INSTRUMENTAL ANALYSIS EXAM
QUESTIONS AND DETAILED ANSWERS.
EXPERT VERIFIED FOR GUARANTEED
PASS.
Purpose of sample preparation - ANS To clean up, concentrate, and make analytes
compatible with the analytical instrument.
Common sample preparation techniques - ANS Dilute and shoot, liquid-liquid extraction
(LLE), and solid-phase extraction (SPE).
Purpose of an internal standard (ISTD) - ANS To ensure quantitative accuracy and
compensate for extraction or injection variability.
Ideal ISTD for non-specific detectors - ANS Structurally similar to analyte, not naturally in
sample, and chromatographically distinct.
Ideal ISTD for MS detectors - ANS Isotopically labeled (D, 13C, or 15N), labeled on fragments,
separated by ≥3 mass units.
Minimum recovery for valid internal standard - ANS At least 50%.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, Purpose of a calibration curve - ANS To relate instrument response to analyte concentration.
Equation for a linear calibration curve - ANS y = mx + b.
Analytical Measured Range (AMR) - ANS The range over which the instrument can accurately
quantify analytes.
LLOQ and ULOQ - ANS Lower and upper limits of quantitation.
Standard Addition Method use - ANS Used when external calibration isn't possible; corrects
for matrix interferences.
When pH = pKa - ANS The compound is 50% ionized and 50% unionized.
Best extraction condition for acidic compounds - ANS Low pH (when unionized).
Best extraction condition for basic compounds - ANS High pH (when unionized).
What pH measures - ANS The acidity or basicity of a solution (0-14 scale).
What pKa measures - ANS A molecule's ability to donate a proton (acid strength).
Acidic compound behavior at pH < pKa - ANS Unionized (protonated).
Basic compound behavior at pH < pKa - ANS Ionized (protonated).
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
QUESTIONS AND DETAILED ANSWERS.
EXPERT VERIFIED FOR GUARANTEED
PASS.
Purpose of sample preparation - ANS To clean up, concentrate, and make analytes
compatible with the analytical instrument.
Common sample preparation techniques - ANS Dilute and shoot, liquid-liquid extraction
(LLE), and solid-phase extraction (SPE).
Purpose of an internal standard (ISTD) - ANS To ensure quantitative accuracy and
compensate for extraction or injection variability.
Ideal ISTD for non-specific detectors - ANS Structurally similar to analyte, not naturally in
sample, and chromatographically distinct.
Ideal ISTD for MS detectors - ANS Isotopically labeled (D, 13C, or 15N), labeled on fragments,
separated by ≥3 mass units.
Minimum recovery for valid internal standard - ANS At least 50%.
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
, Purpose of a calibration curve - ANS To relate instrument response to analyte concentration.
Equation for a linear calibration curve - ANS y = mx + b.
Analytical Measured Range (AMR) - ANS The range over which the instrument can accurately
quantify analytes.
LLOQ and ULOQ - ANS Lower and upper limits of quantitation.
Standard Addition Method use - ANS Used when external calibration isn't possible; corrects
for matrix interferences.
When pH = pKa - ANS The compound is 50% ionized and 50% unionized.
Best extraction condition for acidic compounds - ANS Low pH (when unionized).
Best extraction condition for basic compounds - ANS High pH (when unionized).
What pH measures - ANS The acidity or basicity of a solution (0-14 scale).
What pKa measures - ANS A molecule's ability to donate a proton (acid strength).
Acidic compound behavior at pH < pKa - ANS Unionized (protonated).
Basic compound behavior at pH < pKa - ANS Ionized (protonated).
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED
