Yes, PROBEST water quality sensors require regular calibration. The calibration cycle varies by sensor type. It is generally recommended to calibrate every two weeks or based on usage frequency to ensure data accuracy.

Answer: All genuine, high-quality PROBEST online digital water quality monitoring sensors meet the IP68 waterproof standard.
They are designed for long-term underwater operation and can function reliably at depths up to 10 meters.

All PROBEST water monitoring analysis sensors are with the RS485 (MODBUS-RTU) signal output.
This industry-standard, stable transmission protocol offers strong compatibility and enables seamless integration with various monitoring systems such as SCADA systems and smart water management platforms.
No additional conversion modules are required; simply connect according to the standard wiring sequence to achieve real-time data upload.

Answer: By utilizing the fluorescence excitation properties of phycocyanin in cyanobacteria, a specific wavelength light beam excites the phycocyanin.
The intensity of the emitted fluorescence is then measured to accurately calculate the cyanobacteria concentration.

Yes. Water purifier filter cartridges have a limited lifespan. Failure to replace them over time can lead to reduced filtration effectiveness and even bacterial growth. It is recommended to test the output water quality every 6-12 months to determine if the filter cartridge needs replacement.

Chlorine odor: This is typically residual chlorine from disinfection at the water treatment plant, which is normal. Boiling the water will eliminate the odor, and testing is generally unnecessary.

Fishy or earthy odor: This may indicate aging pipes, contamination in secondary water supply tanks, or the proliferation of algae and microorganisms in the water. Testing for microbial and organic indicators is recommended.

Microbiological indicators: Such as total bacterial count and E. coli. Exceeding standards may cause diseases like diarrhea and gastroenteritis.

Heavy metal indicators: such as lead, mercury, and arsenic. Long-term exposure can damage organs like the liver and kidneys, with greater impacts on children's development.

Physical and chemical indicators: pH (normal range 6.5-8.5), residual chlorine (end-of-tap residual chlorine ≥0.05mg/L to ensure disinfection effectiveness), hardness (excessive levels may cause scale buildup, affecting taste and appliance lifespan).

Sampling containers: Use clean, uncontaminated dedicated containers. Avoid using ordinary plastic or glass bottles (residual substances may affect results).

Sampling timing: For tap water testing, open the faucet and let water run for 5-10 minutes after water supply resumes before sampling to avoid interference from stagnant water in pipes.

Timeliness of submission: Submit samples promptly after collection (generally within 24 hours), especially for microbial testing, to prevent sample degradation.

Simple Tools: Use home water testing kits (to measure basic indicators like pH, residual chlorine, and hardness). These are easy to operate but have limited accuracy.

Professional Testing: Engage a third-party testing agency that provides on-site sampling services.
They can test comprehensive indicators such as heavy metals, microorganisms, and organic compounds, delivering more accurate results.

Domestic Scenarios: Testing tap water and drinking water safety to ensure freedom from harmful microorganisms or heavy metals.

Industrial Scenarios: Testing industrial water (such as cooling water and production water) to prevent equipment corrosion or product quality issues.

Environmental Scenarios: Monitoring water quality in rivers, lakes, seas, and groundwater to assess pollution levels and ecological health.

 

Water quality analysis is the process of using specialized methods to test physical, chemical, and biological indicators in water to assess whether the water meets usage standards (such as for drinking, industrial, agricultural, etc.).

Xiong Yi, Chief Economist for China at Deutsche Bank Group, stated in a research report that the renminbi exchange rate may reach a trend inflection point as trade tensions ease. Deutsche Bank Research forecasts that by the end of 2026, the RMB is expected to appreciate to 6.7 against the US dollar.

The firm believes factors such as seasonal export patterns, low short positions in offshore RMB against the dollar, and improving inflation expectations could drive the RMB back toward its long-term appreciation trend.

National Standard Methods for Determining Total Nitrogen in Water

The primary national standard methods for determining total nitrogen in water are as follows:

 

“Water Quality - Determination of Total Nitrogen - Potassium Persulfate Alkaline Digestion and Ultraviolet Spectrophotometric Method” (HJ 636-2012)

 

Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.

Principle: At 120-124°C, alkaline potassium persulfate solution converts nitrogen in nitrogen-containing compounds to nitrate. Absorbance is measured at wavelengths of 220 nm and 275 nm using ultraviolet spectrophotometry. The relationship between corrected absorbance and total nitrogen content is calculated.

Detection Range: 0.2–7 mg/L, detection limit 0.05 mg/L.

Interferences and Elimination: Iodide ions, bromide ions, hexavalent chromium ions, and trivalent iron ions may cause interference. These can be eliminated by dilution or addition of hydroxylamine hydrochloride solution.

Water Quality - Determination of Total Nitrogen - Gas Phase Molecular Absorption Spectroscopy (HJ 199-2023)

 

Scope of Application: Surface water, groundwater, domestic sewage, industrial wastewater, and seawater.

Principle: Using alkaline potassium persulfate as an oxidant, nitrogen in the sample is oxidized to nitrate nitrogen via high-temperature high-pressure digestion or online UV digestion. It is then reduced to nitric oxide by titanium trichloride and measured using a gas phase molecular absorption spectrometer.

Detection Range: Detection limit is 0.05 mg/L for both high-temperature high-pressure digestion and online UV digestion; lower limit of quantification is 0.20 mg/L.

Interferences and Mitigation: Hexavalent chromium, trivalent iron, and high concentrations of organic matter may cause interference. Mitigate by dilution or optimizing digestion conditions.

