Low-concentration Nutrient Determination Needs and Challenges—Which Ones? Needs and Challenges Which Ones? How Low? What Applications? Charles J. Patton 1 and William Lipps 2 1 U.S. Geological Survey National Water Quality Laboratory P.O. Box 25585, Denver, Colorado 80225-0585 2 ITT | OI Analytical ITT | OI Analytical College Station, TX 77842-9010 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges in Low-concentration Nutrient Analyses
Speakers for Challenges of low concentration nutrient analysis Speakers for Challenges of low-concentration nutrient analysis morning and afternoon sessions 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
Analytical service laboratory Prod ction sample processing Production sample processing ~ 30,000 samples/year, 30 000 samples/ ear ~ 1.5 x 10 6 determinations Quality Assurance/Quality Control New methods development including laboratory automation 2011 NEMC, Bellevue, WA Challenges of Low-concentration Nutrient Analyses
Overview of Overview of Yearly of Yearly of Nutrient Nutrient Concentrations in Concentrations in Surface Water and Surface Water and Groundwater Groundwater in the United States Groundwater Groundwater in the United States in the United States in the United States Nitrogen- and Phosphorus-containing Nitrogen- and Phosphorus-containing Nutrients – Filtered, Undigested – Filtered, Digested – Whole-water, Digested Detection limits Detection limits Laboratory blanks Blind blanks Field blanks Field blanks 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
Differences in concentration distributions for different water Differences in concentration distributions for different water types 100 Surface water n = 7 000 Surface water, n = 7,000 21.6 Groundwater, n = 2,884 (mg-N/L) 9.9 7.7 10 3.4 3.2 centration ( 1 4 1.4 0.9 1 0.5 0.17 itrate Conc 0 1 0.1 0.03 0.02 0.01 0.01 N 0.001 10th 25th Median 75th 90th 99th Percentile Percentile Percentile Percentile percentile 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Di NWQL Di NWQL Disso NWQL Di ssolve l ved N d N d Nutrien N t i ent A t A t Ana A nalyses l yses i i i 2010 in 2010 2010 2010 15,000 All results 13,296 13,050 QL in 2010 12,705 In-range 12,500 < MDL 0.004 - 0.20 11,029 mg-P/L Off-scale at the NWQ 10,000 0.001 - 0.20 0.02 - 5.00 mg-N/L 0.01 - 0.80 mg-N/L mg-N/L 7,500 s Analyzed a 6231 (48%) 4751 5,000 4,081 (37%) 0.008 - 1.00 Samples mg-N/L 2291 1996 2,500 (21%) (15%) 1368 (34%) 0 Ammonium Nitrate Low-level Nitrate Nitrite Orthophosphate 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Dissolved and Total Nitrogen Analyses in 2010 6,692 All results All results 7,000 7 000 0.05 - 5.0 0 05 5 0 0 WQL in 2010 In-range mg-P/L < MDL 6,000 Off-scale d at the NW 5,000 4,704 0.05 - 5.00 mg-N/L 4,053 4,000 0.05 - 5.0 3,397 0.05 - 5.0 mg-N/L mg N/L mg-N/L les Analyze 3,000 2,000 706 706 476 476 323 323 307 307 Samp (17%) (14%) (5%) (7%) 1,000 0 Alk li Alkaline Persulfate P lf t Alkaline Persulfate Alk li P lf t Di Dissolved Kjeldahl l d Kj ld hl T t l Kj ld hl Total Kjeldahl Digestion DN Digestion TN Nitrogen (DKN) Nitrogen (TKN) 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Dissolved and Total Phosphorus Analyses in 2010 9,000 8,452 All results All results 0 WQL in 2010 In-range 7,500 < MDL 0.004 - 0.20 Off-scale mg-P/L d at the NW 6,000 0.02 - 2.00 4,316 4,500 mg-P/L es Analyzed 0 003 0.003 - 0.20 0 20 0.01 - 2.00 mg-P/L mg-P/L 3,000 2,482 2,146 163 1,097 1137 368 Sample (7%) (7%) 1,554 1 554 (25%) (25%) (13%) (13%) (17%) (17%) 220 254 1,500 (14%) (47%) 536 0 Alk. Persulfate Alk. Persulfate Acid Persulfate Acid Persulfate Kjeldahl Kjeldahl Digestion DP Digestion TP Digestion DP Digestion TP Digestion DP Digestion TP 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Ammonium Analyses 2010(Discrete Analyzer) NWQL A i A l 2010(Di t A l ) 0.04 + N L) + -N method (mg-N/L DA S li DA Salicylate/Hypochlorite NH 4 l t /H hl it NH th d 0.03 0.02 n = 75 ntration n = 567 95% 95% n = 52 n = 77 0.01 95% m Concen 5% 5% 95% 95% 0.00 5% 5% monium 5% -0.01 -0.02 Am MDL Calibrant Lab Blank Blind Blank Field Blank 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Nitrite Analyses 2010 (Discrete Analyzer) 0.0035 L) (mg-N/L - -N method DA NO 2 0.0030 n = 74 95% 0.0025 tration ( 0.0020 0.0015 n = 545 5% Concent n = 74 n = 52 0.0010 95% 95% 95% 0.0005 Nitrite C 0.0000 5% -0.0005 5% 5% N -0.0010 MDL Calibrant Lab Blank Blind Blank Field Blank 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
