Lecture 10: Atomic Spectroscopy & Urinalysis

flashcards covering urine composition, sample cleanup, calibration, Beer-Lambert law, standard addition, internal standards, spectroscopy methods (AAS, AES, ICP, MP-AES), interferences, and final considerations from the renal case lecture notes.

What does the acronym ICP stand for in atomic spectroscopy?

Inductively coupled plasma.

Name two methods used for measuring simple ions as described by Miller et al.

Ion-selective electrode and glass electrode for metals.

What is the purpose of sample cleanup using SPE cartridges in atomic spectroscopy?

Remove interfering matrix components and concentrate the analyte.

According to the notes, what is the approximate water content of urine?

About 95%.

What is the typical pH range of urine as given in the notes?

4.6 to 8.0.

What is the daily excretion range of uric acid mentioned in the notes?

250–750 mg/day (assuming ~2.5 L/day).

Name three constituents of urine listed in the notes.

Urea, Creatinine, Urobilin.

What is the main purpose of standard addition in spectroscopy?

Counter matrix effects in complex samples by adding known aliquots of a standard.

In standard addition, what is the formula for the unknown concentration cx given added standard volume Vs,0 and standard concentration cs, and sample volume Vx?

cx = (Vs,0 × cs) / Vx.

What is the purpose of using an internal standard in calibration?

To compensate for sampling/injection inconsistencies by using a fixed quantity of a similar analyte.

Name two main categories of atomic spectroscopy techniques.

Atomic Absorption Spectroscopy (AAS) and Atomic Emission Spectroscopy (AES).

Briefly state the principle of Atomic Absorption Spectroscopy (AAS).

Electronic excitation of volatilised atoms and measurement of absorbed light to quantify elements.

What is Microwave Plasma-Atomic Emission Spectroscopy (MP-AES) and a key advantage over FAAS?

AAS using microwave plasma; advantages include unattended operation, no flame/gas handling, and improved sensitivity and linear range.

Which elements are commonly detected by flame photometry according to the notes?

Lithium (Li), Sodium (Na), Potassium (K), Calcium (Ca).

What emission line is characteristic for sodium in flame spectroscopy?

589 nm (the Na D-line).

What is the role of the deuterium (D2) lamp in AAS instrumentation?

Provides a background reference signal for background correction.

Why is background correction important in AAS?

To remove or account for non-sample background signals in the flame/optical path.

What is the L’vov platform used for in graphite furnace AAS?

A shelf inside the graphite tube to hold the sample and enhance sensitivity by concentrating the analyte.

Name two common interferences encountered in AAS as listed in the notes.

Oxides (e.g., from refractory materials) and silicates (e.g., alumina, aluminates).

What additive can mitigate phosphate interference by preferential binding, as noted?

Lanthanum (La).

State the Beer-Lambert law and what the symbol e represents.

A = ε c l; ε is the molar extinction (molar absorptivity) coefficient.

What is the purpose of continuum source correction in AAS?

To correct for background absorbance due to the flame and instrument, removing non-specific signal.

What does ICP stand for in ICP-AES/ICP-OES?

Inductively Coupled Plasma (argon-based plasma used as the excitation source).

Give two examples of alumino-silicate interferents mentioned in the notes.

Kaolin and phyllosilicates (clay minerals) that can interfere with measurements.

Name a specialized atomisation technique used for metalloids like arsenic (As) and selenium (Se).

Hydride generation.

What technique is used for mercury that relies on a cold vapour approach?

Cold vapour atomic absorption (CVAAS) for mercury.

Which color is associated with lithium (Li) in flame test colors listed in the notes?

Red.

What is the sodium emission line color and its primary wavelength mentioned?

Yellow emission around 589 nm (Na D-line).