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Calibration and use of Balances in a Quality System

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Title: Calibration and use of Balances in a Quality System


1
Calibration and use of Balances in a Quality
System
2
Calibration and Daily use of Balances
  • Tony Kowalski
  • Sartorius Lab Weighing
  • Tel. 01372 737102

3
Calibration and Daily use of Balances
  • Balances and Scales in Quality Systems
  • Equipment Qualification
  • Terminology
  • Good weighing Practice
  • Calibration
  • Calibration Weights

4
Calibration and Daily use of Balances
  • Balances under 90/384/EEC
  • Choosing the right balance acc. to USP
  • Uncertainty of measurement
  • Setting appropriate pass fail criteria
  • Summary and Open Question Session

5
Why do we need a quality System like GLP
  • To avoid Litigation Claims
  • To build purchaser-supplier confidence
  • To maintain marketability
  • To optimise costs/profitability

6
Good Laboratory Practice (GLP) Requires
  • Qualified and competent personnel
  • Defined appropriate equipment and conditions
  • Testing facility designed to minimise problems
  • Record management/Archive

7
Good Laboratory Practice (GLP) Requires
  • Suitable Test and Reference Standards and
    Internal Audit System
  • Documented SOPs
  • Regular Calibration of Measuring Equipment
    According to Accepted Methods

8
For GLP Balances have printouts to identify
  • Model Manufacturer
  • Serial number
  • Software version number
  • All adjustment routines

9
For GLP Premium Balances have these features
  • Internal Adjustment Weights
  • Real Time Clock
  • Alpha Numeric Data Input
  • Bar Code Scanner Connectivity for sample IDs

10
Typical GLP/GMP Compliant Printout
  • 13.11.1998 11.45.23
  • Sartorius AG
  • Model LP6200S
  • Ser. no. 60419914
  • Ver. no. 01-30-01
  • ID QCLab 22
  • -----------------------------------------------
  • Internal Calibration
  • Start isoCAL/temp
  • Diff. 0.07g
  • Internal adjustment completed
  • Diff. 0.00g
  • -----------------------------------------------
  • 13.11.1998 11.46.23
  • Name Joe Bloggs

11
Typical GLP/GMP Compliant Printout
  • 13.11.1998 11.45.23
  • Sartorius AG
  • Model LP6200S
  • Ser. no. 60419914
  • Ver. no. 01-30-01
  • ID QCLab 22
  • -----------------------------------------------
  • Internal Calibration
  • Start isoCAL/temp
  • Diff. 0.07g
  • Internal adjustment completed
  • Diff. 0.00g
  • -----------------------------------------------
  • 13.11.1998 11.46.23
  • Name Joe Bloggs

12
Typical GLP/GMP Compliant Printout
  • 13.11.1998 11.45.23
  • Sartorius AG
  • Model LP6200S
  • Ser. no. 60419914
  • Ver. no. 01-30-01
  • ID QCLab 22
  • -----------------------------------------------
  • Internal Calibration
  • Start isoCAL/temp
  • Diff. 0.07g
  • Internal adjustment completed
  • Diff. 0.00g
  • -----------------------------------------------
  • 13.11.1998 11.46.23
  • Name Joe Bloggs

13
Typical GLP/GMP Compliant Printout
  • 13.11.1998 11.45.23
  • Sartorius AG
  • Model LP6200S
  • Ser. no. 60419914
  • Ver. no. 01-30-01
  • ID QCLab 22
  • -----------------------------------------------
  • Internal Calibration
  • Start isoCAL/temp
  • Diff. 0.07g
  • Internal adjustment completed
  • Diff. 0.00g
  • -----------------------------------------------
  • 13.11.1998 11.46.23
  • Name Joe Bloggs

14
Hardware Validation or IQ/OQ
  • Equipment Qualification EQ
  • What is it?
  • Why?
  • Description!!

15
Installation Qualification or IQ
  • Completeness Check
  • Record Serial
  • Software Version
  • Location
  • Accessories
  • Appropriate Safety Standards

