Electro‐driven extraction of inorganic anions from water samples and water miscible organic solvents and analysis by ion chromatography

A simple electromembrane extraction (EME) procedure combined with ion chromatography (IC) was developed to quantify inorganic anions in different pure water samples and water miscible organic solvents. The parameters affecting extraction performance, such as supported liquid membrane (SLM) solvent, extraction time, pH of donor and acceptor solutions, and extraction voltage were optimized. The optimized EME conditions were as follows: 1‐heptanol was used as the SLM solvent, the extraction time was 10 min, pHs of the acceptor and donor solutions were 10 and 7, respectively, and the extraction voltage was 15 V. The mobile phase used for IC was a combination of 1.8 mM sodium carbonate and 1.7 mM sodium bicarbonate. Under these optimized conditions, all anions had enrichment factors ranging from 67 to 117 with RSDs between 7.3 and 13.5% (n = 5). Good linearity values ranging from 2 to 1200 ng/mL with coefficients of determination (R²) between 0.987 and 0.999 were obtained. The LODs of the EME‐IC method ranged from 0.6 to 7.5 ng/mL. The developed method was applied to different samples to evaluate the feasibility of the method for real applications.     

An electromembrane extraction–HPLC‐UV analysis for the determination of valproic acid in human plasma

In this study, an electromembrane extraction (EME) method combined with a simple HPLC‐UV analysis was developed and validated for the determination of valproic acid in human plasma samples. The major parameters influencing EME procedure, namely the solvent composition, voltage, pH of acceptor and donor solutions, salt effect, and time of extraction, were evaluated and optimized. The drug was extracted from the donor aqueous sample solution (pH 5) to the acceptor aqueous solution (pH 13). The donor and acceptor phases were separated by a hollow fiber dipped in 1‐octanol as a supported liquid membrane. A voltage of 60 V during 25 min was applied as the driving force. The drug concentration enrichment factor obtained was >125, which enhanced the sensitivity of the method. The limit of detection and the limit of quantitation were 0.2 and 0.5 μg/mL, respectively. The proposed method was successfully applied to a human plasma sample, with a relative recovery of 75%. The method was linear over the range 0.5–10 μg/mL for valproic acid (R² > 0.9996) with a repeatability (%RSD) between 0.9 and 3.3% (n = 3). Valproic acid is an anticonvulsant drug with poor UV absorption, and EME can improve the sensitivity of HPLC‐UV for the determination of valproic acid in plasma samples.     

Electromembrane extraction combined with gas chromatography for quantification of tricyclic antidepressants in human body fluids

Recent advances in electromembrane extraction (EME) methodology calls for effective and accessible detection methods. Using imipramine and clomipramine as model therapeutics, this proof-of-principle work combines EME with gas chromatography analysis employing a flame ionization detector (FID). The drugs were extracted from acidic aqueous sample solutions, through a supported liquid membrane (SLM) consisting of 2-nitrophenyl octyl ether (NPOE) impregnated on the walls of the hollow fiber. EME parameters, such as SLM composition, type of ion carrier, pH and the composition of donor and acceptor solutions, agitation speed, extraction voltage, and extraction time were studied in detail. Under optimized conditions, the therapeutics were effectively extracted from different matrices with recoveries ranging from 90 to 95%. The samples were preconcentrated 270–280 times prior to GC analysis. Reliable linearity was also achieved for calibration curves with a regression coefficient of at least 0.995. Detection limits and intra-day precision (n = 3) were less than 0.7 ng mL⁻¹ and 8.5%, respectively. Finally, method was applied to determination and quantification of drugs in human plasma and urine samples and satisfactory results were achieved.     

Quantitative aspects of electrolysis in electromembrane extractions of acidic and basic analytes

