Sampler application

Ockenden, W.A. Corrigan, B.P. Howsam, M. Jones, K.C. 2001, Further developments in the use of semipermeable membrane devices as passive air samplers Application to PCBs. Environ. Sci. Technol. 35 4536-4543. 

A universal sampler applicable to the majority of pesticides would be an ideal sampling device. In this study, personal sampling and analytical methods were developed and validated in the laboratory for determining workplace exposure to several pesticides. The major objectives of the study were to standardize on specific sampling media and to develop and validate methods using filter/ sorbent sampling trains. 

Mazzella, N., J.-F. Dubemet, and F. Delmas. 2007. Determination of kinetic and equilibrium regimes in the operation of polar organic chemical integrative samplers application to the passive sampling of the polar herbicides in aquatic environments. J. Chromatogr. A 1154 42-51. 

Figure 10 Modem robotic TLC apparatus (AR2I). 1. Robotic arm ORCA, 2. auto-sampler, 3. sampler applicator As30.DESAGA, 4. densitometer CD 60-DESAGA, 5. IBM-PC compatible, 6. printer, 7. oven, 8. OPD system, 9. classical tank, 10. plate holder, 11. finger holder.

This experiment describes the construction of an air sampler using an aquarium pump, a flow meter, a filter holder, and bottles that serve as traps for analytes. Applications include the determinations of SO2, NO2, HCHO, and suspended particulate matter. 

Hydraulic-drive samplers are also available, but cost factors tend to be substantially greater than electromechanical units. Recent use of hydraiilic-drive systems has diminished with the availability of increased strength and durabihty electric-motor linear-drive units capable of reliable operation in high-capacity applications. 

A second fully automated device, the HPTLC applicator AS 30 (described earlier), can be employed in connection with a sampling device. Automated refilling of the syringe is performed by editing a volume factor, e.g., 10 for application of 10 times 100 pi. This device can be recommended if loss of sample is not relevant (e.g., owing to automatic rinsing operations that afford at least 70 pi dead volume for a minimal 20-cm tube connection). However, the fully automatic mode is not recommended for valuable samples. Sample volume still present in the Teflon tube between the sampler and AS 30 syringe will be wasted and lost because this operation cannot be circumvented by the user. 

In the oxamyl tomato study, the DFR samples were obtained using a 5-cm Birkestrand sampler (10-cm disk size using the upper and lower surfaces). The sample consisted of 40 leaf disks or 400 cm from each subplot. The samples were collected impartially or in a nondirected approach from the middle two rows. The plot was four rows wide and the tractor came into contact with the first and fourth rows as the application was made. The middle two rows should be undisturbed by this movement and should therefore provide a more representative sample. 

The present authors have had experience using rotary samplers for field studies involving relatively small droplets for vector control applications and for the measurement of droplet size at far-field distances. When using magnesium oxide slides, the spread factor for droplets varies from 0.75 for crater diameters up to 15 jam, to 0.8 for 15-20 p.m and 0.86 for crater diameters above 20 am. 

Litten, S., B. Mead, and J. Hassett. 1993. Application of passive samplers (PISCES) to locating a source of PCBs on the Black River, New York. Environ. Toxicol. Chem. 12 639-647... 

For certain bioanalytical applications such as those described in the previous section, it is desirable to collect analytes of interest while separation in the tPLC system takes place (e.g., for follow-up by MS). To collect the analytes, the tPLC system may be equipped with a time-triggered fraction collection mechanism. This system allows the selection of time intervals in which samples will be diverted (after passing through the detectors) to the selected wells of microtiter plates. Figure 6.11 shows an overall view of a system with time-triggered fraction collection capabilities. Figure 6.12 depicts the system along with a detailed view of the collection sampler employed. 

Terms used, methods of sampling, and sample handling will be different for water and submerged solid and semisolid samples. The methods described earlier (i.e., transect and grid sampling) are also applicable to these situations. However, semisolid samples, such as those obtained from lake bottoms, require a special sampler. 

Key instruments required for HPTLC analysis includes a sample application device, similar to the Automatic TLC Sampler 4, a digital... 

More recently, Harner et al. (2003) coated ethylene vinyl acetate (EVA) onto glass (polymer coated glass [POG]) for use as fugacity sensors or equilibrium samplers of SVOCs in indoor and outdoor air. The EVA film fhickness was 1.1 and 2.4 qm depending on the application and as expected, SVOC sorption capacity and times to equilibrium were shown to be directly proportional to film thickness. The clearance capacity Ey volume of sample medium cleared of chemical) of a sorbent for an analyte is given by... 

Table 1.1 Comparison of Passive Sampler Characteristics and Applications for Organic Compounds... 

Similar to the previous section, we discuss only selected works to highlight the development of SPMDs. Also, we include some discussion of several unpublished pilot smdies (Huckins, 1989) that influenced our early development of SPMDs. These pilot studies were directed solely toward sampling the aqueous phase. The flrst application of SPMDs for sampling organic vapors did not occur until several years later (Petty et al., 1993). To our knowledge, only SPMDs, PESs and SPMEs are being applied in both air and water, because the use of many passive samplers is limited to a specific medium and exposure scenario. 

Petty, J.D. Huckins, J.N. Zajicek, J.L. 1993, Application of semipermeable membrane devices (SPMDs) as passive air samplers. Chemosphere 27 1609-1624. 

Petty, J.D. Huckins, J.N. Robertson, G.L. Cranor, W.L. Gale, R.W. Alvarez, D.A. Clark, R.C. 2002, The application of semipermeable membrane devices (SPMDs) as samplers of airborne contaminants in indoor air. Presented at die 53 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 16-22, 2002 New Orleans, LA. 

The authors have been intimately involved in eondueting research to address many aspects of environmental contaminants for about three decades. Historically, samples of environmental matrices, particularly water and air have been collected at narrow windows of time (i.e., minutes or several hours) which are not representative of the exposure experienced by organisms. Consequently, we initiated the development of what would ultimately be the semipermeable membrane device (SPMD). The SPMD has subsequently proven to be an effective passive sampler for a wide range of hydrophobic contaminants in multiple media. To date, there are more than 180 peer reviewed publications in the open scientific literature, where SPMDs are used for a variety of applications. Some of these publications are critical of the use of passive samplers for certain applications. However, constructive criticism has greatly aided in defining information gaps and limitations of the passive sampling approach. 

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