Sartorius Weighing Seminars Qualified Weighing in Pharmaceutical - - PowerPoint PPT Presentation

Sartorius Weighing Seminars

Qualified Weighing in Pharmaceutical Labs

Regulations and Procedures to ensure best Weighing Accuracy in your Laboratory

• Qualified weighing, Avoid errors – and understand their daily impact
• n your weighing accuracy

Qualified weighing requires:

• Trained competent personnel
• Defined appropriate equipment and

conditions

• Testing facility designed to minimise

problems

3

• 5. Februar 2013

Qualified weighing requires:

• Regular calibration of measuring

equipment

• According to accepted methods
• Use of Appropriate test & reference

standards – Calibration Weights

4

• 5. Februar 2013

Qualified weighing requires you to:

• Keep your balance clean
• Position the balance on firm surface
• Level the balance
• Protect the balance from drafts
• Especially air conditioning
• Never position in direct sunlight
• Never position in direct sunlight
• Keep well away from all heat sources
• 5. Februar 2013

5

Avoid errors The correct place of installation?

• Mechanically and climatically stable

−

stable temperature and humidity

−

better on the first floor than on upper floors

• No vibrations

−

especially low frequencies

Air condition Open doors Open windows Sunlight Air draft

−

especially low frequencies < 10Hz should be avoided

−

better to be closer to a wall, than in the middle of the room

• Avoid installation in the exhaust area
• f an air conditioner (disturbances and

temperature)

• 5. Februar 2013

6

draft unstable table Humidity Hustle and Bustle Vibrations

Avoid errors The correct place of installation?

• Not near to a window, no direct sunlight

− avoid infrared radiation;

no direct light e.g.... a desk lamp

• Quiet place without hustle and bustle

Air condition Open doors Open windows Sunlight Air draft

• 5. Februar 2013

7

draft unstable table Humidity Hustle and Bustle Vibrations

Avoid errors Electrostatic charges

• Electrostatic charges create an acting force in addition to the weight of the sample

and container.

− This force is not constant. It’s influenced by humidity, the user and handling of

samples and containers.

− The weight readout drifts in one direction. Values are non-repeatable.

• 5. Februar 2013

8

• Static electricity occurs on:

− substances or containers with low electrical conductivity − large surfaces (plastic or glass containers, filters)

• The reasons are:

− internal friction in powders, external friction − transfer of electrical charges by persons − problem increases with decreasing humidity (<40%)

Avoid errors Elimination of electrostatic Charges

Internal solutions:

• Built-in ionizer inside the draft shield of

semi-micro, analytical and 1mg-balances External solutions

• Ionizer cube YIB01
• Ionizer cube YIB01
• Stat Pen YSTP01 for small sample

containers and membrane filters

9

• 5. Februar 2013

Avoid errors Magnetic and magnetisable samples

The problem: Magnetic materials in samples or containers, such as nickel, iron, steel, generate force fields that act against the permanent magnet of the weighing system.

• Weight values are stable, but non-repeatable.
• Different values are displayed depending on the
• Different values are displayed depending on the

position of the sample on the weighing pan. How to avoid:

• Do not weigh with magnetic stirrer inside the vessel
• Perform demagnetization before weighing. Use a

nonmagnetic object to distance the sample from the weighing pan.

• Use Mu-metal (81% Ni and 19% Fe) foil as shielding.
• Use below balance weighing
• 5. Februar 2013

10

Avoid errors Non-level balance

One of the worst errors that occurs during weighing is caused when the balance is unlevel.

• 5. Februar 2013

11

α α α α

400µm

Avoid errors Non-level balance

Example: If the balance is inclined only 400m (Thickness of a business card) on one side an incorrect measurement is produced:

• That means, the mass of 200g is

displayed 0.37mg too low

• The resulting error is greater than the

allowable tolerance of a 200g ± 0.3mg E2 calibration weight for an analytical balance. Error calculation: md = m · cos α = 200g · cos (0,11° ) = 199,99963g

α = arctan (0.4mm/200mm)

∆m = -0.00037g

• 5. Februar 2013

12

α α α α

400µm

Avoid errors – due to changes in regional gravity influenced by changes in elevation and latitude

• Ground floor 200.00000g
• First floor 199.99974g
• Difference 0.00026g
• 5. Februar 2013

13

Avoid errors Balance warm up period

Balances need to be warmed up (after new installation)

• Precision Balances (d >1 mg)
• approx. 30 min
• Analytical Balances (d> 0.1 mg)
• approx. 4 h
• approx. 4 h
• Semimicro Balances (d> 0.01 mg)
• approx. 12 h
• Ultramicro/Micro Balances (d> 0.001 mg)
• approx. 24 h

To avoid subsequent warm up periods :

• do not disconnect from power
• leave balance always in the standby-

mode

• 5. Februar 2013

14

Was passiert wann konkrete Empfehlungen

Avoid errors Critical samples

Hygroscopic substances:

• Moisture absorption of powders

Efflorescent substances

• evaporation from the sample
• both cause a real weight change
• different results when weighing the

sample at different times

• weighing value is drifting

How to avoid?

