A pilot study demonstrating the efficacy of transcutaneous bilirubin meters to quantitatively differentiate contusions from Congenital Dermal Melanocytosis.

OBJECTIVE: Congenital Dermal Melanocytosis (CDM) can be difficult to differentiate from contusions. The need for a prompt and accurate diagnosis is best illustrated in cases where child abuse and maltreatment is of concern. Transcutaneous bilirubin (TCB) spectrophotometry has been well established to measure bilirubin under the skin for jaundice in infants. The use of TCB spectrometry has not been used to identify or differentiate contusions from CDM. We hypothesized that bilirubin, a degradation product of hemoglobin, would be elevated in contusions but not in CDM thus demonstrating the efficacy of a novel diagnostic technique to compliment or improve on physical assessment alone. METHODS: Pilot study with thirty-seven infants and children noted to have CDM and fifty-six infants, children and adults with contusions underwent measurement of their lesion with TCB spectrometry. In each patient, the affected skin was scanned along with the adjacent unaffected native skin allowing an internal control for individual pigment variation. RESULTS: TCB measurements of CDM resulted in lower transcutaneous bilirubin values that were not significantly different from adjacent native skin pigmentation. This was in contrast to cutaneous contusions, which resulted in a higher measured value (mean 5.01 mg/dL) compared to adjacent native tissue (1.24 mg/dL) demonstrating a four-fold increase in measurement at the lesion site (P < 0.001). Direct comparison of a ΔTCB value (lesion measurement minus the adjacent tissue) demonstrated a significantly higher value in contusions compared to CDM with a mean value of 3.77 and 0.12 mg/dL, respectively (P < 0.001). CONCLUSIONS: TCB Spectrometry as a novel diagnostic technique has the potential to discern contusions from CDM and may therefore have the ability to compliment the use of physical assessment alone.

Reliability of maximal mitochondrial oxidative phosphorylation in permeabilized fibers from the vastus lateralis employing high-resolution respirometry.

The purpose was to assess the impact of various factors on methodological errors associated with measurement of maximal oxidative phosphorylation (OXPHOS) in human skeletal muscle determined by high-resolution respirometry in saponin-permeabilized fibers. Biopsies were collected from 25 men to assess differences in OXPHOS between two muscle bundles and to assess the correlation between OXPHOS and the wet weight of the muscle bundle. Biopsies from left and right thighs of another five subjects were collected on two occasions to compare limbs and time-points. A single muscle specimen was used to assess effects of the anesthetic carbocaine and the influence of technician. The difference in OXPHOS between two fiber-bundles from the same biopsy exhibited a standard error of measurement (SEM) of 10.5 pmol · s-1  · mg-1 and a coefficient of variation (CV) of 15.2%. The differences between left and right thighs and between two different time-points had SEMs of 9.4 and 15.2 pmol · s-1  · mg-1 and CVs of 23.9% and 33.1%, respectively. The average (±SD) values obtained by two technicians monitoring different bundles of fibers from the same biopsy were 31.3 ± 7.1 and 26.3 ± 8.1 pmol · s-1  · mg-1 . The time that elapsed after collection of the biopsy (up to a least 5 h in preservation medium), wet weight of the bundle (from 0.5 to 4.5 mg) and presence of an anesthetic did not influence OXPHOS. The major source of variation in OXPHOS measurements is the sample preparation. The thigh involved, time-point of collection, size of fiber bundles, and time that elapsed after biopsy had minor or no effect.

Noninvasive Measurement of Hemoglobin Using Spectrophotometry: Is it Useful for the Critically Ill Child?

