Fraction collector, automatic

The conditions for gas chromatography are given in Note 9. The product was found mainly in fractions 2-20 by the submitters. The first 25-ml. fraction contained considerable amounts of byproducts, while fractions 21 and higher contained 1-adamantanol. The checkers collected 10-ml. fractions with an automatic fraction collector. 

The core - flood apparatus is illustrated in Figure 1. The system consists of two positive displacement pumps with their respective metering controls which are connected through 1/8 inch stainless steel tubing to a cross joint and subsequently to the inlet end of a coreholder 35 cm. long and 4 cm. in diameter. Online filters of 7 im size were used to filter the polymer and brine solutions. A bypass line was used to inject a slug of surfactant solution. Two Validyne pressure transducers with appropriate capacity diaphragms are connected to the system. One of these measured differential pressure between the two pressure taps located about one centimeter from either end of the coreholder, and the other recorded the total pressure drop across the core and was directly connected to the inlet line. A two - channel linear strip chart recorder provided a continuous trace of the pressures. An automatic fraction collector was used to collect the effluent fluids. 

He et al. (2002) used an off-line HPLC/CE method to map cancer cell extracts. Frozen ovarian cancer cells (containing 107 cells) were reconstituted in 300 pL of deionized water and placed in an ultrasonic bath to lyse the cells. Then the suspension was centrifuged and the solubilized proteins were collected for HPLC fractionation. The HPLC separation was carried out on an instrument equipped with a RP C-4 column, 250 mm x 4.6 mm, packed with 5-pm spherical silica particles. Extracted proteins were dissolved in 300 pL of DI water, and lOOpL was injected onto the column at a flow rate of 1 mL/min. Buffer A was 0.1% TEA in water and buffer B was 0.1% TFA in acetonitrile. A two-step gradient, 15-30% B in 15 min followed by 30-70% B in 105 min, was used. The column effluent was sampled every minute into a 96-well microtiter plate with the aid of an automatic fraction collector. After collection, the fractions were dried at room temperature under vacuum. The sample in each well was reconstituted before the CE analysis with 10 pL deionized water. The... 

The outlet from the column is connected to a detector usually fitted with an automatic recorder that permits exclusively the monitoring of the relative concentrations of the various constituents present in the sample. However, one may also make use of an automatic fraction collector duly attached to the outlet from the column, if required. The various experimental parameters stated below are normally given in the official monograph, namely ... 

Chromatography and Electrophoresis of Antigens. Cotton dust (20-30 mg) was dissolved in water and passed through a small column (30 x 1.5 cm id) packed with 3 g of Sephadex G-75 that had been preswelled in water. Chromatograms were obtained with an LKB Uvicord ultraviolet monitor and a chopper bar recorder. Volumes of 5 ml each were collected in test tubes with an automatic fraction collector. Two components were detected at 250 nm. Samples of 10 mg were analyzed by disc gel electrophoresis according to procedures described by Davis (36), and Zacharius (37). 

Magnesium speciation (Section ni.A) in serum was carried out using an anion exchange column for protein separation, with mobile phase at pH 7.4 the effluent was collected in an automatic fraction collector. On-line quantitation of the protein fractions was carried out by DA-UVD, and Mg determination was carried out from the automatic sampler in a GFAAS apparatus, measuring at 202.8 nm . ... 

The separated components emerging from the column in the eluent are usually collected as discrete fractions. This may be done manually by collecting specified volumes of eluent in Erlenmeyer flasks or test tubes. Alternatively, if many fractions are to be collected, a mechanical fraction collector is convenient and even essential. An automatic fraction collector (see Figure 3.6) directs the eluent into a single tube until a predetermined volume has been collected or until a preselected time period has elapsed then the collector advances another tube for collection. Specified volumes are collected by a drop counter activated by a photocell, whereas a timer can be set to collect a fraction over a specific period. 

In some experiments the column effluent is run to waste after passing through the appropriate monitors. In all other cases some kind of automatic fraction collector is used. 

Release of hydrocortisone. Initial exploratory in vitro studies designed to ascertain the usefulness of this polymer system have been carried out with a polymer based on 1,2,6-hexanetriol and various alkyl ortho esters. In these studies 2 wt% hydrocortisone was physically mixed into the ointment and the mixture placed into an erosion cell. A pH 7.4 buffer solution was then pumped across the cell at 9.5 ml/h, samples collected using an automatic fraction collector and analyzed for hydrocortisone by HPLC. The same study was also carried out by mixing into the ointment 2 wt% hydrocortisone and 2 wt% adipic acid. Results of these studies are shown in Fig. 32 [49]. The data clearly shows that without the incorporation of an acidic excipient erosion rate of the polymer is so slow that no hydrocortisone is released for two days. However, when an acidic excipient is mixed into the polymer, a fairly constant release is obtained. 

