample onto the separation column. This is easily performed on modem instruments that allow injector programming and the use of additional valves. This will be discussed further in the next section about parallelizing steps. If parallelizing is not possible and a purely serial analysis is required, the required treatment should be abandoned or performed off-line. 

A student obtains 100.0 mL of 0.100 M HC1. The student prepares serial dilutions of the acid to obtain solutions of the following concentrations 0.0500 M, 0.0100 M, 0.00500 M and 0.00100 M. The student determines the pH of each of the solutions with a pH meter and then from an assortment of indicators available and using Appendix B, adds the appropriate indicator to samples of the solutions produced. 

In order to determine chemical elements in soil, samples of the soil must undergo a solid-liquid extraction. Sometimes the extracts resulting from this procedure have analyte concentrations that are too high to be measured accurately by the chosen method. Therefore, they must be diluted. At the Natural Resources Conservation Service (NRCS) Soil Survey Laboratory in Lincoln, Nebraska, an automated diluting device is used. Using this device, the analyst accurately transfers aliquots of the extract and a certain volume of extraction solution to the same container. This dilutor may also be used to pipet standards and prepare serial dilutions. 

Calibration standards Prepare serial dilutions of stock standards in 1 mmol/1 HC1 to give concentrations of 0, 25, 50, 100, 250 and 500 nmol/1, and in the case of samples with very high levels also 1000 nmol/1. 

Avoidance of errors in sample preparation (extraction, derivatization) could be minimized by rigorous training of laboratory personnel, including appreciation of the patient behind each anonymous test tube. An environment free of noise and distractions is required to minimize the risk of serial solvent extractions being pooled in the wrong tube redundant labeling of glassware and step-by-step checklists are also critical elements of error prevention and detection. 

The sample preparation procedures for the direct analysis of small molecules in tissue have been described by several papers [120-124], Tissues (brain, heart, lung, kidney, liver, etc.), were immediately frozen and stored at -80 °C after harvest. The frozen tissues were subsequently cut into serial 10-20 pm thick section which was typically prepared by cryosectioning on a microtome at a temperature of -20 °C. The adjacent sections were gently mounted onto a conductive surface, MALDI imaging target plate or glass slides. These plates were desiccated under low vacuum for a short period of time until dry, then robotically or manually coated with the... 

BATCH VERSUS SERIAL APPROACHES TO AUTOMATED SAMPLE PREPARATION... 

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. 

HRGC/PID/FID and GC/PI-IMS are methods that have been used to measure the volatile aromatic components of gasoline in soil (Eiceman et al. 1987 Roe et al. 1989). Sample preparation is simple because the static headspace method is used. The use of serial detectors (PID/FID) with HRGC enhanced selectivity. No recovery data or detection limits were reported for HRGC/PID/FID however, precision was good (2-8% RSD) (Roe et al. 1989). PID has a high selectivity to aromatic hydrocarbons (Eiceman et al. 1987). The combination of PI with IMS (PI-IMS) provided a second basis for resolution of chemical information and thus enhanced selectivity (Eiceman et al. 1987). Reproducibility for the GC/PI-IMS method ranged from 10 to 60% with a detection limit of 18 mg/kg (Eiceman et al. 1987). 

Because of the serial nature of LC-MS, much of the current discussion has centered on ways to reduce LC-MS/MS cycle time. Often the rate-limiting step for drug-discovery bioanalysis lies in the speed with which methods (sample preparation and chromatography) can be prepared for NCEs. One of the frequently overlooked steps is the need to tune and optimize MS/MS transitions for the various analytes studied. Fortunately, most MS vendors now offer semi- or fully automated procedures to perform this task. The origin for these procedures can be traced to the seminal work of Whalen et al., who published an automated procedure known as AUTOSCAN [106]. Itis possible to establish experimental conditions with this procedure in the flow-injection analysis (FIA) mode for 96 analytes in less than one hour. 

Another example of a direct method is the on-line SPE approach embodied by a novel commercial device known as the SPE Card . This apparatus, originally developed by Olech and co-workers, couples 96-well disk SPE in a format that allows direct, serial elution into the mass spectrometer [109], Note that this method should not be confused with the Prospekt system described earlier for on-line SPE. Sample preparation occurs off-Une with the SPE-Card, and the card is placed in an on-Une device that performs serial elution into the MS. This method is considered direct, since it avoids the use of LC columns and removes the various sample transfer steps that normally follow SPE. 

Near the end of incubation, prepare serial dilutions of phosphate standard from the ColorLock reagent kit, in water. Dispense 6 pi of each concentration (100, 50, 25, 12.5, 6.25, 3.13, 1.56, 0 pM) in quadruplicate into the 1,536-well assay plate holding the assay mixture under incubation. For 0 pM prepare 16-32 replicate wells for sufficient sample size in subsequent data analysis. 

Instrument control, sample preparation, and sample injection into the AAS are performed by two MS Windows applications. The first, called MS, provides the user with a "Control Panel" (Figure 7) that will allow complete control of the MS operating parameters. Using a mouse, the user simply clicks the appropriate control button on the screen and the application (through a RS-232 serial line) sends the MS the command. Instrument settings are saved on disk for future use. 

Prepare serial dilution of input phage sample (50 pL aliquot was saved for titering) ... 

A minimum volume of 30 pi of lysate is required for printing microarrays in a dilution format from a 384-well microtiter plate. Fifteen microliter of neat sample is used to prepare serial 1 2 dilutions of the lysate. An additional 15 pi of lysate is required for the neat sample. 

Analytical sample Any solution or media introduced into an instrument on which an analysis is performed, excluding instrument calibration, initial calibration verification, initial calibration blank, continuing calibration blank. The following are all analytical samples undiluted and diluted samples, predigestion spike samples, duplicate samples, serial dilution samples, analytical spike samples, postdigestion spike samples, interference check samples, laboratory control samples, preparation or method blank, and linear range analysis samples. 

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