Calcium and Magnesium Analysis Quiz Lab

What effect does loss of CO₂ have on ionized calcium samples?

• Lowers pH

• Increases pH

• No effect on pH

• Increases calcium concentration directly

The Orthocresolphthalein Complexone (O-CPC) method for calcium determination produces a color measured at:

• 420 nm

• 480 nm

• 540 nm

• 580 nm

The Arsenazo III dye method has high specificity for calcium at what pH?

• Strongly alkaline pH

• Slightly acidic pH

• Neutral pH

• Strongly acidic pH

Which of the following is the reference method for total calcium determination?

• Arsenazo III dye method

• O-CPC method

• Atomic Absorption Spectrometry (AAS)

• Ion Selective Electrode (ISE)

What effect does leaving the tourniquet on too long have on magnesium results?

• Falsely decreases results

• Falsely increases results

• No effect

• Causes hemolysis only

The most commonly used colorimetric reagent for total magnesium is:

• Arsenazo III

• Orthocresolphthalein complexone

• Calmagite

• Titan yellow

Ionized magnesium measurement using ISE requires correction because:

• ISEs cannot detect Mg²⁺ directly

• ISEs also respond to Ca²⁺ ions

• pH has no effect on readings

• It measures protein-bound magnesium

For urine magnesium analysis, what type of specimen is recommended?

• Random urine sample

• 12-hour urine acidified with HCl

• 24-hour urine acidified with HCl

• First morning urine

Which form of phosphorus is routinely measured in clinical laboratories?

• Organic phosphorus

• Total phosphorus

• Inorganic phosphorus

• Protein-bound phosphorus

The Fiske-Subbarow method for phosphate determination is based on the formation of:

• Ammonium phosphomolybdate complex

• Magnesium-phosphate complex

• Arsenazo III blue complex

• Calcium-phosphate precipitate