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"ABSTRAKPada pasien sakit kritis, salah satu faktor yang berhubungan dengan angka mortalitas adalah hilangnya protein tubuh, yang digambarkan dengan imbang nitrogen negatif. Imbang nitrogen negatif merupakan akibat penyakit pasien tanpa diimbangi asupan energi dan protein yang adekuat. Berdasarkan hal tersebut, maka dilakukan penelitian ini, yang bertujuan untuk mengetahui korelasi antara asupan energi dan imbang nitrogen pasien sakit kritis di Intensive Care Unit (ICU) dewasa Rumah Sakit Umum Pusat Nasional Cipto Mangunkusumo (RSUPNCM). Metode penelitian yang digunakan adalah studi potong lintang dengan cara mendapatkan sampel consecutive sampling. Kriteria penerimaan adalah pasien ICU dewasa RSUPNCM Jakarta, laki-laki atau perempuan, berusia 20-79 tahun, dan bersedia mengikuti penelitian. Kriteria penolakan adalah pasien yang mengalami gangguan fungsi ginjal atau gangguan fungsi hati. Kriteria pengeluaran adalah pasien tidak dapat mengikuti penelitian sampai selesai atau data tidak lengkap. Data penelitian meliputi asupan energi dan nitrogen, nitrogen urea urin (NUU), serta imbang nitrogen dalam 24 jam awal perawatan. Hasil penelitian menunjukkan pada 30 subyek penelitian terdapat rerata asupan energi 56,3+33,9 % berdasarkan panduan ESPEN. Rerata asupan nitrogen, NUU dan imbang nitrogen masing-masing adalah 3,8+2,7 g, 8,3+4,4 g, dan -8,5+5,5 g. Terdapat korelasi positif kuat bermakna antara asupan energi dan imbang nitrogen, r=0,6, p<0,01. Kesimpulan penelitian ini adalah semakin kurang asupan energi, maka imbang nitrogen akan semakin negatif.

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ABSTRACTHigh protein loss is an important factor in critically ill patients mortality, that is indicated by negative nitrogen balance. Negative nitrogen balance is the result of urinary urea nitrogen (UUN), caused by the severity of the disease, compared to energy and protein intake. This study had been completed, which aimed to determine the correlation between energy intake and nitrogen balance of critically ill patients in adults Intensive Care Unit (ICU) Ciptomangunkusumo general hospital. The method of this study was a cross sectional with consecutive sampling. Inclusion criteria were patients admitted to ICU, aged 20-79 years, and agreed to join this study. Exclusion criteria were patients with kidney or liver diseases. Drop out criteria were patiens who did not complete the study or have complete data. Data collected were energy and nitrogen intake, UUN, nitrogen balance during first 24 hours. There were 30 patients who participated in this study. Energy intake mean was 56,3+33,9 %, based on ESPEN guideline. Mean of nitrogen intake, UUN, and nitrogen balance were 3,8+2,7 g, 8,3+4,4 g, and -8,5+5,5 g, respectively. The correlation between energy intake and nitrogen balance was significantly strong positive correlated. The conclusion of this study is the lower energy intake, the more negative nitrogen balance."

