This code system http://hl7.org/fhir/substance-weight-method defines the following codes:

CodeDisplay
SDS-PAGE SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis)
Calculated calculated
LighScattering light scattering
Viscosity viscosity
GelPermeationCentrifugation gel permeation centrifugation
End-groupAnalysis End-group analysis
End-groupTitration End-group titration
Size-ExclusionChromatography Size-exclusion chromatography
<status value="active"/><experimental value="false"/><date value="2021-01-05T10:01:24+11:00"/><publisher value="HL7 (FHIR Project)"/><contact><telecom><system value="url"/><value value="http://hl7.org/fhir"/></telecom><telecom><system value="email"/><value value="fhir@lists.hl7.org"/></telecom></contact><description value="SubstanceWeightMethod"/><jurisdiction><coding><system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/><code value="001"/><display value="World"/></coding></jurisdiction><caseSensitive value="true"/><valueSet value="http://hl7.org/fhir/ValueSet/substance-weight-method"/><content value="complete"/><concept><code value="SDS-PAGE"/><display value="SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis)"/></concept><concept><code value="Calculated"/><display value="calculated"/></concept><concept><code value="LighScattering"/><display value="light scattering"/></concept><concept><code value="Viscosity"/><display value="viscosity"/></concept><concept><code value="GelPermeationCentrifugation"/><display value="gel permeation centrifugation"/></concept><concept><code value="End-groupAnalysis"/><display value="End-group analysis"/></concept><concept><code value="End-groupTitration"/><display value="End-group titration"/></concept><concept><code value="Size-ExclusionChromatography"/><display value="Size-exclusion chromatography"/></concept></CodeSystem>