Relationship between nitrate nitrite and nitrite Relationship between nitrate + nitrite and nitrite concentrations analyzed at the NWQL in 2010 2.25 WG: Nitrite ≥ 0.05 mg-N/L. n = 45 2.00 WS: Nitrite ≥ 0.05 mg-N/L. n = 425 LC 3156 dilution limit -N/L) 1.75 LC 3157 dilution limit ntration (mg- 1.50 1.25 1.00 Nitrite Conce 0.75 0.50 0.50 N 0.25 0.00 0 1 0.1 1 1 10 10 100 100 Nitrate + Nitrite Concentration (mg-N/L) 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Standard-level Nitrate Analyses 2010 (Continuous- NWQL Standard level Nitrate Analyses 2010 (Continuous flow Analyzer) - N L) Standard-level CdR NO 3 -N method St d d l l CdR NO th d n (mg-N/L 0.08 0.06 0.06 n = 221 221 centration 95% 0.04 5% rite Conc n = 433 n = 221 n = 221 0.02 95% 95% 95% rate + Nit 5% 5% 0.00 5% Nitr -0.02 MDL Calibrant Lab Blank Blind Blank Field Blank 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
NWQL Low-level Nitrate Analyses 2010 Analyses 2010 NWQL Low level Nitrate Analyses 2010 Analyses 2010 (Continuous-flow Analyzer) 0.025 - -N method (mg-N/L) ) Low-level CdR NO 3 n = 61 0.020 95% centration 0.015 5% n = 204 95% 0 010 0.010 trite Conc n = 52 n = 119 95% 95% 0.005 rate + Nit 0.000 5% 5% 5% -0.005 Nit MDL Calibrant Lab Blank Blind Blank Field Blank 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
Cadmium reactors are easily incorporated Cadmium reactors are easily incorporated into continuous flow analyzers CFA Cadmium Reactors Debubbler Air Air - NO 2 Complexing Buffer - ) Sample (NO 3 - NO 2 Complexing Buffer FIA - ) Sample (NO 3 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
Discrete analyzer nitrate reductase (AtNaR2) nitrate assay ( 37 ° C)—now USGS approved NaR NO NADH H NO NAD H O 3 ( 7;30 C) 2 2 pH 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
CFA cadmium CFA cadmium CFA cadmium-reduction and DA CFA cadmium reduction and DA reduction and DA enzyme reduction and DA enzyme enzyme reduction nitrate enzyme-reduction nitrate reduction nitrate reduction nitrate concentration data concentration data pairs plotted about pairs plotted about the the line of line of equal relation equal relation 100 Surface water (Medium Code = WS) 25 mg-N/L n (mg-N/L) Groundwater (Medium Code = WG) Artificial matrix sample (Medium Code = OA) 5.0 mg-N/L Interstitial water sample (Medium Code = WI) 10 Surface-water QA sample (Medium Code = WSQ) Concentration Groundwater QA Sample (Medium Code = WGQ) Line of equal relation for CFA-CdR and DA-AtNaR2 methods Interim Reporting Limit (IRL) Set point for automatic 1+4 dilution 1 Set point for prompt to enter a larger dilution factor Set point for prompt to enter a larger dilution factor R2 Nitrate C Regression Parameters 0.04 mg-N/L 0 1 0.1 y = 1.0004x - 0.0092 y 1.0004x 0.0092 DA AtNa r 2 = 0.9998 n = 101 Kone run # 0134B on May 14, 2008 0 01 0.01 0.01 0.1 1 10 100 CFA CdR Nitrate Concentration (mg-N/L) 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
CFA CFA ca CFA CFA cadmium-re d d i um-reduc d d ucti t ti tion i on an and DA d DA d DA enzyme-re d enzyme-reduc d d ucti tion t ti i on l l low- l ow-leve l l evel l i l l nit it itra rate t concentration data pairs plotted about the concentration data pairs plotted about the line line of of equal relation equal relation 1 Nitrate DA-AtNaR2 N ) tion (mg-N/L 0.1 Linear regression, all data y = 1.030 x + 0.002 w-level (LL) D Concentrat Surface water Groundwater 0.01 Blind blanks Low Line of equal relation NWQL LL CFA-CdR MDL and LL DA-AtNaR2 IRL 0.001 0 001 0.001 0 01 0.01 0 1 0.1 1 1 Low-level (LL) CFA-CdR Nitrate Concentration (mg-N/L) 2011 NEMC, Bellevue, WA Tuesday, August 16 Challenges of Low-concentration Nutrient Analyses
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