lab math lect.pptx

8/10/2019 lab math lect.pptx

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Lab. Mathematics


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Henderson hasselblach equation Timed urine (24 hr urine calculation) Creatinine clearance Enzymes units & calculation Spectrophomtometric osmolality Units conversion Statistical quality control


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Henderson-Hasselbalch equation

PH = pk + log [Base] [acid]

PH = 6.1 + log [HCO 3- ]

[H2CO3]

PH = 6.1 + log [HCO 3- ]

[0.03 P CO2]


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Calculate the pH of a buffer solution madefrom 0.20 M HC 2H3O2 and 0.50 M C 2H3O2-

that has an acid dissociation constant forHC2H3O2 of 1.8 x 10 -5


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pH = pKa + log ([A-]/[HA]) pH = pKa + log ([C2H3O2-] / [HC2H3O2])

pH = -log (1.8 x 10-5

) + log (0.50 M / 0.20 M) pH = -log (1.8 x 10 -5) + log (2.5) pH = 4.7 + 0.40 pH = 5.1


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Creatinine clearance

The calculated creatinine clearance is corrected to bodysurface area of 1.73m2 which is standard BSA for adults.

Corrected CrCr (m/min) = CrCr X A/1.73(A = Body surface area ) = W0.425 X H0.725 X 0.007184


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Timed urine values 24 hr urine for

protein Calcium Na CreatinineReported as1. Value taken directly from instrument (mg/dl , g/l ,

mol/L)1. Example Na = 160 mmol/l (total volume =2400 , time 24

hr)2. Quantity per total volume

1. Na = 160 mmol/l = (160/1000)*2400 = 340mmol/2400ml3. Quantity per unit of time of collection

1. Na =160mmol/l = (160/1000)*2400 = 340mmol/24hr


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To report as quantity /time of collection : just change the description of the total volumeTo the period of time collection

Timed urine values


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Timed urine values

Calculate the amount of protein in 1800 ml for aurine having 40mg/dl(720mg/1800ml). A 24-hr urine measuring 1800ml has protein conc.

Of 40 mg. find the amount of protein per day.

If 3.4g% of albumin was found in a 24-hr urinesample with volume of 1500 ml , how manyg/24hr did the patient excrete?(51g/d).

A 2 hr urine amylase was to be 105 unit/dl. The

total volume is 255ml. Report as: Unit /2hr(267.8). Units/ml(1.05units/ml). Units/255ml(267.8units/225ml).


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Enzyme calculations

Kinetic methods The reaction rate is proportional to time and

enzyme concentration End points


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1/ Fixed time or End pointAll reactant are combined and reaction

proceed to designated time and then reactionis stopped

2/ Kinetic AssayMultiple measurements are made during thereaction at the specific time interval ( every 30sec or 60 sec.)

Measurement of enzyme activity


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In Kinetic assay , the NADH is a co-enzymefrequently measured.

NADH absorb light at 340nm, whereas NAD dosenot, therefore change in absorbance at 340nm iseasily measured.



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I.U : the amount of enzyme that catalyze theconversion of 1mole of substrate per minute

under defined conditions of TP, pH, substrate Katal: The amount of enzyme that catalyze the

conversion of 1 mole of substrate per secondunder define condition of TP, PH and substrate.


Calculating enzymes activity (Enzyme activity units)


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Spectrophotometry

A spectrophotometer is an instrument thatmeasures the transmitted light of a solution

and allows the operator to read theabsorbance of the solution on a meter.


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Spectrophotometry

Relationship between transmittance &absorbance Transmittance (T) = proportion of incident light

that is transmitted and expressed as percent

T = Is/I o (1s = transmitted light , Io is incident light T% = (Is/I o )* 100 By definition , Absorbance (A) = -log T T% = (T)*100

T = T%/100 A = -log(T%/100) A= log(100/T%) A= log100- logT%) A= 2-logT%


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Bears law: State that the concentration of substance is directly

proportional to the amount of light absorbed or inverselyproportional to the logarithm of transmitted light.Mathematically is expressed as

A= abc

A= absorbancea = absorptivity (e , molar absorptivity)b = light path in cmc = concentration


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Calculation of plasma Osmolality

mOs/kg = = 1.86 (Na[mmol/l])+ glucose[mmol/l]+ urea[mmol/l)+ 9

Or mOs/kg = = 1.86 (Na[mmol/l])

+ glucose[mg/dl]/18

+ BUN [mg/dl)/2.8+ 9

Reference Range: 275 to 300 mSm/kg


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System of measure & SI units


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Concentration

. A percent solution can be described as: (1) w/w, which is expressed as weight (mass) per 100

units of weight (g/g). (2) w/v, which is expressed as weight (mass) per 100

units of volume (g/dL). (3) v/v, which is expressed as volume (mL) per unit of

volume (mL).

% X Total (V or W) = amount from conc , complete it to total


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Concentration b. Molarity (M) is expressed as moles per liter (mol/L) or

millimoles per milliliter (mmol/mL).

W =M X MW X V

10001. How many grams are needed to make 1 L of a 2 M solution of HCl?

2. A solution of NaOH is contained within a Class A 1 volumetric flask filled to

the calibration mark. The content label reads 24 g of NaOH. Determine themolarity.


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Normality (N) is expressed as equivalentweight (Eq wt) per liter of volume (Eq/L ormEq/mL).

1. NaCl (gmw 58 g, valence 1)

A. What is the normality of a 500-mL solution that contains7 g of H2SO4?

N = M X V


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Factors and dilutions

Factor : number used to produce results insingle calculation that otherwise needs severalsteps fro calculation

Factor to express quantity one substanceequivalent to another substance (ratio orproportion)

urea : MW 60 , contain 2N = 28 Factor to convert BUN to urea = 60/28 = 2.14


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Factor : number used to produce results insingle calculation that otherwise needs severalsteps fro calculation

By known relationship Find amount of NaCl that equivalent to 100mg of

Na Factor = MW of desired material /MW of existing

material 58.5/23 = 2.56 This factor convert Na into NaCl How many NaCl is needed to prepare Na standard

140mmol/l ??


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Dilutions : addition of one substance toanother substance to reduce concentration ofone substance (number of part of materialbeing diluted in the total numbers of parts of

the final product) Ratio Vs dilution

Serum to saline ratio 1:9 Saline to serum is 9:1 Serum to total volume ration 1:10

Dilution refer to one thing : number of parts(substance diluted) in total number of all parts)

Symbols : / , In or ration to total volume


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Examples If 8 ml of saline is added to 2ml serum

Saline to serum ration Saline to total volume ratio Serum to saline ratio

Dilution of serum A total of 400ml of dilution is to be prepared . How much 1/10 solution to made from 5 ml of

concentrated solution How to get 5 ml urine diluted 1/50 How would you make 300 ml alcohol of 2/5

dilution of alcohol


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Convertion of units

Conversion Convert 8.2 mg/dL calcium to millimoles per liter

(mmol/L) , mEq/l Percent to SI unit Enzymes (IU to Katal or


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Statistical quality control

Distribution & central tendency Normal Distribution Mean , median , SD , CV precision , accuracy Quality control charts

Levey & Jennings chart Other charts


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Statistical quality control

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lab math lect.pptx