http://www.legislation.gov.uk/nisr/1991/540/schedule/2/part/II/crossheading/determination-of-boron-titrimetric-methodn2/paragraph/3.8/madeThe Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1991Local GovernmentGovernment Printer for Northern Ireland2016-09-06AGRICULTURESCHEDULE 2METHODS OF ANALYSISPART II9a.DETERMINATION OF BORON — TITRIMETRIC METHODREAGENTS3.8Sodium hydroxide, 0.05 N solution, carbonate free.