In situ sample

The short-term exposure of humans, animals, and plants to gaseous pollutants is more severe than that for pollutants in other matrices. Since the composition of atmospheric gases can show a substantial variation over a time, the continuous monitoring of atmospheric gases such as O3, CO, SO2, NH3, H2O2, and NO2 by in situ sampling is important. 

NIOSH. 1979. Final report. In situ sampling techniques in environmental air analysis. Report no. 5-R01-OH-00632-02. Cincinnati, OH U.S. Department of Health, Education, and Welfare, National Institute of Occupational Safety and Health. NTIS publication no. PB84-241439. 

Table 1 summarizes several of the experimental methods discussed in this chapter. A need exists for new or revised methods for transport experimentation, particularly for therapeutic proteins or peptides in polymeric systems. An important criterion for the new or revised methods includes in situ sampling using micro techniques which simultaneously sample, separate, and analyze the sample. For example, capillary zone electrophoresis provides a micro technique with high separation resolution and the potential to measure the mobilities and diffusion coefficients of the diffusant in the presence of a polymer. Combining the separation and analytical components adds considerable power and versatility to the method. In addition, up-to-date separation instrumentation is computer-driven, so that methods development is optimized, data are acquired according to a predetermined program, and data analysis is facilitated. 

Diffuse reflectance FTIR (DRIFT) spectra were recorded on a Bio-Rad FTIR spectrometer (EXCALIBUR FTS3000). A high-temperature cell was attached to a flow system that allows in-situ sample treatment, adsorption and desorption of probe molecules at different temperatures. 

Figure 7.4 STM chamber in situ sample heating system.

Fig. 14 Autonomous unit vehicle, in situ sampling device...

H. Claustre, S.B. Hooker, L. Van Heukelem, J.-F. Berthon, R. Barlow, J. Ras, H. Sessions, C. Targa, C.S. Thomas, D. van der Linde and J.-C. Marty, An intercomparison of HPLC phytoplankton pigment methods using in situ samples application to remote sensing and database activities. Marine Chem. 85 (2004) 41-61. 

Fig. 3.97. Comparison of ion-pair chromatography separations of RB5-H and metabolites by on-line and in situ sampling coupled to HPLC-DAD from bioreactor (A) 585 nm scanning wavelength, (B) 270 nm scanning wavelength. Peak identification TAHNDSDP1 = 7-amino-8-hydroxy-l,3-naph-toquinone-3,6-disulphonate-l,2-diamine TAHNDSDP2 = dihydroxynaphtoquinone-3,6-disulphonate-diimine p-Base = 2-(4-aminobenzenesulphonyl)ethanol. Reprinted with permission from A. Plum et al. [156],...

When the k and SPMD-water partition coefficient of the PRC are known, its Rs can be calculated from Eq. 3.20. More precisely, we assume that the PRC is representative of the in situ sampling rates of target compounds with similar physicochemical properties as the PRC. Various approaches have been used to estimate sampling rates for all analytes from the PRC-derived sampling rates (see Section 3.6.). 

Implications of DOC Sorption in the Lab for In Situ Sampling Rate Estimates... 

When environmental conditions at an exposure site differ from those used for laboratory calibrations or when calibration data for an analyte are not available, at least one SPMD per site is spiked with PRCs. The type of compounds used for PRCs and their spiking levels were discussed earlier. PRC samples and standard SPMD samples (i.e., field-deployed SPMDs) differ only by the presence of the PRCs. Handling, processing and analysis are also identical. As implied above, the purpose of the PRC sample is to provide data for estimation of in situ sampling rates of target compounds. 

This requirement for a large increase in temperature below the phase boundary may have enabled the MAT Gautamala 2 sample to survive the trip from seafloor to shipboard. However, upon recovery and heating of smaller, more dispersed in situ samples at the three-phase condition, dissociation will begin almost immediately, so that the sample may not survive nonpressurized recovery. In contrast to small hydrates, massive hydrates are aided in slow dissociation by a low surface to volume ratio, together with the protective formation of an ice layer by the dissociated water (Yakushev and Istomin, 1991 Gudmundsson and Parlaktuna, 1992). 

Start with batch of floodplain sediment samples from in situ sampling Drying at 40°C... 

The study of sulfide metabolism at hydrothermal vents dictated the development of methods that could process hundreds of samples which contain complex mixtures of sulfur compounds in a variety of blood, seawater and tissues samples. In addition, we needed the capability of using "S-radiolabeled compounds for the tracing of complex sulfur metabolic pathways in bacteria and animal compartments of the different hydrothermal vent symbioses. In some instances, in situ sampling by submersibles at depths of 2500 meters with associated recovery times of two hours necessitated the remote derivatization of samples at depth prior to recovery. None of the above methods completely met our needs. We have adapted the bimane-HPLC method (24.351 for shipboard use and have found it a particularly robust method for studying a number of questions concerning the role of reduced sulfur compounds in the marine environment. 

Stabilized liquid membrane device (SLMD) A water-insoluble organic complexing mixture diffuses to the exterior surface of the sampler through a polymeric membrane Divalent metal ions Preconcentration, in situ sampling, determination of labile metal ions in grab samples Days to several weeks Extraction with acid 73... 

Sayles F.L. (1980) The solubility of Ca(X>3 in seawater at 2°C based upon in-situ sampled pore water composition. Mar. Chem. 9, 223-235. 

---