This study compared the accuracy of noninvasively measuring hemoglobin using spectrophotometry (SpHb) with a pulse CO-oximeter and laboratory hemoglobin (Hb) measurements. A total of 345 critically ill children were included prospectively. Age, sex, and factors influencing the reliabilityof SpHb such as SpO2, heart rate, perfusion index (PI), and vasoactive inotropic score were recorded. SpHb measurements were recorded during the blood draw and compared with the Hb measurement. Thirteen patients (low PI in 9 patients and no available Hb in 4 patients) were excluded and 332 children were eligible for final analysis. The mean Hb was 8.71±1.49 g/dL (range, 5.9 to 12 g/dL) and the mean SpHb level was 9.55±1.53 g/dL (range, 6 to 14.2 g/dL). The SpHb bias was 0.84±0.86,with the limits of agreement ranging from -2.5 to 0.9 g/dL. The difference between Hb and SpHb was >1.5 g/dL for only 47 patients. Of these, 24 patients had laboratory Hb levels <7 g/dL. There was a weak positive correlation between differences and PI (r=0.349; P= 0.032). The pulse CO-oximeter is a promising tool for measuring SpHb and monitoring critically ill children. However, PI may affect these results. Additional studies investigating the reliability of the trend of continuous SpHb values compared with simultaneously measured laboratory Hb values in the same patient are warranted.

Variation in pre-PCR processing of FFPE samples leads to discrepancies in BRAF and EGFR mutation detection: a diagnostic RING trial.

AIMS: Mutation detection accuracy has been described extensively; however, it is surprising that pre-PCR processing of formalin-fixed paraffin-embedded (FFPE) samples has not been systematically assessed in clinical context. We designed a RING trial to (i) investigate pre-PCR variability, (ii) correlate pre-PCR variation with EGFR/BRAF mutation testing accuracy and (iii) investigate causes for observed variation. METHODS: 13 molecular pathology laboratories were recruited. 104 blinded FFPE curls including engineered FFPE curls, cell-negative FFPE curls and control FFPE tissue samples were distributed to participants for pre-PCR processing and mutation detection. Follow-up analysis was performed to assess sample purity, DNA integrity and DNA quantitation. RESULTS: Rate of mutation detection failure was 11.9%. Of these failures, 80% were attributed to pre-PCR error. Significant differences in DNA yields across all samples were seen using analysis of variance (p<0.0001), and yield variation from engineered samples was not significant (p=0.3782). Two laboratories failed DNA extraction from samples that may be attributed to operator error. DNA extraction protocols themselves were not found to contribute significant variation. 10/13 labs reported yields averaging 235.8 ng (95% CI 90.7 to 380.9) from cell-negative samples, which was attributed to issues with spectrophotometry. DNA measurements using Qubit Fluorometry demonstrated a median fivefold overestimation of DNA quantity by Nanodrop Spectrophotometry. DNA integrity and PCR inhibition were factors not found to contribute significant variation. CONCLUSIONS: In this study, we provide evidence demonstrating that variation in pre-PCR steps is prevalent and may detrimentally affect the patient's ability to receive critical therapy. We provide recommendations for preanalytical workflow optimisation that may reduce errors in down-stream sequencing and for next-generation sequencing library generation.

[Method validation according to ISO 15189 and SH GTA 04: application for the extraction of DNA and its quantitative evaluation by a spectrophotometric assay]. / Validation de méthode selon la norme ISO 15189 et le SH GTA 04: application à l'extraction et au dosage quantitatif de l'ADN par méthode spectrophotométrique.

According to the French legislation on medical biology (January 16th, 2010), all biological laboratories must be accredited according to ISO 15189 for at least 50% of their activities before the end of 2016. The extraction of DNA from a sample of interest, whether solid or liquid is one of the critical steps in molecular biology and specifically in somatic or constitutional genetic. The extracted DNA must meet a number of criteria such quality and also be in sufficient concentration to allow molecular biology assays such as the detection of somatic mutations. This paper describes the validation of the extraction and purification of DNA using chromatographic column extraction and quantitative determination by spectrophotometric assay, according to ISO 15189 and the accreditation technical guide in Human Health SH-GTA-04.

Methods for detection of oxidative stress and genotoxicity of engineered nanoparticles.