• use narrow-necked or covered vessels
• stabilise sample humidity in a desiccator
• work quickly
• 5. Februar 2013

15

Bilder Tauschen

Avoid errors Non acclimatized samples and tare containers

Sample containers are very often not sufficiently acclimatised:

• temperature differences between

weighing chamber and sample/sample vessels

• weighing results are varying
• weighing results are varying
• weighing value is drifting:

− sample too cold: “weight increasing” − sample too warm: “weight decreasing”

How to avoid?

• acclimatisation of sample/sample

containers

• place weighing containers and sample

inside weighing chamber before weighing

• 5. Februar 2013

16

Avoid errors Handling of samples, vessels and calibration weights

• handling the sample with hands raises

temperature and causes “gain-weight” effects

• this temperature effect can still be

recognised after 10 minutes

• fingerprints falsify the real mass approx.
• fingerprints falsify the real mass approx.

50 to 100g

• additionally fingerprints can be

hygroscopic

• using the hand inside the draft shield

causes additional turbulence and temperature effects

• weighing values are different, not stable

and drifting

• 5. Februar 2013

17

Avoid errors Handling of samples, vessels and calibration weights

How to avoid?

• never handle the sample without

tweezers or some other suitable gripping device

• always use gloves
• avoid working inside the draft shield, use
• avoid working inside the draft shield, use

a spatula which is long enough to keep the hand outside

• 5. Februar 2013

18

Bilder Tauschen

Avoid errors Filling containers

Ergonomic aspects:

• sometimes it’s difficult to weigh in the

sample into small vessels, flasks or tubes

• the greatest problem is “spilling sample
• n the weighing pan”
• n the weighing pan”
• the sample weight is displayed correctly

but the sample is not inside the container How to avoid:

• Use special vial holder (Q-Grip)
• 5. Februar 2013

19

• Minimum sample weight according to USP

Minimum sample weight according to USP Weighing in the Pharmaceutical Laboratory

USP Minimum Sample Weight Determination

12,6 Kg

• 5. Februar 2013

21

divided by 3!

Minimum sample weight according to USP United States Pharmacopeia – Chapter 41

USP 34 NF Chapter 41 Weights and Balances

• determination of the minimum sample

weight

• the measuring uncertainty must be

known – three times the standard known – three times the standard deviation out of min. 10 replicant weighings

• measuring uncertainty (U) must not

exceed 0.1% of the minimum sample weight (M):

• the factor can be extended up to 0.00149
• 5. Februar 2013

22

001 . M U ≤

U M * 1000 ≤

SD U * 3 =

) 49 ( 001 . M U ≤

Minimum sample weight according to USP United States Pharmacopeia - Interpretation

• the USP demands the practical

determination of the minimum sample weight on site

• sample containers (vessels, flasks, ...)

must be tared

• the smalest minimum sample weight
• the smalest minimum sample weight

is = 1000 digits

• the minimum sample weight is only

applicable for „assays“!!

• 5. Februar 2013

23

Minimum sample weight according to USP

• there are different interpretations of the

USP, Chapter 41

• Sartorius determins if a mass is

applicable

• OTHERS calculates the minimum weight

to measured on the balance

vs

to measured on the balance

• both procedures are globally used
• BUT, important is the interpretation of the

local FDA inspector...

• 5. Februar 2013

24

OTHERS

Minimum sample weight according to USP Sartorius method to determine if appropriate

* 1000 =

OTHERS calculates

• 5. Februar 2013

25

from a Sartorius USP Certificate

= 14 mg

Sartorius has verified a 15mg weight

Minimum sample weight according to USP The problem with the minimum weights...

In pharmaceutical labs in Europe you will find 3 different minimum weights, that should not be mixed up.

