Question 1

Which of the following is considered the most powerful analytical tool in the laboratory analysis of hemoglobin variants?

Accepted Answer

A)  electrophoresis
B)  high-pressure liquid chromatography
C)  radial immunodiffusion
D)  densitometryE) All of the above
F) A) and B) B

Question 2

Normal hemoglobin fractions seen in HPLC include all but which of the following?

Accepted Answer

A)  Hb A
B)  Hb A2
C)  Hb C
D)  Hb FE) B) and D)
F) A) and B)

Question 3

Hb F may be acetylated in vivo.What is the effect of acetylated Hb F on the measurement of total Hb F (acetylated and non-acetylated)  by HPLC?

Accepted Answer

A)  The peak produced by Hb F will be much larger in the presence of the acetylated form because of the increased absorptivity of the acetyl group, resulting in an overestimation of total Hb F levels.
B)  The acetylated form of Hb F cannot be detected by HPLC systems, causing the level of total Hb F to be underestimated.
C)  The acetylated form of Hb F will have a different retention time from the non-acetylated form, resulting in the need to sum both forms to determine the total Hb F level.
D)  The presence of the acetylated form of Hb F will produce baseline drift, causing the analysis of total Hb F to be unreliable.E) C) and D)
F) A) and B)

Question 4

Standard hemoglobin electrophoresis on cellulose acetate at pH 8.6 is utilized in some laboratories for the evaluation of hemoglobins.In many cases, this is followed by hemoglobin electrophoresis on the same patient sample, using citrate agar at pH 6.2.What is the purpose of this second electrophoretic analysis?

Accepted Answer

A)  to confirm the results of the electrophoresis in the cellulose acetate (alkaline)  system
B)  to aid in the identification of hemoglobins that co-migrate in the cellulose acetate (alkaline)  system
C)  to replace the need for chromatographic analysis
D)  to give the technologist confidence that the initial results are correct, since the second technique will produce identical results as the first techniqueE) A) and B)
F) A) and C)

Question 5

Many HPLC systems utilize "windows" to aid in the interpretation of hemoglobin chromatographic analyses.Which of the following best describes chromatographic windows?

Accepted Answer

A)  time intervals associated with changes in mobile phase ionic strength during gradient analysis
B)  time intervals associated with detector measurement at two different wavelengths
C)  time intervals during which specific hemoglobin fractions are expected to elute
D)  time interval between the analysis of two different samples during which the chromatograph re-equilibratesE) None of the above
F) A) and B)

Question 6

The Singer 1-minute denaturation test and the Betke 2-minute alkali denaturation test is useful for measuring Hb ________ and is based on this hemoglobin's ________.

Accepted Answer

A)  A, resistance to alkaline solutions
B)  A, denaturation by alkaline solutions
C)  F, resistance to alkaline solutions
D)  F, denaturation by alkaline solutionsE) B) and C)
F) All of the above

Question 7

Hb A2 is often falsely elevated in the presence of __________ and falsely reduced in the presence of ________.

Accepted Answer

A)  Hb S, Hb D-Punjab
B)  Hb F, Hb D-Punjab
C)  Hb S, Hb C
D)  Hb F, Hb CE) B) and D)
F) B) and C)

Question 8

Hb F is the major hemoglobin fraction present in neonates and is found elevated in various hematologic conditions.Which of the following problems may be encountered in the HPLC analysis of Hb F when it is greatly elevated?

Accepted Answer

A)  The measured retention time may fall outside the Hb F window, causing the peak to be labeled as "unknown."
B)  Hb F will be measured as part of the background and produce no discernable chromatographic peak
C)  Hb F will crystallize and block flow through the chromatographic column.
D)  Hb F will break into fragments, producing multiple peaks for detection.E) B) and C)
F) C) and D) A

Question 9

Quantification of Hb A2 following separation by cation-exchange HPLC produced a result of 15% in an Hb AA patient.Which of the following describes a concern the technologist should have regarding this result?