The distinctive characteristics of engineered nanoparticles (ENPs) such as higher surface-to-volume ratio find immense applications in personal care products, food packaging, drug delivery systems, therapeutics & biosensors and others. The exponential increase in the ENP containing consumer products in the last 5 years has also increased their inadvertent release in the environment and a debate towards their adverse effects to the human and environment health. A variety of ENPs with different size, shape, and surface properties have been shown to induce genotoxicity, cytotoxicity, and oxidative stress in different cellular models. Here we describe the techniques and protocols used in the assessment of the genotoxicity (single-cell gel electrophoresis (comet) assay, cytokinesis block micronucleus assay) and oxidative stress parameters (reactive oxygen species, lipid peroxidation, and glutathione depletion) induced by the ENPs in the cells.

Systematic comparisons of various spectrophotometric and colorimetric methods to measure concentrations of protein, peptide and amino acid: detectable limits, linear dynamic ranges, interferences, practicality and unit costs.

There is limited and inconclusive information regarding detectable limits and linear dynamic ranges of various quantitative protein assays. We thus performed systematic comparisons of seven commonly used methods, including direct spectrophotometric quantitation at λ205 and λ280 nm (A205 and A280, respectively), bicinchoninic acid (BCA), Biuret, Bradford, Lowry and Ninhydrin methods. Purified BSA, porcine kidney extract, tryptic digested peptides derived from purified BSA, and glycine, were used as representative purified protein, complex protein mixture, peptide and amino acid, respectively. Bradford method was the most sensitive assay (LOD=0.006 mg/ml) and had the widest range of detectability (LOD-UOD=0.006-100mg/ml) for purified protein and complex protein mixture. For peptide, A205, A280, Lowry and Ninhydrin methods had a comparable LOD (0.006 mg/ml), but Ninhydrin method had the widest detectability range (LOD-UOD=0.006-100mg/ml). For amino acid, A205 and Ninhydrin methods had a comparable LOD (0.006 mg/ml), but A205 had a wider detectability range (LOD-UOD=0.006-6.250 mg/ml). Biuret method offered the widest linear dynamic range for purified protein and complex protein mixture (0.391-100mg/ml), A280 offered the widest linear dynamic range for peptide (0.024-6.250 mg/ml), and Ninhydrin method offered the widest linear dynamic range for amino acid (0.024-0.195 mg/ml). Both Laemmli's and 2-D lysis buffers had dramatic interfering effects on all assays. Concerning the practicality and unit costs, A205 and A280 were the most favorable. Among the colorimetric methods, Bradford method consumed the least amount of samples and shortest analytical time with the lowest unit cost. These are the most extensive comparative data of commonly used quantitative protein assays that will be useful for selecting the most suitable method for each study.

Protein thiolation index (PTI) as a biomarker of oxidative stress.

Several biomarkers of oxidative stress have been proposed and used in clinical research but so far unreliable or, at least, controversial results have been obtained. Given the high susceptibility of sulfhydryl groups to oxidation, we here suggest the use of a protein thiolation index (PTI), i.e., the molar ratio between the sum of all low molecular mass thiols bound to plasma proteins (forming, as a whole, S-thiolated proteins) and protein free cysteinyl residues, as a suitable biomarker of oxidative stress. While titration of free thiols can be performed by a simple spectrophotometric procedure, accurate quantification of S-thiolated proteins is problematic and current methods require, in most cases, application of time-consuming chromatographic techniques, making their application to large-scale clinical studies difficult. Here we report a new spectrophotometric method which relies on the specific determination of low molecular mass thiols released from S-thiolated proteins after dithiothreitol reduction. These amino acids can be titrated by conjugation with ninhydrin which, reacting with primary and secondary amine groups, yields a deep blue-purple color, which can be spectrophotometrically revealed. PTI showed an age dependency with a near linear increase during aging in humans. In addition, PTI was significantly higher in patients suffering from alkaptonuria with respect to healthy controls, suggesting that increased prooxidant conditions occur in the blood of these subjects.