"Latar Belakang: Penyebab tertinggi kedua kematian di ICU adalah penyakit infeksi, yang ditandai dengan keseimbangan nitrogen negatif. Asupan nutrisi meningkatkan sintesis protein dan meningkatkan keseimbangan nitrogen negatif tersebut. Penelitian ini bertujuan untuk mengetahui perbedaan imbang nitrogen dan perbaikan infeksi pada pasien sakit kritis. Metode: Penelitian ini merupakan penelitian dengan rancangan kohort prospektif. Pengambilan subjek dilaksanakan di ruang ICU, high care unit, dan ruang rawat non sakit kritis di RSCM dan RSUI. Karakteristik subjek penelitian berupa usia, jenis kelamin, status gizi, diagnosis penyakit utama, penyakit komorbid, penggunaan antibiotik, asupan energi dan protein. Analisis beda rerata dilakukan untuk menilai selisih imbang nitrogen dengan perbaikan infeksi pada pasien sakit kritis dengan uji Mann-Whitney. Hasil: Sebanyak 42 subjek merupakan pasien dewasa sakit kritis di ICU, sebagian besar adalah laki-laki sebanyak 27 orang (64,3%). Median usia subjek penelitian ini adalah 47 (19-60) tahun dengan berat badan (BB) kurang berjumlah 14 orang (33,3%). Rerata BB dan tinggi badan secara berturut-turut adalah sebesar 57,29±17,73 dan 162,6±7,93. Subjek penelitian terbanyak tidak memiliki komorbid dengan jumlah 20 orang (47,6%). Seluruh subjek penelitian mendapatkan terapi antibiotik 42 orang (100%). Asupan protein awal adalah 0,39 (0,0-1,1) kkal/kgBB dan asupan protein akhir adalah 0,72±0,34 kkal/kgBB. Imbang nitrogen 48 jam pertama di ICU adalah -6,84 (-25,4; 1,6), rerata imbang nitrogen hari ke-7 adalah -5±4,09 dengan selisih imbang nitrogen adalah 2,4 (-11,8; 27,8). Selisih imbang nitrogen pasien yang mengalami perbaikan infeksi adalah 3,97 (-11,8; 14,5) (p <0,05), dengan pasien yang mengalami perbaikan infeksi adalah 30 orang (71,4%). Kesimpulan: Perbaikan imbang nitrogen secara bermakna memperbaiki infeksi pada pasien sakit kritis.

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Background: The second highest cause of death in the ICU is infectious diseases, which are characterized by negative nitrogen balance. Nutrient intake increases protein synthesis and improves the negative nitrogen balance. This study aims to determine the difference between nitrogen balance and improvement of infections in critically ill patients. Method: This research is a study with a prospective cohort design. Subject retrieval was carried out in the ICU and post-ICU wards at RSCM and RSUI. Characteristics of research subjects include age, gender, nutritional status, diagnosis of main disease, comorbid diseases, use of antibiotics, energy and protein intake. Mean difference analysis was carried out to assess the difference between nitrogen balance and improvement in infection in critically ill patients using the Mann-Whitney test. Results: A total of 42 subjects were critically ill adult patients in the ICU, most of them were men, 27 people (64.3%). The median age of the research subjects was 47 (19-60) years with 14 people (33.3%) underweight (BW). The mean weight and height respectively were 57.29 ± 17.73 and 162.6 ± 7.93. Most research subjects did not have comorbidities with 20 people (47.6%). All research subjects received antibiotic therapy, 42 people (100%). Initial protein intake was 0.39 (0.0-1.1) kcal/kgBW and final protein intake was 0.72±0.34 kcal/kgBW. The first 48 hour nitrogen balance in the ICU was -6.84 (-25.4; 1.6), the average nitrogen balance on day 7 was -5 ± 4.09 with the difference in nitrogen balance being 2.4 (-11.8 ; 27.8). The difference in nitrogen balance between patients who experienced improvement in infection was 3.97 (-11.8; 14.5) (p <0.05), with patients experiencing improvement in infection being 30 people (71.4%). Conclusion: Improvement of nitrogen balance significantly improves infections in critically ill patients."