• 1. Min. Weight acc. European Guidlines for

Legal Metrology (only Europe)

− Min Weight specification with legal

Example, Semi-Microbalance min acc. EGLM = 1 mg min acc. ISO (1%)

• approx. 10 mg

min acc. USP approx. 20 mg

− Min Weight specification with legal

character – you must not fall below this weight

• 2. Min Weight acc self defined tolerances

− on ISO 17025 based min weight, self

defined, acc internal accuracy demands.

• 3. Min. Weight acc USP

− inspected by FDA – mutual character

in USA and for any manufacturer exporting to US

• 5. Februar 2013

26

min acc. USP approx. 20 mg

Minimum sample weight according to USP Why is it not possible to take the USP min from an ISO17025 certificate?

• ISO17025 measuring uncertainty is

based on double standard deviation (K=2), USP is based on three times SD (K=3)

• ISO 17025 considers more parameters
• ISO 17025 considers more parameters

compared to the USP (e.g. Linearity, weight tolerances, tempeture drift, rounding error).

• 5. Februar 2013

27

DKD USP

Minimum sample weight according to USP My minimum sample weight is 10 mg. Which balance should I use?

• 10 mg is the absolute limit for a 5

decimal balance in “perfect” conditions

• The minimum sample weight is based
• n the reproducibility of a balance and

is significantly influenced by ambient conditions at the place of installation. Recommendation: Use a microbalance with a readability

• f 1 g.
• Specifying minimum weight to the

absolute limit it is not recommended since performance is not guaranteed

• ver a balances complete life time.
• 5. Februar 2013

28

Minimum sample weight according to USP Typical* Minimum Sample Weights achieved by Sartorius Balances

Readability/Balance Type 0.1g 1 g 1 g 10 g Minimum Sample Weight 1 mg 2 – 5 mg 5 – 15 mg 15 – 100 mg 10 g 0.1 mg 1 mg * typical = based on Sartorius experience 15 – 100 mg 100 mg 1 g

• 5. Februar 2013

29

• Qualification of your laboratory balance

Equipment Qualification Validation - Qualification

• Validation ist the documented evidence that a process fulfills the defined needs in

practical use.

• Qualification is the evidence that the equipment is able to fulfill it´s part in this

validated process

• 5. Februar 2013

31

• Therefore a balance is ne´ver validated – it is qualified to be used in a validated

process

Equipment Qualification Any equipment qualification needs 4 steps

DQ = Design Qualification IQ = Installation Qualification Technical specification for equipment (specification meet the user requirements) Equipment is delivered and installed in accordance with the Before Purchasing At

• 5. Februar 2013

32

IQ = Installation Qualification OQ = Operational Qualification PQ = Performance Qualification installed in accordance with the qualified design Test of operational functions Test of specified application Ongoing performance tests and preventive maintenance At installation After installation At regular intervals

Equipment Qualification Design Qualification (DQ)

• DQ is the documented collection of activities that define the functional and
• perational specifications of the instrument and criteria for selection of the vendor,

based on the intended purpose of the instrument

• It documents the design of the system and include :

− Functional specification

• 5. Februar 2013

33

− Functional specification − Technical / performance specification for equipment

• A thoroughly executed DQ ensures that:

− Specification meet the user requirements − Design is compliant with GMP and other regulatory requirements − Details all equipment that must be ordered

Equipment Qualification Installation Qualification (IQ)

• IQ is the documented collection of activities necessary to establish that an

instrument is delivered as specified, is properly installed in the selected environment, and that this environment is suitable for the instrument

• Parts of the IQ

− Comparison of the equipment received with the purchase order

• 5. Februar 2013

34

− Comparison of the equipment received with the purchase order − Equipment check for any damage. − Documentation check for completeness − Installation of hardware − Initial cleaning − SQ-min-Identification

Good to know: Responsibility for IQ lies, as the whole EQ, with the user but activities can be supported and carried out by the vendor.

Equipment Qualification Operational Qualification (OQ)

• OQ is the documented collection of activities necessary to demonstrate that an

instrument will function according to its operational specification in the selected environment

• OQ tests verify that the instrument

− meets manufacturer or users specification

• 5. Februar 2013

35

− meets manufacturer or users specification − operating within established limits and tolerances

• Parts of the OQ

− Basic function check and check if the instrument powers up after it is switched on − Calibration − Operator training

Equipment Qualification Performance Qualification (PQ)

• PQ is the documented collection of activities necessary to demonstrate that an

instrument consistently performs under ‘full operational‘ conditions, and is appropriate for the intended use

• PQ tests using production materials
• 5. Februar 2013

36

• Tests include a condition or set of conditions encompassing upper and lower
• perating limits
• PQ is ongoing

Good to know: PQ is described as a separate activity, for balances it is appropriate to perform it in conjunction with OQ

IQ/OQ-Service

• IQ/OQ documentation is based on a

generic risk analysis

• Documentation consists of the IQ and

OQ planning and of protocols for the IQ and OQ tests

• Documentation supports GLP, GMP and
• Documentation supports GLP, GMP and

FDA guidelines

• Accredited calibration certificates for our

balances

• All documentation could easily be

integrated in existing QM systems

• 5. Februar 2013

37

Equipment Qualification

One main question remains:

• What should be tested during a IQ|OQ?

