Online soil sampling for HPLC

The pyrethroid class of pesticides is widely used around the world for the control of insects in many areas, including forestry, animal care, agriculture, public health care and households. The EPA estimates that they are the active ingredients in more than 3500 registered products and their use is increasing as the more acutely toxic organophosphate-based pesticides are slowly being replaced.

That is not to say that pyrethroids are non-toxic. Their insecticidal effects are a result of altering the nerve function of the pests, which causes paralysis and leads to eventual death. In humans, the compounds act in a similar manner, affecting nerve and brain function to cause symptoms such as headaches, dizziness, nausea, convulsions and loss of consciousness. The effects can last several days.

In practice, pyrethroids are designed to degrade under ultraviolet light within a few days of application, so residues on plant surfaces or soil will not persist for very long. This was seen as an improvement over the related pyrethrins, from which they are derived. Pyrethrins are natural compounds originally extracted from the chrysanthemum but they are unstable under sunlight and quickly become inactive.

In soil, pyrethroids are retained by sorption and poor solubility in water and it is important to be able to estimate residual levels from an agricultural and environmental point of view. For samples containing trace amounts of pesticides, the obvious problem is extraction and preconcentration of the target compounds so that they can be detected during analysis. In general, this time-consuming step is carried out in several steps but Slovakian scientists have developed a single-step procedure that combines extraction and preconcentration and links it online with HPLC detection.

Milan Hutta, Maria Chalanyova and Martin Pagac from Comenius University, Bratislava, described their new procedure in the Journal of Separation Science for the recovery and analysis of three pyrethroids - kadethrin, cypermethrin and permethrin. Solid-liquid extraction, SPE and RP-HPLC were combined in series and the method was optimised using spiked soil samples.

In the first stage, an adsorbent was placed at the bottom of a short glass column and up to 200 mg of contaminated soil was loaded on top. The adsorbent had a dual role, acting as a sieve to retain the fine soil particles and an adsorbent to trap the pesticides. Silica was the preferred adsorbent of three tested because it prevented interfering coelutions and provided the best recoveries. In a flow-through extraction procedure, the best solvent was found to be a mixture of methanol and aqueous citric acid.

The liquid flow was directed towards an SPE column containing a phenyl-based adsorbent which trapped the three pyrethroids while the liquid flow was directed to waste. They were back-flushed with aqueous methanol to the HPLC system operating in large-volume injection mode, designed for low levels of analytes. Following separation on a C18 column, the compounds were monitored by UV detection at 270 nm for kadethrin and 235 nm for the others.

This approach led to recoveries of 81-84%, 56-59% and 58-63% for kadethrin, cypermethrin and permethrin, respectively. The corresponding detection limits achieved by large-volume injection of 1 mL solution were 4.5, 3.7 and 3.6 ng/mL and for dry soil they were 27, 32 and 29 ng/g, respectively.

The researchers described this procedure as "a solid sampling HPLC technique" which has rarely been implemented in the reported literature. They intend to refine it for the analysis of other types of compounds in soil, sediments and plants and declared that it will allow the analysis of soil samples that were collected after the suppression of a mosquito invasion in Bratislava in 2009.

The method will be particularly useful for the analysis of small samples such as sections of a soil column or the interface between soil and the roots of a plant. It could also be of assistance in environmental forensics, to measure small concentrations of pollutants across a contaminated site.

Related links:

* Journal of Separation Science 2010, 33, 134-142: "On-line flow-through extraction-preconcentration-large volume injection-RP LC for trace determination of pyrethroids in Slovak soil"

Foiling fuel fraud

The high price of petroleum-based fuel makes it an attractive target for fraudsters and thieves. On the small scale, employers who hold stocks of fuel, perhaps for a transport fleet, regularly report losses due to theft by their employees, with year on year increases seen in the EU.

On the larger scale, cheaper substitute fuels are used illegally by motorists. For instance, red diesel is being discovered increasingly in the engines of motor vehicles in the UK. This fuel is intended for use in off-road agricultural vehicles and is approximately 33% of the price of regular fuels due to a lower government tax rate. It is named red diesel due to the presence of a red dye added before distribution to help distinguish it from other fuels.