"Sakit kritis merupakan suatu kondisi terjadinya gangguan fungsi multiorgan yang menyebabkan homeostasis tubuh tidak dapat dipertahankan tanpa adanya intervensi medis di unit perawatan intensif. Proses hiperkatabolik akibat stres metabolik pada pasien sakit kritis terutama di fase akut sangat tinggi sehingga menyebabkan degradasi protein. Tingkat degradasi ini dapat dilihat salah satunya dengan pemeriksaan kehilangan nitrogen melalui urin 24 jam. Asupan energi dan protein berperan penting dalam memelihara proses metabolisme yang terjadi. Asupan yang tidak adekuat diiringi kehilangan protein yang tinggi akan menghasilkan nilai imbang nitrogen yang negatif. Tujuan penelitian ini untuk melihat korelasi asupan protein selama fase akut terhadap perubahan imbang nitrogen yang dinilai pada hari ke-3 dan ke-7 perawatan. Metode penelitian ini menggunakan desain potong lintang yang dilakukan di Intensive Care Unit Rumah Sakit Universitas Indonesia (ICU RSUI) dengan pengambilan sampel secara consecutive sampling. Kriteria penerimaan adalah berusia 18-60 tahun, mendapatkan asupan protein pertama dalam 48 jam, dan bersedia mengikuti penelitian. Kriteria penolakan adalah produksi urin <0.5 ml/kgBB/jam, gangguan fungsi ginjal dan hati kronis, IMT <18.5 atau ≥30 kg/m², skor APACHE II>30, hamil, dan mendapat norepinefrin >0.3 mcg. Kriteria pengeluaran adalah mendapatkan rerata asupan protein hari ke-3 hingga ke-7 <0.5gr/kgBB/hari, dan meninggal sebelum hari ke-7. Pemeriksaan kadar nitrogen urea urin 24 jam dan perhitungan imbang nitrogen dinilai pada hari ke-3 dan ke-7 perawatan. Hasil penelitian menunjukkan rerata asupan protein dan energi pada 21 subyek adalah 0.8 gr/kgBB/hari dan 78% dari EE pada hari ke-3, lalu rerata asupan pada hari ke-7 adalah 1.1 gr/kgBB/hari dan 110% dari EE. Rerata kadar NUU dan imbang nitrogen hari ke-3 adalah 8.1 gr dan -5.3 gr. Rerata kadar NUU dan imbang nitrogen hari ke-7 adalah 7.2 gr dan -1.5 gr. Rerata perubahan imbang nitrogen bernilai positif yaitu 3.8 gr. Terdapat korelasi positif antara asupan energi maupun protein terhadap imbang nitrogen hari ke-3 (r=0.5, p=0.01; r=0.6, p=0.003). Walaupun terdapat perbaikan imbang nitrogen yang signifikan pada subyek penelitian namun tidak didapatkan korelasi bermakna antara asupan protein terhadap perubahan imbang nitrogen (p=0.1). Kesimpulan penelitian ini adalah asupan energi dan protein berkorelasi positif dengan imbang nitrogen pada early acute phase. Asupan protein pada late acute phase tidak berhubungan dengan perubahan imbang nitrogen pada penelitian ini

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Critical illness is a condition where multiorgan dysfunction occurs which causes body homeostasis that cannot be maintained without medical intervention in the intensive care unit. The hypercatabolic process due to metabolic stress in critically ill patients, especially in the acute phase, is very high, causing protein degradation. This level of degradation can be evaluated by examining nitrogen loss through 24-hour urine. Energy and protein intake plays an important role in maintaining the metabolic processes. Inadequate intake accompanied by high protein losses will result in negative nitrogen balance values. The aim of this study was to analyze the correlation of protein intake during the acute phase with nitrogen balance changes on days 3 and 7 of treatment. The method of this study was cross-sectional with consecutive sampling, conducted in the Intensive Care Unit of the University of Indonesia Hospital (ICU RSUI). Inclusion criteria were 18-60 years old, getting their first protein intake within 48 hours, and willing to take part in the research. Exclusion criteria were urine output <0.5 ml/kgBW/hour, chronic kidney and liver function disorders, BMI <18.5 or ≥30 kg/m2, APACHE II score>30, pregnancy, and receiving norepinephrine >0.3 mcg. Drop out criteria were patients having an average protein intake on days 3 to 7 <0.5 gr/kgBW/day, or dying before the 7^th day. Examination of 24-hour urine urea nitrogen (UUN) levels and calculation of nitrogen balance were assessed on days 3 and 7 of treatment. The results of the study showed that the mean of protein and energy intake in the 21 subjects was 0.8 gr/kgBW/day and 78% of EE on day 3, then the mean intake on day 7 was 1.1 gr/kgBW/day and 110% of EE. The mean ​​of UUN levels and nitrogen balance on day 3 were 8.1 gr and -5.3 gr. The mean of UUN levels and nitrogen balance on day 7 were 7.2 gr and -1.5 gr. Mean of nitrogen balance changes was positive, namely 3.8 gr. There was a positive correlation between energy and protein intake with nitrogen balance on day 3 (r=0.5, p=0.01; r=0.6, p=0.003). Although there was a significant improvement in nitrogen balance in the research subjects, there was no significant correlation between protein intake with nitrogen balance changes (p=0.1). The conclusion of this study is that energy and protein intake were positively correlated with nitrogen balance in the early acute phase. Protein intake in the late acute phase was not associated with nitrogen balance changes in this study."