− Is it important to test the right colour of the equipment housing? − Is it important to test if the right power supply was delivered? − Is it important to issue a calibration certificate?

• 5. Februar 2013

38

− Is it important to issue a calibration certificate?

• How is the scope of test defined?

Other possibilities in the pharmaceutical industry for risk analysis

• Which is the right balance in my process (which measurement uncertainty is

necessary)

• What should be described in an SOP
• How often should the balance be calibrated
• How often is a maintenance needed
• Risk Analysis
• 5. Februar 2013

39

• Risk Analysis

Risk based approach

• Not each and every balance has to be qualified (Impact assessment)
• Not each and every function has to be qualified
• The most important thing is to focus on critical instruments and points

Focus on the critical instruments and critical points

• Reduce time
• 5. Februar 2013

40

• Reduce time
• Reduce costs

Risk based approach

• In August 2002, the FDA announced a significant new initiative that focuses on

critical areas

• The new focus is that a quality management system needs to be based on a risk

management

• 5. Februar 2013

41

What does this mean?

• The idea is to stop the water can principle of validation and qualification

− to focus on critical aspects

• The level of effort, formality and documentation of the quality risk management

process should be commensurate with the level of risk

Risk analysis

• Risk analysis is a methodic approach to define critical parameters of equipment,

systems and processes

• In the regulated industry (GLP and GMP environments), it is used for systematic

identification of potential risks and is a key integral component of quality risk management

• Risk analysis is used as a key element in qualification projects. It helps to assess
• 5. Februar 2013

42

• Risk analysis is used as a key element in qualification projects. It helps to assess

individual project risk, critical functions of equipment and systems and define the scope of equipment qualification

• The basis for the requirement of performing risk analysis is found in ISO/IEC Guide

51:1999 and 73:2002, DIN EN ISO 14971:2000, the GMP Regulations of the FDA (Risk Based Approach) and in ICH (Q9 – Quality Risk Management)

• Risk based approach brings the user in the responsibility to reflect all quality

relevant processes

Risk management

• Increases the understanding of the process
• Brings decisions on a better base
• Helps to establish actions that minimize the risk
• Gives the auditors significant information how a company works
• Provides important arguments why e.g. a calibration is done only once a week
• 5. Februar 2013

43

Risk Evaluation

A risk of a potential failure can be evaluated by the probability of occurrence, the severity and the probability of detection. Risk Priority Number RPN = O x S x D (can vary from 1 to 125)

O = Probability of occurrence S = Severity D = Probability of detection

• 11. August 2009

Seite 4

D = Probability of detection O (occurrence rating): 1= Unlikely 2= Very low 3= Low 4= Moderate 5= Likely/High S (severity rating): 1= No impact 2= Insignificant 3= Moderate impact 4= High impact 5= Catastrophic impact D (detection rating): 1= High 2= Moderate 3= Low 4= Very low 5= Unlikely

Risk Evaluation (Example) What is the risk that the balance is not leveled?

O (occurrence rating): 1= Unlikely 2= Very low 3= Low S (severity rating): 1= No impact 2= Insignificant 3= Moderate impact 4= High impact D (detection rating): 1= High 2= Moderate 3= Low 4= Very low

• 11. August 2009

Seite 4

3= Low 4= Moderate 5= Likely/High 4= High impact 5= Catastrophic impact 4= Very low 5= Unlikely

Risk Priority Number RPN = O x S x D = 4x4x3 = 48

Different kinds of risk analysis

• Failure Mode Effects Analysis (FMEA)
• Hazard Analysis and Critical Control Points (HACCP)
• Ishikawa
• 5. Februar 2013

46

Failure mode and effects analysis (FMEA)

• Originally Developed in the 1940’s for the US military and utilised in the Apollo

space program

• Benefit is to find critical aspects and identify where to focus
• Steps of the FMEA:
• Potential failures (“Failure modes”) are detected
• Failures are analyzed “Effects analysis” (study of the consequences) and prioritized
• 5. Februar 2013

47

• Failures are analyzed “Effects analysis” (study of the consequences) and prioritized

according to how serious their consequences are, how frequently they occur and how easily they can be detected

• Actions are planed to prevent or reduce the severity or likelihood of failures

Failure mode and effects analysis (FMEA)

• Sartorius IQ|OQ Documents are based on a generic risk analysis
• Potential risks that are connected with the installation and operation of a laboratory

balances where evaluated with an FMEA .

