GC/MS/Computers

Section: Literature Citedmentioning

confidence: 99%

Plasma chromatography with laser-produced ions

Lubman¹,

Kronick²

1982

“…The exact method of probing the refractive index profile differentiates among the techniques. For example, the gradient of the refractive index is monitored in photothermal deflection spectrophotometry (PDS) (1, 4-7) and in moire deflectometry (8), and the effect of the curvature is monitored in thermal lens spectrophotometry (2, [9][10][11][12][13]. These techniques all have about the same absorbance sensitivity when the effects due to the particular solvent system and excitation laser intensity are taken into account (1, 3).…”

mentioning

confidence: 99%

Negative ion mobility spectrometry for selected inorganic pollutant gases and gas mixtures in air

Eiceman¹,

Leasure²,

Vandiver³

1986

4) Alcock. N. J.; Corbelli, L.; Games, D. E.; Lant, M. S.; Westwood, S. A.Spectra for inorganic gases common to combustion emisdons were obtained in air by using negative ion mobility spectrometry (NIMS). Gases were characterized individuaiiy from 10 to over 4000 ppb in alr and in two binary mixtures of S02/N02 and HCI/SOP. Spectra for HCI and SO2 were distinguished by single Intense peaks at reduced mobilities ( K O ) of 2.98 cm2/(V 8 ) and 2.30 cm2/(V s), respectively. The product ion for NO, had a KO of 2.80 cm2/(V 8 ) as determined using binary mixture studies and was unresolved otherwise from reactant Ions. I n contrast, NIMS spectra for H2S showed three peaks that were concentration dependent and had mobility values of 2.38, 2.28, and 1.70 cm2/(V 8 ) . Peak currents for H2S ranged from 10 to 50 pA and the estimated limit of detection (LOD) was 10 ppb. Peak currents for SO2 ranged from 15 to 65 pA and the estlmated LOD was 2 ppb. The range of peak currents for HCI was comparatively large at 140-215 pA and estimated LOD was <1 ppb. At constant concentration for HCI at 60 ppb, SO2 was added from 100 to 900 ppb. Competitive Ionization was observed in the order Of HCI > NO2 > SOP

“…These methods use either meter or oscillographic recorder output and they are tedious and of limited sensitivity. An early paper (5) reported a semi-automatic system for metastable defocusing of single precursors, and a very sophisticated automatic system which scans all precursor masses has been reported recently (6). Our own requirements fell between these two; we wanted the speed and sensitivity of a computer-controlled system, without the need for costly hardware additions to our DEC Lab8/e data system.…”

Section: Resultsmentioning

confidence: 99%

“…The combination of a gas chromatograph (GC) and a mass spectrometer (MS) has aptly demonstrated its utility as a powerful analytical tool. Many combinations of different types of instruments with different types of interfaces have been reported and these combinations have been thoroughly reviewed (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). The interface between the gas chromatograph and the mass spectrometer is the critical point in the combination and the majority of all GC/MS instruments contain some type of separator for pressure reduction and sample concentration.…”

mentioning

confidence: 99%

Techniques in gas chromatography/chemical ionization mass spectrometry

Hatch¹,

Munson²

1977

A gas chromatograph has been directly coupled to a magnetic mass spectrometer without a separator. With different source configurations both low pressure (El) and high pressure (Cl) mass spectra can be obtained. The direct coupling causes little loss In chromatographic resolution. Operating parameters of the instrument are discussed and examples of GC/CIMS are given. Flows as high as 20 ml/min (He, STP) or 10 ml/min (N2, CH4, STP) have been taken into the mass spectrometer without degradation of performance.