Detector limits

DETECTOR LIMITED OPERATION OF OPEN TDBDLAR COLOMNS... 

In this method an Ar+ laser-pumped rhodamine 101 laser was used as the heat and probe source. The signal from a silicon photocell with a 1 mm2 photosensitive surface, which was used as a laser radiation detector, was processed with an inexpensive personal computer. The detector limit is 5 pg of phosphorus/ml. 

The concentration of each volatile must be high enough for gaslight syringe extraction, but low enough that the SPME fiber is not saturated and the GC detector limits are not exceeded. An acceptable concentration must be determined empirically by interative application of the two extractions. 

If another GC peak resulting from SPME of the sample or other extractions is larger than the peak observed, the fiber is not saturated. Saturation can be tested (see Critical Parameters). If the fiber is saturated, or if the GC peak is flat at the top or exceeds the detector limits, the static extraction and SPME analysis should be repeated with a less concentrated solution. 

Detectors for Gas Chromatography (continued) Detector Limit of Detection Linearity... 

A schematic of a typical Johann spectrometer on a tokamak is shown in Fig. 8.1. Typically, the detectors limit the resolution, as long as gas detectors are used. 

However, analysis becomes much more complex when stereoisomers are quantified separately (Figure 50.1). Enantiomers cause identical detector responses in NPD, FID, or MS. Therefore, chiral separation systems are required to overcome these detector limitations. Despite enormous progress in separation media and detector systems within the last two decades the number of reports on chiral analysis of nerve agents valuable for toxicokinetic studies is... 

CRP was subsequently shown to be an acute phase reactant and important in the nonspecific host defense against inflammation, especially infection (see Chapter 20) and is routmely monitored as an indication of infection and autoimmune diseases using methods having detector limits of3to8mg/L. 

The dynamic range of the detector limits the intensity differences that are recordable on one image. The higher the dynamic range the better one is able to characterize signals having a strong contrast. 

Detector Limit of Detection (gS/s) Linear Dynamic Range (decades) Selectivity ... 

Molecular structures which are present in both the solvent used as the mobile phase and the eluted compound often give a low but measurable detector response. The resulting background signal, which is often higher than that for GC detectors, limits the lower detection limit. This is one of the reasons why there is still a lack of highly sensitive universal LC detectors [14, 15]. 

Detector limited operation of open tubular columns in liquid chromatography q = 10" N.s/m Dm =... 

This is obvious in cases where known compounds fail to elute. However, these restrictions may be subtle, and potentially more costly, when the thermal stability and volatility of the sample components is unknown. HPLC is restricted by detector limitations -- detector choice is a guessing game when the analytes are unknown. SFC is superior to GC and HPLC for the first screening of many new samples. For this purpose SFC provides ... 

A more complete picture of what is present within its mass range (provided by the FID) than is possible by HPLC with its detector limitations. 

Detector limits (weight ppm) 50-1,000 2,000-5,000 WDS used at higher beam current, fewer overlapping peaks XEDS better if current is restricted, e.g., to avoid beam damage... 

Analyze 50 pi of the dissolved, filtered sulfation reaction using the analytical RP-HPLC column with a Hnear gradient of HPLC buffer B from 5% to 60% over 40 min. If using an HPLC with a detector limited to one wavelength, monitor at 220 nm. 

The on-column approach to CE absorbance detectors limits the path length to the ID of the CE capillary. The path length for a 50 pm ID capillary will be 200 times shorter than that of a common 1 cm cuvette. The short path length significantly limits the sensitivity of CE absorbance detectors (see Table 2). A number of absorbance cells have been designed to increase the detection path length (see Figure 3). The... 

The measured Tsf was later found to be detector limited using an Hg-Cd-Te (77 K) detector with a response of 120ns, Tsf was measured to be 150ns (Hubert et al. 1990). A pulsed excitation could provide in some cases a single pulse emission as shown in fig. 10. 

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