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LIMITED (CLASSICAL) CHEMISTRY METHODS Presented by Stu Nagourney NJDEP, OQA.

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Presentation on theme: "LIMITED (CLASSICAL) CHEMISTRY METHODS Presented by Stu Nagourney NJDEP, OQA."— Presentation transcript:

1 LIMITED (CLASSICAL) CHEMISTRY METHODS Presented by Stu Nagourney NJDEP, OQA.

2 WHAT WELL COVER TODAY 4 Analytical Test Methods –Physical Properties –Inorganic Non-Metallic Constituents Halogens & Cyanide Nutrients –Aggregated Organics 4 Method-specific QA/QC issues 4 Method Applications & Limitations

3 WHAT WE WONT COVER TODAY 4 Method requirements for individual programs 4 Generic QA/QC principles 4 Oil & Grease 4 Total Petroleum Hydrocarbons 4 NJQLs

4 SAMPLE COLLECTION & PRESERVATION ParameterPreservationContainerHold Time AlkalinityCool 4 ºCP or G14 days NH 3 -NCool 4 ºC;P or G28 days H 2 SO 4 to pH<2 Cl -, Br -, F - None P28 days CN - NaOH to pH>12;P or G14 days Cool 4 ºC ; Ascorbic acid HardnessH + to pH<2P or G180 days Kjeldahl orH 2 SO 4 to pH<2P or G28 days Organo-N (NO 3 ) - H 2 SO 4 P or G14 days To pH<2 (NO 2 ) - Cool 4 ºCP or G2 days o-(PO 4 ) -3 Filter ASAP;P or G2 days Cool 4 ºC Sp. Cond.Cool 4 ºCP or G28 days (SO 4 ) -2 Cool 4 ºCP or G28 days TDS, TSSCool 4 ºCP or G7 days TurbidityCool 4 ºCP or G2 days

5 PHYSICAL METHODS

6 TURBIDITY 4 References –USEPA –SM 2130B 4 Applies to DW & WP 4 Caused by fine suspended matter; its a measure of the clarity of water 4 Units are NTUs; –<1 required for DW analyses of metals

7 TURBIDITY - NEPHELOMETROMETRY 4 Compares intensity of scattered light 4 Instrument sensitivity must be able to detect turbidity differences of 0.02 NTU 4 Lab. reagent water may have to be filtered prior to use 4 Anything blocking light path NG: scratches, smudges, air bubbles,...

8 ALKALINITY 4 References –USEPA –SM 2320B 4 Applies to DW & WP 4 Measures acid-neutralizing capacity (ANC) 4 Mostly measures (CO 3 ) -2, (HCO 3 ) - & OH -

9 ALKALINITY 4 Oily matter, ppcts. may interfere but cannot be removed since they contribute to ANC 4 Analysis by HCl (or H 2 SO 4 ) titration (end-pt. or potentiometric (most accurate) 4 For low alkalinity samples (<20), equivalence pt. determined by extrapolation 4 RSDs < 5% can be commonly achieved

10 HARDNESS 4 References –USEPA –SM 2340B: Sum separate calculations of Ca & Mg –SM 2340C: EDTA Titration 4 Defined as the sum of [Ca] & [Mg], expressed as CaCO 3 4 Applies to DW & WP

11 HARDNESS 4 Ca +2 / Mg +2 sequestered by NaEDTA 4 Titration to dark bluer; forms starch-I complex 4 Transition metals can interfere –Inhibitors are added to complex metals prior to analysis 4 LOD ~ 0.5 mg/L as CaCO 3 ; RSDs of <3% common

12 CONDUCTIVITY 4 References –USEPA –SM 2510B 4 Applies to DW & WP 4 Measures the ability to an aqueous solution to carry an electrical current 4 CO 2 in air can cause low levels

13 CONDUCTIVITY

14 4 Units of measure: S/cm ( mhos) 4 Use KCl solutions as stds; 25 ºC 4 Distilled water mhos; most potable waters range from mhos 4 Cell Constant –Determine annually –Verify w/each use w/known [KCl] 4 RSDs < 1%

15 SOLIDS 4 Total Solids (TS): residue left after heating a defined T 4 Total Suspended Solids (TSS): portion of solids retained by a filter 4 Total Dissolved Solids (TDS): portion of solids that passes through a filter