• Equipment and application specific risks had not been taken into account.
• 5. Februar 2013

48

Knowledge about possible risks

To evaluate possible risks you have to identify them

• How big is the influence of a non-leveled balance?
• How big is the temperature depending drift of a balance?
• How big is the influence of a non optimized choice of vessel?
• How big is the influence of touching a vessel with bare fingers?
• How big is the influence of touching a vessel with bare fingers?
• How big is the influence a temperature difference between sample vessel and the

temperature inside a draft shield?

Knowledge about possible risks

Once you know about the possible risks your are able to decide

• Is the risk important for my process at all?
• Can I reduce that risk by systems to compensate these effects
• Can I increase the probability of detection by available monitoring systems

Risk analysis Regulatory compliance Choice of best balance Processintegration Calibration weights Installation Maintenance

Let us help you

Advanced

Pharma

Compliance

Page 1

User training Calibration interval Balance-Qualification (IQ/OQ) Warning - and action thresholds Calibration weights Installation Correct weighing

The evaluation tool combines

Risk Analysis Measureme nt process requirement s

Advanced

Pharma

Compliance

Page 3

Expert Input

Certificate These are the

• balance
• accessories
• services
• procedures

you need!

Sartorius weighing specialist

We recommend.. .

Qualified weighing with Sartorius APC

Our weighing specialists will assist you by

• Evaluating your weighing process
• Determining the risks together with you
• Propose a weighing solution consisting out of
• type of balance
• type of balance
• best choice of accessories
• recommendation for calibration weights and calibration cycles
• recommendation for warning and action thresholds

Qualified weighing with Sartorius APC

Qualified weighing with Sartorius APC

This documentation (Risk Analysis) is an essentiell part of your

Design-Qualification

Advanced

Pharma

Compliance

• Monitoring your laboratory balance

Monitoring the balance

Two things are important in daily work with the balance in a pharma lab:

• Monitoring the test equipment –

making sure that the balance always is working within the defined tolerance limits

• Avoiding weighing errors caused by the user, the environmental conditions and the
• 5. Februar 2013

57

• Avoiding weighing errors caused by the user, the environmental conditions and the

sample or sample container influences

Routine testing for constant safety – test equipment monitoring

Every Lab, which is accredited according to ISO/IEC 17025 or works according to the GLP/GMP guidelines must regularly calibrate its testing equipment, and adjust as necessary.

• Minimize the risk of erroneous measurements
• Fulfill the required process accuracy at any time
• 5. Februar 2013

58

• Fulfill the required process accuracy at any time

But, when and how often should calibration/adjustment be carried out on regular basis?

• The length of the inspection interval depends on the risk of weighing, that means:

The customer has to clarify “how critical is the weighing value in the complete process”

• Based on that evaluation „warning levels“ and „action levels“ are determined

Monitoring test equipment– how often ?

Simple rule:

• Daily, weekly or monthly in case the weight values are not critical
• If weighing values are critical in the whole process, than

calibration should be done before every series of measurement

Page 5

Better:

• Dynamic verification and adjustment of intervals based on

calibration results and defined warning and action thresholds

Monitoring test equipment Dynamic verification of calibration intervals

T ime Measuring Value

Upper intervention limit T arget Value Upper warning limit Lower intervention limit Lower warning limit

T ime Measuring Value

Upper intervention limit T arget Value Upper warning limit Lower intervention limit Lower warning limit

Increase Interval Increase Interval T ime Me a s uring V a lue

Upper intervention limit T arget V alue Upper warning limit Lower intervention limit L

• wer warning limit

T ime Me a s uring V a lue

Upper intervention limit T arget V alue Upper warning limit Lower intervention limit L

• wer warning limit

Decreas e Interval Decreas e Interval

case 1: increase intervals case 2: decrease intervals

Page 6

T ime Measuring V alue

Upper intervention limit T arget Value Upper warning limit Lower intervention limit Lower warning limit

T ime Measuring V alue

Upper intervention limit T arget Value Upper warning limit Lower intervention limit Lower warning limit

case 1: increase intervals case 3: call service case 2: decrease intervals

Monitoring test equipment How many and which weights to use ?

