Flame photometric detector performance

EC = electrical conductivity detector ECD = electron capture detector FPD = flame photometric detector GC = gas chromatography HPLC = high performance liquid chromatography NPD = nitrogen phosphorus detector TID = thermionic detector UV = ultraviolet spectroscopy... 

Elimination of wet chemical sample preparation enables a complete analysis to be performed and data to be quickly analyzed. The detection limits are in the low part-per-million range using mass spectrometric detection. Alternatively, detection of compounds can be achieved by all common gas chromatography detectors (flame ionization detector, electron capture detector and flame photometric detector), and detection limits are determined by the method of detection employed. 

The amount transformation process is illustrated with data for chlorpyrifos in the flame photometric detector, phosphorus mode, and shown in Table VI. Level 1 transformations were calculated where the amount power was increased by 0.03 units for each step. At an amount power of 0.20 the F statistic of 32.7 showed a minimum but at a confidence level of 95% did not satisfy the F test for linearity. Power steps changed by only 0.01 and 0.001 units in the vicinity of the minimum were then calculated as shown in levels 2 and 3. The best linearity was found in this case at a power transformation of 0.182 although the F statistic of 8.33 did not indicate linearity when compared with the critical F of 2.99 at P=.95. Calculations at these second and third levels were not always necessary and even when performed did not always lead to a satisfactory condition of linearity. 

Continuous Sampling and Determination. There are no truly continuous techniques for the direct determination of sulfuric acid or other strong acid species in atmospheric aerosols. The closest candidate method is a further modification of the sensitivity-enhanced, flame photometric detector, in which two detectors are used, one with a room-temperature de-nuder and one with a denuder tube heated to about 120 °C. Sulfuric acid is potentially determined as the difference between the two channels. In fact, a device based on this approach did not perform well in ambient air sampling (Tanner and Springston, unpublished data, 1990). Even with the SF6-doped H.2 fuel gas for enhanced sensitivity, the limit of detection is unsuitably high (5 xg/m3 or greater) because of the difficulty in calibrating the two separate FPD channels with aerosol sulfates. 

Note TLC, thin-layer chromatography HPLC, high-performance liquid chromatography GLC or GC, gas-liquid chromatography AA, atomic adsorption NPD, nitrogen phosphorus detector FPD, flame photometric detector GC/MS, gas chromatography/mass spectrometry. 

Various alkyl and aryltin compounds were determined in aquatic matrices, namely sediments, biota and water by means of gas chromatographic methods. In this work, comparisons of single or dual flame photometric detectors and electron capture detectors were reported (Tolosa et al., 1991). Sample preparations included acid digestion, extraction, formation of methyl derivatives and clean-up with alumina prior to gas chromatographic analysis. With the electron capture detector, cold on-column injection of organo-tin chlorides was studied. The conclusion was that a single or dual flame photometric detector equipped with a 600 nm interference filter yielded the best performance for determinations of tin species as methyl derivatives. Detection limits for the method using flame... 

Py-GC experiments were performed using a modified SGE pyrolysis inlet, interfaced either with a Chrompack gas chromatograph (model 437S) equipped with a flame ionization detector and a double flame photometric detector or with a Delsi gas chromatograph (model DI300) interfaced with a Delsi mass spectrometer (model R10 10). The control of the Chrompack GC and the data acquisition were done with a PCI-Chrompack program and a PC computer. 

The separation performance and sensitivity of a capillary electrophoresis system coupled to a phosphorous-specific flame photometric detector (FPD) has been reported for the detection of alkylphosphonic acids l20 221. The liquid junction used to decouple the electric field from the FPD showed a negligible influence on the performance of the system as compared with online UV detection. The use of an on-column sample stacking preconcentration technique allowed for injection of 900 nL. With the large injection, the detection limits for the alkylphosphonic acids in water were 0.1-0.5 xgmL 1. 

GC-FID gas chromatography with flame ionization detector, HPLC-UV high performance liquid chromatography with UV detector, LC-MS liquid chromatography coupled with mass spectrometry, GC-FPD gas chromatography with flame photometric detector... 

In trace analysis of contaminant substances, one can use specific detectors for certain compounds, such as a nitrogen-phosphorus detector (NPD), thus gaining detection ability for nitrogenated and phosphorylated compounds the electron-capture detector (ECD) shows excellent performance for chlorinated substances and the flame photometric detector (FPD) is the most widely used for sulfur-containing compounds. 

Traditionally, gas chromatography (GC) was the preferred approach for the analysis of pollutants in water, due to the high sensitivity and selectivity achieved, thanks to its selective detectors such as the nitrogen-phosphorus (NPD), the flame photometric detector (FPD), and electron-capture detector (ECD), and to the ease of coupling to mass spectrometry (MS). However, high-performance liquid chromatography (HPLC or LC) is the most powerful approach for the determination of polar, nonvolatile, and thermolabile compounds (i.e., those which are not GC amenable). 

The Shimadzu GC-15A and GC-16A systems are designed not only as independent high-performance gas chromatographs but also as core instruments (see previously) for multi-GC systems or computerised laboratory automation systems. Other details of these instruments are given in Table 5.1. The Shimadzu GC-8A range of instruments do not have a range of built-in detectors but are ordered either as temperature-programmed instruments with thermal conductivity detection (TCD), flame ionisation detection (FID), or flame photometric detectors (FPD) detectors or as isothermal instruments with TCD, FID, or electron capture detectors (ECD) (Table 5.1). 

Tables 4.3 and 4.4 list several substances that have been used to simulate the nerve agent GB and bhster agent HD, respectively, in detector testing. The listed chemicals in Table 4.3 are similar to GB in some aspects. For example, the structure of dimethyl methylphosphonate (DMMP) is very similar to that of GB. Both contain the CH3-P=0 group. The main difference between them is that the simulant does not have the more active fluoride (-F) function group, and thus, its toxicity is much lower than GB. Both compound molecules contain phosphorous. Therefore, it is possible to use DMMP as a simulant to evaluate the performance of a flame photometric detector, ion mobility detectors, or surface acoustic wave detector.

Detector—Any flame photometric detector (FPD) can be used, provided it has sufficient sensitivity to produce a minimum peak height twice that of the base noise for a 4-pL injection volume of 0.5 mg/kg thiophene in benzene. The user is referred to Practice E 840 for assistance in optimizing the operation and performance of the FPD. 

Detectors commonly used in GC and specified in the USPP include FID, alkali FID (NPD, TD), BCD, and TCD. A description of these detectors, including their operational principles and relative performance, was presented in a previous volume of this encyclopedia. Various other useful detectors for GC include photoionization (PID), flame photometric (FPD), electrolytic conductivity (BLCD), redox (RCD) and sulfur chemiluminescence (SCD), and helium ionization (HID).[4 1 Table 1 summarizes some of the features of detectors used in GC. 

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