Instrumentation

Question 0

Purpose of ion selective electrodes

Answer 0

Generate potential to ion of interest and exclude all others

Question 1

General composition of indicator electrodes

Answer 1

Ion sensitive membrane, electrolyte solution (KCL OR HCL), metal wire (silver chloride), metal element (silver), cable to meter

Question 2

Reference electrode two basic functions

Answer 2

1 provide stable potential

2 complete circuit

Question 3

Components of reference electrode

Answer 3

1 salt bridge-allows ions to enter solution
2 electrolyte solution with HIGH concentration
3 Metal Salt-AgCl wire
4 Metal element-Ag
5 Cable to meter

Question 4

Composition of Saturated Calomel vs Silver/Silver Cloride electrodes

Answer 4

Do not use sat cal bc of mercury and asbestos (carcinogens); Ag/AgCl is used today with increased conc of KCl

Question 5

The measurement of current or amperage created as the voltage applied to an electrochemical cell is changed (ex Oxygen and serum glucose electrodes)

Answer 5

Voltammetry

Question 6

MEASURING AMPHERES. That branch of electrochmistry in which a fixed charge is applied to an electrochemical cell. The charge serves as the generating or excitation signal; the response is the current measured. Molecules are oxidized or reduced at the working electrode, whose potential is controlled relative to a reference electrode.

Answer 6

Amperometry

Question 7

A voltammetric technique in which analysis is based on current/voltage curves produced during electrolysis of a solution. (electrolysis produces chemical changes by passage of an electrical current through an electrolyte)

Answer 7

Polarography

Question 8

What antibiotic is used in potassium ion selective electrodes?

Answer 8

Valinomycin

Question 9

ion selective electrode that measures undiluted sample

Answer 9

direct

Question 10

ion selective electrode that measures pre-diluted sample

Answer 10

indirect

Question 11

How does hyperproteinemia and hyperlipidemia interfere with sodium concentrations on both ion selective electrodes?

Answer 11

Interferes with both, Indirect more affected by both because fat makes it sample a smaller amount

Question 12

How can you correct for lipemia when sodium is affected?

Answer 12

ultracentrifuge

Question 13

What are the essential components of a blood gas analyzer?

Answer 13

3 measuring electrodes (pH, pCO2, pO2), waste pump system, calibration component (2 diff conc of pH, O2, CO2), and humidifying system

Question 14

the number of hydrogen ions needed to raise or lower 1 Liter of whole blood to a pH of 7.40; excess of bicarbonate

Answer 14

Base Excess

Question 15

A whole blood sample is hemolyzed and 4 wavelengths of light pass through the sample

Answer 15

Co-oximeter

Question 16

What is measured with a co-oximeter?

Answer 16

CO Hgb, Oxy Hgb, Met Hgb, Reduced Hgb/total Hgb is calculated

Question 17

properties that depend only on the number of particles in solution, not on the nature of those particles; used in osmolality

Answer 17

colligative properties

Question 18

what are 4 colligative properties?

Answer 18

Freezing point, vapor pressure, boiling point, and osmotic pressure

Question 19

Temperature at which the vapor pressure of the solid and liquid phase are the same

Answer 19

freezing point

Question 20

pressure at which the liquid solvent is in equilibrium with the water vapor

Answer 20

vapor pressure

Question 21

temp at which the vapor pressure of the solvent reaches one atmosphere

Answer 21

boiling point

Question 22

pressure that allows solvent flow between a semi-permeable membrane to establish an equilibrium between compartments of different osmolality

Answer 22

osmotic pressure

Question 23

is freezing point increased or decreased when solute is added to solution?

Answer 23

decreased

Question 24

is vapor pressure increased or decreased when solute is added to solution?

Answer 24

decreased

Question 25

is boiling point increased or decreased when solute is added to solution?

Answer 25

increased

Question 26

is osmotic pressure increased or decreased when solute is added to solution?

Answer 26

increased

Question 27

Units for osmolarity?

Answer 27

mOsm/L of H2O

Question 28

what are the units for osmolality? One we perform in lab

Answer 28

mOsm/Kg of H2O

Question 29

Explain the theory of operation of a freezing point depression osmometer?

Answer 29

The temp of the sample chamber is slightly lowered until below freezing point at which time the stirring rod is activated to promote crystal formation. When temp stablilizes it is read as the freezing point depression.

Question 30

Essential components of a freezing point depression osmometer

Answer 30

1 electrode in bath of ethylene glycol (antifreeze)
2 stir wire causes immediate freezing with vibration
3 thermistor probe measures heat of fusion release by formation of crystals
4 sample cup

Question 31

The coulometric titrator consists of the ______ electrode and ________ electrode pair

Answer 31

indicator; generator

Question 32

this electrode is made of Ag and is the coulometric part of the titrator

Answer 32

generator electrode

Question 33

this electrode is the amperometric part of the titrator, it senses end of the reaction of free Ag ions

Answer 33

indicator electrode

Question 34

the _____ electrode senses the current and shuts down the titration when the end point is reached

Answer 34

indicator electrode

Question 35

this electrode is immersed in a soln containing dissolved CO2 gas; the silicone rubber membrane allows the gas to pass into an internal sodium bicarbonate buffer soln. A pH indicator and reference electrode are immersed in the buffer soln. CO2 reacts with the buffer and the pH change is sensed to measure the CO2.

Answer 35

Stow and Severinghaus (pCO2 electrode)

Question 36

This electrode is immersed in a solution containing dissolved O2 gas, polypropylene membrane allows O2 to apss into the internal phosphate buffer soln; O2 then reacts with polarized platinum cathode (high sensitivity and fast response); silver anode provides the oxidizing electrode to complete the circuit.

Answer 36

Clark (pO2 electrode)

Question 37

As O2 is consumed we get a negative charge which is proportional to pCO2 in blood gas; polarographic electrode with oxidation/reduction reactions

Answer 37

Clark (pO2) electrode…shorter description

Question 38

O2+2H2O+4e—>4OH

Answer 38

oxidation reduction reaction in Clark

Question 39

CO2+H2OHCO3+H3O

Answer 39

changes pH in Stow and Severinghaus electrode

Question 40

more CO2= ______ in pH and ______ H ions in pCO2 electrode (S&S)

Answer 40

decreased pH and increased H ions

Question 41

Chemical reactions occuring because of the flow or presence of electrons. It is thus governed by the actual transfer of energy from electrons to chemicals, or the potential for such transfer. The chemicals are in contact with the electrons at surfaces or interfaces.

Answer 41

Electrochemistry

Question 42

Describes the flow of electrons through a substance, such as a solution or a wire, and is measured in amperes, or coulombs of change per second.

Answer 42

current

Question 43

the opposition of a substance to current flow, measured in ohms

Answer 43

resistance

Question 44

the ability to do work, the degree of electrification as compared to some standard. for current to flow, the potential applied to the system must be greater than the resistanace exhibited by that system.

Answer 44

potential

Question 45

the measurement of the potential difference between two electrodes measured at equilibrium and with no current. the potential generated is proportional to the activity (conc) of the ion being measured.

Answer 45

potentiometry

Question 46

a bridge of a salt soln, usually KCl, placed between the two half-cells of a galvanic cell, either to reduce the potential of the liquid junction between the solns of the two half cells to a minimum or to isolate a soln under study from a reference half-cell and prevent chemical precipitations.

Answer 46

salt bridge