Electrolysis is omnipresent in all electrochemical processes including electromembrane extraction (EME). The effects of electrolysis on quantitative aspects of EME were comprehensively evaluated for a set of acidic (substituted phenols) and basic (basic drugs) analytes. EMEs were carried out across supported liquid membranes formed by 1-ethyl-2-nitrobenzene at standard EME conditions, i.e., acidic analytes were extracted from alkaline into alkaline solutions and basic analytes were extracted from acidic into acidic solutions. Electric potential applied across the EME systems was 50 V and extraction recoveries of analytes as well as pH values of donor and acceptor solutions were determined after each EME. It has been proven that electrolysis plays a more significant role than has ever been thought before in EME. Electrolytically produced H⁺ and OH^– ions had a significant effect on pH values of acceptor solutions and variations of up to 8.5 pH units were obtained at standard EME conditions. pH values of donor solutions were affected only negligibly due to their significantly higher volumes. The observed variations in pH values of acceptor solutions had fatal consequences on quantitative EME results of weak and medium strong acidic/basic analytes. A direct relation was observed between the decrease in extraction recoveries of the analytes, their pK_a values and the acceptor solution pH values. Acceptor solutions consisting of high concentrations of weak bases or acids were thus proposed as suitable EME operational solutions since they efficiently eliminated the electrolytically induced pH variations, offered stable EME performances and were easily compatible with subsequent analytical methods.     

Graphene oxide assisted electromembrane extraction with gas chromatography for the determination of methamphetamine as a model analyte in hair and urine samples

In the present study, graphene oxide reinforced two‐phase electromembrane extraction (EME) coupled with gas chromatography was applied for the determination of methamphetamine as a model analyte in biological samples. The presence of graphene oxide in the hollow fiber wall can increase the effective surface area, interactions with analyte and polarity of support liquid membrane that leads to an enhancement in the analyte migration. To investigate the influence of the presence of graphene oxide in the support liquid membrane on the extraction efficiency, a comparative study was performed between graphene oxide and graphene oxide/EME methods. The extraction parameters such as type of organic solvent, pH of the donor phase, stirring speed, time, voltage, salt addition and the concentration of graphene oxide were optimized. Under the optimum conditions, the proposed microextraction technique provided low limit of detection (2.4 ng/mL), high preconcentration factor (195–198) and high relative recovery (95–98.5%). Finally, the method was successfully employed for the determination of methamphetamine in urine and hair samples.     

Two‐phase electromembrane extraction followed by gas chromatography‐mass spectrometry analysis

A two‐phase electromembrane extraction (EME) was developed and directly coupled with gas chromatography mass spectrometry (GC‐MS) analysis. The proposed method was successfully applied to the simultaneous determination of imipramine, desipramine, citalopram and sertraline. The model compounds were extracted from neutral aqueous sample solutions into the organic phase filled in the lumen of the hollow fiber. This method was accomplished with 1‐heptanol as organic phase, by means of 60 V applied voltage and with the extraction time of 15 min. Experiments reported recoveries in the range of 69–87% from 1.2 mL neutral sample solution. The compounds were quantified by GC‐MS instrument, with acceptable linearity ranging from 1 to 500 ng mL^?1 (R² in the range of 0.989 to 0.998), and repeatability (RSD) ranging between 7.5 and 11.5% (n = 5). The estimated detection limits (S/N ratio of 3:1) were less than 0.25 ng mL^?1. This novel approach based on two‐phase EME brought advantages such as simplicity, low‐costing, low detection limit and fast extraction with a total analysis time less than 25 min. These experimental findings were highly interesting and demonstrated the possibility of solving ionic species in the organic phase at the presence of electrical potential.     

Determination of thebaine in water samples, biological fluids, poppy capsule, and narcotic drugs, using electromembrane extraction followed by high-performance liquid chromatography analysis

Opium determination is of great importance from toxicological and pharmaceutical standpoints. In present work, electromembrane extraction (EME) coupled with high-performance liquid chromatography (HPLC) and ultraviolet (UV) detection was developed for determination of thebaine as a natural alkaloid, in different matrices containing water, urine, poppy capsule, street heroine, and codeine tablet. Thebaine migrated from 3 mL of sample solutions, through a thin layer of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of a porous hollow fiber, and into a 15 μL acidic aqueous acceptor solution present inside the lumen of the fiber. The variables of interest, such as chemical composition of the organic liquid membrane, stirring speed, extraction time and voltage, pH of donor and acceptor phases and salt effect in the EME process were optimized. Under optimal conditions, thebaine was effectively extracted from different matrices with recoveries in the range of 45–55%, which corresponded to preconcentration factors in the range of 90–110. Good linearity was achieved for calibration curves with a coefficient of estimation higher than 0.997. Detection limits and intra-day precision (n = 3) were less than 15 μg L⁻¹ and 8.9%, respectively.     