"Latar Belakang: Katabolisme pascalaparotomi menyebabkan imbang nitrogen negatif dan diduga tidak dapat dicegah dengan pemberian nutrisi. Nutrisi parenteral dapat meningkatkan faktor anabolisme. Belum diketahui apakah proporsi asupan energi dan protein dari jalur parenteral terhadap asupan total berkorelasi dengan imbang nitrogen pasien pascalaparotomi elektif.Metode: Studi potong lintang dilakukan di Rumah Sakit Cipto Mangunkusumo (RSCM) pada pasien pascalaparotomi elektif yang memperoleh supplemental parenteral nutrition (SPN) antara 3 hari pertama pascalaparotomi. Pemeriksaan nitrogen urea urin (NUU) dilakukan terhadap pasien dengan asupan ≥ 12 kkal/kg BB pada hari ketiga pascalaparotomi. Pasien dengan gangguan ginjal dan hati tidak disertakan dalam penelitian.Hasil: Rerata imbang nitrogen hari ketiga pascalaparotomi sebesar -2,8 ± 3,8 g/hari, dengan median asupan energi 19 (12–34) g/kg BB dan protein 0,9 (0,4–1,9) g/kg BB. Proporsi asupan energi dari jalur parenteral sebesar 0,51 ± 0,26 dan protein 0,59 ± 0,28. Tidak ditemukan korelasi signifikan pada proporsi asupan energi dan protein dari jalur parenteral terhadap asupan total dengan imbang nitrogen. Korelasi signifikan ditemukan pada variabel total asupan energi (r = 0,697, p <0,001) dan protein (r = 0,808, p <0,001) dengan imbang nitrogen.Kesimpulan: Pemberian SPN dini penting dalam mencapai total asupan energi dan protein untuk mengimbangi kehilangan nitrogen hari ketiga pascalaparotomi elektif di RSCM meskipun korelasi proporsi asupan nutrisi dengan imbang nitrogen belum tampak pada penelitian ini.

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Background: Post-laparotomy catabolism causes a negative nitrogen balance and is unlikely prevented by nutritional intervention. Parenteral nutrition can increase anabolic factor. It is not known whether the proportion of energy and protein intake from parenteral nutrition to total intake correlates with nitrogen balance in elective post-laparotomy patients.

Methods: A cross-sectional study was conducted at Cipto Mangunkusumo Hospital in elective post-laparotomy patients who received supplemental parenteral nutrition (SPN) within first 3 days after laparotomy. Urine urea nitrogen (UUN) examination was performed on patients with intake ≥ 12 kcal/kg BW on the third day after laparotomy. Patients with renal and hepatic impairment were excluded. Results: The mean nitrogen balance on the third day post-laparotomy was -2.8 ± 3.8 g/day, with median energy intake of 19 (12–34) g/kg BW and protein 0.9 (0.4– 1.9) g/kg BW. The proportion of energy intake from the parenteral route was 0.51 ± 0.26 and protein was 0.59 ± 0.28. No significant correlation was found in the proportion of energy and protein intake from the parenteral nutrition to total intake with nitrogen balance. Significant correlations were found for total energy intake (r= 0.697, p <0.001) and protein (r= 0.808, p <0.001) with nitrogen balance. Conclusion: Early administration of SPN is important in achieving total energy and protein intake to compensate nitrogen loss on the third day after elective laparotomy although the association between the proportion of nutrition intake and nitrogen balance has not been observed in this study."