A comparison of three methods of hemoglobin monitoring in patients undergoing spine surgery.

BACKGROUND: Hemoglobin values (Hb) can facilitate decisions regarding perioperative transfusion management. Currently, Hb can be determined invasively by analyzing blood via laboratory Co-Oximetry (tHb) or by point-of-care HemoCue (HCue). Recently, a new noninvasive, continuous spectrophotometric sensor (Masimo SpHb) was introduced into clinical practice. We compared the accuracy of the SpHb and HCue with tHb. METHODS: Twenty patients, ages 40 to 80 years, were studied. They received general anesthesia and underwent spine surgery in the prone position. All blood samples were obtained from a radial artery catheter. SpHb, tHb, and HCue were determined immediately after induction of anesthesia, but before the start of surgery and approximately every hour thereafter. Primary outcomes were defined on the basis of the following differences between measures: SpHb - tHb or HCue - tHb. All patients had 3 to 5 observations taken on each measure. Differences and absolute differences were analyzed by several techniques to assess accuracy. We also investigated the relationship between observed differences and the following variables: tHb level, duration of surgery, age, weight, and perfusion index. RESULTS: Data consisted of 78 measurements of SpHb, tHb, and HCue made on the 20 patients. Absolute differences between SpHb and tHb were <1.5 g/dL for 61% of observations, between 1.6 to 2.0 g/dL for 16% and >2.0 g/dL for 22% of the observations. Observed differences displayed significant decreases with time and higher perfusion index values. No systematic relationships were observed with age or weight. Except for 1 value, all of the HCue values were <1.0 g/dL of tHb. CONCLUSIONS: Although HCue was consistently accurate, our data confirm that SpHb often correlated well with tHb values. Yet our study indicates that SpHb may not be as accurate as clinically necessary in some patients. Improved refinement of continuous, noninvasive technology, such as SpHb, could address important clinical requirements.

The role of spectrophotometry in the diagnosis of melanoma.

BACKGROUND: Spectrophotometry (SPT) could represent a promising technique for the diagnosis of cutaneous melanoma (CM) at earlier stages of the disease. Starting from our experience, we further assessed the role of SPT in CM early detection. METHODS: During a health campaign for malignant melanoma at National Cancer Institute of Naples, we identified a subset of 54 lesions to be addressed to surgical excision and histological examination. Before surgery, all patients were investigated by clinical and epiluminescence microscopy (ELM) screenings; selected lesions underwent spectrophotometer analysis. For SPT, we used a video spectrophotometer imaging system (Spectroshade MHT S.p.A., Verona, Italy). RESULTS: Among the 54 patients harbouring cutaneous pigmented lesions, we performed comparison between results from the SPT screening and the histological diagnoses as well as evaluation of both sensitivity and specificity in detecting CM using either SPT or conventional approaches. For all pigmented lesions, agreement between histology and SPT classification was 57.4%. The sensitivity and specificity of SPT in detecting melanoma were 66.6% and 76.2%, respectively. CONCLUSIONS: Although SPT is still considered as a valuable diagnostic tool for CM, its low accuracy, sensitivity, and specificity represent the main hamper for the introduction of such a methodology in clinical practice. Dermoscopy remains the best diagnostic tool for the preoperative diagnosis of pigmented skin lesions.

Effects of buflomedil and pentoxifylline on hamster skin-flap microcirculation: prediction of flap viability using orthogonal polarization spectral imaging.

