UV/VIS Analysis of Sodium Hypochlorite (Generic Ultra Bleach)
Goal:
Determine the detection limits for chlorine in bleach
Method:
Absorbance
Introduction:
Feasibility testing was done to assess the detection of bleach with OOI hardware and to determine the optimal hardware configuration for detecting 10, 20 and 30 ppm sodium hypochlorite.
Attempts to measure chlorine with another system (USB2000 (USB2E3017) with grating #2, 25 um slit, UV2 detector upgrade, OFLV order sorting filter and L2 detector collection lens, DT1000-S source, CUV-UV cuvette holder, 400 um SR fiber on one leg, 200 um UV/VIS fiber on the other leg, CVD-UV1S cuvette were not successful at the 30 ppm sodium hypochlorite level.
Hardware Used:
USB2000 (USB2E214) with grating #1, 50 um slit, L2 detector collection lens and OFLV order sorting filter
CUV-UV cuvette holder
P400-025-UV-SR optical fibers
DT1000 deuterium tungsten halogen
Acquisition Parameters:
Integration Time (msec): 7
Spectra Averaged: 100
Boxcar Smoothing: 3
Measurement Mode:
Absorbance
Experimental Conditions:
Generic ultra bleach for household use was diluted with water to provide sodium hypochlorite samples. According to information on the internet, ultra bleach is 6% sodium hypochlorite or 60,000 ppm. Water was used to dilute the 6% solution down to 10, 20 and 30 ppm.
Results:
The plot below contains spectral data for 10, 20 and 30 ppm sodium hypochlorite. A peak at 295 nm is observed. This peak intensity decreases with dilution of the sodium hypochlorite.
Conclusions:
The use of a larger slit and UV optimized grating in the spectrometer (50 um slit versus 25 um and grating 1 versus grating 2) resulted in excellent detection of 10 to 30 ppm sodium hypochlorite. These concentrations are easily detectable with OOI hardware.
Tags: absorbance, bleach, chlorine
