Nitrofurantoin estimation in urine with the aid of chromatography.

HE DETERMINATION OF NITROFTJRANTOIN concentration in the urine of patients receiving Furadantin#{174} [N-(5-nitro-2-furfurylidene)-1-aminohydantoin] for the therapy of urinary tract infections may be desirable for establishing the suitable dosage schedules. The present paper describes a chromatographic method, adapted from previous work at this laboratory (1), for separating interfering substances from Furadantin so that this compound may be determined colorimetrically or spectrophotometrically. Without some procedure for the separation and purification of the nitrofurans, spectrophotometric methods (2) applied to urine are subject to large errors because of the unavailability of true control urines. This is particularly true in the case of abnormal clinical urines where blood, excessive bile pigments, or medication may be present. The colorimetric method for Furadantin (3) cannot be used on untreated urine samples due to the presence of interfering materials. Furadantin concentrations as low as 1 or 2 mg. per 100 ml. can be determined by the chromatographic method to be described.