รายละเอียดเอกสาร

The beet pulp sample is preferably ashed by one of the methods recommended for the determination of sulphated ash or crude ash (see Method GS8-6 and GS8-10), the ash is boiled in hydrochloric acid and the insoluble residue filtered and weighed. The calcium is precipitated from the filtrate as calcium oxalate, the precipitate is dissolved in sulphuric acid and the oxalic acid which forms is titrated with a solution of potassium permanganate. The sodium and potassium contents in the filtrate are determined by flame photometry in the presence of caesium chloride and aluminium nitrate; the addition of these substances largely eliminates the effects of interfering elements. The method, derived from the First Commission Directive of the European Union, makes it possible to determine the calcium, potassium and sodium content and the level of mineral substances which are insoluble in hydrochloric acid in dried beet pulp. It is necessary to carry out preliminary drying when dealing with pressed pulp which has a high moisture content. These methods were tested but the precisions obtained were not entirely satisfactory. The Accepted status means that they are suitable for process control in factories.