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MPS Out Tablets

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  1. Product Code: 515930 Lovibond MPS-Out Photometer Tablets
    £19.54 £16.28
  2. Lovibond MPS-Out/Rapid Tablets
    Product Code: 515901 Lovibond MPS-Out/Rapid Tablets
    £31.57 £26.31

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When testing pool water samples (containing monopersulphate) for chlorine, interference to the combined chlorine test is observed. A supplementary procedure using ‘MPS OUT’ tablets allows the determination of both the combined chlorine and the monopersulphate concentrations.

1) The differential determination of free and combined chlorine

a) Carry out the DPD No.1 test in the usual way:- i.e. rinse a clean tube with pool water sample, leaving a few drops at the bottom, crush the tablet with a clean stirring rod then add water to the 10ml. line. Mix well to dissolve and take an immediate reading:- (Reading A = free chlorine ).

b) Add an MPS OUT tablet to the solution from a) above (this removes the monopersulphate, but not the combined chlorine), crush and mix to dissolve then add a DPD No.3 tablet. After mixing again, leave for 2 minutes then record the reading:- (Reading B = total chlorine)

Combined chlorine = Readings( B – A)

2) Determination of monopersulphate

Add one DPD No.4 tablet ( or both a DPD No.1 and a DPD No.3 )to a clean tube moistened with pool water sample and crush the tablets. Add sample to the 10ml. line, mix well to dissolve. Leave for 2 minutes and take the reading:- (Reading C = total chlorine + monopersulphate)

Monopersulphate = Reading (C – B) (expressed as chlorine)

( For concentration as MPS multiply this reading by 5)


1)Free chlorine (DPD No.1) = 0.6mg./l. (Reading A)

Total chlorine (MPS OUT & DPD No.3) = 0.7mg./l. (Reading B)

Combined chlorine (Reading B – A) = 0.1mg./l.

2) Total chlorine & monopersulphate (DPD No1 + DPD No3) =1.8 mg/l. (Reading C)

Monopersulphate concentration = 1.8 – 0.7 = 1.1mg./l. as chlorine.

Actual monopersulphate concentration = 1.1 x 5 = 5.5mg./l.