16 SOLIDS 4 Sources of Error –Accurate analytical balance –Sample homogeneity –Accuracy of T in oven –Clean glassware between analyses –Simple to do; easy to mess up 4 TS + TSS: Dry to º C 4 TDS: Dry to º C

17 DISSOLVED OXYGEN (DO) 4 Electrometric (Electrode ) –More common –Rate of diffusion of molecular O 2 across membrane

18 DISSOLVED OXYGEN (DO) 4 Winkler –More precise & reliable –Add Mn +2 + strong base, DO oxidizes Mn +2 to higher ordered Mn(OH) x+2. Add I - /H + ; Mn goes back to Mn +2 & equivalent I - is liberated. Titrate with (S 2 O 3 ) -2 w/starch indicator. (S 2 O 3 ) -2 must be standardized at least quarterly. I - takes the place of O -2 –Interferents include oxid.(+) & red. (-) agents; options include adding azide [(NO2) - ], & permanganate [Fe +2 ] –Fix on-site & run w/i 8 hrs.

19 INORGANIC NON-METALLIC CONSTITUENTS

20 ANIONS BY ION CHROMATOGRAPHY 4 HPLC w/conductivity detection (300.0, 4110) 4 Multi-element g/l sensitivity 4 Anions: F -, Cl -, Br -, (NO2) -, (NO3) -, (SO4) -2, (PO4) -3 and others 4 F - often difficult to quantify; can be done 4 Works well for DW, WP and SHW extracts

21 ION CHROMATOGRAPHY

22 HALOGEN IONS (F -, Cl -, Br -, I - ) 4 Analytical Options –Colorimetric –Titrimetric –IC –Ion-Selective Electrodes (ISE) (SM Method 4500) DW only

23 ION SELECTIVE ELECTRODES 4 Measure the activity of free ions in solution 4 Interferences known & controllable 4 Must control T & ionic strength 4 Can measure halides, S -2, NH 3 and (CN) - 4 Electrode types: –Crystalline –Gas Sensing

24 CYANIDE (CN - ) 4 All CN groups that can be determined as CN - 4 Total Cyanide measures all free & bound CN - 4 Cyanide Amenable to Chlorination includes free CN - & all CN - complexes that are dissociable such as metal-CN complexes. This requires a much more rigorous digestion. –Oxidation of organo-CN complexes can cause problems; keep chlorinated fraction in the dark

25 CYANIDE (CN - ) 4 Both require sample distillation; collect as HCN 4 For CN - amenable to chlorination, divide sample in 2, and subtract CN - found in dechlorinated & chlorinated fractions 4 Measurement Options –Titration –Colorimetry –ISE

26 NITROGEN SPECIES 4 Forms of N to be measured: –(NO 3 ) - –(NO 2 ) - –NH 3 –Organic N 4 Organic N = (NO 3 ) - + (NO 2 ) - 4 NH 3 : generally low in GW because of particle absorption

27 AMMONIA (NH 3 ) 4 As per Federal regulations,a preliminary distillation step MUST be performed unless you can demonstrate the absence of interferences for YOUR effluent 4 Measurement Options –Titration –ISE –Phenate w/ or w/o automation

28 AMMONIA (NH 3 ) 4 Titration –Only used after distillation –H 3 BO 3 added to decrease hydrolysis of organo-N species –Titrate w/std. H 2 SO 4 ; end-pt. either w/indicator or electrometrically –Useful below 5 mg/L 4 ISE –Gas-permeable membrane to measure NH 3(aq) & (NH 4 ) + converted to NH 3(aq) by pH adjust. to 10-11

29 AMMONIA (NH 3 ) 4 Phenate –Indophenol (VERY blue) is made from reaction between NH 3, (ClO3) - & phenol catalyzed by nitroprusside –Measure 640 nm –Interfering Ca & Mg can be complexed –Can be easily automated –RSDs much better than titrimetry or ISE

30 (NO 2 ) - & (NO 3 ) - 4 Both can be done by IC 4 (NO 2 ) - can also be done by spectrophotometry 4 (NO3) - –UV-Spec. –ISE –Cd Reduction

31 ORGANIC (KJELDAHL) N 4 Measures N as N -3; Kjeldahl N is the same as organic N. Digest sample, convert to NH 3, and measure as per NH 3 options. 4 Does not measure e.g., azide, azo, nitro, nitoso, nitrite or nitrate N species 4 Macro: low [NH 3 ], requires larger sample volume (500 ml.) Micro: higher [NH 3 ]

32 PHOSPHOROUS SPECIES 4 P analyses consist of 2 steps –Digestion converts phosphorous to orthophosphate –Colorimetric determination 4 Reactive P (Orthophosphate): respond to colorimetry w/o hydrolysis or oxidation 4 Organic P: Fraction convertible to orthophosphate by destruction of organic matter

33 SULFITE (SO 3 ) -2 4 Occurs in boilers & feedwaters & treatment plant effluents 4 Method Options –Iodometric: KI titration w/starch indicator –Colorimetric: (easier) Reaction w/1,10- phenanthroline & vis. 510 nm.