Comparison of the performance of pyridine-functionalized nanoporous silica particles for the extraction of gold(III) from natural samples

We have developed a technique for the solid-phase extraction of gold using various kinds of pyridine-functionalized nanoporous silica prior to its determination in various samples using FAAS. The effects of solution pH, sample and eluent flow rate, sample volume and of potentially interfering ions are compared. The limits of detections vary from 28 to 53?pg?mL^?1. The accuracy and precision are between 99.8% and 98.3?% and 0.7 to 1.6?% (RSD), respectively. The method was successfully applied to several standard reference materials.

Glass Stability and Glass Forming Ability of Ge25−xSe75Sbx (x = 12, 15, and 18) Chalcogenide Glasses Using Thermal Parameters

In the present communication glass stability (GS) and glass forming ability (GFA) of Ge_25−xSe₇₅Sb_x (x = 12, 15, and 18) chalcogenide glasses have been calculated in terms of certain thermal parameters, i.e., reduced glass transition temperature (T_rg), Hruby number (H), S-parameter (S), and ΔT. The glassy samples have been prepared by quenching of melt technique. For structure characterization, XRD technique has been used. For thermal analysis Differential Scanning Calorimetery (DSC) has been used. DSC scans have been recorded at different heating rates, i.e., 5, 10, 15, and 20 K min⁻¹. Stability of glassy samples has also been confirmed in terms of activation energy of glass transition calculated by Kissinger relation. All these parameters indicate that GS and GFA both decrease with increase of Sb content in Ge_25−xSe₇₅Sb_x (x = 12, 15, and 18) glassy series.     

Determination of Gold by Flame Atomic Absorption Spectrometry with Hollow Fiber Liquid Phase Microextraction Using Room Temperature Ionic Liquids

A novel method to preconcentrate gold was developed employing a synergistic enhancement of a room temperature ionic liquid combined with hollow fiber liquid phase micro-extraction with flame atomic absorption spectrometry detection. The method is based on the complexation of gold with dithizone. The formed hydrophobic complex was subsequently extracted into the lumen of a hollow fiber. The organic phase was siphoned into FAAS for the determination. A room temperature ionic liquid and dithizone were used the enhancement reagent and chelating reagent, respectively. The addition of a room temperature ionic liquid led to a five-fold improvement in the extraction of gold. The 1-octanol was immobilized in the pores of the polypropylene hollow fiber as the liquid membrane and was also used as the acceptor solution. Some parameters that influenced extraction and determination were evaluated in detail, such as concentrations of the ionic liquid and dithizone, pH of samples, stirring rates, extraction time, and interferences. Under optimized conditions, a detection limit of 0.9 ng mL^?1 and an enrichment factor of 130 were achieved. The relative standard deviation (RSD) was 3.7% for Au (40 ng mL^?1, n = 5). The proposed method was successfully applied to the determination of gold in certified reference environmental samples and ore samples with satisfactory results.     

Scope of partial least‐squares regression applied to the enantiomeric composition determination of ketoprofen from strongly overlapped chromatographic profiles

Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst needs to measure the chiral purity, i.e., when one of the enantiomers is present in the sample in very low concentrations. In this report, we explore the scope of a multivariate chemometric technique based on unfolded partial least‐squares regression, as a mathematical tool to solve this quite frequent difficulty. This technique was applied to obtain quantitative results from partially overlapped chromatographic profiles of R‐ and S‐ketoprofen, with different values of enantioresolution factors (from 0.81 down to less than 0.2 resolution units), and also at several different S:R enantiomeric ratios. Enantiomeric purity below 1% was determined with excellent precision even from almost completely overlapped signals. All these assays were tested on the most demanding condition, i.e., when the minor peak elutes immediately after the main peak. The results were validated using univariate calibration of completely resolved profiles and the method applied to the determination of enantiomeric purity of commercial pharmaceuticals.     

