clin chem exam 1 quiz questions

A molecule is said to fluoresce when it absorbs light at one wavelength and emits light of a lower energy. a shorter wavelength. a higher energy. the same wavelength.

a lower energy

10. The most sensitive kind of detector used in GLC methods is a. thermal conductivity b. flame ionization c. electron capture d. spectrophotometer set at 206 nm

c. electron capture

1. You have a fluorescence method which uses both 570 nm and 445 nm. When you purchase the fluorometer to do this assay, which one of these is going to be placed in the excitation wavelength filter position? a. 445 nm c. neither one can go there b. 570 nm d. not enough information provided

a. 445 nm

The type of separation mechanism for chromatography that involves, as one example, use of immunologic principles is _____ chromatography. a. ion exchange * B. affinity C. partition D. adsorption

affinity

Which one of the following components is found only in a fluorometer used to make measurements of emitted fluorescent light as opposed to in a spectrophotometer used to make measurements of absorbed/transmitted light? a. monochromator b. cuvets as sample holders c. an excitation source d. detector

an excitation source

1. In fluorescence polarization immunoassay methods, the fluorophore tag will always be attached to the a. antibody b. reagent ligand c. patient ligand

b. reagent ligand

1. A non-enzymatic chemical reaction which emits light is called a. fluorescence c. phosphorescence b. bioluminescence d. chemiluminescence

d. chemiluminescence

Because of the ability to identify and quantify proteins in a complex mixture, mass spectrometry combined with separation methods is an excellent analytical tool used specifically in the field of: a. genomic research. B. inborn errors of metabolism. C. trace metal analysis. * D. proteomics.

proteomics

In the isolation of nucleic acids from blood samples, a step is typically performed to separate large molecules, such as proteins and nucleic acids, from smaller molecules such as salts. Which type of separation mechanism would best be suited for this task? a. ion exchange B. Affinity C. Partition *D. Size-exclusion

size exclusion

The soft ionization technique that uses a UV-absorbing compound upon which the analyte of interest is placed and eventually vaporized into a plume of ions directed into the mass analyzer is: a. atmospheric pressure photoionization. B. electrospray ionization. * C. matrix-assisted laser desorption ionization. D. inductively coupled plasma ionization.

matrix-assisted laser desorption ionization. - MALDI

Which one of the following optical techniques is not considered an emission technique? Phosphorimetry Nephelometry Luminometry Fluorometry

nephelometry

Which one of the following improvements could be made to increase the chromatographic (separation) efficiency of a poorly resolved HPLC separation a. Using a shorter column B. Changing the composition of the mobile phase * C. Using smaller particles in the stationary phase D. Increasing the dead volume

. Using smaller particles in the stationary phase

In spectrophotometric determinations, which of the following is the formula for calculating the absorbance of a solution? a. (Molar absorptivity × length of light path)/concentration in mol/L b. (Molar absorptivity × concentration in g/dL)/length of light path c. (Molar absorptivity × length of light path) × concentration in mol/L d. (Length of light path × concentration in g/dL)/molar absorptivity

(Molar absorptivity × length of light path) × concentration in mol/L

Some analytes must be derivatized to increase their column retention or detectability. Derivatization means a. altering the chemical structure of the analyte to an isomeric form to increase detection and specificity. B.adding fluorescent labels or combining the analyte with chiral reagents or other chemicals to increase detectability. C.removing dissolved gases in the solvent to produce a clear chromatogram. D.using multiple detectors to assist in identification.

. adding fluorescent labels or combining the analyte with chiral reagents or other chemicals to increase detectability.

Which one of the following wavelengths is within the "near" ultraviolet region of the electromagnetic spectrum? 320 nm 450 nm 540 nm 690 nm

320 nm

Which one of the following would be a limitation in a nephelometric measurement that might produce faulty values? a. Excess antigen in the antigen/antibody reaction b. Too much fluorophore in the analyte/fluorescing compound mixture c. Incorrect filter used to isolate a specific wavelength d. Absorption by a closely related atomic species

Excess antigen in the antigen/antibody reaction

When selecting a photometric technique that is more sensitive to a low concentration of analyte, a laboratory director compares absorbance measuring devices against those that measure fluorescence intensity. Which technique is considered more sensitive in its measurements and why? a. Absorbance measurements are more sensitive because of the ability of the monochromator to isolate very specific parts of the spectrum. b. Fluorescence intensity measurements are more sensitive because the fluorophores used are very specific to the analytes they bind to and will bind to small analytes easily. c. Fluorescence intensity measurements are more sensitive because of the use of intense light sources, signal filtering, and sensitive light emission photometers. d. Absorbance measurements are more sensitive because the flame can break down complex compounds into elements that are specifically measured.

