Aiming to prove the usefulness of the proposed procedure a set of bleach samples was analyzed.
In this work an automatic photometric procedure for the determination of chlorine in bleach samples employing N,N′-diethyl-p-phenylenediamine (DPD) as chromogenic reagent is described.
Therefore, the optimum sample protocol selected (and applied in all further analyses) was to bleach samples in 12% NaOCl (50 μL/mg of sample) for 48 h, maximising removal of the inter-crystalline proteins but minimising induced racemization.
Table 1 FSDP positions Q of X-ray scattering profiles for amorphous silica (Q is (4pi sin theta /lambda)): λ is wavelength of X-ray) Sample Q (Å−1) Bleached sample 1.59 Silica gel (used in this study) 1.63 Silica gel (Kamiya and Nasu 1998) 1.60 1.70 Silica glass (Shimada et al. 2002) 1.52.
Many applications of luminescence dating to geo-archaeological and environmental systems face the challenges of complex depositional sequences with heterogeneous and incompletely bleached samples.
The optimized method was also successfully validated by the assay of H2O2 in commercial hair bleaching samples and compared to the corresponding values obtained by the reference spectrophotometric method.
In this paper, laboratory bleached samples from both the above studies are remeasured, using an experimental design to correct for OSL sensitivity changes, which has some similarities to the single aliquot regenerative dose (SAR) protocol of Murray and Wintle (Murray A.S., Wintle A.G., 2000.
The two sets of bleached samples (bulked powders and individual granules) were prepared and analysed in separate batches by RP-HPLC and the LOD was calculated for each batch, using the average concentration of amino acids found in procedural blanks: LOD = [average blanks] × 3.
Pairs of neighbouring nubbins were chosen for the post-experimental comparison of T0 and bleached samples based on the assumption that neighbouring nubbins from the same colony do not only share an identical genotype, but were also exposed to a similar micro-climate in the field.
We show that the removal of the extra-crystalline contaminants and matrix protein is the most critical step for reproducible results and recommend a protocol of bleaching samples in NaOCl for 48 h to maximise removal of open system proteins while minimising the induced racemization.
