Pembuatan dan Pengujian Sampel Kontrol Urea sebagai Jaminan Mutu Internal dalam Analisis Kadar Biuret dan Total Nitrogen pada Pupuk Urea

Abstract

Pengendalian kualitas produk di PT Pupuk Kujang Cikampek dilakukan melalui analisis rutin dengan jaminan mutu internal untuk memastikan keandalan hasil. Penelitian ini bertujuan membuat serta mengevaluasi sampel kontrol (SC) urea berdasarkan uji akurasi, presisi, homogenitas, dan stabilitas, serta konsistensinya terhadap instrumen berbeda merek. Analisis kadar biuret dilakukan dengan metode spektrofotometri, sedangkan total nitrogen (N) dengan metode Kjeldahl. Hasil menunjukkan metode akurat dengan perolehan kembali 99–100% dan sesuai rentang nilai benar bahan acuan KBA. Presisi baik ditunjukkan oleh SBR = 2,7% untuk biuret dan = 1,6% total N. SC urea dinyatakan homogen (Ss = 0,3s) dan stabil (|Xr - Yr| = 0,3s). Nilai properti SC ditetapkan dengan rentang biuret sebesar 1,04–1,16%b/b (SPF 12.13) dan 1,05–1,17%b/b (SPF 12.14), serta total N sebesar 46,05–46,55%b/b (NIT 13.04 dan 15.05). Pemantauan hasil analisis selama 10 minggu menggunakan instrumen berbeda merek menunjukkan hasil konsisten tanpa pelanggaran aturan Westgard pada grafik Levey-Jennings.

Product quality control at PT Pupuk Kujang Cikampek is carried out through routine analysis with internal quality assurance to ensure reliable results. This study aims to develop and evaluate urea control samples (SC) based on accuracy, precision, homogeneity, and stability tests, as well as assess their consistency using instruments of different brands. Biuret content was analyzed using the spectrophotometric method, while total nitrogen (N) was measured using the Kjeldahl method. The results showed accurate methods with recoveries of 99–100% and within the certified reference material KBA range. Good precision was indicated by RSD = 2.7% for biuret and = 1.6% for total N. The SC urea was found to be homogeneous (Ss = 0.3s) and stable (|Xr - Yr| = 0.3s). Property values were set with biuret ranges of 1.04–1.16%w/w (SPF 12.13) and 1.05–1.17%w/w (SPF 12.14), and total N of 46.05–46.55%w/w (NIT 13.04 and 15.05). Analysis monitoring over 10 weeks using different branded instruments showed consistent results with no Westgard rule violations on the Levey-Jennings chart.