High-Performance Liquid Chromatography of Domoic Acid,a Marine Neurotoxin,with Application to Shellfish and Plankton

Abstract

A recent outbreak of poisoning resulting from the consumption of cultured blue mussels (Mytilus edulis L.) from a localized area in Eastern Canada has been attributed to the presence of domoic acid (1), a relatively rare neurotoxic amino acid, previously found only in some algae of the family Rhodomelaceae. Studies on aqueous extracts of shellfish tissue indicated that the toxin and several of its isomers could be separated (and isolated in sufficient amounts for subsequent structural identification) by reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet (UV) diode array detection (DAD). Aqueous acetonitrile containing 0.1% v/v trifluoroacetic acid was used as mobile phase. As the retention time and characteristic UV absorption spectrum of 1 (λ_max = 242 nm) permit unequivocal identification, the HPLC-DAD procedure was refined with a microbore column to provide a rapid (5 min), sensitive (0.3 ng detection limit) and reproducible assay method for the determination of 1 in shellfish tissue. Extraction was accomplished by boiling homogenized shellfish tissue for 5 min with distilled water. Extracts were taken through an octadecylsilica solid phase extraction clean-up prior to HPLC. This method has been applied to a variety of shellfish and phytoplankton samples.

BRIEF

Reversed-phase HPLC with ultraviolet diode array detection was used to analyze shellfish tissue and phytoplankton extracts for domoic acid. A rapid (5 min) and sensitive (0.3 ng detection limit) assay is presented.     

Optimization of a Procedure for Extraction of Nucleotides from Plasma and Erythrocytes Prior to HPLC Analysis

Abstract

The efficiency of extraction of nucleotides from plasma and erythrocyte samples by means of the Khym TCA¹ - amine-Freon^R procedure was investigated.

Maximum efficiency of recovery was found when TCA concentrations greater than 9% were used to extract the nucleotides of cytosine, adenine and guanine from plasma and erythrocytes. The recovery from the erythrocyte matrix was 20% lower than that from the plasma matrix and 40% lower than the recovery of the same nucleotides from water. It was also found that using the exact amount of amine solution to neutralize the TCA resulted in increased recovery of the nucleotides.     

Automated on-Line Dialysis and Column-Switching HPLC Determination of Flumequine and Oxolinic Acid in Fish Liver

Abstract

An automated method for residue analysis of oxolinic acid and flumequine in liver of Atlantic salmon is described. Oxolinic acid and flumequine are extracted from liver with 0.4 M phosphate buffer pH 10 and the extracts are automatically analysed by on-line dialysis and column-switching in an HPLC system. The limit of detection was 4 μg/kg for oxolinic acid and 7 μg/kg for flumequine with fluorescence detection. The on-line combination of dialysis and column-switching HPLC was shown to be a reliable technique for residue control of these drugs in fish liver.     

Derivatization of isolated endogenous butyrobetaine with 4'-bromophenacyl trifluoromethanesulfonate followed by high-performance liquid chromatography.

A method for the isolation and chromatography of butyrobetaine from plasma, urine, and liver is described. The recovery of [3H-methyl]butyrobetaine from spiked biological samples was from 76-80%. Spiked samples then were derivatized with 4'-bromophenacyl trifluoromethanesulfonate and the butyrobetaine 4'-bromophenacyl ester was isolated by high-performance liquid chromatography (HPLC). Radioactivity eluted in a single peak which co-chromatographed with authentic butyrobetaine 4'-bromophenacyl ester. Two identical liver specimens were treated according to this isolation procedure. Prior to derivatization, one specimen was treated with butyrobetaine hydroxylase. After derivatization, there was no butyrobetaine 4'-bromophenacyl ester peak in the specimen treated with butyrobetaine hydroxylase. The HPLC detection sensitivity to butyrobetaine 4'-bromophenacyl ester was 1 pmol injected with a signal-to-noise greater than 2:1.     