16
Operational Qualification or IQ
  • Testing against Specification
  • Subject to Environmental conditions
  • Testing Functionality of Balance
  • Essentially a Full Calibration

17
Performance Qualification PQ
  • Performed by the Operator
  • Daily or Weekly
  • User Defined
  • One or Two Calibration Weights
  • Outlined in the SOP

18
Design Qualification DQ
Design Qualification DQ
  • Confirmation that the Equipment is Suitable for
    the Application
  • Can include Copies of Quality/Safety Certificates

19
Finally The Maintenance Log
1 Tonne
  • Record of Service Visits
  • Calibration Results
  • Any Repairs Done
  • Modifications
  • Date of Next Visit

20
Calibration and Daily use of Balances
  • Terminology
  • Weight Units
  • Basic Principle of an Electronic Balance
  • Care in the use of balances
  • Hazards to avoid

21
Terminology
Is this you?
  • Accuracy
  • Readability
  • Sensitivity
  • linearity Error
  • Repeatability
  • Uncertainty

Then order your copy of The Fundamentals of
weighing - Now!
22
Accuracy
  • Is the extent to which the readout approaches the
    true value of the object.

23
Readability
  • The smallest difference that can be measured.
  • Resolution or Discrimination

24
Reproducibility of a Balance
0.01g
25
Reproducibility of a Balance
0.03g
26
Linearity - Deviation from Theoretical Strait Line
27
Linearity - Deviation from Theoretical Strait Line
28
Linearity - Deviation from Theoretical Strait Line
0.01g
29
Sensitivity Drift
  • Quantitative measure of drift per degree Celsius.
  • (2x10-6) x (5C) x 10g 0.1mg
  • 1 Error!
  • Defined Temperature Range between 10-30C
  • isoCal

30
Errors - out of level weighing
  • Balance table 1m x 1m
  • Raise one side 5mm
  • Before 200.00000g
  • After 199.99850g
  • Difference 0.00150g

31
Errors - changes in regional gravity
  • Ground Floor 200.00000g
  • First Floor 199.99974g
  • Difference 0.00026g

32
Weight Units
33
(No Transcript)
34
Good Weighing Practice
  • Keep Balance Clean
  • Site Balance on Firm Surface
  • Level the balance
  • Free from Drafts
  • Not in Direct Sunlight
  • Not near a Radiator

35
Good Weighing PracticeHazards to Accuracy
  • Electro Static Influences from
  • Plastic Containers
  • Oven Dried Glassware
  • Some Samples
  • Magnetic/ Electromagnetic Effects
  • Stirring Bar!
  • Steel Containers

36
Calibration and Daily use of Balances
  • Calibration weights
  • Design
  • Class of weights
  • How to Adjust a Balance
  • Internal v External Weights
  • Daily Calibration Checks

37
Metrology and Standards(which is the odd one
out?)
  • m Meter
  • s Second
  • A Ampere
  • K Kelvin
  • cd Candela
  • kg Kilogram
  • Length
  • Time
  • Electric Current
  • Temperature
  • Luminous Intensity
  • Mass

38
Metrology and Standards(which is the odd one
out?)
  • m Meter
  • s Second
  • A Ampere
  • K Kelvin
  • cd Candela
  • kg Kilogram
  • Length
  • Time
  • Electric Current
  • Temperature
  • Luminous Intensity
  • Mass

39
The International Prototype kilogram
Definition
  • The International prototype kilogram is-
    The mass of the international prototype which is
    held at the BIPM in Paris
  • Cylinder of Platinum - iridium (90Pt, 10Ir)
    39mm diameter, density 21.5gcm-3

40
The National Measurement System
41
The National Measurement System
42
The National Measurement System
43
The National Measurement System
44
The National Measurement System
45
Calibration Weights and OIML
  • Organisation International de Metrology Legale
  • Specifies Design, Material,
    Surface Quality, Tolerances, Markings,
    Manufacture
  • RI 111