Electromembrane extraction of heavy metal cations followed by capillary electrophoresis with capacitively coupled contactless conductivity detection

Electromembrane extraction (EME) was used as an off-line sample pre-treatment method for the determination of heavy metal cations in aqueous samples using CE with capacitively coupled contactless conductivity detection (CE-C(4) D). A short segment of porous polypropylene hollow fibre was penetrated with 1-octanol and 0.5%?v/v bis(2-ethylhexyl)phosphonic acid and constituted a low cost, single use, disposable supported liquid membrane, which selectively transported and pre-concentrated heavy metal cations into the fibre lumen filled with 100?mM acetic acid acceptor solution. Donor solutions were standard solutions and real samples dissolved in deionized water at neutral pH. At optimized EME conditions (penetration time, 5?s; applied voltage, 75?V; and stirring rate, 750?rpm), 15-42% recoveries of heavy metal cations were achieved for a 5?min extraction time. Repeatability of the EME pre-treatment was examined for six independent EME runs and ranged from 6.6 to 11.1%. Limits of detection for the EME-CE-C(4) D method ranged from 25 to 200?nM, resulting into one to two orders of magnitude improvement compared with CE-C(4) D without sample treatment. The developed EME sample pre-treatment procedure was applied to the analysis of heavy metal cations in tap water and powdered milk samples. Zinc in the real samples was identified and quantified in a background electrolyte solution consisting of 20?mM L-histidine and 30?mM acetic acid at pH 4.95 in about 3?min.     

Electromembrane extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection: Multi‐extraction capabilities to analyses trace metals from saline samples

Simultaneous electromembrane extraction (EME) of six trace metal cations (Cu²⁺, Zn²⁺, Co²⁺, Ni²⁺, Pb²⁺, Cd²⁺) from saline samples was investigated. CE with capacitively coupled contactless conductivity detection (C⁴D) was used to determine the metals in acceptor solutions due to its excellent compatibility with the minute volumes of acceptor solutions. Bis(2‐ethylhexyl)phosphate (DEHPA) was selected as a suitable nonselective modifier for EME transport of target metal cations. Both, the individual effect of each major inorganic cation (Na⁺, K⁺, Ca²⁺, Mg²⁺) and their synergistic effect on EME of the trace metal cations were evaluated. In both cases, a decrease in extraction efficiency was observed when major inorganic cations were present in the sample. This effect was more significant for Ca²⁺ and Mg²⁺. The system was optimized for simultaneous extractions of the six target metals from saline samples (50 mM Na⁺, 5 mM Mg²⁺, 1 mM K⁺, and 1 mM Ca²⁺) and following EME conditions were applied. Organic phase consisted of 1‐nonanol containing 1% (v/v) DEHPA, acceptor solution was 1 M acetic acid (HAc) and sample pH was adjusted to 5. Sample was stirred at 750 rpm and EMEs were carried out at extraction potential of 10 V for 20 min. The method presented a repeatability between 8 and 21.8% (n = 5), good linearity in 0.5–10 μM concentration range (R² = 0.987‐0.999) and LOD better than 2.6 nM. Applicability of the EME–CE–C⁴D method to the analyses of metal cations in drinking water, seawater, and urine samples was also demonstrated.     

One-way and two-way pulsed electromembrane extraction for trace analysis of amino acids in foods and biological samples

In the present work, pulsed electromembrane extraction (PEME) was performed for the first time, as a new concept of electrically enhanced microextraction method, for extraction and quantification of histidine, phenylalanine and tryptophan in different matrices. PEME offers an alternative to conventional electromembrane extraction (EME), which faces problems such as serious instabilities in the analysis of real samples with high concentration levels of ions. In these samples, increasing of the ion transportation across the liquid membrane results in Joule heating during the extraction process which may follow by punctuation of the organic membrane, increasing of the current level and bubble formation due to electrolysis reactions. A mixture of 2-nitrophenyl octyl ether (NPOE), di-(2-ethylhexyl) phosphate (DEHP) and tris-(2-ethylhexyl) phosphate (TEHP) was immobilized in the pores of hollow fiber as the organic liquid membrane. Other effective parameters such as extraction time, ion balance and pulse frequency were optimized using the experimental design. Extraction recoveries in the range of 7.1–21.6% and satisfactory repeatability (2.1 < CV% < 4.5) were obtained. Limits of detection were 5, 10 and 30 ng mL⁻¹ for tryptophan, phenylalanine and histidine, respectively. The method offers acceptable linearity with correlation coefficients higher than 0.9979. Furthermore, the figures of merit of PEME are compared with the results from conventional electromembrane extraction (EME), which proves the advantages of the proposed technique. The method was applied to the determination and quantification of amino acids in foods and biological samples. Also, two-way PEME was employed as a novel approach for highly selective extraction of tryptophan as a model analyte to introduce an interesting ability of the proposed technique.     

