Detection response

The results obtained from A-II injected animals (Figure 15) confirmed that the peak arterial pressure response is a reliable indirect indicator of A-II absorption (27,25). On this basis it is very unlikely that oral administration of A- II-impregnated resin (Figure 16) resulted in any significant absorption, even at an A-II dose which was 25X higher than the maximally effective subcutaneous dose. As in the insulin studies, the detectable response was observed about two and one-half hours after dosing. 

Leak and shock detection Response time <1 min High accuracy (<1%)... 

Pressure detection shall be used for closed enclosure applications. Threshold detectors provide an electric signal when a preset overpressure is exceeded. Dynamic detectors provide an electric signal to the control and indicating equipment (CIE). Typically they have both rate-of-rise and pressure threshold triggering points that can be configured specifically to the application conditions. Although this type of detector minimizes spurious activation of the isolation system (due to pressure fluctuations other than explosion pressure rise), care shall be taken to set up such detectors to meet appropriate detection response criteria for the particular application and protected enclosure geometry. 

As far as fruit and vegetables are concerned Ripper proposes the following tolerances. At these dosage rates no detectable response or injury is manifested since the detoxicating mechanisms of the human body are able to inactivate the insecticide ... 

After determining a concentration of test compound which elicits no visually detectable response or effect in the aquatic species over a period of 48 hours (Step 1), fresh animals are placed in the chamber, exposed to known concentrations of test chemical (usually 14C-labelled), and the uptake rate and major metabolites determined (Step 2). Depuration rate from the dosed animals also can be estimated at this point by transfer to untreated water. Fresh animals also can be exposed to a constant flow of test solution until an absorption-excretion equilibrium (steady state) has been established, dosed briefly with labelled compound, and release (turnover) rate determined (Step 3). 

If the purpose of gel electrophoresis is to identify low-abundance proteins (e.g., low-copy-number proteins in a cell extract or contaminants in a purification scheme), then a high protein load (0.1 to 1 mg/ml) and a high-sensitivity stain such as silver or fluorescence should be used. When the intention is to obtain enough protein for use as an antigen or for sequence analysis, then a high protein load should be applied to the gel and the proteins visualized with a staining procedure that does not fix the proteins in the gel, e.g., colloidal CBB G-250 (Subsection 8.2.8.1). Furthermore, for purposes of quantitative comparisons, stains with broad linear ranges of detection response should be used. 

As effect parameters studied in in vitro assays become more refined, the question becomes more important of how to interpret the findings in terms of toxicity. For example in transcriptomic experiments, very low exposures in the EST which do not affect cellular endpoints of proliferation and differentiation can be shown to affect gene expression (46). The question arises at what level of response the observed effect reaches the level of adversity. Evidently, many physiologic responses are beneficial, neutralizing the hazard by homeostatic control and therefore not all detectable responses should be characterized as toxic or adverse. It may not even be possible to answer this question on the level of an individual test, but this may require a more integrated approach using weight of evidence over a combination of results from different assays. 

Tire means by which chemicals enter the body are inhalation (breadiing), ingestion (swallowing), and absorption (skin or living tissue contact). Once in the system these chemicals may produce such symptoms as tissue irritation, rash, dizziness, anxiety, narcosis, headaches, pain, fever, tremors, shortness of breath, birth defects, paralysis, cancer, and death, to mention a few. The amount of chemical diat enters the body is called the "dose." The relationship that defines the body response to the dose given is called the "dose-response curve." The lowest dose causing a detectable response is the "threshold limit." The "limit" is dependent on factors such as particle size of contaminant, solubility, breathing rate, residence time in the system, and human susceptibility. 

The studies with AFB serve to emphasize the importance of using sensitive toxicology test systems. The human cell system is sensitive to ng/ml concentrations of AFB, whereas bacteria mutagenicity test systems require Atg/ml AFB concentrations for a detectable response. The lower concentra-... 

Analyte Sample matrix Tissue Sensing element Linear range (mol 1 1) Limit of detection Response time Lifetime Ref. 

The final section addresses degradation and oxidation reactions in a commonly used derivatization system for cellulose, a mixture of DMSO and phenyl isocyanate to achieve cellulose carbanilation, e.g. for analytical purposes. Mechanistic studies were aimed at verifying the assumed oxidative action of this reaction system, and trapping methodology was employed to detect responsible intermediates. 

A linear detection response to amounts of water derived fulvic acids separated on the gas chromatography 100 column was obtained enabling direct measurement of amounts of fulvic acid in water samples. The detection limit was 40ng for copper EDTA and 12pg of fulvic acid. 

Under these conditions the detection response is substantially independent of the chemical form of the phosphorus compounds. 

FIGURE 2-13. High performance liquid chromatographic separation of unknown TV-nitroso compounds. The colorimetric, photometric, and fluorometric detection responses are shown. Column /uBondapak C]8 3.9 mm ID x 30 cm. Mobile-phase composition was programmed from 20 to 80% acetonitrile in water (pH = 4, phosphoric acid) over 20 min, was held isocratic (constant mobile phase composition) for 22 min, and then was programmed from 80 to 100% acetonitrile in 1 min and held at 100% acetonitrile for 20 min. The flow rate was 1.0 mL/min. (Reprinted from reference 10 with permission. 

Quantification of aroma compounds using GC and internal reference has long been a problematic issue.81 Detection response factor, peak shape, discrimination phenomenon at the injector port, and, of course, disproportion during sample preparation were more or less unavoidable. Stable isotopes used as internal standards combined with an MS detector have realized reproducible and far more accurate quantification. The major drawback of this method is the tedious process of preparing the isotope-labeled standards. 

Although the hindgut showed high sensitivity to the LK s, other t3rpes of visceral muscle were less responsive. The foregut and oviduct, for example, were 100-1000 fold less sensitive than the hindgut. A concentration of more than 10" M of each of the peptides was required to elicit a detectable response from these... 

Agent Gas detection tube Limit of detection Response time... 

Range of calibration, limits of linear detection response, that is where the signal/sample load is within 5%. 

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