The practice of dyeing has become relatively common throughout the world. Aviation fuels are marked with a dye to ensure that aircraft are fuelled with the right fuel to avoid accidents. Gasoline (petrol) and diesel are also dyed to prevent fraud and help to provide evidence of fuel theft.

In order to protect the fuel tax system and prevent fraud, sensitive methods must be in place to detect dyes in fuels. This is especially the case when dyed fuels have been illegally treated to remove the dyes, so that cheaper fuels can be sold as more expensive ones to increase the revenue stream and subsequent profits. In these cases, the concentration of dyes will be very low.

There are a number of reported methods for analysing fuel dyes, including HPLC with detection by mass spectrometry, UV-visible spectroscopy and diode array detection. A further variation has been developed by scientists in Brazil and Germany, two countries where fuel dyeing has been established.

Maria Valnice Boldrin Zanoni from Sao Paulo State University, Frank-Michael Matysik from the University of Regensburg and Magno Aparecido Goncalves Trindade, who is affiliated to both universities, used HPLC with electrochemical detection. It was devised especially for the two anthraquinone dyes Solvent Blue 14 and Solvent Blue 35, and the azo dye Solvent Red 24.

Initially, the method was tested and optimised with standard solutions of the three dyes plus the azo dye Solvent Orange 7 and the anthraquinone dye quinizarin. The compounds were separated on a reversed-phase C8 column using an isocratic mixture of acetonitrile and ammonium acetate. The peak shapes and tails were improved and the retention times reduced by stepping the flow rate during the separation.

Dye elution was complete within 12 minutes, although quinizarin was not detected under any conditions. The remaining four dyes were detected with an electrochemical detector that had a glassy working electrode, an Ag/AgCl reference electrode and a platinum wire auxiliary electrode. The optimum applied potential was set to +0.8 V, at which the peak currents were at or near their maximum values and the background current was small and reproducible. The stepped chromatographic flow rate had no effect on the background current.

The method was applied to gasoline samples that were spiked with the dyes. Some extra peaks observed in the chromatograms, which increased the background current, were attributed to residual gasoline components. They also co-eluted with Solvent Orange 7, which ruled that dye out of the procedure.

The gasolines were subjected to two sample preparation procedures. A simple evaporation procedure to remove the hydrocarbon components gave poor recoveries (60 and 40%, respectively) for Solvent Blue 35 and Solvent Red 24 and good recovery for Solvent Blue 14.

An SPE method improved the recoveries when it was used in conjunction with the standard additions method for quantitation, raising those for Solvent Blue 35 and Solvent Red 24 to more than 78%. The detection limits were less than 0.1 mg/L.

The research team declared that HPLC with electrochemical detection by anodic oxidation will be suitable for the analysis of selected fuel dyes in a simple and rapid procedure, which will help to combat the adulteration and fraudulent sale of various types of petroleum-based fuels.

Related links:

* Electroanalysis 2010 (Article in Press): "Sensitive determination of water insoluble dyes used as marking of commercial petroleum products using high-performance liquid chromatography with electrochemical detection"

Scented toy story

Those Easter bunnies that look so cute in the stores around this time of year are very tempting. Just the gift for your favourite niece or granddaughter, or even your partner if you are feeling romantic. They might even be scented bunnies, adding to their allure, but that is not always a good thing.

Of the many fragrances used in children's toys, some are allergenic to humans. A study carried out in Denmark in 2006 revealed that 70% of children's products tested contained detectable levels of fragrance allergens, which are one of the most common causes of contact dermatitis in children.

The potential health risks associated with toys prompted the EU to revise its toy safety directive in 2009 for all toys placed onto the EU market, banning 55 fragrances. They can be present up to a low level, 100 µg/g, if it is technically unavoidable. A further 11 fragrances with weaker allergenic potential are allowed at concentrations above this value, as long as they are declared on the packaging.