Accepted Answer

A)  There may be other hemoglobin variants co-eluting with Hb A2, causing the Hb A2 result to be falsely elevated.
B)  The low Hb A2 result may be falsely decreased because of an integration error caused by a rising baseline.
C)  Quantification of Hb A2 by HPLC is no longer recognized by CAP because of significant intralaboratory variation in Hb A2 measurements.
D)  Glycation of Hb A2 may cause its concentration to vary significantly, based on the extent to which Hb A2 is glycated.E) B) and C)
F) A) and C)

Question 10

Your lab uses the BioRad HPLC system for hemoglobin analysis.As you set up for the analysis, you power up the instrument to allow it to reach operational temperature and prepare the mobile phase buffer.When the instrument and mobile phase are ready, you begin pumping the mobile phase through the system to allow the instrument to equilibrate.You next inject your calibrator.The resulting chromatogram shows nothing but a flat baseline.You inject a larger volume of calibrator and get the same result.Which of the following would explain these results?

Accepted Answer

A)  The column heater is not set too high.
B)  The detector is set at the wrong wavelength.
C)  Chromatographic windows are not assigned properly.
D)  The mobile phase was not prepared to the correct ionic strength.E) None of the above
F) All of the above

Question 11

Which of the following steps are performed automatically by HPLC systems used in hemoglobin analysis?

Accepted Answer

A)  dilution of the blood sample
B)  hemolysis of the blood sample
C)  injection of the blood sample in the HPLC system
D)  all of the above are performed by automated HPLC systemsE) A) and C)
F) All of the above

Question 12

Suppose HPLC results suggest Hb S trait.Why should this be confirmed with the sickle solubility test?

Accepted Answer

A)  Retention characteristics of hemoglobins vary significantly between chromatographic runs, requiring this confirmation step.
B)  With chromatography, there is always the possibility of unknown hemoglobins co-eluting with the suspected hemoglobin.
C)  The use of chromatographic windows has been associated with a high degree of imprecision.
D)  The sickle solubility test is the only technique available to quantify Hb S.E) A) and B)
F) None of the above

Question 13

Your laboratory provides preliminary identification and confirmation of hemoglobin fractions.Suppose your laboratory initially identified a hemoglobin fraction by cation-exchange HPLC.Which of the following techniques should be selected to confirm the presence of the hemoglobin fraction?

Accepted Answer

A)  cation-exchange HPLC on a different HPLC instrument
B)  anion-exchange HPLC
C)  column chromatography
D)  isoelectric focusingE) B) and C)
F) A) and D)

Question 14

Given that Hb Barts elutes first and Hb C elutes last using cation exchange HPLC, which of the following statements most accurately describes the charge of these hemoglobins under chromatographic conditions?

Accepted Answer

A)  Hb C is more positively charged than Hb Barts.
B)  Hb Barts is more positively charged than Hb C.
C)  Hb C has no positive charge, whereas Hb Barts has a positive charge,
D)  Hb C is more negatively charged than Hb BartsE) All of the above
F) C) and D)

Question 15

Bilirubin is a common interference encountered in the HPLC analysis of hemoglobins, because patients with high levels of bilirubin will show a sharp peak in the same general area as:

Accepted Answer

A)  Hb Barts
B)  Hb D-Punjab
C)  Hb G-Philadelphia
D)  Hb FE) B) and C)
F) A) and C)

Question 16

Isoelectric focusing (IEF)  may be utilized to investigate unresolved HPLC hemoglobin results.What advantage of this technique makes it useful in this situation?

