Derivatization Temperature Research Articles

Determination of the stability of sodium cyclamate during deep-frying using HPLC.

The oil used to fry food is often used multiple times to reduce costs. However, when foods containing sweeteners are processed in this way, the sweeteners may produce substances harmful to the body as a result of repeated frying at high temperatures. This article investigated the stability of sodium cyclamate during deep-frying by HPLC using a pre-column derivatization method. The results showed that cyclohexylamine was a decomposition product of a standard sample of sodium cyclamate when deep-fried at 200°C for 25 min. A pre-column derivatization/HPLC method was established to determine cyclohexylamine, a decomposition product of sodium cyclamate, under these conditions. Dansyl chloride was used as the derivatization reagent, the derivatization temperature was 60°C, the derivatization time was 20 min, the pH of sodium bicarbonate buffer solution was 11, and the concentration of dansyl chloride was 2.0 mg/mL. Detection was carried out by using an Agilent 1260 high-performance liquid chromatograph coupled with an ultraviolet detector. The ultraviolet detection wavelength was 254 nm, and the mobile phase was acetonitrile-1.0 g/L potassium dihydrogen phosphate solution at a flow rate of 1.0 mL/min. Gradient elution was adopted, the peak of the cyclohexylamine derivative appeared at a retention time of 17.75 min, and the peak area response value was the largest. The methodological validation analysis showed that the detection limit of cyclohexylamine was 0.5 mg/kg, the quantification limit was 2.0 mg/kg, and the spiked recoveries were in the range of 99.37-110.16%. The relative standard deviations (RSDs) were in the range of 0.17-1.26%. Four samples were tested and analyzed by the established method, and cyclohexylamine was not detected.

Influence of Derivatization Temperature and Butylated Hydroxytoluene on the Content of Malondialdehyde in Liver Homogenates

Influence of Derivatization Temperature and Butylated Hydroxytoluene on the Content of Malondialdehyde in Liver Homogenates

Biosignature preparation for ocean worlds (BioPOW) instrument prototype

In situ sampling missions to detect biosignatures on ocean worlds requires thorough sample preparation to manage the expected chemical complexity of such environments. Proposed instruments must be capable of automatic liquid sample handling to ensure sensitive and accurate detections of biosignatures, regardless of the initial chemical composition. Herein, we outline the design, build, and test of the integrated Biosignature Preparation for Ocean Worlds (BioPOW) system capable of purifying amino acids from icy samples. This four step modular instrument 1) melts ice samples, 2) purifies amino acids via cation exchange chromatography, 3) concentrates via vacuum drying, and 4) derivatizes amino acids to volatilize and enable detection with downstream analytical instruments. Initial experiments validated the thermal performance of the system by melting ice in the sample cup (1 mL sample, 3°C–28°C, <5 min, 1.4 kJ) and heating the derivatization tank past the concentration temperature (20°C–60°C, 12 min, 3.6 kJ) to the derivatization temperature (60°C–90°C, 25 min, 7.5 kJ). Later experiments investigated important factors for automatic cation exchange using a design of experiments approach, and found that initial salt concentration, sample and eluate flow rates, and water wash volumes all play significant roles in reducing conductivity (1.1 x–6.7 x) while maintaining phenylalanine yields between 31% and 94%. The modules were then integrated into a 12 cm × 20 cm × 20 cm fieldable platform for analysis, and the maturation of this design for future spaceflight is discussed.

HiSorb sorptive extraction for determining salivary short chain fatty acids and hydroxy acids in heart failure patients

