SEQUENTIAL INJECTION-FLOW REVERSAL MIXING (SI-FRM) UNTUK PENENTUAN KREATININ DALAM URIN

Jumlah kreatinin yang diekskresikan melalui urin menunjukkan keadaan ginjal seseorang. Dalam penelitian ini, dikembangkan metode untuk penentuan kreatinin secara otomatis yaitu sequential injection-flow reversal mixing (SI-FRM). Pendeteksian kreatinin didasarkan pada pembentukan senyawa berwarna (merah-orange) yang dihasilkan dari reaksi antara kreatinin dan asam pikrat dalam suasana basa dan diukur pada panjang gelombang 530 nm. Reaksi pembentukan senyawa kreatinin-pikrat dilakukan melalui pembentukan segmen antara sampel dan reagen di-holding coil dan selanjutnya dilakukan proses flow reversal di-mixing coil. Parameter-parameter yang mempengaruhi metode ini diuji secara detail. Hasil penelitian menunjukkan bahwa kondisi optimum pengukuran kreatinin yaitu menggunakan konsentrasi asam pikrat 0,035 M dan NaOH 3,5%, laju alir flow reversal 5 µL/detik, laju alir produk reaksi 20 µL/detik, jumlah flow reversal empat kali dan menggunakan tiga segmen (pikrat-kreatinin-pikrat) dengan masing-masing volume segmen 100 µL. Metode SI-FRM ini telah diaplikasikan langsung untuk penentuan kadar kreatinin dalam urin dengan limit deteksi 1,7 µg/g. The amount of creatinine excreted in urine indicates kidney condition. In this experiment, the automatic determination method of determining creatinine was developed by using sequential injection-flow reversal mixing (SI-FRM). The detection of creatinine is based on the formation of a colored product (red-orange) yielded from the reaction of creatinine with picrate at alkaline medium. The absorbance is measured at wavelength of 530 nm.  The formation of creatinine-picrate complex is performed through the segment formation between sample and reagent in the holding coil and then flow reversal process in the mixing coil of SI-FRM. Several parameters affecting to this method are investigated in detail. The results show that the optimum concentrations of picric acid and NaOH are 0.035 M and 3.5%, respectively. Other optimized conditions, such as the flow reversal rate of there 5 µL/s, flow rate of product of 20 µL/s, amount of flow reversal process of four times, and segment amount of three (picrate-creatinine -picrate) with each volume of 100 µL, were obtained. This method is successfully applied to the determination of creatinine in urine with the detection limit of 1.7 µg/g.