A team of scientists based in Germany noted that direct contact is not the only way in which people can be contaminated by allergens. By definition, a fragrance is volatile, so it could also be inhaled and still initiate allergenic symptoms. So, this team, comprising Ines Masuck, Christoph Hutzler and Andreas Luch from the Department of Product Safety at the Federal Institute for Risk Assessment in Berlin, undertook a study of the emission of fragrances from toys, as well as their content.

The researchers developed an SPME-GC/MS procedure to measure the emission levels of allergens from scented toys held at 23 and 40°C. In addition, a solid-liquid extraction GC/MS method was applied to measure the allergen contents in the toys themselves. The procedures were used to measure 24 of the 66 allergens listed in the EU Directive, 13 that are banned and 11 that require declaration if present.

Initially, the SPME-GC/MS method was optimised using a mixture of fragrances. Five SPME fibres were found to perform well but an 85 µm polyacrylate fibre was selected because it gave the best combination of recovery, relative standard deviation and subsequent desorption in the GC injection port.

A piece of PVC material impregnated with all 24 allergens was used to determine the best extraction conditions. The optimum extraction time at 23 °C was 4 hours and the equilibration and extraction times at 40°C were set to 4 and 3 hours, respectively.

The fibres were inserted into the GC for analysis, using a cold injection system initialised at 100°C and raised at 12°C/min to 300°C. The fragrance components were allowed 60 s at the maximum temperature to desorb onto a 50% phenyl-methylpolysiloxane column which was also temperature programmed.

The eluting compounds were analysed by electron ionisation and were quantified using one ion each, with a combination of retention time and qualifier ions to confirm their identification. An external calibration curve was used for quantification. The method yielded detection limits which were less than 1 ng/cm3 at 23°C and up to 1.27 ng/cm3 at 40°C.

Allergen contents in the toys themselves, as opposed to the emitted quantities, were measured on the same GC/MS system following extraction of frozen, powdered samples with toluene-ethyl acetate.

The procedures were used to analyse 5 scented dolls purchased from online stores. Some of the dolls contained high levels of the plasticisers diethyl phthalate and diisobutyl adipate, as well as measurable amounts of permitted fragrances.

However, 3 banned fragrances were detected. The contents of coumarin (sweet, vanilla odour) and eugenol (spice, clove-like) were both less than 100 µg/g, which is allowable under the EU legislation. The main offender was benzyl benzoate, which is described as having a sweet, balsamic odour with fruity or berry overtones. It exceeded 100 µg/g in 3 of the dolls, so required declaration on the packaging. This declaration was absent.

Not surprisingly, emissions of the fragrances from the dolls were greater at the higher temperature, although the actual amounts given off depended on the original content in the dolls, as measured by GC/MS.

The results suggest that scented toys might present a risk to children by inhalation, as well as direct contact. Higher emissions at increased temperatures could become important when the child is holding the toy close to its body, or is playing in front of a fire or radiator.

The research team recommended that further studies are required to better characterise and assess the risks for children due to the inhalation of toy fragrance allergens during play.

Related Links:

*
Journal of Chromatography A 2010 (Article in Press): "Investigations on the emission of fragrance allergens from scented toys by means of headspace solid-phase microextraction gas chromatography-mass spectrometry"

Colourless flavonoids in pollen

Pollen is the unique source of all the nutrients that bees require for healthy growth. They use it to feed themselves as well as the larvae in the hive and without it, the hive would perish. Bees collect pollen from flowers and mix it with a sticky secretion from their stomachs, so that it can be stored in pollen baskets on their legs for transport to the hive.

Bee pollen is a mixture of plant pollen, bee saliva and nectar and is rich in proteins, carbohydrates, amino acids, pigments, vitamins and minerals. The actual composition and proportions of the various components of a particular pollen, like honey, are related to the distribution of the source plants. These components fix the composition so that quality control standards can be established and subsequent adulteration of the products can be detected.

