Post on 07-Aug-2020
Introduction: In 2015, the International Organization for Standardization (ISO) published a new document, ISO IWA 15, which describes standardized ways of determining and reporting the volumetric performance of automated liquid handling systems (ALHS).
A. Bjoern Carle, PhDGeorge Rodrigues, PhD
Volumetric performance assessment of automated liquid handling systems with ISO IWA 15
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Figure 1: While ISO standards exist for the calibration of volumetric glassware (ISO 4787) and handheld pipettes (ISO 8655), ISO IWA 15 addresses the need for a global document addressing volumetric performance of automated liquid handling systems.
mLµL
nL
Mechanicalsingle and multi-channel
pipettes
Acoustic dispensing systems
Automated pipetting and dispensing systems
Picoliter dispensing systems
pL
ISO 4787 ISO 8655 ISO IWA 15
Evol
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n of
Liq
uid
Han
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Volumetric and Mohr pipettes (Class A glassware)
1900’s 2015
Figure 2: Standardized volumetric performance assessment improves harmony across liquid handling platforms and geographic regions.
Acknowledgements The following organizations participated in development of ISO IWA 15:Agilent Technologies, Inc.Analytik Jena AGArtel, Inc.Brand GmbH & Co. KGEppendorf AGGilson, Inc.Hamilton Bonaduz AGIntegra Biosciences AGMettler-Toledo Ltd.Sartorius AGTecan Schweiz AGThermo Fisher Scientific OyUniversity of Freiburg (IMTEK)
Review and helpful suggestions were provided by:British Columbia Genome Sciences CenterHinsdale Pathology AssociatesMerck Research LaboratoriesNational Virus Reference Laboratory, University College of DublinNorth Carolina State University (BETEC)
Contents of ISO IWA 15 Terminology: 50 definitionsOperation of ALHS: Environmental conditions, acceptance testing, user testing Volumetric Performance: Indexing to track data, descriptive statistics
Test Methods: Photometric, weighing, and other methodsSpecifications: Information to be provided as part of performance specification
Reporting of Results: Test reports and calibration certificates Applications of Descriptive Statistics: Four examplesBibliography: 41 references
ISO IWA 15 consensus document developed under the direction of ISO/TC 48
Publish ISO IWA 15
Future work proposed by participants
ISO/TC 48/WG 04 to lead suggestedtechnical projects
Collaboration with measurement research groups
and projects
Series of ISO standards to be developed
Need for ALHS standardization identifiedISO IWA 15 project initiated
Example 18 channel device, L = 8one single run, M = 112 replicates per channel, N = 12measured in one 96 well plate
Form. 1 Form. 3 Form. 7Channel 1 2 3 4 5 6 7 8 9 10 11 12 V(l) e S(l) CV(l)
l = 1 A 97.87 97.72 98.33 98.99 98.79 97.98 98.43 99.32 95.69 99.46 99.23 97.59 98.28 -‐‑1.72% 1.06%l = 2 B 97.60 99.53 98.27 99.98 98.44 100.42 100.28 98.54 97.37 100.84 99.95 102.07 99.44 -‐‑0.56% 1.42%l = 3 C 98.23 96.62 95.95 96.14 98.24 96.79 97.77 97.93 98.31 96.28 96.99 97.53 97.23 -‐‑2.77% 0.90%l = 4 D 102.49 99.09 100.74 100.41 101.02 100.15 100.12 100.53 102.11 99.94 99.19 102.36 100.68 0.68% 1.13%l = 5 E 97.31 96.41 98.07 97.97 96.73 99.27 99.13 98.58 96.93 98.30 97.35 98.31 97.86 -‐‑2.14% 0.94%l = 6 F 96.53 96.35 97.54 95.95 95.55 97.79 97.99 97.48 98.87 98.62 97.42 97.65 97.31 -‐‑2.69% 1.05%l = 7 G 97.11 97.13 99.12 97.16 96.53 97.10 98.15 97.14 99.45 97.33 98.16 98.05 97.70 -‐‑2.30% 0.91%l = 8 H 97.86 95.60 98.50 99.43 98.56 98.37 97.11 98.53 97.35 97.47 97.78 97.57 97.84 -‐‑2.16% 0.99%
max e S(l) 0.68%
Run Order Statistics min e S(l) -‐‑2.77%
n → 1 2 3 4 5 6 7 8 9 10 11 12 max CV(l) 1.42%
Form. 9 V(n) 98.13 97.30 98.32 98.25 97.98 98.48 98.62 98.50 98.26 98.53 98.26 98.89
Form. 3 e S(n) -‐‑1.87% -‐‑2.70% -‐‑1.68% -‐‑1.75% -‐‑2.02% -‐‑1.52% -‐‑1.38% -‐‑1.50% -‐‑1.74% -‐‑1.47% -‐‑1.74% -‐‑1.11%
Form. 11 CV(n) 1.88% 1.42% 1.38% 1.75% 1.73% 1.36% 1.14% 1.09% 1.99% 1.53% 1.09% 2.09%
Form. 14
Grand Avg Form. 12 CVC2C
V GA 98.29 1.21%
Overall CV Form. 13
CVOA 1.53%
Figure A.4
Channel Statistics
Overall Statistics
Figure 3: Accurate results are achieved by improving both precision and trueness .
Improving AccuracyDecreasing Uncertainty
Improving PrecisionDecreasing Random Errors
Impr
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Err
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Example 1: Test design and statistical calculations In this example an 8 channel liquid handling system is used to fill a 96 well plate with 100 µL per well. The delivered volume is measured in each well, and descriptive statistics are calculated. The Formula references are highlighted in green (e.g., Form. 14) and each formula is described in detail within ISO IWA 15. This figure corresponds to Figure A.4 in ISO IWA 15. Copyright remains with ISO.
ISO IWA 15 applies current definitions from the international vocabulary of metrology (VIM) and adapts them for the specific case of automated liquid handling systems. This figure shows the relationships between three conceptual terms (accuracy, precision and trueness) along with quantifiable values (uncertainty, random error and systematic error). Figure 3 is adapted from ISO IWA 15, and a description of all 50 terms is contained in that document. Copyright remains with ISO.
Example 2: Updated terminology Future Work
Literature Cited1. ISO 4787:2010 Laboratory glassware - Volumetric instruments - Methods for testing of capacity and for use.
2. ISO 8655 1:2002, Piston-operated volumetric apparatus - Parts 1 - 7.
3. ISO IWA 15:2015 Specification and method for the determination of volumetric performance of automated liquid handling systems.
Contact InformationThe authors welcome inquiries and can be reached directly at the following email addresses:Dr. George Rodrigues: grodrigues@artel-usa.comDr. A. Bjoern Carle: bcarle@artel-usa.com
These three documents are available for purchase at the ISO webstore www.ISO.org/ISO/store.htm
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