Sampling duration

Sampling duration The period of time that sampling takes place at a specified sampling rate. 

Sample period begins Sample duration time... 

The detailed composition, referring to classes of compounds, is shown for C6 in Figure 9.3 with and without precolumn hydrogenation. In addition to paraffins, there are olefins—mainly with terminal double bond—and small amounts of alcohols (and aldehydes). The low detection limit of gas chromatography (GC) analysis allows precise determination even of minor compounds and provides exhaustive composition data also for use in kinetic modeling. Because of the short sampling duration of ca. 0.1 s,8 time-resolved selectivity data are obtained. 

Methods Samples were collected for the period of three consecutive days for indoors and outdoors, at each microenvironment. Sampling duration was for 8 h from 10 00 am to 6 00 pm during all the seasons. TVOC levels were measured using a portable data logging Ion Science PhoCheck+ photoionization detector (PID) equipped with 10.6eV ultra-violet lamp4. The sampling instrument was placed... 

Selection of sampling frequency and duration will be determined primarily by the relevant standard, potential sources and resources. The current particulate standard is based on a 24-hour and annual average. Thus, sampling duration should probably not exceed 24 hours. 

The input to receptor models is obtained from ambient sampling, source sampling, and sample analysis. The design of the experiment is important to obtain the most information for least cost. Sampling schedule, sample duration and particle sizing are part of the ambient sampling design. 

Schwartz, G., J. M. Daisey and P. J. Lioy. Effect of sampling duration on the concentration of particulate organics collected on glass fiber filters. Am. Ind. Hyg. Assoc., ... 

Three pump and filter assemblies were operated simultaneously at each location. Sample duration of 51.5 minutes each hour and sample inlet line configuration replicated the Km samplers. Sampling began at 700 hours Pacific Standard Time (PST) and continued over consecutive hours until 1300 PST. 

Sample durations tended to be short, since the field survey team did not have advance knowledge of exposure levels to be encountered and wished to avoid overloading any of the sampling media. In most cases, the exposures measured proved to be relatively low and, as a result of the short sampling times, the loading of each sample was low. Figures 1 and 2 illustrate the... 

Figure 5. Diffusion sampler vs. tube/pump data for sample duration > 60 min...

In another study, personal samples were taken of all workers in the polymerization and flocculation process areas of a plant in the United States, where the highest exposure was expected, and of some employees in other areas of the plant (Kutcher, 1978). The sampling duration was 4-6 h and conditions were considered representative of normal conditions. One outside reactor operator had a TWA of 2.9 ppm ( = 12 0.6-4.3 ppm total duration, 16.7 h) [6.3 1.3-9.3 mg/m ] and another had a TWA of 0.7 ppm [1.5 mg/m ] ( = 12 total duration,... 

The obvious advantages of a passive sampler, as seen in Figure 1, are its simplicity, total portability, and lack of any ancillary equipment needed to collect the sample. The primary drawback is the necessity to collect an integrated sample over an extended period of time. This drawback may not be important if the response time for a biological effect is not significantly shorter than the minimum sampling duration. 

It is essential that samples represent the worker s exposure or the condition to be evaluated. To decide what samples are representative, the person evaluating the exposure must be able to decide where to sample, whom to sample, sample duration, number of samples, and the appropriate sampling period. The choice of sampling location depends upon the type of information needed and may necessitate sampling in the breathing zone of the worker, in the general room air, or directly at the operation. (5)... 

Evaluation of worker exposure requires samples in the breathing zone and in general room air or rest area. To define a potential hazard, check compliance with regulations or obtain data for control purposes, samples would normally be collected in the vicinity of the operation itself. In general, samples are collected in the vicinity of the workers directly exposed and also workers remote from the exposure who voice complaints. Sample duration requires that the sample contain sufficient matter for an accurate analysis and is based on the sensitivity of the analytical procedure and the estimated air concentration, as well as the current threshold limit value for the contaminant. Table 1 contains appropriate sampling duration, sample flow rates and sample volume. 

Location and references Fuel type Average sampling duration Time of measurement Types of measurement (area or personal) Areas of measurement (kitchen, living or outdoors) Size fractions (TSP,PMio or PM2.5) Exposure for adult women (pg/m ) Concentrations (pg/m ) ... 

Location and references Fuel type Average sampling duration Time of measurement... 

Sampling Schedules and Sampling Duration The fourth step is to determine the sampling schedules and duration. Due to the concern about hazards associated with dioxin exposure, the sampling schedule and duration should be continuous during the period in which there is remedial activity on site. This practice will probably continue until information pertaining to the hazards of exposure to dioxin indicate it is not necessary. ... 

The data acquisition, reduction, and storage were controlled by an online computer. The sampling rate was determined by an input variable in the data acquisition software, and was usually set at 30 ms. The numbers of counts (referred to as count rates) of the 16 detectors recorded during the sampling duration were converted into distances between the tracer and the detectors by using previously established calibration. The computer then proceeded to calculate the instantaneous location of the tracer particle. Because the tracer position was usually calculated in real time, only the coordinates of the instantaneous tracer position needed to be stored. The total duration of the experiment depended on the specified data accuracy, but it usually took at least 5 h to ensure significant sampling of the entire bed volume. 

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