OBJECTIVE: This study investigated the effects of buflomedil and pentoxifylline, both of which are used in reconstructive surgery of hamster skin flap microcirculation, and evaluated the skin flap survival rate by orthogonal polarization spectral imaging. METHOD: Twenty-four adult male Syrian golden hamsters were divided into three groups: a control (C, 0.1 ml 0.9% saline), buflomedil (B, 3 mg/kg/day), and pentoxifylline group (P, 14.5 mg/kg/day). Treatments administered intraperitoneally were initiated 1 hour before skin flap preparation and continued for 7 days post-operatively at 12-hour intervals. Preparations (skin flaps) were divided into 12 fields, which were organized into six bands. Functional capillary density (FCD, in mm/mm(2)), distance from the skin flap base to blood flow cessation (Dist(with flow), in cm), percentage of viable skin (VA, in%), and qualitative analysis of blood flow by orthogonal polarization spectral imaging were performed at 1 and 24 hours and on the seventh post-operative day. RESULT: Bands IV, V, and VI presented no flow independent of time. The functional capillary density group B was higher than that of groups C and P, primarily after 24 hours. All groups showed an increase in D with time but reached similar final distances (C = 2.73, B = 2.78 and P = 2.70 cm). Moreover, the percentage of viable areas remained at approximately 50%. The orthogonal polarization spectral imaging was useful to assess viability by counting fields with and without blood flow. CONCLUSIONS: Functional capillary density values were higher in the buflomedil group compared to the control and pentoxifylline groups in this model. Functional capillary density did not influence D or the percentage of VA, and the technique showed favorable potential to assess/predict the viability of skin flaps within 1 h after surgery.

Indocyanine green clearance test and model for end-stage liver disease score of patients with liver cirrhosis.

BACKGROUND: The indocyanine green (ICG) clearance test (clearance rate (K) and retention rate at 15 minutes (R15)) is a sensitive indicator to evaluate liver function. The model for end-stage liver disease (MELD) score has emerged as a useful tool for estimating the mortality of patients awaiting liver transplantation and has recently been validated on patients with liver diseases of various etiologies and severity. In this study, we investigated the correlation between the ICG clearance test and MELD score of patients with liver cirrhosis. METHODS: From June 2007 to March 2008, 52 patients with liver cirrhosis admitted to our center were classified into Child-Pugh class A (8 patients), B (14) and C (30). The ICG clearance test (K value and R15) was performed by ICG pulse spectrophotometry (DDG-3300K), and the MELD scores of patients were calculated. RESULTS: As the Child-Pugh classification of liver function gradually deteriorated, the K value decreased, while R15 and MELD score increased. There were significant statistical differences in K value, R15 and MELD score in patients with different Child-Pugh classifications. Significant correlations were found between the parameters of the ICG clearance test (K value and R15) and MELD score. A negative correlation was observed between K value and MELD score (r=-0.892, P<0.05), while a positive correlation was observed between R15 and MELD score (r=0.804, P<0.05). CONCLUSIONS: The ICG clearance test and MELD score are good parameters for evaluating liver function. Moreover, K value and R15 have significant correlations with MELD score, especially the K value, which may be a convenient and appropriate indicator to evaluate liver function of patients with liver cirrhosis.

Effects of buflomedil and pentoxifylline on hamster skin-flap microcirculation: prediction of flap viability using orthogonal polarization spectral imaging

OBJECTIVE: This study investigated the effects of buflomedil and pentoxifylline, both of which are used in reconstructive surgery of hamster skin flap microcirculation, and evaluated the skin flap survival rate by orthogonal polarization spectral imaging. METHOD: Twenty-four adult male Syrian golden hamsters were divided into three groups: a control (C, 0.1 ml 0.9 percent saline), buflomedil (B, 3 mg/kg/day), and pentoxifylline group (P, 14.5 mg/kg/day). Treatments administered intraperitoneally were initiated 1 hour before skin flap preparation and continued for 7 days post-operatively at 12-hour intervals. Preparations (skin flaps) were divided into 12 fields, which were organized into six bands. Functional capillary density (FCD, in mm/mm²), distance from the skin flap base to blood flow cessation (Dist with flow, in cm), percentage of viable skin (VA, in percent), and qualitative analysis of blood flow by orthogonal polarization spectral imaging were performed at 1 and 24 hours and on the seventh post-operative day. RESULT: Bands IV, V, and VI presented no flow independent of time. The functional capillary density group B was higher than that of groups C and P, primarily after 24 hours. All groups showed an increase in D with time but reached similar final distances (C = 2.73, B = 2.78 and P = 2.70 cm). Moreover, the percentage of viable areas remained at approximately 50 percent. The orthogonal polarization spectral imaging was useful to assess viability by counting fields with and without blood flow. CONCLUSIONS: Functional capillary density values were higher in the buflomedil group compared to the control and pentoxifylline groups in this model. Functional capillary density did not influence D or the percentage of VA, and the technique showed favorable potential to assess/predict the viability of skin flaps within 1 h after surgery.

