Final Exam Drug ID Lab

Calibration of Pipettes — What was measured? How so?

The calibration of pipettes involves measuring the accuracy and precision of the volume dispensed by the pipette. This is typically done by comparing the volume dispensed to a known standard using a balance to weigh the dispensed liquid.

Calibration of Pipettes — Why is density important?

Density is important in pipette calibration because it affects the weight of the dispensed liquid, which is used to determine the accuracy of the volume measurement. Accurate volume dispensation relies on knowing the density to convert weight to volume accurately.

Calibration of Pipettes — What is the difference between accuracy and precision?

Accuracy refers to how close a measured value is to the true value, while precision refers to the consistency of repeated measurements, regardless of their closeness to the true value.

Presumptive Drug Test — What tests did we use?

We used the Marquis reagent, Mandelin reagent, Scott reagent, and Simon reagent.

Presumptive Drug Test — What did they test for?

• Marquis — alkaloids (amphetamine-type drugs)

• Mandelin — alkaloids

• Scott — cocaine

• Simon — amphetamine vs meth

What is the difference between presumptive and confirmatory?

Presumptive tests are quick and preliminary, needing further confirmation. Confirmatory tests are definitive and highly accurate, used to validate presumptive results. They show structural information.

What are the advantages of presumptive tests?

They are simple and easy to use.

What is the main use of the microcrystalline test?

It is a quick, effective method for the presumptive identification of specific compounds, often used in forensic and chemical laboratories.

What does polarized light do?

It enhances crystal visibility and differentiates crystals.

What are the two phases?

• reaction phase — ensures the interaction between the substance and reagent to create a chemical environment suitable for crystal formation

• crystallization phase — produces characteristic crystals, whose morphology and optical properties enable identification of the substance

What does TLC stand for?

thin layer chromatography

What is chromatography?

It is a tool for separating, identifying, and analyzing complex mixtures.

Rf value

distance traveled by the substance/distance traveled by the solvent front

How did we visualize the chromatogram?

UV light

What is polarities role in chromatography?

it influences how substances interact with the stationary and mobile phases, ultimately determining the separation of components in a mixture.

What is spectroscopy?

It is a scientific technique used to study the interaction between matter and electromagnetic radiation

What are the different sections of the electromagnetic spectrum?

Radio waves, microwaves, IR, visible light, UV, x-rays, and gamma rays

what is beer’s law?

• A=Ecl

• relates the absorption of light by a substance to its concentration in a solution

What is the purpose of a calibration curve? How do we construct them?

To determine the concentration of an unknown sample by comparing its measured response to the curve.

Where do chemical bonds absorb electromagnetic waves?

IR region

What is the layout of the Michelson Interferometer? How does it work?

There is a light source, a beam splitter, and mirrors. It works by splitting light into two beams, reflecting them back, recombining them, and observing the interference pattern. This pattern changes with path differences and can be used for precise measurements.

What are the different parts of the GC-MS?

• injection port

• column

• carrier gas

• oven

• detector

• ion source

• mass analyzer

• detector

• data system

What happens to our sample starting from injection and ending at MS detector?

• injection

• separation

• transfer

• ionization

• analysis

• detection

• interpretation

What is our ionization source?

electron impact ionization

What is m/z?

mass over charge ratio

What is the difference between Split and splitless mode?

• split mode ideal for higher concentrations

• splitless mode ideal for very low concentrations