"ABSTRAK Imbang nitrogen pada pasien sakit kritis selalu negatif akibat respon stres. Pada lansia perubahan metabolismenya berisiko memperburuk imbang nitrogen. Tujuan penelitian ini adalah untuk mengetahui imbang nitrogen dan hubungannya dengan asupan energi dan protein pada lansia sakit kritis dalam 48 jam pertama di ICU. Penelitian ini menggunakan metode potong lintang, consecutive sampling. Subyek penelitian adalah 26 lansia sakit kritis. Hasil penelitian pada 24 jam I dan II adalah; imbang nitrogen -5,2 (-31,2 − -4,1) g dan -4,5+4,6; asupan energi 78,8+45,0% dan 91,1+50,2% terhadap target; asupan protein 0,57+0,35 g/kgBB/hari dan 0,71+0,37 g/kgBB/hari serta terdapat korelasi positif bermakna antara imbang nitrogen dengan asupan energi; r=0,6 dan r=0,5 dan korelasi positif bermakna antara imbang nitrogen dengan asupan protein; r=0,5 dan r=0,4. Kesimpulan penelitian ini adalah terdapat hubungan bermakna antara imbang nitrogen dengan asupan energi dan protein pada lansia sakit kritis

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ABSTRAK Nitrogen balance in criticaly ill patients tend to be negative due to stress response. In the elderly patients, the metabolic changes risk to worsening nitrogen balance.The aim of this study is to determine nitrogen balance and its relation with energy and protein intake in critically ill elderly patients within 48 hours in ICU. The study was cross sectional, consecutive sampling on 26 subjects. The nitrogen balances were -5.2 (-31.2 − -4.1) g and -4.5+4.6 g; energy intakes were 78.8+45.0% and 91.1+50.2% target; protein intakes were; 0.57+0.35 g/kgBW/d and 0.71+0.37 g/kgBW/d. There were positive correlation between nitrogen balance and energy intake; r=0.6 and r=0.5, and between nitrogen balance and protein intake; r=0.5 and r=0.4 in 24 hours I and II respectively. The conclusion is there were positive correlation between nitrogen balance with energy and protein intakes."

"Characterizations have been performed on single stage Transversely Excited Nitrogen Laser of Blumlein type. Optical cavity arrangement is varied prior to measurement which shows no significant increase in energy on both configurations of inserting a mirror only and a pair of mirror and a quartz parallel plate. Frequency repetitions respond reveals a small drop in energy at higher frequency i.e. 10 Hz by a factor of 20%. N2 flow rate consideration behaves on the similar way like pressure profile. At higher supply voltage maximum energy is shifted to higher N2 flow rate. A similar tendency occurs on pressure curve but with more pronounced maximum energy. Higher supply voltage would shift maximum energy to higher N2 pressure. Other operating conditions have been kept constant. Beam divergence measurement has given 1,87 mrad on vertical direction and 9,32 mrad on horizontal axis. However, beam cross section experiences a -10° tilt against horizontal reference. This may happen due to a slight twist on main electrodes. Measurements on different date have showed inconsistent results. Major cause is suspected on using different N2 cylinder, replacement on the gauge pressure, and crater creation on HV side spark gap electrode."

"ABSTRACTTwo laboratory-scale sequencing batch reactors (SBR) arranged in series were used to evaluate bioxidadon and nitrogen removal from a synthetic sewage consisting of acetic acid as the carbon source. Microprocessor based timer were used to control various phases in the SBR?s phases. This paper discusses the result of varying recycle ratio, returned mixed liquor, in bioxidation, denitrification and nitrification process in the modified SBR Generally, as the recycle ratio increased if was found to give a better the removal efficiency in terms of organic carbon and total nitrogen removal. The modified SBR, in general. shows promise as an effective treatment alternative to the conventional activated sludge process."

"ABSTRACTThe autofluorescence spectra of human tissues excited with 33'7,1-nm line of pulse nitrogen laser have been measured. The autofluorescence spectra of cancerous tissues consistently exhibit characteristic peaks near E530-nm and 690-nm. which do not appear in the spectra of the corresponding normal tissues. Spectroscopic investigation indicates that the porphyrin compounds localized and retained in cancerous tissues might be responsible for this characteristic autofluorescence. This preliminary result suggests the possibility of employing spectroscopy tool for complementary diagnosis of cancer along with the traditional methods of pathological analysis."