人工神经网络紫外光度法同时测定甲基苯甲醛的三种同分异构体及其与偏最小二乘法的比较

同分异构体的同时测定一直是分析化学领域的热点和难点问题,本文将化学计量学中的多元校正方法,如偏最小二乘法和人工神经网络法与紫外分光光度法相结合,同时测定了紫外吸收光谱严重重叠的甲基苯甲醛的三种同分异构体混合体系中各组分的含量。确定了测定的最佳波长范围为230～304 nm;测得48个混合标样的吸光度值用于建立模型,其中,邻、间、对甲基苯甲醛的浓度范围分别为6.0～15.0、7.0～16.0和8.0～19.0 μg·mL-1。7个模拟样品作为监测集用于检验所建立模型的预测性能。本文还讨论了三种组分浓度比例对所建立模型预测性能的影响并确定了可以准确测定的浓度比例范围。所建立的方法用于模拟样品的测定,其回收率在84.00%与109.60%之间。与偏最小二乘法的测定结果比较,经成对t检验表明,两种方法对邻、间甲基苯甲醛测定结果无显著性差异;而对甲基苯甲醛的测定,人工神经网络法的测定结果优于偏最小二乘法。     

Electromembrane extraction using two separate cells: A new design for simultaneous extraction of acidic and basic compounds

Simultaneous extraction of acidic and basic analytes from a sample is seen to be a challenging task. In this work, a novel and efficient electromembrane extraction (EME) method based on two separate cells was applied to simultaneously extract and preconcentrate two acidic drugs (naproxen and ibuprofen) along with a basic drug (ketamine). Once both cells were filled with the sample solution, basic drug was extracted from one cell with the other cell used to extract acidic drugs. The employed supported liquid membranes for the extraction of acidic and basic drugs were 2‐ethyl hexanol and 1‐octanol, respectively. Under an applied potential of 250 V in the course of the extraction process, acidic, and basic drugs were extracted from a 3.0 mL aqueous sample solution into 25 μL acceptor solutions. The pH values of the donor and acceptor solutions in the cathodic cell were 5.0 and 1.5, respectively, the corresponding values in the anodic cell were, however, 8.0 and 12.5, respectively. The rates of recovery obtained within 20 min of extraction time at a stirring rate of 750 rpm ranged from 45 to 54%. With correlation coefficients ranging from 0.990 to 0.996, the proposed EME technique provided good linearity over a concentration range of 20–1000 ng/mL. The LOD for all drugs was found to be 6.7 ng/mL, while reproducibility ranged from 7 to 12% (n = 5). Finally, applying the proposed method to determine and quantify the drugs in urine and wastewater samples, satisfactory results were achieved.     

Electromembrane extraction and anodic stripping voltammetric determination of mercury(II) using a glassy carbon electrode modified with gold nanoparticles

This study presents a method for the selective determination of Hg(II) using electromembrane extraction (EME), followed by square wave anodic stripping voltammetry (SWASV), using a gold nanoparticle-modified glassy carbon electrode, (AuNP/GCE). By applying an electrical potential of typically 60 V for 12 min through a thin supported liquid membrane (1-octanol), Hg(II) ions are extracted from a donor phase (i.e., the sample solution) to an acidic acceptor solution (15 μL) placed in the lumen of a hollow fiber. The influences of experimental parameters during EME were optimized using face-centered central composite design. The calibration plot, established at a working voltage of 0.55 V (vs. Ag/AgCl), extends from 0.2 to 10 μg^.L^?1 of Hg(II). The limit of detection, at a signal to noise ratio of 3, is 0.01 μg^.L^?1 and the relative standard deviations (for 5 replicate determinations at 3 concentration levels) are between 7.5 and 8.7 %. The method was successfully applied to the determination of Hg(II) in spiked real water samples to give recoveries ranging from 89 to 97 %. The results were validated by cold vapor atomic absorption spectroscopy.

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Graphical abstract Hg(II) ions were extracted from a donor phase into an acidic acceptor phase (15 μL) placed in the lumen of a hollow fiber using electromembrane extraction. The acceptor phase was then analyzed using anodic stripping voltammetry.