Isolation of Lipophilic Persistent Organic Pollutants From Human Breast Milk

Background: Lipid removal from biological samples can be achieved by addition of concentrated sulfuric acid. However, certain persistent organic pollutants (POPs) such as chlorophenols are decomposed by sulfuric acid treatment and, thus, a more gentle lipid reduction method is needed for extraction of many environmental contaminants from biological samples. Membrane dialysis extraction (MDE) is a non-disruptive method to extract POPs from biological matrices.

Methods: Human breast milk samples were spiked with radiolabelled p,p′-dichlorodiphenyl trichloroethane ([C-14]-DDT) as a POP proxy and extracted using solid phase extraction (SPE). The extracts obtained were dialyzed by MDE in low-density polyethylene tubings containing a mixture of n-hexane and dichloromethane for 24 h, 48 h, or 72 h.

Results: The lipid content was reduced by 86.2% after one dialysis cycle of 24 h using MDE, and 87.1% recovery of the [C-14]-DDT standard was obtained. The DDT recovery could be further increased up to 96.3% and 98.1% by repeating the dialyses for one or two more cycles, respectively. However, the increased [C-14]-DDT recovery includes a concomitant increase in lipid carryover from 13.8% with one dialysis cycle to 22.1% with three cycles.

Conclusion: An SPE procedure for extracting POPs from breast milk and dialytic conditions for isolation of the extracted POP with minimal lipid carryover was established. The method is nondestructive and acceptable recoveries can be obtained within a single solvent shift as demonstrated by spiking standards. The lipid carryover was minimized, and the method may be considered for lipid removal before HPLC or GC analysis of environmental contaminants.     

A Comparison of Benzo(A)Pyrene-4,5-Epoxide Hydrase Activity in Hamster Embryo Cells,Hepatocytes and Livers Using High-Pressure Liquid Chromatography

Abstract

The benzo(a)pyrene-4,5-epoxide (BP-4,5-epoxide) hydrase activities of intact hamster hepatocytes and embryo cells, and homogenates of these cells as well as of adult liver are compared. The product of the epoxide hydrase (EH) reaction, trans-4,5-dihydro-4,5-dihydroxybenzo(a)pyrene (BP-4,5-diol), was isolated by high-pressure liquid chromatography (HPLC) with a Waters Bondapak C₁₈/Corasil column and acetonitrile-water as the mobile phase. Using this procedure to determine BP-4,5-epoxide hydrase activity in intact cells, it was found that 266 nmoles of BP-4,5-diol/10⁶ cells were produced by hepatocytes while no diol formation was detected with embryo cells. EH activity in the intact hepatocytes was 8-fold greater than in hepatocyte homogenates.     

An Improved Gas-Liquid Chromatographic Method for the Analysis Of 1,1,1-Trichloro-2,2-BIS(p-Chlorophenyl) Ethane(p,p′-DDT) and Its Metabolites in Milk

Abstract

A rapid method has been developed, in which p,p′-DDT residues are extracted from milk samples with n-hexane, following treatment of the milk with concentrated sulfuric acid. The extract, containing p,p′-DDT residues is then cleaned up on a silica gel column. Electron capture gas chromatography was used to measure the efficiency of the extraction and cleanup procedure. An overall average recovery of 97% was obtained on samples at concentration levels of 0.05 to 1.00 ppm.     

Desalting and Freeze-Drying Techniques to Prepare Plant Derived Neutral Sugar Extracts for Quantitative HPLC

Abstract

Desalting and sample concentration are frequent prerequisites for the quantitative HPLC analysis of sugars and polyhydric alcohols in extracts of biological material. However, desalting using Dowex mixed-bed resins and sample concentration by conventional freeze-drying adversely affect the recovery of the carbohydrates being analysed, making quantitation almost impossible. In the present paper we report modified sample preparation procedures which overcome this technical problem. Efficient desalting was achieved by batchwise deionisation with an Amberlite mixed-bed deionisation resin, incorporating thymolphthalein to provide a sensitive indicator of resin exhaustion. Complete recovery of neutral sugars was possible provided the resin was subsequently washed with water. Concentration of dilute extracts with full recovery of neutral sugars was achieved by freeze-concentration using a Savant Speed-Vac centrifugal freeze-concentrator. The combination of these desalting and freeze-concentration procedures gave excellent recoveries of the neutral sugars together with dramatic improvements in HPLC column life and chromatographic resolution.     

