Separator, Watson-Biemann

Wall-jet cell (LC) 589 Watson-Biemann separator (GC/MS) 963 WCOT... 

The most common separators include the Ryhage or jet diffusion separator (74), the Watson-Biemann or pore diffusion separator (75), and the membrane solution diffusion separator originally developed by Llewellyn (75). The first two separators involve direct passage of the sample into the mass spectrometer the low molecular weight helium diffuses more readily and is pumped away. The membrane separator involves diffusion of the sample through a silicone membrane while the carrier gas vents to the atmosphere carrier gas is thus not confined to helium. There is no best separator the choice depends on the nature of the compounds, the temperature range over which it will be operated, and most usually what is available in a particular laboratory. A convenient configuration for a double-beam mass spectrometer such as the AEI MS-30 is two different separators, one into each beam, which permits rapid evaluation of separator performance. 

On the other hand, another mass spectrometer which utilized a Watson-Biemann separator showed poor sensitivity and could not be utilized for cannabinoid studies. 

Figure 1.5. Molecular separators a) Two stage jet separator due to Ryhage Typical dimensions are d, = ds = KT cm, dj = 2.5 x 1(T cm, d4 = 3x 10 cm, I, = 1.5 x 10 cm, I2 = 5x (F cm. The first chamber is evacuated with a mechanical pump and the second by diffusion pump, b) Silicone membrane separator [26] in which the GC effluent is channelled in a spiral path in contact with the membrane surface, c) Watson-Biemann fritted glass...

The mass spectrometric analyses initially reported in this communication were performed with a double focusing low resolution mass spectrometer Model 270, Perkin-Elmer Corp., Norwalk, Conn., coupled through a Watson-Biemann type of molecular separator with a gas chromatographic system. (Commercial sources and trade names are provided for identification only. Their mention does not constitute endorsement by the Public Health Service or by the U. S. Dept, of Health, Education, and Welfare.)... 

Analyte-enrichment interfaces for LC-MS show similarities with the interfaces used in packed colunm GC-MS, such as the jet separator, the Watson-Biemann fritted-glass, or the membrane interface. Various analyte-enrichment interfaces have been developed for LC-MS application, as discussed in Ch. 3.3.2. In API, gas-phase analyte-emichment is performed by means of a molecular-beam system. The vaporized column effluent is sampled from an atmospheric-pressure spray chamber via a differentially pumped expansion chamber system [3]. 

It was connected to a Varian 2700 series GC by a dual stage Watson--Biemann separator (250 C). The GC contained a 6 3% OV-1 packed glass column with an injection temperature of 250 C, and a helium carrier gas flow of 20 ml/min, (b) A Varian MAT-112 employing 0 8 KV, 70 eV, a 250 C source temperature and coupled by a slit separator (275 C) to a Varian 1400 series GC. A packed glass 6 3% OV-1 column and helium carrier gas at a flow rate of 20 ml/min was used. 

The GC to MS interface unit included a Biemann-Watson molecular separator [186], a GC stream splitter, and two Hoke needle valves (Hoke Inc., Cresskill, NJ, USA). One needle valve was placed in between the stream splitter and the molecular separator and the MS. The ion source pressure was maintained at approximately 1065-1335 x 10" Pa during the operation. The temperatures of the connection lines were maintained at 220-250 °C. 

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