chemicalm easurements
analysis
chemical
importantterms
not
usuallyassessed
homogenoussample
itsconstituentpartsvisually indistinguishablefromoneanother
has
eatapwater
samplehas
heterogenous
itsconstituentpartsvisually distinguishable
egsand
is is
analyte thatwhich beingmeasured detected iethe inasampleofmatteraboutwhichchemicalinformationissought
components
cg whenmeasuring the concentration
ofacidafteratitrationtheacidistheanalyte
speciesrefers
tothechemicalofinterest
Interferenceoccurswhen
aspeciesanalyteincreasesdecreasestheresponsebytheanalyticalmethod makingitappearasifthereismorelessofaparticularanalyte
maskingallows aninterferingspeciestobetransformedintoaformthatwillnotbedetectedbytheanalyticalanalysis
Aliquotisaportionwithknownvolumemasstakenfroma largersampleie subsample
,SIunits
time s
length M
mass kg
electricconstant A Ampere
Temperature K
Amiofsubstance mol
luminousintensity od oanoe.la
prefixes
common
onesmustknow
ne ne
red
4000000 tells
blood 100 10 d blood
400000 red cells
ixiooe.pro
1,3010mgon
19 1000,19 100,04
8 101249
,chemical concentrations
saved millipedes
Asolutionisa homogenousmixture
ofsolutes
thesmallestquantity
mikorspeciesalways
how
concentration expresses s olute
m uch is a
containedwithin particular
ofsolution
volume
mm
L caresolution
mm
ite
iiii anion
asa
changes
of
function temperature stays w
c onstant temperature
change
involumeliquidsdependsontemp
molarity molalitywhensolutionconsists ofliquids
loose mono m
I m15,4 1000
100 0mm
mm
p mop
moles n
ideal
gases
Minor
nomotionsroms a pygym
percentc omposition
thepercentageofa component inamixturesolutioncanbeexpressedasa weight wt or volumev01 percent
theunitofmasses volumes doesnotmattersolongastheyarebothofthesameordereggramsonly mionly
we a of
mass solute V01 ofsolute
volume
oftotalsinmixture
mass volumeoftotalsinmixture
acid
109Nitric 1009solution
Kr and 0,825roll 0,825h Kr 1001air
p
PVART
in
L
0033mmol
Carl 0,033279 am
3,3310
100
, molarity molality
men
iii
3iwe 319He1009sin blagme
pay
Osohu.int
If
massme
mgmtroomienaog masssolvent 11909440,39749,79
31111909 440,39
nHa 12,01me
gf
Minqmol aims m1 5
10,1m
partspermillionbillion ppmppb
usedtoexpressconcentrations verydilutesolutions
of
109
ppm of
mass substance 10 ppb massof
substance
massof
s ample massof
s ample
1whendoing calculations with aqueous solutionsthathaveadensity mL
1,009 pom and IPPD
Ma
h ff
30
ppm somgolomon insolution
M and n 0101120
112 10mol
iM
f 4
gym
42.110
1,710am
1h and ppm masssubstanie 10
i m masssample
m
j ppm
morefractions
I ie numberofmolesofa substanceexpressedasafraction ofthetotalnumberofmoles inamixture
v
xi foridealgases Dalton'slawofpartialpressures
, ErrorAnalysis Bstatistics
statisticalt echniques usedtoevaluateerrorsoccurringinanalyticalc hemistry
are
random indeterminateerrors sustematicdeterminateerrors
fromuncontrollableuncontrolledvariablespresentduringmeasurements
arise arise ofanexperiment
fromaflawinequipment design
there
e rrors notbeeliminatedbut
can onlyreducedbyabetter these
errors be
can discovered
and in corrected
priniple
design
experimental
intheywillalwaysbe
present
the individualreadings
on sideotfhemean
tall either thetruevalue ieall
thereplicatemeasurementsdeviatefrom theresultsinaseriesare
toohighortoolow
e ither
is
precision affected randomerrors poor
large precision Accuracy
isaffected
random
errors arerevealedwhenreplicatemeasurementsofa errors
systematic
arerevealedwhentheerrorisreproducibleTheseerrorsmaybe
single are theyaffect
avantity made each decision
if itL
observation
i ndependentist
unpredictably
in
way caitiff ifeng.ptiiige
g whenopeningawindow
change airflow inthelab
affects theair pressurereading
Bias
constant Bias
proportional
Waystodetectsystematic
a
analyze knownsamplecertified material
reference
tocompareresults
measurethesame q u
uantity sing
a m
different ethod
Analyzeablanksampleie analyte nonzero
no results error
standard
reference yieldtrue
m aterials values forthemeasuredavantity
wastocorrect sustomaticerrors
calibrate checkinstruments
Precision reproducibility Accuracy
the
describes obtained
were
internalagreementb etweenresultsthat describeshowclose
a measuredvalueistothetrueacceptedvalue
inthesamewayienowclosethevalvesare to eachother estimated
by comparing
w srm
maybe improved
byrepeatingthemeasurements
Anideal procedureis BOTH precise allurate
limit
bycentral theorem
Gaussian Normal distribution propen
whenanexperimentisrepeatedmanytimesANDtheerrorsarepurelyrandom theresultswilltendtoclustersymmetricallyaboutthemeanvalue
repeating
the moretimes
experiment
theshapeofthe willresemble
measurements
anidealbellshapedcurve GaussianDistribution
shall
setofresults used toestimatethepropertiesofa hypotheticallargeset
sampledataset populationdata set
asmallersetofdatawhichis Alargesetofdatacontainingallpossibledatavalues
apartofa populationdataset
