Features of the instrument:

Provides absolute calibrated concentrations for H2O2 and relative values for organic peroxides. Fully automated operation using internal micro controller. Automated calibration using internal H2O2 permeation source and/or liquid H2O2.standards. Measuring ranges liquid phase:      0 to  30.0  mg/l (free programmable up to 3,000. mg/l.) Measuring ranges gas phase: 0 to  20.0 ppbV (free programmable up to 2.00 ppmV) H2O2 gas phase detection limit of < 50ppt. (Range: 0 to  20.0 ppbV only) H2O2 liquid phase detection limit of < 70 ng/l Rugged and simple to use. RS232- Interface

Instrument Description Principle of operation The detection of peroxides is based on the liquid phase reaction of peroxides with P-Hydroxyphenylacetic Acid catalyzed by Peroxidase. This reaction produces a fluorescent dimer, that can be excited at 326 nm (Cd-lamp) and detected between 400 and 420 nm. The technique is sensitive to all peroxides in the solution. To distinguish between H2O2 and organic peroxides two parallel channels are used. In one channel (channel B) of the instrument, H2O2is destroyed selectively by catalase prior to the fluorescent detection in the instrument. The amount of H2O2is then given by the difference between the signals from the two channels - signal for total peroxide (channel A) minus the signal for total peroxide without H2O2(channel B) - corrected for the destruction efficiency of the catalase solution.                       catalase 2 H2O2      -----> 2 H2O + O2 The above reactions are carried out in aqueous solution of peroxides and other reagents. Therefore, for the measurement of gaseous peroxides, these have to be trapped in aqueous solution first. This is achieved in a stripping coil by pumping air and a stripping solution (pH-Buffered water free of H2O2) continuously at known flow rates. The air and liquid streams are afterwards separated in a glass separator and the solution is then analyzed for peroxides. In the instrument, capable for measuring H2O2 in air and water samples, the H2O2 mixing ratio in air is then calculated from the concentration in solution and the ratio of air and stripping solution flow rates. The coil size and the flow rates of air and stripping solution are optimized for quantitative stripping of H2O2. Due to lower solubilities however, the stripping efficiency for other peroxides is lower than that for H2O2 and probably varies between the 60% found for Methylhydro peroxide and 100% for H2O2. As the composition of organic peroxides in air is unknown, the signal from channel A (after destroying H2O2 by catalase) gives only an approximate estimate of the concentration of organic peroxides. Therefore, the instrument CAN NOT determine exactly the amount of organic peroxides in air but a relative measure of the concentration is indicated. Provided the sensitivity SeA,B is known for each channel, this is the case after performing an calibration cycle, the calculation of concentrations is done in two steps. In the first step the equivalent mixing ratios are calculated from signals from both channels (see  Section 3.). In the second step the H2O2 concentration is calculated from the difference of two equivalent mixing ratios. This difference is then corrected for the transmission efficiency of the inlet tubes, for the catalase destruction efficiency, and for the efficiency of the zero trap. Peroxides in water solutions can be measured directly by each model of the instruments. In this mode, stripping is not necessary and, consequently, either zero air has to be applied to the samples inlet or the internal zero trap has to be switched on. Model AL2021W has been designed for measuring H2O2 only in water samples. Therefore no stripping coil is required. 1.2. Instrument Specifications The measurement range of the instrument can be set within the ranges given below. a) Liquid phase measurements (provides calibration by liquid peroxide standard): (free programmable up to 2,000.0 mg/l. - Measuring range : 0 to  300   mg/l* b) Gas phase measurements (provides calibration by liquid peroxide standard if no gas phase standard is available): (free programmable up to 2,000.0 ppbV - Measuring range :      0 to  100   ppbV * c) Gas phase measurements (provides calibration by gas standard. gas standard permeation rate can be determined by using liquid standard)  Measuring range : 0 to  100.0  ppbV Detection limit: < 50 ppt gas phase (calibration with 30 mg/l or internal H2O2- source) < 0.07 mg/l equivalent to 2 * 10-9 M in solution (liquid phase) Noise (each channel)< 2% at full scale Time constant            100 sec (10-90%), delay time 180 sec Interferences from: O3                   30 ppt H2O2/100  ppb O3 NO                  12 ppt H2O2/100  ppb  NO No detectable interference from:    SO2, PAN, NO2, Glyoxal, Isobutane, Isobutylene, 1-Butane, Formaldehyde, Benzene, Toluene, Methanol, Acetone, Methylamine, Dimethylamine, n-Butane, Cis-2-Butene, Trans-2-Butene, and Ions such as Iodide, Chloride, Nitrate, Bromide, Phosphate, Benzoate Zeroing:              internal zero trap Calibration:         internal H2O2  permeation   device or liquid of H2O2  standards Signal output: Analog:           0-5 Volts FS. calibration sets automatically output to 4.0 Volt of maximum value of chosen range. Digital:           via RS 232 interface Operating Temp.:       -10to 40 degrees C                                     5 to 95% rel. humid. Physical Dim.:            Width 17 cm Length 33 cm Height 21 cm Weight 7.5 Kg Power Requirem.:      120/240VAC,          80 Watts Maint.   Interval:       1Month