Variations in salivary short-chain fatty acids and hydroxy acids (e.g., lactic acid, and 3-hydroxybutyric acid) levels have been suggested to reflect the dysbiosis of human gut microbiota, which represents an additional factor involved in the onset of heart failure (HF) disease. The physical–chemical properties of these metabolites combined with the complex composition of biological matrices mean that sample pre-treatment procedures are almost unavoidable. This work describes a reliable, simple, and organic solvent free protocol for determining short-chain fatty acids and hydroxy acids in stimulated saliva samples collected from heart failure, obese, and hypertensive patients. The procedure is based on in-situ pentafluorobenzyl bromide (PFB-Br) derivatization and HiSorb sorptive extraction coupled to thermal desorption and gas chromatography-tandem mass spectrometry. The HiSorb extraction device is completely compatible with aqueous matrices, thus saving on time and materials associated with organic solvent-extraction methods. A Central Composite Face-Centred experimental design was used for the optimization of the molar ratio between PFB-Br and target analytes, the derivatization temperature, and the reaction time which were 100, 60 °C, and 180 min, respectively. Detection limits in the range 0.1–100 µM were reached using a small amount of saliva (20 µL). The use of sodium acetate-1-13C as an internal standard improved the intra- and inter-day precision of the method which ranged from 10 to 23%. The optimized protocol was successfully applied for what we believe is the first time to evaluate the salivary levels of short chain fatty acids and hydroxy acids in saliva samples of four groups of patients: i) patients admitted to hospital with acute HF symptoms, ii) patients with chronic HF symptoms, iii) patients without HF symptoms but with obesity, and iv) patients without HF symptoms but with hypertension. The first group of patients showed significantly higher levels of salivary acetic acid and lactic acid at hospital admission as well as the lowest values of hexanoic acid and heptanoic acid. Moreover, the significant high levels of acetic acid, propionic acid, and butyric acid observed in HF respect to the other patients suggest the potential link between oral bacteria and gut dysbiosis.

Fluoride derivatization-enabled sensitive and simultaneous detection of biomarkers for nitrogen mustard in human plasma and urine via gas chromatography tandem mass spectrometry.

Methyl-diethanolamine (CAS: 105-59-9), ethyl-diethanolamine (CAS: 139-87-7), and triethanolamine (CAS: 102-71-6) were identified as the degradation products and bio-markers of nitrogen mustard exposure. Sensitive and convenient detection methods for amino alcohol are of great importance to identify nitrogen mustard exposure in forensic analysis. Herein, analytical methods including gas chromatography-tandem mass spectrometry combined with heptafluorobutyryl derivatization and solid phase extraction were established for retrospective detection of the biomarkers in human plasma and urine samples. The efficiency of the method was improved by optimizing the conditions for sample preparation and the GC-MS/MS method. The optimization included the derivatization temperature, reaction time, reagent dosage and solid phase extraction cartridges, eluent and pH of the loading sample. The results indicated that the SCX cartridge resulted in better enrichment and purification effects, and the best recovery could be obtained with pH = 3-4 for the loading samples and an eluent of 2 mL 10% NH4OH/MeOH. The GC-MS/MS parameters were also optimized for better specificity and sensitivity. The established method was fully validated for each analyte both in plasma and urine matrixes. The linear range of analytes in plasma was 1.0-1000 ng mL-1 with a correlation parameter (R2) of ≥0.994, intra-day/inter-day accuracy of 93.7-117%, and relative standard deviation (RSD) of ≤6.5%. Meanwhile the results in urine were 1.0-1000 ng mL-1 with R2 of ≥0.996, intra-day/inter-day accuracy of 94.3-122%, and RSD of ≤6.6%. The detection limit of the analytes was 1.0 ng mL-1. The method was applied for the detection and identification of trace amino alcohols present in urine samples dispatched by the Organization for the Prohibition of Chemical Weapons (OPCW) and the results were confirmed to be correct.

Optimization and validation of ultrasensitive GC–MS/MS method to measure oxidatively induced DNA damage products and role of antioxidants in oxidation mechanism

Oxidation of DNA due to exposure to reactive oxygen species (ROS) is a major source of DNA damage. ROS induced damage to DNA plays an important role in some diseases such as various cancers, aging and neurodegenerative diseases. The detection of DNA oxidation products plays a major role in assessing the mutagenicity potential of specific exposure. The GC–MS/MS method was developed for the ultrasensitive determination of individual DNA damage products. The validation results revealed that the proposed method was reliable and sensitive. Multiple response surface methodology (MRSM) was used to optimize derivatization conditions of oxidatively DNA base damage products before GC–MS/MS analysis. The optimum derivatization conditions were determined as 40 min for derivatization time, 120 °C for derivatization temperature and 1.4 for BSTFA/pyridine ratio under nitrogen atmosphere. The effects of thymol, carvacrol and thymoquinone as antioxidants were investigated on oxidative DNA damage. The determination of the oxidatively induced DNA damage products was performed after adding DNA and antioxidants with different concentrations under oxidative stress. Eighteen DNA base damage products were analyzed simultaneously using GC–MS/MS. This study showed a significant decrease in the amount of DNA base damage products when the antioxidants were present in the medium.