This is an important factor because bee pollen, just like honey, has been used for millennia as a dietary supplement by humans. Many declarations have been made regarding the health benefits but, tellingly, the US FDA does not allow pollen marketers in the United States to make health claims, as there is currently no scientific basis for these.

The pigments present in bee pollen, consisting primarily of flavonoids and anthocyanins, account for the variation in colour of pollen and honey. However, other non-coloured flavonoids can also be present. and their presence in one particular bee pollen has attracted the attention of Iberian researchers.

Federico Ferreres from the University of Murcia at Espinardo in Spain and David Pereira, Patricia Valentao and Paula Andrade from Porto University, Portugal, became interested in bee pollen from the plant Echium plantagineum, also known as Paterson's curse. It is an invasive weed found in southern Europe and its bee pollen has been extensively studied. However, no work has been carried out on the phenolic compounds, including flavonoids, which might be present.

The researchers analysed bee pollen from central Portugal which had been confirmed to originate from E. plantagineum. An acidic methanol extract was subjected to HPLC with two detectors, a photodiode array detector and a mass spectrometer. HPLC is an important technique for separating the complex mixtures of flavonoids present in food extracts, especially when limited supplies of the sample prevent ready isolation and purification of the components.

The extract was separated on a reversed-phase octadecylsilica column operating at room temperature, with a mobile phase gradient of methanol in aqueous acetic acid. Twelve flavonoids eluting within 30 minutes were detected at a wavelength of 350 nm. Since the visible range covers 390-750 nm, these flavonoids were colourless.

The compounds were glycosides of quercetin, isorhamnetin and kaempferol but HPLC alone was not sufficient to differentiate between them. The HPLC eluent was directed to an ion trap mass spectrometer operating in negative-ion electrospray ionisation mode for MS/MS and MS/MS/MS experiments. This was essential to identify the various isomers having the same flavonoid core but different sugar chains.

The mass spectral fragmentation patterns characterised the linkages between the glycoside groups to allow their identification. In this way, isomeric kaempferol 3-O-neohesperidoside and 3-O-rutinoside were distinguished, as were several other isomeric pairs.

The research team declared that this is the first time that non-coloured flavonoids have been reported from this pollen and the value of HPLC for isomer separation and mass spectrometry for isomer identification has been illustrated.

The results expand the phytochemical knowledge of bee pollen from E. plantagineum. They will be useful for the quality control of commercial dietary supplements prepared from this bee pollen and for detecting their adulteration with other substances, which might be cheaper pollens from other sources or even non-pollen matter.

Related links:

* Rapid Communications in Mass Spectrometry 2010, 24, 801-806: "First report of non-coloured flavonoids in Echium plantagineum bee pollen: differentiation of isomers by liquid chromatography/ion trap mass spectrometry"

10 bulan....

Alhamdulillah Nor Hazman shafiq sudah berusia 10 bulan dan sudah mula berjalan beberapa langkah....seronok melayan kerenahnya.....he..he..moga anakanda menjadi anak yang soleh....InsyaAllah...

Pesta Sukan PASTI Serdang

Alhamdulillah anak sulungku berjaya menjadi johan dalam pertandingan bola sepak...moga anakanda berjaya dalam pelajaran juga...ayah akan senantisa mendoakan kamu...

Senarai Dosa2 Besar dari Kitab al-Kaba`ir

DOSA-DOSA BESAR


Al-Imam Azzahabiyy menyenaraikan dalam kitabnya "Al-Kabaair" jenis dosa-dosa besar melibatkan perkara-perkara seperti berikut:

