Test Tube Format Phosphate Test Kits

Test Tube Format Phosphate Test Kits

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This kit is supplied complete with all necessary reagents except for HPLC water.  Use this kit for quantitative phosphate analysis of essentially any aqueous sample, from wastewater to soil and plant extracts.  Simply extract solid samples using HPLC water before analysis.  This test tube format kit is to be used with your UV capable spectrophotometer capable of reading absorbance at 360nm.    

Quantitates Phosphate in Complex Mixtures

Choose kit type using choices below, or contact us for a custom kit fit for your application:

  • Standard Range (5 ppm - 20 ppm Phosphate) or Low Range (0.5 - 5 ppm Phosphate)

  • Reagents for 25 Samples or 100 Samples

PNP Assay

When reaction is complete, the purine product yields an increase in absorbance at 360 nm in equal molar ratio to the inorganic phosphate in the reaction mixture.  Using the equation of the linear regression line fitted to the set of phosphate standards, the phosphate concentration a sample can easily be determined.  

Additional Information


Number of tests - Low Range ID - Standard Range ID

25 tests - PTK-TTLR-25 - PTK-TTSR-25

100 tests - PTK-TTLR-100 - PTK-TTSR-100

Related Documents

PNP Reductase Storage and Reconstitution

PNP Specification Sheet *Coming Soon*

SDS for Phosphate Test Kits

In addition to this kit, you will need a graduated cylinder, variable pipetters, a test tube vortex-type mixer, spectrophotometer capable of measuring 340 nm with UV compatible cuvettes, clean and phosphate-free 13 x 100mm test tubes, a timer, HPLC water, and ice.

NECi Recombinant PNP catalyzes Ortho-Phosphate dependent transfer to ribose with release of free purine base.  One unit produces 1 µmole of hypoxanthine from inoside per minute, at pH 8.0 and 22°C.


  • CAS #: 9030-21-1
  • Temperature Range in Assay: 15 – 45°C
  • Physical Form:  Freeze-dried protein glass
  • Expected Purity Range: 5 - 15 units/mg protein
  • Recombinantly manufactured in Escherichia coli: Consistent, Reliable
  • Utilizes MESG as the co-factor to accurately quantify phosphate in a sample
  • Small sample size in relation to total assay volume
  • Little sample preparation required
  • High specificity reduces false positives

Stability Information:

  • Shelf life in freeze-dried, vacuum-sealed packets: Stable indefinitely at -20°C or lower;  Min 24 months at 4°C; Min 12 months at RT (20 – 25°C); 1 week at 30-40°C
  • Shelf life in vials:  12 months + stored cool (4°C or below) and desiccated
  • Shelf life in solution:  Working solution in buffer at 1 U/ml:  > 12 hours at RT and below.  Working solution containing 25% Glycerol:  minimum one year at -20°C.

For more detailed information about this kit, please view the instruction sheet.

For technical support regarding kits, contact tech@nitrate.com

For inquiries regarding orders, or to request a custom quotation for international orders, contact sales@nitrate.com

Kits purchased to use in classroom demonstrations or projects may be eligible for discounts. Complete survey HERE

Call 1-888-NITRATE or (906)-296-1130 for answers, support, and to make comments.