Reagent Strips for the Detection ofHigh Range Total Alkalinityand Phosphatein Various Water Samples andCoolants using Handheld PhotometersBy Balaji TatineniAbstract 2370 – 2 Thursday March 21, 8:20 am
Total Alkalinity !• Alkalinity is a measure of the “acid neutralizing capacity”• Important compounds for Alkalinity are:H+ Hydrogen ion (acid)OH- Hydroxide ion (base)H2CO3 Carbonic acidHCO3- Bicarbonate ionCO32- Carbonate ionCaCO3 Calcium Carbonate (Calcite)CaMg(CO3)2 Dolomite lime
Continuation….Low alkalinity can result in rapid pH changes, if acid or baseenters the waterMost streams and lakes of western Oregon and Washingtonhave low alkalinity due to the volcanic geology of the CascadeMountain Range --- less time to interact with the geologyWastewater have higher alkalinity – due to higherconcentrations of nutrients and ionsAlkalinity in streams - influenced by rocks and soils, salts, certainplant activities, and certain industrial wastewater dischargesMeasured in mg/l or ppm
Typical Alkalinity ranges Sample Value, mg/L CaCO3Rain Water <10Typical Surface Water 20-200Surface water inregions with alkalinesoils100-500Ground water 50-1000Sea water 100-500
Total Alkalinity Testing • Important compounds that determine alkalinity – Carbonateand Bicarbonate ions • Types of Alkalinity: o Phenolphthalein Alkalinity: called as Bicarbonate alkalinity and present for solutions above pH 8.3. Phenolphthalein indicator color changes from pink to colorless with the addition of acid Many water samples have little or no phenolphthalein alkalinity o Total alkalinity - the ﬁnal endpoint for alkalinity titration. At pH 4.5 all carbonate and bicarbonate ions are converted to carbonic acid
Continuation-----Double endpoint titration using a pH meter (or pH "pocket pal")and a digital titrator or buret is generally used.Titration method uses the addition of small, precise quantities ofsulfuric acid (the reagent) to the sample until the samplereaches a certain pH (known as an endpoint). The amount ofacid used corresponds to the total alkalinity of the sample.Sulfuric acid converts the three main forms of alkalinity(bicarbonate, carbonate, and hydroxide) to carbonic acid inthese reactions.This method is tedious and not user friendly for field sampleanalysis
Total Alkalinity – Reagent strips• Our current reagent strip detects TotalAlkalinity from 1 to 320 ppm• We developed chemistry usingvarious pH sensitive dyes and acids toextend the above Total Alkalinityrange.
Total AlkalinityReagent Test Overview• New formulation has increased the Total Alkalinity range from1-320 to 1-800 ppm• The limit of detection is (3SD) is 8.58 ppm• Accuracy of the method is ± 6%• No Interferences• Performance of the strips were validated for drinking,pool, coolant, boiler and sea water
Total Alkalinity – SpectrasReaction of Alizarin red S with variousconcentrations of Total Alkalinity00.20.40.60.81400 450 500 550 600 650 700Total Alkalinity, ppmAbsorbance0 ppm50 ppm100 ppm200 ppm300 ppm400 ppm500 ppm600 ppm700 ppm800 ppmCalibrationplot - AlizarinredSwithvariousconcentrationsof Total Alkalinityy =0.0008x+0.0424R2=0.983300.10.20.30.18.104.22.168.80 100 200 300 400 500 600 700 800Total Alkalinity, ppmAbsorbance
Phosphate• Phosphorus present 0.12% in the earth’s crust"• Human bones and teeth contain calcium phosphate"• Muscle, nerves and brains of animals contain complex organiccompounds of phosphorus"• Red phosphorus is used to manufacture of safety matches andfertilizers"• Majority of phosphate water contamination problems occur in thepool and in the ground"
Phosphate - Water• Lawn runoff "• Rain water "• Leaves and debris (soil and rock)"• Swimming pool bathers (sweat and urine)"• Pool treatment chemicals"
Algae and Phosphate• If algae is observedphosphate is present• Chlorine levels controlalgae growth• Sewage (waste) watercontains high levels ofalgae if not treatedproperly
Phosphate TestingLaboratory Instruments:Spectroscopic, Chromatographic, etc• Costly to operate• Not user friendly• Time consuming• Increased sample prep time• Most approved by various Governments
Phosphate TestingPortable Instruments:Hand Held Photometers• Cost effective• User friendly• Fast results• Used in field and real time monitoring• Most approved by various Governments
• New formulation has increased the Phosphate range from0-4 ppm to 0-6 ppm• The limit of detection is (3SD) is 0.18 ppm• No interferences• Accuracy ± 3%• Performance of the strips were validated for drinking,pool, coolant, boiler and sea waterPhosphateReagent Test Overview
Press READ to start the count down timer and dipan eXact® Strip Micro PO4 Phosphate for 20seconds then remove and discard strip.
The meter automatically starts the count uptiming for 120 seconds and reads thesample for PhosphateTesting cap is not necessary for accurate readings, the meter designovercomes ambient light interference.
eXact® Micro Photometers Benefits• Safe to use with no glass, powders or tablets to break• Lab quality results at 0.01 ppm (mg/L) precision• Affordable and uses safe chemistry• Quick Non-Technical Procedure• Accurate results with fewer steps than competitive kits
eXact® Micro Photometers Benefits• Uses patented reagent delivery system• Reagent strip provides smooth and precise sample dispersion• No suspended solids are left in the sample vial to adverselyaffect results especially in cold water
• We developed reagent strips for the detection of High RangeTotal Alkalinity and Phosphate• We applied the strip technology and testing method for oureXact Micro photometers• The reproducibility, precision and accuracy were very good• Applied to various water samples• We have also developed High Range Total Hardness andMagnesium Hardness strips
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