Detection of residual formaldehyde in N-butyl-2-cyanoacrylate by high-performance liquid chromatography with rhodamine B hydrazide

Rhodamine B hydrazide (RBH) was prepared as a new derivatizing reagent for residual formaldehyde in a drug such as N-butyl-2-cyanoacrylate (NBCA). RBH reacted with formaldehyde rapidly at room temperature, and the resulting derivative can be detected sensitively at 238 nm. After optimizing the derivatization and chromatographic separation conditions, RBH as a pre-column derivatizing reagent has been successfully used for the analysis of formaldehyde in real NBCA samples by high-performance liquid chromatography (HPLC). The detection limit of the method is 0.004 μg/mL for formaldehyde, and the recovery is 94.0%-96.6%. Most notably, compared with the previous HPLC methods, the developed method has the advantages of mild derivatization temperature, short derivatization time and high sensitivity.

Simultaneous determination of seven perfluoroalkyl carboxylic acids in water samples by 2,3,4,5,6-pentafluorobenzyl bromide derivatization and gas chromatography-mass spectrometry

A new derivatization reagent, 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr), was employed to determine seven perfluoroalkyl carboxylic acids (PFCAs) simultaneously in tap water with gas chromatography-mass spectrometry (GC-MS) technique in this study. Firstly, seven PFCAs were derivatized to their corresponding esters under alkaline condition. The derivatization conditions including the amount of PFBBr and K2CO3, derivatization temperature and time were optimized to increase the derivatization efficiency. The 14 tap water samples collected from different places of China were enriched and purified through solid phase extraction pretreatment. The limits of detection (LODs) and the limits of quantitation (LOQs) ranged from 0.1 ng/L to 0.28 ng/L and from 0.3 ng/L to 0.84 ng/L, respectively. The new method offers a linear relationship in the range from 2 ng/L to 2000 ng/L, and the correlation coefficients ranged from 0.9938 to 0.9994. The results showed that GC-MS combined with pre-column derivatization is a reliable method for the analysis of PFCAs in the aqueous environment.

Rapid Determination of Ammonia in Biological Samples by GC-MS Derivatization Method.

Objective To establish a qualitative and quantitative method to determine ammonia in biological samples by gas chromatography-mass spectrometry （GC-MS）. Methods A heptafluorobutyryl chloride derivatization method was used. GC-MS was used for determination. The effects of different pH conditions, derivatization temperature, time and different extraction solvents on the test results were investigated. The pretreatment conditions were optimized. Results This method could accurately detect the ammonia content in blood, and the limit of detection was determined to be 0.1 μg/mL. The target component showed good linearity in the range of 0.5-200.0 μg/mL （R2=0.987 7）. The relative standard deviation range of intra-day precision was 2.59%-3.88%. The relative standard deviation range of inter-day precision was 3.21%-3.76%. Conclusion The method showed good sensitivity, stability and specificity, therefore can be used for forensic toxicology analysis and clinical biochemical detection.

Optimization and validation of in-situ derivatization and headspace solid-phase microextraction for gas chromatography–mass spectrometry analysis of 3-MCPD esters, 2-MCPD esters and glycidyl esters in edible oils via central composite design

This study aimed to develop a headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS–SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long.

Determination of testosterone and corticosterone in feathers using liquid chromatography-mass spectrometry

Feathers gradually accumulate hormones and reflect long-term average plasma steroid levels during their growth. Feather hormone levels thus provide for the measurement of plasma hormones concentrations integrated over a period of several days or weeks. In this study, we focused on the development of a method to determine testosterone (TEST) and corticosterone (CORT) levels in extracts from feathers of small bodied birds with a limited amount of feathers available per individual. For this purpose, the method had to be verified for a small weight of samples. The present study describes the effect of the conditions of sample preparation and keto-derivatisation on the sensitivity of the LC–ESI–MS/MS analysis of TEST and CORT. Generally, chemical derivatization improves the sensitivity and selectivity of LC–MS/MS analysis. It can be used particularly in situations when the total amount of collected sample is limited (such as in our studies). Both the conditions of feather sample preparation (the selection of the extraction solvent, the time of extraction, and the conditions of solid phase extraction) and the reaction conditions affecting the formation of keto-derivatives (such as reaction temperature and reaction time) were tested. Methanol as the extraction solvent, 8 h as the extraction time, 50 °C as the reaction temperature of derivatization, and 90 min as the reaction time of derivatization are the most suitable conditions in terms of achieving a high sensitivity of analyses. Calibration curves are linear, at least in the range 25–2500 pg mL−1, which is usually found in feather extracts. The limit of detection (LOD) for TEST and CORT was 1.0 and 0.3 pg per mL, respectively. The limit of quantification (LOQ) for TEST and CORT was 3.3 and 1.0 pg per mL, respectively. The optimized procedure was successfully applied for the analysis of TEST and CORT in real feather samples. The method could be used in a variety of research direction including wildlife, agricultural or veterinary studies.