Accepted Answer

A)  IEF is a technique that is readily adaptable to automation, resulting in a quick and simple method to resolve questionable HPLC hemoglobin results.
B)  IEF is a technique that does not depend on the charge of the hemoglobin fractions, providing a method that complements HPLC analysis of hemoglobin fractions.
C)  IEF results in the formation of discrete sharp bands, allowing clear separation of the various hemoglobins present in the patient sample.
D)  IEF provides an enhanced method of detection that may allow the technologist to see fractions not detected by HPLC.E) A) and D)
F) A) and C)

Question 17

Consider the separation of Hb 1, Hb 2, and Hb 3 by cation-exchange HPLC.The initial mobile phase pH causes Hb 1 to have the greatest positive charge, Hb 2 to have minimal positive charge, and Hb 3 to be neutral.Predict the order of elution from the stationary phase as the chromatographic run continues from the initial mobile phase to mobile phases with increasing concentrations of cations.(first to elute to last to elute)

Accepted Answer

A)  Hb 1, Hb 2, Hb 3
B)  Hb 1, Hb 3, Hb 2
C)  Hb 2, Hb 1, Hb 3
D)  Hb 3, Hb 2, Hb 1E) B) and C)
F) A) and D)

Question 18

Which of the following variations between hemoglobins allows for their separation by electrophoresis and chromatography?

Accepted Answer

A)  variations in the amino acid composition of hemoglobins
B)  variations in the heme composition of hemoglobins
C)  variations in the amount of oxygen carried by hemoglobins
D)  variations in the concentration of hemoglobins in the sample under analysisE) A) and C)
F) All of the above

Question 19

In the chromatographic analysis of variant hemoglobins, it is the retention time that determines the _________ and the absorbance that determines the _________.

Accepted Answer

A)  percent concentration, hemoglobin identity
B)  need for further testing, hemoglobin purity
C)  hemoglobin purity, need for further testing
D)  hemoglobin identity, percent concentrationE) A) and B)
F) B) and D) D

Question 20

Perhaps the most significant disadvantage of HPLC analysis of hemoglobins is:

Accepted Answer

A)  the technique is only qualitative and not quantitative
B)  the technique is associated with a high degree of imprecision
C)  the minor differences between the various hemoglobin fractions cause hemoglobins to elute in very narrow, overlapping windows
D)  post-translational modification of hemoglobins produces fractions that often elute with the same retention time as other hemoglobin fractionsE) A) and B)
F) A) and C)

Exam 5: Laboratory Analysis of Hemoglobin Variants

Which of the following is considered the most powerful analytical tool in the laboratory analysis of hemoglobin variants?

Correct Answer
verified
B

Normal hemoglobin fractions seen in HPLC include all but which of the following?

Correct Answer
verified

Hb F may be acetylated in vivo.What is the effect of acetylated Hb F on the measurement of total Hb F (acetylated and non-acetylated) by HPLC?

Correct Answer
verified

Correct Answer
verified

Many HPLC systems utilize "windows" to aid in the interpretation of hemoglobin chromatographic analyses.Which of the following best describes chromatographic windows?

Correct Answer
verified

The Singer 1-minute denaturation test and the Betke 2-minute alkali denaturation test is useful for measuring Hb and is based on this hemoglobin's .

Correct Answer
verified

Hb A2 is often falsely elevated in the presence of __ and falsely reduced in the presence of .

Correct Answer
verified

Hb F is the major hemoglobin fraction present in neonates and is found elevated in various hematologic conditions.Which of the following problems may be encountered in the HPLC analysis of Hb F when it is greatly elevated?

Correct Answer
verified
A

Quantification of Hb A2 following separation by cation-exchange HPLC produced a result of 15% in an Hb AA patient.Which of the following describes a concern the technologist should have regarding this result?

Correct Answer
verified

Correct Answer
verified

Which of the following steps are performed automatically by HPLC systems used in hemoglobin analysis?

Correct Answer
verified

Suppose HPLC results suggest Hb S trait.Why should this be confirmed with the sickle solubility test?

Correct Answer
verified

Your laboratory provides preliminary identification and confirmation of hemoglobin fractions.Suppose your laboratory initially identified a hemoglobin fraction by cation-exchange HPLC.Which of the following techniques should be selected to confirm the presence of the hemoglobin fraction?

Correct Answer
verified

Given that Hb Barts elutes first and Hb C elutes last using cation exchange HPLC, which of the following statements most accurately describes the charge of these hemoglobins under chromatographic conditions?

