w y wz 9«( 3y) 199~206, 2006 J. of the Korean Society for Environmental Analysis sƒ(i) ½» *Áx Á * w yw w, w y œw Evaluation of Manual and Automated Methods in Total Nitrogen (TN) and Total Phosphorus (TP) Analysis (I) TN Analysis Kee Dong Kim*, Mi-Kyung Heo, and Yong-Chan Seo *Department of Fine Chemical and Advanced Materials, Sangji University, 660 Usan-dong, Wonju, Korea Department of Environmental Engineering, Sangji University, 660 Usan-dong, Wonju, Korea Automated instrumental analyses are introduced for the determination of total nitrogen (TN) and total phosphorus (TP) in water. Since the automatized analysis provide very reliable data with less labor and chemicals, it is considered as a replaceable technic for substituting the currently available manual method. Actually, this automated technic has been practically used for the determination TN and TP in compliance with water quality monitoring regulation in Korea. Automated method is also adapting the same operating principle of manual analysis which is approved by Ministry of Environment of Korea. Segmented flow analysis (SFA) system was applied for automated technic for the simultaneous determination of TN and TP. TN concentration data obtained by both manual and automated techniques are evaluated for the mutual comparability. Method detection level (MDL), precision, accuracy, interferences, etc. values were compared, either directly or after statistical treatment, to test equivalency between two methods. Automated method turned out to be at least equivalent or better than manual method in TN determination of relatively clean water sample. One of the main restrictions in broadening the application of automated method is found to be its narrow range of detection in analyzing water sample espcially ones containing high concentrated suspended solid. Particulate matters in water samples interfere the determination of TN concentration negatively, in general. Key words : total nitrogen (TN), total phosphorus (TP), segmented flow analysis (SFA), automated analysis 1. œ» ƒ w yw l w»¾, ƒ w l w ¾ w š ¾ ƒ š ywš.»» w.» (Albuminoid), (C 5 H 4 N 4 O 3 ).»,, ƒ. š k» w w. t» w. t w w ùkù» w. w 10 mg NO 3 -N/L wwš. w» yw To whom correspondence should be addressed. E-mail : ycseo@sangji.ac.kr
200 ½» Áx Á w wù w w. y w». ³ w yw yw y y., w y w y w» w w tƒ. t s w. w û ùkü, m m». 1~3) œ x w d w» w»» ww z, w. ww w š, ƒƒ w. ù œ x w k. ù,,» w wš. ù ¾. y w š k». œ w, l w w œ w e ü w. 4) y (Flow Injection analysis, FIA) 5,6) (Segmented Flow Analysis, SFA) 6-8) ƒ ù. x x ƒ r SFA w w. SFA w k (validation) sƒ w» w (method detection, level, MDL), x, spike recovery m w y, w, w matrix w ƒ xw. 2. 2.1. 2,9,10)» w w, s, s, w, s, 2 L w 4C þ o w. y x w» w s, w Whatman GF/C 4 mm Ø w z 3 z x w, t 2 mg/l, t 5 mg/l w y xw (Table 1).»»ƒ ù w y w» w, Amonium Chloride (NH 4 Cl), EDTA (C 10 H 14 N 2 Na 2 O 8 2H 2 O), L-Glutamic acid (HOOC (CH 2 ) 2 CH(NH 2 )COOH) ƒ yw 2 mg N/L 5 mg N/L w. w» w ƒ (Fe) (Cu) yw w. œ x w w. t (1, 5 mg NO 3 -N/L) (250, 500, 1000, 2500, 5000, 10000, 25000 mg/l) ƒw w y w. 2.2.»»» 2.2.1. ( ŸŸ ) Ÿ Varian Carry 50 UV Spectrophotometer 220 nm d w. Autoclave 120 C o Table 1. Sample specifications for the analysis of TN and TP No Sample Samplind date Sampling Station 1 Stream Water 2006.04 Nak Dong river, Won Ju Jusan bridge 2 Textile Wastewater (Effluent) 2006.03 Su Won Banwol Plants 3 Saline Wastewater (Effluent) 2006.04 Won Ju Kim-chi Plant 4 POTW * Effluent 2006.04 Won Ju Municipal Effluent 5 Livestock Wastewater 2005.11 Won Ju Hyantogyebal 6 POTW (Inffluent, Effluent) 2005.11 Nak Dong river * Publicly owned treatment works
