Preparation of diazotized polystyrene latex and its use in agglutination assays

The preparation of this immunological latex consisted of the following steps: the synthesis of polystyrene, polynitrostyrene, polyaminostyrene and polystyrene diazonium salt latex. The quantities of emulsifier and initiator used in the synthesis of the polystyrene latex were much larger than those used in the conventional method. Reduction of the polynitrostyrene latex involved adding latex dropwise to a large excess of 6% sodium hydrosulphite-2 N potassium hydroxide solution with sodium lauryl benzene sulphonate as an emulsifier. When the mixture was heated at 70 degrees C for 4 h, the emulsion of polyaminostyrene was diazotized. The polystyrene diazonium salt latex obtained was capable of combining with 20-40% by weight of antibody protein. The immunopolystyrene diazonium latex reagents showed a positive agglutination reaction of 78-91% when mixed with serum from patients with leptospirosis and two other infectious diseases. The test, which can be completed within 3 min has been used to assay over 1200 patient samples.