Bio-based succinic acid sample preparation and derivatization procedure optimisation for gas chromatography-mass spectrometry analysis

This study focused on bio-based succinic acid sample preparation and derivatization conditions optimization using GC-MS analytical method. Succinic acid, the precursor of a wide range bio-compounds, especially it is important in accumulation of mitochondrial metabolite succinate (citric acid cycle) and during ischemia controls reperfusion injury through mitochondrial reactive oxygen production. Accurate determination of analytes is the key in metabolomics to use as low molecular biomarkers in case to improve diagnostic methods. Methods. Gas chromatography-mass spectrometry (GC-MS) method. For the quantitative determination of the succinic acid applied derivatization process by silylation using -bis- (trimethylsilyl) -trifluoroacetamide (BSTFA). Results. The derivatization agent BSTFA, the derivatization time of 3-4 hours and derivatization temperature at 70 °C were selected as the optimal derivatization condition for quantification of succinic acid by GС/MS in biological samples. The results show that GC-MS SIM method with evaporation was the most effective to quantify succinate in biological samples after ischemia/reperfusion injury. Selected ion monitoring (SIM) allowed to monitor a subset of fragments with their related mass values in a certain retention time (RT) range for a set of targets. Conclusions. DC – MS has several advantages for measurements of succinate concentration in small kidney tissue samples (lyophilized mitochondria). The method can be applied in small pieces of tissue - biopy samples, tissues from various organs

Optimization of cationic (Q)-paper for detection of arboviruses in infected mosquitoes

Previously (Glushakova et al. 2017), a cellulose-based cationic (Q) paper derivatized with quaternary ammonium groups was shown to be a convenient platform to collect, preserve, and store nucleic acids (NAs) derived from mosquito vectors infected with pathogens for surveillance. NAs bind electrostatically to Q-paper, but the quantity of NA bound depends on the paper’s binding capacity. To optimize the original technology for mosquito surveillance, factors that affected NA absorbance on Q-paper were evaluated. Sixteen variations of Q-paper were prepared with modifications of the derivatizing reagents and derivatization temperature. The binding capacities of these variations were determined first with 1,3,5-benzenetricarboxylic (BTCA), then viral RNA (purified or in infected mosquito samples) was used for validation. For this, samples with Zika (ZIKV) and chikungunya (CHIKV) RNA or virus-infected Aedes aegypti mosquito bodies were applied to sixteen Q-paper variants. Washing the paper samples with water versus elution with aqueous salt (1 M) gave samples that were analyzed for viral RNA by a PCR-based direct Luminex hybridization assay. The comparison ranked the Q-paper binding capacities from the lowest to the highest. The Q-paper with the highest RNA binding capability was further validated with ZIKV- and CHIKV-infected mosquito saliva.

Vortex-assisted liquid-liquid microextraction based on hydrophobic deep eutectic solvent for determination of malondialdehyde and formaldehyde by HPLC-UV approach

A simple, and cost-effective vortex-assisted liquid-liquid microextraction (VALLME) based on hydrophobic deep eutectic solvent (DES) has been developed to extract malondialdehyde (MDA) and formaldehyde (FA) after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Following the extraction process, a high performance liquid chromatography equipped with UV–Vis detector (HPLC-UV) was used for separation and quantification of the target analytes. The key variables affecting the derivatization process (concentration of DNPH, derivatization time, and derivatization temperature) were optimized by a central composite design (CCD). The effective parameters of VALLME including pH of the extraction medium, ionic strength, extracting agent (DES) volume, dispersive solvent volume, centrifugation rate, centrifugation time, and time of vortex were studied by a fractional factorial design to identify the significant factors effective in the extraction process. In the next step, a CCD was used to obtain the optimum conditions of the effective parameters. Under optimal conditions, good linearities (R2 > 0.99) in the concentration ranges of 5–3000 and 20–2000 ng mL−1 were obtained for MDA and FA, respectively. The detection limits of MDA and FA were found as 2.0 and 10.0 ng mL−1, respectively. The method was successfully applied to the quantification of both analytes in three different real samples (human urine, apple juice and rain water) and satisfactory results in terms of recoveries (91–112%) were achieved.