Fluorescence intensity measurements are more sensitive because of the use of intense light sources, signal filtering, and sensitive light emission photometers.

In regard to mass spectrometry, what is a molecular ion? a. It is a component of a compound in solution. B. It is the sum of all ions produced displayed as a function of time. *C. It is the unfragmented ion of the original molecule being studied. D. It is the ion with the highest abundance in the mass spectrum of a compound.

It is the unfragmented ion of the original molecule being studied.

Which component of a generic spectrophotometer isolates radiant energy of a specific wavelength (spectral isolation) and excludes that of other wavelengths? a. Monochromator b. Entrance slit c. Cuvet d. Light source

Monochromator

What type of mass spectrometer uses radio frequency-generated fields to confine ions in three dimensions?

Quadrupole ion trapping-mass spectrometer

1. In FPIA, a small ligand attached to a fluorophore tracer will rotate than when it is bound by an antibody, and this results in polarized light reaching the detector. a. faster...... less c. more slowly....less b. faster.....more d. more slowly....more

a. faster....less

10. When a sample is tested by GLC, a peak shows a retention time of 4.6 minutes. If the gas flow rate becomes more rapid between the first and second run, which of the following things would you expect to see happen when that sample is repeated in the second run? a. peak comes out of the column earlier than 4.6 minutes b. peak comes out of the column later than 4.6 minutes c. unchanged retention time

a. peak comes out of the column earlier than 4.6 min

1. Which part of a GLC has to be at a higher temperature than the patient sample? CHOOSE ALL CORRECT a. sample syringe c. column oven e. readout b. column d. sample injector

b. column c. column oven d. sample injector

In a mass spectrometer, the ion with the highest abundance in the mass spectrum that is assigned a relative abundance of 100% is referred to as the: a. base peak. B. ion trap. C. ionic chromatogram. D. time-of-flight ion.

base peak

10. The sample with the lowest concentration of these five separated molecules is because _. a. #1..... earliest retention time c. #1.....smallest peak height/width b. #5..... earliest retention time d. #3.... smallest peak width

c. #1... smallest peak height/width

10. The part of a GLC setup which is actually doing the separation of the molecules in a sample mixture is a. inert glass beads c. silicone oil b. nitrogen gas d. nylon column

c. silicone oil

You are preparing placental tissue for separation and isolation of a specific enzyme. The enzyme has a negative charge, so you want to use chromatography to perform your task. Which one of the following chromatographic separation mechanisms would be most useful? a. Ion-exchange B. Partition C. Affinity D. Adsorption

ion-exchange

1. You perform a drug assay using fluorescence in the morning and again in the afternoon. The morning run (calibrators, controls, patients) all seem to be fine, but the afternoon run shows significantly lower fluorescence signal values for all samples than before. An explanation of this could be a. contaminated calibrator c. hemolytic interference b. pH change in the buffer used - quenching d. ionization of the drug in the patient sample

pH change in the buffer used

An example of a clinical application of an HPLC coupled to a tandem mass spectrometer would be: a. determining the presence of trace elements in blood. *B. screening and confirming the presence of inborn errors of metabolism. C. identifying specific protein. D. quantifying drugs of abuse.

screening and confirming the presence of inborn errors of metabolism.

In which one of the following mass spectrometers does the fragmentation of ions take place after they have been separated by their m/z value in a first stage

tandem mass spec

In a fluorometric measurement, the difference between the maximum wavelength of the excitation light and the maximum wavelength of the emitted fluorescence light is a constant referred to as: Beer law. chemiluminescence. polarization. the Stokes shift.

the Stokes shift.

A type of detector used in GC that is universal in its detection of compounds but has low sensitivity compared with other detectors is a(n) _____ detector. a.flame ionization * B. thermal conductance C. electron capture D. photoionization

thermal conductance