Analysis of acetic acid extraction solutions by inductively coupled plasma mass spectrometry for the classification of solid waste

The direct analysis of acetic acid solutions in order to carry out waste classification by ICP-MS was investigated. Solid waste was leached with acetic acid solutions according to normalized procedures aiming at the determination of Ag, As, Ba, Cd, Cr, Pb and Se. Optimization of the ICP-MS instrumental parameters in extraction solutions was carried out. The formation of oxides and doubly charged ions was evaluated. Optimization of the RF power and nebulizer gas flow rate was also carried out. The procedure was applied to retorted shale, which was classified as a non-hazardous waste. In addition to ICP-MS, HR-CS F AAS was used for the analysis of the same samples. Accuracy of both techniques was verified by recovery tests. Precision, reported as RSD, was better than 3.6%. Both techniques could be used for solid waste classification, but ICP-MS allowed the determination of most of the elements in the extracts, whereas all the results obtained by HR-CS F AAS were below the detection limits. The developed procedure eliminates the need for digestion of the leachate, as required in one of the normalized procedures. The developed methods proved to be accurate, simple and fast for multielemental analyses and efficient for waste residue classification.     

Minimization of volatile nitrogen oxides interference in the determination of arsenic by hydride generation atomic absorption spectrometry

In this study emphasis was given to minimize the interference of volatile nitrogen oxides from digestion procedures with nitric acid on the determination of arsenic by hydride generation atomic absorption spectrometry (HG AAS). Sulfamic acid (SA) is proposed to minimize this interference by employing three procedures for the digestion of hair in closed systems: conventional and microwave (MW) heating in polytetrafluorethylene (PTFE) vessels and by MW heating in glass vials. Hair samples were digested with H₂SO₄+HNO₃ or HNO₃+H₂O₂ mixtures. Concentrated hydrochloric acid was added for the digestion for the procedure in glass vials. The accuracy of the procedures with PTFE vessels was verified by the spike recoveries of organic (p-aminobenzenearsonic acid and dimethyl arsinic acid, from 92 to 101%) and inorganic (sodium arsenate, from 98 to 102%) arsenic compounds. For the procedure in glass vials the recovery was from 86 to 97% for organic As and from 97 to 102% for inorganic As. The results obtained for a certified hair reference material using the three digestion procedures were well within the 95% confidence interval of the certificate when SA was added to the solutions. However, when SA was not added, recoveries were low and non-reproducible signals and high background levels were observed. Urea, benzoic acid and hydroxylamine hydrochloride were also studied (maximum As recovery of 90% using hydroxylamine hydrochloride) but the best results were obtained with use of SA.     

Chemical characterisation and hepatoprotective potential of Cosmos sulphureus Cav. and Cosmos bipinnatus Cav.

This study was conducted to validate the hepatoprotective activity of Cosmos sulphureus and Cosmos bipinnatus. Aqua-methanolic extracts of both plants were evaluated for the presence of various phyto-constituents through HPLC. Different doses of both plant extracts were administered to rats for nine days. Standard control was silymarin 100 mg/kg. Paracetamol 1 gm/kg was administered 3 h post treatment on 9th day for induction of hepatotoxicity. Blood was collected for the evaluation of liver biochemical markers and livers were removed for histopathological evaluation 24 h post-paracetamol treatment. HPLC analysis revealed the presence of quercetin, gallic acid, caffeic acid and chlorogenic acid in both plant extracts. The extracts of both plants decreased the level of alanine aminotransaminase and total bilirubin significantly (p < 0.05), dose dependently and protected hepatocytes from paracetamol-induced hepatotoxicity. It can be concluded that both plants may possess hepatoprotective activity possibly due to the presence of quercetin and phenolic compounds.     

