Kyoritsu WAK-PO4 Total Phosphorus Colorimetric Test Kit
| Brand | Kyoritsu |
|---|---|
| Origin | Guangdong, China |
| Manufacturer Type | Authorized Distributor |
| Product Category | Domestic |
| Model | WAK-PO4 Total Phosphorus Colorimetric Test Kit |
| Price Range | USD 34–39 |
| Measured Parameter | Total Phosphorus |
| Instrument Type | Laboratory |
| Measurement Principle | Ascorbic Acid-Molybdate Blue Colorimetry |
| Measurement Range | 0.2–10 mg/L as P |
Overview
The Kyoritsu WAK-PO4 Total Phosphorus Colorimetric Test Kit is a standardized, pre-calibrated laboratory-grade reagent system engineered for rapid, reliable quantification of total phosphorus (as elemental P) in aqueous samples. It implements the internationally recognized ascorbic acid–molybdate blue colorimetric method (based on ISO 6878:2004 and APHA Standard Method 4500-P E), wherein orthophosphate—liberated from all phosphorus-containing species via high-temperature persulfate digestion—is reacted with ammonium molybdate and potassium antimonyl tartrate under acidic conditions, followed by reduction with ascorbic acid to yield a stable, intensely colored phosphomolybdenum blue complex. Absorbance is measured at 880 nm using a standard spectrophotometer or dedicated photometer, enabling direct concentration determination via a built-in calibration curve traceable to NIST-traceable phosphate standards.
Key Features
- Premixed, stabilized reagents in sealed, light-protected glass vials—minimizing operator error and ensuring batch-to-batch consistency
- Pre-marked volumetric fill lines on each reaction tube for precise 10 mL sample aliquots and reagent addition
- Digestion-compatible design: validated for use with standard block digesters (e.g., Hach DRB200) operating at 120–125 °C for 30 minutes
- Stable color development: absorbance remains constant for ≥60 minutes post-reduction, accommodating sequential analysis of multi-sample batches
- Low interferences: optimized matrix tolerance for common anions (Cl⁻, NO₃⁻, SO₄²⁻ ≤ 1000 mg/L) and cations (Ca²⁺, Mg²⁺ ≤ 200 mg/L); optional masking agents available for high-iron or high-silica samples
- Compliant with GLP documentation requirements: each kit includes lot-specific certificate of analysis (CoA) with expiration date, sensitivity (detection limit: 0.12 mg/L P), and linearity data (R² ≥ 0.999 over 0.2–10 mg/L)
Sample Compatibility & Compliance
The WAK-PO4 kit is validated for use with raw and treated wastewater, surface water (rivers, lakes, canals), industrial effluents (including electroplating, food processing, and fertilizer manufacturing discharges), and educational laboratory samples. It meets the analytical performance criteria outlined in EPA Method 365.4 (for wastewater) and ISO 6878:2004 (for environmental waters). All reagents are manufactured under ISO 9001-certified quality management systems; final packaging adheres to UN transport regulations for Class 8 corrosive substances (UN2796). The kit supports audit-ready compliance with ISO/IEC 17025:2017 clause 5.4.2 (method validation) and facilitates traceability per FDA 21 CFR Part 11 when paired with compliant data acquisition software.
Software & Data Management
While the WAK-PO4 kit itself is a manual wet-chemistry method, it integrates seamlessly with digital workflows. Spectrophotometers equipped with Kyoritsu’s optional WAK-Link™ firmware (v2.3+) support direct calibration curve import, automatic concentration calculation, and CSV export with embedded metadata (operator ID, sample ID, digestion time, instrument serial number). Raw absorbance values and calculated concentrations are timestamped and stored with audit trail functionality—enabling full compliance with GLP/GMP data integrity requirements. For laboratories operating under regulated environments (e.g., municipal water utilities certified to DWA-203 or EU Directive 2000/60/EC), the kit’s documented uncertainty budget (±4.2% RSD at 1.0 mg/L P) satisfies reporting thresholds for routine monitoring programs.
Applications
- Regulatory compliance monitoring for discharge permits (e.g., NPDES, IPPC)
- Process control in municipal wastewater treatment plants (influent, effluent, digester supernatant)
- Source tracking and load estimation in watershed management studies
- QA/QC verification of automated online phosphorus analyzers (e.g., UV-digested continuous flow systems)
- Undergraduate and graduate teaching labs—supporting curriculum-aligned experiments on eutrophication, nutrient cycling, and analytical method validation
- Field-deployable verification: when used with portable VIS spectrophotometers (e.g., Hach DR390, Lovibond MD600), enables same-day data capture during environmental inspections
FAQ
What digestion protocol is required prior to WAK-PO4 analysis?
Standard persulfate oxidation at 120–125 °C for 30 minutes is mandatory to convert condensed phosphates, organophosphates, and particulate-bound P into orthophosphate.
Can the kit be used for seawater or brackish samples?
Yes—with dilution and salinity correction: samples with >5000 mg/L TDS require 1:2 dilution with deionized water and application of a matrix-matched calibration curve.
Is the reagent shelf life affected by storage temperature?
Unopened kits retain full potency for 24 months when stored at 2–8 °C; room-temperature storage (≤25 °C) reduces shelf life to 12 months—both conditions are specified on the CoA.
Does the kit include digestion reagents?
No—WAK-PO4 contains only colorimetric reagents. Persulfate digestion tablets or solutions must be sourced separately (e.g., Kyoritsu WAK-DIGEST-PS series).
How is method accuracy verified?
Each production lot undergoes independent verification using CRM reference materials (NIST SRM 2784 and LGC 6012) with recovery rates maintained between 96.5–103.2% across the 0.2–10 mg/L range.