46
Classes of Calibration Weights
  • E1 Solid Stainless Steel
    No markings. 1kg /- 0.5mg
  • E2 Solid stainless Steel
    No markings 1kg /- 1.5mg
  • F1 Stainless Steel with
    adjustment cavity 1kg /- 5.0mg

47
Conventional mass
  • The certified mass of a weight is not its true
    mass
  • but is
  • The hypothetical amount of stainless steel,
    density 8.00gcm-3 that it would exactly
    counter-balance in air of density 0.0012gcm-3 at
    20oC

48
Handling and care of weights
  • Construction and shape
  • Designed to minimise surface area
  • Convenient to handle
  • Minimum risk of physical damage

49
Handling and care of weights
  • Primary standards are cylindrical
  • Laboratory weights Knob or cylindrical
  • Flat or concave base?
  • OIML recommends slight concave

50
Handling and care of weights
  • Weight Calibration Laboratories store weights
    under a Glass Dome
  • E2 and F1 store in Boxes supplied
  • Oak boxes can be acidic
  • Suitable lining material
  • Free from fibres

51
Handling and care of weights
  • Use lifting devices
  • Plastic forks
  • Tipped forceps keep clean!
  • Cotton or chamois gloves

52
Handling and care of weights
  • Remove dust with camel hair brush
  • Never touch weights
  • Fingerprints are acidic and greasy
  • Clean weights with cotton or chamois
  • Alcohol or steam cleaning removes absorption layer

53
Handling and care of weights
  • Weights become heavier with depositions
  • Weights become lighter with wear and tear
  • Regular calibration and cleaning recommended

54
Handling and care of weights
  • E1 and E2 intervals not exceeding 2 years
  • F1 every year
  • Review after some history
  • Maximum change one half to one third uncertainty

55
Handling and care of weights
  • Calibration of weights
  • Weights examined and cleaned before calibration
  • Weights must be acclimatised prior to calibration

56
Handling and care of weights
  • Weights checked for magnetic susceptibility
    surface finish
  • In some cases density
  • Calibration made according to mass comparison
    method

57
Calibration of Laboratory Balances
  • What is the difference between Calibration and
    adjustment ?

58
Calibration of Laboratory Balances
  • Calibration determines the relationship between
    displayed values and mass of a certified standard
    No intervention takes place
  • Adjustment reduces any deviation to an acceptable
    minimum

59
Calibration of Laboratory Balances
Calibration test with 10g weight
60
Adjustment of a laboratory balance
61
Calibrating Laboratory Balances
  • Frequency -depends influence of observed error
    to the experiment or manufacturing process
  • Daily or before use - using a single or small
    number of weights
  • Full Calibration - As per your SOP Once
    or twice a year including linearity,
    eccentric loading repeatability test

62
How to Adjust Laboratory Balances
Calibrating Laboratory Balances
  • Adjustment -Usually a fixed single point
  • Some balances can select variable points
  • Some balances allow input of certified mass the
    of calibration weight
  • Some balances have internal weights of either the
    nominal value or may be proportional

63
How to Fully Calibrate Laboratory Balances
Full Calibration of Laboratory Balances
  • Usually by a competent third party
  • Sometimes the manufacturer
  • Some small agents can seem cheaper
  • ISO 9000 (ISO 2000 soon)
  • UKAS not always essential

64
How to Fully Calibrate Laboratory Balances
Calibrating Laboratory Balances
  • The balance must be equilibrated to ambient
    conditions and at operating temperature
  • (Adjust the balance with internal weight)
  • Check the entire weighing range for departures
    from linearity 6-10 equally spaced points

65
How to Fully Calibrate Laboratory Balances
Calibrating Laboratory Balances
  • Repeatability test
  • 6-10 measurements the calculate the SD
  • Off Centre load test (at half load)
  • Hysterisis test
  • 0.00g 500.00g 1000.00g