A simple one-step ultrasonic-assisted extraction and derivatization method coupling to high-performance liquid chromatographyfor the determination of ε-aminocaproic acid and amino acids in cosmetics

Nowadays, the safety of cosmetics is a widespread concern. Amines are common cosmetic additives. Some of them such as amino acids are beneficial. Another kind of amines, however, ε-aminocaproic acid (EACA) is prohibited to add into cosmetics for its adverse reactions. In this study, a simple, rapid, sensitive and eco-friendly one-step ultrasonic-assisted extraction and derivatization (UAE-D) method was developed for determination of EACA and amino acids in cosmetics by coupling with high-performance liquid chromatography (HPLC). By using this sample preparation method, extraction and derivatization of EACA and amino acids were finished in one step in ultrasound field. During this procedure, 4-fluoro-7-nitrobenzofurazan (NBD-F)was applied as derivatization reagent. The extraction conditions including the amount of NBD-F, extraction and derivatization temperature, the ultrasonic vibration time and pH value of the aqueous phase were evaluated. Meanwhile, the extraction mechanism was investigated. Under optimized conditions, the method detection limits were 0.086–0.15 μg/L, and method quantitation limits were 0.29–0.47 μg/L with RSDs less than 3.7% (n = 3). The recoveries of EACA and amino acids obtained from cosmetic samples were in range from 76.9% to 122.3%. Amino acids were found in all selected samples and quantified in range from 1.9 ± 0.9 to 677.2 ± 17.9 μg/kg. And EACA was found and quantified with the contents of 1284.3 ± 22.1 μg/kg in a toner sample. This UAE-D-HPLC method shortened and simplified the sample pretreatment as well as enhanced the sensitivity of analytical method. In our record, only 10 min was needed for the total sample preparation process. And the method detection limits were two orders of magnitude less than literature reports. Furthermore, we reduced the consumption of solvent and minimized the usage of organic solvents, which made our method moving towards green analytical chemistry. In brief, our UAE-D-HPLC method is a simple, rapid, sensitive and eco-friendly analytical method for the determination of EACA and amino acids in cosmetics.

Development of a Method for Rapid Determination of Morpholine in Juices and Drugs by Gas Chromatography-Mass Spectrometry.

A reliable derivatization method has been developed to detect and quantify morpholine in apple juices and ibuprofen with gas chromatography-mass spectrometry. Morpholine can react with sodium nitrite under acidic condition to produce stable and volatile N-nitrosomorpholine derivative. In this experiment, various factors affecting the derivatization and extraction process were optimized, including volume and concentration of hydrochloric acid, quantity of sodium nitrite, derivatization temperature, derivatization time, extraction reagents, and extraction time. The derivative was extracted with dichloromethane and determined by gas chromatography-mass spectrometry. The linearity range of morpholine was 10–500 μg·L−1 with good correlation, and limits of detection (LOD) and limits of quantification (LOQ) were 7.3 μg·L−1 and 24.4 μg·L−1, respectively. Low, medium, and high concentrations of morpholine were added in apple juices and ibuprofen samples to evaluate standard recovery rate and relative standard deviation. The spiked recovery rate ranged from 94.3% to 109.0%, and the intraday repeatability and interday reproducibility were 2.0%–4.4% and 3.3%–7.0%, respectively. The developed method has good accuracy and precision. This quantitative method for morpholine is simple, sensitive, rapid, and low cost and can successfully be applied to analyze the residual morpholine in apple juices and drug samples.

Validation of UPLC method on the determination of formaldehyde in smoked meat products

ABSTRACTThe study was carried out to establish a formaldehyde (FA) detection method in smoked meat products with ultra-performance liquid chromatography (UPLC) method. The high-performance liquid chromatography method was developed by using steam distillation as extraction method and then derived by2,4-dinitrophenylhydrazine (DNPH). The final optimum conditions of derivatization for UPLC method were determined as follows: DNPH dosage of 0.3 mL, derivatization temperature of 60°C, derivatization time of 60 min, and twice extraction. This method was further applied to determine the content of FA in the smoked meat products from five companies. The internal FA in the smoked meat products ranged from 25.55 mg/kg meat to 49.20 mg/kg meat, and the surface FA was 34.04 mg/kg meat to 165.25 mg/kg meat. Thus, this study establishes a simple, fast, and reliable method for the analysis of FA in smoked meat products.