Correct Answer
verified

Bilirubin is a common interference encountered in the HPLC analysis of hemoglobins, because patients with high levels of bilirubin will show a sharp peak in the same general area as:

Correct Answer
verified

Isoelectric focusing (IEF) may be utilized to investigate unresolved HPLC hemoglobin results.What advantage of this technique makes it useful in this situation?

Correct Answer
verified

Correct Answer
verified

Which of the following variations between hemoglobins allows for their separation by electrophoresis and chromatography?

Correct Answer
verified

In the chromatographic analysis of variant hemoglobins, it is the retention time that determines the _ and the absorbance that determines the _.

Correct Answer
verified
D

Perhaps the most significant disadvantage of HPLC analysis of hemoglobins is:

Correct Answer
verified

Exam 5: Laboratory Analysis of Hemoglobin Variants

Which of the following is considered the most powerful analytical tool in the laboratory analysis of hemoglobin variants?

Correct AnswerverifiedB

Normal hemoglobin fractions seen in HPLC include all but which of the following?

Correct AnswerverifiedShow Answer

Hb F may be acetylated in vivo.What is the effect of acetylated Hb F on the measurement of total Hb F (acetylated and non-acetylated) by HPLC?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Many HPLC systems utilize "windows" to aid in the interpretation of hemoglobin chromatographic analyses.Which of the following best describes chromatographic windows?

Correct AnswerverifiedShow Answer

The Singer 1-minute denaturation test and the Betke 2-minute alkali denaturation test is useful for measuring Hb ________ and is based on this hemoglobin's ________.

Correct AnswerverifiedShow Answer

Hb A2 is often falsely elevated in the presence of __________ and falsely reduced in the presence of ________.

Correct AnswerverifiedShow Answer

Hb F is the major hemoglobin fraction present in neonates and is found elevated in various hematologic conditions.Which of the following problems may be encountered in the HPLC analysis of Hb F when it is greatly elevated?

Correct AnswerverifiedA

Quantification of Hb A2 following separation by cation-exchange HPLC produced a result of 15% in an Hb AA patient.Which of the following describes a concern the technologist should have regarding this result?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following steps are performed automatically by HPLC systems used in hemoglobin analysis?

Correct AnswerverifiedShow Answer

Suppose HPLC results suggest Hb S trait.Why should this be confirmed with the sickle solubility test?

Correct AnswerverifiedShow Answer

Your laboratory provides preliminary identification and confirmation of hemoglobin fractions.Suppose your laboratory initially identified a hemoglobin fraction by cation-exchange HPLC.Which of the following techniques should be selected to confirm the presence of the hemoglobin fraction?

Correct AnswerverifiedShow Answer

Given that Hb Barts elutes first and Hb C elutes last using cation exchange HPLC, which of the following statements most accurately describes the charge of these hemoglobins under chromatographic conditions?

Correct AnswerverifiedShow Answer

Bilirubin is a common interference encountered in the HPLC analysis of hemoglobins, because patients with high levels of bilirubin will show a sharp peak in the same general area as:

Correct AnswerverifiedShow Answer

Isoelectric focusing (IEF) may be utilized to investigate unresolved HPLC hemoglobin results.What advantage of this technique makes it useful in this situation?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following variations between hemoglobins allows for their separation by electrophoresis and chromatography?

Correct AnswerverifiedShow Answer

In the chromatographic analysis of variant hemoglobins, it is the retention time that determines the _________ and the absorbance that determines the _________.

Correct AnswerverifiedD

Perhaps the most significant disadvantage of HPLC analysis of hemoglobins is:

Correct AnswerverifiedShow Answer

Correct Answer
verified
B

Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
verified

The Singer 1-minute denaturation test and the Betke 2-minute alkali denaturation test is useful for measuring Hb and is based on this hemoglobin's .

Correct Answer
verified

Hb A2 is often falsely elevated in the presence of __ and falsely reduced in the presence of .

Correct Answer
verified

Correct Answer
verified
A

Correct Answer
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Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

In the chromatographic analysis of variant hemoglobins, it is the retention time that determines the _ and the absorbance that determines the _.

Correct Answer
verified
D

Correct Answer
verified