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ANALYTICAL CHEMISTRY C3 > Chapter 6: Sampling, Standardization, and Calibration > Flashcards

Chapter 6: Sampling, Standardization, and Calibration Flashcards

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1
Q

are traditionally classified as gravimetric methods, volumetric methods, or instrumental methods

A

quantitative methods

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2
Q

an analysis used for samples whose masses are greater than 0.1 g

A

macro analysis

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3
Q

is performed on samples in the range of
0.01 to 0.1 g

A

semi-micro analysis

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4
Q

is performed on samples in the range of
10^-4 to 10^-2 g

A

micro analysis

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5
Q

is performed on samples in less than 10^-4 g

A

ultramicro analysis

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6
Q

TRUE or FALSE
Techniques for handling very small samples are quite different from those for treating macro samples.

A

TRUE

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7
Q

species present in the range of 0.01 to 1% are usually termed

A

minor constituents

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8
Q

species present in the
range of 100 ppm (0.01%) and 1 ppb are called

A

trace constituents

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9
Q

Components present in amounts lower than 1 ppb are usually considered to be

A

ultratrace constituents

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10
Q

The analysis of real samples is complicated by the presence of the

A

sample matrix

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11
Q

can contain species with chemical properties similar to the analyte. can react with the same reagents as the analyte, or they can cause an instrument response that is not easily distinguished from the analyte.

A

Matrix

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12
Q

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

A

matrix effects

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13
Q

The process of acquiring a
representative fraction is termed

A

sampling

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14
Q

is often the most difficult
aspect of an analysis.

A

sampling

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15
Q

TRUE or FALSE
The composition of the gross
sample and the laboratory
sample must closely resemble
the average composition of
the total mass of material to be
analyzed

A

TRUE

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16
Q

Steps in obtaining a lab sample

A

identify the population
collect a gross sample
reduce the gross sample to a laboratory sample

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17
Q

representative portion of a whole analytical sample, which with further treatment, becomes the laboratory sample

A

gross sample

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18
Q

The items chosen for analysis are often called

A

sampling units or sampling increments

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19
Q

chemists usually call
the collection of sampling units or increments the

A

gross sample

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20
Q

gross sample is usually reduced in size and
homogenized to create the

A

laboratory sample

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21
Q

Statistically, the goals of sampling process are

A

obtain a mean analyte concentration for an unbiased estimate of population mean
obtain a variance in the measured analyte concentration for an unbiased estimate of the population variance

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22
Q

can reveal whether the between
samples variation (sampling variance plus measurement variance) is significantly
greater than the within samples variation (measurement variance).

A

analysis of variance

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23
Q

TRUE or FALSE
Errors due to invalid sampling
are unique in the sense that they are not controllable by the use of blanks and
standards or by closer control of experimental variables. For this reason, sampling errors are usually treated separately from the other uncertainties associated with an analysis

A

TRUE

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24
Q

is a miniature replica of the entire mass of material to be analyzed. It should correspond to the bulk material in chemical composition and in particle-size distribution if the sample is composed of particles.

A

gross sample

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25
Q

gross sample is acquired by

A
  1. uncertainty that can be tolerated
  2. degree of heterogeneity of the whole
  3. level of particle size, which heterogeneity begins
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26
Q

is a state intermediate between a suspension and a solution.

A

colloid

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27
Q

intermediate between heterogeneity that develops in particles that may have dimensions on the order of a centimeter or more and maybe several in grams are called

A

colloidal materials and solidified metals

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28
Q

the constant Ks is called the

A

Ingamells sampling constant

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29
Q

is a container that can be opened
and filled at any desired location in the solution.

A

sample thief

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30
Q

TRUE or FALSE
With large volumes of solutions, mixing may be impossible. It is then best to sample several portions of the container with a “sample thief,”

A

TRUE

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31
Q

What is used to collect vapor samples

A

gas-tight syringe or stainless steel canister

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32
Q

TRUE or FALSE
The laboratory sample should
have the same number of
particles as the gross sample.

A

TRUE

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33
Q

samples of metals are obtianed by

A

sawing
milling
drilling

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34
Q

TRUE or FALSE
With some materials, a representative sample can be obtained by sawing across the piece at
random intervals and collecting the “sawdust” as the sample.

A

TRUE

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35
Q

the steps in sampling a particulate solid includes

A

crushing
grinding
seiving
mixing
dividing the sample to reduce its mass

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36
Q

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

A

automated sample handling

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37
Q

two different methods for automated sample handling

A

batch or discrete approach
continuous flow approach

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38
Q

A method where Automated instruments that process samples in a discrete manner often mimic the operations that would be performed manually.

A

Discrete methods

39
Q

In continuous flow methods, 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. Hence, these systems behave as automated analyzers in that they can
perform not only sample-processing operations but also the final measurement step.

A

continuous flow methods

40
Q

discrete methods do

A

dilute
filter
partition
grind
centrifuge
homogenize
extract
treat samples with reagent

41
Q

continuous flow method do

A

reagent addition
dilution
incubation
mixing
dialysis
extraction

42
Q

2 different types of continuous flow systems

A

segmented-flow analyzers
flow injection analyzers

43
Q

divides the sample into discrete segments separated by gas bubbles

A

segmented-flow analyzer

44
Q

is a more recent development, samples are
injected from a sample loop into a flowing stream containing one or more reagents

A

flow injection analysis

45
Q

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

A

dispersion

46
Q

is mass transport due to a
concentration gradient.