Often calibration is done only at one point

• f the whole weighing range.

Better:

• Calibration should be performed at three

prominent points of the characteristic

ed Weighing V alue

Near maximum Working range

ed Weighing V alue

Near maximum Working range

prominent points of the characteristic balance curve

• Near the minimum weight, to fulfill the

regulatory requirements of USP

• In the working range, where the balance

is finally used; typically this is 10 to 20%

• Near the maximum load, because at that

point the absolute error is the highest

• 5. Februar 2013

61

Dis played

Near minimum weight

1 2 3

Dis played

Near minimum weight

1 2 3

Monitoring test equipment The balance is monitoring itself - isoCAL

• Sartorius Cubis and Secura series

balances are designed for Pharmaceutical labs and include functions, which make monitoring easier for the user

• Automatic calibration/adjustment function

isoCAL isoCAL

• isoCAL maintains the accuracy of the

balance within an narrow tolerance band without testing efforts

• 5. Februar 2013

62

It corrects:

• deviations regarding to the sensitivity
• f the balance
• temperature influence

(temperature limits can be set)

• compensates the influence of gravitation

Monitoring test equipment The balance is monitoring itself - isoCAL

• compensates the influence of gravitation

(location, differences in altitude)

• air pressure, air density and humidity

fluctuations (but it‘s not a compensation)

• aging effects of mechanic and electronic
• 5. Februar 2013

63

Model Temperature changes by After a time interval of Ultra-micro, Micro, Semi-micro, Analytical 1mg-precision balances ≥1200g 1.5 ° C 4h 1mg-precision balances ≤1200g 10mg-precision balances ≥4200g 2° C 6h

Monitoring test equipment The balance is monitoring itself - isoCAL

• 5. Februar 2013

64

10mg-precision balances ≥4200g 10mg-precision balances ≤ 4200g 4° C 12h 100mg-precision balances 4° C 24h

The Balance is Monitoring Itself Default parameter settings of isoCAL for Cubis

The parameters can be changed by the user, but only in the direction to smaller values.

• isoCAL has to be checked periodically by performing a calibration with an external

retraceable calibration weight. Best is, to test isoCAL at the same time that the balance is calibrated, given by the defined test interval.

• An external calibration cannot be substituted by an internal calibration/adjustment
• 5. Februar 2013

65

• An external calibration cannot be substituted by an internal calibration/adjustment

function, however it is possible to expand the test intervals.

• isoCAL provides more safety in between the test intervals.

One of the worst errors that occurs during weighing is caused when the balance is unleveled.

Monitoring test equipment The balance is monitoring itself – Q-Level

• 5. Februar 2013

66

α α α α

400µm

Monitoring test equipment The balance is monitoring itself – Q-Level

Example: If the balance is inclined only 400µm ( thickness of a businesscard) on one side an incorrect measurement is produced: md = m · cos α = 200g · cos (0,11°) = 199,99963g

• 5. Februar 2013

67

α α α α

400µm

md = m · cos α = 200g · cos (0,11°) = 199,99963g α = arctan (0.4mm/200mm) ∆m = -0.00037g That means, the mass of 200g is displayed 0.37mg too less The resulting error is greater than the allowable tolerance of a 200g ± 0.3mg E2 calibration weight for an analytical balance.

The automatic, motorized leveling featured

• n Cubis controls that the balance is

correctly leveled and performs the time consuming alignment of the balance. It is activated by pressing a start key or

Monitoring test equipment The balance is monitoring itself – Q-Level

It is activated by pressing a start key or fully automatically in conjunction with the isoCAL function

• 5. Februar 2013

68

For quick determination of the standard deviation to check the repeatability of results Definition

• Repeatability is the ability of the balance to display identical readouts when it is

loaded several times with the same weight under constant ambient conditions.

• The standard deviation for a given number of measurements is used to quantify

the repeatability

Monitoring test equipment The balance is monitoring itself – ReproTEST

• 5. Februar 2013

69

the repeatability

• The “reproTEST” function automatically determines the repeatability of results

(based on 6 individual measurements).

• The balance determines the most important specification in relation to the place
• f installation – the pure performance without user influence.
• However, reproTest is no replacement for an external calibration!
• The user can quickly decide if environmental conditions (air draft, vibrations) have

changed.

Thanks for your attention Thanks for your attention