Simultaneous determination of nickel and copper by H-point standard addition method-first-order derivative spectrophotometry in plant samples after separation and preconcentration on modified natural clinoptilolite as a new sorbent.

For the simultaneous determination of nickel(ll) and copper(ll) in plant samples, a rapid and accurate method was developed. In this method, solid-phase extraction (SPE) and first-order derivative spectrophotometry (FDS) are combined, and the result is coupled with the H-point standard addition method (HPSAM). Compared with normal spectrophotometry, derivative spectrophotometry offers the advantages of increased selectivity and sensitivity. As there is no need for carrying out any pretreatment of the sample, the spectrophotometry method is easy, but because of a high detection limit, it is not so practical. In order to decrease the detection limit, it is suggested to combine spectrophotometry with a preconcentration method such as SPE. In the present work, after separation and preconcentration of Ni(ll) and Cu(ll) on modified clinoptilolite zeolite that is loaded with 2-[1-(2-hydroxy-5-sulforphenyl)-3-phenyl-5-formaza-no]-benzoic acid monosodium salt (zincon) as a selective chromogenic reagent, FDS-HPSAM, which is a simple and selective spectrophotometric method, has been applied for simultaneous determination of these ions. With optimum conditions, the detection limit in original solutions is 0.7 and 0.5 ng/mL, respectively, for nickel and copper. The linear concentration ranges in the proposed method for nickel and copper ions in original solutions are 1.1 to 3.0 x 10(3) and 0.9 to 2.0 x 10(3) ng/mL, respectively. The recommended procedure is applied to successful determination of Cu(ll) and Ni(ll) in standard and real samples.

Spectrophotometric determination of urea in sugar cane distilled spirits.

Urea is an important precursor in the formation of ethyl carbamate, a known carcinogen in alcoholic beverages. Ethyl carbamate has recently been detected at high concentrations in sugar cane distilled spirits, but little is known about the concentration of urea in these beverages. The objectives of this study were to validate methodology for the determination of urea in sugar cane distilled spirits, to determine the levels in 68 samples from different regions within the state of Minas Gerais, Brazil, and to examine the relationship between the concentrations of urea and ethyl carbamate. The method, based on the reaction of urea with 1-phenyl-1,2-propanodione-2-oxime and spectrophotometric quantification at 540 nm, provided linear response from 0.5 to 15.0 mg/L. No purification of the sample was required. The limits of detection and quantification were 0.1 and 0.5 mg/L, respectively. Urea was detected in 69% of the samples at levels varying from 0.50 to 5.10 mg/L. There was no significant difference on the levels of urea in samples from different regions of the state. No significant correlation between the levels of urea and ethyl carbamate was observed for the samples analyzed.

Determination of total and oxidized glutathione in human whole blood with a sequential injection analysis system.

