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There are several gunpowder contaminants such as the fertilizer, detergent, match head, even soil and cigarettes. They contain nitrates which gives similar result to gunpowder residues when treated with Diphenylamine (DPA) Reagent.However, their reaction differ from gunpowder nitrates from the characteristics of the specks as well as the distribution of the specks. Usually a gunpowder contaminants will show a smear of blue color .
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What is the difference between reagent blank and sample blank?
Reagent Blank : Take reagent and add deionised water (in place of sample to be tested). Now measure the OD at specific wavelength --> this OD is your reagent blank. Substract this OD from your test result (with sample) to avoid any false +ve effect due to colour of reagents itself.Sample Blank : Take sample and measure the OD without adding reagents --> this OD is your sample blank. Substract this OD from your test result to avoid any false +ve effect due to colour and turbidity of sample itself. As it is the fact that colour and turbidity of each sample would vary from one to another.So now it is clear that Reagent blank is used to avoid bias due to colour of reagents and Sample blank is used to avoid bias due to sample itself.
Why does the oxidase reagent need to be fresh?
The oxidase reagent needs to be fresh because it contains the enzyme cytochrome c oxidase, which can degrade over time, leading to false-negative results if it is not active. Using fresh reagent ensures the accuracy of the test results.
If too much material is removed from a reagent container the excess can be safely returned to the container if it has not touched anything?
Returning excess material to the original container can introduce possible contamination and compromise the stock solution. It's best practice to avoid returning unused reagent to its original container to ensure accuracy and purity of the stock solution for future experiments.
What factors may cause false negative color reactions?
False negative color reactions can occur due to several factors, including insufficient sample concentration, improper reagent handling or storage, and interference from contaminants or substances within the sample. Additionally, environmental conditions such as temperature and pH can affect the chemical reactions needed for color development. Lastly, expired or degraded reagents can also lead to inaccurate results.
Could an error in a pregnancy test result in a false positive or false negative outcome"?
Yes, an error in a pregnancy test could lead to a false positive or false negative result.
Can folliculitis cause a false positive hsv2 result?
No, folliculitis will note cause a false positive HSV2 result.
If too much material is removed from a reagent container the excess can be safely returned to the container if it has not touched anything.?
False. It is impossible not to have touched anything.
If too much material is removed from a reagent container the excess can be safely returned to the container if it has touched anything?
False. It is impossible not to have touched anything.
Is too much material is removed from a reagent container the excess can be safely returned to the container if it has not touched anything?
False. It is impossible not to have touched anything.
Why oxidase reagent need to be fresh?
Oxidase reagent needs to be fresh because it is sensitive to degradation and can lose its reactivity over time. When the reagent is old or improperly stored, it may not accurately detect the presence of cytochrome oxidase in microbial cultures, leading to false-negative results. Fresh reagents ensure reliable and consistent performance in biochemical tests.
When did the Chinese invent the gunpowder?
The Chinese invented gunpowder in 850 B.C.
Is it true or false the ability of a measurement to be reproduced with the same result is a sign of accuracy?
false