01 - Belajar ilmu lalu tidak menerangkannya
02 -Persaksian palsu
03 - Berjudi
04 - Bersumpah palsu dan bohong
05 - Berbohong
06 - Tidak istinjak selepas kencing
07 - Perempuan pelacur
08 - Berbuat zalim terhadap yang lemah
09 - Berdebat dan memusuhi
10 - Bersifat dayus
11 - Bercakap kasar dengan orang tua
12 - Dusta nama Allah dan rasulnya
13 - Derhaka pada suami
14 - Derhaka pada hamba Allah
15 - Hakim yang zalim
16 - Homoseks
17 - Menipu dalam timbangan
18 -al-Abd al-Aabiq /iaituhamba yang lari dari tuannya
19 - Lelaki menyerupai wanita ( al-mutasyabbihin binnisak )
20 - Lari dari medan perang di jalan Allah
21 - Membunuh manusia
22 - Membunuh diri sendiri
23 - Mengamalkan sihir
24 - Meninggalkan sembahyang lima waktu
25 - Meninggalkan sembahyang jumaat
26 - Menderhaka ibu bapa
27 - Memutuskan hubungan silaturrahim
28 - Melakukan zina
29 - Makan harta anak yatim secara tidak betul
30 -Mengumpulkan kekayaan haram
31 - Memberi dan menerima rasuah
32 - Melabuhkan pakaian kerana berlagak sombong
33 -Berurusan dengan riba
34 - Minum arak
35 - Mencuri
36 - Merompak
37 - Melakukan kezaliman
38 - Melakukan pengkhianatan
39 - Mengungkit-ungkit pemberian
40 - Mengingkari janji
41 - Memfitnah
42 - Mengutuk orang islam
43 - Merasa aman dari kemurkaan Allah
44 - Menipu harta rampasan
45 - Melampaui batas
46 - Menuduh zina terhadap orang baik
47 - Memakai emas dan sutera (bagi lelaki)
48 - Mempercayai nujum dan sihir
49 - Wanita menyerupai lelaki ( al-Mutasyabbhihatu birrijal )
50 - Mencari-cari kesalahan orang lain
51 - Menganggu orang lain
52 - Menganggu tetangga
53 - Menyakiti dan memaki orang islam
54 - Mengintip dan membuka rahsia orang
55 - Mencaci sahabat Nabi
56 - Mengurangi wasiat
57 - Mengingkari takdir
58 - Putus asa dari rahmat Allah
59 - Penipuan dan kezaliman terhadap orang bawahan
60 - Riak dan menunjuk-nunjuki
61 - Syirikkan Allah dengan sesuatu yang lain
62 - Sombong serta angkuh
63 - Sembelih untuk selain Allah
64 - Tidak mengeluarkan zakat
65 - Tidak berpuasa di bulan ramadhan
66 - Tidak mengerjakan haji sedangkan bermampuan

thanks Ustaz Zahazan...

RENUNGAN : BILAKAH KAU AKAN BERTAUBAT

bahan ini adalah inspirasi daripada kitab Syarah al-Hikam Oleh guru kami Dr Zulkifli bin Muhammad al-Bakri dan sahabat kami Us Gunawan HafizahumalLah penulis kitab Masjid.Kedua-dua kitab ini diterbitkan oleh Telaga Biru sdn Bhd.


Maksudnya : Wahai orang-orang yang beriman! bertaubatlah kamu kepada Allah dengan " taubat Nasuha", Mudah-mudahan Tuhan kamu akan menghapuskan kesalahan-kesalahan kamu dan memasukkan kamu ke dalam syurga yang mengalir di bawahnya beberapa sungai, pada hari Allah tidak akan menghinakan Nabi dan orang-orang yang beriman bersama-sama dengannya; cahaya (iman dan amal soleh) mereka, bergerak cepat di hadapan mereka dan di sebelah kanan mereka (semasa mereka berjalan); mereka berkata (ketika orang-orang munafik meraba-raba dalam gelap-gelita): "Wahai Tuhan kami! sempurnakanlah bagi Kami cahaya kami, dan limpahkanlah keampunan kepada kami; Sesungguhnya Engkau Maha Kuasa atas tiap-tiap sesuatu". Surah at-Tahrim ayat 8.

Hayatilah ayat ini, ia adalah perintah daripada al-Haqq. Dia memerintahkan diri kita semua agar kembali kepadanya dengan meninggalkan segala kemaksiatan yang kecil mahupun yang besar. Secara hakikatnya ialah, seolah-olah Dia al-Haqq mengilhamkan dalam sanubari hatimu dengan berkata, “Wahai hambaku, tinggalkanlah pakaian burukmu itu (perbuatan dosa dan maksiat), dan kembalikah mengikat hubunganmu denganKu dengan melaksanakan ketaatan. Tinggalkanlah jalan yang jauh itu dan kemarilah dekat kepadaKu”.