"Pendahuluan: Pasien sakit kritis umumnya mengalami penyusutan otot, pemberian asupan energi yang tidak memadai, dan hipoalbuminemia, yang semuanya dikaitkan dengan luaran yang buruk. Ketebalan otot adduktor pollicis (KOAP) dapat digunakan untuk menilai status gizi. Penilaian status gizi tidak dapat mengabaikan pentingnya menilai proses inflamasi. Rasio neutrofil terhadap limfosit (neutrophil-to-lymphocyte ratio atau NLR) baru-baru ini diperkenalkan sebagai pananda inflamasi. Penelitian ini menganalisis hubungan KOAP, asupan energi, albumin serum, dan NLR dengan mortalitas 28 hari.Metode: Studi kohort prospektif dilakukan di unit perawatan intensif (intensive care unit atau ICU) Rumah Sakit Cipto Mangunkusumo, dari Februari hingga Maret 2020. KOAP diukur dengan alat caliper. Asupan energi dihitung berdasarkan jumlah kalori yang diterima pasien. Hitung jenis sel darah putih dan albumin serum diperiksa saat masuk ICU. Luaran utama adalah mortalitas 28 hari.Hasil: Penelitian ini melibatkan 49 pasien dengan angka kematian 20,4%. Rerata asupan energi hari pertama adalah 552,2 ± 235,6 kkal atau 47,0% dari target. Nilai median NLR pada semua subjek adalah 13,28 (minimal 3,50 - maksimal 59,56). Ada hubungan yang bermakna antara kelompok subjek dengan NLR tinggi (≥13,28) dan kelompok NLR rendah (<13,28) terhadap mortalitas (p = 0,031), tetapi tidak ada perbedaan yang bermakna secara statistik antara APMT (24,25 ± 4,65 vs. 24,97 ± 3,59 mm, p = 0,596), asupan energi (kategori asupan energi kurang sebagai pembanding), dan rerata albumin serum (2,67 ± 0,54 vs. 2,64 ± 0,80 g/dl, p = 0,928). Analisis multivariat untuk menilai kemampuan gabungan variabel independen diperoleh nilai area under curve (AUC) sebesar 78,7%.Kesimpulan: Kombinasi KOAP, asupan energi, albumin serum, dan NLR mempunyai kemampuan yang cukup memuaskan dalam memprediksi mortalitas pada pasien sakit kritis.

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Introduction: Critically ill patients usually experience muscle wasting, inadequate energy intake and hypoalbuminemia, all of which were associated with poor outcomes. Adductor pollicis muscle thickness (APMT) can be used to assess nutritional status. Assessment of nutritional status cannot ignore the importance of inflammatory process. Neutrophil-to-lymphocyte ratio (NLR) was recently introduced as an inflammatory biomarker. This study analyze the relationship between APMT, energy intake, serum albumin, and NLR with 28-day mortality.

Methods: A prospective study was conducted in intensive care unit (ICU)’s of a tertiary care hospital, Indonesia, from February to March 2020. APMT was measured at admission with a caliper. Energy intake was calculated based on the number of calories received by the patient. Albumin serum and leukocyte differential count were checked at ICU admission. The primary outcome was 28-day mortality.

Results: This study involved 49 patients with mortality rate of 20.4%. Mean energy intake at first day was 552.2±235.6 kcal or 47.0% of the target. Median value of NLR of all subjects was 13.28 (minimum 3.50 – maximum 59.56). There was statistically significant relationship between non-survivor and survivor group with high NLR (≥13.28) and low NLR group (<13.28) for mortality (p=0.031), but there was no statistically significant difference between APMT (24.25±4.65 vs. 24.97±3.59 mm, p=0.596), energy intake (less energy intake category as a comparison), and mean serum albumin (2.67±0.54 vs. 2.64±0.80 g/dl, p=0.928). Multivariate analysis to assess combined ability of independent variables to predict mortality obtained a satisfactory area under curve (AUC) value of 78.7%.