This work reports the development of a simple, robust, automated sequential injection analysis (SIA) system for the enzymatic determination of total (tGSH) and oxidized (GSSG) glutathione in human whole blood. The reduced (GSH) glutathione concentration is then obtained as the difference between the tGSH and GSSG concentrations. The determination was based on the DTNB-GSSG reductase recycling assay, which couples the specificity of the GSSG reductase (GR) with an amplification of the response to glutathione, followed by spectrophotometric detection of the 2-nitro-5-thiobenzoic acid (TNB) formed (lambda=412 nm). The implementation of this reaction in a SIA flow system with an in-line dilution strategy permitted the necessary distinct application ranges for tGSH and for GSSG. It also guaranteed the exact timing of fluidic manipulations and precise control of the reaction conditions. The influence of parameters such as reagents concentration, temperature, pH, flow rate of the carrier buffer solution, as well as reaction coil length, etc., on the sensitivity and performance of the SIA system were studied and the optimum reaction conditions subsequently selected. Linear calibration plots were obtained for GSH and GSSG concentrations up to 3.00 and 1.50 microM, with detection limits of 0.031 and 0.014 microM, respectively. The developed methodology showed good precision, with a relative standard deviation (R.S.D.)<5.0% (n=10) for determination of both glutathione forms. Statistical evaluation showed good compliance, for a 95% confidence level, between the results obtained with the SIA system and those furnished by the comparison batch procedure.

Spectrophotometric determination of plutonium in highly radioactive liquid waste using an internal standardization technique with neodymium(III).

A simple and rapid spectrophotometric method has been developed for the determination of Pu in highly radioactive liquid waste. This method uses Nd(III) as an internal standard, which enables us to determine the concentration of Pu and to authenticate the whole analytical scheme as well. A Nd(III) standard mixed with a sample solution and Pu was quantitatively oxidized to Pu(VI) with Ce(IV) in a nitric acid medium, having the maximum absorbance at 830 nm. A spectrophotometric measurement of Pu(VI) was subsequently performed to determine the concentration compared with the maximum absorbance of Nd(III) at 795 nm. It was estimated that the relative expanded uncertainty for a real sample is less than 10%. The limit of detection was calculated to be 1.8 mg/L (3 sigma). The proposed method was also validated through comparison experiments with isotope dilution mass spectrometry, and was successfully applied to analysis for nuclear waste management at spent nuclear fuel reprocessing plants.

Simultaneous spectrophotometric determination of cobalt and nickel by partial least square regression in micellar media.

Diphenycarbazone has been used for the simultaneous determination of cobalt and nickel by partial least square regression method. DPC complexes of cobalt and nickel at pH 7-10 are of pink color, which are soluble in TX-100 micellar media. A partial least square multivariate calibration method for the analysis of binary mixtures of cobalt and nickel was developed. The total relative standard error for applying the PLS method was calculated. The accuracy and reproducibility of the determination method for various known amounts of Co(II) and Ni(II) in their binary mixtures were tested. The effects of diverse ions on the determination of cobalt and nickel to investigate the selectivity of the method were also studied. The proposed method was applied to the synthetic binary mixtures, alloys and pharmaceutical samples.

Optical devices used for image analysis of pigmented skin lesions: a proposal for quality assurance protocol using tissue-like phantoms.

Different technological tools have been developed to aid in the diagnosis of pigmented skin lesions, including cameras working with conventional RGB colour systems, epiluminescence microscopy and spectrophotometric methods using visible and near infrared wavelengths. All the different procedures should provide in an objective and reproducible fashion quantitative measurements of the colour and shape features of a given skin mole. At present, many devices have been introduced in experimental stages for clinical diagnosis, mainly used to provide to the clinicians an objective, computer-assisted second opinion. As for any diagnostic instruments, optical devices should also be subjected to a dedicated quality assurance protocol in order to evaluate the response repeatability of each device (intra-instrument agreement) and to check the accordance among the responses of different devices (inter-instrument agreement). The aim of this study was to design a quality assurance protocol for optical devices dedicated to image analysis of pigmented skin lesions and, in case, to detect cutaneous melanoma by using suitable tissue-like phantoms as standard references that enable testing of both hardware and software components. As an example, we report the results of intra-instrument and inter-instrument agreement when the protocol was applied on a series of 30 SpectroShade instruments, a novel optical device based on multi-spectral image analysis of colour and shape features of pigmented skin lesion.