Automatic samplers

Samples from municipal wastewater treatment plants and samples of industrial discharges often are collected as 24-h composites. Samples are obtained using an automatic sampler that periodically removes individual grab samples. The volume of each sample increment and the frequency of sampling may be constant or may vary in response to changes in flow rate. 

If the standard deviation of the lot caimot be estimated, a sampling program of greater sample size is required to generate an estimate of the standard deviation for future sampling operations. In some cases, sample size can be increased and sampling costs reduced by the use of automatic samplers. These offer a substantial reduction in labor costs but an increase in capital costs. 

Automatic sampler equipped with a 50-pL injection loop... 

Perkin-Elmer Model ISS-100 automatic sampler Kratos ABI Spectrofiow Model 783 ultraviolet/visible (UVmS) detector... 

Perkin-Elmer Model lSS-100 automatic sampler Kratos ABI Spectroflow Model 783 UV/VIS detector, VlCl EQ60 LC switching valve Supelcosil LC-CN, 33 x 4.6-mm i.d., 5-pm particle size... 

The above so-called automated titrations still require manual sample introduction directly into the measuring cell60 in order to avoid this in series analysis, a few manufacturers added automatic samplers, which in laboratory practice require only the previous introduction of samples into a series of cups... 

Apparatus. A constant rate displacement pump charged with mercury was used to displace the fluid of interest from steel cylinders to the core. A pressure transducer connected to the chart recorder provided the pressure history of each core flood. An automatic sampler with... 

LSC 2000 (concentrator) ALS 2016, 2032, (discrete automatic samplers) automatic sample heater ALS 2050 (vial sampling system)... 

Pollutant ( xg/L) automatic sampler grab composite automatic samples... 

An Ion Chromatograph has been successfully automated by interfacing it to an automatic sampler (7). Continuous unattended analysis was possible, the actual number of samples analyzed being limited by the ionic capacity of the suppressor column. The automated Ion Chromatograph was used to analyze soluble sulfates, ammonia and alkyl amines in stack and automobile exhqust samples. Excellent agreement between IC and automated barium chloroanilate titration for sulfate was obtained with a relative standard deviation less than 5%. 

Magnesium speciation (Section ni.A) in serum was carried out using an anion exchange column for protein separation, with mobile phase at pH 7.4 the effluent was collected in an automatic fraction collector. On-line quantitation of the protein fractions was carried out by DA-UVD, and Mg determination was carried out from the automatic sampler in a GFAAS apparatus, measuring at 202.8 nm . ... 

Analytical. Samples were chromatographed on a Hewlett-Packard 5880A gas chromatograph which was fitted with a 30M fused silica capillary column (DBS) and an automatic sampler. The GC was interfaced to a Hewlett-Packard 3354 Laboratory Automation System (LAS). Raw data was automatically transferred to the LAS where peaks were selected by retention time, integrated and stored in a processed file. Processed data was then transferred... 

If severe nonlinearities might be present, the linear inner relation can be modified to a quadratic or cubic one. This strong nonlinear situation might arise whenever problems occur on the detector or monochromator, malfunction of the automatic sampler in ETAAS, strong influence of the concomitants on the signal, when the linear range for the analyte is too short or when LIBS, LA-ICP-MS measurements or isotope dilution are carried out (see Chapter 1 for more possibilities). 

Kikkoman Corp., a soy sauce making company, developed an automatic chemical composition analyzer of soy sauce (Figure 9) [16]. The analyzer consists of an InfraAlyzer 400 or InfraAlyzer 500, a temperature controller, an automatic sampler and pumps. A certain amount of soy sauce collected by the automatic sampler is sent to the NIR analyzer at a constant flow rate by a pump through a temperature controller at 20°C. NIR measurement is made automatically. After the NIR measurement, the sample cell and tube are washed with cleansing liquid. It takes about 3 minutes to analyze one sample including washing process. 

Sampling Probe or automatic sampler Representative sample... 

Another part of the Midcontinent Herbicide Project involved nine stream sites equipped with automatic samplers that were monitored for triazine herbicides and their degradation products from April through July 1990. It was found that the use of microtiter plate ELISA provided a good semiquantitative measure of atrazine for concentrations less than 3.0 jg/E. At higher concentrations, the samples had to be diluted. Results from the ELISA screen compared with GC/MS results showed good agreement (Pomes and Thurman, 1991 Scribner et al, 1994). 

FIGURE 1.11 Basic components of an automatic sampler 1—sample intake 2—sample transport tube 3—pump controller and 4—sample bottles. (Based on Dick, M.E. 1996. In L.H. Keith (ed.), Principles of Environmental Sampling, 2nd edition, pp. 237-258. American Chemical Society and Dick, E.M. 1994. In B. Markert (ed.), Environmental Sampling for Trace Analysis, pp. 255-278. VCH.)... 

Burke, P.M., S. Hill, N. Iricanin, C. Douglas, P. Essex, and D. Tharin. 2002. Evaluation of preservation methods for nutrient species collected by automatic samplers. Environ. Monit. Assess. 80 149-173. 

No sample/deteriorated sample. 4. Be sure automatic sampler vials... 

Be sure samples are consistent. For fixed volume sample loop, use 2-3 times loop volume to ensure loop is completely filled. Be sure automatic sampler vials contain sufficient sample. Check syringe-type injectors for air. In systems with wash or flushing step, be sure wash solution does not precipitate sample components. 

Fig. 29. Origin of systematic errors in spite of potentially error-free analysis. On-line sampling setups (top) and time trajectories of limiting substrate concentration during sample preparation in the two paradigmatic setups depending on the actual culture density (bottom). Either a filter in bypass loop is used for the preparation of cell-free supernatant (upper part in top insert) or an aliquot of the entire culture is removed using an automatic sampler valve and a sample bus for further inactivation and transport of the samples taken (lower part). Both methods require some finite time for sample transportation from the reactor outlet (at z = 0) to the location where separation of cells from supernatant or inactivation by adding appropriate inactivators (at z = L) takes place. During transport from z = 0 to z = L, the cells do not stop consuming substrate. A low substrate concentration in the reactor (namely s KS) and a maximal specific substrate consumption rate of 3 g g h 1 were assumed in the simulation example to reflect the situation of either a fed-batch or a continuous culture of an industrially relevant organism such as yeast. The actual culture density (in g 1 1) marks some trajectories in the mesh plot. Note that the time scale is in seconds...

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