Water Quality - Determination of Total Nitrogen - Flow Injection-Hydrochloric Acid-Naphthylenediamine Spectrophotometric Method (HJ 668-2013)

 

Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.

Detection Range: 0.12–10 mg/L.

Water Quality—Determination of Total Nitrogen—Continuous Flow-Hydrochloric Acid Naphthylenediamine Spectrophotometric Method (HJ 667-2013)

 

Scope of Application: Surface water, groundwater, industrial wastewater, and domestic sewage.

Detection Range: 0.16–10 mg/L.

Among the above methods, HJ 636-2012 and HJ 199-2023 are currently the most commonly used laboratory determination methods. The specific selection may be determined based on sample type, detection range, and laboratory conditions.

Interrelationships Among Water Testing Parameters in Environmental Monitoring

Relationship Between Hexavalent Chromium and Total Chromium

 

Chromium in water typically exists as trivalent and hexavalent forms, which can convert under certain conditions. Total chromium is the sum of trivalent and hexavalent chromium. Therefore, for the same water sample, the following logical relationship holds:

 

Total Chromium > Hexavalent Chromium

 

Relationship Between Sulfides and Heavy Metals

 

In the same water sample, high sulfide concentrations correlate with lower concentrations of heavy metals (Cu, Pb, Zn, Cd, etc.). However, this relationship may not hold if heavy metals exist in complexed forms.

 

Relationship Between Total Bacteria Count, Coliform Bacteria, and Fecal Coliform Bacteria

 

Coliform bacteria represent only one population among bacterial species and have limited contamination pathways. Long-term testing indicates that samples detecting coliform bacteria also detect total bacteria count. Conversely, samples with high total bacteria counts do not necessarily detect total coliform bacteria. Fecal coliform bacteria belong to the total coliform group and are detected at 44.5°C, which is higher than the 37°C detection temperature for total coliform bacteria. Therefore, fecal coliform values are typically lower than total coliform values, i.e., fecal coliform value < total coliform value.

Interrelationships Among Water Quality Parameters in Environmental Monitoring

Relationship Between Nitrite Nitrogen and Total Nitrogen

 

Nitrogen primarily exists in aquatic environments as nitrate, nitrite, ammonia, and organic nitrogen. Therefore, total nitrogen should equal the sum of nitrite nitrogen and organic nitrogen. For the same water sample, the following logical relationships hold:

 

Total Nitrogen > Ammonia Nitrogen Total Nitrogen > Sum of Ammonia Nitrogen, Nitrate Nitrogen, and Nitrite Nitrogen

 

Interrelationships Among Water Quality Parameters in Environmental Monitoring

Relationship Between Water Temperature and Dissolved Oxygen

 

The distribution and variation of dissolved oxygen in water result from the combined influence of temperature, biological activity, chemical processes, and various physical phenomena. Overall, it is primarily controlled by water temperature, exhibiting pronounced seasonal fluctuations. Dissolved oxygen levels in water show a negative correlation with temperature and generally should not exceed the saturation level corresponding to the prevailing water temperature.

 

Interrelationships Among Water Quality Parameters in Environmental Monitoring

Relationship Between Nitrogen Compounds and Dissolved Oxygen

 

Since the forms of nitrogen present in the environment change with variations in environmental conditions, particularly influenced by the concentration of dissolved oxygen in water bodies, nitrate nitrogen and ammonia nitrogen cannot be high simultaneously. Generally, in water bodies with high dissolved oxygen, the concentration of nitrate nitrogen is higher than that of ammonia nitrogen, and conversely, the concentration of ammonia nitrogen is higher than that of nitrate nitrogen. Nitrite nitrogen concentrations show no significant correlation with these parameters.

Interrelationships Among Water Testing Parameters in Environmental Monitoring

Relationship Between Petroleum Hydrocarbons and CODcr

 

Petroleum hydrocarbons are organic pollutants that can be oxidized by potassium dichromate. Higher concentrations of petroleum hydrocarbons correlate with elevated CODcr values, though no fixed correlation coefficient exists.

Interrelationships Among Water Quality Parameters in Environmental Monitoring

Relationship Between TOC, CODCr, and CODMn
 

Total Organic Carbon (TOC) is a comprehensive indicator representing the total organic matter content in water expressed as carbon content. TOC employs combustion methods to fully oxidize organic matter, directly indicating the degree of organic pollution in water bodies. TOC, CODCr, and CODMn are all indicators measuring organic pollution levels in water. Test results from domestic sewage and industrial wastewater across various sectors show significant correlations between TOC and both CODCr and CODMn. Theoretically, CODcr expresses oxygen consumption in terms of oxygen (O₂) consumed, while TOC expresses it in terms of carbon (C). The ratio between them is O₂/C = 32/12 = 2.7. For specific water bodies, this conversion factor is sufficient. However, due to variations in water composition and organic content across different water bodies—and even within the same body of water due to seasonal changes, inflow conditions, production processes, and raw material variations—the conversion relationship between these parameters must be experimentally determined.

Probest with the PUVCOD900-TOC, PCM200-CODCr, PCM200-CODMn, PUVCOD-900-COD water quality monitoring Analysis. 

Interrelationships Among Water Testing Parameters in Environmental Monitoring

Total Dissolved Solids and Total Hardness

 

Since water contains eight primary ions, including Ca²⁺ and Mg²⁺, the total hardness of a water sample is defined as the sum of carbonate hardness and non-carbonate hardness. Non-carbonate hardness must be determined. When total hardness is measured using the CO DMn (acidic method), CO Dcr > BOD₅.