Para ULAMA tazkiyyatunnufus telah menyatakan bahawa, taubat itu perlulah mestilah di dasari dengan ilmu pengetahuan dan keazaman serta usaha agar maksiat ditinggalkanSerta mestilah istiqamah untuk menuju kepada ketaatan melibatkan perilaku atau perbuatan.Perkara ini semuanya berkaitan dengan amalan ataupun routine hariannya. Amalan ini adalah menunjukkan kepada keimanan seseorang hamba.

Mengapakah taubat itu perlu di dasari kepada keimanan?. Ketahuilah bahawa ilmu pengetahuan merupakan dasar yang mengikat iman kepada Allah swt, sedangkan perilaku atau perbuatan merupakan sesuatu yang muncul daripada ilmu pengetahuan. Manakala amalan lahir daripada renungan, penghayatan dalam hati dan anggota badan serta kebiasaan. Oleh itu wahai para sahabat yang mencari jalan menuju kepadaNya, hendaklah dirimu mengenal ilmu pengetahuan tentang hal ini. Hendaklah dirimu mengatahui bahawa, perkara maksiat, derhaka dan lalai dalam laranganNya adalah punca terbesar wujudnya dosa-dosa. Dosa-dosa pula berkaitan dengan perbuatan-perbuatan jahat yang berasal dari pujuk rayu syaitan, dan hawa nafsu yg tidak ditarbiyyah.Yakinlah bahaw kita memiliki Allah yg bersifat dengan sifat alAfuww yang sentiasa memberi kemaafan terhadap hambaNya yang bertaubat kepadaNya. Ini juga disebutkan sebagai Rabbun Ghofurun...

dari Ustaz Zahazan...Thanks...

MENGAPA SAUDARA MERASA TIDAK CERIA ?

Dalam Ruangan Cerdik Baik oleh Dato Fazilah Kamsah

1. Tidak Berada Dalam HidayahNya.Hidayah bermaksud Petunjuk yg disertai dgn rahmatNya.Al-Ghazali berkata dlm Bidayatul Hidayah maksudnya : Hendaklah engkau tahu bahawa hidayah itu adalah buah drp ilmu yg dituntut dgn keikhlasan kdpNya.
2.Kejahilan.Kejahilan mengakibatkan kepayahan & penderitaan , contohnya orang2 yg tidak mahu belajar ilmu2 Islam hingga mngakibatkan kehidupannya penuh dgn pelbagai perkara yg diharamkan.Demikian pula sikap bodoh sombong dimana seseorg malu utk bertanya jalan2 keredhaan Allah dan pintu2 rezki yg sungguh banyak.Orang seperti ini akan terus berada dlm kesusahan krn kejahilan & kesombongannya itu.
3.Tidak mahu mengamalkan ilmunya.Orang seperti ini akan sentiasa berada dlm konflik kerana amalannya berlawanan dgn keyakinanannya,sebagai contoh para penerima rasuah,mereka tetap akan berkata dlm hati kecilnya bahwa ia adalah satu dosa.Tetapi krana desakan nafsu maka dia akan menurutinya.
4.Jauh daripada Allah swt.Ingat saudara,dalam hadis sahih, kumpulan kitab Ringkasan riyadus salihin Terbitan Telaga Biru,dlm bab Qiyamullail, apabila bangkit di awal pagi utk bertahajjud maka segenap ikatan iblis yg beratutan di badannya akan luput.Sebaliknya apabila dia terus tidur maka dia akan dikencing oleh syaitan pd telinganya, lalu bangkitlah dia kemudiannya dlm keadaan kaslan ( malas ) Khabitahannafs ( menderita ).Bagaimana tak menderita ????

Petikan daripada Majalah solusi, Isu Ke 19