crystallize r

8/13/2019 Crystallize r

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CHEE 450: Insulin Design Project

CRYSTALLIZATION

UNIT

Rachel Adams

Jana DenglerMegan MacLeod

Kyla Sask


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CRYSTALLIZATION UNIT

Outline

Purpose of Crystallizer

Methods of Crystallization

Design Specifications

Engineering Drawing

Alternative Cost and Suppliers

Alternative Processes

Questions


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Purpose of Crystallizer

Used to recover pure solids from solution

Highly desirable end product because of:

Exceptional purity Ease of handling

Long shelf life

One of the final treatment steps in thepurification and concentration of insulin

98% of the insulin must be crystallized


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Mechanism of Crystallization

Crystal nucleation and amorphous precipitatesare in competition during supersaturationconditions

Nucleation favored by slowly exceeding theequilibrium point of saturation

permits time for the protein structure

to orient in a crystalline lattice


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Continuous or Batch Design

Benefits of Continuous

Can maintain solution in supersaturated state

Large fluidized bed for crystallization

Minimizes operation costs Minimize down time (startup and shutdown)

Benefits of Batch

Good when have low concentration of product, highviscosity or many impurities

Can produce high quality crystal


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Methods of Crystallization

Supersaturation: liquid (solvent) contains moredissolved solids (solute) than can ordinarily beaccommodated at that temperature

Can be achieved by several methods:

Cooling

Evaporation Solvent addition

Precipitant Addition


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Cooling Method

Concentrated solutiongradually cooled belowsaturation temperature(50-60C) to generate asupersaturated state

Yields well definedmicron-sized crystals

Shell and tube heatexchanger is used tocool solution


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Cooling Method

Advantages: High purity downstream

Disadvantages:

Temperature change does not always have a positiveeffect on supersaturation in proteins

Protein stability may be at risk

Solubility can be relatively insensitive to temperatureat high salt concentrations

Cooling will only help reach supersaturation insystems where solubility and temperature are directlyrelated


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Evaporation Method

Solute dissolves in solution when heated to acertain temperature (75C)

Slowly cooled until crystals precipitate

Shell and tube heat exchanger is used to heatand cool solution


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Evaporation Method

Advantages:

high purity levels downstream

Disadvantages:

Vaporization chamber requires high pressures

Protein viability very sensitive to hightemperatures


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Solvent Method

Solvents are generally good proteinprecipitants

Their low dielectric constants lower the

solvating power of their aqueous solutions Requires acidic solvent

For crystallization, an insulin protein fallsout of solution at isoelectric point

pH 5.4-5.7


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Solvent Method

Advantages:

Proteins viability not at risk due totemperature change

Disadvantages:

Possible protein contamination due toinsufficient downstream solvent recovery


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Addition of Zinc Ions

In the presence of zinc ions, insulin proteinsorient to form hexamer structures

Zinc ions render insulin insoluble which resultsin micro-crystallization and precipitation

Human Insulin Hexamer with Zinc ion


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Seeding Techniques

Primary nucleation is the first step incrystallization - growth of a new crystal Can bypass primary nucleation (creation of

new crystals) by "seeding" the solution

Secondary nucleation is crystal growth

initiated by contactAccelerated by "seeding" adding existinginsulin crystals to perpetuate crystal growth


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Crystal Size and Growth Rate

Assumptions: Continuous Constant-volume Isothermal Well-mixed

Relates population densityand crystal size

GL

Lk

Lk

v

a

/expnn

M:MassCrystal

A:AreaCrystal

o

3

c

2

c

Mechanism of crystal growthto determine crystal growth s

v

as cc3dt

dL

k

kk


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Crystallizer Design

Addition of acidic solvent to decrease pH toachieve supersaturation

Addition of Zinc ions to initiate Insulin

precipitation Implementing of seeding technique

Minimize heat variation to maintain protein

stability Washing and extensive solvent recovery

downstream


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Design Equations

2.5DH

H4DV

slurryofgravityspecific24.6

slurryofqualityVolume

crystalsofsg75.0solutioofsg25.0

crystalsofsgsolutionofsgslurryofgravitySpecific

.25quantity/0crystalqualitySlurry

flowratetimeretentionquantityCrystal

2


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Proposed Design

Temperature 25 C

Pressure 1.013 bar

Flowrate 111.842 kg/batch

Volume 0.29 m3

Diameter 0.529 m

Height 1.325 m

Residence Time 23.98 h


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Engineering Drawing

http://sundoc.bibliothek.uni-halle.de/diss-online/04/04H181/prom.pdf


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Costing Estimates

Three costs involved:

Crystallizer unit

Zinc Chloride Solution and Water

Power Requirements


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Costing Estimates

Crystallizer Unit www.matche.com
http://www.matche.com/http://www.matche.com/


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Costing Estimates

Crystallizer Unit

Batch, Atmospheric Crystallizer

0

10000

20000

30000

40000

50000

60000

70000

80000

0.00

0.15

0.30

0.45

0.61

0.76

0.91

1.06

1.21

1.36

1.52

1.67

1.82

1.97

Size (m3)

Cost(US$

)

Carbon Steel Stainless Steel


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Costing Estimates

Zinc Chloride Solution

Many suppliers

$15.00 - $27.00 for 500g

Power Requirements

Canadian Hydro: 8.99 cents/kWh (April, 2006)


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Crystallizer Suppliers

GEA Niro Inc. Companies in over 50 countries

Copenhagen, Columbia, Germany, USA

GEA Kestn er Evapo rator/Crystal l izer

Swenson Technology Inc. Illinois, USA

HPD Inc. Illinois, USA


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Alternative Processes

For special drug purposes and when azinc-free product is needed

Alternative processes that can be usedinclude:

Isoelectric Precipitation

Gel Chromatography

Ultrafiltration


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Isoelectric Precipitation

Protein purificationprocedure that can beused with crystallizationor on its own

The pH of a mixture is adjusted to the pI of theprotein to be isolated to selectively minimize itssolubility


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Gel Filtration Chromatography

Molecules are separatedaccording to their size andshape

Filtration column is filled withporous beads

Solution passes throughcolumn

Elution through the gel occursin order of decreasingmolecular masses


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Ultrafiltration

Ultrafiltration used to concentratemacromolecular solutions

Forced under pressure or by centrifugation

through a semipermeable membranous disk Solvent and small solutes pass

through the membrane, leaving

behind a more concentratedmacromolecular solution


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crystallize r

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