N.C. Gen. Stat. § 119-46
The Secretary of Revenue is hereby authorized to fix and collect such charges as he may deem adequate and reasonable for any analysis made by the Gasoline and Oil Inspection Division of any sample submitted by any person, firm, association or corporation other than samples submitted by the gasoline and oil inspectors in the performance of the duties required of said inspectors under this Article: Provided, however, that no charge shall be made for the analysis of any sample submitted by any municipal, county, State or federal official when the results of such analyses are necessary for the performance of his official duties. All moneys collected for such analyses shall be paid into the State treasury to the credit of the Gasoline and Oil Inspection Fund.
N.C. Gen. Stat. § 119-46