GC-MS Analysis of Wastewater Samples

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What is the primary analytical technique used to identify organic compounds A and B in the wastewater sample?

High-Performance Liquid Chromatography (HPLC)
Atomic Absorption Spectroscopy (AAS)
Gas Chromatography Mass Spectrometry (GC-MS) (correct)
Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)

Nitrogen (N2) is used as a carrier gas in the GC-MS system, which always results in high sensitivity regardless of linear velocity.

False (B)

In the GC-MS analysis, what data is presented on the chromatogram to help identify the compounds?

Retention time and abundance

The peaks identified in the mass spectrum are cross-referenced with known and pure compounds for a process known as ______ analysis.

qualitative Signup and view all the answers

If compound A has a lower retention time and a broader peak width compared to compound B, what does this suggest?

Compound A has a lower abundance and elutes slower with poor resolution. (A) Signup and view all the answers

What specific type of information from the mass spectrum is used to cross-reference and confirm the identity of a compound?

The mass-to-charge ratio of the fragments (A) Signup and view all the answers

Describe one way the mass spectrum produced by the GC-MS system is used to identify compounds within the wastewater sample.

By comparing the mass spectrum of each component to the mass spectrum of known and pure compounds. Signup and view all the answers

A higher abundance of a compound in the chromatogram always indicates a higher concentration of that compound in the original sample, regardless of other factors.

False (B) Signup and view all the answers

An ICP-OES identifies components within a sample by:

Measuring the light emitted from excited atoms or ions. (A) Signup and view all the answers

Non-polar columns in GC-MS are best used to extract and identify polar compounds with higher accuracy.

False (B) Signup and view all the answers

How does the molecular composition of a compound affect its retention time in GC-MS?

More complex structures tend to have longer retention times. Signup and view all the answers

In GC-MS, different _________ can be applied to assist in compound separation based on the intended result.

columns Signup and view all the answers

Match the following concepts with their descriptions related to analytical instrumentation:

ICP-OES = Uses emitted light from excited atoms to identify elements. GC-MS = Separates compounds based on volatility and identifies them by mass. Retention time = Time taken for a compound to elute from a chromatography column. Carrier gas = Mobile phase in GC that affects separation quality. Signup and view all the answers

Which factor affects the quality of results in a GC-MS system, in relation to the mobile phase?

The mobile phase flow velocity. (B) Signup and view all the answers

The spectrum from an ICP-OES provides information about the mass-to-charge ratio of compounds.

False (B) Signup and view all the answers

What data from ICP-OES is used to identify the presence of a compound in a sample?

Peaks present on a spectrum over wavelengths Signup and view all the answers

If the absorbance measured during ICP-OES is excessively high, what is the most likely cause?

Spectral interference from other substances absorbing at the same wavelength. (D) Signup and view all the answers

Matrix matching involves using different solvents for standards, blanks, and samples to minimize chemical interference.

False (B) Signup and view all the answers

What could cause the fronting peak symmetry observed for Compound A?

Injecting too much sample into the system. (A) Signup and view all the answers

What is the purpose of silylation in GC-MS?

To improve volatility and detectability Signup and view all the answers

In GC-MS, the choice of column is important based on its ______.

polarity Signup and view all the answers

A molecular ion peak with an m/z value of 231 guarantees the molecular weight of the compound is exactly 231 g/mol without high-resolution confirmation.

False (B) Signup and view all the answers

What is the main benefit of using ICP-OES compared to other spectroscopy methods?

Faster results with high throughput (B) Signup and view all the answers

In mass spectrometry, what term describes the most intense peak in the spectrum, and why is it important?

base peak Signup and view all the answers

When using external calibration methods, and the calibration curve follows the formula y = mx, it indicates a direct proportionality between the signal (y) and the ______.

concentration Signup and view all the answers

Which of the following factors are crucial to consider when preparing samples to improve quantitative analysis of Cu^2+^?

Chemical and spectral interference (C) Signup and view all the answers

In the Cu^2+^ standard solution calculations, what type of dilution is used to create the 15ppm, 10ppm, and 5ppm standards from a 50ppm stock?

Direct dilution (B) Signup and view all the answers

Based on the information provided, what is the calculated concentration of the unknown Cu^2+^ solution before dilution?

25.22 ppm (D) Signup and view all the answers

Why is serial dilution preferred over direct dilution when preparing a 1ppm standard solution from a 10ppm solution?

Serial dilution is more accurate for low concentrations (B) Signup and view all the answers

Match the following descriptions with the appropriate analytical technique:

GC-MS = Identification and quantification of volatile organic compounds. ICP-OES = Fast, high-throughput quantitative analysis of elements using plasma. Matrix Matching = Minimization of chemical interference using standards/blanks. Signup and view all the answers

In the ICP-OES calibration curve described, what do the y-axis and x-axis represent, respectively?

absorbance, concentration Signup and view all the answers

Match the following dilution processes with their corresponding calculation formulas:

Direct Dilution = $M_1V_1 = M_2V_2$ Serial Dilution (to find final volume) = $V_2 = \frac{(M_1)(V_1)}{M_2}$ Signup and view all the answers

Chromatograph

A graph showing the separation of different compounds based on their properties.

Matrix Matching

A method to minimize errors in quantitative analysis by matching the standard's and sample's environment.