Lead

Method: Hach LeadTrak Fast Column Extraction Method
Range: 5-150 ppb lead in water
Kit includes a 10 mg/L lead standard = 10,000 ppb lead.
Also need distilled or deionized water.

 Lead Vol H2O Vol 10 mg/L
 0 ppm100 mL  0.0 mL
 50 ppm 99.5 mL 0.5 mL
 100 ppm 99.0 mL 1.0 mL 
 150 ppm 98.5 mL 1.5 mL


Test 1: 0 and 50 ppb
Sample 1 was a "blank" 0 ppb sample which was just 100 mL of distilled water.  
Sample 2 was a 50 ppb solution prepared by adding 0.5 mL of the lead 10 mg/L standard to 100 mL distilled water.
Followed the LeadTrak Fast Column procedure for both samples.
 
In the first test, ended up blanking the colorimeter with water and measuring absorbance at 470 nm with the samples before and after decolorizing solution was added.

 Sample Before After Change
 0 ppb 0.42  0.40 0.02
 50 ppb 0.47 0.40 0.07


Test 2: 0 and 150 ppb
Sample 1 was a "blank" 0 ppb sample which was just 100 mL of deionized water.  
Sample 2 was a 150 ppb solution prepared by adding 1.5 mL of the lead 10 mg/L standard to 100 mL deionized water.
Followed the LeadTrak Fast Column procedure for both samples.
 
In the second test, I took the 25 mL eluted sample and poured 10 mL into 2 tubes for each sample. To one of the tubes, added 3 drops of decolorizing solution. The sample with the decolorizing solution was used to zero the colorimeter and the sample without decolorizing solution was measured. 

 Sample Absorbance
 0 ppb 0.03 
 150 ppb 0.23

Test 3: 0 and 150 ppb repeated
Same method as Test # 2. Measured absorbance at 470 nm in the colorimeter and also using an Ocean Optics Spectrophotometer.

 Sample Absorbance @ 470 nm Absorbance (spec)
@ 477 nm
 Absorbance (spec)
@ 470 nm
 0 ppb 0.03  0.018 0.028
 150 ppb 0.20
 0.432 0.328

Test 4: 0, 50, 100 and 150 ppb calibration curve
Same method as usual. Measured absorbance at 470 nm in the colorimeter and and also using Ocean Optics Spectrophotometer.
Note, for the Ocean Optics, data was less noisy as we used averaging (n=10) in the ocean optics software.


 Sample Absorbance @ 470 nm Absorbance (spec)
@ 477 nm
 Absorbance (spec)
@ 470 nm
 0 ppb 0.02 0.020 0.026
 50 ppb 0.07 0.141 0.109
 100 ppb 0.14 0.284 0.213
 150 ppb 0.21
 0.460
 0.351

Test 5: 100 ppm standard and tap water


 Sample Absorbance @ 470 nm Absorbance (spec)
@ 477 nm
 Absorbance (spec)
@ 470 nm
 100 ppb 0.14 0.281 
 tap water 0.01 -0.001 
 standing water 0.01
 0.017
 


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