Combined compounds functionality is designed to allow automatic adding of concentrations of specified compounds.  For example it could be specified that TPH ranges C6-C10, C11-C14,C15-28,C29-36 be automatically added together to give C6-36.

Compounds that are to be combined are entered into the reference table zRef_Combine_Compounds (select Import - Data Tables - zRef_Combine_Compounds to generate an import template).  The compounds to be combined are entered with the combined compound name as below.

All names must be valid names in the Chemistry Lookup Table.  Compound names that don't match can be corrected by clicking the "Get ChemCodes" button in the Import Template and assigning the correct name.  A weight can be applied to each compound if necessary.  A weight of 1 is used by default.

Compounds are added together using a multiplier for non-detects.  This can be specified under Setup - Chemistry - Combined Compounds.   If a multiplier of 1 is used, and all results are non detects the sum will be shown as "<" the sum.  If another multiplier (such as 0.5) is used the result is an estimate (so is not displayed as less than that estimate).