High Performance Liquid Chromatographic Determination of Nordihydroguaiaretic Acid

Abstract

A high performance liquid chromatography (HPLC) method was developed for the detection and quantitation of nordihydroguaiaretic acid (NDGA). Very low concentrations of NDGA in various extracts are detectable, thus making the method more sensitive than other previously reported analytical techniques. NDGA was extracted from leaves of Larrea divaricata as well as from rodent food containing NDGA. Since rats are fed NDGA in studies that examine the development of renal cystic disease, we modified extraction procedures to permit isolation of NDGA from tissue and serum samples.     

Comparison of Methods for the Preparation of Sewage Sludge Samples Prior to the Spectrophotometric Determination of Phosphorus

Abstract

Three procedures for the preparation of sewage sludge samples prior to the colorimetric determination of phosphorus as “molybdenum blue” were evaluated. Using samples of the US EPA's municipal digested sludge as a reference material, sulfuric acid/ammonium persulfate digestion, muffle furnace ignition followed by extraction of the ash with hydrochloric acid, and direct extraction of the sewage sludge with sodium bicarbonate solution were compared in terms of phosphorus recovery as determined by colorimetric measurements. On the basisof phosphorus recovery, the samples prepared by muffle furnace ignition/hydrochloric acid extraction of the ash showed the best accuracy and precision. This procedure was also superior in terms of the time and effort expended in the preparation of the sewage sludge samples.     

Purification method for the isolation of monophosphate nucleotides from Champagne wine and their identification by mass spectrometry

Monophosphate nucleotides are difficult to identify in Champagne wine because they are present in small concentrations in a complex mixture. A method for the isolation, separation and identification of reference compounds, which achieved on average 79% recovery (except for cytidine derivatives), was developed and applied to wine. Some monophosphate nucleotides were then isolated from a Champagne wine aged on lees for 8 years, by ultrafiltration followed by a semi-preparative HPLC step using a strong anion-exchange column. The fraction obtained was subjected to HPLC in a reversed-phase column to remove the salt previously introduced, before identification of compounds by HPLC coupled to a mass spectrometer. For the first time in wine, 5'-IMP, 5'-AMP, 5'-CMP, 5'-GMP, 5'-UMP and the 3'- and/or 2'-isomers of the four latter compounds were identified by comparing their HPLC and electrospray ionization mass spectrometry data with those of reference nucleotides.     

A Radioimmunoassay for Serum and Urine Aldosterone by Celite Column Chromatography

Abstract

A relatively simple and rapid radioimmunoassay (RIA) for the measurement of aldosterone in serum and urine has been developed. The method involves extraction of 1 ml of serum or urine (after acid hydrolysis) with dichloromethane, followed by partition chromatography on celite microcolumns prior to RIA. Dextran coated charcoal is used for separation of free from antibody-bound aldosterone. The method is very sensitive, blanks are negligible and recovery is approximately The%. 80 coefficient of variation is 4. 3% (within assay) and 10. 4% (between assay). When known amounts of aldosterone were added to serum and urine pools containing low endogenous levels of this steroid recovery was quantitative. Aldosterone concentrations measured under various physiological conditions were in agreement with published data. Up to 150 samples can be assayed by 1 technician during 5 working days.     

全氟辛酸的3,4-二氯苯胺衍生化及高效液相色谱分析

介绍了一种可用于环境污染物全氟辛酸（PFOA）检测的高效液相色谱/紫外检测（HPLC/UV）分析方法。首先选用3,4-二氯苯胺为衍生化试剂,利用碳二亚胺法合成PFOA的酰胺化衍生产物（其在255 nm处紫外吸收最大）。然后确定四氢呋喃或水相介质中mg/L水平PFOA的衍生化条件及薄层硅胶色谱净化步骤。建立柱前衍生-HPLC/UV方法,以合成的全氟辛酸-3,4-二氯苯酰胺为对照品,外标法定量,PFOA上机测定的定量限为0.5 mg/L。通过加标回收试验评价方法的准确性,其中有机相及水相衍生法的回收率分别为91.8%~108.7%及40.1%~53.7%。与已报道的柱前衍生-HPLC/UV方法比较,本方法具有反应条件温和、衍生产物稳定、原料廉价易得、操作简单、成本低等优点。将本方法应用于光催化降解研究中PFOA的降解动力学实验,结果与液相色谱-质谱联用方法（LC/MS）的结果一致,说明本方法具有较好的应用前景。     