in subset
analysis
chemical
importantterms
not
usuallyassessed
homogenoussample
itsconstituentpartsvisually indistinguishablefromoneanother
has
eatapwater
samplehas
heterogenous
itsconstituentpartsvisually distinguishable
egsand
is is
analyte thatwhich beingmeasured detected iethe inasampleofmatteraboutwhichchemicalinformationissought
components
cg whenmeasuring the concentration
ofacidafteratitrationtheacidistheanalyte
speciesrefers
tothechemicalofinterest
Interferenceoccurswhen
aspeciesanalyteincreasesdecreasestheresponsebytheanalyticalmethod makingitappearasifthereismorelessofaparticularanalyte
maskingallows aninterferingspeciestobetransformedintoaformthatwillnotbedetectedbytheanalyticalanalysis
Aliquotisaportionwithknownvolumemasstakenfroma largersampleie subsample
,SIunits
time s
length M
mass kg
electricconstant A Ampere
Temperature K
Amiofsubstance mol
luminousintensity od oanoe.la
prefixes
common
onesmustknow
ne ne
red
4000000 tells
blood 100 10 d blood
400000 red cells
ixiooe.pro
1,3010mgon
19 1000,19 100,04
8 101249
,chemical concentrations
saved millipedes
Asolutionisa homogenousmixture
ofsolutes
thesmallestquantity
mikorspeciesalways
how
concentration expresses s olute
m uch is a
containedwithin particular
ofsolution
volume
mm
L caresolution
mm
ite
iiii anion
asa
changes
of
function temperature stays w
c onstant temperature
change
involumeliquidsdependsontemp
molarity molalitywhensolutionconsists ofliquids
loose mono m
I m15,4 1000
100 0mm
mm
p mop
moles n
ideal
gases
Minor
nomotionsroms a pygym
percentc omposition
thepercentageofa component inamixturesolutioncanbeexpressedasa weight wt or volumev01 percent
theunitofmasses volumes doesnotmattersolongastheyarebothofthesameordereggramsonly mionly
we a of
mass solute V01 ofsolute
volume
oftotalsinmixture
mass volumeoftotalsinmixture
acid
109Nitric 1009solution
Kr and 0,825roll 0,825h Kr 1001air
p
PVART
in
L
0033mmol
Carl 0,033279 am
3,3310
100
, molarity molality
men
iii
3iwe 319He1009sin blagme
pay
Osohu.int
If
massme
mgmtroomienaog masssolvent 11909440,39749,79
31111909 440,39
nHa 12,01me
gf
Minqmol aims m1 5
10,1m
partspermillionbillion ppmppb
usedtoexpressconcentrations verydilutesolutions
of
109
ppm of
mass substance 10 ppb massof
substance
massof
s ample massof
s ample
1whendoing calculations with aqueous solutionsthathaveadensity mL
1,009 pom and IPPD
Ma
h ff
30
ppm somgolomon insolution
M and n 0101120
112 10mol
iM
f 4
gym
42.110
1,710am
1h and ppm masssubstanie 10
i m masssample
m
j ppm
morefractions
I ie numberofmolesofa substanceexpressedasafraction ofthetotalnumberofmoles inamixture
v
xi foridealgases Dalton'slawofpartialpressures
, ErrorAnalysis Bstatistics
statisticalt echniques usedtoevaluateerrorsoccurringinanalyticalc hemistry
are
random indeterminateerrors sustematicdeterminateerrors
fromuncontrollableuncontrolledvariablespresentduringmeasurements
arise arise ofanexperiment
fromaflawinequipment design
there
e rrors notbeeliminatedbut
can onlyreducedbyabetter these
errors be
can discovered
and in corrected
priniple
design
experimental
intheywillalwaysbe
present
the individualreadings
on sideotfhemean
tall either thetruevalue ieall
thereplicatemeasurementsdeviatefrom theresultsinaseriesare
toohighortoolow
e ither
is
precision affected randomerrors poor
large precision Accuracy
isaffected
random
errors arerevealedwhenreplicatemeasurementsofa errors
systematic
arerevealedwhentheerrorisreproducibleTheseerrorsmaybe
single are theyaffect
avantity made each decision
if itL
observation
i ndependentist
unpredictably
in
way caitiff ifeng.ptiiige
g whenopeningawindow
change airflow inthelab
affects theair pressurereading
Bias
constant Bias
proportional
Waystodetectsystematic
a
analyze knownsamplecertified material
reference
tocompareresults
measurethesame q u
uantity sing
a m
different ethod
Analyzeablanksampleie analyte nonzero
no results error
standard
reference yieldtrue
m aterials values forthemeasuredavantity
wastocorrect sustomaticerrors
calibrate checkinstruments
Precision reproducibility Accuracy
the
describes obtained
were
internalagreementb etweenresultsthat describeshowclose
a measuredvalueistothetrueacceptedvalue
inthesamewayienowclosethevalvesare to eachother estimated
by comparing
w srm
maybe improved
byrepeatingthemeasurements
Anideal procedureis BOTH precise allurate
limit
bycentral theorem
Gaussian Normal distribution propen
whenanexperimentisrepeatedmanytimesANDtheerrorsarepurelyrandom theresultswilltendtoclustersymmetricallyaboutthemeanvalue
repeating
the moretimes
experiment
theshapeofthe willresemble
measurements
anidealbellshapedcurve GaussianDistribution
shall
setofresults used toestimatethepropertiesofa hypotheticallargeset
sampledataset populationdata set
asmallersetofdatawhichis Alargesetofdatacontainingallpossibledatavalues
apartofa populationdataset
in subset
