ANALISIS NOx DI UDARA SECARA SPEKTROFOTOMETRI UV-VIS DENGAN PEREAKSI PABA DAN NEDA

FRANSISCA DITAWATI N, Drs. Roto, M.Eng., Ph.D.; Prof. Drs. Mudasir, M.Eng., Ph.D.

2017 | Tesis | S2 Ilmu Kimia

Analisis nitrogen oksida (NOx) di udara secara spektrofotometri Ultraviolet-Visible (UV-Vis) telah dilakukan. Penggantian senyawa sulfanilamida pada metode baku dengan asam p-aminobenzoat (PABA) dimaksudkan untuk mengurangi efek toksik dan karsinogenik. Penelitian ini bertujuan untuk mendapatkan kondisi optimum analisis NOx menggunakan pereaksi PABA dan N-(1-naftil) etilendiamina dihidroklorida (NEDA) melalui reaksi diazotasi dan memenuhi syarat validasi metode serta mengaplikasikan metode tersebut untuk menganalisis NOx di udara. NOx dijerap menggunakan larutan basa membentuk nitrit dan nitrat. Nitrat direduksi menjadi nitrit menggunakan serbuk Zn. Hasil penelitian menunjukkan bahwa senyawa azo mempunyai panjang gelombang maksimum 546 nm dan stabil selama 30-55 menit. Hasil validasi menunjukkan linieritas kurva kalibrasi nitrit dan nitrat dengan R2 = 0,9993 pada rentang 0-0,6228 ppm (v/v) dan nilai absorptivitas molar sebesar 6,15 x 104 L mol-1 cm-1 untuk nitrit dan 5,51 x 104 L mol-1 cm-1 untuk nitrat. Nilai batas deteksi NO2 sebesar 1,295 x 10-3 ppm (v/v) dengan relative standard deviation (RSD) sebesar 1,53%. Persentase perolehan kembali analisis nitrit dan nitrat masing-masing 80,0%-97,8% dan 93,0%-102,1%. Konsentrasi NOx di udara memenuhi baku mutu yakni 230 mikrogram/Nm3. Metode ini dapat diaplikasikan dalam penentuan NOx di udara.

Analysis of nitrogen oxide (NOx) in the atmosphere by Ultraviolet-Visible (UV-Vis) spectrophotometry has been studied. The replacement of sulfanilamide in standard methods by p-aminobenzoic acid (PABA) is intended to reduce the use of toxic and carcinogenic effects of sulfanilamide. The aims of this research were to get optimum condition for NOx analysis using diazotation reaction between PABA and N-(1-naphthyl) ethylenediamine dihydrochloride (NEDA), to validate the method and to apply it for NOx analysis in the atmosphere. After trapping by alkaline solution, NOx in the atmosphere was converted to the form of nitrite and nitrate. Nitrate was first reduced with Zn. The result showed that azo compound had maximum wavelength at 546 nm and was stable for 30-55 minutes. The result of validation showed linearity of nitrite and nitrate standard solution with R2 = 0.9993 in range from 0-0.6228 ppm (v/v) with molar absorptivity 6.15 x 104 L mol-1 cm-1 for nitrite and 5.51 x 104 L mol-1 cm-1 for nitrate, respectively. The NO2 had limit detection of 1,295 x 10-3 ppm (v/v) with relative standard deviation (RSD) of 1.53%. The percent recovery of nitrite and nitrate were 80.0%-97.8% and 93.0%-102.1%, respectively. The NOx concentration in the air meets the standard air quality of 230 mikrogram/Nm3. This method can be applied to the determination of NOx in the atmosphere.

Kata Kunci : NOx, nitrit, nitrat, spektrofotometri UV-Vis, asam p-aminobenzoat