     

Development and application of carbon nanotubes assisted electromembrane extraction (CNTs/EME) for the determination of buprenorphine as a model of basic drugs from urine samples

In this work carbon nanotubes assisted electromembrane extraction (CNTs/EME) coupled with capillary electrophoresis (CE) and ultraviolet (UV) detection was developed for the determination of buprenorphine as a model of basic drugs from urine samples. Carbon nanotubes reinforced hollow fiber was used in this research. Here the CNTs serve as a sorbent and provide an additional pathway for solute transport. The presence of CNTs in the hollow fiber wall increased the effective surface area and the overall partition coefficient on the membrane; and lead to an enhancement in the analyte transport. For investigating the influence of the presence of CNTs in the SLM on the extraction efficiency, a comparative study was carried out between EME and CNTs/EME methods. Optimization of the variables affecting these methods was carried out in order to achieve the best extraction efficiency. Optimal extractions were accomplished with NPOE as the SLM, with 200 V as the driving force, and with pH 2.0 in the donor and pH 1.0 in the acceptor solutions with the whole assembly agitated at 750 rpm after 25 min and 15 min for EME and CNTs/EME, respectively.     

Simplified cloud point extraction for the preconcentration of ultra-trace amounts of gold prior to determination by electrothermal atomic absorption spectrometry

A simple and sensitive cloud point extraction method has been developed for the preconcentration of ultra-trace amounts of gold as a prior step to its determination by electrothermal atomic absorption spectrometry. It is based on the extraction of gold in hydrochloric acid medium using the non-ionic surfactant polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) without adding a chelating agent. The preconcentration of a 50 mL sample solution was thus enhanced by a factor of 200. The resulting calibration graph was linear in the range of 10–200 ng L⁻¹ with a correlation coefficient of 0.9993. The limit of detection (3s) obtained under optimal conditions was 2.0 ng L⁻¹. The relative standard deviation for 10 replicate determinations at a 100 ng L⁻¹ Au level was 3.6%. The method was applied to the ultra-trace determination of gold in water and copper samples.     

Comparison of extraction methods for the analysis of natural dyes in historical textiles by high-performance liquid chromatography

Different methods for the extraction of Dactylopius coccus Costa, Rubia tinctorum L., Isatis tinctoria L., Reseda luteola L., Curcuma longa L. and Cotinus coggygria Scop. from wool fibres are investigated using high-performance liquid chromatography with diode array detector (HPLC-DAD). The efficiencies of five extraction methods which include the use of HCl (widely used extraction method), citric acid, oxalic acid, TFA and a combination of HCOOH and EDTA are compared on the basis of the (a) number, (b) relative quantities, measured as HPLC peak areas and (c) signal-to-noise ratios (S/N) of the compounds extracted from the wool substrates. Flavonoid glycosides and curcuminoids contained in R. luteola L. and C. longa L., respectively, according to liquid chromatography with mass spectrometry (LC-MS) identifications, are not detected after treating the fibres with HCl. All the other milder methods are successful in extracting these compounds. Experiments are performed using HPLC-DAD to compare the HPLC peak areas and the S/N of the following extracted compounds: indigotin, indirubin, curcumin, demethoxycurcumin, bisdemethoxycurcumin, fisetin, sulfuretin, luteolin, luteolin-7-O-glucoside, apigenin, carminic acid, alizarin, puruprin and rubiadin. It is shown that the TFA method provides overall the best results as it gives elevated extraction yields except for fisetin, luteolin, apigenin and luteolin-7-O-glucoside and highest S/N except for fisetin and luteolin-7-O-glucoside. It is noteworthy that treatment of the fibres with the typical HCl extraction method results overall in very low S/N. The TFA method is selected for further studies, as follows. First, it is applied on silk dyed samples and compared with the HCl method. The same relative differences of the TFA and HCl methods observed for the wool dyed samples are reported for the silk dyed samples too, except for rubiadin, luteolin and apigenin. Thus, in most cases, the nature of the substrate (wool or silk) appears to have negligible effects on the relative difference of the two extraction methods. Second, the selected TFA method is applied to treat wool and silk historical samples extracted from textiles of the Mamluk period, resulting in the identification of several colouring compounds. In all extraction methods mentioned above, DMSO is used to dissolve the dyes, after acid treatment.