PRESERVATION METHOD OF WASTEWATER SAMPLES AND STORAGE TIME FOR ANALYSIS OF NITRITE AND NITRATE LEVELS Sutanto1), Mayra Subhiani Suryaningrat2), Fitri Hanifah3), Yulian Syahputri4)
1) dan 4). FMIPA Universitas Pakuan, Jalan Pakuan, Ciheuleut, Kota Bogor
2). PT ALS , Sentul Kabupaten Bogor
3). Seameo Biotrop, Jl Raya Wangun, Kota Bogor
Abstract
Wastewater samples for analysis of nitrite and nitrate levels, are unstable due to the nitrification process, samples must be analyzed immediately, the APHA recommendation storage time is only 48 hours at -6oC. The location of the sample with the remote laboratory and the large number of samples that must be handled by the testing laboratory often require sample storage times beyond the APHA recommendations. This study examines various storage methods to obtain storage methods that produce shelf-life exceeding APHA recommendations. The research was carried out in two stages, the first stage was to prove the recommended storage method of APHA, namely without preservatives and preservatives H2SO4 and HCl (up to pH <2), each stored at 3 temperatures of 4, 25 and 32 oC, observed levels of nitrite, ammonia and nitrate for 10 days. The second stage was preservation of samples with various concentrations of amoxicillin preservative, stored at 4oC and 25oC in two different types of containers. The results of the first stage showed that the best storage was without preservatives, at 4 oC, stable nitrite levels (90-110% recovery) for a maximum of 3 days, and nitrate stable for 5 days. The results of the second stage of the experiment showed that the best storage was at 4oC, with 0.3 ppm amoxicillin as preservative, the first-order nitrite degradation constant was 0.0008 (mg/L)/hour and stable nitrite levels up to 130 hours or 5 days, nitrate levels stable for up to 10 days.
