Do you know the difference between TVOC, VOC and VOCs?

VOC
Definition: volatile organic compounds. Generally, NMVOC (non-methane volatile organic compounds) is used to refer to VOCs at home and abroad. Because the concentration of methane in VOC is high (volume ratio 1.76ppm, mass ratio 0.97ppm, concentration ratio 1.35mg/m3), it will dilute the influence of other VOCs.
There are certain flaws in the VOC indicator:
1. There are many types of VOCs, but it is impossible to include all volatile organic compounds during monitoring and supervision. Therefore, some indicators have been used in China to characterize VOCs such as VOCs, TVOCs, non-methane total hydrocarbons and hydrocarbons.
2. The most important sources of VOC pollution are fixed source combustion, transportation sources, solvent applications, chemical production and storage, petroleum storage and transportation, refining, and hybrid sources. The components of each source (alkanes, alkenes, aromatics, carbonyls, halogenated hydrocarbons, and others) vary, but the VOC index is only superficially added to various volatile organic matter and cannot be characterized by various components. the difference.
VOCs
The original intention of the VOCs indicator is to analyze the results of various components by analyzing the composition of VOCs.
Definition: Volatile contaminants are those with boiling points below 260 ° C. They have a high vapor pressure in the air and are easily volatilized in gaseous form in ambient air - Air and Exhaust Gas Monitoring Methods (Fourth Edition) )
Vapor pressure greater than or equal to 10 Pa at 293.15 K, or all organic compounds (excluding methane) with corresponding volatility under specific conditions, abbreviated as VOCs. - "Tianjin Industrial Enterprises Volatile Organic Compounds Emission Control Standards" (DB12524-2014)
Standards: Environmental quality standards are not available; emission standards have no national standards for the time being, only local standards and industry standards, such as “Tianjin Industrial Enterprises Volatile Organics Emission Control Standards” (DB12 524-2014).
Monitoring methods: Determination of volatile organic compounds in ambient air, tank sampling/gas chromatography-mass spectrometry (HJ759-2015), sampling air bag method for volatile organic compounds from fixed pollution sources-HJ 732-2014, etc.
TVOC
Definition: A non-polar column (with a polarity index of less than 10) was analyzed using a Tenax GC or Tenax TA sample with a retention time of volatile organic compounds between n-hexane and n-hexadecane. - "Indoor Air Quality Standards" (GB/T18883-2002)
The TVOC indicator appears in the Indoor Air Quality Standard (GB/T18883-2002). It is not an indicator of the sum of all VOCs, but an indicator of the common VOC addition in the room.

Urine Test Strips

The physical examination items of pet urine include urine volume, urine color, odor and transparency. Pathological examination includes routine urine examination, urine sediment examination and some special examinations.
Pet urine can be collected through catheterization, external bladder puncture, and natural urination methods.
Urine should be collected in less than 1 hour in summer and 2 hours in winter.
This product can be used for qualitative/semi-quantitative detection of 14 chemical indexes in human urine, including glucose, bilirubin, ketone body, specific gravity, occult blood, pH, protein, urochologen, nitrite, white blood cells, ascorbic acid, creatinine, calcium and trace albumin.

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