During an autopsy and subsequent toxicology reports, it is discovered that a man died from arsenic poisoning. when investigating the crime scene, a bottle of gatorade was discovered next to the dead body. what type of lab technique will need to be performed first to see if there is any arsenic mixed in with the gatorade?

Spectrophotometry is a laboratory technique that can be performed first to check if there is presence of arsenic mixed in with Gatorade. In spectrophotometry, arsenic concentration will be measure in a specific solution by calculating the amount of light absorbed by inorganic arsenic.

Various analytical reagents are used such as molybdate reagent and variamine blue as a chromogenic reagent where a violet colored indicates presence of arsenic. 

Furthermore, new analytical reagents has been development and proposed like vanillin-2- amino nicotinic acid (VANA) and 2, 4-Dihydroxy benzophenone-2-amino thiophenol (BPBT). These are used for direct non-extractive spectrophotometric determination of arsenic. The reagent reacts with arsenic in acidic medium to form light greenish yellow colored.

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west