Determination of Lacinilene C 7-Methyl Ether by High Performance Liquid Chromatography

Abstract

An HPLC method is presented for the quantization of lacinilene C 7-methyl ether in cotton dusts. A standard of lacinilene C 7-methyl ether was isolated from extracts of gin trash and a new extraction procedure was developed that effected complete removal of lacinilene C 7-methyl ether from cotton dust. Total dust contains an average of 48.64 μg/g of lacinilene C 7-methyl ether, and the below 20 μm fraction contains 35.9 μg/g of lacinilene C 7-methyl ether.     

Use of Alkaline Degradation for the Analysis of Dihydrotriazines via High Pressure Liquid Chromatography

Abstract

An HPLC method is described for the determination of 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3′,4′-dichlorobenzyloxy)-1,3,5-triazine hydrochloride (WR 38839). The procedure required the isomerization of the drug sample by alkaline treatment with sodium hydroxide, as the parent compound was retained by the column. The reaction product of the drug was analyzed by HPLC using a strong cation exchange resin as the stationary phase and glycine buffer, pH 10.4 as the mobile phase. The product was isolated and identified by TLC, UV, IR, mass spectroscopy and elemental analysis. The postulated mechanism indicates that this would be a general analytical method for dihydrotriazine compounds. This technique, developed for the assay of the dihydrotriazine in an aqueous system, was successfully applied to rat urine samples spiked with the drug.     

Quantitative analysis of phytoestrogens in kudzu-root, soy and spiked serum samples by high-pressure liquid chromatography

A sensitive and reliable HPLC method that allows simultaneous quantification of phytoestrogens extracted from kudzu-root and soy preparations, and serum samples has been developed. Kudzu-root and soy preparations were mixed with 5 microg flavone and 15 microg rutin (internal standards) and the phytoestrogens were extracted by using solid-phase (C18) extraction cartridges. Blank or spiked serum samples were extracted by using either C18 cartridges or trichloroacetic acid-methanol extraction. The extracts were analyzed by the HPLC equipped with a reverse-phase (250 x 4 mm, C18) column and UV, diode-array or MS detector. A linear gradient of acetic acid and acetonitrile provided excellent separation of glycoside and aglycone-phytoestrogens from kudzu root and soy preparations. The C18 cartridge extraction of serum yielded excellent recovery of both glycoside- and aglycone-phytoestrogens, while the trichloroacetic acid-methanol extraction yielded excellent recovery of glycoside but poor recovery of aglycone compounds. UV and MS detectors were suitable for phytoestrogen analysis in plant and serum samples, while the diode-array detector was suitable for generating the UV absorbance curve for phytoestrogens.     

Determination of Penicillinase-Resistant Penicillins In Serum Using High-Pressure Liquid Chromatography

Abstract

A method for the determination of methicillin, oxacillin, cloxacillin, dicloxacillin, and nafcillin in serum using high-pressure liquid chromatography (HPLC) is described. The drugs were extracted from serum using a two-step procedure employing acetonitrile followed by methylene chloride. The extraction procedure concentrated the antibiotics in a smaller volume which allows more accurate determinations of low serum levels. The treated sera were analyzed by HPLC on a reverse-phase column and detected by ultraviolet light absorption at 254 nm. Serum concentrations were measurable as low as 0.5 μg/ml. Recovery procedures showed less than 2.5% variation in peak heights when the antibiotics were extracted from different pools of serum. No interfering absorption was found in extracts of serum samples pooled from healthy volunteers, from a commercial source, or from two serum pools from patients receiving a variety of other drugs. Two spiked serum specimens prepared for each antibiotic were assayed four times by HPLC and by the microbiological agar diffusion method. No significant statistical differences between the methods were observed. Control materials were assayed for between-batch and within-batch reproducibility in the presence or absence of an internal standard. Results for between-batch reproducibility demonstrate CV's of about 5%. This procedure provides a sensitive, specific, accurate, and rapid method for determining antibiotic levels in routine clinical specimens.