sƒ(i) 201 30 ƒ w w w 100 ml ü ü w. 2.2.2.»» (ep y ) 11) BRAN-RUEBBE AACS w»» Table 2 w. y»» w (TN) Diagram, ƒ w. Table 2. Analitical condition of automatic analysis system Instrument Part Digester temperature TN Heating block temperature Air Compressor Pressure : Main Gage (for digester) Homogenizer time Micro Wave (TN) 2.3. p w. 2.3.1. ( ŸŸ ) Condition 110 o C TN(40 o C) 0.29 Mpa 0.13 Mpa 20 sec 550 nm Fig. 1. A schematic diagram for the analysis of total nitrogen (TN). (TN) a) e y e : 500 ml yùp (NaOH;, x w 0.0005% w ) 15 g y e (Potassium Persulfate, K 2 S 2 O 8 ;, x w 0.0005% w ) 15 g. w w. b) (1+16) : 160 ml w (c-hcl) 10 ml yww. 2.3.2.»» (e y ) (TNTP) a) e y e (Alkaline peroxodisulfate) : y e (Potassium Persulfate, K 2 S 2 O 8 ;, x w 0.0005% w ) 12.5 g, (Boric acid) 5.0 g, yùp (NaCl) 0.5 g, y ùp (Na 2 SO 4 ) 0.5 g 500 ml z 2.0 ml 5 N- NaOH š 500 ml ƒ. v ph 8 b) y : 100 ml z y 16 ml š 200 ml. (TN) a) (imidazole) : 30 g 800 ml z y (H 2 SO 4 ) 4 ml ƒw. 1000 ml¾ z 1 ml 50% triton-x š. b) NED color : NED (N-1-Nap-hthylethylenediamine 2HCl) 0.5 g, (HCl) 5 ml z 500 ml. c) Sulfanilamaide : r (Sulfanilamaide) 5 g, (HCl) 50 ml 500 ml w. 2.3.3. (TN) t 2.3.3.1. ( ŸŸ ) t (100 mg NO 3 -N/L) : 105-110 C 4 w e o (KNO 3 ; t ) 0.7218 g y 1000 ml w. t (100 mg NO 3 -N/L) 10 w w z (1+500) 2 ml š w.
202 ½» Áx Á 2.3.3.2.»» (Segmented Flow Analysis, SFA) t (1000 mg NO 3 -N /L) : 105-110 C 4 w e o (KNO 3 ; t ) 0.7218 g y 100 ml w. t (1000 mg NO 3 -N/ L) 20 ml 100 ml w t 200 mg NO 3 -N/L w. yw t 1.25, 2.5, 5 ml w 100 ml w š w. 3. š 3.1. 12,13) 3.1.1. š t ƒƒ 0~10 mg NO 3 -N/L w w. Table 3 ( ŸŸ ) r 2 = 0.9995 š,»» r 2 = 0.9970. ù ŸŸ w»» 6 mg NO 3 -N/L Ÿ ƒ 1. Lambert-beer e w Ÿ 1 w, 5 mg NO 3 -N/L w š w. 3.1.2. w (MDL) t 0.2 mg NO 3 -N/L w 7 œ x»» (SFA) w. š ƒƒ t r 3.14( 95% t ) w w (MDL) w. œ x w 0.12 mg/l š,»» (SFA) w 0.02 mg/l û w (MDL). 3.1.3. x ü w kw w. Û10%. ( ŸŸ )»» Table 4 Û10%. œ x»» û t r (RPD, %) ùkü x. RPDƒ 10% w w ƒ ù Table 3. Precision data š q. Manual Automated Linearity r 2 = 0.9995 r 2 = 0.9970 M.D.L. 0.12 mg/l 0.02 mg/l Duplicate 0.8-28.1% (Ave. 9.08%) 0-13.7% (Ave. 2.12%) Table 4. Results of replicate analysis of TN data Sample Stream Water Livestock Wastewater Wastewater Treatment Area Saline Wastewater Sample ID A B C D E F G H I Method Sample Concentration (mg/l) Duplicate Concentration (mg/l) % RPD Automated 3.808 3.714 2.5 Manual 3.788 3.637 4.1 Automated 1.679 1.925 13.7 Manual 1.777 1.534 14.7 Automated 11.060 11.400 3.0 Manual 13.571 10.209 28.1 Automated 4.129 3.972 3.9 Manual 4.193 4.272 1.9 Automated 2.930 3.015 2.9 Manual 3.475 3.805 9.1 Automated 3552.5 3692.5 3.9 Manual 2630.8 2609.37 0.8 Automated 52.150 52.150 0 Manual 54.352 56.572 4.0 Automated 29.540 28.260 4.4 Manual 33.038 27.338 18.9 Automated 10.300 10.400 1.0 Manual 12.259 12.038 1.8 3.1.4. z (Recovery) z (Recovery, %)» w» t ƒw w 80-120% ü. 3.1.5 w w t w ƒƒ (0.5, 1, 2, 5, 100, 300, 500 mg/l) (0.5, 1, 2, 5, 10, 50, 100, 300, 500 mg/l) y, ƒw z., t 2 mg NO 3 -N/L w wƒ ù ƒ û wƒ.
