A sinking fund established by any code county to provide for the payment of the principal of or interest on any bonds issued by the code county pursuant to the provisions of this subtitle shall not be invested by the fiscal officer of the county having custody of the sinking fund except in the manner prescribed by §§ 6 and 7 of Article 31 of this Code. Any fiscal officer having custody of the proceeds of sale of the bonds may invest the proceeds, pending the expenditure thereof, in the manner and pursuant to the provisions of § 22 of Article 95 of this Code.