Vial monitoring

A number of methods are used to determine the electroosmotic flow velocity [80-84]. These include measuring the change in level or increase in mass of the receiving vial, monitoring the movement of a dye molecule in a capillary downstream of the detector, and on-line photometric detection of a neutral marker (such as mesityl oxide, formamide, acetone, thiourea, dimethyl sulfoxide, methanol, etc). The neutral marker method is straightforward and involves injection of a dilute solution of the marker compound in the separation buffer or water either separately or together with sample. 

In 2003, the microwave-assisted coupUng of aryl hahdes with acetylenes using a palladium catalyst were carried out employing a modified Smith Process vial [49]. These vessels, equipped with a polypropylene frit and screw cap at the bottom, and sealed with an aluminum crimp cap fitted with a silicon septum at the top (Fig. 8), faciUtated the processing of approximately 1 g of solid support. Notably, they are compatible with stirring of the reaction mixture and monitoring of the temperature and pressure. 

The checkers found considerable variation in the rate of the reaction in different runs, the time required for its completion ranging from 3 to 10 hours. It is therefore advisable to monitor the progress of the reaction. For this purpose small aliquots (ca. 0.05 ml.) were withdrawn from the flask with a syringe and hydrolyzed by injection into a vial containing ether and saturated ammonium chloride. The relative amoimts of enol silane and cyclopropoxy sdane were determined by gas chromatography on an 0.6 cm. X 3.7 m. column of 3% OV-17 coated on 100-120 mesh Chromosorb W. With a column temperature of 120° and a carrier gas flow rate of 20 ml. per minute, the retention times for the enol silane and the cyclopropoxy silane are ca. 1.9 and 2.3 minutes, respectively. 

Most of the reference substances/preparations are stored in cold rooms controlled at between 2°C and 8°C. However, a number of substances/preparations which are relatively unstable are stored at -20°C or, in a few cases, e.g. vaccines, at -8o°C. The reference substances/preparations may be stored for years under these conditions and their fitness for use is continually monitored as described above. Thus, the status of each reference substance/preparation is indicated in the catalogue. It is recommended that purchasers only order a sufficient amount for immediate use since the stability of the contents of opened vials or ampoules cannot be guaranteed. 

Water samples, received from the respective groundwater trials, are analyzed by direct aqueous injection (DAI) by LC/ESI-MS/MS. A 1-mL volume of the water is pipetted into a 1.8-mL autosampler vial. The internal standard solution is added (200 qL) and mixed. The vials are capped and analyzed by LC/ESI-MS/MS using the selected reaction monitoring (SRM) mode. 

For accurate temperature monitoring when conducting a temperature-controlled program, a minimum filling volume of the vessels is crucial. In the case of IR temperature measurement from the bottom of a vessel, only a very small amount of reaction mixture (ca. 50 pL) is sufficient to obtain a precise temperature feedback in a monomode instrument (CEM Discover series). On the other hand, a rectangular mounted IR sensor, as used in Biotage instruments (see Section 3.5) requires a certain minimum filling volume (200 pL for the smallest reaction vials see Fig. 3.21). 

Fig. 1.23. Monitor AW 2. In the foreground right Sample vial with measuring electrodes and resistance thermometer, behind to the left the control- and analysis unit. The storage of LN2 and its control valve are not shown. The resistance in the measuring head has to be large compared with the resistance to measure e. g. 1011 1 (photograph AMSCO Finn-Aqua, D-50354 Hiirth).

If the loading of vials has to be done on cold shelves, a smaller loading door as shown in Fig. 2.50 and 2.51.1 should be built in to reduce the amount of air diffusing into the chamber. In addition, a small overpressure of sterile air or N2 in the chamber reduces the condensation of ice. If N2 is used, the 02 content near the loading door should be monitored. 

The simplest CEC equipment must include the following components a high-voltage power supply, solvent and sample vials at the inlet and a vial to collect waste at the outlet of the capillary column, a column that simultaneously generates EOF and separates the analytes, and a detector that monitors the component peaks as they leave the column. Figure 4 shows a scheme of an instrument that... 

The detection limits of the antibody-sandwich bioprobe was monitored by immersing the probe into vials containing variable antigen concentrations ranging from 10 to 100 ng/ml as shown in Figure 7.16. 

The biotransformation was monitored by analysing samples taken periodically by HPLC. Samples (450 pL) were withdrawn from the biotransformation medium, acidified with 1 M HCL (50 pi) to stop the reaction and stored on ice for 30 min. All samples were centrifuged at 23 000g for 10 min at 4 °C to remove the cell debris and the supernatant filtered into HPLC vials using nylon filters (0.2 pm). 

Fig. 1.4 Planetary miU vial with antenna mounted on cover equipped with temperature and pressure sensors for GTP wireless monitoring gas conditions during milling...

The sample rack is unique in that it possesses pitch both front to back and side to side. A single robot pick-up point is defined, and an optical (IR) sensor constantly monitors the pick-up point for the presence of a sample. Vials placed in the rack roll down to the pickup point, under the influence of gravity. The rack allows implementation of a novel processing scheme. 

---