Harmattan Dust Characteristics using Fourier Transform-Infrared and Gas Chromatography-Mass Spectrometry Method of Selected Sub-Saharan Region in African Stations

Polytechnic, Birnin Kebbi (12.4601°N, 4.4955°E), were the selected stations used in this study. The suspended Harmattan dust samples were obtained in glass petri plates using a direct deposition approach. Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatograph-Mass Spectrometry (GC-MS) were used to examine the samples collected. The results show that eleven functional groups were present in the samples, including =CH-H, - CH 3 , N-H, C=C, =C-H, C-H, O-H, C-N, C=O, C-O-C, and -CH 3 . According to GC-MS, the component (2-methoxy ethyl) had the greatest quality value (Q-Value) of 83, area percentage corresponding to time rating (RT) of 13.647, and CAS 018173-63-2 in the dust samples. It is therefore recommended that the Federal Republic of Nigeria's government increase funding for the research centers so that researchers can study all cities in the country and better observe the functional group metals present in the harmattan dust.


INTRODUCTION 1
The word Harmattan comes from Twi language, which means "Haramata", which is a banned term [1]. According to many scholars, harmattan originated in Sahara, the world's greatest dust plume [2]. Harmattan dust begins in November and lasts until roughly March of each year [1][2][3][4]. Harmattan season in northern Nigeria has been seen to blow from the Bodele depression, depositing samples into and throughout the region [5,6]. Annually, the harmattan dust phenomenon is recorded, and samples are transported across Nigeria by wind from the Sahara Desert to the Guinea Gulf [7][8][9]. According to literature *Corresponding Author Email: sholadavids1@gmail.com (A. Shola Rinde) [10,11], the harmattan takes an average of twenty-four hours to reach the Nigerian zone. According to literature [9,12,13], the chemical composition of harmattan dust has an impact on human health through various nasal disorders. However, according to literature [1,9,[14][15][16], harmattan dust can easily infiltrate the human respiratory system through the wind medium, allowing hazardous elements to enter the body. Uncertainly, the chemical makeup of harmattan dust has a deleterious impact on human health, according to literature [9,17,18]. According to Ezeh et al. [6,10,19,20] Adedokun [6,10,19,20], Adedokun et al. [19] and Adedayo [20], harmattan dust spells are usually accompanied by nighttime and morning drops, which affect the temperature. According to various studies, dust spells can last up to three to five days in the air before dissolving [1,10,19,[21][22][23]. As a result, the purpose of this study was to determine the functional groups present in harmattan dust using Fourier Transform Infrared (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS) equipment, as well as to investigate the level at which the groups are detected in the samples throughout the various stations.

MATERIAL AND METHODS
Suspended harmattan samples were obtained in four separate locations using 90 mm diameter cylindrical petri dishes with a height of 15.7 mm. Each of these glass petri dishes was kept safe from reptiles and external dust by being enclosed in a wire gauge (100x100x100) cm cage fixed to the tops of residential and some commercial buildings. The glass petri dish was chosen because of its heavy weight, which prevents it from being blown away by the wind and permits dust to accumulate in it when used in a direct open technique [1,3,24]. Several preventative precautions were implemented to prevent contamination by reptiles and roadway dust. The experimental setup for this investigation, on the other hand, is shown in Figure 1. Figure 2 depicts a map of the stations that were used. Table 1, on the other hand, illustrates the locations of the several sampling points at each station.

Sample preparation and characterization
The Agilent Technologies CARY 630FTIR Fourier Transform Infrared Machine was used to evaluate the samples collected at each location. The dry harmattan dust samples was digested before they could be examined using GC-MS. After that, the samples were run through FTIR and GC-MS equipment to determine their composition. Moreover, the quantitative and qualitative analyses of the sample were determined using this method.

RESULTS AND DISCUSSION
The functional groups detected in the samples collected at Waziri Umaru Federal Polytechnic, Birni Kebbi, are listed in Table 2. The FTIR spectrum of the collected sample is shown in Figure 3.  [25]. Observation from Table 4 shows the FTIR spectrum with the highest absorption peaks in     Table 5 shows the FTIR spectrum with the highest absorption peaks in the samples collected at USmanu Danfodio University, Sokoto. It shows the absorption regions of 3022.9 cm -1 , 2914.8 cm -1 , 2844.0 cm -1 , 1595.3 cm -1 , 1490.9 cm -1 , 1448.1 cm -1 , 1369.8 cm -1 , 1069.7 cm -1 , 1023.2 cm -1 , 903.9 cm -1 , 836.8 cm -1 , 743.6 cm -1 , 693.3 cm -1 . The absorption band at 3022.9 cm -1 corresponds to =C-H, the absorption band at 2914.8 cm -1 corresponds to -CH3, the absorption band at 2844.0 cm -1 corresponds to = -CH3, the absorption band at corresponds to -C-H, and the absorption band at 693.3 cm -1 corresponds to N-H, which is confirmed by [22,23,30]. The FTIR spectrum for Usmanu Danfodio University, Sokoto is shown in Figure 6.
FTIR spectra for the four locations compared with the FTIR Functional Group Chart Reference are listed in Table 6.
The GC-MS spectrum for Waziri Umaru Federal Polytechnic, Birni Kebbi and Kebbi State University of Science and Technology, Aliero are shown in Figure 7 and 8, respectively.          Table 9 shows that Benzene, 1,1'oxybis [3-phenoxy-is the compound with the highest Quality value of 83, area percent of 0.84, corresponding to the RT of 6.409, and CAS 000748-30-1 in dust samples obtained from Federal University of Agriculture, Zuru. Table 10 reveals that the top chemical in the dust samples obtained from Usmanu Danfodiyo University, Sokoto is Benzene, 1, 1'-oxybis [3-phenoxy-, with a Quality value of 83, an area of 6.409, a rating time of 0.84, and a CAS 000748-30-1. According to the findings, the elemental composition of the dust samples studied revealed that the percentage compositions of some elements are higher than the permissible WHO standard values, posing a health risk. As a result, it is suggested that suitable preventative measures and regulations be implemented to help minimize the effects of the observed elevated elements concentrations. Significant quantities of trace elements in the samples obtained throughout the four locations studied are thought to be harmful to human health. Inhalation is, of course, one of the principal causes of direct dust particle exposure in every section of the country.    Furthermore, the study discovered that the elemental composition of the dust samples studied has greater percentages than the WHO-recommended tolerable guideline levels for human health. As a result, it is suggested that suitable preventative measures and regulations be implemented to help minimize the effects of the observed elevated elements concentrations. For proper verification of Harmattan dust effect on human health, daily collection of the dust is recommended. In order to provide precautionary measures to every citizen of the nation, the researcher would like to inform the government of the federal agency in charge of monitoring the weather.