A

diffusion

47
Q

the sample and reagent are both injected into carrier streams and merged
at a tee mixer.

A

merging zones flow injection analysis

48
Q

sample dispersion is controlled
by the sample size, the flow rate, and the length and diameter of the tubing. It is also
possible to stop the flow when the sample reaches the detector to allow concentrationtime profiles to be measured for kinetic methods

A

flow injection analysis/ merging zone FIA

49
Q

determines the relationship between the analytical response and the analyte concentration

A

calibration

50
Q

the relationship of analytical response and the analyte concentration (calibration) is determined by

A

chemical standards

51
Q

Constituents of a sample other than
the analyte are called

A

concomitants

52
Q

Concomitants that interfere
with the determination of an
analyte may be referred to as

A

interferences or interferents

53
Q

needs to indicate whether the threshold has been exceeded

A

comparator

54
Q

Some analytical procedures involve comparing a property of the analyte (or the product of a reaction with the analyte) with standards such that the property being tested matches or nearly matches that of the standard are called as

A

null comparison or isomation methods

55
Q

are among the most accurate of all analytical procedures, the analyte reacts with a standardized reagent (the titrant) in a known stoichiometric manner.

A

titration

56
Q

a type of calibration process in which a series of standard solutions is prepared separately from the sample, The standards are used to establish the instrument calibration function, which is obtained from analysis of the instrumatrment response as a function of the known analyte concentration.

A

external standard calibration

57
Q

A plot of instrument response versus
known analyte concentrations is used
to produce a

A

calibration curve or working curve

58
Q

provides the means for objectively determining such a line and also for specifying the uncertainties associated with its subsequent use

A

regression analysis

59
Q

Least squares method two assumptions

A

linear relationship between the measured response y (absorbance in Figure 6-10) and the
standard analyte concentration x

any deviation of the individual points from the straight line results from error in the individual measurements

60
Q

The vertical deviation of each point from
the straight line is called a

A

residual

61
Q

simple least-squares analysis may
not be appropriate when the uncertainties in the y values vary significantly with x. In
that instance, it may be necessary to apply different weighting factors to the points
and perform a

A

weighted least square analysis

62
Q

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

A

SD abour regression/ standard error of the estimate/ standard error

63
Q

measures the fraction of the observed variation in y that is explained by the linear relationship and

A

coefficient of determination R^2

64
Q

The process of relating multiple
instrument responses to an analyte or a mixture of analytes is known as

A

multivariate calibration

65
Q

The least-squares procedure just described is an example of a

A

univariate calibration

66
Q

The use of multivariate statistical methods for
quantitative analysis is part of the subdiscipline of chemistry called

A

chemometrics

67
Q

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

A

saturation method

68
Q

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

A

matrix modifier

69
Q

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

A

masking agent

70
Q

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

A

dilution method

71
Q

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

A

matrix-matching method

72
Q

a type of calibration method in which a known amount of a reference species is added
to all the samples, standards, and blanks

A

internal standard method

73
Q

We use the _______________ when it is difficult or impossible to duplicate the sample matrix. a known amount of a standard solution of analyte is
added to one portion of the sample

A

method of standard additions

74
Q

additions of known amounts of
standard analyte solution are made to several portions of the sample, and a multiple additions calibration curve is obtained.

A

multiple additions method

75
Q

is a general term that applies to many fields including analytical
chemistry. It is a numerical expression representing the
performance or efficiency of a given device, material, method,
or procedure.

A

figures of merit

76
Q

Analytical procedures are characterized by a number of figures of merit

A

accuracy
precision
sensitivity
detection limit
dynamic range

77
Q

the change in the measured quantity per unit change in analyte concentration. slope of the calibration curve

A

calibration sensitivity

78
Q

Scatter in the response is also called as

A

noise

79
Q

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

A

detection limit

80
Q

TRUE or FALSE
A k value of 2 corresponds to a confidence level of 92.1%, while a k value of 3 corresponds to a 98.3% confidence level

A

TRUE

81
Q

of an analytical method most often refers to the concentration range over which the analyte can be determined using a linear calibration
curve

A

linear dynamic range

82
Q

is a sequentialplot of some characteristic that is a
criterion of quality.

A

control chart

83
Q

if the value is within the upper control limit and lower control limit, the balance is said to be in

A

statistical control

84
Q

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

A

validation

85
Q

is the final step before release of the results

A

data validation

86
Q

a known amount of
a standard solution of analyte is
added to one portion of the sample

A

method of standard additions/ standard addition method

87
Q

This standard
additions method assumes a linear
response

A

multiple additions method

88
Q

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

A

standard deviation about
regression, also called the standard
error of the estimate or just the
standard error

89
Q

is identical to the sample but without the analyte.

A

ideal blank

90
Q

Most often a real blank is either a ___________, containing the same solvent in which the sample is dissolved

A

solvent blank

91
Q

containing the solvent plus all the reagents used in sample preparation.

A

reagent blank

92
Q

contains the solvent or the solvent plus all the reagents used to prepare the samples.

A

blank

93
Q

is the ratio of the calibration curve slope to the standard deviation of the analytical signal at a given analyte concentration.

A

analytical sensitivity

94
Q
A

ANALYTICAL CHEMISTRY C3 (21 decks)

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