Chapter 8. Sampling, Standardization, and Calibration

Question 1

uses only a small fraction of the available sample, the
process of sampling is a very important operation.

Answer 1

chemical analysis

Question 2

used to aid in the selection of a representative
sample.

Answer 2

statistical methods

Question 3

are traditionally classified as
gravimetric methods,
volumetric methods, and
instrumental methods.

Answer 3

quantitative methods

Question 4

are those present in the range of 1 to 100% by mass.

Answer 4

major constituents

Question 5

Species present in the range of 0.01 to 1%

Answer 5

minor constituents

Question 6

Those present in amounts between 100 ppm (0.01%) and 1 ppb

Answer 6

trace constituents

Question 7

Components present in amounts lower than 1 ppb

Answer 7

ultratrace constituents

Question 8

A general problem in trace procedures is that the reliability of results usually decreases
dramatically with a decrease in analyte level.

Question 9

The relative standard deviation between laboratories increases as the level of analyte
decreases.

Question 10

If the interferences are caused by extraneous species in the matrix, they are often called

Answer 10

matrix effects

Question 11

Samples are analyzed, but constituents or concentrations are determined.

Question 12

read on sampling uncertainties

Question 13

a miniature replica of the entire mass of material to be
analyzed. It is the collection of individual sampling units. It must be representative of the
whole in composition and in particle-size distribution.

Answer 13

gross sample

Question 14

Well-mixed solutions of liquids and gases require only a very small sample because
they are homogeneous down to the molecular level. Gases can be sampled by several
methods.

Question 15

Samples of metals and alloys are obtained by sawing, milling, or drilling

Question 16

copy formulas in 1/8

Question 17

can lead to higher throughout (more analyses per
unit time), higher reliability, and lower costs than manual sample handling.

Answer 17

automated sample handling

Question 18

These often mimic the operations that would be performed manually.
Some discrete sample processors automate only the measurement step of the
procedure or a few chemical steps and the measurement step.

Answer 18

discrete (batch) methods

Question 19

The sample is inserted into a flowing stream where a number of operations can
be performed prior to transporting it to a flow-through detector.
These methods can perform not only sample processing operations but also the
final measurement step.

Answer 19

continuous flow methods

Question 20

a band-spreading or mixing
phenomenon that results from the
coupling of fluid flow with molecular
diffusion.

Answer 20

dispersion

Question 21

mass transport due to a
concentration gradient.

Answer 21

diffusion

Question 22

determines the relationship between the analytical
response and the analyte concentration, which is usually determined by
the use of chemical standards prepared from purified reagents.

Answer 22

calibration

Question 23

interferences from other constituents in the sample matrix,

Answer 23

concomitants

Question 24

one of the most accurate of all analytical procedures.

Answer 24

titration

Question 25

calibration curve or working curve

Question 26

A series of standard solutions is prepared separately from the sample.

Answer 26

external standard calibration

Question 27

is a rough measure of the
magnitude of a typical deviation from the regression line.

Answer 27

standard deviation about regression

standard error of the estimate

standard error

Question 28

measures the variation in the observed
values of the dependent variable (y values) that are not explained by the presumed linear
relationship between x and y

Answer 28

sum of the squares of the residuals

Question 29

is one in which the variation in the y
values due to the presumed linear relationship is large
compared to that due to error (residuals).

Answer 29

significant regression

Question 30

The F value gives us an indication of the significance of the
regression. When the regression is significant, a large value of
F occurs.

Question 31

gives best estimates of the transformed variables,
but these may not be optimal when transformed back to obtain
estimates of the original parameters.

Answer 31

linear least squares

Question 32

involves adding the interfering species to all the
samples, standards, and blanks so that the interference effect becomes
independent of the original concentration of the interfering species in the
sample.

Answer 32

saturation method

Question 33

is a species, not itself an interfering species, added to
samples, standards, and blanks in sufficient amounts to make the analytical
response independent of the concentration of the interfering species.

Answer 33

matrix modifier

Question 34

is added that reacts selectively with the
interfering species to form a complex that does not interfere.

Answer 34

masking agent

Question 35

can sometimes be used if the interfering species
produces no significant effect below a certain concentration level.

Answer 35

dilution method

Question 36

attempts to duplicate the sample matrix
by adding the major matrix constituents to the standard and blank
solutions.

Answer 36

matrix-matching method

Question 37

Errors in procedures can be minimized by saturating with interfering
species, by adding matrix modifiers or masking agents, by diluting the
sample, or by matching the matrix of the sample.

Question 38

is a reference species, chemically and physically
similar to the analyte, that is added to samples, standards, and blanks.

Answer 38

internal standard

Question 39

The ratio of the response of the analyte to that of the internal standard
is plotted versus the concentration of analyte

Question 40

The response signal is then not the analyte signal itself but the ratio of
the analyte signal to the reference species signal.

Question 41

is used when it is difficult or
impossible to duplicate the sample matrix.

Answer 41

method of standard additions

Question 42

read on chapter 8 in case u missed something

Question 43

the change in
the response signal per unit change in analyte concentration

Answer 43

calibration sensitivity

Question 44

is the ratio of the
calibration curve slope to the standard
deviation of the analytical signal at a given
analyte concentration. The analytical
sensitivity is usually a strong function of
concentration

Answer 44

analytical sensitivity

Question 45

is the smallest
concentration that can be reported with a
certain level of confidence.

Answer 45

detection limit, DL

Question 46

The calibration sensitivity is thus the slope of the calibration curve.

Question 47

most often refers to the
concentration range over which the analyte can be determined using a linear calibration
curve .

Answer 47

linear dynamic range of an analytical method

Question 48

is generally considered to be the detection limit

Answer 48

lower limit

Question 49

is usually taken as the concentration at which the analytical signal or
the slope of the calibration curve deviates by a specified amount

Answer 49

upper end

Question 50

is a sequential plot of some quality characteristic that is important in
quality assurance

Answer 50

control chart

Question 51

determines the suitability of an analysis for providing the sought-for
information and can apply to samples, to methodologies, and to data

is often done by the analyst, but it can also be done by supervisory personnel

Answer 51

validation