Detectors thermionic specific

Gas chromatograph equipped with a thermionic specific detector (TSD) DB-5 Megabore capillary column, 30 m x 0.53-mm i.d. 

Varian 3400 with thermionic specific detector RestekRtx-5,30-m x 0.53-mmi.d., 1.5- xmfllmthickness... 

Instrumental Analysis. A Hewlett-packard Model 5880 A GC, equipped with thermionic specific detector and a 50 m x 0.23 mm i.d. fused silica capillary column coated with Carbowax 20m, was used for quantitative analysis of thiazolidine and 2-acetylthiazolidine derived from formaldehyde and methyl glyoxal, respectively. GC peak areas were calculated with a HP 5880 A series GC integrator. The oven temperature was programmed from 70 to 180°C at 2 C/min. A Finnigan Model 3200 combination GC/MS equipped with an INCOS MS data system was used for mass spectral identification of thiazolidine derivatives. 

The thermionic specific detector (TSD), also called the alkali flame ionization detector, is really a FID with a bead of an alkali metal salt such as Rb or Cs. A schematic is shown in Fig. 4.28. The TSD shows... 

A selective thermionic specific detector (TSD) was developed by Albert (107) but it is more commonly referred to as a nitrogen-phosphorous detector (NPD). It is basically an alkali FID. Figure 13.36 compares the TSD and the microcoulometric detector. More resolution is obtained through the TSD with elimination of the mixing in the transfer line, reactor tube, and titration cell of the... 

TSD Thermionic specific detector (term also used for nitrogen-... 

Gas chromatograph fitted with a thermionic nitrogen-specific detector Gas chromatograph fitted with a quadrupole mass-selective detector... 

GC is coupled with many detectors for the analysis of pesticides in wastewater. At the present time the most popular is GC-MS, which will be discussed in more detail later in this section. The flame ionization detector (FID) is another nonselective detector that identifies compounds containing carbon but does not give specific information on chemical structure (but is often used for quantification because of the linear response and sensitivity). Other detectors are specific and only detect certain species or groups of pesticides. They include electron capture,nitrogen-phosphorus, thermionic specific, and flame photometric detectors. The electron capture detector (ECD) is very sensitive to chlorinated organic pesticides, such as the organochlorine compounds (OCs, DDT, dieldrin, etc.). It has a long history of use in many environmental methods,... 

For amines absorption in an acid solution, or preferably adsorption onto an acid ion exchange column (acidified divinylbenzene-styrenesulfonic acid copolymer) is used. 10-50 1 of ambient air is sent over a wet 100 mmx 3 mm I.D. column the ion exchange polymer is put into a vial, made alkaline and the water solution is analysed on packed Carbowax-KOH GC-column with a thermionic selective detector (TSD), which is specific for nitrogen- and phosphorus-compounds. Trimethylamine is detected easily at 1 ppb. 

The alkali flame ionization detector (AFID) or thermionic detector (TID) is a specific detector used primarily in the trace analysis of pesticides particularly those containing phosphorus. 

Verwej et al. [175] have described a procedure for the determination of PH3-containing insecticides in surface water. In this procedure the insecticide is hydrolysed to methylphosphonic acid, and the acid is concentrated by anion exchange and converted to the dimethyl ester. After clean-up on a microsilica gel column the ester is analysed by gas chromatography using a thermionic phosphorus-specific detector. Detection limit is lnmol L 1. 

The nitrogen phosphorus detector (NPD) (sometimes called the thermionic detector) is another sensitive, but, in this case, a specific detector, that is based on the FID. Physically the sensor appears to be similar to the FID but, in fact, operates on an entirely different principle. A diagram of an NPD detector is shown in figure 9. 

HPLC = high-performance liquid chromatography LOD = level of detection NPD =nitrogen-phosphorus detector PRA = pararosaniline RSD = relative standard deviation SPE = solid phase extraction PSD = thermionic specific detection UV = ultraviolet absorbance detection... 

Separation of hydrazine and dimethylhydrazines from environmental samples is by acid extraction when necessary. Air samples are usually collected in a bubbler with acid or on an acid-coated silica gel (NIOSH 1977a, 1977b, 1984). When GC is employed, detection may be by electron capture detector (ECD), FID, nitrogen-specific detector (NSD), thermionic ionization detector (TID), and/or MS as described above (Section 6.1). 

ECD = electron capture detection FID = flame ionization detector GC = gas chromatography MS = mass spectroscopy NSD = nitrogen specific detector TID = thermionic ionization detector... 

GC can achieve the highest resolution of the essential oils, but there are some significant limitations with regards to preparative scale separations. Typically, as the sample capacity is increased, the resolution of the chromatographic separation is reduced. On a lab scale, equipment is available that permits 24-hour automated and unattended separations, however, the recovery yield and sample resolution are still problematic [57]. Capillary column GC has become so routine for essential oil analysis that one rarely finds a lab without that capability. A multitude of detectors exist for GC thermal conductivity (TCD), flame ionization (FID), flame photometric (FPD), thermionic specific (TSD), photoionization (PID), electron capture (ECD), atomic emission (AED), mass spectrometry (MS), and infrared spectroscopy (FTIR) [58,59]. The TCD is used primarily with preparative-GC (packed column) because it is... 

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