66
Calibration Records to be kept
  • Description and unique ID of Balance
  • Calibration results
  • Source of Calibration used
  • Service/Maintenance Log

67
Calibration Records to be kept
  • Error limits
  • Any limitations of use
  • Responsible person(s)

68
USP Measurement to 0.1 max Uncertainty
  • United States Pharmacopoeia
  • Implemented by the FDA Food and Drugs
    Administration

69
USP Measurement to to 0.1 max Uncertainty
  • Pharmaceutical Laboratories
  • All measurements to be made with intended
    accuracy
  • 0.1 maximum uncertainty

70
What is Uncertainty?
  • Sum of systematic and random errors
  • Systematic errors- from the balance
  • Random Errors- from operators, and the
    environment,

71
Errors
  • Random Errors
  • Operators
  • Off Centre Loading
  • Occasional Poor conditions
  • Occasional Drafts
  • Occasional Vibration

72
Errors
  • Systematic Errors
  • Inherent performance flaws
  • Errors in Calibration
  • Temperature change

73
What is Uncertainty?
  • Measured mass 20.0000g
  • Determined Uncertainty 0.0003g
  • Result is likely to lie between 19.9997
    and 20.0003g

74
Measurement to 0.1 max Uncertainty
  • According to USP25 section 41
  • Maximum of 0.1 uncertainty in any weighing

75
Measurement to 0.1 max Uncertainty
  • For USP Uncertainty is accepted as equal to 3
    times the determined SD (In the place of
    use)

76
Measurements to 0.1 max Uncertainty
  • To determine if balance is acceptable for 300mg
  • Standard deviation 0.1mg
  • Uncertainty 0.1 x 3
  • Uncertainty 0.3mg

77
Measurements to 0.1 max Uncertainty
  • The Question is
  • 0.3 mg lt (or equal to) 0.1 of 300mg

78
Measurements to 0.1 max Uncertainty
USP statement SD /sample weight 0.001 0.3/300
0.001
79
USP Minimum Weight to 0.1 max Uncertainty
  • Even easier
  • Minimum weight is calculated
  • Measured SD x 3 x 1000
  • 0.1mg x 3 x 1000
  • 300mg

80
Typical theoretical minimum weights
Readability
Typical Minimum weight
  • 1mg balance 3000mg
  • 0.1mg balance 300mg
  • 0.01mg balance 45mg
  • 1µg balance 3mg

81
Determination of minimum weight
82
USP Minimum Weight to 0.1 max Uncertainty
  • Common questions
  • Can I add the weight of the container
  • Do I test with the actual weight of sample
  • Do I test with a tare value
  • What if I obtain a fluke SD

83
USP Minimum Weight to 0.1 max Uncertainty
  • What is uncertainty?
  • Sum of Random Systematic errors
  • So what is this 3x SD nonsense!

84
Determination of Uncertainty
  • Remember from before
  • Statistically 68 results one S
  • Statistically 95 results two S

85
Determination of Uncertainty
  • Maximum uncertainty u is defined as 2S
  • 95 results lies within 2S

86
Determination of Uncertainty with 10g sample
  • Reproducibility 0.07mg
  • Temp drift 5C
  • 10g x 1 x 10-6 x 5C 0.05mg
  • Max linearity 0.15mg
  • E2 calibration error 0.015mg
  • (200g max 0.3mg)

87
Determination of Uncertainty with 10g sample
  • Density is 2gcm-3 with 20 uncertainty
  • Difference due to air buoyancy 2.25mg
  • 2.25mg with u of 20 0.45mg

88
Determination of Uncertainty with 10g sample
89
Determination of Uncertainty with 10g sample
mg
90
Determination of Uncertainty with 10g sample
  • We can now say
  • 10.0000 0.05mg with 95 confidence

91
Setting pass fail limits
  • You can determine what is possible from your
    balance
  • You have a measured value for your weight
  • Set limits in accordance with tolerable error in
    your assays

92
Summary and Open Question Session
What about balances and 21CFR part 11?
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