In TLC separated sample bands can be recovered directly from the plate without difficulty (2). Automatic fraction collectors can be quite useful in column chromatography. The latter are available in a variety of forms and degrees of complexity. For a general review see Refs. (/) and (31). For a discussion of the limitations of different fraction collectors, see Refs. (32-34). Ideally, each fraction collected should contain a single sample band this can be achieved by devices which change fractions when the detector senses a minimum between two peaks [v-h of Fig. 13-1 sec discussion of Ref. (/)]. 

At present, an off-line combination is in use in most instances. The mobile phase is collected batchwise and the fractions containing the substances of interest are then analysed by mass spectrometry. Huber et al. investigated the batchwise co]lection of eluent fractions with special reference to high-performance column liquid chromatography, and was able to elute components in a few seconds in a volume of less than 100 pi. The design of an automatic fraction collector ful-... 

Of late automatic fraction collectors, as employed in chromatographic work, have also become of importance in distillation at atmospheric pressure. These devices generally have a rotating table, on which test-tubes are arranged in a circle or spiral. The princijdes according to which they can function are the following ... 

Distillate take-off by an automatic fraction collector (section 7.6) ... 

An automatic fraction collector, containing 60 receivers, with sj-phon control (Fig. 324). 

To measure the substances eluting from the column, fractions of mobile phase can be collected and the concentration of the separated components measured externally—for example, in a spectrophotometer or using a pH meter. An automatic fraction-collector which collects a defined volume of column effluent in test tubes is sometimes employed. However, it is more convenient to employ a continuous-detection device at the exit of the column. The detector can be selective (for instance, it detects ultraviolet-absorbing or fluorescent compounds only) or universal (that is, it detects all components). In some cases, two detectors placed in series are used to gain additional information. The detector output is usually displayed on a strip-chart recorder or some other data-acquisition device. For quantitative analysis, an integrator or a minicomputer are useful to automatically measure peak areas. 

The solvent system is ethyl acetate ethanol water=3 l 3, with heavy phase as the stationary phase, the light phase as mobile phase the solute acetyl acetone (AR) acetyl acetone solution 5 mg/ml as the feed liquid automatic fraction collector spiral countercurrent extraction device ... 

And then switch to the left side, pump the mobile phase into the tube still the flow rate of 6 ml/min. At the same time, effluent liquid is collected every 2 minutes with automatic fraction collector in right side, until the solute can t be detected in the effluent. 

Collecting effluent fractions manually can be both boring and time consuming. A range of automatic fraction collectors are available commercially. Tliey are designed to collect a definite... 

The electrophoresis was usually carried out over a period of 18 hours in the cold room with an applied voltage of 400 v. providing a current of approximately 5 ma. Following the conclusion of the separation the packed column was removed from the system by disconnecting the plastic tube at the bottom and was placed over an automatic fraction collector. Three drops of material were then collected in each fraction and were analyzed by the modified Folin procedure or by ninhydrin analyses to determine the various peaks. 

The mixture of sugars is introduced on the column as a thick sludge in cellulose powder, prepared by making the sugars into a sirup with a little water and stirring in dry cellulose powder. After the porcelain disc and the solvent have been removed above the surface of the cellulose column, the sludge is placed on the top of the coltunn and covered with a layer (2 cm. thick) of dry cellulose powder. The porcelain plate is replaced and the solvent is allowed to flow through the column. The effluent is collected on an automatic fraction collector. 

Gross and Pitt-Rivers (18) described a technique for the separation of TRITh and Tx on a column of kieselguhr by a modification of the Gronk-vist-Hellberg (13) procedure. The stationary phase used is 0.5 N NaOH and the mobile one is n-butanol mixed with 20% chlorofonn. The preliminary treatment of the adsorbant, the preparation of the column, and the fractionation of the effluent are carefully described in the originai paper. The samples separated by an automatic fraction collector must be tested for radioactivity in order to locate and, eventually, identify the labeled constituents of the mixture. Radiochromatography of some of the fractions may be necessary to control their homogeneity or for identification purposes. 

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