Conclusion: The combination of APMT, energy intake, serum albumin, and NLR has a satisfactory ability in predicting mortality in critically ill patients."

"Tingginya permintaan pengujian kualitas air permukaan di laboratorium komersil menyebabkan adanya antrian. Dengan adanya antrian, maka sampel yang diserahkan memiliki kemungkinan tidak langsung diuji sehingga sampel akan mengalami fase yang dinamakan fase waktu tunggu. Penelitian ini bertujuan untuk menganalisis perubahan nilai konsentrasi nitrogen selama rentang waktu tunggu. Selain itu, penelitian ini bertujuan menentukan laju perubahan selama proses nitrifikasi berdasarkan nilai perubahan konsentrasi yang terjadi. Kemudian penelitian ini bertujuan untuk memperkirakan nilai konsentrasi awal dari setiap parameter yang ada di dalam proses nitrifikasi. Adapun metode yang digunakan untuk mengetahui perubahan nilai konsentrasi nitrogen selama waktu tunggu adalah dengan melakukan pengujian laboratorium berdasarkan HACH. Sedangkan penentuan laju perubahan yang terjadi dilakukan dengan menggunakan metode Solver. Analisis perkiraan nilai konsentrasi awal dilakukan dengan pemodelan yang menggunakan solusi persamaan ODE Linear faktor pengintegrasian. Hasil pengujian laboratorium menunjukan adanya perubahan nilai konsentrasi amonia, nitrit, dan nitrat dari sampel yang didiamkan selama rentang waktu 14 hari dengan kondisi tanpa diawetkan dan dengan diawetkan. Rentang persentase perubahan nilai konsentrasi yang terjadi adalah sebesar 0,4% - 100% untuk amonia, 7% - 300% untuk nitrit, dan 18,2% - 960% untuk nitrat. Nilai laju perubahan amonia secara berurutan adalah 0,74/hari dan 0,4/hari untuk sampel tanpa pengawetan dan dengan pengawetan sedangkan nitrit adalah sebesar 0,05/hari dan 0,08/hari. Nilai error terkecil ada pada hari kedua untuk meperkirakan konsentrasi awal. Nilai konsentrasi amonia, nitrit, dan nitrat dengan kondisi tanpa pengawetan dan dengan pengawetan secara berurutan dengan menggunakan hari kedua sebagai waktu acuan adalah 17,29 dan 13,17 mg/L, 2,84 dan 15,26 mg/L, 0,93 dan 1,46 mg/L

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The high demand for surface water quality testing in commercial laboratories causes queues. With the existence of a queue, the samples submitted have the possibility of not being directly tested so that the sample will experience a phase called the holding time phase. This study aims to analyze changes in the value of nitrogen concentrations during the waiting period. In addition, this study tries to determine the level of change during the nitrification process based on the value of the changes in concentration that occur. Then this study aims to develop the concentration of the initial value of each parameter in the nitrification process. The method used to determine changes in the value of nitrogen concentration during the holding time is by conducting laboratory tests based on HACH. While the rate of change that occurs is done using the Solver method. Analysis of the estimated value of the initial concentration was carried out by modeling using the solution of the Linear integrating factor ODE equation. The results of laboratory tests showed that there was a change in the concentration values of ammonia, nitrite, and nitrate from the samples which were left for a period of 14 days with unpreserved and preserved conditions. The proportion of change in concentration value that occured is 0,4% - 100% for ammonia, 7% - 300% for nitrite, and 18,2% - 960% for nitrate. The value of the rate of change of ammonia respectively is 0,74/day and 0,4/day for samples without preservation and with preservation while for nitrite is 0,05/day and 0.08/day. Most of the smallest error value exist on the second day to estimate the initial concentration. The concentration values of ammonia, nitrite and nitrate under the condition of unpreserved and preserved respectively using the second day as a time reference were 17,29 and 13,17 mg/L, 2,84 and 15,26 mg/L, 0,93 and 1,46 mg/L."