A “holding time” is the elapsed amount of time from the point of collection to the moment of preparation or analysis.If samples are analyzed beyond an analytical holding time, the data will be qualified on the analytical report and may not be usable for compliance.
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Contents
What is holding time in communication?
[′hōl·diŋ ‚tīm] (communications) Period of time a trunk or circuit is in use on a call, including operator’s time in connecting and subscriber’s or user’s conversation time.
What is maximum holding time?
Maximum holding time means the greatest number of minutes, hours, or days that a sample may be kept between sampling and the beginning of analysis and still be considered a valid sample for compliance testing.
What is the hold time for pH?
15 minutes
Methods 9040 and 9045 for pH both say that samples should be analyzed as soon as possible. 40 CFR 136 Table II defines the maximum holding time for Hydrogen ion (pH) as 15 minutes.
What is dwell time in wireless communication?
The dwell time, also denoted as cell residence time or mobile sojourn time, is a random variable that describes the amount of time a mobile spends in a radio cell. Therefore, the dwell time depends on the following parameters: veloc- ity of the subscriber, cell size, cell shape, and the traversed path.
What is holding time in microbiology?
Holding time and temperature can have a significant impact on the density of microbiological indicators at the time of sample analysis (4, 5, 7). Recommendations for E. coli holding times range from 8 h (2, 3, 9) to 24 h (8), and holding temperatures below 10°C are generally considered acceptable (2, 3, 8, 9).
What is the holding time for TSS?
7 days
A very common pollutant on many NPDES stormwater permits, TSS (total suspended solids), has a holding time of 7 days. Chemical oxygen demand, another common pollutant parameter has a holding time of 28 days.
What is hold time for TSS samples?
within 7 days
Many scientific laboratories follow, as standard practice, a relatively short maximum holding time (within 7 days) for the analysis of total suspended solids (TSS) in environmental water samples.
What is the holding time for nitrate?
Aqueous Sample Reference Guide
| Inorganics | ||
|---|---|---|
| Analyses | Methods | Holding Time |
| MBAS | 425.1, SM5540C | 48 Hours |
| Nitrate | 300.0, 353.2, SM4500NO3 -F | 48 Hours |
| Nitrate/Nitrite | 353.2, SM4500NO3 -F | 28 Days |
What is the holding time if the water sample is not preserved?
Holding times are generally very short – 8 hours for source water compliance samples, 30 hours for drinking water samples, 48 hours for coliphage samples.
How do you preserve a sample?
Preservation methods are limited to pH control, chemical addition, amber or opaque bottles, filtration, refrigeration, and freezing. To minimize the potential for volatilization or biodegradation between sampling and analysis, keep the sample as cool as possible without freezing.
What is dwell time?
Dwell time is the length of time a person spends looking at a webpage after they’ve clicked a link on a SERP page, but before clicking back to the SERP results. You’ve done this lots of times, most likely. It’s that brief moment when you evaluate the webpage you just clicked to visit.
What is dwell time electronics?
The “dwell time” is the length of time that the distributor points are closed, applying power to the spark coil.
What is dwell time in power electronics?
The time period for which a call is maintained in a cellular region is called dwell time. There is some basic factor that influences the dwell time are : propagation. Interference. The distance between the subscriber and the base station.
Why are holding times important?
Required holding times ensure that the sample is analyzed for the requested parameter prior to any bio-degradation, oxidation, precipitation, sorption, volatilization, and other physical and chemical processes that may occur that can affect the integrity of the sample.
How do you preserve a wastewater sample?
Preservation is accomplished by refrigerating or by adding nitric acid. Dissolved gases (oxygen, carbon dioxide, hydrogen sulfide), pH, and temperature can change within minutes after collection. There are no practical methods of preserving these. Analyses for them should be performed at the collection site.
How do you collect a water sample for microbiological analysis?
Hold the closed bottle near its base and plunge it below the surface. Remove the top and turn the bottle until its neck points slightly upward and mouth is directed toward the current. If there is no current, create one by pushing the bottle forward away from the hand. Replace cap before pulling the sample out.
How do you preserve cod samples?
Samples are iced or refrigerated and kept at 4°±2°C from time of collection until analysis. Preserved samples must be analyzed within 28 days of collection.
How long can a water sample be held before it is analyzed?
Typically, water samples have a maximum holding time that ranges anywhere from six hours to six months. Some attributes, however, require immediate analysis, such as the following: Dissolved oxygen.
How do you preserve water samples for heavy metal analysis?
HNO3 acid is required to preserve the water samples to minimize metal cation precipitation and adsorption onto the sample. Adding Concentrated acid is required mostly for microbial deactivated and acting as perservative and also minimize metal precipition but hydrochloric acid is the preferred solvent for this purpose.
How long is a water test good for?
Q. How often should I have my well tested? Many state and federal authorities recommend having your water tested annually for coliform bacteria and nitrates. Other contaminants should be tested for at least once every five to ten years.