sƒ(i) 203 Table 5. Interference of total nitrogen analysis induced by copper and iron (spiked concentration, 2 mg N/L) Interfer ence Copper (Cu) Iron (Fe) Concentration (mg/l) Automated Mesured (mg/l) % Mesured Recovery (mg/l) Manual % Recovery 0.5 2.171 108.525 1.999 99.968 1 2.099 104.95 2.234 111.680 2 2.077 103.85 2.253 112.647 5 2.103 105.125 2.047 102.350 100 2.045 102.25 2.318 115.924 300 1.953 97.65 2.055 102.762 500 1.680 84 1.874 93.700 0.5 2.189 109.45 2.073 103.625 1 2.153 107.65 2.725 136.25 2 2.046 102.3 2.367 118.342 5 2.110 105.5 2.471 123.535 10 2.052 102.6 2.340 116.981 50 2.097 104.85 2.211 110.534 100 2.243 112.15 2.592 129.588 300 2.202 110.1 2.470 123.446 500 2.335 116.75 2.693 134.638 w w t 1 mg NO 3 -N/L 5 mg NO 3 -N/L ƒƒ 7 w (250, 500, 1000, 2500, 5000, 10000, 25000 mg/l)w d w. positive error ùkü ƒ, ƒ û j w y w.»» w œ x w ƒ w. 3.2.»» (SFA) p 14) Table 8»»» w Table 6. Interference of total nitrogen analysis induced by chloride (spiked concentration, 1 mg N/L) Unit : mg/l Cl - Manual RPD (%) Automated RPD (%) 250 1.268 23.648 1.090 8.612 500 1.152 14.159 0.996 0.401 1000 1.340 29.043 1.095 9.069 2500 1.212 19.194 1.023 2.274 5000 1.496 39.727 0.988 1.207 10000 1.233 20.844 0.932 7.093 25000 1.428 35.231 1.042 4.114 Table 7. Interference of chloride an total nitrogen analysis (spiked concentration, 5 mg N/L) Unit : mg/l Cl - Manual RPD (%) Automated RPD (%) 250 5.433 8.306 4.969 0.622 500 5.392 7.543 5.015 0.300 1000 5.471 8.987 5.226 4.420 2500 5.491 9.358 5.042 0.836 5000 5.352 6.797 4.920 1.613 10000 5.423 8.113 4.977 0.461 25000 5.581 10.984 4.804 3.998 t 5 mg/l 10z w t r wš 95.5% t 2σ w š, 99.7% t 3σ w w w. 13 t d w»» y w. ƒ ( w ƒ û ) (CV%)ƒ 3% w w.»» y» w w. t 5 mg/l w 10z d w,»» 99.9% w w. Table 8. Reproducibility of verification sample analysis Frequency TN (5 mg N/L) 1 5.2580 2 5.1340 3 4.9830 4 5.1350 5 5.2810 6 5.0660 7 5.2320 8 5.2040 9 4.9890 10 5.0430 Average 5.1325 SD 0.1096 CV(%) 2.1362»» y q w» w Amonium Chloride (NH 4 Cl), EDTA (C 10 H 14 N 2 Na 2 O 8 2H 2 O), L-Glutamic acid (HOOC(CH 2 ) 2 CH(NH 2 )COOH) œ ƒw ƒƒ 2 mg N/L 5 mg N/Lƒ w w. Table 9
