Article Text

Aseptic addition method for Lactobacillus casei assay of folate activity in human serum
1. Victor Herbert
1. Department of Haematology, The Mount Sinai Hospital, New York, U.S.A.

## Abstract

An aseptic addition' method is described for microbiological assay with Lactobacillis casei of folate activity in human serum. It has the following advantages over the previously reported standard' method. 1 The manipulations involved in the assay are halved, by deleting autoclaving of serum in buffers. 2 The use of 1 g.% ascorbate better preserves serum folates than the lower amounts of ascorbate which are the maximum quantities usable in the standard methods. 3 Only 0·3 ml. of serum is required (0·1 ml. for one sample; 0·2 ml. for its duplicate).

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