Comparison of newly developed hydroxyl-functionalized monodisperse HILIC columns new HILIC column

ABSTRACTIn this study, new hydroxyl-functionalized monodisperse polymeric hydrophilic interaction chromatography (HILIC) columns were developed using different derivatization agents. In addition, the influences of derivatization temperature of the best agent and polymer composition on the separation were investigated under HILIC conditions. Monodisperse–porous hydrophilic particles were synthesized by the seeded polymerization method using 3-chloro-2-hydroxypropile methacrylate (HPMA-CL) and ethylene glycol dimethacrylate (EGDMA) monomers. The chloropropyl terminal ends of the poly(HPMA-Cl-co-EGDMA) particles were derivatized with amine group of ethanolamine (EA), diethanolamine, and triethanolamine (TEA) at 80°C through nucleophilic reaction. The performance of synthesized particles was evaluated with the amount of ligand on the particle surfaces, column backpressure, and separation power under HILIC condition. TEA was found to be the best derivatization agent for the separation of toluene, acrylamide, thymine, adenine, and cytosine in respect to resolution factors (>1.5 for all analytes) and theoretical plate numbers (64.562 N/m for acylamide). Upon determination of the best ligand, then the effect of different derivatization temperatures and polymer composition on TEA performance was investigated. Of all the tested polymer compositions, the chromatographic performance of TEA-M-80 (the derivatization of TEA at 80°C together with M polymer composition) was found to be the best.

Improved conventional and microwave-assisted silylation protocols for simultaneous gas chromatographic determination of tocopherols and sterols: Method development and multi-response optimization

This paper reports on improved conventional thermal silylation (CTS) and microwave-assisted silylation (MAS) methods for simultaneous determination of tocopherols and sterols by gas chromatography. Reaction parameters in each of the methods developed were systematically optimized using a full factorial design followed by a central composite design. Initially, experimental conditions for CTS were optimized using a block heater. Further, a rapid MAS was developed and optimized. To understand microwave heating mechanisms, MAS was optimized by two distinct modes of microwave heating: temperature-controlled MAS and power-controlled MAS, using dedicated instruments where reaction temperature and microwave power level were controlled and monitored online. Developed methods: were compared with routine overnight derivatization. On a comprehensive level, while both CTS and MAS were found to be efficient derivatization techniques, MAS significantly reduced the reaction time. The optimal derivatization temperature and time for CTS found to be 55°C and 54min, while it was 87°C and 1.2min for temperature-controlled MAS. Further, a microwave power of 300W and a derivatization time 0.5min found to be optimal for power-controlled MAS. The use of an appropriate derivatization solvent, such as pyridine, was found to be critical for the successful determination. Catalysts, like potassium acetate and 4-dimethylaminopyridine, enhanced the efficiency slightly. The developed methods showed excellent analytical performance in terms of linearity, accuracy and precision.

Validation and application of an analytical method for the determination of selected acidic pharmaceuticals and estrogenic hormones in wastewater and sludge

ABSTRACTThis study was undertaken to develop an extraction method for seven acidic pharmaceuticals and five steroidal estrogens from wastewater, treated wastewater and sludge samples. The temperature and time of sample derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide was optimized. Our results show that pretreatment combined with solid phase extraction (SPE) for wastewater samples (using an ENVI-C18 cartridge) and liquid-solid extraction combined with SPE (using an HLB cartridge) for sludge samples increased the analytical efficiency for acidic pharmaceuticals and estrogenic hormones using gas chromatography-mass spectrometry (GC-MS). The derivatization conditions were optimized at 40°C for 2 h. In addition, the derivatized samples were stable at ambient temperature. The new method was validated and applied to the analysis of real wastewater and discharged sludge samples from a local wastewater treatment plant. Except for 17α-ethinylestradiol, all acidic pharmaceuticals and estrogens were detected in the influent, effluent and discharged sludge samples. The concentrations of these compounds were particularly high in the discharged sludge samples.