204 ½» Áx Á 97-103% z ùkü»» w š. Table 9. Recovery of total nitrogen Mean Recovery % Compound 2 mg N/L 5 mg N/L Amonium Chloride 97.45 100.43 EDTA 106.93 102.08 L-Glutamic acid 100.28 101.52 3.3. ƒƒ w, š s w ( ŸŸ )»» d w w. x ƒ š w» w t x ww. 95% w w t Student t w y w. Fig. 2. Comparison between Manual and Automated Analyses of Stream Water (TN) r 2 = 0.9993 y w. s³ w ùküš. t = d ---- n s d d d i ( )2 s d = --------------------------- n 1 w 63 w l t 3.814 š 95% Student t 1.999 w ùkû. ù s³ w ùküš, w w q. w w 9 w 54 w t 1.848 š 95% Student t 2.002 y w, w t(fig. 2) r 2 = 0.9923 y w. (, ) 7 w t 2.017 š 95% Student t 2.447 w y. w t (Fig. 3) Fig. 3. Comparison between Manual and Automated Analyses of Wastewater Treatment Area (TN). s 5 w t 1.243 š 95% Student t 2.776 w y. w t (Fig. 4) r 2 = 0.9389 y ù Áòw w. s³ w ùküš. ù
sƒ(i) 205 ƒ k m yw w. Fig. 4. Comparison between Manual and Automated Analyses of Livestock Wastewater (TN). 4. 4.1. t ƒƒ 0-10 mg NO 3 -N/L yw w r 2 = 0.9995 š,»» r 2 = 0.9970 š. w (MDL) œ x w 0.12 mg/l š,»» (SFA) w 0.02 mg/l û w., x Û10 % w ù œ x»» û t r (RPD, %) ùkü»» x q. RPD (%)ƒ 10% w w ƒ ù š q. w z (Recovery, %) ƒ 80-120% ü. w w w w wƒ ù ƒ û wƒ. w ùkû,»» w œ x w ƒ w. 4.2.»» (SFA) z x 4.2.1. z t 5 mg/l 10z w»» (CV%) 3% w w š 99.9% š. ù ƒ w. Amonium Chloride (NH 4 Cl), EDTA (C 10 H 14 N 2 Na 2 O 8 2H 2 O), L-Glutamic acid (HOOC(CH 2 ) 2 CH(NH 2 ) COOH) ƒƒ 2 mg N/L 5 mg N/L w»» œ w z x 97-103%»» d š. 4.2.2. ƒƒ w, š s w ( ŸŸ )»» d w w w (, ) x w w w eƒ ù s ƒ ùkùš. ù s ƒ e w». xk y ù,»» p w yw ùkü. wš t x w 95% w w š. w š, w ƒ š w. w wš» d w ù, p x w ƒ»w w q w.
206 ½» Áx Á š x 1. ½ k, œ x w, Ÿ q, 1997. 2. Standard Method, Nitrogen, 4500-N A. 3. ½, y, y, y yw,», 2000, p 625-641. 4. Gray D. Christian,, w,, q», w œ, yw,, 1996, p 599-600. 5. ½k,, Flow Injection Analysis (FIA), w w» yw, Vol. 1, No 2, 1988. 6. Ÿv, {, Ÿ, Flow Injection Analysis, w t w», Vol. No 2, 1995. 7. Standard Method, Segmented Continuous Flow Analysis, 4120 A. 8. Standard Method, Inorganic Nonmetals by Flow Injection Analysis, 4130 A. 9. Standard Method, Quality Assurance/Quality Control, 4130 A, 4130 B. 10. Standard Method, Nitrogen, 4500-N B. 11. U. S. EPA, Nitrogen, Nitrate-Nitrite (Colorimetric, Automated, Cadmium Reduction), Method 353.2. 12., Auto Analyzer w w (2), e w. 2001. 13. j e g, eƒ f e, yw x d Auto Analyzer y (œ x w z ), ( ) i p l», 2001. 14. Daniel C. Harris, ½, ½w,,, yw 5th. ed. e, p 89-99.