34 SULFATE (SO 4 ) -2 4 Method Options –IC (BEST CHOICE) –Turbidimetry: BaSO 4 ppct. light scattering is measured (MOST COMMON) –Gravimetry: (Ppct. as BaSO 4 ) –Titrimetry: xs. Ba is complexed w/methylthymol blue to yield blue color

35 SULFIDE (S -2 ) 4 Total S -2 includes both H 2 S & HS - as well as acid-soluble metallic sulfides; [S -2 ] very low 4 There are several qualitative tests 4 Quantitative Methods: I - oxidizes S -2 / H + –Titration: OK if [S -2 ] > 1 ppm –Iodimetric –ISE

36 AGGREGATE ORGANIC CONSTITUENTS

37 BOD 4 Measures molecular O 2 used during the biochemical degradation of organic matter (C) in water 4 Usually applied to determine waste loadings to treatment plants & efficiency of control measures 4 w/o inhibitor is added, can also measure O 2 s ability to oxidize N species 4 5 day test: BOD day test: BOD day test: UBOD

38 BOD 4 Fill sample to overflow & seal airtight 4 Incubate for fixed time 4 Measure DO initially end 4 BOD = Final [DO] - Initial [DO] 4 See SM for working ranges & DLs

39 BOD 4 Do a series of dilutions for sample analyses 4 Some samples may need to be seeded with microorganisms –high pH, chlorination, high T 4 CBOD (carbanaceous demand0 is used where nitrification inhibitor is employed 4 Holding time is 48 hrs.

40 COD 4 Amt. of O 2 that certain organisms & chemicals will consume 4 Interferences –[Cl - ] > 1000 mg/l –VOCs might be lost prior to oxidation 4 Method Summary –Most organics & oxidative inorganics are oxidized by addition of K 2 Cr 2 O 7 / H 2 SO 4 –xs. (Cr 2 O 7 ) -2 is titrated w/Fe(NH 4 ) 2 (SO 4 ) 2.6H 2 O

41 TOTAL ORGANIC CARBON (TOC) 4 Better expression of organic content than BOD or COD 4 TOC is independent of the ox. state of the organic matter and does not measure H or N 4 Organic molecules C CO 2

42 TOTAL ORGANIC CARBON (TOC) 4 Measurement Options –Non-Dispersive IR (5310B) Sample is combusted Measures total C; inorganic C must be subtracted to give TOC –Reduce to Methane (5310C) Measure by dedicated FID analyzer –Wet-Oxidative (5310D) Oxidized with KHSO 4 in autoclave Resulting CO 2 measured by non-dispersive IR –UV-Persulfate

43 GENERAL RULE 4 COD > BOD > TOC

44 TOX (DOX) 4 Measures total dissolved organic matter in H 2 O 4 Contributing compounds include: THMs, org. solvents (TCE), halogenated alkanes, alkenes, & pesticides, PCBs, chlorinated aromatics (C 6 H 4 Cl 2 ), chlorinated humics 4 Does not tell you ANYTHING about the structure or nature of the chlorinated organic(s); does not detect organo-F species

45 TOX (DOX) 4 Measurement consist of 4 steps –Dissolved organic matter is separated from inorganic halides by adsorption onto activated C –Inorganic halides are removed by (NO3) - displacement –Pyrolyze activated C C CO 2 Bound halogens HX –HX species by Ag + titration

46 METHOD REFERENCES 4 Standard Methods for the Examination of Water and Wastewater, 19th Edition 4 Code of Federal Regulations –Part 136: DW –Part 141: WP 4 American Society for Testing and Materials, Section 11, Volumes & 11.02

47 OQA CONTACTS 4 Analyze Immediately –Kathleen Kinsella –Michael DiBalsi Inorganics –Stu Nagourney –Michelle Mooney Aggregated Organics –Dr. Michael Miller General QA/QC –Marc Ferko


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